Iris colour in passerine birds: why be bright-eyed?
- Craig, Adrian J F K, Hulley, Patrick E
- Authors: Craig, Adrian J F K , Hulley, Patrick E
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6902 , http://hdl.handle.net/10962/d1011756
- Description: An initial survey of iris coloration in passerine birds (Aves: Passeriformes) showed that a brightly pigmented iris is much more common in southern African and Australian birds than in those from Europe, temperate North America, and Venezuela. However, the only statistical correlation reflected the distribution of particular bird families in these regions. Ten family-level groups considered to represent monophyletic taxa were then selected for a more detailed analysis, comparing iris coloration with distribution, status, taxonomy, plumage patterns, and some biological and behavioural characters for 1143 species. No pattern associating iris colour with particular traits was common to all families, but within families there were statistically significant associations with both plumage and biology. Our expectation that social behaviour would be an important predictor of iris colour was not supported, but critical information is still lacking for many species. Future studies of avian behavioural ecology should examine critically the role of iris coloration in individual species. , Rhodes Centenary issue
- Full Text:
- Date Issued: 2004
- Authors: Craig, Adrian J F K , Hulley, Patrick E
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6902 , http://hdl.handle.net/10962/d1011756
- Description: An initial survey of iris coloration in passerine birds (Aves: Passeriformes) showed that a brightly pigmented iris is much more common in southern African and Australian birds than in those from Europe, temperate North America, and Venezuela. However, the only statistical correlation reflected the distribution of particular bird families in these regions. Ten family-level groups considered to represent monophyletic taxa were then selected for a more detailed analysis, comparing iris coloration with distribution, status, taxonomy, plumage patterns, and some biological and behavioural characters for 1143 species. No pattern associating iris colour with particular traits was common to all families, but within families there were statistically significant associations with both plumage and biology. Our expectation that social behaviour would be an important predictor of iris colour was not supported, but critical information is still lacking for many species. Future studies of avian behavioural ecology should examine critically the role of iris coloration in individual species. , Rhodes Centenary issue
- Full Text:
- Date Issued: 2004
Molecular chaperones in biology, medicine and protein biotechnology
- Boshoff, Aileen, Nicoll, William S, Hennessy, Fritha, Ludewig, M H, Daniel, Sheril, Modisakeng, Keoagile W, Shonhai, Addmore, McNamara, Caryn, Bradley, Graeme, Blatch, Gregory L
- Authors: Boshoff, Aileen , Nicoll, William S , Hennessy, Fritha , Ludewig, M H , Daniel, Sheril , Modisakeng, Keoagile W , Shonhai, Addmore , McNamara, Caryn , Bradley, Graeme , Blatch, Gregory L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6457 , http://hdl.handle.net/10962/d1004479
- Description: Molecular chaperones consist of several highly conserved families of proteins, many of which consist of heat shock proteins. The primary function of molecular chaperones is to facilitate the folding or refolding of proteins, and therefore they play an important role in diverse cellular processes including protein synthesis, protein translocation, and the refolding or degradation of proteins after cell stress. Cells are often exposed to different stressors, resulting in protein misfolding and aggregation. It is now well established that the levels of certain molecular chaperones are elevated during stress to provide protection to the cell. The focus of this review is on the impact of molecular chaperones in biology, medicine and protein biotechnology, and thus covers both fundamental and applied aspects of chaperone biology. Attention is paid to the functions and applications of molecular chaperones from bacterial and eukaryotic cells, focusing on the heat shock proteins 90 (Hsp90), 70 (Hsp70) and 40 (Hsp40) classes of chaperones, respectively. The role of these classes of chaperones in human diseases is discussed, as well as the parts played by chaperones produced by the causative agents of malaria and trypanosomiasis. Recent advances have seen the application of chaperones in improving the yields of a particular target protein in recombinant protein production. The prospects for the targeted use of molecular chaperones for the over-production of recombinant proteins is critically reviewed, and current research on these chaperones at Rhodes University is also discussed.
- Full Text:
- Date Issued: 2004
- Authors: Boshoff, Aileen , Nicoll, William S , Hennessy, Fritha , Ludewig, M H , Daniel, Sheril , Modisakeng, Keoagile W , Shonhai, Addmore , McNamara, Caryn , Bradley, Graeme , Blatch, Gregory L
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6457 , http://hdl.handle.net/10962/d1004479
- Description: Molecular chaperones consist of several highly conserved families of proteins, many of which consist of heat shock proteins. The primary function of molecular chaperones is to facilitate the folding or refolding of proteins, and therefore they play an important role in diverse cellular processes including protein synthesis, protein translocation, and the refolding or degradation of proteins after cell stress. Cells are often exposed to different stressors, resulting in protein misfolding and aggregation. It is now well established that the levels of certain molecular chaperones are elevated during stress to provide protection to the cell. The focus of this review is on the impact of molecular chaperones in biology, medicine and protein biotechnology, and thus covers both fundamental and applied aspects of chaperone biology. Attention is paid to the functions and applications of molecular chaperones from bacterial and eukaryotic cells, focusing on the heat shock proteins 90 (Hsp90), 70 (Hsp70) and 40 (Hsp40) classes of chaperones, respectively. The role of these classes of chaperones in human diseases is discussed, as well as the parts played by chaperones produced by the causative agents of malaria and trypanosomiasis. Recent advances have seen the application of chaperones in improving the yields of a particular target protein in recombinant protein production. The prospects for the targeted use of molecular chaperones for the over-production of recombinant proteins is critically reviewed, and current research on these chaperones at Rhodes University is also discussed.
- Full Text:
- Date Issued: 2004
Reduction in transport in wheat (Triticum aestivum) is caused by sustained phloem feeding by the Russian wheat aphid (Diuraphis noxia)
- Botha, Christiaan E J, Matsiliza, Babalwa
- Authors: Botha, Christiaan E J , Matsiliza, Babalwa
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6498 , http://hdl.handle.net/10962/d1004498
- Description: The Russian wheat aphid (Diuraphis noxia) feeds preferentially from the phloem of longitudinal veins of nonresistant wheat leaves. The xenobiotic, 5,6-CFDA was applied to exposed leaf blade mesophyll cells in control and aphid-infested plants. In control plants, the fluorophore moved approximately 5–6cm from the point of application of 5,6-CFDA within 3h of application. The fluorochrome was transported in the sieve tube companion cell complex, including those in the numerous interconnecting transverse veins. Leaf blades on which the Russian wheat aphid had been feeding demonstrated a marked decrease in 5,6-CF transport. Aphids feeding on the leaves formed local sinks and redirected the fluorophore (and presumably associated assimilate) to the aphids’ gut, with little longitudinal translocation of 5,6-CF below inserted stylets or aphid feeding areas. Aniline blue staining revealed massive deposits of wound and reaction callose caused by the aphids, with callose associated with the sieve plates, pore-plasmodesma between the companion cells and their associated sieve tubes, as well as with plasmodesmal aggregates in parenchymatous elements within the vascular bundles. Leaves that had been colonised by aphids but from which the aphids were removed, showed extensive wound callose deposits, which persisted for up to 48h after removal of aphid colonies, suggesting that the damage caused by aphid feeding is a long-term, non-transient event in non-resistant plants.
- Full Text:
- Date Issued: 2004
- Authors: Botha, Christiaan E J , Matsiliza, Babalwa
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6498 , http://hdl.handle.net/10962/d1004498
- Description: The Russian wheat aphid (Diuraphis noxia) feeds preferentially from the phloem of longitudinal veins of nonresistant wheat leaves. The xenobiotic, 5,6-CFDA was applied to exposed leaf blade mesophyll cells in control and aphid-infested plants. In control plants, the fluorophore moved approximately 5–6cm from the point of application of 5,6-CFDA within 3h of application. The fluorochrome was transported in the sieve tube companion cell complex, including those in the numerous interconnecting transverse veins. Leaf blades on which the Russian wheat aphid had been feeding demonstrated a marked decrease in 5,6-CF transport. Aphids feeding on the leaves formed local sinks and redirected the fluorophore (and presumably associated assimilate) to the aphids’ gut, with little longitudinal translocation of 5,6-CF below inserted stylets or aphid feeding areas. Aniline blue staining revealed massive deposits of wound and reaction callose caused by the aphids, with callose associated with the sieve plates, pore-plasmodesma between the companion cells and their associated sieve tubes, as well as with plasmodesmal aggregates in parenchymatous elements within the vascular bundles. Leaves that had been colonised by aphids but from which the aphids were removed, showed extensive wound callose deposits, which persisted for up to 48h after removal of aphid colonies, suggesting that the damage caused by aphid feeding is a long-term, non-transient event in non-resistant plants.
- Full Text:
- Date Issued: 2004
The general election in Lesotho, May 2002: adapting to MMP
- Fox, Roddy C, Southall, Roger J
- Authors: Fox, Roddy C , Southall, Roger J
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6680 , http://hdl.handle.net/10962/d1006673
- Description: Voters in the small southern African kingdom of Lesotho went to the polls on 25 May 2002, in the third general election since the country returned to democracy following a long period of civilian dictatorship (1970–1986) and military rule (1986–1993). Voting in all Lesotho’s general elections has usually gone smoothly, yet in every case prior to 2002 the results have been challenged, with varying severity, by the losing parties (Weisfelder, 1999). This occurred most notably in 1970, when the ruling Basotho National Party (BNP) lost the election but overrode the result, and subsequently in 1998, when the BNP—then in opposition—was at the core of an alliance of electoral losers; in the months that followed, and with the quiet support of the security forces, the capital was so paralysed that the government called for external assistance to restore order. The result was military intervention by South Africa and Botswana (who acted on behalf of the Southern African Development Community, SADC), the restoration of power to the Lesotho Congress for Democracy (LCD), and an extended period when, backed by South African muscle, long overdue reforms of the military and police were implemented. These reforms were matched by negotiations between the parties about adopting a new electoral system. The outcome moved Lesotho away from the first-past-the-post system inherited from Britain at independence (which in 1993 and 1998 had resulted in highly imbalanced results favouring the winning party) towards a Mixed Member Proportional (MMP) system. Lesotho became the first country in Africa to adopt MMP at a time when discussion of electoral system change was becoming widespread throughout the continent. The issue in Lesotho in 2002 was not merely whether MMP would provide greater electoral legitimacy and political stability; subsequent events have provided a resounding ‘Yes’ (Elklit, 2002 and Southall, 2003). But there were questions about the practicality of the new system and whether voters would understand it. Was it possible to explain a new voting system to an electorate in one of Africa’s poorest countries? The main focus of this Note is to demonstrate that voters can adapt to electoral system change. Thus, it throws doubt on arguments that electoral reforms in Africa should be avoided due to a lack of sophistication among poor and largely uneducated voters. Electors in Lesotho appeared to have no great difficulty in understanding the broad principles of the new electoral system, even if the detailed mechanics of ‘mixed’ voting systems may have been beyond them.
- Full Text:
- Date Issued: 2004
- Authors: Fox, Roddy C , Southall, Roger J
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6680 , http://hdl.handle.net/10962/d1006673
- Description: Voters in the small southern African kingdom of Lesotho went to the polls on 25 May 2002, in the third general election since the country returned to democracy following a long period of civilian dictatorship (1970–1986) and military rule (1986–1993). Voting in all Lesotho’s general elections has usually gone smoothly, yet in every case prior to 2002 the results have been challenged, with varying severity, by the losing parties (Weisfelder, 1999). This occurred most notably in 1970, when the ruling Basotho National Party (BNP) lost the election but overrode the result, and subsequently in 1998, when the BNP—then in opposition—was at the core of an alliance of electoral losers; in the months that followed, and with the quiet support of the security forces, the capital was so paralysed that the government called for external assistance to restore order. The result was military intervention by South Africa and Botswana (who acted on behalf of the Southern African Development Community, SADC), the restoration of power to the Lesotho Congress for Democracy (LCD), and an extended period when, backed by South African muscle, long overdue reforms of the military and police were implemented. These reforms were matched by negotiations between the parties about adopting a new electoral system. The outcome moved Lesotho away from the first-past-the-post system inherited from Britain at independence (which in 1993 and 1998 had resulted in highly imbalanced results favouring the winning party) towards a Mixed Member Proportional (MMP) system. Lesotho became the first country in Africa to adopt MMP at a time when discussion of electoral system change was becoming widespread throughout the continent. The issue in Lesotho in 2002 was not merely whether MMP would provide greater electoral legitimacy and political stability; subsequent events have provided a resounding ‘Yes’ (Elklit, 2002 and Southall, 2003). But there were questions about the practicality of the new system and whether voters would understand it. Was it possible to explain a new voting system to an electorate in one of Africa’s poorest countries? The main focus of this Note is to demonstrate that voters can adapt to electoral system change. Thus, it throws doubt on arguments that electoral reforms in Africa should be avoided due to a lack of sophistication among poor and largely uneducated voters. Electors in Lesotho appeared to have no great difficulty in understanding the broad principles of the new electoral system, even if the detailed mechanics of ‘mixed’ voting systems may have been beyond them.
- Full Text:
- Date Issued: 2004
The Southern Ocean Group at Rhodes University: seventeen years of biological oceanography in the Southern Ocean reviewed
- McQuaid, Christopher D, Froneman, P William
- Authors: McQuaid, Christopher D , Froneman, P William
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6834 , http://hdl.handle.net/10962/d1010423
- Description: This paper reviews the main findings of the Southern Ocean Group at Rhodes University over the last 17 years. A primary contribution has been the development of conceptual models of the physical-biological driving mechanisms that support enormous seasonal populations of land-based top predators at the Prince Edward Islands. Collectively, these models are referred to as the life-support system of the islands. Near-shore subcomponents of the ecosystem, including inshore feeding predators, are largely supported by autochthonous primary production of kelps and localized diatom blooms. These energy sources feed indirectly into top predator populations via the benthic communities. A crucial link is formed by the bottom-dwelling shrimp, Nauticaris marionis, which feeds largely on benthic species and detritus and is eaten by a number of diving seabirds. The frontal systems that lie north and south of the islands are important feeding grounds for offshore feeding birds. A decadal-scale southward shift in the position of the Sub-antarctic Front towards the islands is reflected in increases in populations of these species. , Rhodes Centenary issue
- Full Text:
- Date Issued: 2004
- Authors: McQuaid, Christopher D , Froneman, P William
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6834 , http://hdl.handle.net/10962/d1010423
- Description: This paper reviews the main findings of the Southern Ocean Group at Rhodes University over the last 17 years. A primary contribution has been the development of conceptual models of the physical-biological driving mechanisms that support enormous seasonal populations of land-based top predators at the Prince Edward Islands. Collectively, these models are referred to as the life-support system of the islands. Near-shore subcomponents of the ecosystem, including inshore feeding predators, are largely supported by autochthonous primary production of kelps and localized diatom blooms. These energy sources feed indirectly into top predator populations via the benthic communities. A crucial link is formed by the bottom-dwelling shrimp, Nauticaris marionis, which feeds largely on benthic species and detritus and is eaten by a number of diving seabirds. The frontal systems that lie north and south of the islands are important feeding grounds for offshore feeding birds. A decadal-scale southward shift in the position of the Sub-antarctic Front towards the islands is reflected in increases in populations of these species. , Rhodes Centenary issue
- Full Text:
- Date Issued: 2004
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