The Role of Notch Signaling in Adult Neurogenesis

Neurogenesis occurs throughout adulthood in the mammalian brain. Newly born neurons are incorporated into the functional networks of both the olfactory bulb and the hippocampal dentate gyrus, and there is growing evidence that adult neurogenesis is important for various brain functions. Continuous neurogenesis is achieved by the coordinated proliferation and differentiation of adult neural stem cells. In this review, we discuss the recent findings concerning the roles of Notch signaling in adult neural stem cells.     

Anticancer effects of 6-<Emphasis Type="Italic">o</Emphasis>-palmitoyl-ascorbate combined with a capacitive-resistive electric transfer hyperthermic apparatus as compared with ascorbate in relation to ascorbyl radical generation

The aim of the present study is to determine the anti-proliferative activity of 6-o-palmitoyl-l-ascorbic acid (Asc6Palm) that is a lipophilic derivative of l-ascorbic acid (Asc), on human tongue squamous carcinoma HSC-4 cells by combined use of hyperthermia in comparison to Asc. Asc6Palm or Asc were administered to HSC-4 cells for 1 h, to which hyperthermia at 42 °C was applied for initial 15 min. After further 1–72 h incubation at 37 °C, cell proliferation was determined with Crystal Violet staining. Ascorbyl radical (AscR) in HSC-4 cell suspension was measured by electron spin resonance (ESR), and cell morphology was observed with scanning electron microscopy (SEM). At 37 °C, 4 mM Asc or 0.35 mM Asc6Palm were enough to suppress proliferation of HSC-4 cells. By combined use of hyperthermia at 42 °C, cell proliferation was decreased when compared to 37 °C. After Asc of 4 mM was incubated with HSC-4 cell suspensions at 37 °C or 42 °C for 0–180 min, the signal intensity of ascorbyl radical (AscR) by ESR was not different regardless of the presence or absence of cells at 37 °C, whereas AscR signal was enlarged in the presence of HSC-4 cells at 42 °C. It was suggested that oxidation of Asc occurred rapidly in HSC-4 cells by hyperthermia, and thereby enhanced the anti-proliferative activity. By SEM observation, the surface of HSC-4 cells treated with Asc6Palm revealed distinct morphological changes. Thus, the combined regimen of Asc6Palm and hyperthermia is expected to exert a marked antitumor activity.     

Male Killing and Incomplete Inheritance of a Novel <Emphasis Type="Italic">Spiroplasma</Emphasis> in the Moth <Emphasis Type="Italic">Ostrinia zaguliaevi</Emphasis>

Bacteria of the genus Spiroplasma are widely found in plants and arthropods. Some of the maternally transmitted Spiroplasma endosymbionts in arthropods are known to kill young male hosts (male killing). Here, we describe a new case of Spiroplasma-induced male killing in a moth, Ostrinia zaguliaevi. The all-female trait caused by Spiroplasma was maternally inherited for more than 11 generations but was spontaneously lost in several lineages. Antibiotic treatment eliminated the Spiroplasma infection and restored the 1:1 sex ratio. The survival rates and presence/absence of the W chromosome in the embryonic and larval stages of O. zaguliaevi showed that males were selectively killed, exclusively during late embryogenesis in all-female broods. Based on phylogenetic analyses of 16S rRNA, dnaA and rpoB gene sequences, the causative bacteria were identified as Spiroplasma belonging to the tick symbiont Spiroplasma ixodetis clade. Electron microscopy confirmed bacterial structures in the follicle cells and follicular sheath of adult females. Although many congeneric Ostrinia moths harbor another sex ratio-distorting bacterium (Wolbachia), only O. zaguliaevi harbors Spiroplasma.     

Combined effect of improved cell yield and increased specific productivity enhances recombinant enzyme production in genome-reduced Bacillus subtilis strain MGB874

Genome reduction strategies to create genetically improved cellular biosynthesis machineries for proteins and other products have been pursued by use of a wide range of bacteria. We reported previously that the novel Bacillus subtilis strain MGB874, which was derived from strain 168 and has a total genomic deletion of 874 kb (20.7%), exhibits enhanced production of recombinant enzymes. However, it was not clear how the genomic reduction resulted in elevated enzyme production. Here we report that deletion of the rocDEF-rocR region, which is involved in arginine degradation, contributes to enhanced enzyme production in strain MGB874. Deletion of the rocDEF-rocR region caused drastic changes in glutamate metabolism, leading to improved cell yields with maintenance of enzyme productivity. Notably, the specific enzyme productivity was higher in the reduced-genome strain, with or without the rocDEF-rocR region, than in wild-type strain 168. The high specific productivity in strain MGB874 is likely attributable to the higher expression levels of the target gene resulting from an increased promoter activity and plasmid copy number. Thus, the combined effects of the improved cell yield by deletion of the rocDEF-rocR region and the increased specific productivity by deletion of another gene(s) or the genomic reduction itself enhanced the production of recombinant enzymes in MGB874. Our findings represent a good starting point for the further improvement of B. subtilis reduced-genome strains as cell factories for the production of heterologous enzymes.     

Microbacterium terricolae sp. nov., isolated from soil in Japan

The taxonomic positions of two novel strains isolated from a soil sample collected in Japan using Glucose-Peptone-Meat extract (GPM) agar plates supplemented with superoxide dismutase or superoxide dismutase plus catalase were investigated based on the results of chemotaxonomic, phenotypic and genotypic characteristics. Strains were Gram-positive, catalase-positive, non-motile bacteria with L-ornithine as a diagnostic diamino acid of the peptidoglycan. The acyl type of the peptidoglycan was N-glycolyl. The major menaquinones were MK-12 and 13. Mycolic acids were not detected. The G+C content of the DNA was 70 mol%. Comparative 16S rRNA studies on the two isolated strains revealed that they belong to the genus Microbacterium. DNA-DNA relatedness data revealed that KV-448(T) and KV-769 are a new species of the genus Microbacterium. From these results, we propose that these bacteria should be classified in the genus Microbacterium as Microbacterium terricolae sp. nov. The type strain of Microbacterium terricolae is KV-448(T) (=NRRL B-24468(T), NBRC 101801(T)).     

Involvement of up-regulated Necl-5/Tage4/PVR/CD155 in the loss of contact inhibition in transformed NIH3T3 cells

Normal cells show contact inhibition of cell movement and proliferation, but this is lost following transformation. We found that Necl-5, originally identified as a poliovirus receptor and up-regulated in many cancer cells, enhances growth factor-induced cell movement and proliferation. We showed that when cells contact other cells, Necl-5 interacts in trans with nectin-3 and is removed by endocytosis from the cell surface, resulting in a reduction of cell movement and proliferation. We show here that up-regulation of the gene encoding Necl-5 by the oncogene V12-Ki-Ras causes enhanced cell movement and proliferation. Upon cell-cell contact, de novo synthesis of Necl-5 exceeds the rate of Necl-5 endocytosis, eventually resulting in a net increase in the amount of Necl-5 at the cell surface. In addition, expression of the gene encoding nectin-3 is markedly reduced in transformed cells. Thus, up-regulation of Necl-5 following transformation contributes to the loss of contact inhibition in transformed cells.     

The Hes gene family: repressors and oscillators that orchestrate embryogenesis

Embryogenesis involves orchestrated processes of cell proliferation and differentiation. The mammalian Hes basic helix-loop-helix repressor genes play central roles in these processes by maintaining progenitor cells in an undifferentiated state and by regulating binary cell fate decisions. Hes genes also display an oscillatory expression pattern and control the timing of biological events, such as somite segmentation. Many aspects of Hes expression are regulated by Notch signaling, which mediates cell-cell communication. This primer describes these pleiotropic roles of Hes genes in some developmental processes and aims to clarify the basic mechanism of how gene networks operate in vertebrate embryogenesis.     

Pyrazole-O-glucosides as novel Na(+)-glucose cotransporter (SGLT) inhibitors

O-glucuronides and O-glucosides of a series of pyrazoles analogues were synthesized and evaluated for their SGLT inhibitory activity in brush border membrane vehicles (BBMVs) of rat kidney. O-glucosides of certain pyrazole analogues inhibited the transport of [(14)C]-glucose in BBMVs, and induced glucosuria in Wistar rats by intravenous injection.