Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied. In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –¹⁴CO₂ fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum-like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed. The results indicate some structural and functional membrane deficiencies and instability of the membranes.     

Lecithotrophic development and metamorphosis in the Indo-West Pacific brittle star Ophiomastix venosa (Echinodermata: Ophiuroidea)

Summary

The larval development of the ophiocomid ophiuroid Ophiomastix venosais described using SEM. The gastrula transforms into a uniformly ciliated early larva which progressively changes into a lecithotrophic late premetamorphic larva with a continuous bilateral ciliated band. This stage is short-lived and equivalent to a highly reduced ophiopluteus. Comparisons between O. venosa and other ophiuroid species whose development has been investigated suggest that, whatever the developmental mode (lecithotrophic or planktotrophic), a pluteus stage always occurs in ophiuroids with planktonic development. Two metamorphic stages were identified, the late metamorphic larva differing from the early one by the closure of the larval mouth. The appearance of the permanent mouth marks the end of the metamorphosis. The postlarva still possesses remnants of larval features. The transformation of the reduced ophiopluteus into a barrel-shaped metamorphic larva with transverse ciliated bands, a vitellaria larva, is followed. The possible occurrence of a unique type of metamorphic larva in non-brooding ophiuroids is discussed. Verification of this, however, needs further SEM investigations on metamorphic larva from species having “regular” planktotrophic development.     

Far Eastern mullet Mugil soiuy Basilewsky (Mugilidae, Mugiliformes): the genetic structure of populations and its change under acclimatization

The introduction of Far Eastern mullet (pilengas) in the Azov Sea in the 1970s-1980s has resulted in the formation of a self-reproducing commercial population. We have carried out a comparative population-genetic analysis of the mullet from the native (Primorye, the Sea of Japan basin) and the new (The Azov Sea basin) ranges. Genetic characteristics of three Primorye and three Azov local samples were studied using electrophoretic analysis of 15 enzymes encoded by 21 gene loci. In the Azov mullet, the initial heterozygosity characteristic of the donor population was preserved while the genotype and the allele compositions changed; the changes included a 1.9-fold reduction in the percentage of polymorphic loci and 1.5-fold reduction in the mean number of alleles per locus. The genetic differences between the Azov and the Primorye sample groups were highly significant. In the native range, no genetic differentiation among the mullet samples from different areas was found (Gst = 0.42%), whereas in the Azov Sea basin, the samples from spatially isolated populations (ecological groups) exhibited genetic differences (Gst = 1.38). The genetic divergence of the subpopulations and the excess of heterozygotes at some loci in the Azov mullet suggest selection processes that formed genetically divergent groups associated with the areas of different salinity in the new range. The salinity level is assumed to be the most probable factor of local differentiating selection during fast adaptation and naturalization of the introduced mullet.     

Far Eastern Mullet Mugil soiuy Basilewsky (Mugilidae,Mugiliformes): The Genetic Structure of Populations and Its Change under Acclimatization

The introduction of Far Eastern mullet (pilengas) in the Azov Sea in the 1970s–1980s has resulted in the formation of a self-reproducing commercial population. We have carried out a comparative population-genetic analysis of the mullet from the native (Primorye, the Sea of Japan basin) and the new (The Azov Sea basin) ranges. Genetic characteristics of three Primorye and three Azov local samples were studied using electrophoretic analysis of 15 enzymes encoded by 21 gene loci. In the Azov mullet, the initial heterozygosity characteristic of the donor population was preserved while the genotype and the allele compositions changed; the changes included a 1.9-fold reduction in the percentage of polymorphic loci and 1.5-fold reduction in the mean number of alleles per locus. The genetic differences between the Azov and the Primorye sample groups were highly significant. In the native range, no genetic differentiation among the mullet samples from different areas was found (G _st = 0.42%), whereas in the Azov Sea basin, the samples from spatially isolated populations (ecological groups) exhibited genetic differences (G _st = 1.38%). The genetic divergence of the subpopulations and the excess of heterozygotes at some loci in the Azov mullet suggest selection processes that formed genetically divergent groups associated with the areas of different salinity in the new range. The salinity level is assumed to be the most probable factor of local differentiating selection during fast adaptation and naturalization of the introduced mullet.     

Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands

The alpha3 fucosyltransferase, FucT-VII, is one of the key glycosyltransferases involved in the biosynthesis of the sialyl Lewis X (sLex) antigen on human leukocytes. The sialyl Lewis X antigen (NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential component of the recruitment of leukocytes to sites of inflammation, mediating the primary interaction between circulating leukocytes and activated endothelium. In order to characterize the enzymatic properties of the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been expressed in Trichoplusia ni insect cells. The enzyme is capable of synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from 3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors demonstrate that FucT-VII is able to synthesize both di-fucosylated and tri-fucosylated structures from mono- fucosylated precursors, but preferentially fucosylates the distal GlcNAc within a polylactosamine chain. Furthermore, the rate of fucosylation of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc. These results indicate that FucT-VII is capable of generating complex selectin ligands, in vitro , however the order of fucose addition to the lactosamine chain affects the rate of selectin ligand synthesis.