Synthesis of Poly(ADP-ribose) Monomer Containing 2'-O-α-D-Ribofuranosyl Adenosine

In this article, the earlier reported procedure for the synthesis of 2'-O-β-D-ribofuranosyl nucleosides was extended to the synthesis of 2'-O-α-D-ribofuranosyl adenosine, a monomeric unit of poly(ADP-ribose). It consists in condensation of a small excess of 1-O-acetyl-2,3,5-tri-O-benzoyl-α,β-D-arabinofuranose activated with tin tetrachloride with 3',5'-O-tetra-isopropyldisiloxane-1,3-diyl-ribonucleosides in 1,2-dichloroethane. The following debenzoylation and silylation of arabinofuranosyl residue and inversion of configuration at C-2'' atom of arabinofuranosyl residue and final removal of silyl protective groups gave 2'-O-α-D-ribofuranosyl adenosine in overall 13% to 21% yield. © 2019 by John Wiley & Sons, Inc.

Novel group of tyrosyl-DNA-phosphodiesterase 1 inhibitors based on disaccharide nucleosides as drug prototypes for anti-cancer therapy

A new class of tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibitors based on disaccharide nucleosides was identified. TDP1 plays an essential role in the resistance of cancer cells to currently used antitumour drugs based on Top1 inhibitors such as topotecan and irinotecan. The most effective inhibitors investigated in this study have IC50 values (half-maximal inhibitory concentration) in 0.4-18.5 µM range and demonstrate relatively low own cytotoxicity along with significant synergistic effect in combination with anti-cancer drug topotecan. Moreover, kinetic parameters of the enzymatic reaction and fluorescence anisotropy were measured using different types of DNA-biosensors to give a sufficient insight into the mechanism of inhibitor's action.

Disaccharide pyrimidine nucleosides and their derivatives: a novel group of cell-penetrating inhibitors of poly(ADP-ribose) polymerase 1

Nearly 30 synthetic nucleosides were tested with human recombinant poly(ADP-ribose) polymerase 1 as potential inhibitors of this enzyme. The most active compounds were some disaccharide analogues of thymidine: 3'-O-β-D-ribofuranosyl-5-iodo-dUrd (2d; IC₅₀ = 45 μM), 3'-O-β-D-ribofuranosyl-2'-deoxythymidine (2e; IC₅₀ = 38 μM), and 3'-O-β-D-ribofuranosyl-2'-deoxythymidine oxidized (4; IC₅₀ = 25 μM). These compounds also reduced H₂O₂-induced synthesis of poly(ADP-ribose) in cultured human ovarian carcinoma (SKOV-3) cells in a dose-dependent manner. Furthermore, compounds 2d or 2e until a concentration of 1 mM did not affect growth of SKOV-3 cells, whereas dialdehyde compound 4, as well as thymidine, exhibited a significant cytotoxicity.

[Genetic diversity of Anser albifrons Scopoli, 1769 and Anser fabalis Latham, 1787 in the Russian Far East]

Using RAPD PCR analysis and sequencing of the 5' end segment of the mtDNA control region, the genetic diversity and differentiation of Far Eastern populations of greater white-fronted goose Anser albifrons Scopoli, 1769 and bean goose Anser fabalis Latham, 1787 were examined. Based on RAPD PCR data, the level of gene diversity (h) for A. albifrons (0.3634) and A. fabalis (0.3899) was calculated. Sequence data showed considerably higher level of inter-population diversity in A. fabalis (26.4%), compared to A. albifrons (1.88%). Similarly, the nucleotide and haplotype diversity parameters were somewhat higher in A. fabalis (0.01852 and 0.955). Phylogenetic reconstructions generated using neighbor-joining and maximum parsimony algorithms divided each of the examined species into two clusters that differ in the number of haplotypes included. These clusters can correspond to the subspecies that live in the Far East.

[Phylogeography of the mallard Anas platyrhynchos from Eurasia inferred from sequencing of the mtDNA control region]

Phylogenetic relationships, demographic history, and geographic distribution of the mtDNA haplotypes of the mallard Anas platyrhynchos were examined in three populations, Indian, Northern European, and Far Eastern. Two divergent haplotype groups, A and B, were found in the Far Eastern population, while haplotypes identified in Northern European and Far Eastern populations were exclusively of the A group. The presence of B group haplotypes in the Far Eastern population can be explained either in terms of hybridization of the mallard with spot-billed duck Anas zonorhyncha at the south of the Russian Far East, or by the mtDNA paraphyly in mallards. In general, mallards from Eurasia were characterized by low genetic population differentiation along with slightly expressed phylogeographic structure. The most differentiated was the population from India (Phi(st) = 0.076-0.077), while the difference between Northern European and Far Eastern populations was extremely low (Phi(st) = 0.0029). Differentiation of Anas platyrhynchos Indian population was determined by the fact that a part of the population, inhabiting southern and eastern coasts of the Hindustan Peninsula, was resident.

[Genetic structure of the Far Eastern population of Eurasian wigeon Anas penelope inferred from sequencing of the mitochondrial DNA control region]

Sequence variation of the 5' end of the mitochondrial DNA control region (600 bp) was examined in the population samples of Eurasian wigeon Anas penelope from Anadyr' and Primorye. A total of 11 different mtDNA haplotypes were identified, with one of these belonging to American wigeon Anas americana. The presence of the mtDNA haplotype from the species closely relative to A. penelope in the Anadyr' sample can be considered as the genetic evidence in favor of interspecific hybridization. This suggestion is in the good agreement with ornithological data. Genetic differentiation of the Primorye and Anadyr' populations was low (phi(ST) = 0.096). The phylogeographic structure was not pronounced.

[Disaccharide nucleosides, an important group of natural compounds]

Main structural features of important group of natural compounds disaccharide nucleosides are reviewed. The preparation and properties of modified oligonucleotides on their basis and incorporation of reactive groups are summarized. Several examples of the use of the obtained compounds for investigation of enzymes of nucleic acids methabolism are given.

Movements of birds and avian influenza from Asia into Alaska

Despite involvement of large numbers of birds, the delivery rate of Asian-origin viruses to North America through Alaska is apparently low.

Asian-origin avian influenza (AI) viruses are spread in part by migratory birds. In Alaska, diverse avian hosts from Asia and the Americas overlap in a region of intercontinental avifaunal mixing. This region is hypothesized to be a zone of Asia-to-America virus transfer because birds there can mingle in waters contaminated by wild-bird–origin AI viruses. Our 7 years of AI virus surveillance among waterfowl and shorebirds in this region (1998–2004; 8,254 samples) showed remarkably low infection rates (0.06%). Our findings suggest an Arctic effect on viral ecology, caused perhaps by low ecosystem productivity and low host densities relative to available water. Combined with a synthesis of avian diversity and abundance, intercontinental host movements, and genetic analyses, our results suggest that the risk and probably the frequency of intercontinental virus transfer in this region are relatively low.

Phylogeography of The Mallard (Anas Platyrhynchos): Hybridization, Dispersal, and Lineage Sorting Contribute to Complex Geographic Structure

Population genetic variation in Mallards (Anas platyrhynchos; n = 152) from Western Russia, North Asia, the Aleutian Islands, and mainland Alaska was investigated using 667 base pairs of the 5′-end of the mitochondrial DNA (mtDNA) control region. DNA sequencing revealed two clades that correspond to Avise et al.’s (1990) group A and B mtDNA haplotypes. Group A haplotypes (80.3%) were wide- spread in all localities from Western Russia to Alaska. Group B haplotypes (19.7%), by contrast, were found primarily in mainland Alaska, where they occurred at high frequency (77.4%), but they also occurred at low frequencies (declining east to west) in the Aleutian Islands (11.8%) and the Primorye region of North Asia (4.4%). Group B haplotypes were not observed in Western Russia or elsewhere in North Asia outside Primorye. Consequently, Mallards exhibited substantial genetic structure between Old World and New World (ΦST = 0.4112–0.4956) but possessed little genetic structure within the Old World continental area (ΦST = 0.0018). Nonetheless, when only group A haplotypes were included in the analysis, Mallards from the Aleutian Islands differed (albeit with low levels of divergence) from each of the other three sampled regions in the Old World and New World (ΦST = 0.0728–0.1461, P < 0.05). Mallards inhabit the Aleutian Islands year-round, so these insular populations may be isolated from Asian and North American populations that occur in the Aleutian Islands only during migration. Overall weak phylogeographic structure and low genetic differentiation within Asia, and between Asia and North America when only group A haplotypes were evaluated, is probably explained by large long-term population sizes and significant intra-continental dispersal. The coexistence and nonrandom distribution of two divergent mtDNA haplotype lineages in Alaska, the Aleutian Islands, and the Primorye region of North Asia, but not in Western Russia or elsewhere in North Asia, is consistent with historical and contemporary hybridization and incomplete sorting of A and B mtDNA haplotype lineages in Mallards and closely related species inhabiting the Old World and New World.

Asymmetric Hybridization and Sex-Biased Gene Flow Between Eastern Spot-Billed Ducks (Anas Zonorhyncha) and Mallards (A. Platyrhynchos) in the Russian Far East

The Eastern Spot-billed Duck (Anas zonorhyncha) historically was rare in the southern Russian Far East. However, during the last 60–70 years, its breeding range in East Asia has expanded northwest; Eastern Spot-billed Ducks are breeding increasingly within the range of Mallards (A. platyrhynchos). We collected 120 Eastern Spot-billed Ducks and Mallards from Primorye, Russia, and sequenced 666–667 base pairs (bp) of the maternally inherited mitochondrial DNA (mtDNA) control region and 255 bp of the ornithine decarboxylase intron six (ODC6). Control region and ODC-6 allele sequences revealed two divergent groups of haplotypes and alleles that differ by 1.5% and 2.0%, respectively, and correspond to Avise et al.'s (1990) group A and B mtDNA haplotypes. Group A mtDNA haplotypes occurred in 22 Eastern Spot-billed Ducks and 78 Asian Mallards, and group B haplotypes occurred in 14 Eastern Spot-billed Ducks and 4 Asian Mallards. Moreover, the group B haplotypes that we observed predominantly in Eastern Spot-billed Ducks (i.e. group SB) were monophyletic and diverged by 2–16 substitutions from group B haplotypes previously sequenced from 241 Mottled (A. fulvigula), American Black (A. rubripes), and Mexican ducks (A. diazi), and from North American Mallards. In contrast, type 1 and 2 ODC-6 allele frequencies for Eastern Spot-billed Ducks and Mallards did not differ, but heterozygosity for the former was greater than expected under Hardy-Weinberg equilibrium. Our analysis is the first to document the existence of two divergent haplotype and allele lineages (group A and B, type 1 and 2) in Asian mallard species and suggests that Eastern Spot-billed Ducks are more closely related to North America's Mottled, American Black, and Mexican ducks than they are to Mallards, which occur sympatrically in East Asia. Our data are consistent with the hypothesis that Eastern Spot-billed Ducks and Mallards have hybridized extensively in the Russian Far East. If so, apparent differences in group A and B mtDNA haplotype ratios, effective populations sizes, and migration rates indicate that many more male Eastern Spot-billed Ducks mated with female Mallards and more Eastern Spot-billed Ducks received ODC-6 alleles from Mallards than vice versa. We hypothesize that those differences reflect strong female natal-site fidelity and high levels of male dispersal, and that Mallards significantly outnumber Eastern Spotbilled Ducks in Primorye. Excess heterozygosity in Eastern Spot-billed Ducks (and in Mallards to a lesser extent) is probably maintained by ongoing emigration of Eastern Spot-billed Ducks and Mallards from areas of allopatry outside the Primorye region, where Eastern Spot-billed Ducks and Mallards are predicted to possesses genotypic frequencies historically diagnostic of each species.

[Low genetic differentiation and close evolutionary connection between Anas platyrhynchos and Anas poecilorhyncha: data from RAPD-PCR analysis]

Using RAPD-PCR, we examined genetic diversity and phylogenetic relationships in two groups of river ducks: Anas platyrhynchos, A. poecilorhyncha, A. strepera and A. crecca, A. formosa, A. querquedula. Molecular taxon-specific markers were found for teals (A. crecca, A. formosa, A. querquedula) and gadwall (A. strepera). Each of the species examined was shown to exhibit high genetic diversity. The mean levels of intraspecific genetic polymorphism in the groups of mallards (P = 77%) and teals (P = 74.5%) were approximately equal whereas the mean interspecific genetic distances in teals were significantly higher than in mallards (D = 0.432 and D = 0.336, respectively). The levels of interspecific genetic differentiation in the species groups were also different. The genetic distances between the teal species and between gadwall and mallards were equal to 0.668-0.971 while the genetic distance between mallard A. platyrhynchos and spot-billed duck A. poecilorhyncha was 0.401, which slightly exceeds the intraspecific values for mallards (0.356-0.377). The RAPD patterns for this species pair showed high variability and a lack of fixed differences. This was adequately reflected on both intra- and interspecific differences and on phylogenetic constructions in which the morphological species did not form their own clusters but were intermixed. In contrast to mallards, the other species, which showed high genetic variability, were reliably separated in phenogenetic and phylogenetic reconstructions. The possible explanations of the low genetic differentiation of A. platyrhynchos and A. poecilorhyncha are discussed.

[RAPD-PCR analysis of genetic diversity in the Manchurian pheasant]

The genetic diversity of a local population of the Manchurian pheasant Phasianus colchicus pallasi was studied using RAPD-PCR. Based on the DNA patterns obtained in PCR with five arbitrary decanucleotide primers, we assessed genetic polymorphism of this population, estimated genetic distances between individuals, and constructed an NJ phylogenetic tree, and an UPGMA dendrogram of genetic similarity. The population was shown to exhibit high average genetic polymorphism (P = 79.4%) and genetic distances (D = 0.267). Possible reasons for the high genetic diversity of this local population are discussed.