Cryopreservation of the semen collected by electroejaculation from the Hokkaido brown bear (Ursus arctos yesoensis)

Four adult Hokkaido brown bears were used as semen donors, and semen characteristics were examined before freezing and after thawing. A total of 10 electroejaculates were diluted with Tris-egg yolk extender and cooled to 4 degrees C over 90 min. Spermatozoa were equilibrated with 4.7% glycerol for 80 min. Semen packed in 0.25 ml plastic straws were frozen with liquid nitrogen vapor. Percentages (mean +/- SD) of motile and live sperm were 96+/-2 and 86.5+/-7.2% before freezing, and 43+/-5 and 67.4+/-3.9% after thawing, respectively. Although the number of progressively motile sperm after thawing varied among samples (1.8+/-1.2 x 10(8) cells/ejaculate), frozen semen in the present study might serve for artificial insemination.     

Serum leptin levels during the periparturient period in cows

Serum leptin concentrations were measured in antenatal and postnatal cows housed at two different locations. The mean serum leptin concentration was 9.2 +/- 0.6 ng/m l (n=22) in one group, and was slightly lower in the other (7.4 +/- 0.4 ng/ml, n=54), probably because of the different nutritional conditions between the two groups. There was no consistent variation in relation to the menstrual cycle and the periparturient period in both groups. Moreover, serum leptin concentrations during the periparturient period were independent of the number of delivery and the incidence of mastitis and milk fever. These results are quite different from those in rodents and human, suggesting the different regulatory mechanism of circulating leptin concentration in cows.     

中国南部天然常绿阔叶林的地上生物量、净初级生产力、养分分布和养分利用效率

在中国南部的江西九连山自然保护区,观测研究了天然常绿阔叶林的地上生物量、地上NPP(净初级生产力)、养分的积累和分布,以及不同生活型树种的养分利用效率.在两个样地,用相对生长回归法和收获法测定了地上生物量,数值各约为340和270t/hm2,其中叶生物量约为9.6t/hm2.地上NPP约为年9.9t/hm2,其中叶生产力占44％.各种一般养分(N,P,K,Ca,Mg,Na)在森林生态系统中积累的特点是,Na和N在矿质土壤中有高的相对分布,K和Mg属中间地位,Ca和P则高分布于地上生物量中.氮的养分利用效率(NUE)、平均停留时间(MRT)和年生产力(A)表明,针叶树是氮的最高效的利用者,常绿阔叶树次之,落叶树在氮的利用上是最低效的.     

Interannual variation of the diet shifts and their effects on the fatness and growth of age‐0 Pacific bluefin tuna (Thunnus orientalis) off the southwestern Pacific coast of Japan

We investigated the effect of feeding habits on the fatness (length–weight relationship (LW)) and otolith growth of age‐0 Pacific bluefin tuna (PBF) (fork length (FL) of 15.0–29.9 cm) collected off the southwestern Pacific coast of Japan from July to August during 2010–2015. The feeding rate on Clupeiformes (FRc) was substantially influenced by the path of the Kuroshio Current during early summer. We suggest that the following patterns occurred in the feeding habits of PBF. In 2012 and 2014, the short distance from the coast to the Kuroshio provided high overlap between PBF and Clupeiformes and increased the opportunity for feeding, and this pattern likely caused the observed diet shift from Crustacea to Clupeiformes by smaller PBF in the studied years than those in other years. In 2011 and 2015, the encounter probability for Clupeiformes might have been low due to the long distance to the Kuroshio Current, which led PBF to actively consume non‐Clupeiformes Teleostei. In contrast, in August 2010 and 2015, PBF did not encounter Clupeiformes or other Teleostei and may have been forced to feed on a large number of Crustacea; this effect was likely due to high water temperatures. Despite the interannual fluctuation in the timing of the diet shift and the feeding intensity (FI), these factors did not contribute to growth in length; rather, they contributed to fatness. Considering size‐dependent mortality in the larval stage, these results suggest that only fast‐growing individuals survive, even if the feeding conditions drastically change.     

Deformation and blemishing of pearls caused by bacteria

Bacteria cause deformation and blemishing in pearls, and we investigate this relationship. We examined pearls derived from Pinctada margaritifera, Pinctada maxima, and Pinctada fucata, and determined the location of bacteria using histopathological and immunohistochemical techniques and 16S ribosomal RNA (rRNA) sequence analyses. The most remarkable change was the inflammatory reaction located between the pearl nucleus and the nacreous layer, composed of hemocytic infiltration with melanization, periostracum, and fibrous aragonite-like structures. These anomalous changes were limited to abnormal sites, and such inflammatory reaction sites are a major factor in the formation of pearl abnormalities. Bacteria were detected from the inflammatory sites and are suspected as the causative agent. Most of these bacteria were anaerobic.     

Age validation,growth and annual reproductive cycle of chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> off the waters of northern Kyushu and in the East China Sea

The age and growth of chub mackerel Scomber japonicus collected from the East China Sea and the northern waters off Kyushu between June 2000 and June 2001 were determined by observing the otolith surface after dipping it in xylene. The translucent and opaque zones on the otolith surface were identified, and the number of translucent zones was counted. Monthly changes in the frequency of fish with translucent zones on the otolith margin, and in the marginal increments, indicated that the translucent zones were formed between April and June. The seasonal pattern of annulus formation on the otolith became clear by observing the otoliths of fish with known ages, and the otolith formation in wild fish was consistent with that of fish with known ages. The mean gonadosomatic index of male and female fish was high from March to May, and spawning females were observed from mid-March to mid-May. The estimated ages were 1–5 years for males and 1–6 years for females. The von Bertalanffy growth parameters did not significantly differ between male and female. The model was obtained as FL _t=406×{1−exp[−0.372×(t+1.68)]     

Age, growth, and reproductive characteristics of dolphinfish Coryphaena hippurus in the waters off west Kyushu, northern East China Sea

The growth and reproductive characteristics of dolphinfish Coryphaena hippurus collected in the waters off western Kyushu from May 2008 to April 2011 were determined based on scale and otolith readings and gonad histological examinations, respectively. Based on annual increments in scales and daily increments in sagittal otoliths, the von Bertalanffy growth curves in male and females were determined as $ FL_{t} = 1049[1 - \exp \{ - 0.835(t + 6.975 \times 10^{ - 14} )\} ] $ and $ FL_{t} = 938[1 - \exp \{ - 1.029(t + 6.975 \times 10^{ - 14} )\} ] $ , respectively, where FL _t is the mean fork length (mm) at age t. The spawning period was found to last from June to August for dolphinfish, based on an examination of the monthly changes in the gonadosomatic index and histological observations. Therefore, based on the relationship between the fork length and the developmental stage of the testes or ovaries, male and female dolphinfish were found to reach sexual maturity by the following spawning season after hatching in the northern East China Sea.     

Expression and localization of estrogen receptors α and β mRNA in medullary bone of laying hens

The aim of this study was to observe the expression and localization of estrogen receptor (ER) α and ER β mRNA in the medullary bone of laying hens. First, medullary bone, liver, kidney, and shell gland of the oviduct tissues were dissected from laying hens. Then, the total cellular RNA was isolated from each tissue specimen, and the ER α and ER β mRNA expression was observed using semiquantitative RT‐PCR. Second, the localization of ER α mRNA in the medullary bone was detected with in situ hybridization using digoxigenin‐11‐UTP‐labeled cRNA probes. As a result, the expression of ER α mRNA was higher than that of ER β mRNA in the medullary bone, liver, and shell gland of the oviduct from laying hens. In the kidney, ER α mRNA expression was lower than that of ER β mRNA. The expression pattern of ER α and ER β mRNA of the medullary bone was similar to that of the shell gland of the oviduct. Moreover, ER α mRNA was intensively expressed in osteoblasts on the medullary bone surface and bone marrow stromal cells but was not expressed in osteoclasts. These results suggest that in medullary bone, estrogen action may be regulated not by ER β but by ER α.