Phylogenetic congruence of mealybugs and their primary endosymbionts
- Authors: Downie, D A , Gullan, P J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6905 , http://hdl.handle.net/10962/d1011858 , http://dx.doi.org/10.1111/j.1420-9101.2004.00834.x
- Description: Tight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
- Full Text:
- Date Issued: 2005
- Authors: Downie, D A , Gullan, P J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6905 , http://hdl.handle.net/10962/d1011858 , http://dx.doi.org/10.1111/j.1420-9101.2004.00834.x
- Description: Tight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
- Full Text:
- Date Issued: 2005
Post-traumatic stress disorder as a public health concern in South Africa
- Authors: Edwards, D J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6229 , http://hdl.handle.net/10962/d1007779
- Description: This article briefly surveys the extent to which traumatic events are a feature of life all over Africa and provides a comprehensive review of research that documents the pervasiveness of traumatic events in South Africa and the prevalence of PTSD symptoms. The material reviewed includes statistics on crime, violence and accidents, research from clinical settings, and surveys. Several provide evidence for the causal link between traumatic events and the development of PTSD. These studies show that PTSD has been and continues to be a significant problem for public health in South Africa, affecting individuals in all sectors of society and as much a concern with respect to children as to adults.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, D J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6229 , http://hdl.handle.net/10962/d1007779
- Description: This article briefly surveys the extent to which traumatic events are a feature of life all over Africa and provides a comprehensive review of research that documents the pervasiveness of traumatic events in South Africa and the prevalence of PTSD symptoms. The material reviewed includes statistics on crime, violence and accidents, research from clinical settings, and surveys. Several provide evidence for the causal link between traumatic events and the development of PTSD. These studies show that PTSD has been and continues to be a significant problem for public health in South Africa, affecting individuals in all sectors of society and as much a concern with respect to children as to adults.
- Full Text:
- Date Issued: 2005
A successful cognitive-behavioural intervention that failed : a case study of adolescent conduct disorder at a school for the disadvantaged
- Mashalaba, Eugenia D, Edwards, David J A
- Authors: Mashalaba, Eugenia D , Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6273 , http://hdl.handle.net/10962/d1008273
- Description: Conduct Disorder (CD) is a widespread problem in southern Africa. The aim of the study was to design, implement and evaluate a multi-modal cognitive-behavioural intervention based on treatments developed overseas, in order to investigate whether this approach can be transported to a South African school for deprived children. The target adolescent had a history of severely disruptive behaviour and was facing expulsion from a shelter for homeless children and his school. A thorough assessment served as the basis for a case formulation and treatment plan. Intervention included 23 individual sessions focussing on bereavement and the learning of self-control skills and prosocial behaviours, as well as contingency management training for school and shelter staff. Progress was tracked with a behaviour checklist completed daily by the teacher and regular interviews with school and shelter staff. After four months, the disruptive behaviour was eliminated. However, he was involved in stealing with some other learners and expelled anyway. Nevertheless the case study provides evidence for the transportability of the cognitive-behavioural approach to this kind of setting and documents the way in which a comprehensive intervention can be tailored to the needs of a child with a severely deprived background and little social support.
- Full Text:
- Date Issued: 2005
- Authors: Mashalaba, Eugenia D , Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6273 , http://hdl.handle.net/10962/d1008273
- Description: Conduct Disorder (CD) is a widespread problem in southern Africa. The aim of the study was to design, implement and evaluate a multi-modal cognitive-behavioural intervention based on treatments developed overseas, in order to investigate whether this approach can be transported to a South African school for deprived children. The target adolescent had a history of severely disruptive behaviour and was facing expulsion from a shelter for homeless children and his school. A thorough assessment served as the basis for a case formulation and treatment plan. Intervention included 23 individual sessions focussing on bereavement and the learning of self-control skills and prosocial behaviours, as well as contingency management training for school and shelter staff. Progress was tracked with a behaviour checklist completed daily by the teacher and regular interviews with school and shelter staff. After four months, the disruptive behaviour was eliminated. However, he was involved in stealing with some other learners and expelled anyway. Nevertheless the case study provides evidence for the transportability of the cognitive-behavioural approach to this kind of setting and documents the way in which a comprehensive intervention can be tailored to the needs of a child with a severely deprived background and little social support.
- Full Text:
- Date Issued: 2005
An LC-MS-MS method for the determination of cyclizine in human serum
- Mohammadi, Ali, Kanfer, Isadore, Sewram, V, Walker, Roderick B
- Authors: Mohammadi, Ali , Kanfer, Isadore , Sewram, V , Walker, Roderick B
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6408 , http://hdl.handle.net/10962/d1006481
- Description: Cyclizine is a piperazine derivative with anti-emetic activity that is useful in the prevention and treatment of nausea and vomiting associated with motion sickness. A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is presented for the quantitation of cyclizine in serum. Sample pretreatment involved liquid-liquid extraction of 200 μl of serum with dichloromethane after the addition of 100 μl each of ammonium hydroxide and internal standard solutions. The extracts were analyzed by HPLC on a Luna ® C18 reversed-phase column and an ion-trap mass spectrometer with an electrospray interface. A limit of detection of 1 ng/ml was determined which allowed for the reliable measurement of cyclizine in the serum of human subjects. The method was found to be linear over the calibration range of 2.5-100 ng/ml. The applicability of this method was demonstrated by the analysis of serum obtained from a human volunteer following administration of a single 50 mg cyclizine hydrochloride tablet. The reported method was observed to have the necessary sensitivity, selectivity, precision and accuracy for monitoring cyclizine concentrations in human subjects following oral administration.
- Full Text:
- Date Issued: 2005
- Authors: Mohammadi, Ali , Kanfer, Isadore , Sewram, V , Walker, Roderick B
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6408 , http://hdl.handle.net/10962/d1006481
- Description: Cyclizine is a piperazine derivative with anti-emetic activity that is useful in the prevention and treatment of nausea and vomiting associated with motion sickness. A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is presented for the quantitation of cyclizine in serum. Sample pretreatment involved liquid-liquid extraction of 200 μl of serum with dichloromethane after the addition of 100 μl each of ammonium hydroxide and internal standard solutions. The extracts were analyzed by HPLC on a Luna ® C18 reversed-phase column and an ion-trap mass spectrometer with an electrospray interface. A limit of detection of 1 ng/ml was determined which allowed for the reliable measurement of cyclizine in the serum of human subjects. The method was found to be linear over the calibration range of 2.5-100 ng/ml. The applicability of this method was demonstrated by the analysis of serum obtained from a human volunteer following administration of a single 50 mg cyclizine hydrochloride tablet. The reported method was observed to have the necessary sensitivity, selectivity, precision and accuracy for monitoring cyclizine concentrations in human subjects following oral administration.
- Full Text:
- Date Issued: 2005
The experiences and needs of HIV/AIDS counsellors at a South African hospital
- Authors: Nulty, M , Edwards, D J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6269 , http://hdl.handle.net/10962/d1008268
- Description: To increase the availability of HIV/AIDS counselling in South Africa, nurses have been trained to serve as counsellors within hospital services. The aim of the study was to document the experiences and needs of nurse HIV/AIDS counsellors at a small South African hospital (with 279 beds and 10 medical doctors on the staff). The design was a qualitative, multiple-case study. The sample consisted of four nurse counsellors and the co-ordinator of HIV/AIDS services at the hospital. Three semi-structured interviews with the counsellors were used as the basis for case narratives of their experiences. These narratives were in turn subjected to content analysis to determine the range and nature of the concerns identified by the counsellors. The counsellors found their HIV/AIDS counselling work to be emotionally demanding and identified several significant problems. These were related to confidentiality, stigmatisation, motional responses to informing clients of their HIV-positive status, cultural and contextual factors and situational stressors related to the organisation of the work environment. They did not feel sufficiently supported by their work infrastructure. It is recommended that in setting up counselling services of this sort, managers need to be aware of the need for ongoing support in the form of facilitated groups, professional supervision, managerial attention to problems in the working environment, and regular in-service training.
- Full Text:
- Date Issued: 2005
- Authors: Nulty, M , Edwards, D J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6269 , http://hdl.handle.net/10962/d1008268
- Description: To increase the availability of HIV/AIDS counselling in South Africa, nurses have been trained to serve as counsellors within hospital services. The aim of the study was to document the experiences and needs of nurse HIV/AIDS counsellors at a small South African hospital (with 279 beds and 10 medical doctors on the staff). The design was a qualitative, multiple-case study. The sample consisted of four nurse counsellors and the co-ordinator of HIV/AIDS services at the hospital. Three semi-structured interviews with the counsellors were used as the basis for case narratives of their experiences. These narratives were in turn subjected to content analysis to determine the range and nature of the concerns identified by the counsellors. The counsellors found their HIV/AIDS counselling work to be emotionally demanding and identified several significant problems. These were related to confidentiality, stigmatisation, motional responses to informing clients of their HIV-positive status, cultural and contextual factors and situational stressors related to the organisation of the work environment. They did not feel sufficiently supported by their work infrastructure. It is recommended that in setting up counselling services of this sort, managers need to be aware of the need for ongoing support in the form of facilitated groups, professional supervision, managerial attention to problems in the working environment, and regular in-service training.
- Full Text:
- Date Issued: 2005
Reproductive biology of a riverine cyprinid, Labeo umbratus (Teleostei: Cyprinidae), in small South African reservoirs
- Potts, Warren M, Booth, Anthony J, Hecht, Thomas, Andrew, Timothy G
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
Derivation of quantitative management objectives for annual instream water temperatures in the Sabie River using a biological index
- Rivers-Moore, N A, Jewitt, G P W, Weeks, D C
- Authors: Rivers-Moore, N A , Jewitt, G P W , Weeks, D C
- Date: 2005
- Language: English
- Type: text , Article
- Identifier: vital:7093 , http://hdl.handle.net/10962/d1012426
- Description: Adaptive management of river systems assumes uncertainty and makes provision for system variability. Inherent within this management approach is that perceived limits of 'acceptable' system variability are regarded not only as testable hypotheses, but also as playing a central role in maintaining biodiversity. While the Kruger National Park currently functions as a flagship conservation area in South Africa, projected increases in air temperatures as a consequence of global climate change present challenges in conserving this biodiversity inside the established land boundaries. Within the rivers of the Kruger National Park, a management goal of maintaining biodiversity requires a clearer understanding of system variability. One component of this is water temperature, an important water quality parameter defining the distribution patterns of aquatic organisms. In this study, Chiloglanis anoterus Crass (1960) (Pisces: Mochokidae) was selected as a biological indicator of changes in annual water temperatures within the Sabie River in the southern Kruger National Park. Relative abundances of C. anoterus were determined using standard electro-fishing surveys. The presence or absence of C. anoterus was linked to cumulative annual heat units using a logistic regression model, and a critical annual cumulative water temperature threshold estimated. A correlative relationship between this temperature threshold and a biological index using a C. anoterus condition factor provides river ecologists with a tool to assess ecologically significant warming trends in Sabie River water temperatures. A similar approach could be applied with relative ease to other Southern African river systems. Further testing of this hypothesis is suggested, as part of the adaptive management cycle.
- Full Text:
- Date Issued: 2005
- Authors: Rivers-Moore, N A , Jewitt, G P W , Weeks, D C
- Date: 2005
- Language: English
- Type: text , Article
- Identifier: vital:7093 , http://hdl.handle.net/10962/d1012426
- Description: Adaptive management of river systems assumes uncertainty and makes provision for system variability. Inherent within this management approach is that perceived limits of 'acceptable' system variability are regarded not only as testable hypotheses, but also as playing a central role in maintaining biodiversity. While the Kruger National Park currently functions as a flagship conservation area in South Africa, projected increases in air temperatures as a consequence of global climate change present challenges in conserving this biodiversity inside the established land boundaries. Within the rivers of the Kruger National Park, a management goal of maintaining biodiversity requires a clearer understanding of system variability. One component of this is water temperature, an important water quality parameter defining the distribution patterns of aquatic organisms. In this study, Chiloglanis anoterus Crass (1960) (Pisces: Mochokidae) was selected as a biological indicator of changes in annual water temperatures within the Sabie River in the southern Kruger National Park. Relative abundances of C. anoterus were determined using standard electro-fishing surveys. The presence or absence of C. anoterus was linked to cumulative annual heat units using a logistic regression model, and a critical annual cumulative water temperature threshold estimated. A correlative relationship between this temperature threshold and a biological index using a C. anoterus condition factor provides river ecologists with a tool to assess ecologically significant warming trends in Sabie River water temperatures. A similar approach could be applied with relative ease to other Southern African river systems. Further testing of this hypothesis is suggested, as part of the adaptive management cycle.
- Full Text:
- Date Issued: 2005
Reproductive biology of ningu, Labeo victorianus (pisces: cyprinidae), in the kagera and Sio rivers, Uganda
- Rutaisire, Justus, Booth, Anthony J
- Authors: Rutaisire, Justus , Booth, Anthony J
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125864 , vital:35827 , https://doi.10.1007/s10641-004-5564-8
- Description: We investigated aspects of the reproductive biology of the cyprinid fish, Labeo victorianus, locally known as ningu, in the Kagera and Sio Rivers, Uganda. These rivers represent the last remaining refuges for this species within Uganda. L. victorianus is a highly fecund, potamodrometic fish that migrates upstream to spawn. Spawning is generally synchronised with the bimodal water level maxima observed within the rivers. There were, however, some deviations from this pattern. We caught sexually mature fish throughout the year in the Sio River, and noticed that spawing started before the second rainfall peak. Fish from the Kagera matured at significantly larger sizes than fish from the Sio River. Male and female fish, from both rivers, fed intensively during the non-breeding months accumulating significant fat reserves; a probable energy storage mechanism prior to their spawning migrations. The differences between the populations is probably a phenotypic response to differing abiotic factors such as river size, flow velocity and food availability.
- Full Text:
- Date Issued: 2005
- Authors: Rutaisire, Justus , Booth, Anthony J
- Date: 2005
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125864 , vital:35827 , https://doi.10.1007/s10641-004-5564-8
- Description: We investigated aspects of the reproductive biology of the cyprinid fish, Labeo victorianus, locally known as ningu, in the Kagera and Sio Rivers, Uganda. These rivers represent the last remaining refuges for this species within Uganda. L. victorianus is a highly fecund, potamodrometic fish that migrates upstream to spawn. Spawning is generally synchronised with the bimodal water level maxima observed within the rivers. There were, however, some deviations from this pattern. We caught sexually mature fish throughout the year in the Sio River, and noticed that spawing started before the second rainfall peak. Fish from the Kagera matured at significantly larger sizes than fish from the Sio River. Male and female fish, from both rivers, fed intensively during the non-breeding months accumulating significant fat reserves; a probable energy storage mechanism prior to their spawning migrations. The differences between the populations is probably a phenotypic response to differing abiotic factors such as river size, flow velocity and food availability.
- Full Text:
- Date Issued: 2005
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