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101.
Composition and structure of the main forest types, as well as the species changes under disturbance, were described as the
representation of the forest vegetation in the north slope of Changbai mountain, northeast China. There were 3 forest zones
from 600 m to 2,000 m asl, (1) broad-leaved-conifer mixed forest zone, 600–1,100 m asl, dominated byPinus koraiensis, Tilia amurensis, Acer mono, Ulmus japonica, (2) coniferous forest zone, 1,100–1,700 m asl, dominated byPicea jezoensis var.komarovii, P. koraiensis, Abies nephrolepis, and (3)Betula ermanii forest zone, 1,700–2,000 m asl, dominated byBetula ermanii, except for the east slope which was occupied byLarix olgensis. The evergreen component increased with elevation up to the upper limit of the coniferous forest zone (1,700 m), but disappeared
in theB. ermanii zone. Species richness was significantly related to elevation. Towards higher elevation, the lapse rate of species-number
was 1.6 species per 100 m, and it was only one species near the timberline. Species richness was reduced sharply under intensive
disturbance, such as clear cutting, windfalletc. The species diversity was very low in the early stage of succession, and high in the later. 相似文献
102.
103.
Nyuji M Selvaraj S Kitano H Ohga H Yoneda M Shimizu A Kaneko K Yamaguchi A Matsuyama M 《Fish physiology and biochemistry》2012,38(3):883-897
The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively. We applied a quantitative real-time PCR assay to quantify the mRNA expression levels of these GtH subunits. During the seasonal reproductive cycle, FSHβ mRNA levels remained high during the vitellogenic stages, while GPα and LHβ mRNA levels peaked at the end of vitellogenesis. The expression of all three GtH subunits decreased during the post-spawning period. These results suggest that follicle-stimulating hormone (FSH) is involved in vitellogenesis, while luteinizing hormone (LH) functions during final oocyte maturation (FOM). Both GPα and FSHβ mRNA levels remained high during the FOM stages of the spawning cycle and increased further just after spawning. Thus, FSH synthesis may be strongly activated just after spawning to accelerate vitellogenesis in preparation for the next spawning. Alternatively, LHβ mRNA levels declined during hydration and then increased after ovulation. This study demonstrates that chub mackerel are a good model for investigating GtH functions in multiple spawning fish. 相似文献
104.
Akihiko Ebisawa 《Fisheries Science》2013,79(6):911-921
The life history of the leopard coralgrouper Plectropomus leopardus was examined for the purpose of stock evaluation and to help maintain populations in the Okinawa Islands, southwestern Japan. Age was estimated from cut and burnt otoliths, and gonads were observed histologically to reveal the growth, spawning period and relationships between age and both sexual development and sexual maturation for P. leopardus in waters north of Okinawa Island. The three parameters in the von Bertalanffy growth equation, L ∞ , k, and t 0, were estimated at 61.2 cm fork length, 0.289, and 0.41, respectively. The oldest individual obtained among the specimens was 18.8 years. The spawning period started in May and lasted until July. During this period, 50 % of females reached maturity at 43.3 cm fork length and at 5 years of age. Due to the sexual transition from female to male, the sex ratio decreased to 50 % at 59.8 cm fork length and at 10.3 years of age. 相似文献
105.
Yonekura S Sakamoto K Komatsu T Hagino A Katoh K Obara Y 《Domestic animal endocrinology》2006,31(1):88-96
Leptin mRNA is expressed in not only adipocytes but also mammary epithelial cells and leptin protein is present in milk. Although milk leptin is thought to influence metabolism or the immune system in neonates, there is little information about the regulation of leptin expression in mammary epithelial cells. We examined the effect of growth hormone (GH) and/or lactogenic hormone complex (DIP; dexamethasone, insulin and prolactin) on leptin mRNA expression in mammary epithelial cells. We used a bovine mammary epithelial cell (BMEC) clonal line, which was established from a 26-day pregnant Holstein heifer. We confirmed that the mRNA was expressed in BMECs and the expression was significantly reduced by GH and/or DIP, when the cells were cultured on both plastic plates and cell culture inserts at days 2 and 7 after stimulation with lactogenic hormones. GH and/or DIP significantly increased level of alpha-casein mRNA in BMECs after 7 days on the cell culture inserts, but no mRNA expression was detected at day 2. GH and DIP significantly stimulated the secretion of alpha-casein from BMEC on cell culture inserts at 3.5 and 7 days. However, neither alpha-casein mRNA expression nor secretion was observed in the BMECs cultured on plastic dishes, even in the presence of GH or/and DIP. These results indicate that GH and DIP can directly reduce leptin mRNA expression in both undifferentiated and functionally differentiated bovine mammary epithelial cell. 相似文献
106.
Nobuya Tashiro Kayo Manabe Akihiko Saito Kiyotaka Miyashita 《Journal of General Plant Pathology》2012,78(5):353-359
Acid scab of potatoes occurs frequently in strongly acidic soils at pH 3.9–5.2. On the basis of the phylogenetic relationships derived from 16S rDNA sequences and physiological characteristics, we identified the organism causing this disease in potatoes grown in the Uwaba district of Saga Prefecture, Kyushu Island, southwest Japan, as Streptomyces acidiscabies. Another pathogen that occurred more frequently in weakly acidic to neutral soils, rather than strongly acidic soils, was identified as S. scabiei. Streptomyces acidiscabies tended to produce superficial lesions, while S. scabiei mostly produced raised and/or erumpent lesions. 相似文献
107.
Midori Yoshida Shin-ichi Katsuda Akihiko Maekawa 《Journal of toxicologic pathology》2012,25(4):241-247
Involvements of estrogen receptor (ER)α, proliferating cell nuclear antigen (PCNA) and p53
in the uterine carcinogenesis process in Donryu rats, a high yield strain of the uterine cancer
were investigated immunohistochemically. ERα was expressed in atypical endometrial hyperplasia,
accepted as a precancerous lesion of the uterine tumors, as well as well- and in
moderately-differentiated endometrial adenocarcinomas, and the intensities of expression were
similar to those in the luminal epithelial cells of the atrophic uterus at 15 months of age.
The expression, however, was negative in the tumor cells of poorly differentiated type. Good
growth of implanted grafts of the poorly-differentiated adenocarcinomas in both sexes with or
without gonadectomy supported the estrogen independency of tumor progression to malignancy.
PCNA labeling indices were increased with tumor development from atypical hyperplasia to
adenocarcinoma. The tumor cells in poorly-differentiated adenocarcinomas were positive for p53
positive but negative for p21 expression, suggesting accumulation of mutated p53. These results
indicate that the consistent ERα expression is involved in initiation and promotion steps of
uterine carcinogenesis, but not progression. In addition, PCNA is related to tumor development
and the expression of mutated p53 might be a late event during endometrial carcinogenesis. 相似文献
108.
Ayano HIRAKO Jin SUN Satoshi FURUKAWA Takashi TAKEUCHI Akihiko SUGIYAMA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(12):1565-1571
Two-day-old rats were treated with subcutaneous injections of methotrexate (MTX) 5 mg/kg
and 150 mg/kg, and their rostral migratory streams (RMS) were examined time-dependently.
MTX treatment increased pyknotic and TUNEL-positive cells and decreased mitotic and
phospho-Histone H3-positive cells at almost all time points in the vertical arm, elbow and
horizontal arm regions of the RMS. There were more TUNEL-positive cells ratio in the MTX
150 mg/kg group than in the MTX 5 mg/kg group. Treatment with MTX 150 mg/kg decreased the
cellularity in the vertical arm region on Postnatal day (PD) 4, but that with the MTX 5
mg/kg did not. TUNEL-positive cells ratio was the highest in the vertical arm region,
followed by elbow and horizontal regions in both MTX-treated groups. TUNEL-positive cells
ratio in the vertical arm and elbow regions reached their peaks on PD 4 in both
MTX-treated groups, and both MTX-treatments significantly decreased Phospho-Histone
H3-positive cells ratio on PDs 2.5 and 3 in the vertical arm, elbow and horizontal arm
regions. The phospho-Histone H3-positive cells ratio in the vertical arm region recovered
on PD4 in the MTX 150 mg/kg group. These findings suggested that RMS required a great
amount of folic acid on PD 2 and that the folic acid-requirement differed depending on the
anatomical region of the RMS. To our knowledge, this is the first report demonstrating the
effect of MTX on the RMS and the necessity of the folic acid metabolism on RMS development
in newborn rats. 相似文献
109.
110.
Miyako SUGIYAMA Ryoka KAWAHARA-MIKI Hirosuke KAWANA Koumei SHIRASUNA Takehito KUWAYAMA Hisataka IWATA 《The Journal of reproduction and development》2015,61(4):251-259
Mitochondrial numbers increase during oocyte growth. In this study, we collected oocytes and granulosa cell complexes (OGCs) from early antral follicles (EAFs) of aged cows (> 120 months of age) and examined the effects of resveratrol on mitochondrial generation, degradation, and quality in oocytes grown in vitro. We also examined the effects of resveratrol on gene expression of the granulosa cells. Resveratrol (20 µM) enhanced the expression of SIRT1 and induced autophagy in both granulosa cells and oocytes derived from aged cows. Culturing the OGCs with resveratrol increased mitochondrial DNA copy numbers in oocytes grown in vitro. Furthermore, resveratrol increased the ATP content in oocytes and improved the developmental ability of the oocytes to the blastocyst stage. Gene expression profiles in granulosa cells, as evaluated by next-generation sequencing technology, revealed that resveratrol enhanced the expression of EIF2-related
genes but downregulated the expression of mammalian target of rapamycin (mTOR)-, inflammation-, and cholesterol homeostasis-related genes in granulosa cells. In conclusion, resveratrol affected both oocytes and granulosa cells derived from aged cows and improved the quality of oocytes grown in vitro through upregulation of mitochondrial biogenesis and degradation in growing oocytes and conditioning of granulosa cells. 相似文献