University of Johannesburg

About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Context (language use). The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

Tourism Governance and Attainment of the Sustainable Development Goals in Africa

Abstract: Inclusiveness that improves tourism governance is significant for development if benefits from tourism are distributed equitably. Declaration of 2017 as the International Year of Sustainable Touris...

Dental ontogeny in pliocene and early pleistocene hominins.

Abstract: Until recently, our understanding of the evolution of human growth and development derived from studies of fossil juveniles that employed extant populations for both age determination and comparison. This circular approach has led to considerable debate about the human-like and ape-like affinities of fossil hominins. Teeth are invaluable for understanding maturation as age at death can be directly assessed from dental microstructure, and dental development has been shown to correlate with life history across primates broadly. We employ non-destructive synchrotron imaging to characterize incremental development, molar emergence, and age at death in more than 20 Australopithecus anamensis, Australopithecus africanus, Paranthropus robustus and South African early Homo juveniles. Long-period line periodicities range from at least 6–12 days (possibly 5–13 days), and do not support the hypothesis that australopiths have lower mean values than extant or fossil Homo. Crown formation times of australopith and early Homo postcanine teeth fall below or at the low end of extant human values; Paranthropus robustus dentitions have the shortest formation times. Pliocene and early Pleistocene hominins show remarkable variation, and previous reports of age at death that employ a narrow range of estimated long-period line periodicities, cuspal enamel thicknesses, or initiation ages are likely to be in error. New chronological ages for SK 62 and StW 151 are several months younger than previous histological estimates, while Sts 24 is more than one year older. Extant human standards overestimate age at death in hominins predating Homo sapiens, and should not be applied to other fossil taxa. We urge caution when inferring life history as aspects of dental development in Pliocene and early Pleistocene fossils are distinct from modern humans and African apes, and recent work has challenged the predictive power of primate-wide associations between hominoid first molar emergence and certain life history variables.

Histopathological alterations in the liver of the sharptooth catfish Clarias gariepinus from polluted aquatic systems in South Africa

Abstract: There is a need for sensitive bio-monitoring tools in toxicant impact assessment to indicate the effect of toxicants on fish health in polluted aquatic ecosystems. Histopathological assessment of fish tissue allows for early warning signs of disease and detection of long-term injury in cells, tissues, or organs. The aim of this study was to assess the degree of histopathological alterations in the liver of C. gariepinus from two dams in an urban nature reserve, (Gauteng, South Africa). Two dams (Dam 1 and Dam 2) were chosen for their suspected levels of toxicants. Water and sediments were sampled for metal and potential endocrine disrupting chemical analysis. A quantitative and qualitative histology-based health assessment protocol was employed to determine the adverse health effects in fish. The analysis of blood constituents, fish necropsy, calculation of condition factors, and hepatosomatic indices were employed to support the findings of the qualitative and quantitative histological assessment of liver tissue. Assessment of the liver tissue revealed marked histopathological alterations including: structural alterations (hepatic cord disarray) affecting 27% of field specimens; plasma alterations (granular degeneration 98% and fatty degeneration 25%) of hepatocytes; an increase in melanomacrophage centers (32%); hepatocyte nuclear alterations (90%); and necrosis of liver tissue (14%). The quantitative histological assessment indicated that livers of fish collected from Dam 1 were more affected than the fish livers collected from Dam 2.