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151.
鳗鲡仔,幼鱼年龄生长的研究 总被引:3,自引:0,他引:3
辽东半岛黄海北部沿岸河口4—6月溯河的白仔鳗,全长53.5—64.5毫米,平均58.83毫米,体长频率高峰位于57.1—59.0 毫米体长组,其体长体重呈直线相关。白仔鳗与幼鳗群体的体长、体重则是指数相关,其方程为W=1.136×10~(-7) L~(3.3871)。12尾白仔鳗耳石平均日轮数为146.3,据此对其产卵期进行了推测,观察证实,在不同生态条件下生活过的幼鳗耳石的环纹有过渡带存在。 相似文献
152.
Impacts of diet on hindgut microbiota and short‐chain fatty acids in grass carp (Ctenopharyngodon idellus)
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Yao Tong Hao Shan Gong Wu Ivan Jakovlić Hong Zou Wen Xiang Li Gui Tang Wang 《Aquaculture Research》2017,48(11):5595-5605
Diet is known to influence intestinal microbiota in fish, but the specifics of these impacts are still poorly understood. Different protein/fibre ratio diets may result in differing structures and activities of gut microbiota. We examined the hindgut microbiome of grass carp (Ctenopharyngodon idellus) fed three different diets: fish meal (FM, high protein – low fibre), Sudan grass (SG, high fibre – low protein) and compound feed (CF, intermediate). Microbial profiles of fish fed on FM were significantly different from profiles of fish fed CF and SG (F = 18.85, p < .01). Cetobacterium, known to be positively associated with protein digestion, was the dominant microbial group in FM samples (approximately 75.7%), while Lachnospiraceae and Erysipelotrichaceae, thought to be involved in fermentation of plant polysaccharides, were dominant in CF and SG samples (46.8% and 42.9% respectively). Network analyses indicated that the abundance of Lachnospiraceae and Erysipelotrichaceae was in a significantly positive correlation (r = .895, p = .001). Short‐chain fatty acid (SCFA) levels may indicate that the digestibility of diet by microbiota in the grass carp gut decreased from FM to SG (FM>CF>SG). Overall low SCFA levels indicate that hindgut fermentation probably provides a low proportion of energy requirements in grass carp. 相似文献
153.
日粮水平和饵料种类对真鲷能量收支的影响 总被引:7,自引:0,他引:7
以玉筋鱼为铒料生物,采用室内流水模拟实验法研究了摄食水平和饵料种类对真鲷能量收支各组分和能量收支分配模式的影响。结果表明,真鲷的生长量、总代谢量、排泄量及生态转换效率均随日粮水平升高呈减速增长趋势,二者之间的定量关系均可用对数曲线加以定量描述;不同生物饵料能造成真鲷摄食、生长、排泄和总代谢水平的显著差异,但却不能改变以比能值为单位的生态转换效率。依据各收支过程的量化结果,可得到真鲷的能量分配模式。 相似文献
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157.
Effect of dietary phosphorus levels on growth and body composition of crucian carp,Carassius auratus under indoor and outdoor experiments
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Indoor and outdoor experiments were carried out simultaneously to evaluate the effects of dietary phosphorus levels on growth performance and body composition of crucian carp. Monocalcium was used to formulate extruded feed containing available phosphorus (AP) of 1.5 (D1), 4.7 (D2), 6.3 (D3) and 9.0 (D4) g kg?1. Twelve 500‐L recirculating tanks were assigned to four triplicate groups with each tank stocked with 15 juveniles (39.88 ± 0.14 g) for indoor experiment. Twelve polyethylene enclosures were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). After 8 weeks of feeding, survival ranged from 96% to 100%. Weight gain, special growth rate, protein efficiency ratio and feed conversion rate did not show significant differences among dietary treatments in both experiments. Fish cultured in the enclosures grew better, although D1 and D2 treatments did not reach significant level. Crude protein and phosphorus content of the fish were not significantly affected by dietary phosphorus level. Moisture, crude lipid, crude ash and vertebrae phosphorus were significantly affected by different phosphorus levels. Based on vertebrae phosphorus, crucian carp cultured in the tanks and in the enclosures showed phosphorus deficiency under 4.7 g kg?1 and 6.3 g kg?1 AP, respectively. 相似文献
158.
Qiufen Li Y. Zhang D. Juck N. Fortin Charles W. Greer Qisheng Tang 《Aquaculture International》2010,18(6):977-990
In this study, we investigated the bacterial communities in the shrimp and sea cucumber culture environment, including shrimp ponds (SP), sea cucumber ponds (SCP), mixed-culture ponds (MCP) and the effluent channel (EC) in Qingdao, China. Bacteria cultivation showed that the counts of heterotrophic, nitrate-reducing and sulfate-reducing bacteria in the sediment of SP were higher than that in the sediment of SCP and MCP, varying between 8.7 × 104 and 1.86 × 106, 2.1 × 104 and 1.1 × 105, and 9.3 × 101 and 1.1 × 104 CFU g?1, respectively. In contrast, the counts of ammonium-oxidizing and nitrifying bacteria in the sediment of SP was lower than that in the sediment of SCP and MCP. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene and dendrogram analyses showed that bacterial diversity in the mixed-culture environment was higher than that in the monocultures. The similarity of bacterial community between EC and SCP or MCP was higher than that between EC and SP. These results indicated that sea cucumber culture played a significant role in influencing the environmental bacterial communities that were composed mainly of Flavobacteriaceae (64.3%), Bacteriodetes (21%) and delta proteobacteria (14.7%), including the genera of Croceimarina, Lutibacter, Psychroserpens and so on. The results explained the benefit of sea cucumber culture in shrimp ponds at the level of microbial ecology. 相似文献
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AIM: To investigate the mechanisms of transdifferentiation of renal tubular epithelial cells by the observation of serial activation of embryonic pax2 and WT1 genes in chronic renal failure model of 5/6 nephrectomized injury. METHODS: Embryo of mice, cultured renal tubule cells and chronic renal failure rat model of 5/6 nephrectomized injury were established. The expressions of paired Box gene (pax2) and Willm’s tumor gene (WT1), as well as α-smooth muscle actin (α-SMA), a phenotype of mesenchymal cells, were detected by RT-PCR and immunohistochemistry techniques. RESULTS: (1) Expressions of pax2 and WT1 mRNA began at 11.5 d and 14 d of embryo and increased gradually, and expression in trace quantity at 2 weeks after birth. Immunohistochemistry analysis revealed that WT1 only expressed in the glomerular podocytes and expressions of pax2 and WT1 in adult renal tubular cells were negative. (2) Deno-expression of pax2 and WT1 in some tubular cells appeared at week 2 and peaked at week 4 in 5/6 nephrectomized rats, both showing a same trend of expression. However, pax2 showed another peak at week 10 afterwards. (3) Re-expressions of pax2 and WT1 in TEC at 0.5 and 24 h after treated with IL-1α (10 μg/L) or AngII (10-9 mol/L) were observed respectively, followed by upregulation of α-SMA expression, and mesenchymal cells characters were shown. The effects were inhibited by Ang II receptor 2 antagonist and WT1 antibody, respectively. CONCLUSION: Adult renal tubule cells acquire re-activation of embryonic pax2 and WT1 genes and phenotypes of mesenchymes when challenge with certain injuries. Deno-expression of pax2 and WT1 genes closely relates with high concentration of bioactive facors, such as AngII and IL-1, which are involved in the mechanisms of renal tubule cells transdifferentiation. 相似文献