Resistance or tolerance: an examination of aphid (Sitobion yakini) phloem feeding on Betta and Betta-Dn wheat (Triticum aestivum)
- De Wet, L R, Botha, Christiaan E J
- Authors: De Wet, L R , Botha, Christiaan E J
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6517 , http://hdl.handle.net/10962/d1005945
- Description: Engineering pest resistance into crops is important. However, the mechanisms of resistance are not clearly understood. In this study, we examined the effects of aphid feeding on Russian wheat aphid-resistant and -susceptible cultivars of wheat (Triticum aestivum L.); Betta-Dn and Betta, respectively, by the grass aphid, Sitobion yakini (Eastop). These cultivars were grown with or without aphid colonies. In each case, we examined the plants specifically for the formation of wound callose associated with the phloem, using aniline blue and fluorescence microscopy. We observed that aphid feeding stimulated the formation of wound callose in the susceptible cultivar, but that callose was comparatively reduced in the resistant cultivar of wheat. In a separate series of experiments, the xenobiotic, 5, 6-carboxyfluorescein diacetate was applied to attached sink leaves, distal to feeding aphids. When leaf segments were examined four hours after application, little evidence of phloem transport of the fluorescent cleavage product, 5, 6-carboxyfluorescein (5, 6-CF), was evident below known aphid-probed sieve tubes. Low levels or absence of 5, 6-CF indicates that either the aphids have successfully redirected sap to themselves, or that the phloem is no longer functional. In contrast, 5, 6-CF transport was evident below sites of aphid probing in Betta-Dn, suggesting that the phloem was still capable of long-distance transport. In addition, callose deposition was reduced in Betta-Dn leaf phloem and it is surmised that transport was not as affected by aphid feeding in the resistant cultivar. This indicates that the ‘resistant’ wheat cultivar may in fact be tolerant to aphid feeding by successfully overcoming the nutrient drain that feeding aphids imposed on the phloem transport system.
- Full Text:
- Date Issued: 2007
- Authors: De Wet, L R , Botha, Christiaan E J
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6517 , http://hdl.handle.net/10962/d1005945
- Description: Engineering pest resistance into crops is important. However, the mechanisms of resistance are not clearly understood. In this study, we examined the effects of aphid feeding on Russian wheat aphid-resistant and -susceptible cultivars of wheat (Triticum aestivum L.); Betta-Dn and Betta, respectively, by the grass aphid, Sitobion yakini (Eastop). These cultivars were grown with or without aphid colonies. In each case, we examined the plants specifically for the formation of wound callose associated with the phloem, using aniline blue and fluorescence microscopy. We observed that aphid feeding stimulated the formation of wound callose in the susceptible cultivar, but that callose was comparatively reduced in the resistant cultivar of wheat. In a separate series of experiments, the xenobiotic, 5, 6-carboxyfluorescein diacetate was applied to attached sink leaves, distal to feeding aphids. When leaf segments were examined four hours after application, little evidence of phloem transport of the fluorescent cleavage product, 5, 6-carboxyfluorescein (5, 6-CF), was evident below known aphid-probed sieve tubes. Low levels or absence of 5, 6-CF indicates that either the aphids have successfully redirected sap to themselves, or that the phloem is no longer functional. In contrast, 5, 6-CF transport was evident below sites of aphid probing in Betta-Dn, suggesting that the phloem was still capable of long-distance transport. In addition, callose deposition was reduced in Betta-Dn leaf phloem and it is surmised that transport was not as affected by aphid feeding in the resistant cultivar. This indicates that the ‘resistant’ wheat cultivar may in fact be tolerant to aphid feeding by successfully overcoming the nutrient drain that feeding aphids imposed on the phloem transport system.
- Full Text:
- Date Issued: 2007
Restructuring implicational meaning through memory-based imagery: some historical notes
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6239 , http://hdl.handle.net/10962/d1007851
- Description: This paper provides a historical perspective on the recent increase in the clinical application of imagery techniques to restructure systems of implicational meaning that drive emotional distress or self-defeating behaviors. Janet's early application of such techniques was largely ignored except by a few hypnotherapists. Current applications in cognitive therapy were adapted and extended in the early 1980s from Perls’ Gestalt therapy methods. Some precursors to Perls are examined, as well as the work of some of those who developed and formulated the integration of his techniques into Beck's cognitive therapy. It is argued that this process amounted to a significant paradigm shift.
- Full Text:
- Date Issued: 2007
- Authors: Edwards, David J A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6239 , http://hdl.handle.net/10962/d1007851
- Description: This paper provides a historical perspective on the recent increase in the clinical application of imagery techniques to restructure systems of implicational meaning that drive emotional distress or self-defeating behaviors. Janet's early application of such techniques was largely ignored except by a few hypnotherapists. Current applications in cognitive therapy were adapted and extended in the early 1980s from Perls’ Gestalt therapy methods. Some precursors to Perls are examined, as well as the work of some of those who developed and formulated the integration of his techniques into Beck's cognitive therapy. It is argued that this process amounted to a significant paradigm shift.
- Full Text:
- Date Issued: 2007
Satisfied and dissatisfied South Africans: results from the General Household Survey in international comparison
- Authors: Moller, Valerie
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7112 , http://hdl.handle.net/10962/d1010744
- Description: Who are the satisfied South Africans 10 years into democracy? How do material factors contribute to their life satisfaction? These are the questions addressed in this paper. Earlier South African research has consistently found a close positive relationship between life satisfaction and material standards of living in the apartheid and post-apartheid era. Recently, a new source of information has become available to shed further light on the association between material and subjective well-being. In 2002, Statistics South Africa, the country’s official source of statistical information, agreed to ask South Africans participating in the General Household Survey whether they were satisfied or dissatisfied with life. The 2002 General Household Survey (n26’000) used a measure developed for the Euromodule that allows for international comparison. The wide-ranging information contained in South Africa’s official household survey offers a unique opportunity to explore what makes for satisfied and dissatisfied South Africans in relation to their material living standards. Results indicate that the improved living standards afforded to many black South Africans under democracy are associated with increases in life satisfaction. Furthermore, habituation does not appear to have diluted the positive relationship between living standards and well-being. However, political factors continue to play an important role in shaping subjective well-being. In conclusion, it is argued that material gains might also have restored the pride and dignity denied to black South Africans in the past.
- Full Text:
- Date Issued: 2007
- Authors: Moller, Valerie
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7112 , http://hdl.handle.net/10962/d1010744
- Description: Who are the satisfied South Africans 10 years into democracy? How do material factors contribute to their life satisfaction? These are the questions addressed in this paper. Earlier South African research has consistently found a close positive relationship between life satisfaction and material standards of living in the apartheid and post-apartheid era. Recently, a new source of information has become available to shed further light on the association between material and subjective well-being. In 2002, Statistics South Africa, the country’s official source of statistical information, agreed to ask South Africans participating in the General Household Survey whether they were satisfied or dissatisfied with life. The 2002 General Household Survey (n26’000) used a measure developed for the Euromodule that allows for international comparison. The wide-ranging information contained in South Africa’s official household survey offers a unique opportunity to explore what makes for satisfied and dissatisfied South Africans in relation to their material living standards. Results indicate that the improved living standards afforded to many black South Africans under democracy are associated with increases in life satisfaction. Furthermore, habituation does not appear to have diluted the positive relationship between living standards and well-being. However, political factors continue to play an important role in shaping subjective well-being. In conclusion, it is argued that material gains might also have restored the pride and dignity denied to black South Africans in the past.
- Full Text:
- Date Issued: 2007
Signatures of seaway closures and founder dispersal in the phylogeny of a circumglobally distributed seahorse lineage
- Teske, Peter R, Hamilton, Healy, Matthee, Conrad A, Barker, Nigel P
- Authors: Teske, Peter R , Hamilton, Healy , Matthee, Conrad A , Barker, Nigel P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6549 , http://hdl.handle.net/10962/d1006005
- Description: The importance of vicariance events on the establishment of phylogeographic patterns in the marine environment is well documented, and generally accepted as an important cause of cladogenesis. Founder dispersal (i.e. long-distance dispersal followed by founder effect speciation) is also frequently invoked as a cause of genetic divergence among lineages, but its role has long been challenged by vicariance biogeographers. Founder dispersal is likely to be common in species that colonize remote habitats by means of rafting (e.g. seahorses), as long-distance dispersal events are likely to be rare and subsequent additional recruitment from the source habitat is unlikely. In the present study, the relative importance of vicariance and founder dispersal as causes of cladogenesis in a circumglobally distributed seahorse lineage was investigated using molecular dating. A phylogeny was reconstructed using sequence data from mitochondrial and nuclear markers, and the well-documented closure of the Central American seaway was used as a primary calibration point to test whether other bifurcations in the phylogeny could also have been the result of vicariance events. The feasibility of three other vicariance events was explored: a) the closure of the Indonesian Seaway, resulting in sister lineages associated with the Indian Ocean and West Pacific, respectively; b) the closure of the Tethyan Seaway, resulting in sister lineages associated with the Indo-Pacific and Atlantic Ocean, respectively, and c) continental break-up during the Mesozoic followed by spreading of the Atlantic Ocean, resulting in pairs of lineages with amphi-Atlantic distribution patterns.
- Full Text:
- Date Issued: 2007
- Authors: Teske, Peter R , Hamilton, Healy , Matthee, Conrad A , Barker, Nigel P
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6549 , http://hdl.handle.net/10962/d1006005
- Description: The importance of vicariance events on the establishment of phylogeographic patterns in the marine environment is well documented, and generally accepted as an important cause of cladogenesis. Founder dispersal (i.e. long-distance dispersal followed by founder effect speciation) is also frequently invoked as a cause of genetic divergence among lineages, but its role has long been challenged by vicariance biogeographers. Founder dispersal is likely to be common in species that colonize remote habitats by means of rafting (e.g. seahorses), as long-distance dispersal events are likely to be rare and subsequent additional recruitment from the source habitat is unlikely. In the present study, the relative importance of vicariance and founder dispersal as causes of cladogenesis in a circumglobally distributed seahorse lineage was investigated using molecular dating. A phylogeny was reconstructed using sequence data from mitochondrial and nuclear markers, and the well-documented closure of the Central American seaway was used as a primary calibration point to test whether other bifurcations in the phylogeny could also have been the result of vicariance events. The feasibility of three other vicariance events was explored: a) the closure of the Indonesian Seaway, resulting in sister lineages associated with the Indian Ocean and West Pacific, respectively; b) the closure of the Tethyan Seaway, resulting in sister lineages associated with the Indo-Pacific and Atlantic Ocean, respectively, and c) continental break-up during the Mesozoic followed by spreading of the Atlantic Ocean, resulting in pairs of lineages with amphi-Atlantic distribution patterns.
- Full Text:
- Date Issued: 2007
South African research in the hydrological sciences : 2003 -2006 : IUGG report
- Authors: Hughes, Denis A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:7087 , http://hdl.handle.net/10962/d1012415
- Description: The principal activities of South African researchers in hydrology and water resources during the reporting period have been concerned with ground- and surface-water interactions, rainfall-runoff modelling, the establishment of improved regional water resource databases, the ecological Reserve, and investigating the likely consequences of climate change. Most of these studies have a strong emphasis on supporting the provisions of the National Water Act of 1998. Research programmes are benefiting from international and regional cooperation. In contrast, the lack of young scientists entering the field poses the greatest threat to hydrological research in South Africa.
- Full Text:
- Date Issued: 2007
- Authors: Hughes, Denis A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:7087 , http://hdl.handle.net/10962/d1012415
- Description: The principal activities of South African researchers in hydrology and water resources during the reporting period have been concerned with ground- and surface-water interactions, rainfall-runoff modelling, the establishment of improved regional water resource databases, the ecological Reserve, and investigating the likely consequences of climate change. Most of these studies have a strong emphasis on supporting the provisions of the National Water Act of 1998. Research programmes are benefiting from international and regional cooperation. In contrast, the lack of young scientists entering the field poses the greatest threat to hydrological research in South Africa.
- Full Text:
- Date Issued: 2007
South Asian diasporic women's short fiction: the South African contribution
- Authors: Naidu, Samantha
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: vital:26376 , http://hdl.handle.net/10962/54037 , https://orcid.org/0000-0001-9456-8657
- Description: Although Indian Women S Short Fiction Has Always Enjoyed Equal Importance And Popularity As Their Novels, Very Little Critical Attention Has Been Paid To It So Far. Indian Women S Short Fiction Seeks To Fulfil This Long Felt Need. It Puts Together Fifteen Perceptive And Analytical Articles By Scholars Across The World. The Articles, Which Are Focussed On Native Indian Writing As Well As Diasporic Short Fiction, Deal With Such Interesting Literary Issues As Construction Of Femininity, Disablement And Enablement, Bengali Heritage, Hybrid Identities, Nostalgia, Representation Of The Partition Violence, Tradition And Modernity, And Cultural Perspectivism.
- Full Text: false
- Date Issued: 2007
- Authors: Naidu, Samantha
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: vital:26376 , http://hdl.handle.net/10962/54037 , https://orcid.org/0000-0001-9456-8657
- Description: Although Indian Women S Short Fiction Has Always Enjoyed Equal Importance And Popularity As Their Novels, Very Little Critical Attention Has Been Paid To It So Far. Indian Women S Short Fiction Seeks To Fulfil This Long Felt Need. It Puts Together Fifteen Perceptive And Analytical Articles By Scholars Across The World. The Articles, Which Are Focussed On Native Indian Writing As Well As Diasporic Short Fiction, Deal With Such Interesting Literary Issues As Construction Of Femininity, Disablement And Enablement, Bengali Heritage, Hybrid Identities, Nostalgia, Representation Of The Partition Violence, Tradition And Modernity, And Cultural Perspectivism.
- Full Text: false
- Date Issued: 2007
Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H, Sanborn, Allen F, Phillips, Polly K F
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, Polly K F
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
- Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
- Full Text:
- Date Issued: 2007
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, Polly K F
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
- Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
- Full Text:
- Date Issued: 2007
Stratigraphic correlation of the Awahab and Tafelberg Formations, Etendeka Group, Namibia, and location of an eruptive site for flood basalt volcanism
- Marsh, Julian S, Milner, Simon C
- Authors: Marsh, Julian S , Milner, Simon C
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6738 , http://hdl.handle.net/10962/d1007552 , http://dx.doi.org/10.1016/j.jafrearsci.2007.04.004
- Description: Detailed field and geochemical investigations in the vicinity of the type section of the Tafelberg Formation of the early Cretaceous Etendeka Group, NW Namibia, have revealed the existence of a large eruptive vent in the lower part of the regional volcanic sequence produced by Strombolian and Vulcanian eruptions. The vent is filled with the thick, differentiated, ponded Kudu-Run olivine-rich basaltic flow, which has a distinctive low Zr/Y geochemical signature as well as a Tafelberg-type tabular basalt and the Nil Desperandum latite. Field evidence indicates that the Kudu-Run basalt and the latite were erupted from fissures located within the vent. Associated with the vent is an extensive pyroclastic apron extending from the vent edge and which is interbedded with the regional stratigraphy. Blocks of Precambrain basement lithologies occur within this deposit and indicate that the vent was excavated to a depth of at least 350 m below the palaeosurface at that time. The original Tafelberg Formation type section described by Erlank et al. [Erlank, A.J., Marsh, J.S., Duncan, A.R., Miller, R.McG., Hawkesworth, C.H., Betton, P.J., Rex, D.C. 1984. Geochemistry and petrogenesis of the Etendeka volcanic rocks from SWA/Namibia, 195–247. In: Erlank, A.J. (Ed.), Petrogenesis of Volcanic Rocks of the Karoo province. Special Publication of the Geological Society of South Africa, vol. 13, 395 p.] the Tafelberg Gully section, crosses from the lower part of the regional sequence into the intra-vent sequence and returns to the regional sequence higher up. In doing so it includes some of the localized intra-vent flows and excludes a number of flows which are part of the regional sequence in its lower part, thus rendering it inappropriate as a type section. A revised type section for the Tafelberg Formation is described by combining the upper part of the Tafelberg Gully section with a new section of 14 flows at the base of the regional sequence in the Tafelberg North (TBN) section some 2 km N of the Tafeleberg Gully. Distinctive flows in the TBN section can be mapped southwards where their precise stratigraphic relationship to the northward-thinning Springbok and Goboboseb Quarts Latite members of the Awahab Formation can be demonstrated. These stratigraphic relationships are entirely consistent with palaeomagnetic reversal stratigraphy and demonstrate that the same N–R–N polarity sequence occurs in the type sections of the Awahab and Tafelberg formations. Thus, the Awahab and Tafelberg magma systems were contemporaneous but the Tafelberg system outlived that of the Awahab. The Awahab system was built from eruptive centres located S of the Huab River whereas the Tafelberg vents were located further north. , Full text article access in Journal of African Earth Sciences, 48 (5). pp. 329-340. Available: http://dx.doi.org/10.1016/j.jafrearsci.2007.04.004
- Full Text: false
- Date Issued: 2007
- Authors: Marsh, Julian S , Milner, Simon C
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6738 , http://hdl.handle.net/10962/d1007552 , http://dx.doi.org/10.1016/j.jafrearsci.2007.04.004
- Description: Detailed field and geochemical investigations in the vicinity of the type section of the Tafelberg Formation of the early Cretaceous Etendeka Group, NW Namibia, have revealed the existence of a large eruptive vent in the lower part of the regional volcanic sequence produced by Strombolian and Vulcanian eruptions. The vent is filled with the thick, differentiated, ponded Kudu-Run olivine-rich basaltic flow, which has a distinctive low Zr/Y geochemical signature as well as a Tafelberg-type tabular basalt and the Nil Desperandum latite. Field evidence indicates that the Kudu-Run basalt and the latite were erupted from fissures located within the vent. Associated with the vent is an extensive pyroclastic apron extending from the vent edge and which is interbedded with the regional stratigraphy. Blocks of Precambrain basement lithologies occur within this deposit and indicate that the vent was excavated to a depth of at least 350 m below the palaeosurface at that time. The original Tafelberg Formation type section described by Erlank et al. [Erlank, A.J., Marsh, J.S., Duncan, A.R., Miller, R.McG., Hawkesworth, C.H., Betton, P.J., Rex, D.C. 1984. Geochemistry and petrogenesis of the Etendeka volcanic rocks from SWA/Namibia, 195–247. In: Erlank, A.J. (Ed.), Petrogenesis of Volcanic Rocks of the Karoo province. Special Publication of the Geological Society of South Africa, vol. 13, 395 p.] the Tafelberg Gully section, crosses from the lower part of the regional sequence into the intra-vent sequence and returns to the regional sequence higher up. In doing so it includes some of the localized intra-vent flows and excludes a number of flows which are part of the regional sequence in its lower part, thus rendering it inappropriate as a type section. A revised type section for the Tafelberg Formation is described by combining the upper part of the Tafelberg Gully section with a new section of 14 flows at the base of the regional sequence in the Tafelberg North (TBN) section some 2 km N of the Tafeleberg Gully. Distinctive flows in the TBN section can be mapped southwards where their precise stratigraphic relationship to the northward-thinning Springbok and Goboboseb Quarts Latite members of the Awahab Formation can be demonstrated. These stratigraphic relationships are entirely consistent with palaeomagnetic reversal stratigraphy and demonstrate that the same N–R–N polarity sequence occurs in the type sections of the Awahab and Tafelberg formations. Thus, the Awahab and Tafelberg magma systems were contemporaneous but the Tafelberg system outlived that of the Awahab. The Awahab system was built from eruptive centres located S of the Huab River whereas the Tafelberg vents were located further north. , Full text article access in Journal of African Earth Sciences, 48 (5). pp. 329-340. Available: http://dx.doi.org/10.1016/j.jafrearsci.2007.04.004
- Full Text: false
- Date Issued: 2007
The comparison of in vitro release methods for the evaluation of oxytocin release from Pluronic® F127 parenteral formulations
- Chaibva, Faith A, Walker, Roderick B
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6351 , http://hdl.handle.net/10962/d1006033
- Description: The objective of these studies was to develop a discriminatory in vitro release test for assessing formulation factors that may affect oxytocin (OT) release during formulation development studies of a Pluronic® F127 OT in situ gel-forming parenteral dosage form. An appropriate release assessment method should be able to discriminate between the performance of different formulation compositions (1, 2), and this was the primary criterion used for selection of an appropriate test procedure during the test method development process. ANOVA and the difference (f1) and similarity (f2)factors were used to evaluate the discriminatory behavior of different test methods that were investigated in these studies. The in vitro release tests that were investigated included the use of USP Apparatus 1, 2, and 3; a dialysis bag in USP Apparatus 2; and a membrane-less diffusion method. It was concluded that the use of USP Apparatus 3 was best able to discriminate between OT release for the different formulations tested. USP Apparatus 3 was thus considered the most suitable in vitro release test apparatus for studying formulation factors affecting OT release during the development of a parenteral dosage form prepared using Pluronic® F127.
- Full Text:
- Date Issued: 2007
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6351 , http://hdl.handle.net/10962/d1006033
- Description: The objective of these studies was to develop a discriminatory in vitro release test for assessing formulation factors that may affect oxytocin (OT) release during formulation development studies of a Pluronic® F127 OT in situ gel-forming parenteral dosage form. An appropriate release assessment method should be able to discriminate between the performance of different formulation compositions (1, 2), and this was the primary criterion used for selection of an appropriate test procedure during the test method development process. ANOVA and the difference (f1) and similarity (f2)factors were used to evaluate the discriminatory behavior of different test methods that were investigated in these studies. The in vitro release tests that were investigated included the use of USP Apparatus 1, 2, and 3; a dialysis bag in USP Apparatus 2; and a membrane-less diffusion method. It was concluded that the use of USP Apparatus 3 was best able to discriminate between OT release for the different formulations tested. USP Apparatus 3 was thus considered the most suitable in vitro release test apparatus for studying formulation factors affecting OT release during the development of a parenteral dosage form prepared using Pluronic® F127.
- Full Text:
- Date Issued: 2007
The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp
- Wilson, J R U, Ajuonub, O, Center, R D, Hill, Martin P, Julien, M H, Katagira, F F, Neuenschwander, P, Njoka, S W, Ogwang, J, Reeder, R H, Van, T
- Authors: Wilson, J R U , Ajuonub, O , Center, R D , Hill, Martin P , Julien, M H , Katagira, F F , Neuenschwander, P , Njoka, S W , Ogwang, J , Reeder, R H , Van, T
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6927 , http://hdl.handle.net/10962/d1011918 , https://orcid.org/0000-0003-0579-5298
- Description: There has been some debate recently about the cause of the decline of water hyacinth on Lake Victoria. While much of this evidence points to classical biological control as the major factor, the El Niño associated weather pattern of the last quarter of 1997 and the first half of 1998 has confused the issue. We argue first that the reductions in water hyacinth on Lake Victoria were ultimately caused by the widespread and significant damage to plants by Neochetina spp., although this process was increased by the stormy weather associated with the El Niño event; second that increased waves and current on Lake Victoria caused by El Niño redistributed water hyacinth plants around the lake; and third that a major lake-wide resurgence of water hyacinth plants on Lake Victoria has not occurred and will not occur unless the weevil populations are disrupted. We conclude that the population crash of water hyacinth on Lake Victoria would not have occurred in the absence of the weevils, but that it may have been hastened by stormy weather associated with the El Niño event.
- Full Text:
- Date Issued: 2007
- Authors: Wilson, J R U , Ajuonub, O , Center, R D , Hill, Martin P , Julien, M H , Katagira, F F , Neuenschwander, P , Njoka, S W , Ogwang, J , Reeder, R H , Van, T
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6927 , http://hdl.handle.net/10962/d1011918 , https://orcid.org/0000-0003-0579-5298
- Description: There has been some debate recently about the cause of the decline of water hyacinth on Lake Victoria. While much of this evidence points to classical biological control as the major factor, the El Niño associated weather pattern of the last quarter of 1997 and the first half of 1998 has confused the issue. We argue first that the reductions in water hyacinth on Lake Victoria were ultimately caused by the widespread and significant damage to plants by Neochetina spp., although this process was increased by the stormy weather associated with the El Niño event; second that increased waves and current on Lake Victoria caused by El Niño redistributed water hyacinth plants around the lake; and third that a major lake-wide resurgence of water hyacinth plants on Lake Victoria has not occurred and will not occur unless the weevil populations are disrupted. We conclude that the population crash of water hyacinth on Lake Victoria would not have occurred in the absence of the weevils, but that it may have been hastened by stormy weather associated with the El Niño event.
- Full Text:
- Date Issued: 2007
The effect of physico-chemical parameters and chemical compounds on the activity of β-d-galactosidase (B-GAL), a marker enzyme for indicator microorganisms in water
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6470 , http://hdl.handle.net/10962/d1005800 , https://doi.org/10.1016/j.chemosphere.2007.02.050
- Description: The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
- Full Text:
- Date Issued: 2007
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6470 , http://hdl.handle.net/10962/d1005800 , https://doi.org/10.1016/j.chemosphere.2007.02.050
- Description: The presence of coliforms in polluted water was determined enzymatically (in situ) by directly monitoring the activity of beta-d-galactosidase (B-GAL) through the hydrolysis of the yellow chromogenic subtrate, chlorophenol red beta-d-galactopyranoside (CPRG), which produced a red chlorophenol red (CPR) product. The objectives of this study were to monitor the effect of compounds commonly found in the environment and used in water treatment on a B-GAL CPRG assay and to investigate the differences between the environmental B-GAL enzyme and the pure commercial enzyme. Environmental B-GAL was optimally active at pH 7.8. Two temperature optima were observed at 35 and 55 degrees C, respectively. B-GAL activity was strongly inhibited by silver and copper ions. While calcium and ferrous ions at lower concentrations (50-100mgl(-1)) increased the enzyme activity, a reduction was observed at higher concentrations (200mgl(-1)). Sodium hypochlorite, normally used in rural areas to disinfect water gradually decreased B-GAL activity at concentrations between 0 and 5600ppm for both the commercial and environmental enzymes. B-GAL from the environment behaved differently from its commercially available counterpart.
- Full Text:
- Date Issued: 2007
The effect of sulfide on -glucosidases: implications for starch degradation in anaerobic bioreactors
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6463 , http://hdl.handle.net/10962/d1005792 , dx.doi.org/10.1016/j.chemosphere.2006.03.011
- Description: Membrane associated α-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 °C and pH optima of 8.0 for the α-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l[superscript (−1)]) resulted in the complete loss of all α-glucosidase activity in both the MR and SR. β-Glucosidase activities in our bioreactors were previously shown to be stimulated in the presence of sulfide. α-Glucosidases, in contrast, are inhibited by sulfide. This differential effect of sulfide on α-glucosidase and β-glucosidase activities is highlighted and is of crucial consequence to the respective degradation and utilization of starch and cellulose substrates in natural anaerobic environments and anaerobic bioreactors specifically designed for the accelerated digestion of wastewater sludge under biosulfidogenic conditions.
- Full Text:
- Date Issued: 2007
The effect of sulfide on -glucosidases: implications for starch degradation in anaerobic bioreactors
- Authors: Wutor, V C , Togo, C A
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6463 , http://hdl.handle.net/10962/d1005792 , dx.doi.org/10.1016/j.chemosphere.2006.03.011
- Description: Membrane associated α-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 °C and pH optima of 8.0 for the α-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l[superscript (−1)]) resulted in the complete loss of all α-glucosidase activity in both the MR and SR. β-Glucosidase activities in our bioreactors were previously shown to be stimulated in the presence of sulfide. α-Glucosidases, in contrast, are inhibited by sulfide. This differential effect of sulfide on α-glucosidase and β-glucosidase activities is highlighted and is of crucial consequence to the respective degradation and utilization of starch and cellulose substrates in natural anaerobic environments and anaerobic bioreactors specifically designed for the accelerated digestion of wastewater sludge under biosulfidogenic conditions.
- Full Text:
- Date Issued: 2007
The effects of buffer molarity, agitation rate and mesh size on verapamil release from modified release mini-tablets using USP Apparatus 3
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6386 , http://hdl.handle.net/10962/d1006307
- Description: The effects of agitation rate, buffer molarity,and mesh size on the dissolution rate of verapamil hydrochloride from sustained release matrix tablets were studied using USP Apparatus 3. Eudragit® and Carbopol® were used as rate-retarding polymers in tablets prepared by wet granulation.The study was conducted to determine whether the drugs exhibit similar release characteristics when tested under the same dissolution conditions. It was found that the dissolution rate of verapamil hydrochloride was affected by the variables assessed in these studies.
- Full Text:
- Date Issued: 2007
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2007
- Language: English
- Type: text , Article
- Identifier: vital:6386 , http://hdl.handle.net/10962/d1006307
- Description: The effects of agitation rate, buffer molarity,and mesh size on the dissolution rate of verapamil hydrochloride from sustained release matrix tablets were studied using USP Apparatus 3. Eudragit® and Carbopol® were used as rate-retarding polymers in tablets prepared by wet granulation.The study was conducted to determine whether the drugs exhibit similar release characteristics when tested under the same dissolution conditions. It was found that the dissolution rate of verapamil hydrochloride was affected by the variables assessed in these studies.
- Full Text:
- Date Issued: 2007
The Emerging Role of ubuntu-botho in Developing a Consensual South African Legal Culture
- Authors: Kruuse, Helen , Midgley, Rob
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54224 , vital:26413 , https://dspace.library.uu.nl/handle/1874/27652
- Description: Legal culture in apartheid South Africa has variously been described as conservative and positivist, with judicial deference to the executive and to parliamentary sovereignty; formalistic, technical and authoritarian; and ‘of reasoned argument’ and justification. Until 1994, law drew its legitimacy from the very fact that it was state sanctioned, and the material context or the social aftermath of the application of a rule was in many instances deemed irrelevant. However, the adoption, first, of the interim Constitution, and later the final Constitution, saw a desire to transform this legal culture. The Constitution is now more than a formal document regulating public power: it also embodies a normative value system in terms of which judges are called upon to interpret laws and their application.
- Full Text:
- Date Issued: 2007
- Authors: Kruuse, Helen , Midgley, Rob
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54224 , vital:26413 , https://dspace.library.uu.nl/handle/1874/27652
- Description: Legal culture in apartheid South Africa has variously been described as conservative and positivist, with judicial deference to the executive and to parliamentary sovereignty; formalistic, technical and authoritarian; and ‘of reasoned argument’ and justification. Until 1994, law drew its legitimacy from the very fact that it was state sanctioned, and the material context or the social aftermath of the application of a rule was in many instances deemed irrelevant. However, the adoption, first, of the interim Constitution, and later the final Constitution, saw a desire to transform this legal culture. The Constitution is now more than a formal document regulating public power: it also embodies a normative value system in terms of which judges are called upon to interpret laws and their application.
- Full Text:
- Date Issued: 2007
The importance of dry woodlands and forests in rural livelihoods and poverty alleviation in South Africa
- Shackleton, Charlie M, Shackleton, Sheona E, Buiten, Erik, Bird, Neil
- Authors: Shackleton, Charlie M , Shackleton, Sheona E , Buiten, Erik , Bird, Neil
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6653 , http://hdl.handle.net/10962/d1007066
- Description: Indigenous forests and savannas, along with plantation forests, offer numerous benefits to rural communities and society at large. Yet, the role of forests and forestry in contributing to sustainable livelihoods and poverty alleviation are widely debated. However, much of the debate pertains to lessons from the humid tropics, with little consideration of the widespread dry forests and savannas. This paper considers the role of dry forest types, including savannas, using South Africa as a case example. It concludes that a large proportion of the population makes use of forests and the resources from them. These are vital components of local livelihoods, which probably prevent people from slipping into deeper poverty. Moreover, for a measurable proportion, engagement in informal forest activities, as well as the formal forestry sector, has resulted in them being able to move out of poverty. Additionally, the generally dry nature of forests in South Africa, coupled with the high unemployment rate, limit the extent of alternative locally based livelihood options, thereby magnifying the contributions from forests and forest products. The depressing effects of widespread HIV/AIDS on labour availability, economic activities and livelihoods has exacerbated peoples' dependence on forest products.
- Full Text:
- Date Issued: 2007
- Authors: Shackleton, Charlie M , Shackleton, Sheona E , Buiten, Erik , Bird, Neil
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6653 , http://hdl.handle.net/10962/d1007066
- Description: Indigenous forests and savannas, along with plantation forests, offer numerous benefits to rural communities and society at large. Yet, the role of forests and forestry in contributing to sustainable livelihoods and poverty alleviation are widely debated. However, much of the debate pertains to lessons from the humid tropics, with little consideration of the widespread dry forests and savannas. This paper considers the role of dry forest types, including savannas, using South Africa as a case example. It concludes that a large proportion of the population makes use of forests and the resources from them. These are vital components of local livelihoods, which probably prevent people from slipping into deeper poverty. Moreover, for a measurable proportion, engagement in informal forest activities, as well as the formal forestry sector, has resulted in them being able to move out of poverty. Additionally, the generally dry nature of forests in South Africa, coupled with the high unemployment rate, limit the extent of alternative locally based livelihood options, thereby magnifying the contributions from forests and forest products. The depressing effects of widespread HIV/AIDS on labour availability, economic activities and livelihoods has exacerbated peoples' dependence on forest products.
- Full Text:
- Date Issued: 2007
The law of carriage
- Authors: Keep, Helen
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54235 , vital:26415 , https://dspace.library.uu.nl/handle/1874/27652
- Description: Commercial Law.
- Full Text: false
- Date Issued: 2007
- Authors: Keep, Helen
- Date: 2007
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54235 , vital:26415 , https://dspace.library.uu.nl/handle/1874/27652
- Description: Commercial Law.
- Full Text: false
- Date Issued: 2007
The need for an inland fisheries policy in South Africa : a case study of the North West Province
- Weyl, Olaf L F, Potts, Warren M, Rouhani, Q
- Authors: Weyl, Olaf L F , Potts, Warren M , Rouhani, Q
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6769 , http://hdl.handle.net/10962/d1008056
- Description: In contrast to many other African countries, inland fisheries in South Africa are poorly developed and the fish populations in many of the country’s 3 000 major dams are under-utilised. While the primary purpose South Africa’s dams is to supply water for domestic and agricultural use, there has been an increasing realisation that their fish populations could make a contribution to food security through the establishment of capture fisheries. Historically, the fish in most South African dams have primarily been utilised for recreational fishing purposes, as subsistence use was criminalised by the apartheid regime in all waters except in the former homeland areas. This legacy persists as many of South Africa’s rural communities do not have a fishing tradition and there is a lack of an institutional framework to facilitate managed and sustainable access to the fish resource in inland waters. Current utilisation of many inland dams is often complicated by the existence of multiple authorities and interest groups, often with competing agendas. As a result, the economic potential of these water bodies is unknown and often grossly underutilised. Our study outlines a case study of fisheries resources in the North West Province of South Africa that could be used for the creation of income and food security for local communities through the development of subsistence, commercial, and recreational fisheries. The study identifies the lack of guidelines for the development of inland fisheries and the lack of an inland fisheries policy, both at the provincial and national level, as major bottlenecks for the sustainable development of these resources and outlines possible focal areas for intervention.
- Full Text:
- Date Issued: 2007
- Authors: Weyl, Olaf L F , Potts, Warren M , Rouhani, Q
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6769 , http://hdl.handle.net/10962/d1008056
- Description: In contrast to many other African countries, inland fisheries in South Africa are poorly developed and the fish populations in many of the country’s 3 000 major dams are under-utilised. While the primary purpose South Africa’s dams is to supply water for domestic and agricultural use, there has been an increasing realisation that their fish populations could make a contribution to food security through the establishment of capture fisheries. Historically, the fish in most South African dams have primarily been utilised for recreational fishing purposes, as subsistence use was criminalised by the apartheid regime in all waters except in the former homeland areas. This legacy persists as many of South Africa’s rural communities do not have a fishing tradition and there is a lack of an institutional framework to facilitate managed and sustainable access to the fish resource in inland waters. Current utilisation of many inland dams is often complicated by the existence of multiple authorities and interest groups, often with competing agendas. As a result, the economic potential of these water bodies is unknown and often grossly underutilised. Our study outlines a case study of fisheries resources in the North West Province of South Africa that could be used for the creation of income and food security for local communities through the development of subsistence, commercial, and recreational fisheries. The study identifies the lack of guidelines for the development of inland fisheries and the lack of an inland fisheries policy, both at the provincial and national level, as major bottlenecks for the sustainable development of these resources and outlines possible focal areas for intervention.
- Full Text:
- Date Issued: 2007
The reintroduction of large carnivores to the Eastern Cape, South Africa: an assessment
- Hayward, M W, Kerley, Graham I H, Adendorff, John, Moolman, Lucius C, O'Brien, John, Sholto-Douglas, Angus, Bissett, Charlene, Bean, Peter, Fogarty, Alan, Howarth, Dale, Slater, Richard
- Authors: Hayward, M W , Kerley, Graham I H , Adendorff, John , Moolman, Lucius C , O'Brien, John , Sholto-Douglas, Angus , Bissett, Charlene , Bean, Peter , Fogarty, Alan , Howarth, Dale , Slater, Richard
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6900 , http://hdl.handle.net/10962/d1011662 , http://dx.doi.org/10.1017/S0030605307001767
- Description: Recently, conservation estate in South Africa's Eastern Cape Province has increased 10-fold resulting in large predators being increasingly reintroduced to restore ecological integrity and maximize tourism. We describe the reintroductions of large carnivores (>10 kg) that have occurred in the Eastern Cape and use various criteria to assess their success. Lion Panthera leo reintroduction has been highly successful with a population of 56 currently extant in the region and problems of overpopulation arising. The African wild dog Lycaon pictus population has increased to 24 from a founder population of 11. Preliminary results for spotted hyaenas Crocuta crocuta also indicate success. Wild populations of leopards Panthera pardus exist on several reserves and have been supplemented by translocated individuals, although deaths of known individuals have occurred and no estimate of reproduction is available. Cheetah Acinonyx jubatus reintroduction has also been less successful with 36 individuals reintroduced and 23 cubs being born but only 41 individuals surviving in 2005. Criteria for assessing the success of reintroductions of species that naturally occur in low densities, such as top predators, generally have limited value. Carrying capacity for large predators is unknown and continued monitoring and intensive management will be necessary in enclosed, and possibly all, conservation areas in the Eastern Cape to ensure conservation success.
- Full Text:
- Date Issued: 2007
- Authors: Hayward, M W , Kerley, Graham I H , Adendorff, John , Moolman, Lucius C , O'Brien, John , Sholto-Douglas, Angus , Bissett, Charlene , Bean, Peter , Fogarty, Alan , Howarth, Dale , Slater, Richard
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6900 , http://hdl.handle.net/10962/d1011662 , http://dx.doi.org/10.1017/S0030605307001767
- Description: Recently, conservation estate in South Africa's Eastern Cape Province has increased 10-fold resulting in large predators being increasingly reintroduced to restore ecological integrity and maximize tourism. We describe the reintroductions of large carnivores (>10 kg) that have occurred in the Eastern Cape and use various criteria to assess their success. Lion Panthera leo reintroduction has been highly successful with a population of 56 currently extant in the region and problems of overpopulation arising. The African wild dog Lycaon pictus population has increased to 24 from a founder population of 11. Preliminary results for spotted hyaenas Crocuta crocuta also indicate success. Wild populations of leopards Panthera pardus exist on several reserves and have been supplemented by translocated individuals, although deaths of known individuals have occurred and no estimate of reproduction is available. Cheetah Acinonyx jubatus reintroduction has also been less successful with 36 individuals reintroduced and 23 cubs being born but only 41 individuals surviving in 2005. Criteria for assessing the success of reintroductions of species that naturally occur in low densities, such as top predators, generally have limited value. Carrying capacity for large predators is unknown and continued monitoring and intensive management will be necessary in enclosed, and possibly all, conservation areas in the Eastern Cape to ensure conservation success.
- Full Text:
- Date Issued: 2007
The risk of phallocentrism in masculinities studies: how a revision of the concept of patriarchy might help
- Authors: Macleod, Catriona I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6216 , http://hdl.handle.net/10962/d1006268
- Description: In this article I critique South African work on masculinities through a fine grained reading of Morrell’s introductions to three texts. While this work appears, on first reading, to contribute to pro-feminist theorising, I argue that it inadvertently falls into a phallocentric trap. This is achieved in three ways: firstly, and most crudely, through conflating women and men into a singular, universal model that is in reality the masculine appearing as the universal; secondly, and more subtly, through concentrating almost exclusively on men and masculinities, thereby marginalising women (again); and thirdly, through constructing multiplicities of masculinities – this allows men to resist hegemonic masculinity, but never undo masculinity itself. In this way, the possibility of deconstructing the feminine/masculine binary recedes and the concept of patriarchy gets sidelined. I argue for a reinsertion of the notion of patriarchy into our study of gender, but also that the very notion of patriarchy needs revision in order to accommodate the multiple fissures that occur between men.
- Full Text:
- Date Issued: 2007
- Authors: Macleod, Catriona I
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6216 , http://hdl.handle.net/10962/d1006268
- Description: In this article I critique South African work on masculinities through a fine grained reading of Morrell’s introductions to three texts. While this work appears, on first reading, to contribute to pro-feminist theorising, I argue that it inadvertently falls into a phallocentric trap. This is achieved in three ways: firstly, and most crudely, through conflating women and men into a singular, universal model that is in reality the masculine appearing as the universal; secondly, and more subtly, through concentrating almost exclusively on men and masculinities, thereby marginalising women (again); and thirdly, through constructing multiplicities of masculinities – this allows men to resist hegemonic masculinity, but never undo masculinity itself. In this way, the possibility of deconstructing the feminine/masculine binary recedes and the concept of patriarchy gets sidelined. I argue for a reinsertion of the notion of patriarchy into our study of gender, but also that the very notion of patriarchy needs revision in order to accommodate the multiple fissures that occur between men.
- Full Text:
- Date Issued: 2007
The structural and functional diversity of Hsp70 proteins from Plasmodium falciparum
- Shonhai, Addmore, Boshoff, Aileen, Blatch, Gregory L
- Authors: Shonhai, Addmore , Boshoff, Aileen , Blatch, Gregory L
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6486 , http://hdl.handle.net/10962/d1006269 , http://dx.doi.org/10.1110/ps.072918107
- Description: It is becoming increasingly apparent that heat shock proteins play an important role in the survival of Plasmodium falciparum against temperature changes associated with its passage from the cold-blooded mosquito vector to the warm-blooded human host. Interest in understanding the possible role of P. falciparum Hsp70s in the life cycle of the parasite has led to the identification of six HSP70 genes. Although most research attention has focused primarily on one of the cytosolic Hsp70s (PfHsp70-1) and its endoplasmic reticulum homolog (PfHsp70-2), further functional insights could be inferred from the structural motifs exhibited by the rest of the Hsp70 family members of P. falciparum. There is increasing evidence that suggests that PfHsp70-1 could play an important role in the life cycle of P. falciparum both as a chaperone and immunogen. In addition, P. falciparum Hsp70s and Hsp40 partners are implicated in the intracellular and extracellular trafficking of proteins. This review summarizes data emerging from studies on the chaperone role of P. falciparum Hsp70s, taking advantage of inferences gleaned from their structures and information on their cellular localization. The possible associations between P. falciparum Hsp70s with their cochaperone partners as well as other chaperones and proteins are discussed.
- Full Text:
- Date Issued: 2007
- Authors: Shonhai, Addmore , Boshoff, Aileen , Blatch, Gregory L
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6486 , http://hdl.handle.net/10962/d1006269 , http://dx.doi.org/10.1110/ps.072918107
- Description: It is becoming increasingly apparent that heat shock proteins play an important role in the survival of Plasmodium falciparum against temperature changes associated with its passage from the cold-blooded mosquito vector to the warm-blooded human host. Interest in understanding the possible role of P. falciparum Hsp70s in the life cycle of the parasite has led to the identification of six HSP70 genes. Although most research attention has focused primarily on one of the cytosolic Hsp70s (PfHsp70-1) and its endoplasmic reticulum homolog (PfHsp70-2), further functional insights could be inferred from the structural motifs exhibited by the rest of the Hsp70 family members of P. falciparum. There is increasing evidence that suggests that PfHsp70-1 could play an important role in the life cycle of P. falciparum both as a chaperone and immunogen. In addition, P. falciparum Hsp70s and Hsp40 partners are implicated in the intracellular and extracellular trafficking of proteins. This review summarizes data emerging from studies on the chaperone role of P. falciparum Hsp70s, taking advantage of inferences gleaned from their structures and information on their cellular localization. The possible associations between P. falciparum Hsp70s with their cochaperone partners as well as other chaperones and proteins are discussed.
- Full Text:
- Date Issued: 2007