Bluetongue: a historical and epidemiological perspective with the emphasis on South Africa

ABSTRACT: Bluetongue (BT) is a non-contagious, infectious, arthropod transmitted viral disease of domestic and wild ruminants that is caused by the bluetongue virus (BTV), the prototype member of the Orbivirus genus in the family Reoviridae. Bluetongue was first described in South Africa, where it has probably been endemic in wild ruminants since antiquity. Since its discovery BT has had a major impact on sheep breeders in the country and has therefore been a key focus of research at the Onderstepoort Veterinary Research Institute in Pretoria. Several key discoveries were made at this Institute, including the demonstration that the aetiological agent of BT was a dsRNA virus that is transmitted by Culicoides midges and that multiple BTV serotypes circulate in nature. It is currently recognized that BT is endemic throughout most of South Africa and 22 of the 26 known serotypes have been detected in the region. Multiple serotypes circulate each vector season with the occurrence of different serotypes depending largely on herd -immunity. Indigenous sheep breeds, cattle and wild ruminants are frequently infected but rarely demonstrate clinical signs, whereas improved European sheep breeds are most susceptible. The immunization of susceptible sheep remains the most effective and practical control measure against BT. In order to protect sheep against multiple circulating serotypes, three pentavalent attenuated vaccines have been developed. Despite the proven efficacy of these vaccines in protecting sheep against the disease, several disadvantages are associated with their use in the field.     

Immunolocalization of MMP-19 in the human intervertebral disc: implications for disc aging and degeneration

Matrix metalloproteinases (MMPs) degrade components of the extracellular matrix of the disc, but the presence of MMP-19 has not been explored. In other tissues, MMP-19 is known to act in proteolysis of the insulin-like growth factor (IGF) binding protein-3, thereby exposing this protein to make it available to influence cell behavior. MMP-19 also has been shown to inhibit capillary-like formation and thus play a role in the avascular nature of the disc. Using immunohistochemistry, normal discs from six subjects aged newborn through 10 years and 20 disc specimens from control donors or surgical patients aged 15-76 (mean age 40.2 years) were examined for immunolocalization of MMP-19; six Thompson grade I discs, five Thompson grade II, eight Thompson grade III, five Thompson grade IV, and one Thompson grade V discs were analyzed. The results indicate that in discs from young subjects, MMP-19 was uniformly localized in the outer annulus. In discs from adult donors and surgical patients, outer and inner annulus cells only occasionally showed MMP-19 localization. The greatest expression of MMP-19 was observed in young discs, and little expression was seen in older or degenerating discs. Because MMP-19 has been shown to regulate IGF-mediated proliferation in other tissues, its decline in the aging/degenerating disc may contribute to the age-related decrease in disc cell numbers.     

Basic fibroblast growth factor modulates the expression of glycophorin A and c-kit and inhibits erythroid differentiation in K562 cells.

Basic fibroblast growth factor (bFGF) is produced by bone marrow stromal cells as well as by normal and leukemic hematopoietic cells. In this study, we examine the direct effects of bFGF on erythroid differentiation in K562 cells in order to determine whether bFGF can promote the expression of a primitive phenotype. Low levels of bFGF inhibited erythroid differentiation as evidenced by decreased expression of glycophorin A and increased expression of c-kit. bFGF also increased both the numbers and the sizes of colonies of K562 cells in soft agar assays. The addition of TGF-beta to these cells induced erythroid differentiation which resulted in an increase in glycophorin A and a decrease in c-kit. The simultaneous addition of bFGF and TGF-beta to K562 cells prevented both the TGF-beta-mediated increase in glycophorin A expression and the decrease in c-kit expression associated with erythroid differentiation. bFGF antagonised the TGF-beta-mediated promotion of erythroid differentiation in K562 cells in a dose dependent manner and these two cytokines counteracted each other on an approximately molar basis. These results indicate that bFGF alone increases expression of c-kit and promotes a primitive phenotype in K562 cells. In addition, bFGF counteracts the effects of differentiation-inducing cytokines, such as TGF-beta, on hematopoietic cells. It is therefore possible that enhanced production of bFGF by leukemic cells could contribute to their neoplastic phenotype by opposing the effects of negative regulators or cytokines that induce differentiation.     

Meteorological weather station data can be used in climate matching studies of biological control agents

Meteorological weather station data are often used in climate matching studies to predict potential distributions of biological control agents, yet, this does not take into account the effects of microclimates experienced by the agents. Comparisons of the number of generations that the mirid, Eccritotarsus catarinensis, a biological control agent of water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub (Pontederiaceae), was predicted to complete using meteorological weather station data, on site air temperature and water hyacinth canopy microclimate temperatures recorded over two years showed that there were no significant differences between the temperature data sources. Therefore, meteorological weather station data used in degree-day models of biological control agents are useful in explaining broad establishment patterns.     

Local Scale Comparisons of Biodiversity as a Test for Global Protected Area Ecological Performance: A Meta-Analysis

Terrestrial protected areas (PAs) are cornerstones of global biodiversity conservation. Their efficacy in terms of maintaining biodiversity is, however, much debated. Studies to date have been unable to provide a general answer as to PA conservation efficacy because of their typically restricted geographic and/or taxonomic focus, or qualitative approaches focusing on proxies for biodiversity, such as deforestation. Given the rarity of historical data to enable comparisons of biodiversity before/after PA establishment, many smaller scale studies over the past 30 years have directly compared biodiversity inside PAs to that of surrounding areas, which provides one measure of PA ecological performance. Here we use a meta-analysis of such studies (N = 86) to test if PAs contain higher biodiversity values than surrounding areas, and so assess their contribution to determining PA efficacy. We find that PAs generally have higher abundances of individual species, higher assemblage abundances, and higher species richness values compared with alternative land uses. Local scale studies in combination thus show that PAs retain more biodiversity than alternative land use areas. Nonetheless, much variation is present in the effect sizes, which underscores the context-specificity of PA efficacy.     

Isolation and sequence analysis of P450 genes from a pyrethroid resistant colony of the major malaria vector Anopheles funestus.

Pyrethroid resistance has been demonstrated in populations of Anopheles funestus from South Africa and southern Mozambique. Resistance is associated with elevated P450 monooxygenase enzymes. In this study, degenerate primers based on conserved regions of Anopheles gambiae P450 CYP4, 6 and 9 families were used to amplify genomic and cDNA templates from A. funestus. A total of 12 CYP4, 12 CYP6 and 7 CYP9 partial genes have been isolated and sequenced. BLAST results revealed that A. funestus P450s generally have a high sequence identity to A. gambiae with above 75% identity at the amino acid level. The exception is CYP9J14. The A. gambiae P450 showing highest identity to CYP9J14 exhibits only 55% identity suggesting that CYP9J14 may have arisen from a recent duplication event. Molecular phylogenetic analysis based on amino acid sequences also supported this hypothesis. Intron positions, but not size, were highly conserved between the two species. The high level of orthology that exists in the P450 gene families of these two species may facilitate the prediction of individual P450 protein function.     

Predicting the distribution of Eccritotarsus catarinensis, a natural enemy released on water hyacinth in South Africa

Water hyacinth [Eichhornia crassipes (Mart.) Solms (Pontederiaceae)] is the most damaging aquatic weed in South Africa, where five arthropod biological control agents have been released against it. The most recent introduction of Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae) has failed to establish permanent populations at a number of sites in South Africa where water hyacinth is a problem. Cold winter temperatures at these sites are assumed to be the reason for these establishment failures. This assumption was tested by investigating the thermal physiology of the mirid, then incorporating these data into various predictive distribution models. Degree‐day models predict 3–14 generations per year at different localities in South Africa, and five generations at a Johannesburg site where the mirid failed to overwinter. The inability to develop sufficiently rapidly during winter months may hinder overwintering of this insect, which was predicted to develop through only one generation during the winter months of April to August in Johannesburg. A CLIMEX model also showed that cold stress limits the mirid's ability to overwinter in the interior of the country, while determination of the lower lethal limit (–3.5 °C) and critical thermal minimum (1.2 ± 1.17 °C) also indicated that extreme temperatures will limit establishment at certain sites. It is concluded that E. catarinensis is limited in its distribution in South Africa by low winter temperatures.     

American and korean ginseng tissue cultures: Growth,chemical analysis,and plantlet production

Summary Roots, stems, or leaves of American (Panax quinquefolium) and Korean (Panax ginsing) ginseng were grown as callus or supension tissue cultures. Tissue cultures ofP. ginseng would occasionally form plantlets. The fundamental chemical composition, inorganic analysis, and saponin (panaquilin) content of American and Korean ginseng plants and tissue cultures were determined. The crude saponin content is very similar to, but approximately one-half (1.3%, fresh weight) of that present in ginseng roots. Two-dimensional thin layer chromatographic analysis revealed minor differences in the panaquilins present in American and Korean ginseng tissue cultures. The sapogenin, panaxadiol, was isolated from Korean ginseng callus.