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Pretoria, South Africa

Van Der Horst G.,National Zoological Gardens
Biotechnic and Histochemistry | Year: 2013

The standard method for assessing blood cell characteristics using an ocular micrometer is time-consuming and limited. We used the Nikon NIS Elements imaging software and May-Grünwald-Giemsa staining to determine whether automated image analysis is suitable for rapid and accurate quantitative morphometry of erythrocytes. Blood was collected during four seasons from 126 geometric tortoises and the blood smears were evaluated for cell (C) and nuclear (N) characteristics of the erythrocytes. We measured area, length (L), width (W), perimeter, elongation and pixelation intensity, and calculated L/W and N/C areas. Erythrocyte size differed among cohorts; females, the larger sex, had smaller erythrocytes than either males or juveniles. Males had more elongated erythrocytes than females and erythrocytes of adults were more elongated than those of juveniles. Erythrocyte size and shape influence the efficiency of gas exchange owing to surface area to volume ratios, which are greater for small, elongated cells than for large, round cells. The high N/C ratio and low pixelation intensities of males and juveniles indicate that they may have had more immature erythrocytes in their circulation than females. The use of pixelation intensity to indicate the presence of immature erythrocytes was validated by seasonal differences that corresponded to the biology of the tortoises. Pixelation intensity was lowest in winter. We found that automated image analysis is a rapid and reliable method for determining cell size and shape, and it offers the potential for distinguishing among developmental stages that differ in staining intensity. The method should be useful for rapid health assessments, particularly of threatened species, and for comparative studies among different vertebrates. © 2013 The Biological Stain Commission. Source


Osmers B.,University of Limpopo | Petersen B.-S.,University of Kiel | Hartl G.B.,University of Kiel | Grobler J.P.,University of the Free State | And 3 more authors.
Mammalian Biology | Year: 2012

We carried out a population genetic analysis of five southern African gemsbok (Oryx gazella) populations based on 530. bp of the mitochondrial control region and ten microsatellites in 75 individuals. Both markers show the high variability often observed in African bovids. Three of the populations which can be traced back to very small founding or current sizes do not show any signs of reduced variability compared to the remaining populations. The mitochondrial haplotypes form three distinct lineages which most likely originated in the Pleistocene when climate fluctuations led to periodical reduction and spreading of gemsbok habitat and which, today, are found throughout the distribution range. Bayesian microsatellite analyses yielded two groups, suggesting a more recent geographical differentiation following the admixture of the mtDNA lineages. Combining our sequences with available published data of the remaining oryx species allowed for a direct molecular comparison of O. gazella and O. beisa which have sometimes been considered a single species. The average genetic divergence between haplotypes from the two taxa was very high (39.9%), supporting their classification into two different species. © 2011 Deutsche Gesellschaft für Säugetierkunde. Source


Pfitzer S.,Magudu Veterinary Consulting Room | Last R.,Vetdiagnostix Veterinary Pathology Services | Espie I.,National Zoological Gardens | van Vuuren M.,University of Pretoria
Transboundary and Emerging Diseases | Year: 2015

Within the tribe Bovini in the subfamily Bovinae, the water buffalo (Bubalus Bubalis), American bison (Bison bison), European bison (Bubalus bonasus) and yak (Bos grunniens) are recognized as species highly susceptible to malignant catarrhal fever (MCF). In contrast, the lack of reports describing clinical MCF in the African buffalo (Syncerus caffer) whether free ranging or captive has led to a perception that African buffaloes are resistant to MCF. During the last decade, several cases of MCF in African buffaloes were confirmed in South Africa and experience with seven of these cases is described in this report. Detection of viral nucleic acid in blood or tissues was successful in six African buffaloes that suffered from clinical signs compatible with MCF. Four were positive for infection with ovine herpesvirus type 2 (the causative virus of sheep-associated MCF), and two were positive for alcelaphine herpesvirus type 1 (causative virus of wildebeest-associated MCF). Histopathological examination of tissue samples from all the animals yielded typical lesions that were consistent with those described for MCF in domestic cattle. Developments in the management of African buffaloes translocated from their traditional habitats have likely contributed to the identification of another susceptible host in the subfamily Bovinae. © 2013 Blackwell Verlag GmbH. Source


Naidoo V.,University of Pretoria | Wolter K.,Vulture Programme | Espie I.,National Zoological Gardens | Kotze A.,National Zoological Gardens | Kotze A.,University of the Free State
Journal of Zoo and Wildlife Medicine | Year: 2012

The National Zoological Gardens of South Africa (NZG) is involved in the ex situ conservation of Gyps coprotheres, the Cape Griffon vulture (CGV) and houses 24 birds in a 100-yr-old aviary. Following the death of one vulture with high liver lead concentrations, an investigation was launched to ascertain the source(s) and consequences of lead toxicity in this breeding colony. Whole blood from 24 CGV, paint from the enclosure, water, and soil sampled at various locations within the enclosure were evaluated for their lead concentration, and data were gathered from NZG's medical records. The lead concentration in the paint, water, and enclosure soil was 5,100 μg/g, 0.5 μg/dl, and 72.48 ± 21.83 μg/g, respectively. The whole-blood lead concentrations were 56.58 ± 11 μg/dl. The breeding history of six pairs within the contaminated enclosure since 2002 showed 45 eggs laid, of which 44% were infertile and 24% successfully reared. The medical records revealed evidence of osteodystrophy despite adequate nutrition. As intervention measures, six birds were treated with Ca2+EDTA and the topsoil inside the enclosure was replaced. As a result, the lead concentration in the enclosure soil dropped to14.74 ± 14.39 μg/g, and the whole-blood lead concentrations declined to 42.75 ± 11.64 μg/dl. It was concluded that lead concentrations in whole blood in excess of 100 μg/dl leads to clinical signs of lead toxicity in the CGV. Lower levels appear to interfere mainly with reproductive potential. Copyright © 2012 by American Association of Zoo Veterinarians. Source


Govender T.,Cape Peninsula University of Technology | Dawood A.,National Zoological Gardens | Esterhuyse A.J.,Cape Peninsula University of Technology | Katerere D.R.,PROMEC Unit
South African Journal of Science | Year: 2012

Antimicrobial resistance results in increased morbidity and mortality, and increased health-care costs. Therefore the need to develop new classes of antibiotics is indispensable. Antimicrobial peptides are a relatively new class of potential antibiotics which are fast acting, possess broad-spectrum activity and are able to escape many of the currently known mechanisms of drug resistance. They have been shown to be active against Gram-negative and Gram-positive bacteria, fungi, enveloped viruses and even cancer cells. However, toxicity to healthy host cells remains a concern and has affected the clinical development of therapeutics based on antimicrobial peptides. The purpose of this review is to discuss recent advances in research focused on antimicrobial peptides from frogs and the challenges in conducting research in this area in southern Africa. An extensive literature review of relevant articles published between 1980 and the present was conducted using PubMed, ScienceDirect, Sabinet, Elsevier and GoogleScholar. There has been little research done on anurans from southern Africa which are endemic to the region, and there is therefore a need to focus on this group for the purposes of bioprospecting for potentially new antimicrobial peptide compounds. © 2012. The Authors. Source

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