Regulatory DNA sequence conserved in the course of BK virus evolution

Summary Within the genome of human polyomavirus BK (BKV), there exists a noncoding regulatory region toward the late region side of the origin of DNA replication. In most BKV strains isolated by viral culture, this regulatory region contains tandem repeats varying in size. Recently. however, several laboratories isolated new BKV strains (designated as archetypal strains) lacking such repeat sequences. To examine the genetic relationship between archetypal strains, a phylogenetic tree was constructed for seven BKV strains, including three archetypal strains, from DNA sequence data on the late genes, those for leader protein (agnoprotein), and those for structural proteins (VP1, VP2, and VP3). For three strains data previously reported were used, whereas for the others sequences were determined in this study. From total numbers of nucleotide substitutions in each pair of strains, a phylogenetic tree was constructed by the unweighted pair-group method. The phylogenetic tree obtained reveals that BKV strains containing the archetypal regulatory region do not constitute a cluster of closely related strains and that these strains, together with those carrying the major part of the archetypal regulatory region, are widespread in the BKV population. This finding suggests that the basic structure of the archetypal regulatory region has been conserved in the course of BKV evolution.     

Unveiling the origin of Quercus serrata subsp. mongolicoides found in Honshu,Japan, by using genetic and morphological analyses

Quercus mongolica is a tree found in temperate deciduous forests in east Asia. In Japan, Q. mongolica var. crispula is commonly found; moreover, an oak whose morphology is similar to that of Q. mongolica var. mongolica of the Asian continent has been found in certain areas of Honshu and Hokkaido. Recently, the oak found in Honshu was described as Q. serrata subsp. mongolicoides (QSM). However, genetic comparison between this oak and Q. mongolica var. mongolica of the Asian continent has not been performed; the origin of QSM is thus unknown. Therefore, we aimed to determine the origin of QSM by conducting nuclear microsatellite (nSSR), chloroplast DNA (cpDNA) and leaf morphology analyses for the three taxa, as well as other congeners. The cpDNA variation overlapped among the three taxa, suggesting low discrimination ability for these taxa. Although morphological congruency was found between QSM and Q. mongolica var. mongolica, results of nSSR analyses showed that QSM contained a genetic admixture of Q. mongolica var. mongolica of the Asian continent and Q. mongolica var. crispula of Japan, bolstering an admixture hypothesis. The nSSR and cpDNA analyses suggested that Q. mongolica var. crispula can be the progenitor of Q. mongolica var. mongolica and harbors the ancestral cpDNA haplotypes. Therefore, we concluded that QSM might have been created by an admixture that likely occurred within Japan between Q. mongolica var. crispula and putative relict Q. mongolica var. mongolica, which might have diverged in or around Japan from Q. mongolica var. crispula during the late Pleistocene.     

Transdifferentiation of putative neuronal cells of neural retina into lens: A demonstration by chick-quail chimeric cultures

Summary To elucidate the cell-type origin of lens cells, which differentiate in stationary cultures of neural retina, chimeric cultures between chick and quail cells were made to recombine xenoplastically the different cell fractions separated from 8- to 9-day cultures of 3.5-day-old embryonic neural retinal cells by means of centrifugation in Percoll. Extensive lentoidogenesis occurred in the recombination of the N2-fraction (consisting mostly of small round cells) with the E-fraction (containing a number of flattened epithelial cells). Taking advantage of the difference in electrophoretic mobility of chick and quail -crystallin, it was shown that this lens-specific protein, synthesized in the chimeric cultures, was mostly of the species-specificity of N2. Microscopic observations of histological sections of cell sheets of quail N2- and chick E-fraction chimeric cultures revealed that most cells with -crystallin, as identified by means of immunohistological detection, are provided with a nuclear marker characteristic of quail. By determining the level of activity of choline acetyltransferase and by examining the stainability with a fluorescent dye (Merocyanine-540), it was suggested that cells in the N2-fraction are primitive neuroblast-like cells. Thus, we can conclude that putative neuronal cells in early cultures of avian embryonic neural retina can transdifferentiate into lens cells.     

Gametes and fertilization in the Chinese hamster

Freshly ovulated eggs are each surrounded by a compact cumulus oophorus. The overall diameter of the normal egg (including the zona pellucida) is about 100 μm. Cumulus cells, particularly those near the egg, are arranged redially in a viscous noncellular matrix. The spermatozoon is about 250 μm in length. The head a large acrosome, changes in which can be readily examined with the light (phase- contrast) microsope. When exposed to physiological salt solutions, testicular spermatozoa either were motionless or flexed the posterior half of their tails slowly. Spermatozoa from the caput epididymis were highly motile, flexing the entire tail. A few of them moved progressively. Mature spermatozoa from the vas deferens were highly motile and moved either straightforward or in a circle. They vibrated their tails stiffly without flexing them. In normally mated females, fertilization began sometime between 2 and 3 h after ovulation and was completed within the next 4 to 5 h. Spermatozoa swimming in the ampullary fluid or within the cumulus oophorus about the time of fertilization flexed the anterior half (which roughly corresponds to the midpieac region) of their tails. This peculiar movement may be homologous to the so-called “hyperactivation” of spermatozoa as reported in several other mammalian species. Actively motile spermatozoa within the cumulus or no the zona pellucida had either modified (“collapsed”) or no acrosomal caps. The sperm head usually passed verticually or nearly through the zona, but the path was oblique in some instances. In 54% of the recently fertilized eggs examined, the entire length of the sperm tail was within the perivitelline space; in the other 46% of the eggs varying lenghts of the tail remined the perivitelline space, the tails were extruded from the vitellus of many eggs even before the eggs began their first cleavage. When unfertilized eggs in the cumulus oophorus were inseminated with vas deferens spermatozoa in a modified Tyrode's solution (m-TALP), about 80% of them were ferrtilized by 4–6 h after insemination. The vast majority were monospermic. When eggs were freed from the cumulus prior to insemination, none were fertilized, suggesting that the cumulus cells or their matrix assisted capacitation and/or the acrosome reaction of the spermatozoa under the in vitro conditions employed. No eggs were fertilized by the testicular or caput epididymal spermatozoa regardless of the presence or absence of cumulus oophorus around the eggs at the time of insemination.     

Identification of a binding region on Escherichia coli heat-stable enterotoxin to intestinal guanylyl cyclase C

Summary The heat-stable enterotoxin (ST), produced byEscherichia coli, causes acute diarrhea in infants and domestic animals by activation of the intestinal membrane-bound receptor, guanylyl cyclase C. We have investigated a region on the ST molecule, which is recognized by the receptor, by introducing a photochromophore,p-azidophenylalanine (Pap), into three different regions of STp(4–17), which has the full toxic activity. Each ST analog bound to the receptor, but only STp(4–17) containing a Pap residue at position 11 in the central portion of the ST molecule, showed a high efficiency in the reaction which cross-linked with the receptor by UV radiation. These data clearly demonstrate that the region of the ST molecule encompassing the Asn¹¹ residue directly interacts with the receptor.     

Anatomic and chromosomal anomalies in 944 induced abortuses

Summary A total of 944 induced abortuses, 922 of which apparently were anatomically normal and 22 of which were anatomically abnormal, were set up in culture. Of these abortuses, 910 (96.4%) were successfully karyotyped. The study can be divided into two periods. In the initial period, specimens without recovered fetal tissues were excluded, and no chromosome anomalies were found among the 182 abortuses karyotyped. In the later period of sutdy, abortion specimens both with and without recovered fetal tissues were included, and 23 chromosomally abnormal abortuses, 9 of which were without recovered fetal tissues, were found among the 728 abortuses karyotyped. This gives a chromosome abnormality rate of 3.2%. The mean ovulation age for the 728 abortuses was 63.4 days (range 33–109 days). The mean maternal age was 28.4 years (range 15–48 years). The chromosomally abnormal abortuses included 13 (10 nonmosaic and 3 mosaic) trisomics, 7 triploids, 2 abortuses with balanced D/D translocations and an abortus with an XXq- karyotype. Among the 616 abortuses in which both amniotic and fetal tissues were karyotyped, there was complete karyotypic agreement between the two tissues. Among the 339 abortuses in which tissue samples from both sides of the body were analyzed, complete agreement was also found. Factors that may influence the prevalence of abnormal karyotypes in induced abortuses are discussed.     

Antagonism Between Osmophilic Lactic Acid Bacteria and Yeasts in Brine Fermentation of Soy Sauce

Brine fermentation by osmophilic lactic acid bacteria and yeasts for long periods of time is essential to produce a good quality of shoyu (Japanese fermented soy sauce). It is well known that lactic acid fermentation by osmophilic lactic acid bacteria results in the depression of alcoholic fermentation by osmophilic yeasts, but the nature of the interaction between osmophilic lactic acid bacteria and yeasts in brine fermentation of shoyu has not been revealed. The inhibitory effect of osmophilic lactic acid bacteria on the growth of osmophilic yeasts was investigated. It was recognized that osmophilic shoyu yeasts such as Saccharomyces rouxii and Torulopsis versatilis were inhibited by a metabolite produced by osmophilic lactic acid bacteria (belonging to Pediococcus halophilus) in brine fermentation of shoyu. The primary inhibitor was considered to be acetic acid, although lactic acid was slightly inhibitory.     

Evaluation of global warming impacts on the carbon budget of terrestrial ecosystems in monsoon Asia: a multi-model analysis

This study assesses the potential impacts of future global warming on the carbon budget of terrestrial ecosystems across monsoon Asia using the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) dataset. We used simulation results of two emission pathways (RCP2.6 and RCP8.5), climate projections of five climate models, and seven terrestrial biome models to analyze the changes in net primary production and carbon stocks in the South, Southeast, and East Asian subregions during the period 1981–2099. The simulations indicated that by the end of the 21st century, net primary production would increase by 9–45 % and ecosystem carbon storage would increase by 42–86 Pg C. The clearest climatic impacts were found when using the adaptation-oriented emission scenario (RCP8.5), which assumes a greater CO₂ increase and a larger change in climatic conditions. Substantial disparities in temporal trajectories and spatial patterns were found in the estimated changes, owing to the uncertainties in the emission scenarios, climate projections, and ecosystem models. We attempted to derive consistent patterns throughout the simulations to specify potential hotspots of climatic impacts (e.g., soil carbon change in the southern Tibetan Plateau). Finally, we discuss changes to the climatic characteristics in the study region (e.g., a change in the rainy season), the implications for ecosystem services, and the need for collaborative field monitoring studies.     

Nucleotide substitutions in Staphylococcus aureus strains, Mu50, Mu3, and N315.

A specific phenotype of Staphylococcus aureus strains Mu50 and Mu3 is characterized by thickened cell wall and moderate resistance to vancomycin. The N315 strain is a prototype of methicillin-resistant S. aureus (MRSA), but it is methicillin susceptible, despite carrying the mecA resistance gene. Here, we revised differences in the sequences of Mu50 and N315, referencing that of Mu3 which were assumed to be of one lineage. The 362 ORFs diverse between Mu50 and N315 were picked up, and the corresponding ones in three strains were re-sequenced. This defined 213 ORFs diverse between Mu50 and N315, and 9 between Mu50 and Mu3. The fixed diversities of 174 ORFs (except for 39 silent ORFs from 213), including nucleotide substitution (NSs), frame shift, and truncation were grouped into three major functional categories, which were transport (14.9% in the 174 diverse ORFs), metabolism of carbohydrates (5.7%), and RNA synthesis (9.6%). The other gene categories had small diversities. These gene categories seemed to be functionally decisive for the Mu50-specific characters, the thickened cell wall and moderate vancomycin resistance. All of the diverse genes and the high quality sequence of Mu50 can be viewed at the web site (http://133.5.48.239/VRSA/).