Characteristics of Kiso Ultra-Violet Excess Galaxies

We examined the general characteristics of the Kiso Ultra-violet Excess Galaxies (KUGs). We present for the first time the quantitative expressions for the criteria of the KUGs; the boundary color separating the KUGs from the non-KUGs is (B-V)_{T} = 0.74 and the KUG degrees of UV strength are found to correlate with the mean (B-V)_{T} colors. We investigate the nature of the KUGs, a sample of blue galaxy population, and show that (1) about a half of the KUGs are spiral galaxies with Sb to Scd, (2) the KUGs are biased to late-type galaxies and include early-type galaxies with young star populations, and (3) the KUGs are preferably found among less luminous galaxies with log L(B) < 10. The KUGs also contain the post-starburst galaxies, many of which are found among the blue galaxy population at intermediate redshifts. The analysis of the far-infrared data shows that a typical present-to-past star formation rate for a KUG is 0.4.Comment: Revised version of astro-ph/9706088, accepted manuscript for AJ; uuencoded gzip'ed tar'ed file containing 25 files; a manuscript (aasms4), 7 tables (aj_pt4), 17 PS figures; To be appeared in The Astronomical Journal, Vol. 114, No. 5 (1997 November issue

Photometric Observations of Star Formation Activity in Early Type Spirals

We observationally study the current star formation activities of early type spiral galaxies. We construct a complete sample of 15 early type spirals having far-infrared (FIR) to optical B band luminosity ratios, L(FIR)/L(B), larger than the average of the type, and make their CCD imaging of the R and H-alpha bands. The equivalent widths of H-alpha emission increase with increasing L(FIR)/L(B), indicating that L(FIR)/L(B) can be an indicator of star formation for such early type spirals with star formation activities higher than the average. For all of the observed early type spirals, the extended HII regions exist at the central regions with some asymmetric features. H-alpha emission is more concentrated to the galactic center than the R band light, and the degree of the concentration increases with the star formation activity. We also analyze the relation between the star formation activities and the existence of companion galaxies in the sample galaxies and other bright early type spirals. No correlation is found and this suggests that the interaction is not responsible for all of the star formation activities of early type spirals.Comment: LaTex, 23 pages (2 tables included), plus 9 Postscript figures & 1 table. To be published in AJ (November issue

Behavior of ACRBP-deficient mouse sperm in the female reproductive tract

Gene-knockout mice lacking ACRBP, a proacrosin-binding protein localized in the acrosome of sperm, have been shown to exhibit male subfertility, owing to abnormal formation of the acrosome. In this study, to elucidate the mechanism contributing to the subfertility phenotype, we examined the behavior of ACRBP-deficient mouse sperm in the female reproductive tract. When sperm that had migrated into the uterus and oviduct after mating were counted, the number of ACRBP-deficient sperm was noticeably smaller in the oviduct of mice post mating. However, ACRBP-deficient sperm recovered from the oviduct possessed morphologically normal head shape and retained normal motility. Importantly, ACRBP-deficient sperm displayed a marked reduction in the ability to successfully gain access to unfertilized oocytes. These data suggest that male subfertility of ACRBP-deficient mice may be attributed to incompleteness of the acrosome reaction rather than impairment in sperm migration from the uterus to the oviduct