Publications by authors named "Irene Barnhoorn"

This paper reports on the seasonal and species comparison of hepatic nodular alterations in two indicator fish species from the hyper-eutrophic Roodeplaat Dam in South Africa. This freshwater system is characterized by seasonal cyanobacterial algal blooms which release bio-toxins, including hepato-toxins, which can have negative effects on the health of the resident fish population. A total of 115 Clarias gariepinus (Burchell) and 98 Oreochromis mossambicus (Peters) were collected seasonally across six different surveys over a period of 3 years.

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Bats have been proposed as reliable bioindicators for monitoring bioaccumulation of elements and chemicals in natural and transformed ecosystems. Non-invasive methods are becoming more popular as research moves away from destructive methodologies. We present the first concentrations of 23 elements in Mops condylurus and Tadarida aegyptiaca (Molossidae) fur and blood from an opencast diamond mine and reference area using inductively coupled plasma mass spectrometry (ICP-MS).

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Many of South Africa's freshwater impoundments are compromised by pesticide pollution, and the Roodeplaat Dam, near Pretoria, is no exception. This paper is, to the best of our knowledge, the first report of the herbicides Dacthal, metribuzin, simazine, tebuthiuron, terbuthylazine, and the fungicides azoxystrobin, carbendazim, epoxiconazole, metalaxyl (Ridomil), propiconazole, pyrimethanil and thiabendazole in a South African freshwater impoundment. This short note reports on the screening results of water and muscle tissue samples against a comprehensive library of pesticides, herbicides and fungicides in the polluted Roodeplaat Dam.

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Background: Africa faces a number of unique environmental challenges. Unfortunately, it lacks the infrastructure needed to support the comprehensive environmental studies that could provide the scientific basis to inform environmental policies. There are a number of known sources of endocrine-disrupting chemicals (EDCs) and other hazardous chemicals in Africa.

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In malaria-endemic areas, where DDT is still used for vector control by indoor residual spraying (IRS), the concentrations of DDT in human blood and breast milk are high, and there are indications of human health impacts. To identify the possible avenues of exposure reduction, we created the concept of a Total Homestead Environment Approach (THEA). THEA characterizes the interactions between DDT, humans, and the biota within and around homesteads.

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The African sharptooth catfish (Clarias gariepinus) is indigenous to South Africa where it is commonly found in calm waters such as lakes, streams, rivers, swamps and floodplains. The males of this gonochoristic species can be readily distinguished from females via a distinct elongated urogenital papilla with a pointed tip, located just behind the anus. This structure is an androgen controlled secondary sexual characteristic and could potentially be affected by chemicals displaying endocrine disrupting properties during development.

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In a previous study on the effects of gestational and lactational exposure of para-nonylphenol on male rats, we noted in both induced and uninduced rats, that variations in cleaved caspase-3 immunostaining patterns were associated with distinct nuclear alterations in mainly basally located germ cells (spermatogonia and preleptotene spermatocytes). These were re-analysed and compared with cleaved caspase-3-labeled germ cells in the aging human and the spermatogenically active catfish testis. In the rat testes, cytoplasmic immunostaining was progressively associated with lateral compression of the nucleus, its break up into large pieces which can contain immunostained marginated chromatin masses.

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This study assesses the effects of 1,1-bis (4-chlorophenyl)-2,2,2-trichloroethane (DDT) on the reproduction and gonadal histology of adult Mozambique tipalia (Oreochromis mossambicus). The fish were allowed to breed, following exposure to 2 and 5μg/l of waterborne technical-grade DDT for 40 days. Fertilized eggs were artificially incubated.

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This paper reports on the mechanistic basis of cellular death in the testis of Clarias gariepinus using the TUNEL and caspase-3 immunohistochemistry. It was also aimed to determine the testicular zone most suitable for the quantification of testicular apoptosis. The results showed that based on its immuno-expression patterns, activated caspase-3 has a clear and defined role in the progression of germ cell apoptosis in spermatogenically active catfish testis.

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