Behavioral Lateralization and Optimal Route Choice in Flying Budgerigars

Birds flying through a cluttered environment require the ability to choose routes that will take them through the environment safely and quickly. We have investigated some of the strategies by which they achieve this. We trained budgerigars to fly through a tunnel in which they encountered a barrier that offered two passages, positioned side by side, at the halfway point. When one of the passages was substantially wider than the other, the birds tended to fly through the wider passage to continue their transit to the end of the tunnel, regardless of whether this passage was on the right or the left. Evidently, the birds were selecting the safest and quickest route. However, when the two passages were of equal or nearly equal width, some individuals consistently preferred the left-hand passage, while others consistently preferred the passage on the right. Thus, the birds displayed idiosyncratic biases when choosing between alternative routes. Surprisingly - and unlike most of the instances in which behavioral lateralization has previously been discovered - the bias was found to vary from individual to individual, in its direction as well as its magnitude. This is very different from handedness in humans, where the majority of humans are right-handed, giving rise to a so-called ‘population’ bias. Our experimental results and mathematical model of this behavior suggest that individually varying lateralization, working in concert with a tendency to choose the wider aperture, can expedite the passage of a flock of birds through a cluttered environment.     

Selection of Arabidopsis cDNAs that partially correct phenotypes of Escherichia coli DNA-damage-sensitive mutants and analysis of two plant cDNAs that appear to express UV-specific dark repari activities

To resist terrestrial UV radiation, plants employ DNA-damage-repair/toleration (DRT) activities, as well as shielding mechanisms. Little is known about the structure and regulation of plant DRT genes. We isolated DRT cDNAs from Arabidopsis thaliana, by selecting for complementation of Escherichia coli mutants lacking all bacterial defenses against UV-light damage to DNA. These mutants are phenotypically deficient in recombinational and mutagenic toleration (RecA^–), excision repair (Uvr^–) and photoreactivation toreactivation (Phr^–). Among 840 survivors of heavily UV-irradiated (10^–7 survival) mutants harboring plasmids derived from an Arabidopsis cDNA library in the vector YES, we identified four unique plant cDNAs, designated DRT100, DRT101, DRT102, and DRT103. Drt101 and Drt102 activity were specific for UV-light damage, and complemented both UvrB^– and UvrC^– phenotypes in the dark. Apparent Uvr^– correction efficiencies were 1 to 40% for Drt101, and 0.2 to 15% for Drt102, depending on the UV fluence. Drt101 and Drt102 showed no extensive amino-acid homology with any known DNA-repair proteins. Drt100 appeared to correct RecA^–, rather than Uvr^–, phenotypes. Although the light dependence of Drt103 activity was consistent with its identification as a photoreactivating enzyme, its predicted amino-acid sequence did not resemble known photolyase sequences. The N-terminal coding sequence of Drt101 suggests that it is targeted to chloroplasts, as reported for Drt100. These cDNAs afforded only modest increases in survival during the original selection procedure. The fact that they were readily isolated nevertheless suggests that selections may be made powerful enough to overcome barriers to expression and function in bacteria, at least for cDNAs of reasonable abundance.     

STUDIES ON FUNCTIONAL AND METABOLIC ROLE OF UREA CYCLE INTERMEDIATES IN BRAIN

Abstract— The distribution of argininosuccinate synthetase, argininosuccinase and arginase, and the synthesis of urea in cerebullum. cerebral cortex and brain stem have been studied. Cerebral cortex had high levels of argininosuccinate synthetase and argininosuccinase. and a high ability to synthesize urea from aspartic acid and citrulline. Of the three regions, cerebullum had the highest arginase activity. The activities of the enzymes transamidinase and ornithine aminotransferase in the metabolism of arginine and ornithine in pathways other than urea formation have been studied in the three regions of the rat brain. The activity of creatine phosphokinase in all regions was the same: carbamylphosphatase activity was highest in cerebullum. Cerebral cortex had a high activity of aspartic acid transcarba-mylase. The brain stem, among the three regions, had the lowest activities of glutamine synthetase and glutaminase. The activities of these enzymes in the different regions are discussed in relation to urea production and the utilization of the urea cycle intermediates.
Intraperitoneal injection of high amounts of citrulline brought about a rise in the glutamine synthetase activity of cerebellum and brain stem and a rise in ornithine aminotransferase in cerebral cortex and liver. These results are discussed in relation to the mechanism of action of citrulline in alleviating the toxicity in hyperammonaemic states.     

The turnover of thiamine and its phosphate esters in rat organs

Thiamine-deficient rats were injected with [³⁵S]thiamine and the turnover of the injected radioactive thiamine and its phosphate esters was measured in brain, heart, and liver after returning the rats to a normal diet. The radioactivity per gram wet tissue, as well as the specific activity, fell to half its initial value in less than 40 hr, showing that thiamine compounds were turning over rapidly in the body under normal conditions. Furthermore, there was no difference in the rate of turnover of the individual phosphate esters of thiamine. The amount of the various phosphate esters as a percentage of the total thiamine remained the same throughout the experiment.     

Identification of MMP-1 as a putative breast cancer predictive marker by global gene expression analysis

Breast cancer is the second leading cause of cancer death for women in the United States. In 2005, about 215,000 cases of invasive breast cancer (IBC) and 50,000 cases of ductal carcinoma in situ will be diagnosed and 40,000 women will die of IBC in the US. Yet there is presently no molecular marker that can be used to detect a precancerous state or identify which premalignant lesions will develop into invasive breast cancer. Here we report the gene expression analysis of atypical ductal hyperplastic tissues from patients with and without a history of breast cancer. We identify MMP-1 as a candidate marker that may be useful for identification of breast lesions that can develop into cancer.     

Molecular characterization of tumor associated antigen in mice exposed to a hepatocarcinogen

The present investigation is aimed to identify and characterize tumor-associated antigen (TAA) in animals exposed to hepatocarcinogen. Swiss albino mice showed an enhanced expression of an approximately 58 kDa glycoprotein in liver cells upon exposure to a potential hepatocarcinogen N-nitrosodibutylamine (DBN). Carcinogenesis induction in mice was monitored by assays of -glutamyl transpeptidase (GGT), acetylcholine esterase (AChE), glutathione-S-transferase (GST) activities and the level of glutathione (GSH) in liver. DBN treated animals showed cell distortion and extensive necrosis as observed by histological examination. The over-expressed TAA was purified by ion-exchange chromatography and further characterized by SDS-PAGE. The carbohydrate contents and glycan linkage to the polypeptide backbone was analyzed by using the DIG glycan differentiation and de-glycosylation kits. The glycoprotein has glycan chains that are N-linked via asparagines to the polypeptide backbone. It was also observed that the molecule is rich in sialic acid residues with a significantly high carbohydrate to protein ratio (2:1). The over-expressed high molecular weight glycoprotein TAA was found to be highly immunogenic and could eventually be used to induce immune response in order to counter tumor regression. (Mol Cell Biochem 271: 177–188, 2005)     

A bio-ecologial study of Nuggikari lake in Dharwar,Mysore State,South India

Summary The bio-ecological conditions of a perennial piece of water, called Nuggikari lake in Dharwar, Mysore State, were investigated for one year from the view-point of regional limnology of South India. The lake is filled with rain water during the south-west monsoon and a part of the north-east monsoon season from a lateritic catchment area containing cultivated land. The inter-relationship existing between the physico-chemical variables and the biological conditions are discussed. The water is turbid and reddish during June to November when the majority of the algal organisms found is Chlorophyceae with a dominance of Desmids. Later, the water becomes pale-green to dark-green when blue-green algae become abundant in summer. The figures for albuminoid nitrogen and oxygen are then highest.     

An Immunocompetent Mouse Model of Zika Virus Infection

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In silico identification and characterization of stress and virulence associated repeats in Salmonella

So much genomic similarities yet causing different diseases, is like a paradox in Salmonella biology. Repeat is one of the probes that can explain such differences. Here, a comparative genomics approach is followed to identify and characterize repeats that might play role in adaptation and pathogenesis. Repeats are non-randomly distributed in the genomes except few typhoid causing strains. Perfect long repeats are rare compare to polymorphic ones and both are statistically consistent. Significant differences in repeat densities in stress related genes manifest its probable participation in survival and virulence. 573 and 1053 repeat loci have been identified which are exclusively associated with stress and virulent genes respectively. In Salmonella Typhi, an octameric VNTR locus is found in between acrD and yffB genes having more than 25 perfect copies across Salmonella Typhi but possesses only single copy in other serovars. This repeat can be used as a diagnostic probe for typhoid.