Targeted disruption of fad24, a regulator of adipogenesis,causes pre-implantation embryonic lethality due to the growth defect at the blastocyst stage

In previous studies, we identified a novel gene, factor for adipocyte differentiation 24 (fad24), which plays an important role during the early stages of adipogenesis in mouse 3T3-L1 cells. Moreover, overexpression of fad24 increased the number of smaller adipocytes in white adipose tissue and improved glucose metabolic activity in mice, thus indicating that fad24 functions as a regulator of adipogenesis in vivo. However, the physiological roles of fad24 in vivo are largely unknown. In this study, we attempted to generate fad24-deficient mice by gene targeting. No fad24-null mutants were recovered after embryonic day 9.5 (E9.5). Although fad24-null embryos were detected in an expected Mendelian ratio of genotypes at E3.5, none of the homozygous mutants developed into blastocysts. In vitro culture experiments revealed that fad24-null embryos develop normally to the morula stage but acquire growth defects during subsequent stages. The number of nuclei decreased in fad24-deficient morulae compared with that in wild-type ones. These results strongly suggested that fad24 is essential for pre-implantation in embryonic development, particularly for the progression to the blastocyst stage.     

Cell Kinetic Study of Human Carcinomas Using Bromodeoxyuridine

Abstract. Cell kinetics in human malignant tumours were studied in vivo using bromodeoxyuridine (BrdU) and immunohistochemistry. BrdU was administered to twenty-four patients with gastric cancer at a dose of 1 g pre-operatively. Specimens were obtained during the operation, fixed in 70% ethanol and embedded in paraffin. BrdU-incorporating cells were detected by immunohistochemical staining using anti-BrdU monoclonal antibody. the labelling index (LI), determined by counting tumour cells microscopically, ranged from 4.0 to 41.4%. the LI was higher at the site of invasion than in the central area of the tumour, but no correlation was found between histological differentiation and LI. the LI of stage I gastric cancer was statistically lower than that of stage II, III and IV gastric cancers (P < 0.005). This technique, which is less cumbersome and time-consuming than using radioactive isotopes of thymidine, appears to be useful for studying cell kinetics of human malignant tumours.     

Involvement of HGF/MET signaling in appendicular muscle development in cartilaginous fish

In amniotes, limb muscle precursors de-epithelialize from the ventral dermomyotome and individually migrate into limb buds. In catsharks, Scyliorhinus, fin muscle precursors are also derived from the ventral dermomyotome, but shortly after de-epithelialization, they reaggregate within the pectoral fin bud and differentiate into fin muscles. Delamination of muscle precursors has been suggested to be controlled by hepatocyte growth factor (HGF) and its tyrosine kinase receptor (MET) in amniotes. Here, we explore the possibility that HGF/MET signaling regulates the delamination of appendicular muscle precursors in embryos of the catshark Scyliorhinus canicula. Our analysis reveals that Hgf is expressed in pectoral fin buds, whereas c-Met expression in fin muscle precursors is rapidly downregulated. We propose that alteration of the duration of c-Met expression in appendicular muscle precursors might underlie the evolution of individually migrating muscle precursors, which leads to the emergence of complex appendicular muscular systems in amniotes.     

The preparation and applications of functional fibres from crab shell chitin

Novel chitin–silk fibroin fibres and chitin fibres were prepared by an environmental friendly wet-spinning method. Each aqueous solution of sodium chitin (N-acetylchitosan) salt and its blends of silk fibroin in aqueous 14% sodium hydroxide was spun through a viscose-type spinneret into an aqueous 10% sulfuric acid solution saturated with ammonium sulfate (about 43%), and the corresponding white filament was obtained. The tenacity and elongation values of the chitin–silk fibroin filament decreased with an increase of fibroin content up to 33% by weight. A scanning electron microscopy analysis revealed that both the chitin filament and the chitin–silk fibroin (67:33, w/w) filament had vertical strips with faint scale structures on their surfaces. Some applications of these staple fibres were also reported.     

Ezetimibe Promotes Brush Border Membrane-to-Lumen Cholesterol Efflux in the Small Intestine

Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1), an apical membrane cholesterol transporter of enterocytes, thereby reduces intestinal cholesterol absorption. This treatment also increases extrahepatic reverse cholesterol transport via an undefined mechanism. To explore this, we employed a trans-intestinal cholesterol efflux (TICE) assay, which directly detects circulation-to-intestinal lumen ³H-cholesterol transit in a cannulated jejunal segment, and found an increase of TICE by 45%. To examine whether such increase in efflux occurs at the intestinal brush border membrane(BBM)-level, we performed luminal perfusion assays, similar to TICE but the jejunal wall was labelled with orally-given ³H-cholesterol, and determined elevated BBM-to-lumen cholesterol efflux by 3.5-fold with ezetimibe. Such increased efflux probably promotes circulation-to-lumen cholesterol transit eventually; thus increases TICE. Next, we wondered how inhibition of NPC1L1, an influx transporter, resulted in increased efflux. When we traced orally-given ³H-cholesterol in mice, we found that lumen-to-BBM ³H-cholesterol transit was rapid and less sensitive to ezetimibe treatment. Comparison of the efflux and fractional cholesterol absorption revealed an inverse correlation, indicating the efflux as an opposite-regulatory factor for cholesterol absorption efficiency and counteracting to the naturally-occurring rapid cholesterol influx to the BBM. These suggest that the ezetimibe-stimulated increased efflux is crucial in reducing cholesterol absorption. Ezetimibe-induced increase in cholesterol efflux was approximately 2.5-fold greater in mice having endogenous ATP-binding cassette G5/G8 heterodimer, the major sterol efflux transporter of enterocytes, than the knockout counterparts, suggesting that the heterodimer confers additional rapid BBM-to-lumen cholesterol efflux in response to NPC1L1 inhibition. The observed framework for intestinal cholesterol fluxes may provide ways to modulate the flux to dispose of endogenous cholesterol efficiently for therapeutic purposes.     

Complete genome sequence of Oscillibacter valericigenes Sjm18-20T (=NBRC 101213T)

Oscillibacter valericigenes is a mesophilic, strictly anaerobic bacterium belonging to the clostridial cluster IV. Strain Sjm18-20^T (=NBRC 101213^T =DSM 18026^T) is the type strain of the species and represents the genus Oscillibacter Iino et al. 2007. It was isolated from the alimentary canal of a Japanese corbicula clam (Corbicula japonica) collected on a seacoast in Shimane Prefecture in Japan. Phylogenetically, strain Sjm18-20^T is closest to uncultured bacteria in digestive tracts, including the enriched cells thought to represent Oscillospira guilliermondii Chatton and Perard 1913. The isolated phylogenetic position and some distinct characteristics prompted us to determine the complete genome sequence. The 4,410,036 bp chromosome and the 60,586 bp plasmid were predicted to encode a total of 4,723 protein-coding genes.     

Chitosan staple fibers and their chemical modification with some aldehydes

Nine wet-spinning conditions were examined for the preparation of chitosan staple fibers, and novel five N-alkylidene and N-arylidene-chitosan staple fibers were obtained by the post-treatment of the chitosan fibers with aldehydes including vanillin. The tenacity and elongation values of the chitosan filaments were almost unchanged by their post-treatment with monoaldehydes except that with formaldehyde and glyoxal. However, these values decreased significantly in the partially N-modified filaments, which were obtained by the pre-treatment with vanillin. The chitosan filaments (31–79 μm in diameter) had a scaly structure on the filament surface as examined by SEM observation.