Changes in fatty acid composition of lipid classes in developing mustard seed

Maturation of mustard (Sinapis alba) seed proceeds with a sharp decrease in the amounts of palmitic and linoleic acids in the total lipids up to 6 weeks after flowering (WAF). Concomitantly, the concentration of oleic acid increases, reaching a plateau at 4 WAF, which is followed by chain elongation of oleic acid to gadoleic and erucic acids. Compositional changes in constituent fatty acids of individual lipid classes indicate that the very long-chain monounsaturated fatty acids (C₂₀ and C₂₂), as opposed to common long-chain fatty acids (C₁₆ and C₁₈), are metabolized to triacylglycerols mainly by esterification to preformed diacylglycerols and monoacylglycerols, rather than via esterification to glycerol-3-phosphate or lysophosphatidic acids.     

Cytophotometric estimation of in situ DNA content in several species of Araceae.

A wide variation in the in situ 4C DNA content, ranging from 15.02 pg to 54.09 pg was found in thirteen genera of the family Araceae. The obligate perennial species showed greater 4C DNA values compared with the facultative perennials and annuals. A remarkable heterogeneity in 4C nuclear DNA amounts was noted among obligate perennials. Intraspecific constancy in the amount of 4C DNA was recorded. The nuclear DNA content correlated positively with chromosome size, duration of the mitotic cycle, and annual to perennial growth forms. Despite an extensive variation in DNA content among the aroids investigated, each species was distinctly characterized by its specific nuclear DNA value, indicating its usefulness in taxonomic characterization and comparison of different aroids.     

Effect of dietary beta-1,3 glucan on immune responses and disease resistance of healthy and aflatoxin B1-induced immunocompromised rohu (Labeo rohita Hamilton).

The immunostimulant beta-1,3 glucan was fed at 0.1% in feed for 7 days to healthy and aflatoxin B1 (AFB1)-induced immunocompromised fish, Labeo rohita (one of the major tropical carp species), in a 60 day trial. The effects of AFB1, glucan and their interactions on non-specific and specific immunity levels and disease resistance of fish were studied. A single intraperitoneal injection of AFB1 at 1.25 mg kg(-1) body weight) caused a significant (P < 0.05) reduction in non-specific immunity as measured through neutrophil phagocytic indices, serum bactericidal activity, and specific immunity as measured through bacterial agglutination titre against Edwardsiella tarda, as well as reduced protection against Aeromonas hydrophila challenge in comparison to control fish which were exposed neither to aflatoxin nor to glucan. Feeding of glucan to healthy fish raised the non-specific and specific immunity level and protection against bacterial infection compared with the control. Feeding of glucan to AFB1-induced immunocompromised fish for 7 days significantly raised the degree of resistance against A. hydrophila challenge and the non-specific immunity level in comparison to non-treated AFB1 exposed fish. Although feeding of glucan was able to increase specific immunity, all measured through haemagglutination titre against sheep red blood cells, and bacterial (E. tarda) agglutination titre in healthy fish in comparison to all other groups, no significant increase in specific immunity to the aflatoxin-exposed group was seen.     

Identification of a critical lysine residue at the active site in glyceraldehyde-3-phosphate dehydrogenase of Ehrlich ascites carcinoma cell. Comparison with the rabbit muscle enzyme.

The involvement of the lysine residue present at the active site of Ehrlich ascites carcinoma (EAC) cell glyceraldehyde-3-phosphate dehydrogenase (Gra3PDH) was investigated by using the lysine specific reagents trinitrobenzenesulfonic acid (TNBS) and pyridoxal phosphate (PP). Both TNBS and PP inactivated EAC cell Gra3PDH with pseudo-first-order kinetics with the rate dependent on modifier concentration. Kinetic analysis, including a Tsou plot, indicated that both TNBS and PP apparently react with one lysine residue per enzyme molecule. Two of the substrates, d-glyceraldehyde-3-phosphate and NAD, and also NADH, the product and competitive inhibitor, almost completely protected the enzyme from inactivation by TNBS. A comparative study of Gra3PDH of EAC cell and rabbit muscle indicates that the nature of active site of the enzyme is significantly different in these two cells. A double inhibition study using 5,5'-dithiobis(2-nitrobenzoic acid) and TNBS and subsequent reactivation of only the rabbit muscle enzyme by dithiothreitol suggested that a cysteine residue of this enzyme possibly reacts with TNBS. These studies on the other hand, confirm that an essential lysine residue is involved in the catalytic activity of the EAC cell enzyme. This difference in the nature of the active site of EAC cell Gra3PDH that may be related to the high glycolysis of malignant cells has been discussed.     

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     

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.