Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations

Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.     

Two-decadal trends in aboveground litterfall and net primary production in self-thinning Pinus banksiana stands in Wood Buffalo National Park,NWT, Canada

We estimated the aboveground net primary production (ANPP) in five self-thinning jack pine (Pinus banksiana) stands in Wood Buffalo National Park, NWT, Canada. The stands (11 to ca.175 years old) were selected to examine the relationship between stand density and tree size and its effect on carbon dynamics. Aboveground litterfall was collected from each stand from 1997 to 2012. Stand biomass was estimated by measuring tree size every 5 years and estimating the individual mass using allometric relationships. ANPP was then estimated by summing the litterfall mass, dead stem mass increment and stand biomass increment. We determined the proportional contribution of each organ to the total litter and the seasonal pattern of needle litterfall. There was a lower turnover rate of aboveground biomass in older stands than younger stands. The ANPP increased in the youngest stand (<30 years old) showed a decreasing trend in stands >50 years old. The maximum ANPP was estimated to be ca. 500?g m^?2 year^?1 in dry matter, which was found in 30–50 year-old stands.     

A basic study of chemotaxis of leptospiras

Chemotaxis of leptospiras was studied using a U-tube made of a commercially available straw-shaped polypropylene tube with an uneven flexible part. The U-tube was made by folding the polypropylene tube double and binding the vertical parts by a piece of tape, thus making the uneven flexible part the bottom. Semi-solid Korthof's medium was poured into the U-tube. Preliminary experiments showed that the medium containing 0.5% agar and measuring 2 cm in in length was appropriate. Leptospiras inoculated on the top of the medium of one side of the U-tube moved toward the top of the medium of the other side. The leptospiral move toward the uninoculated top was significantly faster when 6 micrograms of hemoglobin were added to the uninoculated top. Chemotaxis of leptospiras to hemoglobin was thus shown, which is the first evidence of chemotaxis of leptospiras.     

Adhesion of Corynebacterium pilosum by pili to epithelial cells of bovine vulva

Piliated (P+) and nonpiliated (P-) clones of Corynebacterium pilosum were selected, and their adhesion to the epithelial cells of the bovine vulva and vaginal vestibule was examined. The number of P+ bacteria of C pilosum that adhered to vulval epithelial cells was greater than that of P- bacteria. The adhesion of P+ bacteria, but not P- bacteria, to the epithelial cells was inhibited by the antipilus antiserum; therefore, the adhesion of C pilosum to the epithelial cells of the vulva was primarily dependent on the pili. The number of C pilosum that adhered to the epithelial cells of the bovine vulva and of the vaginal vestibule increased by decreasing the pH.     

Effects of follicle‐stimulating hormone followed by gonadotropin‐releasing hormone on embryo production by ovum pick‐up and in vitro fertilization in the river buffalo (Bubalus bubalis)

In this study, we examined the effects of superstimulation using follicle‐stimulating hormone (FSH) followed by gonadotropin‐releasing hormone (GnRH) on buffalo embryo production by ultrasound‐guided ovum pick‐up (OPU) and in vitro fertilization (IVF). Nine Murrah buffaloes were subjected to OPU‐IVF without superstimulation (control). The morphologies of the oocytes collected were evaluated, and oocytes were then submitted to in vitro maturation (IVM). Two days after OPU, same nine buffaloes were treated with twice‐daily injections of FSH for 3 days for superstimulation followed by a GnRH injection. Oocytes were collected by OPU 23–24 hr after the GnRH injection and submitted to IVM (the superstimulated group). The total number of follicles, number of follicles with a diameter > 8 mm, and number of oocytes surrounded by multi‐layered cumulus cells were higher in the superstimulated group than in the control group (p ≤ 0.05). After IVF, the percentages of cleavage and development to blastocysts were higher in the superstimulated group than in the control group (p < 0.05). In conclusion, superstimulation improved the quality of oocytes and the embryo productivity of OPU‐IVF in river buffaloes.