Concerning the dynamic instability of actin homolog ParM

Apoptosis is a highly conserved procedure of cell death and occurs under various stimuli, including oxidative stress. A small heat shock protein, alphaB-crystallin, is found to process resistance to apoptosis in some cells and tissues. But the mechanisms under this protective role are not fully understood. In the present study, we reported the early protective role of alphaB-crystallin against hydrogen peroxide-induced apoptosis in mice myogenic C(2)C(12) cells. alphaB-Crystallin interacted with p53, a proapoptotic protein, during cell apoptosis and such protein interaction mainly occurred in the cytoplasm of the cells, suggesting that the interaction of alphaB-crystallin with p53 might prevent the translocation of p53 from cytoplasm to mitochondria. Hence, this study provides a hint that alphaB-crystallin affects on p53 mitochondrial translocation during oxidative stress-induced apoptosis.     

IRS-1 transgenic mice show increased epididymal fat mass and insulin resistance

Insulin receptor substrate-1 (IRS-1) is the major substrate of both the insulin receptor and the IGF-1 receptor. In this study, we created IRS-1 transgenic (IRS-1-Tg) mice which express human IRS-1 cDNA under control of the mouse IRS-1 gene promoter. In the IRS-1-Tg mice, IRS-1 mRNA expression was significantly increased in almost all tissues, but its protein expression was increased in very limited tissues (epididymal fat and skeletal muscle). IRS-1-Tg mice showed glucose intolerance and significantly enlarged epididymal fat mass, as well as elevated serum TNF-α concentrations. Importantly insulin signaling was significantly attenuated in the liver of IRS-1-Tg mice, which may contribute to the glucose intolerance. Our results suggest that excess IRS-1 expression may not provide a beneficial impact on glucose homeostasis in vivo.     

Tidal and diurnal variations in larval fish abundance in an estuarine inlet in Ariake Bay,Japan: implication for selective tidal stream transport

We have conducted a preliminary study of tidal and diurnal variations in the distribution of dominant larval and juvenile fishes in the Chikugo River inlet (Ariake Bay, Kyushu, Japan) to determine whether selective tidal stream transport (STST) occurs. Larval and juvenile fish were collected from the mesohaline zone of the Chikugo River inlet during spring 2002. Temperature, salinity, depth, and current velocity were measured. Larval and juvenile abundance were compared among four tidal conditions, flooding tide, high tide, ebbing tide, and low tide, and between day and night. A total of 12 families, 15 species, and 5,577 individuals were collected. Temperature did not vary significantly with tidal conditions whereas salinity, depth, and current velocity varied significantly. Salinity also was correlated significantly and positively with depth. The abundance of most of the fishes was correlated positively and significantly with salinity and depth. Lateolabrax japonicus, Trachidermus fasciatus, Acanthogobius hasta, and other gobiid larvae (Gobiidae spp.) were significantly more abundant during high tide; in contrast, Coilia nasus and Neosalanx reganius were most abundant during low tide. The abundance of most of the fishes was higher during high tides at night than during the day, indicating the existence of STST, which may be strategically associated with ascending progress to upstream nursery areas.     

The intramembrane active site of GlpG, an E. coli rhomboid protease, is accessible to water and hydrolyses an extramembrane peptide bond of substrates

Escherichia coli GlpG is an orthologue of the rhomboid proteases that catalyse intramembrane proteolysis of specific membrane proteins. We previously showed that it can cleave a type I model membrane protein, Bla-LY2-MBP, having the second transmembrane region of lactose permease (LY2) in vivo and in vitro at the predicted periplasm-membrane boundary region of LY2. Here we investigated the environment of the active site regions of GlpG in the membrane-integrated state by examining the modifiability of Cys residues introduced into the regions around the catalytic residues with membrane-permeable and -impermeable alkylating reagents. The results indicate that the enzyme active site is fully open to the external aqueous phase. GlpG also cleaved a similar fusion protein, Bla-GknTM-MBP, having the transmembrane region of Gurken (GknTM), a physiological substrate of Drosophila rhomboids. Engineered Cys residues in the cleavage site regions of the LY2 and GknTM sequences were efficiently modified with a membrane-impermeable alkylating reagent, showing that these regions are exposed to the periplasm. These results suggest that GlpG cleaves an extramembrane region of substrates, unlike the currently prevailing view that this class of membrane proteases acts against a membrane-embedded polypeptide segment after its lateral entrance into the enzyme's active site.     

Boss/Sev signaling from germline to soma restricts germline-stem-cell-niche formation in the anterior region of Drosophila male gonads

Drosophila germline stem cells are regulated by the somatic microenvironment, or "niche," which ensures that the stem cells can both self-renew and produce functional gametes throughout adult life. However, despite its prime importance, little is known about how niche formation is regulated during gonadal development. Here, we demonstrate that a receptor tyrosine kinase, Sevenless (Sev), is required to ensure that the niche develops in the anterior region of the male embryonic gonads. Sev is expressed in somatic cells within the posterior region of the gonads. Sev is activated by a ligand, Bride of sevenless (Boss), which is expressed by the germline, to prevent ectopic niche differentiation in the posterior gonadal somatic cells. Thus, we propose that signal transduction from germline to soma restricts expansion of the germline-stem-cell niche in the gonads.     

Immunogenicity and safety of an inactivated quadrivalent influenza vaccine in healthy adults: a phase II,open‐label,uncontrolled trial in Japan

Two antigenically distinct B strain lineages of influenza virus have co‐circulated since the mid‐1980s; however, inactivated trivalent influenza vaccines contain only one B lineage. The mismatch between the circulating and vaccine lineages has been a worldwide issue. In this study, an inactivated quadrivalent influenza vaccine (QIV) candidate containing two B lineages was manufactured and its immunogenicity and safety evaluated in an open‐label, uncontrolled trial. In this phase II trial, 50 subjects aged 20–64 years received two doses of QIV s.c. 1 to 4 weeks apart. Sera were collected pre‐ and post‐vaccination and safety assessed from the first vaccination to 21 ± 7 days after the second vaccination. After the first vaccination, hemagglutination inhibition titers against each strain increased markedly; the seroconversion rate, geometric mean titer ratio and seroprotection rate being 94.0%, 24.93, and 100.0%, respectively, for the A/H1N1pdm09 strain; 94.0%, 12.47, and 98.0%, respectively, for the A/H3N2 strain; 54.0%, 4.99, and 66.0%, respectively, for B/Yamagata strain, and 72.0%, 6.23 and 80.0%, respectively, for the B/Victoria strain, thus fulfilling the criteria of the European Medical Agency's Committee for Medicinal Products for Human Use. Also, the QIV induced sufficient single radial hemolysis and neutralizing antibodies against all four vaccine strains. No noteworthy adverse events were noted. The results of this trial demonstrate that QIV is well tolerated and immunogenic for each strain, suggesting that QIV potentially improves protection against influenza B by resolving the issue of B lineage mismatch.     

The FHA domain determines Drosophila Chk2/Mnk localization to key mitotic structures and is essential for early embryonic DNA damage responses

DNA damage responses, including mitotic centrosome inactivation, cell-cycle delay in mitosis, and nuclear dropping from embryo cortex, maintain genome integrity in syncytial Drosophila embryos. A conserved signaling kinase, Chk2, known as Mnk/Loki, is essential for the responses. Here we demonstrate that functional EGFP-Mnk expressed from a transgene localizes to the nucleus, centrosomes, interkinetochore/centromere region, midbody, and pseudocleavage furrows without DNA damage and in addition forms numerous foci/aggregates on mitotic chromosomes upon DNA damage. We expressed EGFP-tagged Mnk deletion or point mutation variants and investigated domain functions of Mnk in vivo. A triple mutation in the phosphopeptide-binding site of the forkhead-associated (FHA) domain disrupted normal Mnk localization except to the nucleus. The mutation also disrupted Mnk foci formation on chromosomes upon DNA damage. FHA mutations and deletion of the SQ/TQ-cluster domain (SCD) abolished Mnk transphosphorylations and autophosphorylations, indicative of kinase activation after DNA damage. A potent NLS was found at the C-terminus, which is required for normal Mnk function. We propose that the FHA domain in Mnk plays essential dual functions in mediating embryonic DNA damage responses by means of its phosphopeptide-binding ability: activating Mnk in the nucleus upon DNA damage and recruiting Mnk to multiple subcellular structures independently of DNA damage.     

Construction of a virtual Mycobacterium tuberculosis consensus genome and its application to data from a next generation sequencer

Background

Although Mycobacterium tuberculosis isolates are consisted of several different lineages and the epidemiology analyses are usually assessed relative to a particular reference genome, M. tuberculosis H37Rv, which might introduce some biased results. Those analyses are essentially based genome sequence information of M. tuberculosis and could be performed in sillico in theory, with whole genome sequence (WGS) data available in the databases and obtained by next generation sequencers (NGSs). As an approach to establish higher resolution methods for such analyses, whole genome sequences of the M. tuberculosis complexes (MTBCs) strains available on databases were aligned to construct virtual reference genome sequences called the consensus sequence (CS), and evaluated its feasibility in in sillico epidemiological analyses.

Results

The consensus sequence (CS) was successfully constructed and utilized to perform phylogenetic analysis, evaluation of read mapping efficacy, which is crucial for detecting single nucleotide polymorphisms (SNPs), and various MTBC typing methods virtually including spoligotyping, VNTR, Long sequence polymorphism and Beijing typing. SNPs detected based on CS, in comparison with H37Rv, were utilized in concatemer-based phylogenetic analysis to determine their reliability relative to a phylogenetic tree based on whole genome alignment as the gold standard. Statistical comparison of phylogenic trees based on CS with that of H37Rv indicated the former showed always better results that that of later. SNP detection and concatenation with CS was advantageous because the frequency of crucial SNPs distinguishing among strain lineages was higher than those of H37Rv. The number of SNPs detected was lower with the consensus than with the H37Rv sequence, resulting in a significant reduction in computational time. Performance of each virtual typing was satisfactory and accorded with those published when those are available.

Conclusions

These results indicated that virtual CS constructed from genome sequence data is an ideal approach as a reference for MTBC studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1368-9) contains supplementary material, which is available to authorized users.     

Wide distribution of O157-antigen biosynthesis gene clusters in Escherichia coli

Most Escherichia coli O157-serogroup strains are classified as enterohemorrhagic E. coli (EHEC), which is known as an important food-borne pathogen for humans. They usually produce Shiga toxin (Stx) 1 and/or Stx2, and express H7-flagella antigen (or nonmotile). However, O157 strains that do not produce Stxs and express H antigens different from H7 are sometimes isolated from clinical and other sources. Multilocus sequence analysis revealed that these 21 O157:non-H7 strains tested in this study belong to multiple evolutionary lineages different from that of EHEC O157:H7 strains, suggesting a wide distribution of the gene set encoding the O157-antigen biosynthesis in multiple lineages. To gain insight into the gene organization and the sequence similarity of the O157-antigen biosynthesis gene clusters, we conducted genomic comparisons of the chromosomal regions (about 59 kb in each strain) covering the O-antigen gene cluster and its flanking regions between six O157:H7/non-H7 strains. Gene organization of the O157-antigen gene cluster was identical among O157:H7/non-H7 strains, but was divided into two distinct types at the nucleotide sequence level. Interestingly, distribution of the two types did not clearly follow the evolutionary lineages of the strains, suggesting that horizontal gene transfer of both types of O157-antigen gene clusters has occurred independently among E. coli strains. Additionally, detailed sequence comparison revealed that some positions of the repetitive extragenic palindromic (REP) sequences in the regions flanking the O-antigen gene clusters were coincident with possible recombination points. From these results, we conclude that the horizontal transfer of the O157-antigen gene clusters induced the emergence of multiple O157 lineages within E. coli and speculate that REP sequences may involve one of the driving forces for exchange and evolution of O-antigen loci.