Seasonal Trend of Body Protein and Growth of Chironomid Larvae

Chironomid midges technically named blood worms are known as useful live food for higher aquatic organism like fish. Present study deals with the seasonal variations of total body protein and the growth rates of chironomid larvae occurring in two water bodies of West Bengal, India. Analysis of the data revealed that the amount of body protein and the growth rate of larvae are higher during summer and monsoon. Comparative analysis of the data, indicates that the entire phenomenon depends on nutrient cycle of the water bodies which is influenced by a number of factors such as water temperature, alkalinity and soil organic carbon.     

Impact of Urbanization on House Sparrow Distribution: A Case Study from Greater Kolkata,India

House Sparrow was the most abundant bird species near human habitat until few years back. But from the mid of twentieth century, the declining trend of House Sparrow has been reported from various countries. It has already been red listed in Netherlands and UK. Researches indicate the declining trend of House Sparrow in different cities of India like Delhi, Mumbai and Bengaluru. A 3-month wide survey has been conducted to get a preliminary idea about the distributional trend of House Sparrow in greater Kolkata. Depending on nature of urbanization and human habitat, greater Kolkata, has been subdivided into four regions (Planned City, Highly dense city, Medium dense city and Low dense city regions). In high density urban region the avian density recoded was highest, although avian diversity was maximum in medium and low dense city regions and minimum in planned city. Among 20 observational units of planned city region, House Sparrow has been noticed in 6 units and crow in all units. Among 115 observational units of rest of the regions of greater Kolkata, House Sparrow was observed in 79 units and crow in 98 units. The preliminary information revealed from this survey indicates towards negative relationship between urbanization and House Sparrow population in greater Kolkata and this negative influence is maximum in planned urban region. The presence of sufficient number of House Sparrow in any region indicates environmental stability of that region. So the declining trend of House Sparrow population in greater Kolkata, particularly in planned city region, indirectly gives the evidence of serious environmental degradation.     

Amino‐acid composition after loop deletion drives domain swapping

Rational engineering of a protein to enable domain swapping requires an understanding of the sequence, structural and energetic factors that favor the domain‐swapped oligomer over the monomer. While it is known that the deletion of loops between β‐strands can promote domain swapping, the spliced sequence at the position of the loop deletion is thought to have a minimal role to play in such domain swapping. Here, two loop‐deletion mutants of the non‐domain‐swapping protein monellin, frame‐shifted by a single residue, were designed. Although the spliced sequence in the two mutants differed by only one residue at the site of the deletion, only one of them (YEIKG) promoted domain swapping. The mutant containing the spliced sequence YENKG was entirely monomeric. This new understanding that the domain swapping propensity after loop deletion may depend critically on the chemical composition of the shortened loop will facilitate the rational design of domain swapping.     

Total antioxidant potential of resinous exudates from Heliotropium species,and a comparison of the ABTS and DPPH methods

Total reactive antioxidant potential (TRAP) of resinous exudates from Heliotropium species was evaluated by measuring the bleaching of stable free radicals. The antioxidant capacity of the resinous exudates in Trolox equivalents, evaluated from the bleaching of ABTS derived radical cations, ranged from 2.0M (H. huascoense) to 5.2 M (H. stenophyllum), indicating a very high concentration of phenolic compounds. Considerably smaller values were obtained by measuring the bleaching of DPPH radicals. The ratio between the values obtained employing ABTS derived radicals and DPPH, ranged from 37 (H. megalanthum) to 4.5 (H. chenopodiaceum variety typica). The magnitude of the difference can be considered as an indication of the relative reactivity of the antioxidants present in the exudates. Similar ratios were observed when stoichiometric coefficients were evaluated for representative purified flavonoids obtained from the resinous exudates.     

The neural inductive signal is transferred to ectoblast in 1-2 h but a continued contact with mesoblast for 2-3 h is essential for neuralization in the chick area pellucida.

In the area pellucida of the chick gastrula, the Hensen's node (HN) graft must contact the competent ectoblast for at least 4 h to promote neural induction. When we removed the grafted HN after 1 to 3 h and replaced it by a non-inducing post nodal (PN) fragment, a 1-2 h contact with HN was found to be sufficient to promote neural induction. When HN graft was removed after 3 or 4 h and replaced by PN, the neural inductive response was substantially improved towards formation of archencephalic structures. Thus, our results indicate that neural induction takes place in two steps. In the first step, a contact with HN for 1-2 h is sufficient to transferthe inductive signal which is stabilized through a second step involving continued cell-cell contact with even non-inducing PN mesoblast.     

Lithium Chloride and Trypan Blue Induce Abnormal Morphogenesis by Suppressing Cell Population Growth

Full primitive streak stage chick embryos were cultured in vitro for 20 hrs and monitored every 4 hr for morphology, cell number and blastoderm area. In normal embryos, the cell population growth is exponential and correlates directly with Increasing morphological rank. The chick blastoderm area expands in two waves, one immediately after gastrulation and another after 16 hr in culture, while cell population growth is predominant between 4–16 hr. Trypan blue and LiCI inhibit cell population growth, epiboly and shaping of organ primordia. Both teratogens induce a similar spectrum of abnormalities although the severity of abnormal development is greater with LiCl for the given dose. In most abnormal embryos the cell population size and blastoderm area are inhibited most, which is detectable already after 12 hr of culture. We have established that the cell population growth, morphogenesis and area expansion constitute a parametric hierarchy with the cell population growth as the most independent parameter in regulating normal morphogenesis.     

Active-site modification of mammalian DNA polymerase beta with pyridoxal 5'-phosphate: mechanism of inhibition and identification of lysine 71 in the deoxynucleoside triphosphate binding pocket

Pyridoxal 5'-phosphate is a potent inhibitor of the DNA polymerase activity of recombinant rat DNA polymerase beta. Kinetic studies indicate that the mechanism of PLP inhibition is complex. In a lower range of PLP concentration, inhibition is competitive with respect to substrate dNTP, whereas at higher levels of PLP several forms of enzyme combine with PLP and are involved in the overall inhibition, and a possible model for these interactions during the catalytic process is suggested. Reduction of the PLP-treated enzyme with sodium [3H]borohydride results in covalent incorporation of about 4 mol of PLP/mol of enzyme, and the modified enzyme is not capable of DNA polymerase activity. The presence of dNTP during the modification reaction blocks incorporation of 1 mol of PLP/mol of enzyme, and the enzyme so modified is almost fully active. This protective effect is not observed in the absence of template-primer. Tryptic peptide mapping of the PLP-modified enzyme reveals four major sites of modification. Of these four sites, only one is protected by dNTP from pyridoxylation. Sequence analysis of the tryptic peptide corresponding to the protected site reveals that it spans residues 68-80 in the amino acid sequence of the enzyme, with Lys 71 as the site of pyridoxylation. These results indicate that Lys 71 is at or near the binding pocket for the dNTP substrate.     

A Eudesmanolide and a guaianolide from Cyathocline purpurea

Two new sesquiterpene lactones, the eudesmanolide, isoivangustin, and the guaianolide, 6α-hydroxy-4(14),10(15)-guaianadien-8α,12-olide, have been isolated from Cyathocline purpurea.     

Genome analysis: A new approach for visualization of sequence organization in genomes

In this article we describe and demonstrate the versatility of a computer program, GENOME MAPPING, that uses interactive graphics and runs on an IRIS workstation. The program helps to visualize as well as analyse global and local patterns of genomic DNA sequences. It was developed keeping in mind the requirements of the human genome sequencing programme, which requires rapid analysis of the data. Using GENOME MAPPING one can discern signature patterns of different kinds of sequences and analyse such patterns for repetitive as well as rare sequence strings. Further, one can visualize the extent of global homology between different genomic sequences. An application of our method to the published yeast mitochondrial genome data shows similar sequence organizations in the entire sequence and in smaller subsequences