A feeding trial was conducted in a recirculating water system to investigatethe effects of dietary protein levels on growth, feed utilization, hepatosomatic index and liverlipid deposition of juvenile red snapper, Lut...A feeding trial was conducted in a recirculating water system to investigatethe effects of dietary protein levels on growth, feed utilization, hepatosomatic index and liverlipid deposition of juvenile red snapper, Lutjanus argentimaculatus (average initial wet weight 8.0± 0.39 g and total length 3.14 ± 0.3 cm). In the experiment, six fishmeal-based diets wereformulated to contain various protein levels (20% to 45% in 5% increments), with dietary energyranging from 2210.7kJ100g to 2250.2 kJ 100g dry matter. The protein to energy ratios of diets rangedfrom 8.58 mg protein kJ^(-1) to 20.03 mg protein kJ^(-1). Diets were fed for 90 d to triplicategroups of fish stocked in 0.128 m^3 seawater tanks, 25 individuals each. The daily ration of 2% wetbody weight was offered to the fish thrice a day. The fish at the end of the study had more thanten-fold (77.0 g) increase in weight compared to the initial (8.0 g). Fish fed diets of 40% and 45%protein produced significantly (P【0.05) higher weight gain of 77.2 g and 76.5 g, and specific growthrate (SGR) of 2.65% and 2.62% than those of 67.0 g and 68.3 g, and 2.49% and 2.51% of the otherdiets. The broken-line regression of SGR against dietary protein level yielded an optimum dietaryprotein requirement of 42.6% (Y = - 1.6295 + 0.1114 X^2, P【0.05). Survival remained 100% amonggroups. Feed conversion ratio decreased from 0.45 for fish fed 20% dietary protein to 0.35 for fishfed 45% dietary protein. Nitrogen intake increased with an increase in dietary protein, which inturn resulted in an increase in nitrogen gain of fish whole body. Fish fed 40% and 45% protein dietsshowed higher (P【0.05) nitrogen gain (0.27g and 0.26g) than those (0.23g and 025g) fed all otherdiets. Gross energy intake (GEI) in fish fed 45% protein was lower (600.67kJ) than that (607.97 kJ)of 40% protein diet, though the differences were not statistically significant (P】0.05); GEI rangingfrom 677.31 kJ to 663.20 kJ at remaining four diets (20% to 35% protein) did not appear to differsignificantly (P】0.05). The highest energy gain of 518.33 kJ was obtained with fish fed 40% protein,resulting in the highest energy retention efficiency of 85.26%. The hepatosomatic index of fish feddiets of 20%, 25%, 30% and 35% protein were significantly (P【0.05) higher (2.09% to 2.57%) thanthose (1.44% and 1.41%) of fish fed diets containing 40% and 45% protein. Liver lipid contentsdecreased from 8.72% to 7.0% in fish fed dietary protein of 20% to 45% in 5% increments. Resultssuggest that the diet containing 40% to 42.6% protein with a P/E ratio of 17.6 mg protein kJ^(-1) isrequired for good growth of L. argentimaculatus weighing between 8.0 g and 85.2 g under the cultureconditions of the present study.展开更多
The countable characters of Qingdao, Zhejiang, Liaoning and Japanese Ayu arecompared. There are no substantial different characters among the former three Ayu, so thecomprehensive values of them are taken as represent...The countable characters of Qingdao, Zhejiang, Liaoning and Japanese Ayu arecompared. There are no substantial different characters among the former three Ayu, so thecomprehensive values of them are taken as representative of Chinese Ayu, which is in turn comparedwith Japanese Ayu ( Plecoglossus altivelis altivelis and Plecoglossus altivelis ryukyuensis). By thecoefficient of difference test, 3 and 4 characters are found to be beyond the subspecies levelbetween Chinese Ayu and nominate subspecies (Plecoglossus altivelis altivelis) and between ChineseAyu (Plecoglossus altivelis chinensis) and Ryukyus subspecies (Plecoglossus altivelis ryukyuensis),respectively, which shows that they belong to different subspecies. The China mainland Ayu is a newsubspecies, Plecoglossus altivelis chinensis Wu and Shan, the establishment of which and its formingcauses are discussed.展开更多
Diversity of bacteria was studied in deep-sea sediments from the Shikoku Basin in the Northwest Pacific Ocean by PCR, RFLP and sequence analysis of 16S rDNA and comparing with Genbank database. Based on the RFLP profi...Diversity of bacteria was studied in deep-sea sediments from the Shikoku Basin in the Northwest Pacific Ocean by PCR, RFLP and sequence analysis of 16S rDNA and comparing with Genbank database. Based on the RFLP profile generated, 77 clones from the 16S rDNA library were divided into 27 types. Phylogenetic analysis showed that the 27 independent clones fell into four groups: Proteobac-teria (62.96%), Chloroflexi (14.81%), Planctomycetes (14.81%) and Acidobacteria (7.41%). Among all sequenced clones, 6 were related to the sulfur or sulfate metabolism bacteria and the results also demonstrated that some bacteria in deep-sea sediments had relation to matter-energy circulation.展开更多
Complementary DNA library of a dinoflagellate Pyrocystis lunula was constructed for the purpose of expression sequence tags analysis. The RNA isolated from this alga was about 20 μg g -1 net cells, and the band inten...Complementary DNA library of a dinoflagellate Pyrocystis lunula was constructed for the purpose of expression sequence tags analysis. The RNA isolated from this alga was about 20 μg g -1 net cells, and the band intensity ratio of 28 S/ 18 S in electrophoresis pattern was nearly 1 to 1. Different cDNA/vector molar ratios were exploited in the ligating reaction to be optimized. The clones produced by cDNA/vector molar ratio of 3.75 to 1 were desirable, most of whose inserts were longer than 300 bp. The recombinants insert length of the unfractionation cDNA library was largely shorter than 500 bp. However, in the fractionation library made from high molecule weight cDNA parts, over seventy percent of the recombinants contained inserts longer than 1 kb, some of which were even longer than 3 kb. Operating concerns were discussed at the end.展开更多
Juveniles of Oreochromis mossambicus with initial wet weights of 0.0382±0.0859 g and initial total lengths of 0.735 ±1.425 cm were tested for their salinity tolerance. The juveniles were subjected to five sa...Juveniles of Oreochromis mossambicus with initial wet weights of 0.0382±0.0859 g and initial total lengths of 0.735 ±1.425 cm were tested for their salinity tolerance. The juveniles were subjected to five salinity levels for a period of seventy five days. These salinity levels correspond to the salinities found along the creek and in estuarine regions. Each set of experiments was conducted at a fifteen day intervals. The weight, length and survival rate were calculated. No mortality was observed at salinity levels 0, 5, 10 and 15, while the juveniles faced slight mortality at 20 in the same environmental conditions, including the diet. There was no significant difference in specific growth rate at all salinity levels. The juveniles of O. mossambicus could survive up to 20 salinity. These results suggest that this species can grow and be exploited commercially in brackish waters, rivers and estuarine regions.展开更多
文摘A feeding trial was conducted in a recirculating water system to investigatethe effects of dietary protein levels on growth, feed utilization, hepatosomatic index and liverlipid deposition of juvenile red snapper, Lutjanus argentimaculatus (average initial wet weight 8.0± 0.39 g and total length 3.14 ± 0.3 cm). In the experiment, six fishmeal-based diets wereformulated to contain various protein levels (20% to 45% in 5% increments), with dietary energyranging from 2210.7kJ100g to 2250.2 kJ 100g dry matter. The protein to energy ratios of diets rangedfrom 8.58 mg protein kJ^(-1) to 20.03 mg protein kJ^(-1). Diets were fed for 90 d to triplicategroups of fish stocked in 0.128 m^3 seawater tanks, 25 individuals each. The daily ration of 2% wetbody weight was offered to the fish thrice a day. The fish at the end of the study had more thanten-fold (77.0 g) increase in weight compared to the initial (8.0 g). Fish fed diets of 40% and 45%protein produced significantly (P【0.05) higher weight gain of 77.2 g and 76.5 g, and specific growthrate (SGR) of 2.65% and 2.62% than those of 67.0 g and 68.3 g, and 2.49% and 2.51% of the otherdiets. The broken-line regression of SGR against dietary protein level yielded an optimum dietaryprotein requirement of 42.6% (Y = - 1.6295 + 0.1114 X^2, P【0.05). Survival remained 100% amonggroups. Feed conversion ratio decreased from 0.45 for fish fed 20% dietary protein to 0.35 for fishfed 45% dietary protein. Nitrogen intake increased with an increase in dietary protein, which inturn resulted in an increase in nitrogen gain of fish whole body. Fish fed 40% and 45% protein dietsshowed higher (P【0.05) nitrogen gain (0.27g and 0.26g) than those (0.23g and 025g) fed all otherdiets. Gross energy intake (GEI) in fish fed 45% protein was lower (600.67kJ) than that (607.97 kJ)of 40% protein diet, though the differences were not statistically significant (P】0.05); GEI rangingfrom 677.31 kJ to 663.20 kJ at remaining four diets (20% to 35% protein) did not appear to differsignificantly (P】0.05). The highest energy gain of 518.33 kJ was obtained with fish fed 40% protein,resulting in the highest energy retention efficiency of 85.26%. The hepatosomatic index of fish feddiets of 20%, 25%, 30% and 35% protein were significantly (P【0.05) higher (2.09% to 2.57%) thanthose (1.44% and 1.41%) of fish fed diets containing 40% and 45% protein. Liver lipid contentsdecreased from 8.72% to 7.0% in fish fed dietary protein of 20% to 45% in 5% increments. Resultssuggest that the diet containing 40% to 42.6% protein with a P/E ratio of 17.6 mg protein kJ^(-1) isrequired for good growth of L. argentimaculatus weighing between 8.0 g and 85.2 g under the cultureconditions of the present study.
文摘The countable characters of Qingdao, Zhejiang, Liaoning and Japanese Ayu arecompared. There are no substantial different characters among the former three Ayu, so thecomprehensive values of them are taken as representative of Chinese Ayu, which is in turn comparedwith Japanese Ayu ( Plecoglossus altivelis altivelis and Plecoglossus altivelis ryukyuensis). By thecoefficient of difference test, 3 and 4 characters are found to be beyond the subspecies levelbetween Chinese Ayu and nominate subspecies (Plecoglossus altivelis altivelis) and between ChineseAyu (Plecoglossus altivelis chinensis) and Ryukyus subspecies (Plecoglossus altivelis ryukyuensis),respectively, which shows that they belong to different subspecies. The China mainland Ayu is a newsubspecies, Plecoglossus altivelis chinensis Wu and Shan, the establishment of which and its formingcauses are discussed.
文摘Diversity of bacteria was studied in deep-sea sediments from the Shikoku Basin in the Northwest Pacific Ocean by PCR, RFLP and sequence analysis of 16S rDNA and comparing with Genbank database. Based on the RFLP profile generated, 77 clones from the 16S rDNA library were divided into 27 types. Phylogenetic analysis showed that the 27 independent clones fell into four groups: Proteobac-teria (62.96%), Chloroflexi (14.81%), Planctomycetes (14.81%) and Acidobacteria (7.41%). Among all sequenced clones, 6 were related to the sulfur or sulfate metabolism bacteria and the results also demonstrated that some bacteria in deep-sea sediments had relation to matter-energy circulation.
文摘Complementary DNA library of a dinoflagellate Pyrocystis lunula was constructed for the purpose of expression sequence tags analysis. The RNA isolated from this alga was about 20 μg g -1 net cells, and the band intensity ratio of 28 S/ 18 S in electrophoresis pattern was nearly 1 to 1. Different cDNA/vector molar ratios were exploited in the ligating reaction to be optimized. The clones produced by cDNA/vector molar ratio of 3.75 to 1 were desirable, most of whose inserts were longer than 300 bp. The recombinants insert length of the unfractionation cDNA library was largely shorter than 500 bp. However, in the fractionation library made from high molecule weight cDNA parts, over seventy percent of the recombinants contained inserts longer than 1 kb, some of which were even longer than 3 kb. Operating concerns were discussed at the end.
文摘Juveniles of Oreochromis mossambicus with initial wet weights of 0.0382±0.0859 g and initial total lengths of 0.735 ±1.425 cm were tested for their salinity tolerance. The juveniles were subjected to five salinity levels for a period of seventy five days. These salinity levels correspond to the salinities found along the creek and in estuarine regions. Each set of experiments was conducted at a fifteen day intervals. The weight, length and survival rate were calculated. No mortality was observed at salinity levels 0, 5, 10 and 15, while the juveniles faced slight mortality at 20 in the same environmental conditions, including the diet. There was no significant difference in specific growth rate at all salinity levels. The juveniles of O. mossambicus could survive up to 20 salinity. These results suggest that this species can grow and be exploited commercially in brackish waters, rivers and estuarine regions.
