Induction of Haploid Androgenesis in Pacific Oyster by UV Irradiation

Androgenesis, development from paternal but not maternal chromosomes, can be induced in some organisms including fish, but has not been induced previously in mollusk. In this study we investigated the induction of haploid androgenesis in the Pacific oyster by ultraviolet irradiation and observed nuclear behavior in the androgenetic eggs. Irradiation for 90 seconds at a UV intensity of 72 erg/mm² per second (6480 erg/mm²) was the optimal dose to achieve haploid androgenesis. The fertilization and development rates of D-shaped larvae decreased with increasing exposure time, and the development of the genetically inactivated eggs terminated before reaching the D-shaped stage. Cytologic observations showed that UV irradiation did not affect germinal vesicle breakdown or chromosomal condensation but caused various nuclear behavioral patterns during meiosis and first mitosis: 21.7% of eggs extruded all maternal chromosomes as 2 or 3 polar bodies, and 59.1% of eggs formed one female pronucleus. The maternally derived nucleus did not participate, or partially participated, in the first karyokinesis. The cytologic evidence demonstrates that the male genome is directing development in haploids produced by UV irradiation.     

Protein kinase C delta regulates the phosphorylation of heat shock protein 27 in human hepatocellular carcinoma

We have recently reported that attenuated phosphorylation of heat shock protein (HSP) 27 correlates with tumor progression in patients with hepatocellular carcinoma (HCC). In the present study, we investigated what kind of kinase regulates phosphorylation of HSP27 in human HCC-derived HuH7 cells. 12-O-tetradecanoylphorbol-13-acetate (TPA) and 1-oleoyl-2-acetylglycerol, direct activators of protein kinase C (PKC), markedly strengthened the phosphorylation of HSP27. Bisindorylmaleimide I, an inhibitor of PKC, suppressed the TPA-induced levels of HSP27 phosphorylation in addition to its basal levels. Knock down of PKCdelta suppressed HSP27 phosphorylation, as well as p38 mitogen-activated protein kinase (MAPK) phosphorylation. SB203580, an inhibitor of p38 MAPK, suppressed the TPA-induced HSP27 phosphorylation. Our results strongly suggest that activation of PKCdelta regulates the phosphorylation of HSP27 via p38 MAPK in human HCC.     

Induction of human beta-defensin-2 mRNA expression by Helicobacter pylori in human gastric cell line MKN45 cells on cag pathogenicity island.

Helicobacter pylori is an etiological agent of gastritis, peptic ulcer, and gastric cancer. Human beta-defensin-2 (hBD-2) is an antimicrobial peptide which belongs to one of the most important host defense systems against bacterial infection in several epithelial tissues. We studied the effect of H. pylori on the expression of hBD-2 mRNA in MKN45 gastric mucosal cells. H. pylori, but not culture filtrate, increased the hBD-2 mRNA level in MKN45 cells; the inductive effect of H. pylori was not detected with Intestine 407 cells. Among H. pylori strains, strain OHPC0002, which lacks a cag Pathogenicity Island (PAI), did not induce hBD-2 mRNA in MKN45 cells. These results suggested that H. pylori cag PAI is critical for the induction of hBD-2 mRNA in MKN45 cells. Exposure of MKN45 cells to Salmonella typhimurium, S. enteritidis, S. typhi, and S. dublin, but not Escherichia coli ML35, also resulted in induction of hBD-2 mRNA.     

Identification and expression of a sialyltransferase responsible for the synthesis of disialylgalactosylgloboside in normal and malignant kidney cells: downregulation of ST6GalNAc VI in renal cancers

Although disialyl glycosphingolipids such as GD3 and GD2 have been considered to be associated with malignant tumours, whether branched-type disialyl glycosphingolipids show such an association is not well understood. We investigated the sialyltransferases responsible for the biosynthesis of DSGG (disialylgalactosylgloboside) from MSGG (monosialylgalactosylgloboside). Among six GalNAc:alpha2,6-sialyltransferases cloned to date, we focused on ST6GalNAc III, V and VI, which utilize sialylglycolipids as substrates. In vitro enzyme analyses revealed that ST6GalNAc III and VI generated DSGG from MSGG with V(max)/K(m) values of 1.91 and 4.16 respectively. Transfection of the cDNA expression vectors for these enzymes resulted in DSGG expression in a renal cancer cell line. Although both ST6GalNAc III and VI genes were expressed in normal kidney cells, the expression profiles of ST6GalNAc VI among 20 renal cancer cell lines correlated clearly with those of DSGG, suggesting that the sialyltransferase involved in the synthesis of DSGG in the kidney is ST6GalNAc-VI. ST6GalNAc-VI and DSGG were found in proximal tubule epithelial cells in normal kidney tissues, while they were downregulated in renal cancer cell lines and cancer tissues. All these findings indicated that DSGG was suppressed during the malignant transformation of the proximal tubules as a maturation arrest of glycosylation.     

Where Do Neurologists Look When Viewing Brain CT Images? An Eye-Tracking Study Involving Stroke Cases

The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the "bottom-up salience" form of visual attention, although the neurologists more effectively used the "top-down instruction" form.     

A missense mutant myostatin causes hyperplasia without hypertrophy in the mouse muscle

Myostatin, which is a member of the TGF-beta superfamily, is a negative regulator of skeletal muscle formation. Double-muscled Piedmontese cattle have a C313Y mutation in myostatin and show increased skeletal muscle mass which resulted from an increase of myofiber number (hyperplasia) without that of myofiber size (hypertrophy). To examine whether this mutation in myostatin gene affects muscle development in a dominant negative manner, we generated transgenic mice overexpressing the mutated gene. The transgenic mice exhibited dramatic increases in the skeletal muscle mass resulting from hyperplasia without hypertrophy. In contrast, it has been reported that a myostatin mutated at its cleavage site produces hypertrophy without hyperplasia in the muscle. Thus, these results suggest that (1) the myostatin containing the missense mutation exhibits a dominant negative activity and that (2) there are two types in the dominant negative form of myostatin, causing either hypertrophy or hyperplasia.     

Accelerating Effect of Soy Peptides Containing Collagen Peptides on Type I and III Collagen Levels in Rat Skin

Two weeks of feeding soy peptides containing 2% collagen peptides increased the levels of type I and III tropocollagen and their mRNAs. In contrast, the diet did not increase the mRNA levels of rat hyaluronan synthases, serine palmitoyltransferase (the rate-limiting enzyme of ceramide synthesis), and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (the key enzyme of cholesterol synthesis). These results suggest that feeding of soy peptides with collagen peptides specifically enhanced the tropocollagen level in the skin.     

A New Screening Method of Viral-neuraminidase Inhibitors

A new and practical method for the screening of neuraminidase inhibitors (NI) by means of the viral hemagglutination (HA)-dehemagglutination(deHA) reactions was suggested. The best conditions for the HA and deHA reactions were investigated. Existence of strong inhibition activity on the viral deHA has been recognized in the culture filtrates of some strains of actinomycetes. All of these deHA inhibitors showed NI activity that is not specified to the strain of the test viruses. About 0.25 mg/ml of the preparation obtained from the culture filtrate of the strongest actinomycetes, No. 289, inhibited the liberation of neuraminic acid from bovine submaxillary mucin by 80 HA units/ml of influenza A Fukuoka/1/70 (H₃N₂) virus up to 80%.     

Sugar Specificity in the Induction and on the Activity of Streptomyces α-d-Galactosidases

The α-d-galactosidases of six Streptomyces strains were examined on their inducer susceptibility, substate specificity, and inhibitor susceptibility. In all strains examined, α-d-galactosidase was induced by d-galactose, but neither by d-fucose nor by l-arabinose. α-d-Fucosidase activity was always induced accompanying with α-d-galactosedase activity. β-l-Arabinosidase activity, however, was never observed. These α-d-galactosidases were purified to electrophoretically pure degree by successive ammonium sulfate and ethanol precipitation, and ion exchange and gel filtration chromatography. The purified preparations from six strains were different from each other in their chromatographic behaviors and in some physical properties, but they all showed strong α-d-fucosidase activity as well. The α-d-galactosidase activities were strongly inhibited by d-galactose and l-arabinose, but scarcely by d-fucose. On the other hand, their α-d-fucosidase activities were inhibited by d-fucose as well as by d-galactose and l-arabinose.