Effects of photoperiod on gonadotropin-releasing hormone levels in the brain and pituitary of underyearling male barfin flounder   总被引：2，自引：0，他引：2  

Masafumi  AMANO  Takeshi  YAMANOME  Hideaki  YAMADA  Koichi  OKUZAWA  Kunio  YAMAMORI 《Fisheries Science》2004,70(5):812-818

ABSTRACT:   A pleuronectiform fish, the barfin flounder Verasper moseri , expresses three gonadotropin-releasing hormone (GnRH) forms in the brain: salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II) and seabream GnRH (sbGnRH). To clarify the effects of photoperiod on GnRH systems, changes in brain and pituitary GnRH peptide levels were examined using time-resolved fluoroimmunoassays. In experiment 1, 5-month-old male barfin flounder (mean total length 9.0 cm, body weight 11.0 g) were divided into short (8:16 h light : dark [L:D] cycle; lights on 08.00–16.00 hours) and long photoperiod (16:8 h L:D cycle; lights on 04.00–20.00 hours) groups in mid September and maintained until November under natural water temperature (19.3–15.2°C). Brain sGnRH concentrations were significantly higher in the 16:8 h L:D group than in the 8:16 h L:D group, whereas no significant differences were observed in total length, body weight, plasma testosterone concentration, brain cGnRH-II concentration and pituitary sbGnRH content. In experiment 2, 7-month-old male barfin flounder (mean total length 16.5 cm, body weight 76.8 g) were divided into short and long photoperiod groups in mid December and maintained until February under natural water temperature (12.5–6.6°C). Total length, body weight and condition factor were significantly greater in the 16:8 h L:D group than in the 8:16 h L:D group, whereas no significant differences were observed in plasma testosterone concentration and GnRH levels in the brain and pituitary. These results indicate that levels of sGnRH in barfin flounder are influenced by photoperiodic treatment dependent on water temperature and/or body size.  相似文献   

Nutrient digestibility values of a test diet determined by manual feeding and self-feeding in rainbow trout and common carp     

Takeshi Yamamoto  Takao Shima  Hirofumi Furuita  Nobuhiro Suzuki  Manabu Shiraishi 《Fisheries Science》2001,67(2):355-357

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Effect of taurine supplemented practical diet on growth performance and taurine contents in whole body and tissues of juvenile Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>     

Shin-Kwon?Kim  Toshio?TakeuchiEmail author  Atsushi?Akimoto  Hirofumi?Furuita  Takeshi?Yamamoto  Masahito?Yokoyama  Yuko?Murata 《Fisheries Science》2005,71(3):627-632

ABSTRACT:   The effect of dietary taurine on juvenile Japanese flounder was determined by feeding three taurine-supplemented experimental diets (TAU) and a commercial diet (CD) to evaluate a practical diet for juvenile Japanese flounder. Juvenile Japanese flounder were reared on the three experimental diets supplemented with taurine at 0, 0.5, 1.0% and CD. These diets were fed to juvenile Japanese flounder of an initial mean body weight of 0.2 g for 6 weeks at 20°C and the taurine contents of the whole body and tissues were analyzed. The final average body weight of juvenile Japanese flounder fed the 1.0% TAU was significantly higher than that of the other groups. Taurine contents in the whole body and tissues increased with the increase in dietary taurine level. These results indicate that juvenile Japanese flounder require at least 15 mg/g taurine in the diet, even though a combined mix of fish, krill and squid meal was the main protein source in the experimental diets.  相似文献   

Comparative study on thermal denaturation modes of myosin in walleye pollack and carp myofibrils as affected by salt concentration     

Masayuki?Takahashi  Takeshi?Yamamoto  Sanae?Kato  Kunihiko?KonnoEmail author 《Fisheries Science》2005,71(3):662-671

ABSTRACT:   The effect of salt concentration on the thermal denaturation profile of myosin in walleye pollack and carp myofibrils was compared by studying the subfragment-1 (S-1) and rod denaturation rates upon heating. Species-specific denaturation mode observed at 0.1 M KCl was no longer detected when samples were heated above 0.5 M KCl, where S-1 and rod denaturation rates were identical to each other. As the heating of the chymotryptic digest of myofibril formed practically no rod aggregates, S-1 denaturation in a form of myosin was the rate limiting step for rod aggregate formation. As the aggregate formation by rod was remarkably suppressed by lowering the temperature, the free movement of myosin tail upon heating was suggested to play an important role in the rod aggregate formation in a high salt medium.  相似文献   

Different combinations of protein ingredients in carp diets for reducing phosphorus loading     

Parveen  JAHAN  Takeshi  WATANABE  Shuichi  SATOH  Viswanath  KIRON 《Fisheries Science》2002,68(3):595-602

ABSTRACT: This study was conducted to gather data on the reduction of environmental phosphorus (P) loading through the formulation of carp diets with different combinations of protein ingredients. Five experimental diets were formulated by substituting fishmeal (FM; 10–20%) with alternative protein sources such as meat meal (MM; 5–15%), blood meal (BM; 5–7%), and defatted soybean meal (dSBM; 6–10%). The control diet used was a commercial carp diet selected based on earlier experiments. Each diet was fed to duplicate groups of juvenile carp three times a day, until satiation for 12 weeks. Feed performance was proportional to the increase in dietary FM levels. Phosphorus absorption ranged between 41.6% and 52.0% among the experimental groups and was 42.6% for the control group, but there were no marked differences in nitrogen (N) absorption rates. Phosphorus retention ranged from 31.4% to 35.7% for the test diets, whereas N retention increased proportionally with dietary FM levels and ranged from 34.7% to 41.7%. The P and N retention values of the control diet were 27.6% and 41.2%, respectively. The total P loading (T-P) increased at the higher FM levels (9.1–10.7 kg/t production), whereas lower FM levels produced higher total N loading (T-N, 34.6–43.1 kg/t production), the figures for the control being 13.9 T-P kg/t production and 35.6 T-N kg/t production. These results indicate that the reduction of FM levels to 10–20% by replacing it with MM, BM, and dSBM in carp diets was effective in reducing the loading of P and N.  相似文献   

Gene dropping analysis of founder contributions in a closed Japanese black cattle population   总被引：1，自引：0，他引：1  

Takeshi HONDA  Tetsuro NOMURA  Moriyuki FUKUSHIMA  Fumio MUKAI 《Animal Science Journal》2002,73(2):105-111

Gene dropping simulation was applied to Japanese Black cattle population in Hyogo prefecture, to examine the survivals of alleles originated from founder animals. In the analysis, unique alleles were assigned to founders, and the genotypes of all descendants along the actual pedigree were generated through Monte Carlo simulation following Mendelian segregation rules. By replicating this process 10 000 times, the distribution of frequencies of alleles from each founder was estimated. From the distribution, several quantities useful for the management of genetic diversity, such as the probability of allele extinction and the probability of alleles surviving at a critically low frequency were derived. The materials used were 68 781 animals born in 1955–1998 and their pedigree records traced back to the population in 1937 or before. The expected number of alleles retained in the population drastically decreased during the analyzed period, and reached to 57.9 in the population of 1998, which was only 3.3% of the total number of alleles assigned to founders. Detailed analysis of major founders with relatively high genetic contributions to the current population revealed that alleles from most of the major founders are now at high risk of future extinction. These results strongly suggest that for the management of genetic diversity, the genetic contributions of founders are not fully informative, and emphasize the importance of the detection of live animals having founder alleles with high extinction possibilities.  相似文献   

Differences in the external shape of the pleopods of Palaemon paucidens and Macrobrachium nipponense in terms of swimming ability     

Takeshi  YAMANE  Tomonori  HIRAISHI  Yasuhiro  YAMAGUCHI 《Fisheries Science》2003,69(6):1103-1108

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Effect of Fe, Mn or Al Compounds on Humification of Three Types of Plant Residues during Thermal Incubation     

Socorro Asuncion Bulosan-Atendido  Takeshi Suzuki  Nobuhide Fujitake  Hiroo Otsuka 《Soil Science and Plant Nutrition》2005,51(7):925-933

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Effects of silviculture treatments in a hurricane-damaged forest on carbon storage and emissions in central Hokkaido,Japan   总被引：1，自引：0，他引：1  

Toshiaki Owari  Naoto Kamata  Takeshi Tange  Mikio Kaji  Akio Shimomura 《林业研究》2011,21(1):13-20

Hurricanes cause abrupt carbon reduction in forests, but silviculture treatment can be an effective means of quickly regenerating and restoring hurricane-damaged sites. This study assessed how silviculture treatments affect carbon balance after hurricane damage in central Hokkaido, Japan. We examined carbon storage in trees and underground vegetation as well as carbon emissions from silviculture operations in 25-year-old stands, where scarification and plantation occurred just after hurricane damage. The amount of carbon stored varied according to silviculture treatment. Among three scarification treatments, a scarified depth of 0 cm (understory vegetation removal) led to the largest amount of carbon stored (64.7 t·ha-1 C). Among four plantation treatments, the largest amount of carbon was stored in a Larix hybrid (L. gmelinii var. japonica × L. kaempferi) plantation (80.3 t·ha-1 C). The plantation of Abies sachalinensis was not successful at accumulating carbon (40.5·ha-1 C). The amount of carbon emitted from silviculture operations was 0.05-0.14 t·ha-1 C, and it marginally affected the net carbon balance of the silviculture project. Results indicate that silviculture treatments should beperformed in an appropriate way to effectively recover the ability of carbon sequestration in hurricane-damaged forests.  相似文献   

Soil nitrogen dynamics of forest ecosystems under environmental changes     

Hideaki Shibata  Hiroto Toda  Yoshiyuki Inagaki  Ryunosuke Tateno  Keisuke Koba  Takeshi Tange 《Journal of Forest Research》2011,16(5):331-332

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