32 resultados para 2nd Year
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
It has been demonstrated that growth hormone (GH) transgenic fish often posses a trait for fast growth. Here, we investigated the growth of F-4 'all-fish' GH transgenic carp Cyprinus carpio and their serum GH levels for a year. The results showed that F-4 all-fish GH transgenic carp were significantly larger in body mass (c. two-fold, P < 0 center dot 001) and body length (c. 1 center dot 3 fold, P < 0 center dot 001), compared with the non-transgenic group. The discrepancy of serum GH levels between the transgenic carp group and control group is 54 fold, when the water temperature was 12-34 degrees C. When the water temperature decreased to 3 center dot 5 degrees C in January, the discrepancy was 256 fold. The serum GH level of the transgenic group was relatively constant, while that of control varied greatly based on month and water temperature. The changes of growth rates between the transgenic group and the control group were similar for a year. Taken together, the results indicated that F-4 all-fish GH transgenic carp had not only higher and constant serum GH levels but also a significant fast-growing effect, compared with the control. To our knowledge, this is the first report on a one-year investigation of growth trait and serum growth hormone level in F-4 all-fish GH transgenic carp.
Resumo:
Gastric mills of 362 specimens of two-year-old Chinese mitten crab (Eriocheir sinensis), which contained recognizable food items, from Lake Bao'an, China were examined. The food items were macrophytes, algae, arthropods, oligochaetes, fish, protozoa, rotifers, gastropods, and detritus, and the percent frequencies of occurrence (FO) for these items were 87.3%, 82.0%, 48.2%, 28.2%, 28.7%, 0.3%, 0.6%, 0.3% and 88.7%, respectively. Unidentified animal tissue was often observed and had a FO of 46.1%. In total, FO of plants (macrophytes + algae) was 87.7% and of animals was 89.8%. However, 5.8% of the gastric mills contained only animals, 5.3% had only macrophytes, and 0.3% contained only algae. There was no significant difference (p>0.05) in food habits between male and female crabs. The ratio of cell number of macrophytes to algae was about 156:1.
Resumo:
Population dynamics of Chaoborus flavicans larvae of various instars was studied from November 1986 to December 1987 in a eutrophic, fish-free pond, Japan. First and 2nd instar larvae were observed from late April to late October, indicating a reproductive period of about half a year. C. flavicans overwintered in the 4th instar larvae. In water column samples, total density of all instars was 680-23 680 m(-2), and pupal density 0-2 600 m(-2); larvae of the Ist, 2nd, and 3rd instars showed 5-6 density peaks in 1987, suggesting that 5-6 generations occur during a year (peaks of the 4th instar larvae were not clear, probably due to their longer development than those of younger instars). In sediment samples, no Ist and 2nd instar larvae were found, 3rd instar larvae were found occasionally but density of the 4th instar larvae was 280-18 600 m(-2), and pupal density varied between 0-502 m(-2). Fouth instar larvae accumulated in sediment in the cold season and in the water column in the warm season; high temperature and low oxygen concentration were the most important factors limiting the distribution of larvae in the sediment in summer in the NIES pond. The dry weight of total C. flavicans larvae was 0.08-4.2 g m(-2) in sediment samples and 24-599 mu g l(-1) (0.10-2.40 g m(-2)) in water column samples. Comparisons of maximum densities in the NIES pond in different years and in waters of different trophic status show that density is generally higher in eutrophic than in oligotrophic habitats.
Resumo:
Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-13T14:02:33Z No. of bitstreams: 1 A new year message from Chinese Science Bulletin.pdf: 888462 bytes, checksum: 950ebfe3456fc0d42f8d058a5d2b3979 (MD5)
Resumo:
IEECAS SKLLQG
