A histology-based fish health study on Clarias gariepinus in the Hartebeespoort Dam with the focus on reproduction

A qualitative and quantitative histological assessment was done on the liver, gills and gonads. Focus was placed on reproductive health aspects by staging the gonads according to their reproductive development and assessing the motility of activated sperm using Computer Assisted Sperm Analysis.This paper was initially delivered at the Annual Congress of the Biological Sciences Division of the South African Academy for Science and Art, ARC-Plant Protection Research Institute, Roodeplaat, Pretoria, South Africa on 01 October 2010.http://www.satnt.ac.zaam201

Psychosocial, socio-cultural, and environmental influences on mental health help-seeking among African-American men

http://dx.doi.org/10.1016/j.jomh.2012.03.00

Preliminary results on sperm motility and testicular histology of two feral fish species, Oreochromis mossambicus and Clarias gariepinus, from a currently DDT-sprayed area, South Africa

The effects of DDT and its metabolites on the reproductive health of two fish species (Clarias gariepinus and Oreochromis mossambicus) were studied using the gonadosomatic index (GSI), gonadal histology and computer assisted sperm analysis (CASA). DDT and its metabolites, DDE and DDD are endocrine disrupting chemicals posing estrogenic and anti-androgenic properties, which have detrimental effects on growth and reproduction. Although DDT was banned internationally, it is still used for Malaria vector control in areas of South Africa. Both species were sampled at a reference site, Albasini dam (AD), (outside the DDT-sprayed area, <0.01 μg L−1 of DDT) and at an exposed site, Xikundu weir (XW), in the same river ± 70 km within the DDT-sprayed area, <0.01 μg L−1 of DDT. Gill nets were used to acquire a sample size of 10 male fish per site for each species. Both testes were dissected out and the GSI calculated. Uncontaminated milt was collected and analyzed using a novel CASA system based on open source software for characterization of sperm motility parameters. Testis tissue sampled for histology was fixed in Bouins and processed according to standard methods. The sample size obtained at the reference site (AD) was O. mossambicus n = 6, C. gariepinus n = 9; and at the exposed site (XW) was O. mossambicus n = 10, C. gariepinus n = 3. The GSI results showed a lower value for O. mossambicus at XW (0.06) (n = 13) than AD (0.12) (n = 6); U = 16.0, P = 0.044. However the opposite was true for C. gariepinus. Exposure to various environmental toxicants can result in gonadal changes such as decreased GSI, morphological alterations or both. Histological assessment showed histopathological alterations to testes tissue including intersex (only in O. mossambicus) and detachment of basal membranes. The CASA results showed a decrease in parameters from the reference site (AD) to the exposed site (XW) for both species. The decrease in percent motility (% MOT) for O. mossambicus from the reference site (AD) (n = 6) to the exposed site (XW) (n = 13) was statistically significant; U = 13.0, P = 0.023. C. gariepinus from the exposed site (XW) was most affected in terms of percent motility (10.00%) and velocity (67.94 μm s−1). Detailed assessment of the environmental effects of DDT in this area seems crucial before population impacts become evident

A histology-based fish health study on <i>Clarias gariepinus</i> in the Hartebeespoort Dam with the focus on reproduction

This paper was initially delivered at the Annual Congress of the Biological Sciences Division of the South African Academy for Science and Art, ARC-Plant Protection Research Institute, Roodeplaat, Pretoria, South Africa on 01 October 2010.A qualitative and quantitative histological assessment was done on the liver, gills and gonads. Focus was placed on reproductive health aspects by staging the gonads according to their reproductive development and assessing the motility of activated sperm using Computer Assisted Sperm Analysis.http://www.satnt.ac.zaam201

Intersex inferal indigenous fresh water Oreochromis mossambicus, from various parts in the Luvuvhu River, Limpopo Province, South Africa

This study reports on intersex in Oreochromis mossambicus, an indigenous fish species inhabiting most aquatic systems throughout South Africa (SA). Male fish were collected from three sites in the Luvuvhu River, Limpopo Province, SA:Albasini Dam (AD), Nandoni Dam(ND),and Xikundu Weir(XW). The latter two sites are situated in a currently dichloro-diphenyl-trichloroethane(DDT) sprayed area. A laboratory-bred reference group (AqR) were included for a histological comparison. 48% of the fish at AD were intersex individuals compared with 63% at ND, and 58% at XW. The Aq R fish had no cases of intersex. o, p0- and p, p0-DDT and metabolites dichlorodiphenyldichloroethane (DDD) and-dichlorodi-phenyl dichloro ethylene (DDE) were detected in fat samples, indicative of contamination of the aquatic environment and subsequent exposure of fish to these chemicals. Although some of the fat samples contained levels of DDTs no association could be established between intersex and chemical contaminants in fish

User experiences of medical students with 360-degree virtual reality applications to prepare them for the clerkships

For medical students, the transition from the preclinical to the clinical phase of their curriculum (clerkships) can result in increased levels of stress and anxiety. This is partly caused by low self-perception of preparedness. By using 360° video-based virtual reality it is possible to provide learners virtual access to clinical situations ahead of time. This technique can provide active and contextual user experiences and offers opportunities to demonstrate both behavioral skills and subject knowledge. We developed two 360° video-based virtual reality applications for medical students transitioning to the clerkships. In this study, we describe the development and evaluated the user experiences. Two virtual reality applications were developed for use in a small group learning session. One of the applications is an interactive virtual tour of a hospital ward, in which learners explore the Internal Medicine ward and learn about the roles of different health care professionals and their mutual interactions. In each room, the learners listen to a voice-over and look at hotspots to gather additional information. The other application has been developed to train students in observing (un)professional behavior of healthcare providers in their daily activities. An evaluation was performed by an anonymous explorative questionnaire with open and closed questions (Likert scales) regarding the user experience and cybersickness symptoms. In our study, 171 students used the applications and completed the questionnaire. For 63% of the respondents, this was their first experience with a virtual reality headset. Qualitative analysis showed that students evaluated the learning method as realistic, informative and enjoyable. Most students evaluated virtual reality as a good (59%) or excellent (26%) tool for learning. Forty-five percent of the students experienced physical discomfort, such as nausea, dizziness, headache and disorientation. In most cases, these complaints were mild, although a small number experienced severe nausea (n = 6) or severe headache (n = 2). Students suggested several areas of improvement including increase of display resolution and decrease of ambient noise causing distraction. 360° video-based virtual reality can successfully be implemented in the medical curriculum to create a realistic learning experience to prepare students for the clerkships

Effect of prior drought and pathogen stress on Arabidopsis transcriptome changes to caterpillar herbivory

In nature, plants are exposed to biotic and abiotic stresses that often occur simultaneously. Therefore, plant responses to combinations of stresses are most representative of how plants respond to stresses. We used RNAseq to assess temporal changes in the transcriptome of Arabidopsis thaliana to herbivory by Pieris rapae caterpillars, either alone or in combination with prior exposure to drought or infection with the necrotrophic fungus Botrytis cinerea. Pre-exposure to drought stress or Botrytis infection resulted in a significantly different timing of the caterpillar-induced transcriptional changes. Additionally, the combination of drought and P. rapae induced an extensive downregulation of A. thaliana genes involved in defence against pathogens. Despite a more substantial growth reduction observed for plants exposed to drought plus P. rapae feeding compared with P. rapae feeding alone, this did not affect weight increase of this specialist caterpillar. Plants respond to combined stresses with phenotypic and transcriptional changes that differ from the single stress situation. The effect of a previous exposure to drought or B. cinerea infection on transcriptional changes to caterpillars is largely overridden by the stress imposed by caterpillars, indicating that plants shift their response to the most recent stress applied.</p