1,721,203 research outputs found
Differential Growth-Related Gene Expression in Abalone (Haliotis midae)
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Genome size estimation and karyotype composition of the South African abalone Haliotis midae
No full textKaryotype and genome size estimation of Haliotis Midae: estimators to assist future studies on the evolutionary history of Haliotidae
No full textThe genome size of the abalone Haliotis midae was determined using flow cytometry and calculated relative to the known genome size of the rainbow trout (Oncorhynchus mykiss). The C value for H. midae was estimated to be 1.43 pg, which is smaller in comparison with other abalone species with the same number of chromosomes (2n = 36), namely H. corrugata, 2.14 pg; H. rufescens, 1.82 pg; and H. fulgens, 1.71 pg. In these Californian abalone species, a positive correlation between C value and the number of metacentric/submetacentric chromosomes with a subsequent loss of submetacentric/subtelocentric chromosomes was observed. Karyotypic analysis in H. midae indicates 6M 10SM 2 ST (metacentric submetacentric subtelocentric) chromosome pairs, the lowest number of metacentric and the highest number of subtelocentric chromosomes when compared with the Californian species. This pattern, in the light of recent phylogenetic and cytogenetic evidence, leads us to hypothesize that during the evolution of the genus, there were some preferential karyotypic rearrangements. Research on the genome size of other abalone species in general and specifically South African species, combined with chromosome banding techniques, could provide more insight into the evolution of this genus
Transcriptome characterization of the South African abalone <it>Haliotis midae </it>using sequencing-by-synthesis
Full text linkAbstract Background Worldwide, the genus Haliotis is represented by 56 extant species and several of these are commercially cultured. Among the six abalone species found in South Africa, Haliotis midae is the only aquacultured species. Despite its economic importance, genomic sequence resources for H. midae, and for abalone in general, are still scarce. Next generation sequencing technologies provide a fast and efficient tool to generate large sequence collections that can be used to characterize the transcriptome and identify expressed genes associated with economically important traits like growth and disease resistance. Results More than 25 million short reads generated by the Illumina Genome Analyzer were de novo assembled in 22,761 contigs with an average size of 260 bp. With a stringent E-value threshold of 10-10, 3,841 contigs (16.8%) had a BLAST homologous match against the Genbank non-redundant (NR) protein database. Most of these sequences were annotated using the gene ontology (GO) and eukaryotic orthologous groups of proteins (KOG) databases and assigned to various functional categories. According to annotation results, many gene families involved in immune response were identified. Thousands of simple sequence repeats (SSR) and single nucleotide polymorphisms (SNP) were detected. Setting stringent parameters to ensure a high probability of amplification, 420 primer pairs in 181 contigs containing SSR loci were designed. Conclusion This data represents the most comprehensive genomic resource for the South African abalone H. midae to date. The amount of assembled sequences demonstrated the utility of the Illumina sequencing technology in the transcriptome characterization of a non-model species. It allowed the development of several markers and the identification of promising candidate genes for future studies on population and functional genomics in H. midae and in other abalone species.</p
Application of European standards for health and quality control of game meat on game ranches in South Africa
Full text linkCITATION: Van der Merwe, M., Jooste, P. J. & Hoffman, L. C. 2011. Application of European standards for health and quality control of game meat on game ranches in South Africa. Journal of the South African Veterinary Association, 82(3):a63, doi:10.4102/jsava.v82i3.63.The original publication is available at https://jsava.co.zaThe health and quality compliance of game carcasses (n = 295) intended for the South African export market and aspiring to comply with the strict hygiene requirements of the European Union were compared with game carcasses (n = 330) available for the local market and currently not subjected to meat safety legislation. Samples were collected in similar seasons and geographical areas in South Africa from 2006 to 2009. Aerobic plate counts (APC) of the heart blood verified that both groups possessed similar ante mortem bacterial status. For health compliance APC, tests for Escherichia coli, Salmonella spp. and Staphylococcus aureus were performed on the carcasses. Surfaces of the local carcasses were swabbed using the European Enviro-biotrace sponge technique at 3 and 72 h post mortem. Unskinned but eviscerated export carcasses in the abattoir were skinned and sampled by incision using a cork borer 72h post mortem. Temperature andpHreadings were recorded at 3 and 72 h post mortem from the longissimus dorsi muscle and the readings at 3 h differed (P = 0.035). Temperatures at 72 h were lower for export than local carcasses (P < 0.001) because of earlier introduction and maintenance of the cold chain. The pH readings also differed between groups at 3 and 72 h (P<0.001). APC results for the local group exceeded the maximum permissible count (<105). S. aureus results showed differences (P <0.001), with readings from the local group being higher. The same tendency was exhibited for E. coli (P = 0.008). Imposition of hygiene guidelines for game ranchers producing meat for the local market is therefore recommended.https://jsava.co.za/index.php/jsava/article/view/63Publisher's versio
Disulfide cross-links reveal conserved features of DNA topoisomerase I architecture and a role for the n terminus in clamp closure
No full textIn eukaryotes, DNA topoisomerase I (Top1) catalyzes the relaxation of supercoiled DNA by a conserved mechanism of transient DNA strand breakage, rotation, and religation. The unusual architecture of the monomeric human enzyme comprises a conserved protein clamp, which is tightly wrapped about duplex DNA, and an extended coiled-coil linker domain that appropriately positions the C-terminal active site tyrosine domain against the Top1 core to form the catalytic pocket. A structurally undefined N-terminal domain, dispensable for enzyme activity, mediates protein-protein interactions. Previously, reversible disulfide bonds were designed to assess whether locking the Top1 clamp around duplex DNA would restrict DNA strand rotation within the covalent Top1-DNA intermediate. The active site proximal disulfide bond in full-length Top1-clamp(534) restricted DNA rotation (Woo, M. H., Losasso, C., Guo, H., Pattarello, L., Benedetti, P., and Bjornsti, M. A. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 13767-13772), whereas the more distal disulfide bond of the N-terminally truncated Topo70-clamp(499) did not (Carey, J. F., Schultz, S. J., Sisson, L., Fazzio, T. G., and Champoux, J. J. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 5640-5645). To assess the contribution of the N-terminal domain to the dynamics of Top1 clamping of DNA, the same disulfide bonds were engineered into full-length Top1 and truncated Topo70, and the activities of these proteins were assessed in vitro and in yeast. Here we report that the N terminus impacts the opening and closing of the Top1 protein clamp. We also show that the architecture of yeast and human Top1 is conserved in so far as cysteine substitutions of the corresponding residues suffice to lock the Top1-clamp. However, the composition of the divergent N-terminal/linker domains impacts Top1-clamp activity and stability in vivo
The evolutionary spatial prisoner's dilemma on a cycle
Full text linkCITATION: Burger, A. P., Van der Merwe, M. & Van Vuuren, J. H. 2013. The evolutionary spatial prisoner's dilemma on a cycle. ORiON, 29(1):1–16, doi:10.5784/29-1-126.The original publication is available at http://orion.journals.ac.zaIn this paper we consider the Evolutionary Spatial Prisoner's Dilemma (ESPD) in which players are modelled by the vertices of a cycle representing a spatial or organisational structure amongst the players. During each round of the ESPD every pair of adjacent players in the cycle play a classical prisoner's dilemma against each other, and they update their strategies from one round to the next based on the perceived success achieved by the strategies of neighbouring players during the previous round. In this way players are able to adapt and learn from each other's strategies as the game progresses without being able to rationalise good strategies. We characterise all steady states of the game as well as the structures of those initial states that lead to the emergence of persistent substates of cooperation over time. We finally determine analytically (i.e. without using simulation) the probability that the game's states will evolve from a randomly generated initial state towards a steady state which accommodates some form of persistent cooperation. More specifically, we show that there exists a range of game parameter values for which the likelihood of the emergence of persistent cooperation increases to almost certainty as the length of the cycle increases.http://orion.journals.ac.za/pub/article/view/126Publisher's versio
Relationship building during the initial phase of social work intervention with child clients in farm communities in the Boland district
Full text linkMSW, North-West University, Potchefstroom Campus, 2014Children constitute a large part of the client group that social workers deal with on a daily basis. Establishing a helping relationship between the child client and the social worker is crucial for accurate assessments and successful interventions. In the rural areas there are limited resources for social workers and that impedes referrals for therapeutic interventions with children. The social worker is then expected to be able to intervene in order for children to deal with their problems and improve their well-being. If the social worker is unable to establish a relationship with the child client, then his/her assessments and interventions would be affected detrimentally. The literature is clear that an established helping relationship is necessary in order for social workers to be able to intervene successfully. This study endeavoured to qualitatively explore the relationship building experiences in the initial phase of social work intervention between social workers and child clients in their middle childhood years. The findings of the study showed that it is indeed a wonderful and motivating experience to be able to establish a helping relationship with a child and to be allowed to influence the child’s life. But social work is practical and sometimes has to focus on immediate needs and crisis decisions instead of solely focusing on building a helping relationship. First impressions are lasting and the helping relationship often has to be built swiftly and in difficult circumstance. There are a few major constraints to establishing the helping relationship in the initial phase of social work. Limited time and resources prevent social workers from committing to individual intervention with a child. Children are wary of social workers due to the stigma of statutory work, and building rapport is thus difficult as a result of the resistance the social worker experiences from the child client and/or his parents. Rural social workers often have to travel to the child client as the child does not have the means to come to the social worker, and these guest locations are usually not child- and/or intervention-friendly. The participants observed that the children are not familiar with play material which limits the initial relationship building activities that one can employ. An interesting experience that the social workers had, was that they withdrew from certain individual interventions with children for fear that they might worsen the child’s experience due to their lack of skills in working with children on sensitive matters. Certain professional attributes of the social workers aid the initial relationship building experience with children. It was observed that the natural appeal between the social worker and child plays a significant role in establishing the relationship and that it cannot be forced. Based on the findings of the study certain recommendations could be made towards further research in the future. Apart from discussing their experiences and constraints in relationship building during the initial phase, the children and social workers also made suggestions for practice. These suggestions were captured in guidelines for the readers of this report. Propositions are made to non-government organisations for training opportunities for social workers in the field. A few recommendations are also made to researchers who propose to do research with children as participants.Master
Psychosocial support by community health workers of children living with chronically ill family members
No full textPhD (Nursing), North-West University, Potchefstroom Campus, 2017Chronic illness has become a worldwide concern and South Africa is confronted with the quadruple burden of disease, which includes chronic illnesses and HIV/TB/maternal and perinatal conditions. Rendering support to late middle childhood children living with chronically ill family members in homes in Delft, Western Cape, became a concern that needed further investigation. These homes were accessed by 122 community health workers (CHWs) employed by an NGO funded by the Western Cape Department of Health. The CHWs were supervised by three nurses and a project manager (the researcher) to provide integrated home based care to clients in need of care and support that were referred from local health facilities. Many of these clients suffered from chronic diseases, which are diseases that last longer than three months. Late middle childhood children living in these homes had to care for the chronically ill person and appeared to be overburdened by the demands of caring, household duties, school and completion of their age-related developmental tasks. This research opportunity presented itself in this community and the researcher, as insider researcher, initiated Participatory Action Research (PAR) to gain insight into the psychosocial needs of these children. The researcher also investigated what components should form part of a support intervention.
PAR was chosen as the ideal research methodology due to its flexible, cyclic and participatory approach that required collaboration with the community to tap into local knowledge and wisdom. The research stages included i) identification of the problem, ii) literature study and planning, iii) taking action, iv) implementation, and v) evaluation. The research process included continuous reflection with co-researchers.
The entry point for this study was engagement with local stakeholders through two meetings to identify the problem. A discussion with a group of CHWs and nurse coordinators was held. Seven CHWs volunteered to become co-researchers, as the well-being of late middle childhood children was a concern to them. The main research question asked what the content of a support programme for late middle childhood children living in homes with chronically ill family members would entail. This programme was implemented by CHWs. Data collection included body mapping and drawing exercises with 22 late middle childhood children between the ages of 9 and 13 years that live in homes with chronically ill family members, 14 semi-structured interviews with families who care for chronically ill family members and a workshop with 7 adolescents that have lived in homes with a chronically ill person between the ages of 9 and 13 years. These adolescents gave a retrospective view on their situations when they were between 9 and 13 years old. The data was analysed thematically. Due regard was given to ethical considerations, and it was important to obtain consent from the participants and assent from the children. Four themes were identified to illuminate the plight of the children, namely: Physical and psychological factors that affect the children in the home; socio-economic factors detrimental to the development of late middle childhood children, availability of support systems and psychosocial needs of children that live in homes with chronically ill persons.
The results and functional elements that were identified concluded that late middle childhood children needed psychosocial support and CHWs were in the ideal position to provide such support, however, they lacked training. Six workshops were arranged with CHWs and two senior social workers to discuss the attributes required from a CHW to render psychosocial support to children. Further workshops included training the CHWs in basic counselling skills for children and the practical application of the support programme with a workbook and an activity bag as tools. The workbook was implemented by the CHWs with three late middle childhood children and refined by conducting semi-structured interviews with three other late middle childhood children to evaluate the workbook. Valuable local knowledge was harnessed from stakeholders, families, children and CHWs to obtain a practical solution to the research problemDoctora
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