Epidemiology and risk factors associated with Anaplasma marginale infection of cattle in Peninsular Malaysia

Bovine anaplasmosis is a major concern to cattle farming in most parts of the world. Anaplasmosis negatively impacts the profitability of cattle farming by reducing the production, reproduction, and draft ability of cattle. Here, we report results from a one-year cross sectional study to determine the epidemiology and the risk factors for Anaplasma marginale infection of cattle in Peninsular Malaysia. Examination of one thousand and forty five blood samples of apparently healthy cattle from forty-three farms in all the states of Peninsular Malaysia by polymerase chain reaction (PCR) assay revealed an overall prevalence of A. marginale infection of cattle of 72.6%, showing high endemicity of this heamoprotozoan among cattle in the country. Cattle breeds, production type, herd owner, herd size, management system, farm size, farm age, prophylactic treatment against blood parasites, presence of ticks, frequency of deticking, zones, closeness to forest, closeness to waste area, closeness to human settlement and closeness to body of water were the risk factors significantly associated (P?<?0.05) with the detection of A. marginale in cattle. Results of this first molecular study on the epidemiology and risk factors for A. marginale infection of cattle from all the states of Peninsular Malaysia suggest policies and strategies for the prevention and control of the parasite to improve profitability of cattle farming in the country.     

Leishmania donovani infection differentially regulates small G‐proteins

Leishmania is a protozoan parasite that resides and replicates in macrophages and causes leishmaniasis. The parasite alters the signaling cascade in host macrophages and evades the host machinery. Small G‐proteins are GTPases, grouped in 5 different families that play a crucial role in the regulation of cell proliferation, cell survival, apoptosis, intracellular trafficking, and transport. In particular, the Ras family of small G‐proteins has been identified to play a significant role in the cellular functions mentioned before. Here, we studied the differential expression of the most important small G‐proteins during Leishmania infection. We found major changes in the expression of different isoforms of Ras, mainly in N‐Ras. We observed that Leishmania donovani infection led to enhanced N‐Ras expression, whereas it inhibited K‐Ras and H‐Ras expression. Furthermore, an active N‐Ras pull‐down assay showed enhanced N‐Ras activity. L donovani infection also increased extracellular signal–regulated kinase 1/2 phosphorylation and simultaneously decreased p38 phosphorylation. In contrast, pharmacological inhibition of Ras led to reduction in the phosphorylation of extracellular signal–regulated kinase 1/2 and enhanced the phosphorylation of p38 in Leishmania‐infected cells, which could lead to increased interleukin‐12 expression and decreased interleukin‐10 expression. Indeed, farnesylthiosalicyclic acid (a Ras inhibitor), when used at the effective level in L donovani–infected macrophages, reduced amastigotes in the host macrophages. Thus, upregulated N‐Ras expression during L donovani infection could be a novel immune evasion strategy of Leishmania and would be a potential target for antileishmanial immunotherapy.     

Determinants of wing-feather moult speed in songbirds

Wing morphology is known to strongly affect flight performance by affecting lift and drag during flight. Performance may consequently deteriorate during feather moult due to the creation of feather gaps in the wing. Since wing gap size may directly affect the extent of reduced flight capacity, rapid moult involving the creation of large feather gaps is expected to substantially impair flight compared with the small gaps induced by a slower moult. To examine the factors affecting wing-feather moult speed, we studied adults of nineteen resident or very short-distance migrant passerine species during their post-breeding moult using a model-selection framework following a phylogenetically controlled analysis. We examined the speed of wing-feather moult in relation to each species’ flight distance index that was estimated based on local foraging movements rather than on longer flights (e.g., migration), assessed by the Delphi technique of expert evaluation. Moult speed was also examined with respect to six morphometric variables: body mass, wing loading, the feather comprising the tip of the wing, aspect ratio, wing span, and wing area. Our results suggest that flight distance index is the most important factor determining the speed of wing-feather moult in songbirds. Species that regularly fly a shorter distance were found to moult quickly, and those that take relatively longer flights moult slowly. These results suggest that the aerodynamic cost of wing area reduction due to feather moult shapes the evolution of annual routine processes by dictating a slower moult speed (resulting in small wing gaps) for species that regularly fly long distances and consequently may be affected more substantially by large wing gaps compared with short distance flyers.     

Regulation of MAPKs by growth factors and receptor tyrosine kinases

Multiple growth- and differentiation-inducing polypeptide factors bind to and activate transmembrane receptors tyrosine kinases (RTKs), to instigate a plethora of biochemical cascades culminating in regulation of cell fate. We concentrate on the four linear mitogen-activated protein kinase (MAPK) cascades, and highlight organizational and functional features relevant to their action downstream to RTKs. Two cellular outcomes of growth factor action, namely proliferation and migration, are critically regulated by MAPKs and we detail the underlying molecular mechanisms. Hyperactivation of MAPKs, primarily the Erk pathway, is a landmark of cancer. We describe the many links of MAPKs to tumor biology and review studies that identified machineries permitting prolongation of MAPK signaling. Models attributing signal integration to both phosphorylation of MAPK substrates and to MAPK-regulated gene expression may shed light on the remarkably diversified functions of MAPKs acting downstream to activated RTKs.     

Transgenic expression of osteoactivin in the liver attenuates hepatic fibrosis in rats

The role of osteoactivin (OA) in liver fibrogenesis remains unclear. After feeding wild-type (WT) and OA transgenic (OA-Tg) rats a choline-deficient, L-amino acid-defined (CDAA) diet for 12 weeks, we evaluated liver fibrosis. Hepatic fibrosis and expression of alpha-smooth muscle actin protein in OA-Tg rats were reduced in comparison to WT rats. Our examination of the expression of 31,100 genes by microarray analysis identified 177 and 256 genes that were upregulated and downregulated, respectively, by at least twofold in OA-Tg rat livers in comparison to WT rat livers. Of these genes, we confirmed a significant downregulation in the expression levels of tissue inhibitor of metalloproteinase-1 and -2, type I collagen, and platelet-derived growth factor receptor-alpha and -beta in the livers of OA-Tg rats. These results indicate that transgenic OA expression attenuates the development of hepatic fibrosis in association with the suppression of specific genes involved in its pathogenesis.     

Fungal apoptosis: function, genes and gene function

Cells of all living organisms are programmed to self-destruct under certain conditions. The most well known form of programmed cell death is apoptosis, which is essential for proper development in higher eukaryotes. In fungi, apoptotic-like cell death occurs naturally during aging and reproduction, and can be induced by environmental stresses and exposure to toxic metabolites. The core apoptotic machinery in fungi is similar to that in mammals, but the apoptotic network is less complex and of more ancient origin. Only some of the mammalian apoptosis-regulating proteins have fungal homologs, and the number of protein families is drastically reduced. Expression in fungi of animal proteins that do not have fungal homologs often affects apoptosis, suggesting functional conservation of these components despite the absence of protein-sequence similarity. Functional analysis of Saccharomyces cerevisiae apoptotic genes, and more recently of those in some filamentous species, has revealed partial conservation, along with substantial differences in function and mode of action between fungal and human proteins. It has been suggested that apoptotic proteins might be suitable targets for novel antifungal treatments. However, implementation of this approach requires a better understanding of fungal apoptotic networks and identification of the key proteins regulating apoptotic-like cell death in fungi.