Biochemical taxonomy by DNA analysis

Defining how closely related a pair or a group of organisms are, is necessary both for the construction of phylogenetic trees, which constitutes the academic science of systematics, and for making practical conservation management decisions, as for example, whether it would result in deleterous genetic consequences (decreased fitness on reproductive capability) if two closely related animals e.g. blesbok, Damaliscus dorcas phillipsi, and bontebok, Damaliscus dorcas dorcas, were allowed to interbreed, in which case active steps would be required to manage the animals in an appropriate way. Reliance on traditional morphological characters to answer such questions are difficult because morphological characters change at a rate which is very poorly correlated with time, whereas the genetic differences which affect management decisions change at a progressive and generally linear rate with time (Wilson et al., 1977). In order, therefore, to try and measure such genetic differences in a more quantitative way, biologists turned to biochemical methods (two to three decades ago) and initially studied differences in protein allozymes, with considerable success (reviewed in Chapter 1). Over the last few years attention has switched to use of differences at the level of DNA, since this is the most direct biochemical measure of genetic variation, being the material of which genes are made (Wilson et al., 1977). Organelle DNA from mitochondria in animals has been widely used since it has a number of advantages compared to nuclear DNA, and is the DNA used in the studies reported here. Mitochondrial DNA accumulates single base point mutations with time, at a rate about 5 to 10 times faster than in nuclear DNA (Brown et al., 1979), which renders it the DNA of choice for comparisons between sub-species, species or genera. This project set out to establish modern biochemical methods of comparative DNA analysis and to apply these to local animal groups and so obtain objective data of both academic interest and of practical value to nature conservation problems. The major academic results are the construction of a molecular phylogeny for a major proportion of the Southern African Bovidae (Chapter 3). The family Bovidae has been one of the most difficult mammalian families to classify and there is no general agreement concerning its classification (Ansell, 1971b). Mt DNA restriction analyses were performed on 14 Southern African bovids and restriction maps constructed independently for all 14 species. Phylogenetic trees were constructed by using both distance and cladistic methods. Cladograms supported a sister status of the impala relative to the Alcelaphini and Connochaetini. Four members of the Tragelaphini remained an unresolved quadrichotomy and this would be consistent with inclusion of the eland within Tragelaphus. Distance dendograms would be consistent with a major radiation at the tribal level at the end of the Miocene. Answers to questions of specific conservation interest have been obtained with respect to several animals where conservation management requires knowledge as to how closely related certain pairs or groups of animals are. The answers relate to: ( 1) bontebok, Damaliscus dorcas dorcas vs blesbok, Damaliscus dorcas phillipsi ( Chapter 4); ( 2) African wild cat, Felis lybica vs domestic cat, Felis catus (Chapter 5) and (3) Kruger vs Addo elephant (Chapter 6). A specific request of Nature conservation authorities was to define the genetic relationship between the bontebok and the blesbok, which has conservation management relevance. The sequence divergence between the blesbok and bontebok confirmed that there is no justification in terms of genetic distance alone for applying separate specific status to the bontebok and the blesbok, but would be an appropriate value consistent with maintaining their present subspecific designation. Another request of Nature conservation authorities was to define the genetic relationship between the African wild cat and the domestic cat, since interbreeding between the two takes place where the range of the African wild cat border on those areas inhabited by man, which might effectively cause the disappearance of F.lybica (Smithers, 1983). Mt DNA restriction maps were constructed for the domestic cat, African wild cat and the European wild cat, Felis sylvestris, which was also included in our analysis. The domestic cat and African wild cat were found to have identical restriction maps emphasizing their close relationship. The domestic cat and African wild cat are therefore likely to have no preferences against inbreeding and the chances of the wild cat phenotype therefore being lost by dilution into the domestic cat is high. The sequence divergence between the African wild cat and European wild cat on the other hand, suggests that the common ancestral mt DNA of these cats existed about 650 000 years ago, indicating a more recent descent than was previously thought. A further request from conservation managers was to show the genetic difference, if any, between the Knysna and Kruger elephant herds. Mt DNA fragment size comparisons were performed on 9 elephants from the Kruger National Park and 5 elephants from the Addo Elephant National Park. All the restriction patterns found in the Addo population could be found in the Kruger population. The Addo population's results was extrapolated to the Knysna population. Therefore, genetically the Knysna population would represent a subset of the larger Kruger population. There is therefore no support from the mitochondrial studies for the Knysna and the Kruger elephant populations to be considered as different subspecies

Red U : revista de docencia universitaria

Resumen basado en el de la publicaciónTítulo, resumen y palabras clave también en inglésContiene anexoEl posgrado orientado a la formación de investigadores es una pieza angular en el desarrollo del conocimiento y las sociedades contemporáneas, aunque posee escasos instrumentos para evaluar la tutoría con énfasis en sus funciones y actividades debido a la falta de definiciones sobre el constructo denominado “tutoría en posgrado”. La tutoría en los estudios de posgrado se reconoce como un modelo de formativo personalizado que coadyuva al desarrollo de capacidades para la investigación, la práctica profesional y la incorporación a la docencia en la educación superior. No obstante este concepto debe ser ampliado para incluir a los aspectos relacionados con la socialización y la integración de los estudiantes a las comunidades epistémicas y profesionales. Por ello, se fortalecen estos atributos y se da cuenta del proceso de construcción y validación de once escalas de respuesta tipo Likert, que permiten valoran el desempeño de la tutoría en los estudios de posgrado. Las escalas fueron elaboradas con base en un modelo conceptual que integra tanto funciones formativas como las socializadoras así como aspectos interpersonales que promueven la interacción entre posgraduados y tutores. Cada escala presenta una consistencia interna aceptable. La validez de las mismas se obtuvo mediante análisis factoriales, cada escala explica más del 50% de la varianza.ES

Fall history and associated factors among adults living with HIV-1 in the Cape Winelands, South Africa : an exploratory investigation

CITATION: Berner, K., et al. 2019. Fall history and associated factors among adults living with HIV-1 in the Cape Winelands, South Africa : an exploratory investigation. Open Forum Infectious Diseases, 6(10):ofz401, doi:10.1093/ofid/ofz401.The original publication is available at https://academic.oup.com/ofidPublication of this article was funded by the Stellenbosch University Open Access Fund.Background. People with HIV-1 (PWH) exhibit a high fall incidence and increased fracture risk. As little is known about fall frequency and associated factors in PWH residing in lower-middle-income countries (LMIC), we investigated fall frequency, bone quality, and factors associated with fall history in a South African cohort. Methods. Fifty PWH without obvious predisposing factors for mobility impairments attending 2 public primary care clinics in the Western Cape region participated. Demographic, clinical, and physical performance data were collected. Falls were assessed retrospectively over 12 months. Mobility and balance were evaluated using a physical performance battery. Bone mineral density was screened using quantitative ultrasound (QUS). Associations between variables and falls grouping were analyzed using chi-square tests, t tests, and Mann-Whitney U tests, and effect sizes (ES) were calculated. Results. Thirty-four percent of PWH (median age, 36.6 years) reported falling during the past year, and 41.2% of fallers reported multiple falls. Fallers had more mobility problems (P = .013), higher fear of falling (P = .007), higher fracture history (P = .003), worse balance performance (P < .001), higher proportions of detectable viral loads (P = .021), and poorer bone quality (P = .040). Differences were of medium to large ES. Conclusions. This exploratory study is the first to show that relatively young South African PWH without obvious predisposing factors for gait and balance impairments experience falls. The observed fall-associated factors warrant further research using larger samples and longitudinal designs to ascertain fall predictors within this population.https://academic.oup.com/ofid/article/6/10/ofz401/5584296Publisher's versio

Health Benefits of Fasting and Caloric Restriction

Purpose of Review: Obesity and obesity-related diseases, largely resulting from urbanization and behavioral changes, are now of global importance. Energy restriction, though, is associated with health improvements and increased longevity. We review some important mechanisms related to calorie limitation aimed at controlling of metabolic diseases, particularly diabetes. Recent Findings: Calorie restriction triggers a complex series of intricate events, including activation of cellular stress response elements, improved autophagy, modification of apoptosis, and alteration in hormonal balance. Intermittent fasting is not only more acceptable to patients, but it also prevents some of the adverse effects of chronic calorie restriction, especially malnutrition. Summary: There are many somatic and potentially psychologic benefits of fasting or intermittent calorie restriction. However, some behavioral modifications related to abstinence of binge eating following a fasting period are crucial in maintaining the desired favorable outcomes.Current Diabetes Reports (2017), 17(12): 12

Oleanolic acid: a novel cardioprotective agent that blunts hyperglycemia-induced contractile dysfunction

Diabetes constitutes a major health challenge. Since cardiovascular complications are common in diabetic patients this will further increase the overall burden of disease. Furthermore, stress-induced hyperglycemia in non-diabetic patients with acute myocardial infarction is associated with higher in-hospital mortality. Previous studies implicate oxidative stress, excessive flux through the hexosamine biosynthetic pathway (HBP) and a dysfunctional ubiquitin-proteasome system (UPS) as potential mediators of this process. Since oleanolic acid (OA; a clove extract) possesses antioxidant properties, we hypothesized that it attenuates acute and chronic hyperglycemia-mediated pathophysiologic molecular events (oxidative stress, apoptosis, HBP, UPS) and thereby improves contractile function in response to ischemia-reperfusion. We employed several experimental systems: 1) H9c2 cardiac myoblasts were exposed to 33 mM glucose for 48 hr vs. controls (5 mM glucose); and subsequently treated with two OA doses (20 and 50 µM) for 6 and 24 hr, respectively; 2) Isolated rat hearts were perfused ex vivo with Krebs-Henseleit buffer containing 33 mM glucose vs. controls (11 mM glucose) for 60 min, followed by 20 min global ischemia and 60 min reperfusion ± OA treatment; 3) In vivo coronary ligations were performed on streptozotocin treated rats ± OA administration during reperfusion; and 4) Effects of long-term OA treatment (2 weeks) on heart function was assessed in streptozotocin-treated rats. Our data demonstrate that OA treatment blunted high glucose-induced oxidative stress and apoptosis in heart cells. OA therapy also resulted in cardioprotection, i.e. for ex vivo and in vivo rat hearts exposed to ischemia-reperfusion under hyperglycemic conditions. In parallel, we found decreased oxidative stress, apoptosis, HBP flux and proteasomal activity following ischemia-reperfusion. Long-term OA treatment also improved heart function in streptozotocin-diabetic rats. These findings are promising since it may eventually result in novel therapeutic interventions to treat acute hyperglycemia (in non-diabetic patients) and diabetic patients with associated cardiovascular complications

Gender differences in metabolic risk factor prevalence in a South African student population

CITATION: Smith, C. & Essop, M. F. 2009. Gender differences in metabolic risk factor prevalence in a South African student population. Cardiovascular Journal of Africa, 20(3), 178-182.The original publication is available at http://www.cvja.co.za/Includes bibliographyWe determined selected risk factors for the metabolic syndrome and assessed the metabolic risk status (using IDF criteria) of third-year physiology students at Stellenbosch University (88 males and 178 females). Outcome measures included anthropometry [body mass index (BMI), waist circumference, waist-to-hip ratio], blood pressure (BP), resting pulse rate, and fasting blood glucose, total cholesterol and triglyceride levels. In addition, students completed a lifestyle questionnaire. A number of gender-based differences were found, with male students displaying a greater incidence of risk factors for the metabolic syndrome: 6% of males versus 3% of females displayed a cluster of three risk factors. Twenty-five per cent of female students (but only 14% of males) exhibited waist circumferences above the accepted range, which was positively correlated, for males and females, with both systolic and diastolic BP, and in females only, also with total cholesterol levels. Male students on average exercised more than their female counterparts, but also exhibited poorer eating habits. Average blood triglyceride levels for both male and female students exceeded the accepted threshold (1.85 ± 1.62 mmol/l and 2.15 ± 1.79 mmol/l, respectively). We concluded that metabolic risk factors were evident in a much younger population than commonly expected. Moreover, the gender-specific differences observed may impact on future risk assessment and preventative measures adopted.Publisher's versio

Differential hexosamine biosynthetic pathway gene expression with type 2 diabetes

The hexosamine biosynthetic pathway (HBP) culminates in the attachment of O-linked β-N-acetylglucosamine (O-GlcNAc) onto serine/threonine residues of target proteins. The HBP is regulated by several modulators, i.e. O-linked β-N-acetylglucosaminyl transferase (OGT) and β-N-acetylglucosaminidase (OGA) catalyze the addition and removal of O-GlcNAc moieties, respectively; while flux is controlled by the rate-limiting enzyme glutamine:fructose-6-phosphate amidotransferase (GFPT), transcribed by two genes, GFPT1 and GFPT2. Since increased HBP flux is glucose-responsive and linked to insulin resistance/type 2 diabetes onset, we hypothesized that diabetic individuals exhibit differential expression of HBP regulatory genes. Volunteers (n = 60; n = 20 Mixed Ancestry, n = 40 Caucasian) were recruited from Stellenbosch and Paarl (Western Cape, South Africa) and classified as control, pre- or diabetic according to fasting plasma glucose and HbA1c levels, respectively. RNA was purified from leukocytes isolated from collected blood samples and OGT, OGA, GFPT1 and GFPT2 expressions determined by quantitative real-time PCR. The data reveal lower OGA expression in diabetic individuals (P < 0.01), while pre- and diabetic subjects displayed attenuated OGT expression vs. controls (P < 0.01 and P < 0.001, respectively). Moreover, GFPT2 expression decreased in pre- and diabetic Caucasians vs. controls (P < 0.05 and P < 0.01, respectively). We also found ethnic differences, i.e. Mixed Ancestry individuals exhibited a 2.4-fold increase in GFPT2 expression vs. Caucasians, despite diagnosis (P < 0.01). Gene expression of HBP regulators differs between diabetic and non-diabetic individuals, together with distinct ethnic-specific gene profiles. Thus differential HBP gene regulation may offer diagnostic utility and provide candidate susceptibility genes for different ethnic groupings

Trimetazidine therapy for diabetic mouse hearts subjected to ex vivo acute heart failure

CITATION: Breedt, E., Lacerda, L. & Essop, M. F. 2017. Trimetazidine therapy for diabetic mouse hearts subjected to ex vivo acute heart failure. PLoS ONE, 12(6):1-27, doi:10.1371/journal.pone.0179509.Publication of this article was funded by the Stellenbosch University Open Access Fund.The original publication is available at http://journals.plos.org/plosoneAcute heart failure (AHF) is the most common primary diagnosis for hospitalized heart diseases in Africa. As increased fatty acid β-oxidation (FAO) during heart failure triggers detrimental effects on the myocardium, we hypothesized that trimetazidine (TMZ) (partial FAO inhibitor) offers cardioprotection under normal and obese-related diabetic conditions. Hearts were isolated from 12-14-week-old obese male and female diabetic (db/db) mice versus lean non-diabetic littermates (db/+) controls. The Langendorff retrograde isolated heart perfusion system was employed to establish an ex vivo AHF model: a) Stabilization phase—Krebs Henseleit buffer (10 mM glucose) at 100 mmHg (25 min); b) Critical Acute Heart Failure (CAHF) phase–(1.2 mM palmitic acid, 2.5 mM glucose) at 20 mmHg (25 min); and c) Recovery Acute Heart Failure phase (RAHF)–(1.2 mM palmitic acid, 10 mM glucose) at 100 mmHg (25 min). Treated groups received 5 μM TMZ in the perfusate during either the CAHF or RAHF stage for the full duration of each respective phase. Both lean and obese males benefited from TMZ treatment administered during the RAHF phase. Sex differences were observed only in lean groups where the phases of the estrous cycle influenced therapy; only the lean follicular female group responded to TMZ treatment during the CAHF phase. Lean luteal females rather displayed an inherent cardioprotection (without treatments) that was lost with obesity. However, TMZ treatment initiated during RAHF was beneficial for obese luteal females. TMZ treatment triggered significant recovery for male and obese female hearts when administered during RAHF. There were no differences between lean and obese male hearts, while lean females displayed a functional recovery advantage over lean males. Thus TMZ emerges as a worthy therapeutic target to consider for AHF treatment in normal and obese-diabetic individuals (for both sexes), but only when administered during the recovery phase and not during the very acute stages.http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0179509Publisher's versio