Adaptive latitudinal variation of the duration and thermal requirements for development in the ground beetle Amara communis (Panz.) (Coleoptera, Carabidae)

The data are obtained on development time at six constant temperatures (12, 14, 16, 18, 20, 22°C) and thermal requirements for preimaginal development in a ground beetle Amara communis from Arkhangelsk (64°34′N) and St. Petersburg (59°53′N). The larval and pupal development times were found to be significantly shorter in the Arkhangelsk than in the St. Petersburg population under all temperatures. As a result, total preimaginal development appeared to be shorter by 6.2–6.6% in the Arkhangelsk population. The regression lines of the larval, pupal and total (egg-to-adult) development rate on temperature for the Arkhangelsk population run above and steeper than the respective lines for the St. Petersburg population. Both populations share the similar values of the thermal thresholds (7.2–8.2°C). This explains faster preimaginal development in the northern population under all temperatures above the threshold. Thus, the slope of the regression lines increases, i.e., the sum of degree-days decreases, whereas the thermal threshold for development exhibited no distinctive changes from south to north in this species. Adults from Arkhangelsk reared in the experiments appeared heavier on the average in comparison with those from St. Petersburg, especially at 18–22°C. Temperature did not significantly affect adult weight, except the fact that the beetles were slightly heavier at 20 and 22°C. Consequently, the well-known “temperature-size rule” is violated in this species. Relative growth rate in larvae of A. communis increased considerably with temperature rise from 14 to 22°C. It was significantly higher in the beetles from Arkhangelsk at 18–22°C. There were no differences in larval growth rate between the two populations at 14 and 16°C.     

Distribution of representatives of the genus <Emphasis Type="Italic">Neoabbottiella</Emphasis> (Rhodophyta: Halymeniales) in the Russian Far Eastern Seas and taxonomic status of <Emphasis Type="Italic">N. valentinae</Emphasis> N. Klochkova et Pisareva, 2013

The new information on distribution of the red algae Neoabbottiella in the Russian Far East changes the concept of the areal of these algae and their preferred temperatures. A comparison of N. valentinae N. Klochkova et Pisareva with Schizymenia dubyi f. palmata Yamada collected by Y. Yamada from Urup Island and stored with its type and paratypes in the collection of Hokkaido University Museum (Sapporo, Japan) showed their conspecificity. Based on the data, N. valentinae was recognized as a synonym of Schizymenia dubyi f. palmata. Since this form does not possess the main generic feature of the genus Schizymenia and at the same time has well-expressed generic features of Neoabbottiella, the form S. dubyi f. palmata is transferred to this genus with the name N. palmata (Yamada) N. Klochkova et Pisareva.     

Sequence specificity of isolated DNA-cytosine methylases from Shigella sonnei 47 cells

Five individual DNA-cytosine methylases differing in pI (isoelectric point) values are present in Shigella sonnei 47-cells. The sequence specificity of each of those was determined 'in vitro' by a highly efficient combined approach that included pyrimidine tract (isostic) analysis, identification of the immediate neighbourhood of the methylated base within the recognition sequence and the calculation method. The enzyme with pI 5.3 (MSso5.3) is the counterpart of the RSso 47 II in the Sso 47 II restriction-modification system and methylates the internal cytosine residue of the 'palindromic' 5'-C-C-N-G-G-3' sequence. The enzymes with pI 6.2 (MSso6.2) and 7.4 (MSso7.4) exhibit identical specificity upon methylation of the 'palindromic' 5'-Py-C-N-G-Pu-3' sequence, but differ in the pI values of the proteins. The enzyme with pI 4.2 (MSso4.2) recognizes the unique tetranucleotide 5'-C-C-C-C-3' sequence and methylates the second cytosine residue at the 5'-end of the sequence. The enzyme with pI 8.4 (MSso8.4) methylates the central cytosine residue within the degenerative trinucleotide 5'-(PuC)-C-C-3' sequence. MSso5.3, MSso6.2, and MSso7.4 are presumed to belong to the 'family' of sequence-specific (Eco RII-like) enzymes. These DNA-cytosine methylases are likely to be evolutionary related to Eco RII and to have undergone a sufficient genetic drift so as to recognize similar (but more degenerative) nucleotide sequences.     

Sequence specificity of isolated DNA-adenine methylases from Mycobacterium smegmatis (butyricum) and Shigella sonnei 47 cells

A set of four individual DNA-adenine methylases differing in pI (isoelectric point) values (MMbu4.2, MMbu6.4, MMbu7.3, and MMbu8.7), and a sole methylating enzyme with the same base specificity (MSso9.5) are present in M. smegmatis (butyricum) and Sh. sonnei 47 cells, respectively. The sequence specificity of each of those was studied 'in vitro' by a combined approach that comprised isostich (purine tract) analysis and identification of the immediate neighbourhood of the methylated base within the sequence methylated. The MSso9.5 recognition site has been established as the hexanucleotide 'palindromic' 5'-G-A-A-T-T-C-3' sequence which is structurally similar to the analogous MEco RI recognition site. However, in contrast to MEco RI, MSso9.5 methylates the 5'-end adenine residue in the sequence and thus it appears to be an isometimer of MEco RI. By means of the same approach, the partial nucleotide sequences methylated by each of the four individual M. butyricum enzymes were determined. MMbu7.3 and MMbu8.7 exhibit the identical sequence specificity upon methylation of the degenerative trinucleotide 5'-Py-A-Py-3' sequence and thus these enzymes are assumed to represent the different molecular forms of the methylase. MMbu4.2 methylates the 5'-G-G-A-3' sequence and thus it is of a great value as the tool for negating effects of the RBam HI and RAva II-type restriction. MMbu6.4 is of a particular interest on account of its unique DNA methylation pattern which is distinguished in the pronounced clustering of purine bases in the 5'-Pu-Pu-Pu-Pu-Pu-3' sequence methylated.     

Increased expression of hepatic DNA methyltransferase in smokers

The DNA methyltransferase enzyme (DNA MTase) catalyzes DNA methylation at cytosines in CpG dinucleotides. 5-Methylcytosine modification of DNA is important in gene regulation, DNA replication, chromatin organization and disease. Increased levels of DNA MTase have been associated with the initiation and promotion of cancer. This study was conducted to assess whether cigarette smoking and other factors, such as age and gender, influence DNA MTase expression in nontumorous tissue. DNA MTase was significantly (p<0.05) higher in samples from cigarette smokers; the mean level of DNA MTase mRNA was almost 2-fold higher in these samples than in those from nonsmokers. Levels of DNA MTase mRNA were higher in samples from females than in those from males, but the difference was not statistically significant. Age was not associated with DNA MTase levels. Increased levels of DNA MTase in individuals who smoke may indicate a greater susceptibility to the risk of cancer since increased levels of this enzyme are found in cancer cell lines and human tumors. The results of this study suggest that further investigations of increased expression of this enzyme as a predisposing factor for cancer susceptibility are needed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Population structure of the Japanese eel, Anguilla japonica

Mitochondrial DNA (mtDNA) sequences that include (a) a part of the cytochrome b gene, (b) two tRNA genes, and (c) a part of the noncoding D-loop region of 31 Anguilla japonica (Japanese eel) and 1 A. marmorata collected from Taiwan, Japan, and mainland China were determined to evaluate the population structure of Japanese eel. Among 30 genotypes identified from the 31 Japanese eel mtDNAs sequenced, there are 58 variable sites, predominantly clustered at the D-loop region. The phylogenetic tree constructed by the unweighted pair-group method with arithmetic mean shows neither significant genealogical branches nor geographic clusters. Furthermore, the sequence-statistics test reveals little, if any, significant genetic differentiation. These results indicate that the 31 Japanese eels might come from a single population. Analysis of sequence variation in mtDNA by using the relationship between the number of segregating sites and the average number of nucleotide differences under the neutral mutation hypothesis reveals that neutral mutation acts as a major factor influencing the evolutionary divergence of the Japanese eel mitochondrial genome sequenced, especially in the noncoding region.      

Molecular evolution of P transposable elements in the genus Drosophila. I. The saltans and willistoni species groups

A phylogenetic survey using the polymerase chain reaction (PCR) has identified four major P element subfamilies in the saltans and willistoni species groups of Drosophila. One subfamily, containing about half of the sequences studied, consists of elements that are very similar to the canonical (and active) P element from D. melanogaster. Within this subfamily, nucleotide sequence differentiation among different copies from the same species and among elements from different species is relatively low. This observation suggests that the canonical elements are relatively recent additions to the genome or, less likely, are evolving slowly relative to the other subfamilies. Elements belonging to the three noncanonical lineages are distinct from the canonical elements and from one another. Furthermore, there is considerably more sequence variation, on the average, within the noncanonical subfamilies compared to the canonical elements. Horizontal transfer and the coexistence of multiple, independently evolving element subfamilies in the same genome may explain the distribution of P elements in the saltans and willistoni species groups. Such explanations are not mutually exclusive, and each may be involved to varying degrees in the maintenance of P elements in natural populations of Drosophila.      

Some peculiarities of phage DDVI-specific methylases]

The types of methylases are found in the cellular extract of Escherichia coli B, infected with phage DDVI. One of them is a cellular enzyme, which methylates adenine to form 6-methylaminopurine (6-MAP) and is repressed in the infected cell in vivo. The second type, which is not found in the non-infected cells, is specific for phage DDVI and induces the formation of 7-methylguanine (7-MG). Both enzymes recognize various sites, which accounts for the ratio 6-MAP/7-MG to vary in heterological DNAs between 2.07 in phage Sd DNA and 0.40 in phage DDII DNA. During in vitro incubation with homologous methylases phage DDVI DNA and especially phage T2 DNA are subjected to further methylation, which is probably indicative of their "undermethylation" in vivo. The DDVI-specific enzyme, similar to B-specific type, methylates DNA with a normal set of nitrogenous bases (phages Sd and DDII), as well as DNAs containing 5-oxymethylcytosine and glucose (phages T2 and DDVI). Both methylases under study use only native double-helical DNA as substrate and are strongly inhibited by S-adenosylhomocysteine. Phage DDVI Methylase is characterized by low stability.