Properties of Polyphosphate Glucokinase in Achromobacter butyri

The activities of polyphosphate glucokinase which synthesizes glucose-6-phosphate from glucose and metaphosphate were found in some microorganisms. This enzyme occurred most abundantly in Micrococcus and Achromobacter species and less in Brevibacterium, Aerobacter and Alcaligenes species. The distribution pattern of this enzyme was closely similar to that of polyphosphate NAD kinase. Polyphosphate glucokinase in A. butyri was different from ATP-dependent glucokinase in some enzymatic properties. The potent phosphoryl donor for this enzyme was metaphosphate, and other chain or ring phosphate polymers were not utilized by this enzyme.     

Finding the Factors of Reduced Genetic Diversity on X Chromosomes of Macaca fascicularis: Male-Driven Evolution,Demography, and Natural Selection

The ratio of genetic diversity on X chromosomes relative to autosomes in organisms with XX/XY sex chromosomes could provide fundamental insight into the process of genome evolution. Here we report this ratio for 24 cynomolgus monkeys (Macaca fascicularis) originating in Indonesia, Malaysia, and the Philippines. The average X/A diversity ratios in these samples was 0.34 and 0.20 in the Indonesian–Malaysian and Philippine populations, respectively, considerably lower than the null expectation of 0.75. A Philippine population supposed to derive from an ancestral population by founding events showed a significantly lower ratio than the parental population, suggesting a demographic effect for the reduction. Taking sex-specific mutation rate bias and demographic effect into account, expected X/A diversity ratios generated by computer simulations roughly agreed with the observed data in the intergenic regions. In contrast, silent sites in genic regions on X chromosomes showed strong reduction in genetic diversity and the observed X/A diversity ratio in the genic regions cannot be explained by mutation rate bias and demography, indicating that natural selection also reduces the level of polymorphism near genes. Whole-genome analysis of a female cynomolgus monkey also supported the notion of stronger reduction of genetic diversity near genes on the X chromosome.     

A soluble form of Siglec-9 provides an antitumor benefit against mammary tumor cells expressing MUC1 in transgenic mice

Tumor-associated MUC1 binds to Siglec-9, which is expected to mediate tumor cell growth and negative immunomodulation. We hypothesized that a soluble form of Siglec-9 (sSiglec-9) competitively inhibits a binding of MUC1 to its receptor molecules like human Siglec-9, leading to provide antitumor benefit against MUC1-expressing tumor, and generated transgenic mouse lines expressing sSiglec-9 (sSiglec-9 Tg). When mammary tumor cells expressing MUC1 were intraperitoneally transplanted into sSiglec-9 Tg, tumor proliferation was slower with the lower histological malignancy as compared with non-transgenic mice. The sSiglec-9 was detected in the ascites caused by the tumor in the sSiglec-9 Tg, and sSiglec-9 and MUC1 were often colocalized on surfaces of the tumor cells. PCNA immunohistochemistry also revealed the reduced proliferation of the tumor cells in sSiglec-9 Tg. In sSiglec-9 Tg with remarkable suppression of tumor proliferation, MUC1 expressions were tend to be reduced. In the ascites of sSiglec-9 Tg bearing the tumor, T cells were uniformly infiltrated, whereas aggregations of degenerative T cells were often observed in the non-transgenic mice. These results suggest that sSiglec-9 has an antitumor benefit against MUC1-expressing tumor in the transgenic mice, which may avoid the negative immunomodulation and/or suppress tumor-associated MUC1 downstream signal transduction, and subsequent tumor proliferation.     

Toward the Quantification of a Conceptual Framework for Movement Ecology Using Circular Statistical Modeling

To analyze an animal’s movement trajectory, a basic model is required that satisfies the following conditions: the model must have an ecological basis and the parameters used in the model must have ecological interpretations, a broad range of movement patterns can be explained by that model, and equations and probability distributions in the model should be mathematically tractable. Random walk models used in previous studies do not necessarily satisfy these requirements, partly because movement trajectories are often more oriented or tortuous than expected from the models. By improving the modeling for turning angles, this study aims to propose a basic movement model. On the basis of the recently developed circular auto-regressive model, we introduced a new movement model and extended its applicability to capture the asymmetric effects of external factors such as wind. The model was applied to GPS trajectories of a seabird (Calonectris leucomelas) to demonstrate its applicability to various movement patterns and to explain how the model parameters are ecologically interpreted under a general conceptual framework for movement ecology. Although it is based on a simple extension of a generalized linear model to circular variables, the proposed model enables us to evaluate the effects of external factors on movement separately from the animal’s internal state. For example, maximum likelihood estimates and model selection suggested that in one homing flight section, the seabird intended to fly toward the island, but misjudged its navigation and was driven off-course by strong winds, while in the subsequent flight section, the seabird reset the focal direction, navigated the flight under strong wind conditions, and succeeded in approaching the island.     

Possible Mechanism of Action of β-Lactam-Enhancing Factor on Methicillin-Resistant Staphylococcus aureus

We have recently found a factor (Factor T) in aged mixtures of tungstate and phosphate which greatly enhances the antibacterial effects of β-lactams on methicillin-resistant strains of staphylococcal species such as methicillin-resistant Staphylococcus aureus (MRSA), but shows only weak effects on methicillin-susceptible S. aureus and bacterial strains other than staphylococci. Factor T alone did not strongly inhibit cell metabolism and bacterial growth unless an excess amount was added. When Factor T was added to the culture medium beforehand, the growth of MRSA cells was rapidly suppressed just after addition of oxacillin (MPIPC). However, the growth of the cells was inhibited gradually when these two reagents were added in reverse order. For full expression of the enhancing effect, it seemed necessary for cells of MRSA strains to be incubated with Factor T for at least 2–3 hr. When the cells were washed after being sensitized by incubating them for 5 hr with Factor T, it took approximately 1 hr for the cells to recover their resistance to MPIPC. Factor T reduced the amount of penicillin-binding protein-2′ (PBP 2′), and thus sensitized the MRSA strains to β-lactams.     

Ornithine Decarboxylase Activity during Sporulation of Bacillus subtilis

A simple method for overproduction of a target protein by genetic engineering techniques has been established. This method involves rearranging the target gene, which contains a ribosome binding sequence for expression, in plurally repeated form, and inserting it in a 3′ lower part of promoters.

The chloramphenicol acetyltransferase (CAT) structural gene was used to demonstrate the validity of this method. E. coli harboring a CAT expression plasmid, pUS(CAT)₁, which had one inserted CAT gene, was able to produce CAT at the level of only 4% of the total cellular protein according to densitometric scanning on Coomassie-blue-stained SDS-polyacrylamide gel and had the CAT activity of 3.9 × 10³ units/mg protein. However, E. coli harboring a CAT expression plasmid, pUS(CAT)₄, which had inserted four directly repeated copies of the CAT gene, could synthesize CAT up to 16% of the total cellular protein and had the CAT activity of 2.8 × 10⁴ units/mg protein. This suggests that this method should be useful for overproducing many important peptides or proteins in bacteria.     

Defect of Mitotic Vimentin Phosphorylation Causes Microophthalmia and Cataract via Aneuploidy and Senescence in Lens Epithelial Cells

Vimentin, a type III intermediate filament (IF) protein, is phosphorylated predominantly in mitosis. The expression of a phosphorylation-compromised vimentin mutant in T24 cultured cells leads to cytokinetic failure, resulting in binucleation (multinucleation). The physiological significance of intermediate filament phosphorylation during mitosis for organogenesis and tissue homeostasis was uncertain. Here, we generated knock-in mice expressing vimentin that have had the serine sites phosphorylated during mitosis substituted by alanine residues. Homozygotic mice (VIM^SA/SA) presented with microophthalmia and cataracts in the lens, whereas heterozygotic mice (VIM^WT/SA) were indistinguishable from WT (VIM^WT/WT) mice. In VIM^SA/SA mice, lens epithelial cell number was not only reduced but the cells also exhibited chromosomal instability, including binucleation and aneuploidy. Electron microscopy revealed fiber membranes that were disorganized in the lenses of VIM^SA/SA, reminiscent of similar characteristic changes seen in age-related cataracts. Because the mRNA level of the senescence (aging)-related gene was significantly elevated in samples from VIM^SA/SA, the lens phenotype suggests a possible causal relationship between chromosomal instability and premature aging.