Compounds similar to acyclovir. III. Synthesis of acyclic analogs of 5'-deoxynucleosides

A convenient method has been proposed for the synthesis of 1,2-dihydroxy-4-oxahex-3-yl and 1-hydroxy-4-oxahex-3-yl derivatives of guanine, adenine, thymine and cytosine, acyclic nucleoside analogues lacking the 3'--4' bond.     

Chlorophyll content and factors affecting its spatial distribution in the Middle Volga reservoirs

On the basis of the data obtained during field observations in the summer low water period of 2001, the patterns of chlorophyll distribution and its relation to hydrological and hydrochemical factors in two eutrophic reservoirs of the Middle Volga are studied. The hydrological structure of the Gorky Reservoir, where the Volga water mass dominates, is homogeneous, while in the Cheboksary Reservoir along with the eutrophic Volga waters, the mesotrophic Oka water masses can be distinguished keeping their abiotic and biotic features over a long distance. Phytoplankton in the two contiguous reservoirs with different flow regimens and anthropogenic loads responds differently to the external influence. An autotrophic community in the Gorky Reservoir is more stable and depends little on abiotic factors which account for ∼63% of the explained chlorophyll variation. In the Cheboksary Reservoir under maximal for the Volga cascade flow velocity and anthropogenic load, the development and distribution of phytoplankton are almost completely (R ² = 0.93) controlled by these factors. The trophic state of the reservoirs has not changed as compared to the beginning of the 1990s.     

Human parthenogenetic stem cells produce enriched populations of definitive endoderm cells after trichostatin A pretreatment

Human parthenogenetic stem cells (hpSC) hold great promise as a source of pluripotent stem cells for cell-based transplantation therapy due to their ethical method of derivation as well as the enhanced capacity for immunomatching with significant segments of the human population. We report here the directed differentiation of hpSC to produce enriched populations of definitive endoderm. Moreover, we find that treatment of undifferentiated hpSC by trichostatin A (TSA) before applying the directed differentiation protocol significantly increases the proportion of definitive endoderm cells in the final population. TSA-pretreated as well as non-TSA-treated hpSC undergoing differentiation toward definitive endoderm demonstrate a similar temporal sequence of gene expression to that which occurs in the course of definitive endoderm differentiation during vertebrate gastrulation and for differentiation of hESCs to definitive endoderm. Creation of the definitive endoderm lineages from hpSC represents the critical first step toward the development of hpSC-based cellular therapies for diseases of the liver or pancreas.     

Improved efficient gene transfer into insect and mammalian cells by baculovirus vectors

The fragments of genomics DNA of the nuclear polyhedrosis virus (NPV) containing genes of late viral proteins p10, p35, p39, were cloned, the promoter regions of this genes were used to design baculovirus transfer vectors. A double-promoter and triple-promoter baculovirus transfer vectors were obtained. Recombinant baculovirus vectors containing mammalian expression cassette with cytomegalovirus (CMV) promoter, the gene for green or red fluorescent protein, SV40pA and polylinker MCS were constructed for the delivery of foreign genes into mammalian cells.     

Compounds similar to acyclovir. II. Synthesis of acyclic analogs of 2'-deoxynucleosides

Acyclic analogues of nucleosides, viz.9- and 3-(1,6-dihydroxy-4-oxahex-3-yl)adenine, 9-(1,6-dihydroxy-4-oxahex-3-yl)guanine, 1-(1,6-dihydroxy-4-oxahex-3-yl)cytosine and thymine, with C3'-C4' bond of the furanose ring cleaved, have been prepared by condensation of trimethylsilyl derivatives of nucleic acid bases with 1,4,6-triacetoxy-3-oxahexane in the presence of Lewis acids followed by treatment with metanolic ammonia.