Positive selection is a general phenomenon in the evolution of abalone sperm lysin

Lysin is a 16kDa acrosomal protein used by abalone sperm to create a hole in the egg vitelline envelope (VE). The interaction of lysin with the VE is species-selective and is one step in the multistep fertilization process that restricts heterospecific (cross-species) fertilization. For this reason, the evolution of lysin could play a role in establishing prezygotic reproductive isolation between species. Previously, we sequenced sperm lysin cDNAs from seven California abalone species and showed that positive Darwinian selection promotes their divergence. In this paper an additional 13 lysin sequences are presented representing species from Japan, Taiwan, Australia, New Zealand, South Africa, and Europe. The total of 20 sequences represents the most extensive analysis of a fertilization protein to date. The phylogenetic analysis divides the sequences into two major clades, one composed of species from the northern Pacific (California and Japan) and the other composed of species from other parts of the world. Analysis of nucleotide substitution demonstrates that positive selection is a general process in the evolution of this fertilization protein. Analysis of nucleotide and codon usage bias shows that neither parameter can account for the robust data supporting positive selection. The selection pressure responsible for the positive selection on lysin remains unknown.      

Phenomenon of evolution of clonal chromosomal abnormalities in childhood acute myeloid leukemia

An analysis of chromosomal abnormalities in bone-marrow cells was performed in 116 children with diagnoses of acute myeloid leukemia (AML). The frequency of the evolution of clonal chromosomal abnormalities in AML constituted 42.3%. Quantitative abnormalities of chromosomes 8, 9, and 21, as well as the secondary structural abnormalities in the chromosomal regions 12p12, 9p22, 9q22, 9q34, 11q14–23, and 6q2, were the most abundant. Quantitative abnormalities were registered in 26.7% cases. The basic mechanism of evolution of the leukemic clone contained trisomy, deletions, and monosomy. The frequency of evolution was seven times higher in the age group of up to 2 years and twofold higher in the age group of up to 5 years. The high frequency of evolution at t(15;17)(q22;q22) was established, while its absence was revealed at inv(16)(p13q22). Patients with clonal evolution were characterized by the increased frequency of relapses and earlier death before reaching remission, which might be explained by the severe initial state of those patients. The conception of abnormalities in the evolution of the clone was proposed to occur at certain stages as follows: (1) appearance of balanced rearrangements; (2) trisomy occurrence; (3) loss of chromosomal material. The occurrence of an unbalanced genome during evolution possesses advantages in the clonal proliferate activity and may be related to its response to chemotherapy. An identity in abnormal chromosomal structure was revealed as a result of the comparison of karyotypes during diagnostics and during relapse, which could be evidence of the initial induction of some types of evolution of chromosomal abnormalities in leukemic cells in AML children by the chemical agents.     

Preparation of Chitosan Cryostructurates with Controlled Porous Morphology and Their Use as 3D-Scaffolds for the Cultivation of Animal Cells

The influence of the conditions of the formation of genipin cross-linked chitosan cryostructurates on the porous morphology and physicochemical properties of these cryostructurates and on the possibility of their use as biopolymer 3D scaffolds for tissue engineering was studied. The chitosan cryostructurates were obtained by freeze-drying a chitosan acetate solution, treating the resulting sponge with an alcohol solution of ammonia to transform the polyaminosaccharide from a salt into a chitosan-base, and then cross-linking the polymer with genipin (the molar ratios of genipin to the number of chitosan amino groups were 0.05, 0.033, and 0.02, respectively). The pore sizes, water-holding capacity, and in vitro biodegradation rate of the cryostructurates were shown to depend on the aforementioned ratio. The properties of the prepared chitosan cryostructurates, the hydrogels formed by chitosan cross-linking with genipin at positive temperatures, and the films cast from genipin-containing chitosan solutions after solvent evaporation were studied and compared. The biocompatibility of the obtained macroporous sponge materials was demonstrated using L929 mouse fibroblasts. Confocal laser microscopy showed that the cells in all of the 3D scaffolds obtained were evenly distributed; they grew and proliferated when cultured in vitro for seven days.     

The role of cGMP in extinguishing the reactions of identified neurons in the edible snail to acetylcholine

Possible role of cGMP is studied in control of extinction of snail neurones RPa4, RPa3 and LPa3 reactions to acetylcholine (ACh), applied rhythmically to neurone soma by means of microiontophoresis. It is shown that guanylate cyclase activators which raise the cGMP level in the cell--Na nitroprusside and Na azide (5,10(-4)-10(-3) mol/l)--intensify at extracellular application the extinction of inward transmembrane current and membrane depolarization in response to ACh. Suggestion is made about participation of cGMP-dependent phosphorylation of membrane proteins in control of the development rate, depth and duration of neurone cholinoreceptors short-term plasticity.     

The possibility of increasing the precision of biochemical diagnostics of Gaucher disease

Estimation of chitotriosidase activity is proposed for final diagnostics of Gaucher disease. Using this method the diagnosis has not been confirmed in one patient of 25 ones with this preliminary diagnosis. The problems of complex diagnostics of Gaucher disease are discussed.     

Regulation of posttetanic increase in choline sensitivity in Helix neurons by Na,K-pump: the role of Na/Ca-exchange and of mobilized calcium

We studied the role of Na/Ca-exchange and intracellular mobilized calcium in ouabain-mediated suppression of potentiation of cholinosensitivity of somatic membrane in Helix LPa3 and RPa3 command neurons of defensive behaviour after electrical orthodromic tetanisation of n. intestinalis. Cholinosensitivity of neurons was assessed by the amplitude of the inward current evoked by acetylcholine. Inhibitor of a Na/Ca-exchange benzamil and specific inhibitor of Ca-ATPase in endoplasmic reticulum thapsigargin prevented the development of the posttetanic potentiation (PTP). PTP did not arise and at joint action of ouabain with benzamil or thapsigargin. It was concluded that Na/Ca-exchange and mobilized calcium are involved in development of PTP of cholinosensitivity in somatic neuronal membrane and its regulation by Na,K-pump.