Seasonal variations of calcium and phosphorus in the juveniles of freshwater murrel,Ophicephalus punctatus Bloch

Summary In young O. punctatus seasonal variations in calcium and phosphorus showed a direct correlation. Both of these minerals showed a bimodal cycle. High values occurred during pre- and post-monsoon months and low values during winter and monsoon months. These changes seem to be related to the feeding intensity and growth of the fish.     

Dengue-virus-infected dendritic cells trigger vascular leakage through metalloproteinase overproduction

Dengue virus (DV) is an important re-emerging arthropod-borne virus of global significance. The defining characteristic of DV infection-associated pathology is haemorrhagic fever, which often leads to a fatal shock-like syndrome (DHF/DSS) owing to an increase in vascular endothelial permeability. Here, we show, in a viral dose-dependent manner, that DV-infected immature dendritic cells overproduce soluble gelatinolytic matrix metalloproteinase (MMP)-9-and to a lesser extent MMP-2-which enhances endothelial permeability, but which are reduced by specific inhibitors and a neutralizing anti-MMP-9 antibody. This permeability was associated with a loss of expression of the platelet endothelial adhesion molecule 1 (PECAM-1) and vascular endothelium (VE)-cadherin cell adhesion molecules and redistribution of F-actin fibres. These in vitro observations were confirmed in an in vivo vascular-leakage mouse model. These results provide a molecular basis for DHF/DSS that could be a basis for a general model of haemorrhagic fever-inducing viruses, and identify a new therapeutic approach for the treatment of viral-induced vascular leakage by specifically targeting gelatinolytic metalloproteases.     

More reliable estimates of divergence times in Pan using complete mtDNA sequences and accounting for population structure

Here, we report the sequencing and analysis of eight complete mitochondrial genomes of chimpanzees (Pan troglodytes) from each of the three established subspecies (P. t. troglodytes, P. t. schweinfurthii and P. t. verus) and the proposed fourth subspecies (P. t. ellioti). Our population genetic analyses are consistent with neutral patterns of evolution that have been shaped by demography. The high levels of mtDNA diversity in western chimpanzees are unlike those seen at nuclear loci, which may reflect a demographic history of greater female to male effective population sizes possibly owing to the characteristics of the founding population. By using relaxed-clock methods, we have inferred a timetree of chimpanzee species and subspecies. The absolute divergence times vary based on the methods and calibration used, but relative divergence times show extensive uniformity. Overall, mtDNA produces consistently older times than those known from nuclear markers, a discrepancy that is reduced significantly by explicitly accounting for chimpanzee population structures in time estimation. Assuming the human–chimpanzee split to be between 7 and 5 Ma, chimpanzee time estimates are 2.1–1.5, 1.1–0.76 and 0.25–0.18 Ma for the chimpanzee/bonobo, western/(eastern + central) and eastern/central chimpanzee divergences, respectively.     

Acoustic interactions between free-living mother–calf Antillean manatees,Trichechus manatus manatus

Journal of Ethology - Acoustic signalling plays a crucial role in mother–calf communication. Here, we describe the acoustic signalling of three free-living Antillean manatee mother and calf...     

Mechanism of CpG DNA Methyltransferases M.SssI and Dnmt3a Studied by DNA Containing 2-Aminopurine

Murine DNA methyltransferases Dnmt3a-CD and M.SssI from Spiroplasma methylate cytosines at CpG sites. The role of 6-oxo groups of guanines in DNA methylation by these enzymes has been studied using DNA substrates, which contained 2-aminopurine at different positions. Removal of the 6-oxo group of the guanine located adjacent to the target cytosine in the CpG site dramatically reduces the stability of the methyltransferase–DNA complexes and leads to a significant decrease in the methylation. Apparently, O6 of this guanine is involved in the recognition of CpG sites by the enzymes. Cooperative binding of Dnmt3a-CD to 2-aminopurine-containing DNA and the formation of nonproductive enzyme–substrate complexes were observed.     

B-Vitamins in root exudates of cotton

Summary Cotton field soils fromFusarium wilt-free zone (KPT) and a wilt-sick zone (PLD), and root exudates of diploid and amphidiploid strains of cotton grown in these two soils were analyzed for B-vitamins by microbiological assay technique employing X-ray mutants ofNeurospora crassa andN. sitophila.PLD soil was found to contain choline, pyridoxine,p-aminobenzoic acid, traces of biotin, and inositol. KPT soil was found to contain pyridoxine, choline, thiamine,p-aminobenzoic acid, and traces of biotin and inositol.Thiamine, biotin, pyridoxine, andp-aminobenzoic acid were found in higher amounts in the exudates of diploid cotton strains, especially K 2 and 6186.9 in KPT soil. In addition to the above, choline was also found in the exudates of diploid strains grown in PLD soil.Amphidiploid strains showed comparatively lower amounts of these vitamins in the root exudates with a few exceptions.In the inoculated series, inositol was absent in most cases and the contents of other vitamins were reduced to varying extents compared to the respective healthy controls.Part of Doctoral thesis, University of Madras.