Biomedical subjects

Takeshi Kitano

Publications and source records attributed to Takeshi Kitano.

4 recordsLinked to original sources

PubMed2002

Promotion of cathepsin L activity in newt spermatogonial apoptosis induced by prolactin.

We previously showed that prolactin (PRL) induces apoptosis in newt secondary spermatogonia and indicated that caspase activity is involved in the apoptosis. Since it was recently reported that Z-VAD-fmk, a pan-caspase inhibitor, blocks activity of cysteine cathepsins as well, we examined whether cathepsin is involved in the newt spermatogonial apoptosis. We found cathepsin L activity in the testis that was elevated by PRL in organ culture of testis, while E-64d, a lysosomal cysteine protease inhibitor, and Z-VAD-fmk suppressed it and chromosomal condensation. These results suggest that cathepsin L activity play a pivotal role in PRL-induced spermatogonial apoptosis.

Animals↗

PubMed2002

Oocyte apoptosis during the transition from ovary-like tissue to testes during sex differentiation of juvenile zebrafish.

Large numbers of apoptotic early diplotene oocytes were observed during the transition from ovary-like undifferentiated gonadal tissue to testes during sex differentiation in presumptive males of the zebrafish (Danio rerio). The percentage of terminal-deoxynucleotidyl-transferase-mediated dUTP nick-end labelling (TUNEL)-positive apoptotic oocytes in the gonads of presumptive males was approximately eight- to 12-fold higher than in genetic all-females. By 29 days post-hatching, all oocytes had disappeared from the gonads of presumptive males. In these males, we also observed apoptotic somatic cells in the ovarian cavity between 23 and 35 days post-hatching. Therefore, the disappearance of oocytes and the decomposition of the ovarian cavity caused by apoptosis during sex differentiation were male-specific events. In genetic all-females, apoptosis in a proportion of early diplotene oocytes was found in the undifferentiated gonads at 15-19 days post-hatching, probably as a result of programmed oocyte loss during ovarian development. These findings suggest that oocyte apoptosis is the mechanism of testicular and ovarian differentiation in zebrafish.

Animals↗

PubMed2002

Purification and identification of a tributyltin-binding protein from serum of Japanese flounder, Paralichthys olivaceus.

Tributyltin (TBT) is an industrial chemical used as an antifoulant in marine environments. Previously, we reported that TBT accumulates in the serum or plasma of some fishes and is bound to a high molecular weight compound in the serum of the Japanese flounder, Paralichthys olivaceus. In this study, we succeeded in purifying the TBT-binding protein (TBT-bp) from the serum of Japanese flounder by using gel filtration chromatography, anion exchange chromatography, and polyacrylamide gel electrophoresis, with a 2.6% yield and a 77-fold purification. The molecular mass of TBT-bp was approximately 46.5 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its isoelectric point was approximately 3.0 on isoelectric focusing-polyacrylamide gel electrophoresis. The TBT-bp contained 42% N-glycan. The cDNA nucleotide sequence of TBT-bp was determined by reverse transcription-polymerase chain reaction of Japanese flounder liver, and we deduced a sequence of 191 amino acids of mature TBT-bp. No sequence identical to the TBT-bp amino acid sequence was found within the SWISS-PROT (http://www.nig. ac.jp/) protein database; however, a lipocalin-like sequence pattern was observed. We concluded that the TBT-bp was a novel protein that has not yet been reported, although some DNA sequences from expressed sequence tags (ESTs) of Japanese flounder liver had a high identity. A high expression level of TBT-bp gene was found in the liver, but the gene was slightly detectable in the kidney and brain.

Amino Acid Sequence↗

PubMed2000

Electron paramagnetic resonance study utilizing stripping method on normal human stratum corneum.

BACKGROUND/AIM: Electron paramagnetic resonance (EPR) spectra of nitroxide spin probes are useful for studying biological membranes, and chemical-membrane interaction. The objective of this study was to assess the fluidity of stripped stratum corneum (SC) of normal human skin with EPR. METHODS: We quantified the fluidity of stripped SC (S-SC) by a single stripping with cyanoacrylate onto quartz glass, cover glass or transparent film. Spectra were compared with those of the SC of cadaver skin (C-SC). RESULTS: All S-SC spectra were similar to those of C-SC. There were no statistical differences in the order parameters S between C-SC and those on quartz cell and cover glass, but those of transparent film were significantly higher. Spectra after a month storage at room temperature at 5 degrees C and at -20 degrees C were unchanged. The order parameter S had decreased after a 3-month storage in all conditions. CONCLUSION: This method is useful for the evaluation of the fluidity measurement utilizing EPR spectra of S-SC.

Journal Article↗