Preparation of long-chain acyl thioesters - thio wax esters - by the use of lipases

Long-chain acyl thioesters have been prepared by lipase-catalyzed thioesterification of lauric, myristic, palmitic and stearic acids with decanethiol, dodecanethiol, tetradecanethiol, hexadecanethiol and octadecanethiol. Lipase from Candida antarctica was more effective than that from Rhizomucor miehei. The extent of thioesterification increased with increasing chain length of the fatty acids and decreasing chain length of the alkanethiols. Lipase-catalyzed transthioesterification of fatty acid methyl esters with alkanethiols was less effective than thioesterification for the preparation of acyl thioesters. © Rapid Science Ltd. 1998     

Latitudinal Adh allozymic variation and ethanol tolerance in Indian populations of Drosophila melanogaster

Ten Indian geographical populations of D. melanogaster were assayed electrophoretically for Adh genic variation. The Indian geographical populations of D. melanogaster revealed significant clinal variation (3 % for 1 d? latitude) at Adh locus and Adh^F allelic frequency correlated significantly with increase in latitude. It was suggested that the abundance of secondary alcohols in the southern Indian tropical and humid environment might exert selective pressure favouring higher frequency of Adh^S allele. Patterns of ethanol utilization as well as ethanol tolerance were analyzed in larval and adult individuals of six geographical populations of D. melanogaster. Latitudinal variation in ethanol tolerance was observed in D. melanogaster populations from India. The parallel occurrence of latitudinal variation it Adh locus as well as ethanol tolerance in Indian geographical populations of D. melanogaster could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.     

Guanine nucleotide-dependent assembly of FtsZ into filaments.

FtsZ is an essential cell division protein that is localized to the leading edge of the bacterial septum in a cytokinetic ring. It contains the tubulin signature motif and is a GTP binding protein with a GTPase activity. Further comparison of FtsZ with eukaryotic tubulins revealed some additional sequence similarities, perhaps indicating a similar GTP binding site. Examination of FtsZ incubated in vitro by electron microscopy revealed a guanine nucleotide-dependent assembly into protein filaments, supporting the hypothesis that the FtsZ ring is formed through self-assembly. FtsZ3, which is unable to bind GTP, does not polymerize, whereas FtsZ2, which binds GTP but is deficient in GTP hydrolysis, is capable of polymerization.     

Substance P analogs containing alpha,alpha-dialkylated amino acids with potent anticancer activity.

Six analogs (peptides 1-6) of the potent substance P (SP) derivative known as 'Antagonist D' were synthesized by substituting constrained amino acids Aib or Acp (cycloleucine, 1-amino cyclopentane carboxylic acid) at different positions in the Antagonist D sequence: D-Arg(1)-Pro(2)-Lys(3)-Pro(4)-D-Phe(5)-Gln(6)-D-Trp(7)-Phe(8)-D-Trp(9)-Leu(10)-Leu(11)-NH(2). In the preliminary in vitro antiproliferative screening of the analogs on different human cancer cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, peptide 1 was found to be the most active. Further, peptide 1 was butanoylated (analog 5) or octanoylated (analog 6) at the N-terminus. SP analogs 1, 5, and 6 were evaluated in vivo in a xenograft model of human primary colon tumor (PTC) cell line in athymic nude mice and were found to cause tumor regression. This study investigates if the use of the constrained amino acids Aib and Acp in the designed SP analogs can retain the in vitro and in vivo anticancer activities, which could be useful in cancer therapy and drug targeting. Further, the strategy of incorporation of Aib or Acp in biologically active peptides can be exploited in determining the receptor-bound conformation and in transforming these bioactive peptides into pharmacologically useful drugs.     

Genetic-evolutionary studies on cultivated cannas

Summary Hybridization has played a dominant and decisive role in the origin of ornamental cannas. This has been made possible by the ecospecific differentiation of the parental species, which implies lack of barriers and a good deal of recombination associated with reasonably high fertility.Colour differences between species are controlled by a number of genes and their intensifiers, inhibitors, lethals, etc. From recombination in interspecific hybrids of such a wide range of genes, segregating simultaneously and involving complex segregation, arises a wide array of heterozygous genotypes with new colours and colour combinations, releasing much genetic diversity.Hybridization has also been responsible for transgressive segregation, particularly in length and breadth of staminodia and luxuriance, affecting not only plant height but also flower size. Perhaps the most important single factor responsible for the evolution of ornamental cannas has been the repeated cycles of hybridization which have led to the breakage of size and other barriers; this seems to have been exploited continuously until very large flower size was built up and combined with other useful vegetative and floral characters such as colour and number of flowers per inflorescence, extended blooming period, cold resistance, etc. The efficient vegetative propagation made fixing of the useful genotypes no problem, although they may contain a high degree of heterozygosity and sexual sterility.Along these lines, Année (hybrids between C. indica and C. glauca) and Ehemann (hybrids between C. iridiflora and C. warscwiczii) cannas came into being in 1848 and 1863 respectively. Although both were a distinct improvement over the original species, they were still relatively small-flowered and major improvements came roundabout 1868, when Crozy, Gladiolus or French Dwarf cannas (C. X generalis Bailey) were released. This group arose from hybrids and back crosses of the first two groups and contains diploids, interchange heterozygotes and autotriploids. When further intercrossing, inbreeding and selection yielded no significant improvement, new blood in the form of C. flaccida was introduced. The result was the release of Italian, Iris, Orchid or Giant flowered cannas (C. X orchiodes Bailey) in 1872. These are asynaptic seedless diploids and allo- or segmental allotriploids. By and large, Crozy cannas are the result of exploiting new genetic diversity and transgression, while Italian cannas owe their excellence to the luxuriance accompanying the introduction of C. flaccida.Next to hybridization, triploidy (14%) has been an important mechanism in the origin of cultivars with thicker, more durable and larger flower parts. The two types of triploids, autotriploids and segmental allotriploids, are distinguishable by their morphological and cytogenetical properties.It is evident that during the 44 years 1848–1892 the speed of evolution was rapid and its direction governed by the following principles of selection: increase in hardiness, reduction in height, spikes well above foliage, free flowering, erect flowers, increase in flower size, colour diversity, circular form of flowers, increase in thickness of flower parts and durability of flower, self shedding flowers, etc. The result has been the transformation of cannas from simple foliage plants to attractive ornamental flowers.It is noteworthy that selection for the two principal uses of canna not only involved different organs, but also took place in very different environments. While selection in ornamental canna was for floral parts under a temperate European climate new to Canna, that for starch involved the rhizome in its native habitat. It is interesting that the two different purposes of selection under different habitats have both ended in triploidy: in the ornamentals this has considerably enlarged the flowers, while in the starch-yielding C. edulis it has enlarged the fleshy rhizome but had a very limited effect on the flower.     

A COMPARATIVE STUDY OF THE ULTRASTRUCTURE OF MICROVILLI IN THE EPITHELIUM OF SMALL AND LARGE INTESTINE OF MICE

A comparative analysis of the fine structure of the microvilli on jejunal and colonic epithelial cells of the mouse intestine has been made. The microvilli in these two locations demonstrate a remarkably similar fine structure with respect to the thickness of the plasma membrane, the extent of the filament-free zone, and the characteristics of the microfilaments situated within the microvillous core. Some of the core microfilaments appear to continue across the plasma membrane limiting the tip of the microvillus. The main difference between the microvilli of small intestine and colon is in the extent and organization of the surface coat. In the small intestine, in addition to the commonly observed thin surface "fuzz," occasional areas of the jejunal villus show a more conspicuous surface coat covering the tips of the microvilli. Evidence has been put forward which indicates that the surface coat is an integral part of the epithelial cells. In contrast to the jejunal epithelium, the colonic epithelium is endowed with a thicker surface coat. Variations in the organization of the surface coat at different levels of the colonic crypts have also been noted. The functional significance of these variations in the surface coat is discussed.     

Infradian rhythmicity in egg production features in relation to antioxidant profiles of Rhode Island Red (RIR) birds reared at backyard in different agroclimatic zones of West Bengal during summer stress

Egg production features viz. weekly hen day and egg weight together with some stress markers were studied in RIR birds reared under backyard in different agroclimatic zones of West Bengal. Overall, weekly hen day average and egg weight in summer was 3.39 ± 0.09 and 45.13 ± 0.24 g, respectively. But the pattern of egg production in various zones is not same, as significant egg production difference (P ≤ 0.01) among zones was noticed in summer, from 26th to 37th week. There was significant (P ≤ 0.01) correlation between weekly hen day average and egg weight on 26th, 35th and 37th week (P ≤ 0.05). The observed overall level of antioxidant enzymes viz. SOD (U/g of Hb), glutathione peroxidase (GSH-Px) (μmol/L), TAS (mmol/L) and LDH (IU/L) were 0.56 ± 0.61, 565.15 ± 0.61, 1.43 ± 0.61 and 203.05 ± 0.61, respectively, irrespective of zones. It was observed that mean concentration of SOD, GHS-Px, TAS and LDH of RIR birds reared at backyard have positive association with weekly hen day average and average egg weight throughout summer stress. The current findings showed that RIR birds reared at backyard had better adaptation ability to summer stress in different agroclimatic zones of West Bengal.