共查询到20条相似文献，搜索用时 15 毫秒
1.
Growth hormone transgenic Atlantic salmon Salmo salar reared at 12–13°C were F2 generation derived, using eggs from a transgenic F1 female and fertilized with milt from a non-transgenic male. At the time of tissue sampling the transgenic salmon were growing 1·6 times faster than control salmon. Transgenic salmon tended to have more intestinal folds that were longer than those of control salmon. Consequently, the transgenic salmon had a larger digestive surface area both in the anterior intestine (surface area 1·5 times control) and in the pyloric caeca (surface area 1·2 times control). Most morphological features of the intestine and of the pyloric caeca of transgenic salmon were larger than those of control salmon; in particular, the surface area of the anterior intestine was concordant with the growth rate difference. 相似文献
2.
Light microscopic and scanning electron microscopic studies present strong evidence for a multiductal system conveying digestive enzymes from the exocrine pancreas into the anterior intestine in Atlantic salmon. 相似文献
3.
Juvenile whitefish, Coregonus lavaretus (L.), wet weight 0.04 to 5.2 g, from Lake Constance were kept at 10, 12 and 16° C water temperature, respectively and fed with living zooplankton. The experimental duration lasted 72 to 120 h. Daily rations were defined as the amount of zooplankton remaining subtracted from the amount of zooplankton added after a 24 h interval. The mortality of the zooplankton was determined in parallel experiments without fish. Relative daily ration (zooplankton weight/fish weight) v. fish weight increased up to a fish dry weight of approximately 0.12 g and then decreased steadily. The maximum daily ration was about 270% of fish body wet weight (wet/wet) corresponding to 75% of body dry weight (dry/dry), respectively. In fishes of a dry weight higher than 0.12 g (wet weight 0.65 g) a significant difference in food intake was found between 12 and 16° C. The specific growth rate ranged from nearly 0 up to 33% per day. No correlation was found between daily ration and specific growth rate. 相似文献
4.
Growth hormone transgenic coho salmon Oncorhynchus kisutch fed at the same ration level as non‐transgenic controls (Tc) had the same growth rate as non‐transgenic controls (Nt). In contrast, growth hormone transgenic coho salmon (Tf) fed ad libitum ate about twice as much and had much higher growth rates than the other two groups. The most obvious result was the significantly larger caeca in the Tf group relative to both Nt or pair‐fed Tc. The Tf fish had more caeca that were longer. The results suggested that the effect was indirect and the enlarged caeca required both the GHtransgene and hyperphagia to cause enlarged caecal capacity. A small part of the results, however, also suggested that there was a direct effect of the GHtransgene on some gut tissues, particularly the intestine. 相似文献
5.
K.J. Millidine J.D. Armstrong N.B. Metcalfe 《Proceedings. Biological sciences / The Royal Society》2009,276(1664):2103-2108
Basal or standard metabolic rate (SMR) has been found to exhibit substantial intraspecific variation in a range of taxa, but the consequences of this variation are little understood. Here we explore how SMR is related to the energy cost of processing food, known as apparent specific dynamic action or the heat increment of feeding. Using juvenile Atlantic salmon Salmo salar, we show that fishes with a higher SMR had a higher peak and a greater total energy expenditure when digesting a given size of meal. However, the duration over which their metabolism was elevated after consuming the meal was shorter. The greater energy costs they incur for processing food may be related to their assimilation efficiency. These relationships are likely to have implications for feeding strategies and growth rates, since individuals with a higher SMR have higher routine costs of living but recover more quickly following feeding and so may have a greater potential for processing food. 相似文献
6.
Vytenis Gotceitas David A. Methven Sandy Fraser Joseph A. Brown 《Environmental Biology of Fishes》1999,54(4):413-420
This study examined the effects of body size and food ration on over-winter survival of age-0 Atlantic cod. Cod were divided into two groups based on standard length (large=76.95±1.10 mm SL; small=57.65±1.02 mm SL; mean±1 SE) and wet weight (large=4.02± 0.21 g; small=1.52±0.09 g). Replicate tanks (n=2) of 10 large and 10 small cod were exposed to one of two food rations (0.25% and 1.0% body weight day-1) for the entire experiment (December to June). Tanks were examined daily for mortalities and feeding was adjusted accordingly. The experiment was run under ambient light and seawater conditions. All but large age-0 cod exposed to the low food ration grew over the course of the experiment. The specific growth rate (SGR) of small cod was significantly higher (0.2425% wet weight day-1) than that of the large fish (0.0443% wet weight day-1). Food ration had no significant influence on SGR or over-winter survival. Significantly more of the large age-0 cod survived the winter (58.5% of those originally introduced) compared to the smaller fish (14%). Our results are consistent with those from studies of several other fish species, and are discussed in relation to the ecology of age-0 cod, and their potential use in aquaculture in Newfoundland. 相似文献
7.
8.
Rahman M. Azizur Mak Rohan Ayad Hala Smith Alan Maclean Norman 《Transgenic research》1998,7(5):357-370
Several lines of transgenic G1 and G2 tilapia fish (Oreochromis niloticus) have been produced following egg injection with gene constructs carrying growth hormone coding sequences of fish origin. Using a construct in which an ocean pout antifreeze promoter drives a chinook salmon growth hormone gene, dramatic growth enhancement has been demonstrated, in which the mean weight of the 7 month old G2 transgenic fish is more than three fold that of their non transgenic siblings. Somewhat surprisingly G1 fish transgenic for a construct consisting of a sockeye salmon metallothionein promoter spliced to a sockeye salmon growth hormone gene exhibited no growth enhancement, although salmon transgenic for this construct do show greatly enhanced growth. The growth enhanced transgenic lines were also strongly positive in a radio-immuno assay for the specific hormone in their serum, whereas the non growth enhanced lines were negative. Attempts to induce expression from the metallo thionein promoter by exposing fish to increased levels of zinc were also unsuccessful.Homozygous transgenic fish have been produced from the ocean pout antifreeze/chinook salmon GH construct and preliminary trials suggest that their growth performance is similar to that of the hemizygous transgenics. No abnormalities were apparent in the growth enhanced fish, although minor changes to skull shape and reduced fertility were noted in some fish. There is also preliminary evidence for improved food conversion ratios when growth enhanced transgenic tilapia are compared to their non-transgenic siblings.The long term objective of this study is to produce lines of tilapia which are both growth enhanced and sterile, so offering improved strains of this important food fish for aquaculture. 相似文献
9.
The duration of the ontogenetic development of the eggs up to hatching time was studied under stable water temperatures for a total of 47 families (the offspring of a single pair of spawners) from eight wild populations and one domesticated stock of Norwegian Atlantic salmon. Eggs from each family were incubated at stable water temperatures of 7·3 and 9·4° C. The number of days required to 50% hatching differed significantly between populations for both experimental temperatures together and for each temperature separately. The interpopulation and intrapopulation variation each accounted for about 50% of the overall variation. Significant differences were found for the days required to 50% hatching between eggs of the domestic stock from The Norwegian Salmon Breeding Company and two natural populations and between some of the wild populations. It is concluded that the time required from fertilisation to hatching in Atlantic salmon is a population-specific adaptive trait. 相似文献
10.
转基因鱼工作的开展被用于水产科学基础与应用研究的各个领域。应用方面的一项重要研究就是利用转生长激素基因来提高鱼的增长速度。需要解决两个问题：一是转基因鱼所使用的基因元件;二是外源基因的高整和率与高表达。已有许多报道认为：不同种动物的生长激素不一定相互促进生长。我们通过显微注射,将鲤鱼金属硫蛋白启动子（ｃＭＴ）与大马哈鱼生长激素基因（ｓＧＨ）的融合基因（ｃＭＴｓＧＨ）导入鲤鱼单细胞后期的早期胚胎,构建了全鱼转基因鲤鱼。通过斑点杂交、Ｓｏｕｔｈｅｒｎｂｌｏｔ结合ＰＣＲＳｏｕｔｈｅｒｎｂｌｏｔ,对外源ｓＧＨ的整和进行了精确的检测和分析。实验选取性成熟鲤鱼,收集卵子和精子,湿法受精获得受精卵。经过基因注射,孵化后的鱼苗放入水族箱。待鱼苗平游,提取总ＤＮＡ进行检测。以ＰｓｔＩ酶切质粒ｐｃＭＴｃＧＨ（Ｆｉｇ．４）分离３．４ＫｂｓＧＨ片段,用随机引物标记,作为杂交探针。同时,设计并合成ｓＧＨ基因的ＰＣＲ特异引物。Ｆｉｇ．１的斑点杂交结果与Ｆｉｇ．２的ＰＣＲＳｏｕｔｈｅｒｎ结果相比较（Ｔａｂｌｅ１）,说明斑点杂交存在着高的假阳性。而ＰＣＲＳｏｕｔｈｅｒｎ将ＰＣＲ的快速、方便与Ｓｏｕｔｈｅｒｎ的准确性相结合,排除了Ｐ 相似文献
11.
12.
F. M. El-Shamy 《Hydrobiologia》1978,60(2):113-124
Adult bluegil grew faster in Lake Mendota than in Lake Wingra. Once and two year old fish from both lakes had similar growth patterns and grew at a rate similar to that of fish from other lakes. Small fish from the two lakes (averaging 10 g) had comparable rations in July but larger fish (averaging 50 g) had daily ration of 3% in Lake Mendota compared to 1% for Lake Wingra fish. Mean number of benthic organisms varied from 364 to 80 per m2 in Lake Wingra as opposed to 1560 to 450 organisms per m2 in Lake Mendota. Fish in Lake Wingra fed selectively on Daphnia and Cyclops, which, although small in size, were relatively larger than the other plankton species. Bluegill from Lake Mendota, on the other hand, fed mainly on large macroinvertebrates such as Hyalella and insects. 相似文献
13.
The absolute gut evacuation rate (GER) (g day−1 ) of Harpagifer antarcticus increased with increasing ration mass, fish mass only influenced the absolute GER at a daily ration level of 0·3% wet fish mass (approximately a maintenance ration). The relative GER (% of meal fed day−1 ) was also affected differently by fish and ration mass depending on the relative ration level being fed; at rations of 0·7% wet fish mass or above the relative GER decreased with increasing fish or ration mass (in such a way that the absolute GER remained constant and unaffected by fish mass). At maintenance (0·3% wet fish mass) rations the relative GER was not affected by fish size or ration mass. Thus, there appears to be a ration threshold above which the digestion physiology alters. Mass-specific GER (% g fish−1 day−1 ) decreased with increasing fish mass. Within a set relative ration level (% wet fish mass) an increase in fish mass decreased the mass-specific GER. At a fixed ration mass, an increase in fish mass (i.e. a reduction in the ration expressed as % fish mass) resulted in a decrease in mass-specific GER. Gut evaluation time (GET) decreased and absorption efficiency (A) increased with increasing absolute GER. The effect of ration and fish mass on the absolute and relative GER followed the same pattern irrespective of the diet, however the A and GER (% day−1 and g day−1 ) were higher and the GET shorter when the fish were fed shelled krill rather than amphipods. 相似文献
14.
C. Rhee H. Kim S.A. Emmanuel H.-G. Kim S. Won J. Bae S.C. Bai S.-C. Koh 《Letters in applied microbiology》2020,70(6):431-439
15.
16.
S. Morais† C. R. Rojas&#;Garcia‡ L. E. C. Conceição I. Rønnestad‡ 《Journal of fish biology》2005,67(1):223-238
The digestion, absorption and post absorptive metabolism of a radiolabelled triacylglycerol (TAG; triolein) and a free fatty acid (FFA; oleic acid), delivered by tube feeding, was studied in herring Clupea harengus larvae, using metabolic chambers and video analysis. In general, a large amount of the delivered lipid was evacuated. Most of the evacuation occurred between 2 and 6 h after tube feeding although a group of larvae responded by rapidly evacuating the lipid (>50% before 2 h). The volume of the tube‐fed lipid affected its utilization. A small volume of triolein (9·2 nl, representing c . 6% of gut filling capacity) resulted in a lower proportion of fast evacuating larvae and improved utilization (lower evacuation and higher absorption: body incorporation and catabolism) compared with 50·6 nl ( c . 17% of gut filling capacity). Increases in the volume of tube fed triolein enhanced only marginally label absorption and led to a steep rise in evacuation. At a comparable high volume (50·6 nl), oleic acid, which does not require digestion, was better absorbed and less evacuated than triolein. The video observation of the lipid digestive process revealed a considerable gut contractile activity that appeared effective in processing the tube fed lipid. Also, the gut wall seemed very sensitive to physical pressure. Signs of chemical degradation during lipid digestion were also noted. The metabolic studies, together with video image analysis, suggested that the limiting step for the utilization of high dietary lipid levels may have been the lipid absorption into the enterocytes and transport into the body, rather than lipid digestion. The results support the notion that the rate of lipid digestion and absorption in fishes is slower than that of mammals. 相似文献
17.
The growth rates of naturally sympatric juvenile pink Oncorhynchus gorbuscha and sockeye Oncorhynchus nerka salmon were compared in a common lacustrine environment in south‐west Alsaka, an unusual opportunity given the normal disparity in freshwater residence time of these two species. Fork length ( L F ) frequency distributions of juvenile pink salmon caught in the lake during the summer in 1991 and 1999–2003 indicated a growth rate of 0·54 mm day−1 , 54% greater than the estimated growth rate of juvenile sockeye salmon sampled from 1958 to 2003 (0·35 mm day−1 ). Examination of daily growth rings on otoliths indicated that pink salmon in Lake Aleknagik grew an average of 1·34 mm day−1 in 2003 but sockeye salmon grew only 0·63 mm day−1 (average specific growth rates were 3·0 and 1·8% day−1 , respectively). Pink salmon increased from c . 32 mm L F and 0·2 g at emergence to 78 mm L F and 3·0 g within 3–4 weeks. After experiencing these rapid growth rates, the pink salmon appeared to leave the lake by late July in most years. The diets of pink and sockeye salmon in the littoral zone of the lake were very similar; >80% of the stomach contents consisted of adult and pupal insects and the remainder was zooplankton. This high degree of diet overlap suggested that the observed differences in growth rate were not attributable to variation in prey composition. 相似文献
18.
Intestinal microbiota composition in fishes is influenced by host ecology and environment 总被引：2，自引：0，他引：2
The digestive tracts of vertebrates are colonized by complex assemblages of micro-organisms, collectively called the gut microbiota. Recent studies have revealed important contributions of gut microbiota to vertebrate health and disease, stimulating intense interest in understanding how gut microbial communities are assembled and how they impact host fitness (Sekirov et al. 2010). Although all vertebrates harbour a gut microbiota, current information on microbiota composition and function has been derived primarily from mammals. Comparisons of different mammalian species have revealed intriguing associations between gut microbiota composition and host diet, anatomy and phylogeny (Ley et al. 2008b). However, mammals constitute <10% of all vertebrate species, and it remains unclear whether similar associations exist in more diverse and ancient vertebrate lineages such as fish. In this issue, Sullam et al. (2012) make an important contribution toward identifying factors determining gut microbiota composition in fishes. The authors conducted a detailed meta-analysis of 25 bacterial 16S rRNA gene sequence libraries derived from the intestines of different fish species. To provide a broader context for their analysis, they compared these data sets to a large collection of 16S rRNA gene sequence data sets from diverse free-living and host-associated bacterial communities. Their results suggest that variation in gut microbiota composition in fishes is strongly correlated with species habitat salinity, trophic level and possibly taxonomy. Comparison of data sets from fish intestines and other environments revealed that fish gut microbiota compositions are often similar to those of other animals and contain relatively few free-living environmental bacteria. These results suggest that the gut microbiota composition of fishes is not a simple reflection of the micro-organisms in their local habitat but may result from host-specific selective pressures within the gut (Bevins & Salzman 2011). 相似文献
19.
D. B. Sigourney †‡ B. H. Letcher † M. Obedzinski †§ R. A. Cunjak &#; 《Journal of fish biology》2008,72(10):2435-2455
A combination of a dynamic energy budget (DEB) model, field data on Atlantic salmon Salmo salar and brown trout Salmo trutta and laboratory data on Atlantic salmon was used to assess the underlying assumptions of three different metrics of growth including specific growth rate (G), standardized mass‐specific growth rate (GS) and absolute growth rate in length (GL) in salmonids. Close agreement was found between predictions of the DEB model and the assumptions of linear growth in length and parabolic growth in mass. Field data comparing spring growth rates of age 1+ year and 2+ year Atlantic salmon demonstrated that in all years the larger age 2+ year fish exhibited a significantly lower G, but differences in growth in terms of GS and GL depended on the year examined. For brown trout, larger age 2+ year fish also consistently exhibited slower growth rates in terms of G but grew at similar rates as age 1+ year fish in terms of GS and GL. Laboratory results revealed that during the age 0+ year (autumn) the divergence in growth between future Atlantic salmon smolts and non‐smolts was similar in terms of all three metrics with smolts displaying higher growth than non‐smolts, however, both GS and GL indicated that smolts maintain relatively fast growth into the late autumn where G suggested that both smolts and non‐smolts exhibit a sharp decrease in growth from October to November. During the spring, patterns of growth in length were significantly decoupled from patterns in growth in mass. Smolts maintained relatively fast growth though April in length but not in mass. These results suggest GS can be a useful alternative to G as a size‐independent measure of growth rate in immature salmonids. In addition, during certain growth stanzas, GS may be highly correlated with GL. The decoupling of growth in mass from growth in length over ontogeny, however, may necessitate a combination of metrics to adequately describe variation in growth depending on ontogenetic stage particularly if life histories differ. 相似文献
