Growth in vertebrates is a complex interaction involving the development of cells, tissues and organs. Hormones regulating growth during maturation are involved mainly in the interaction between the somatic axis and t...Growth in vertebrates is a complex interaction involving the development of cells, tissues and organs. Hormones regulating growth during maturation are involved mainly in the interaction between the somatic axis and the reproduction of brain-pituitary axes. Based on the results of hormone and gene transcriptions, the secretion and treatment controlling both the somatic axis and the gonadotropic axis were affected, directly or indirectly, by the environment parameter through hormones that were studied in my laboratory. A model was proposed for sex differentiation and gonadal development correlating to the growth of European eel (Anguilla anguilla). A high growth variation is affected by the environment. At a low density of eels, the gonadotropin-releasing hormone (GnRH) affected the secretion follicle stimulation hormone (FSH) in the pituitary, steroidogenesis and aromatase (CYP19) synthesis, and the 17β-estradiol (E2) from 11-ketotestosterone (Kt-11) causing ovary development. The ovary secretion E2 affecting the ade-nylate cyclase-activating polypeptide (PACAP), growth hormone (GH) and the insulin-like growth factor (IGF) stimulated rapid growth in females. On the other hand, a high density of eels caused the pituitary gland to secrete FSH at a lower level, and CYP19 was not synthesized in the gonads. The secretion of Kt-11 affected differentiation to testis, which inhibits the somatic axis in reducing growth rate.展开更多
Allelic variation in a total of 7 microsatellites was examined between elvers of freshwater eels (Anguilla japonica and Anguilla anguilla). The number of alleles at these loci ranged from 8 to 26. A single test of eac...Allelic variation in a total of 7 microsatellites was examined between elvers of freshwater eels (Anguilla japonica and Anguilla anguilla). The number of alleles at these loci ranged from 8 to 26. A single test of each locus revealed significant deficits of heterozygotes (P<0.01). Significant departure from expectations of Hardy-Weinberg equilibrium (HWE) was found for all loci within four subpopulations of A. japonica, which opposes the panmixia hypothesis of Schmidt. Also exact tests of population differentiation based on allelic fre- quency distribution disagree the hypothesis of random distribution of individuals among populations. Population structure among four populations of A. japonica was revealed with FST value of 0.009 8 (P=0.000 48; 10 000 iteration). Pairwise matrixes of FST and RST showed a significant difference between two distantly related spe- cies—A. japonica and A. anguilla. Divergent time of the two species calculated by Goldstein method is over 2 million years. The results may challenge the Schmidt’s theory about the distribution of freshwater eels.展开更多
Eels can perform both forward and backward undulatory swimming but few studies a re seen on how eels propel themselves backward. A computational study on the uns teady hydrodynamics of the backward swimming in the eel...Eels can perform both forward and backward undulatory swimming but few studies a re seen on how eels propel themselves backward. A computational study on the uns teady hydrodynamics of the backward swimming in the eel anguilla an guilla is car ried out and presented. A two-dimensional geometric model of the European eel b ody in its middle horizontal section is appropriately approximated by a NACA0005 airfoil. Kinematic data of the backward and forward swimming eel used in the co mputational modeling are based on the experimental results of the European eel. Present study provided the different flow field characteristics of three typical cases in the backward swimming, and confirmed the guess of Wu: When the eel swi ms ste adily, the vortex centers of the reversed von Kármán vortex street are aligned approximately. An extensive comparison between the backward and forward swimmin g further reveals that the controllable parameters, such as frequency, amplitude and wavelength of the traveling wave, have a similar influence on the propulsio n performance as in forward swimming. But it is shown that the backward swimming does not be a “reversed” forward swimming one. The backward swimming does sh ow significant discrepancy in the propulsion performance: utilization of a const ant-amplitude wave profile enables larger force generation for maneuverability but with much lower propulsive efficiency instead of the linear-increasing ampl itude wave profile in the forward swimming. The actual swimming modes eels choos e is the best choice associated with their propulsive requirement, as well as th eir physiological and ecological adaptation.展开更多
文摘Growth in vertebrates is a complex interaction involving the development of cells, tissues and organs. Hormones regulating growth during maturation are involved mainly in the interaction between the somatic axis and the reproduction of brain-pituitary axes. Based on the results of hormone and gene transcriptions, the secretion and treatment controlling both the somatic axis and the gonadotropic axis were affected, directly or indirectly, by the environment parameter through hormones that were studied in my laboratory. A model was proposed for sex differentiation and gonadal development correlating to the growth of European eel (Anguilla anguilla). A high growth variation is affected by the environment. At a low density of eels, the gonadotropin-releasing hormone (GnRH) affected the secretion follicle stimulation hormone (FSH) in the pituitary, steroidogenesis and aromatase (CYP19) synthesis, and the 17β-estradiol (E2) from 11-ketotestosterone (Kt-11) causing ovary development. The ovary secretion E2 affecting the ade-nylate cyclase-activating polypeptide (PACAP), growth hormone (GH) and the insulin-like growth factor (IGF) stimulated rapid growth in females. On the other hand, a high density of eels caused the pituitary gland to secrete FSH at a lower level, and CYP19 was not synthesized in the gonads. The secretion of Kt-11 affected differentiation to testis, which inhibits the somatic axis in reducing growth rate.
基金Project supported by "Su Guang" Program of Shanghai EducationCommittee and the Foundation of Shanghai Education Development(02SG22) and the National Key Basic Research Programs of the Ministryof Science and Technology, China (G1999043705 and 2002CB412405)
文摘Allelic variation in a total of 7 microsatellites was examined between elvers of freshwater eels (Anguilla japonica and Anguilla anguilla). The number of alleles at these loci ranged from 8 to 26. A single test of each locus revealed significant deficits of heterozygotes (P<0.01). Significant departure from expectations of Hardy-Weinberg equilibrium (HWE) was found for all loci within four subpopulations of A. japonica, which opposes the panmixia hypothesis of Schmidt. Also exact tests of population differentiation based on allelic fre- quency distribution disagree the hypothesis of random distribution of individuals among populations. Population structure among four populations of A. japonica was revealed with FST value of 0.009 8 (P=0.000 48; 10 000 iteration). Pairwise matrixes of FST and RST showed a significant difference between two distantly related spe- cies—A. japonica and A. anguilla. Divergent time of the two species calculated by Goldstein method is over 2 million years. The results may challenge the Schmidt’s theory about the distribution of freshwater eels.
基金Project supported by the National Natural Science Foundation of China (Grant No :10332040) and the Chinese Acade-my of Sciences Project (Grant No : KJCX-SW-L04) .
文摘Eels can perform both forward and backward undulatory swimming but few studies a re seen on how eels propel themselves backward. A computational study on the uns teady hydrodynamics of the backward swimming in the eel anguilla an guilla is car ried out and presented. A two-dimensional geometric model of the European eel b ody in its middle horizontal section is appropriately approximated by a NACA0005 airfoil. Kinematic data of the backward and forward swimming eel used in the co mputational modeling are based on the experimental results of the European eel. Present study provided the different flow field characteristics of three typical cases in the backward swimming, and confirmed the guess of Wu: When the eel swi ms ste adily, the vortex centers of the reversed von Kármán vortex street are aligned approximately. An extensive comparison between the backward and forward swimmin g further reveals that the controllable parameters, such as frequency, amplitude and wavelength of the traveling wave, have a similar influence on the propulsio n performance as in forward swimming. But it is shown that the backward swimming does not be a “reversed” forward swimming one. The backward swimming does sh ow significant discrepancy in the propulsion performance: utilization of a const ant-amplitude wave profile enables larger force generation for maneuverability but with much lower propulsive efficiency instead of the linear-increasing ampl itude wave profile in the forward swimming. The actual swimming modes eels choos e is the best choice associated with their propulsive requirement, as well as th eir physiological and ecological adaptation.
