Expression of the primary carbohydrate component of the Bordetella bronchiseptica biofilm matrix is dependent on growth phase but independent of Bvg regulation

We previously showed that the Bvg virulence control system regulates biofilm formation in Bordetella bronchiseptica (Y. Irie, S. Mattoo, and M. H. Yuk, J. Bacteriol. 186:5692-5698, 2004). Analyses of the extracellular components of B. bronchiseptica biofilm matrix revealed that the major sugar component in the matrix was xylose, and linkage analysis indicated a majority of it to be in a 4-linked polymeric form. The production of xylose was independent of Bvg regulation but instead was dependent on bacterial growth phase. In addition, N-acetyl-glucosamine in the matrix was found to be important for the initial development of the biofilm. These results suggest that B. bronchiseptica biofilm formation is growth phase dependent in addition to being regulated by the Bvg virulence system.     

Two isoforms of chicken melanopsins show blue light sensitivity

Melanopsin is a vertebrate non-visual opsin and functions as a circadian photoreceptor in mammalian retinas. Here we found the expression of two kinds of melanopsin genes in the chicken pineal gland and identified the presence of five isoforms derived from these two genes. Reconstitution of the recombinant proteins with 11-cis-retinal revealed that at least two of these melanopsin protein isoforms can function as blue-sensitive photopigments with absorption maxima at 476-484nm. These values are consistent with maximal sensitivities of action spectra determined from the physiological and behavioral studies on mammalian melanopsins. The melanopsin isoforms found in this study may function as pineal circadian photoreceptors.     

Isolation and characterization of the gene encoding a chitin synthase with a myosin motor-like domain from the edible basidiomycetous mushroom, <Emphasis Type="Italic">Lentinula edodes</Emphasis>, and its expression in the course of fruit-body formation

We isolated and characterized the genomic and complementary DNAs encoding a chitin synthase from an edible basidiomycetous mushroom, Lentinula edodes. The gene (which we designated Lechs1) contains a large open reading frame encoding a polypeptide of 1937 amino acid residues. The open reading frame is interrupted by 14 small introns (49–116 bp). The gene product (LeChs1) consists of a myosin motor-like domain in its N-terminal half and a chitin synthase domain in its C-terminal half, analogous to the class V and VI chitin synthases of other filamentous fungi. Phylogenetic analysis demonstrated that LeChs1 is classified into class VI chitin synthases. Southern blot analysis indicated that Lechs1 is a single-copy gene per haploid genome and that L. edodes has no other highly homologous chitin synthase genes. Northern blot analysis revealed that Lechs1 is expressed throughout the whole stages of fruit-body formation of L. edodes, but its expression level gradually declines in a fruit body-maturation-dependent manner with highest expression in vegetative mycelia and fruit body at the early stage of maturation (immature fruit body). This is the first report on the isolation and characterization of the gene encoding a chitin synthase with a myosin motor-like domain from basidiomycetes.     

Purification, characterization, and molecular cloning of organic-solvent-tolerant cholesterol esterase from cyclohexane-tolerant Burkholderia cepacia strain ST-200

Extracellular cholesterol esterase of Burkholderia cepacia strain ST-200 was purified from the culture supernatant. Its molecular mass was 37 kDa. The enzyme was stable at pH 5.5–12 and active at pH 5.5–6, showing optimal activity at pH 7.0 at 45°C. Relative to the commercially available cholesterol esterases, the purified enzyme was highly stable in the presence of various water-miscible organic solvents. The enzyme preferentially hydrolyzed long-chain fatty acid esters of cholesterol, except for that of cholesteryl palmitate. The enzyme exhibited lipolytic activity toward various p-nitrophenyl esters. The hydrolysis rate of p-nitrophenyl caprylate was enhanced 3.5- to 7.2-fold in the presence of 5–20% (vol/vol) water-miscible organic solvents relative to that in the absence of organic solvents. The structural gene encoding the cholesterol esterase was cloned and sequenced. The primary translation product was predicted to be 365 amino acid residues. The mature product is composed of 325 amino acid residues. The amino acid sequence of the product showed the highest similarity to the lipase LipA (87%) from B. cepacia DSM3959.     

Anhydrobiosis-associated nuclear DNA damage and repair in the sleeping chironomid: linkage with radioresistance

Anhydrobiotic chironomid larvae can withstand prolonged complete desiccation as well as other external stresses including ionizing radiation. To understand the cross-tolerance mechanism, we have analyzed the structural changes in the nuclear DNA using transmission electron microscopy and DNA comet assays in relation to anhydrobiosis and radiation. We found that dehydration causes alterations in chromatin structure and a severe fragmentation of nuclear DNA in the cells of the larvae despite successful anhydrobiosis. Furthermore, while the larvae had restored physiological activity within an hour following rehydration, nuclear DNA restoration typically took 72 to 96 h. The DNA fragmentation level and the recovery of DNA integrity in the rehydrated larvae after anhydrobiosis were similar to those of hydrated larvae irradiated with 70 Gy of high-linear energy transfer (LET) ions ((4)He). In contrast, low-LET radiation (gamma-rays) of the same dose caused less initial damage to the larvae, and DNA was completely repaired within within 24 h. The expression of genes encoding the DNA repair enzymes occurred upon entering anhydrobiosis and exposure to high- and low-LET radiations, indicative of DNA damage that includes double-strand breaks and their subsequent repair. The expression of antioxidant enzymes-coding genes was also elevated in the anhydrobiotic and the gamma-ray-irradiated larvae that probably functions to reduce the negative effect of reactive oxygen species upon exposure to these stresses. Indeed the mature antioxidant proteins accumulated in the dry larvae and the total activity of antioxidants increased by a 3-4 fold in association with anhydrobiosis. We conclude that one of the factors explaining the relationship between radioresistance and the ability to undergo anhydrobiosis in the sleeping chironomid could be an adaptation to desiccation-inflicted nuclear DNA damage. There were also similarities in the molecular response of the larvae to damage caused by desiccation and ionizing radiation.     

A Burkitt-lymphoma variant translocation (2p-; 8q+) in a patient with ALL,L3 (Burkitt type)

Summary A patient with acute lymphoblastic leukemia (ALL) whose cells had L3 (Burkitt-type) morphology was found to have a variant translocation t(2;8)(p13;q24), that has been reported only in Burkitt lymphomas. This observation provides additional evidence for a close association of particular karyotypic abnormalities with both Burkitt-type ALL and Burkitt lymphoma.     

Functional expression of thiocyanate hydrolase is promoted by its activator protein, P15K

Thiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, gammaCys131-SO(2)H. When the SCNase alpha, beta and gamma subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (alphabetagamma)(4), like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase((+P15K))) possessed 0.86 Co atom/alphabetagamma trimer and exhibited 78% of the activity of native SCNase. SCNase((+P15K)) showed a UV-Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase((+P15K)) had the gammaCys131-SO(2)H modification. These results indicate that SCNase((+P15K)) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion.     

Copulatory behavior unaccompanied by ovulation in the Japanese monkey (Macaca fuscata)

Copulatory behavior unrelated to conception is sometimes observed in some non-human primates including the Japanese monkey. In the present study, the authors examined whether a mature follicle or a newly formed fresh corpus luteum was observed in the ovaries of female Japanese monkeys which displayed the copulatory behavior unrelated to conception. Post-conception copulatory behaviors were observed in three out of four females usually kept in individual cages in an air-conditioned room, and in two out of three females without infants kept in an outdoor group cage. However, neither a mature Graafian follicle nor a fresh corpus luteum formed newly after conception was observed in any of these females by laparoscopic examinations conducted immediately after termination of the copulatory behavior. In females with infants born in the preceding birth season, copulatory behaviors were observed in three out of four females kept in the outdoor group cage, and in two out of four females in a free-ranging troop. Ovulation was confirmed in one case out of the three kept in the outdoor group cage, but neither a mature follicle nor a newly formed corpus luteum was observed in the remaining four females. These findings suggest that copulatory behavior in the Japanese monkey is not always controlled by the development of a follicle or ovulation in the ovary.