Diurnal variation of tryptic activity in larval stage and development of proteolytic enzyme activities of malabar grouper (Epinephelus malabaricus) after hatching     

Aya Fujii  Yuko Kurokawa  Shin''ichiro Kawai  Kenzo Yoseda  Shigeki Dan  Aya Kai  Masaru Tanaka   《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):68-76

Diurnal variation in tryptic activity and developmental changes in proteolytic enzyme activities of malabar grouper larvae (Epinephelus malabaricus) were examined. Five different groups were prepared for the experiment of diurnal variation of tryptic activity in larvae: larvae were fed Thai-type rotifers Brachionus rotundiformis from the time of mouth opening, fed rotifers from 6 h after mouth opening, 12 h, 24 h and not fed rotifers (starved control). The experimental tanks were placed in temperature-controlled baths at 28 °C under 24 h light. Developmental changes in proteolytic activity of trypsin and pepsin-like enzyme were measured from hatching to 57 days after hatching (DAH).

The tryptic activity of all fed groups showed the same pattern, and the diurnal variation of tryptic activity was clearly observed from 3 to 6 DAH. The highest tryptic activities were found at 19:00, and the activities were lowest from 01:00 to 07:00. In contrast, that of non-fed larvae was low compared to the fed groups, however the diurnal variation of tryptic activity was shown same tendency to the fed groups. Interestingly, both groups (fed and non-fed) were exhibited a circadian rhythm under the 24 h light conditions and delaying of first-feeding. Tryptic activity of larvae notably increased from 40 to 45 DAH and markedly decreased at 52 DAH. In contrast to the tryptic activity, that of pepsin-like enzyme clearly increased from 47 to 51 DAH. The results suggest that a functional change of protein digestion occurs from 40 to 50 DAH related with metamorphosis in malabar grouper. These results could contribute to determining appropriate feeding schedules, such as feeding time, frequency and optimal time to change food items, in mass-scale production of the present species.  相似文献   

Observation on the spawning of Sardina and Sardinella off the south Moroccan Atlantic coast (21–26°N)     

O. Ettahiri  Am. Berraho  G. Vidy  M. Ramdani  T. Do chi 《Fisheries Research》2003,60(2-3):207-222

This paper provides information on the early life stages of the Moroccan Atlantic sardine, Sardina pilchardus, and two species of Sardinella: Sardinella aurita and S. maderensis, between Cape Blanc (21°N) and Cape Boujdor (26°N), dealing with the spawning grounds, the nursery areas and the optimal spawning temperature and salinity range.

The spawning areas for Sardina are located North of Dakhla (24°30′–25°30′N) and near Cintra Bay (23°N). The larval development area is described together with seasonal and annual characteristics. The nurseries of Sardina are near Dakhla and to the south between 21 and 22°N but precise locations vary with season. The maximum occurrence of eggs was during winter, and was at temperatures from 16 to 18 °C in winter and between 18 and 18.5 °C in summer.

The main spawning area of Sardinella species is between Cape Blanc and Cintra Bay (21–23°N) with a maximum occurrence of eggs and larvae in July. For Sardinella off the southern region of Morocco, the optimal temperature interval for spawning is between 18 and 21.14 °C. No conclusions can be drawn on the relationship between spawning and water salinity.

The area north of Cintra Bay has a broad, but shallow continental shelf. This topography leads to decreasing dispersion effects and the zone constitutes a favorable area for larval retention and development.  相似文献   

Reproductive behaviour and early development in yellowtail kingfish (Seriola lalandi Valenciennes 1833)     

Damian Moran  Cea K. Smith  Carolyn W. Poortenaar 《Aquaculture (Amsterdam, Netherlands)》2007,262(1):95-104

The spawning behaviour of wild caught brood stock as well as early egg and larval development were studied in yellowtail kingfish (Seriola lalandi). Spawning occurred naturally in the austral spring/summer (November-February) when the seawater temperature was above 17 °C. Courtship behaviour involved one male and female, and consisted of a high-speed pursuit punctuated by stalling, nipping and touching. This lasted for approximately 0.5-1.5 h until, immediately prior to spawning, the male would nip at the female gonoduct, presumably to induce spawning. At this stage, in 50% of spawns, a second male would become involved. The release of gametes involved frenzied circling behaviour near the bottom of the tank and lasted approximately 22 s. Spawning occurred in the early daylight hours at the start of the spawning season, but shifted to around dusk in the latter part. Spawned eggs were positively buoyant, had a high fertilisation rate (> 99%), ranged 1.33-1.50 mm in diameter with a single oil droplet 0.30-0.33 mm diameter, and developed in a similar manner to that described in congenerics. Egg viability within the floating fraction was visually determined to be 74% ± 17% over the entire reproductive season. Indistinct cell margins and asymmetrical cleavage were the most common blastomere deformities observed. Egg and oil droplet volume were found to decrease by 15-20% over the spawning season, though no relationship was found between visually assessed egg viability and date. Egg incubation trials between 16 and 24 °C indicated that temperature accelerated the time to hatch by a Q₁₀ of 5.0. While larvae were found to hatch at a smaller length with a larger yolk sac and oil droplet at warmer incubation temperatures, there was little difference in the maximum larval length reached at the onset of first feeding among the rearing temperatures used. It is proposed that the reason for this was that higher incubation temperatures accelerated the hatching process faster than the rate of tissue deposition. The findings from this study are discussed in terms of the biological significance and implications for the larviculture of this species.  相似文献   

Effect of temperature on hatching success and size of striped trumpeter (Latris lineata) larvae     

D. T. Morehead  P. R. Hart 《Aquaculture (Amsterdam, Netherlands)》2003,220(1-4):595-606

Egg samples were collected from captive striped trumpeter maintained under phase-shifted and simulated ambient photothermal regimes and incubated at 9, 10, 11, 12, 13, 14, 15 or 16 °C. No eggs hatched at 9 °C. Time to hatch decreased from 9.6 to 4.2 days as temperature increased from 10 to 16 °C. Survival to hatch was low at 10 and 11 °C, but similar within the range 12–16 °C. Larval length at hatching was greatest at 14 °C, with no significant difference in yolk volume or muscle depth at vent across the range of temperatures. The results of our study suggest that the optimal temperature for the incubation of striped trumpeter eggs is 14 °C, which is higher than found previously.  相似文献   

Reciprocal hybrids of tench Tinca tinca (L.) × bream Abramis brama (L.), and tench × carp Cyprinus carpio L., and some characteristics of their early development     

Andrzej Mamcarz  Dariusz Kucharczyk  Roman Kujawa 《Aquaculture International》2006,14(1-2):27-33

Reciprocal hybrids between tench Tinca tinca (L.) and carp Cyprinus carpio L., and tench and bream Abramis brama (L.) were produced artificially. The survival of all these hybrids during embryogenesis was quite high. The highest survival rate (over 60%) at the eyed stage was observed for tench and bream hybrids (both sex combinations). The hatching rates of these hybrids were also over 60%. The number of larvae with some abnormalities (i.e. deformed body) was low. In contrast, the hatching rates of tench and carp hybrids were very low (0.2%). From over 1000 fertilized eggs, only three specimens started swimming, and only one specimen survived to juvenile stage. Embryos of hybrids and their parental species differ in morphological features. These differences were also visible in the juveniles. Body parameters of juvenile hybrids produced from three species had intermediate values in comparison to parental fish.  相似文献   

Comparative Study of Malathion Toxicity and General Esterases in Larvae and Adults from a Field Population of Oxya chinensis (Thunberg)(Orthoptera:Acridoidea)     

WU Hai-hua  YANG Mei-ling  GUO Ya-ping  MA En-bo 《中国农业科学(英文版)》2004,3(11)

The susceptibility of Oxya chinensis to malathion was compared in larvae and adults from a field population, collected from Jinyuan outskirt, Shanxi Province. The results showed that Oxya chinensis was more susceptible to malathion in the adult stage than in the larval stage. The LD50 values for malathion susceptibility of Oxya chinensis were 4.94 and 2.44 mg g-1 body weight in the larvae and adults respectively. The results indicated that the larvae were 2.02-fold less susceptible to malathion than the adults. The general esterases and the kinetics were characterized and compared between the two life stages and between females and males. Larval preparations of Oxya chinensis were more active than adult preparations in females and males. The larvae showed 1.18-, 1.49-, and 1.17-fold higher specific activities than the adults in females with α -NA, α -NB and β -NA respectively. In males, the ratios were 1.34-, 1.70-, and 1.06-fold. Female preparations were more active than those of males in the adults. The reverse results were observed in the larvae where male preparations were more active than female preparations. Kinetic studies showed that Km values of general esterases hydrolyzing α -NA, α -NB, and β -NA in the adult stage were 1.36-, 1.32- and 1.39-fold respectively, higher than those in the larval stage in females. In males, the ratios were 1.24-, 2.14-, and 1.20-fold. The esterase from male insects had a higher affinity (lower Km value) to the substrate than those from females. The results also showed that the Vmax values of general esterase hydrolyzing α -NA, α -NB, and β -NA in the two stages were similar. From the results of bioassays and biochemical analyses, it has been inferred that a higher level of resistance to malathion in larvae than in adults would appear to result from differences in the expression of resistance mechanisms in these two life stages. Enhanced esterase activities appeared to play a major role in resistance to malathion in both larvae and adults. From the analysis of inhibition in vitro, the esterases in the two life stages were B-type,and carboxylesterases were predominant enzymes in the composition of the esterases in the two stages.  相似文献   

Mass mortality of native anuran tadpoles in tropical Australia due to the invasive cane toad (Bufo marinus)     

Michael R. Crossland  Marion Anstis  Richard Shine 《Biological conservation》2008,141(9):2387-2394

Specific pathways of the ecological impact of invasive species remain poorly known. Although the spread of toxic cane toads (Bufo marinus) through tropical Australia is widely believed to have caused extensive mortality of native reptiles and mammals, effects of toad ingestion on native anurans have been virtually ignored. Our studies on the Adelaide River floodplain show that the most numerous vertebrate victims of toad invasion are native tadpoles that die when they attempt to consume toad eggs. We documented 11 episodes of mass mortality, totalling >1300 tadpoles of 10 species, in five waterbodies within a single wet-season shortly after the toads invaded. A causal link between toad breeding and tadpole mortality is supported by observations that: (1) in at least 9 of the 11 waterbodies involved, toads bred immediately prior to mortality events; (2) water quality was indistinguishable from that of control ponds, and tadpoles placed in that water remained healthy; (3) dead tadpoles showed no sign of disease; and (4) laboratory trials showed rapid, 100% mortality in native tadpoles exposed to freshly-laid toad eggs. Despite these high mortality rates, toad invasion does not appear to threaten the viability of anuran populations because frogs often breed in ponds not used by toads, and because density-dependent growth and survival within tadpole communities mean that additional mortality may not reduce the total effective recruitment of metamorph frogs from a waterbody.  相似文献   

桔小实蝇幼虫呼吸代谢研究     

刘珍  曾玲 《安徽农业科学》2017,45(22)

[目的]明确桔小实蝇幼虫的呼吸代谢特征。[方法]以重要的水果害虫桔小实蝇幼虫为对象,研究其呼吸代谢特征。[结果]桔小实蝇整个幼虫期总耗氧量达21.61 mL,耗氧量随着幼虫的生长发育而增加。各日龄幼虫的呼吸代谢存在显著差异,而这种差异与它们的生活特性有直接相关性。[结论]研究结果为进一步了解桔小实蝇为害规律和制定检疫处理技术提供了参考。  相似文献   

天幕毛虫核型多角体病毒对天幕毛虫幼虫的致病机理   总被引：1，自引：0，他引：1  

胡春祥  张志强 《东北林业大学学报》2008,36(3):65-67

用天幕毛虫核型多角体病毒(Nucleus polyhedrosis virus,NPV)感染天幕毛虫(Malacosoma neustriatestacea Motschulsky)幼虫,对其致病机理的研究表明:该病毒可以侵染和破坏天幕毛虫的中肠细胞,在中肠组织细胞中均能观察到形成的多角体。幼虫取食核型多角体病毒100 h后,在光学显微镜下可见细胞核内出现多角体形成,细胞核开始增大;取食130 h后,中肠组织细胞间出现缝隙,细胞核内多角体数量增多;取食160 h后,中肠细胞的细胞核进一步增大,个别细胞核增大至整个细胞的1/3以上,与正常天幕毛虫幼虫相比,整个虫体出现软化;取食190 h后,中肠细胞受到严重破坏,细胞结构模糊不清,中肠内食物极少并有许多游离的核型多角体存在;取食220 h后,天幕毛虫幼虫的中肠和其他组织完全受到破坏。  相似文献