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1.
Fish embryo cryopreservation has not been achieved. Different methods and alternative cryoprotective agents (CPAs) should be explored in order to succeed in this purpose. Antifreeze proteins (AFPs) are naturally expressed in sub-arctic fish species, and they inhibit the growth of ice crystals as well as recrystallization during thawing. Therefore, their introduction into embryos can be highly beneficial for vitrification purposes. In this study, AFP type III was introduced into turbot embryos, by microinjection into the yolk sac and the perivitelline space at F stage (tail bud).Toxicity and distribution of protein in microinjected embryos were established before testing the protein effect on embryo cryopreservation. AFP-FITC distribution within the embryo was analyzed by confocal microscopy at 5 min and 24 h after microinjection in F stage embryos. To test the sensitivity of microinjected embryos to CPAs, embryos were subjected to a protocol for the incorporation of a vitrifying solution that was specially designed for turbot embryos. Hatching rates after CPA incorporation were determined. Results indicate that embryos at late developmental stages are more resilient to microinjection, with embryo survival rates between 60 and 82%. Confocal microscopic images demonstrated that the protein was homogeneously distributed within the microinjected embryo compartment, but did not enter any other compartment. On the other hand, microinjected embryos successfully surmounted their incubation in the CPAs. This study explores new alternatives for cryopreservation suggesting the use of natural cryoprotectants (AFPs) in the protection of intra-embryo compartments, which are usually unprotected with the conventional cryopreservation protocols for fish embryos.  相似文献   

2.
The objective of our work was to describe a low toxicity cryoprotectant solution that allowed vitreous solid formation. Embryos of Prochilodus lineatus were submitted to sensitivity evaluations of six internal cryoprotectants (dimethyl sulphoxide – Me2SO, dimethyl acetamide – DMA, dimethyl formamide – DMF, methanol – MET, glycerol – GLY and 1,2‐propanediol – PROP) at concentrations of 1–6 M; and two external cryoprotectants (sucrose – SUC and glucose – GLU) at concentrations of 0.1–1 M for 20 min. The capacity of the cryoprotectant solutions to exchange heat with the medium and to form glassy solids was evaluated by immersing 10 μl of cryoprotectant in liquid nitrogen. The PROP had a high survival rate at all concentrations evaluated, and was the only substance that allowed a vitreous solid formation. Thus, it is concluded that the PROP‐6 M was the most adequate solution for embryonic vitrification processes, because heat exchange between the system (PROP 6 M/embryos/liquid nitrogen) was faster than for other cryoprotectants and combinations thereof; has low toxicity, promote high rates of dehydration in short periods, and reach the vitreous state, being a good candidate to be used in the tests of embryonic vitrification.  相似文献   

3.
The purpose of the present study was to investigate the toxicity of cryoprotectants on the hatching rate of rainbow trout (Oncorhynchus mykiss) embryos. Epiboly and first eye pigmentation stage embryos were immersed in six permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), propylene glycol (PG), ethylene glycol (EG), and acetamide (Ac), in concentrations of 1–5 M for 5 or 10 min and two non-permeable cryoprotectants, sucrose (Suc) (10%, 15%, 20%) and polyvinyl pyrrolidone (PVP) (5%, 10%, 15%) for 5 min. The embryos were then washed and incubated until hatching occurred. The toxicity of the cryoprotectant was assessed by the hatching rate. The results illustrated that permeable cryoprotectant toxicity for rainbow trout embryos increased in the order of PG < DMSO < MeOH < Gly < EG < Ac. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. There were no significant decreases in hatching rate of embryos treated with sucrose and PVP with the increase of concentration; sucrose had higher hatching rates than PVP. Rainbow trout embryos at first eye pigmentation stage exhibited greater tolerance to cryoprotectants than embryos at epiboly stage.  相似文献   

4.

As a study of cryoprotectant toxicity is an essential prerequisite for the development of a cryopreservation protocol, this study focuses on determining the toxicity of four permeable cryoprotectants: dimethyl sulfoxide (DMSO), propylene glycol (PG), methanol (MeOH), and acetamide (Ac). In cryoprotectant toxicity experiments, striped gourami (Trichogaster fasciata) embryos at three different developmental stages (multi cell, 100% epiboly, and proliferation of somites) were exposed to cryoprotectant solutions with concentrations from 1 to 4 M for a period of 5 and 15 min. Following these treatments, the embryos were incubated until the evaluation of hatching rate. Embryos were tolerant to low concentrations of all cryoprotectants tested in the range of 1 to 2 M for all developmental stages. Early stage embryos were more vulnerable to high concentration (3 and 4 M) than late stage embryos. Results also showed that as concentration and duration of exposure increased, the hatching rate significantly decrease (P < 0.05). On a molar-equivalent basis, DMSO appeared to be less toxic to PG, MeOH, and Ac in general. Exposure to cryoprotectants revealed a stage-dependent sensitivity. Toxicity increased in the order of MeOH < DMSO < PG < Ac in multi cell stage and DMSO < MeOH < PG < Ac in 100% epiboly and proliferation of somites stages. The proliferation of somites stage embryos was less sensitive to exposure to cryoprotectants than multi cell and 100% epiboly stages. These findings could be important for designing cryopreservation protocols for this demanding ornamental species.

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5.
Vitrification could provide a promising tool for the cryopreservation of fish embryos. In order to achieve successful cryopreservation, several parameters should be taken into account in the design of a vitrification protocol. In the present study some relevant factors were investigated (permeable and non-permeable cryoprotectant toxicity, toxicity of vitrificant solutions, adequate container for embryo loading and temperature of thawing) using two gilthead seabream embryonic development stages (tail bud and tail-bud-free). Permeabilized embryos were incubated in dimethyl sulfoxide (DMSO), methanol (MeOH), ethylene glycol (EG) and 1,2-propanediol (PROH) in concentrations ranging from 0.5 to 6 M for 10 and 30 min and in 5%, 10% and 15% polyvinyl pyrrolidone (PVP), 10%, 15% and 20% sucrose or 0.1%, 1% and 2% X1000® for 2 min. After treatment, embryos were washed and incubated in seawater until hatched. The toxicity of permeable cryoprotectants increased with concentration and exposure time. EG was best tolerated by the embryos. Exposure to non-permeable cryoprotectants did not affect the hatching rate except at F stage. Six vitrificant solutions (DMSO—V1, V2 and V3 and EG—V1, V2 and V3) were tested using a stepwise incorporation protocol. The DMSO-based solutions contained 5 M DMSO + 2 M MeOH + 1 M EG plus 5% PVP, 10% sucrose or 2% X1000® and the EG-based solutions contained 5 M EG + 2 M MeOH + 1 M DMSO plus 5% PVP or 10% sucrose. Before loading the embryos into 0.5 ml straws or 1 ml macrotubes, toxicity tests were effected with these solutions. Our results demonstrated that DMSO-based solutions were better tolerated by seabream embryos than EG-based solutions. After thawing (water bath, 0 or 25 °C), embryos were evaluated by stereoscopic microscopy and the percentage of embryos with intact morphology was registered. The highest percentage of embryos with intact morphology (28%) was observed in samples frozen in macrotubes and thawed at 25 °C. Several malformations associated with ice crystal formation inside the embryos were detected. None of these embryos achieved hatching. Our results suggest that the absence of a proper incorporation of cryoprotectants prior to vitrification is the main problem that must be overcome. This procedure should be optimized in order to avoid ice crystal formation inside embryo compartments.  相似文献   

6.
Cryoprotectant is the crucial factor in the cryopreservation process. In general, there are two types of cryoprotectant, permeating and non‐permeating cryoprotectants. Dimethyl sulfoxide (DMSO) and egg yolk are common permeating and non‐permeating cryoprotectants respectively. Hence, the objective of the present study was to determine the best proportion of DMSO and egg yolk for the cryopreservation of Rasbora tawarensis sperm. A completely randomized experimental design was used in this study which involves two types of cryoprotectant and their combination at different concentrations, namely 5% DMSO, 5% egg yolk, 5% DMSO + 5% egg yolk and 2.5% DMSO + 2.5% egg yolk. Every treatment was conducted in three replicates. Combination of 5% DMSO + 5% egg yolk gave the best results cryoprotectant treatment had significant effects on sperm motility, fertilization and hatching rate of the R. tawarensis eggs (p < .05). It is concluded that the best proportion of cryoprotectants for sperm cryopreservation in this species is 5% DMSO + 5% egg yolk.  相似文献   

7.
The plasmid vector, pBRd-AK1-BGH4.6.10 (pBGH), containing the bovine growth hormone sequence driven by an avian retroviral long terminal repeat (LTR) was microinjected at 0.1, 0.5, 1 or 5 ng of pDNA/20 nl of physiological saline into tilapia, Oreochromis mossambicus × O. niloticus embryos. In 24 replicates, normally 60 zygotes were microinjected with either the entire linear 8.5 kb pBGH/ClaI vector or a 3.8 kb pBGH/SalI restriction fragment. Overall mean survival to fry hatching was 7.6% in plasmid DNA-microinjected, 15.6% in sham-microinjected and 48.1% in uninjected control embryos. There were no significant ( P > 0.05) differences in survival to hatching between those embryos microinjected with the 3.8 or the 8.5 kb restriction fragment, nor was there a trend toward decreasing survival as the plasmid DNA concentration increased from 0.1 to 5 ng. The significant ( P < 0.05) increase in survival among uninjected control embryos to hatching indicates that microinjection trauma was the major cause of mortality. Large quantities of plasmid DNA were recovered from pooled-embryo samples. Multiple bands (positive signals) were detected usually in the high molecular weight (HMW) genomic DNA regions. Position shifting of these HMW bands upon digesting with various restriction endonucleases provided evidence for plasmid DNA integration into tilapia embryo chromosomal DNA. Otherwise, these positive signah may have been end-twnd ligations of increasingly longer plasmid DNA constructs. Putative transgenic O. mossmbicus × O. niloticus were found among eight of 27 surviving adults.  相似文献   

8.
Experiments were carried out to develop an optimal cryopreservation protocol for tench sperm by testing the fertilizing capacity and motility parameters including progressive motility, curvilinear velocity (VCL) and linearity (LIN) of cryopreserved sperm. Three experiments were designed to this aim: first experiment where we tested the effects of two extenders (sugar‐based Grayling and ion‐based Kurokura 180) and two cryoprotectants (DMSO and methanol) on fertilization and hatching success; second where we tested the effect of cryoprotectant type (methanol or DMSO) in different concentrations (5%, 10% and 15%) on fertilization and hatching success; and third where we tested the effect of two cryoprotectants (methanol and DMSO) on sperm motility parameters (progressive motility, VCL and LIN) after 4 h post‐thaw storage (4°C). Sperm prepared with the sugar‐based Grayling extender displayed better fertilization and hatching rates independently of the applied cryoprotectant most likely due to glucose present which acted as an external cryoprotectant. Concerning cryoprotectant concentrations, the use of 10% methanol yielded the highest fertilization (85 ± 15%) and hatching (80 ± 13%) rates, which were significantly higher than in all other groups. During the post‐thaw storage time, 5% methanol, 10% methanol and 5% DMSO groups had significantly higher motility parameters than other groups and we observed no significant decline in any of the parameters during the storage time. Overall, we found that a sugar‐based extender in combination with methanol as cryoprotectant is suitable for the cryopreservation of tench sperm and allows storage of cryopreserved sperm for up to 4 h post thaw.  相似文献   

9.
We carried out an experiment to determine how rapidly the early incubation temperature of Atlantic cod eggs can be increased without affecting normal embryonic development and hatching. Atlantic cod eggs were incubated at a constant low temperature (4.5 ± 0.5°C; T5 – control) and four temperature increment treatments where the temperatures were increased stepwise from 4.5°C at zygote stage to 9.5 ± 05°C (T1‐8 h, T2‐32 h, T3‐64 h and T4‐96 h). Embryonic cell symmetry, embryonic mortality, hatching success and larval skeletal abnormalities, length and yolk sac volume were recorded. Larval samples were also taken at hatch for histological analysis. Except for higher egg mortality and lower hatching success in the T1, the differences among experimental groups were minor. Cell asymmetries and embryo mortalities were not significantly different between the control and T2–T4 treatment groups. Control larvae were significantly longer and had smaller yolk reserves at hatch than T1–T4 larvae and larvae from T2 had the largest yolk reserves. Tissue and organ histology of hatched larvae were similar. Considering embryonic cleavage pattern, hatching success and larval morphology and histology, a gradual increment of temperature in 32 h seems to be the better choice for future developmental programming studies in Atlantic cod.  相似文献   

10.
Temperature influenced the developmental rate, survival and early growth of eggs and embryos of spotted wolffish, Anarhichas minor (Olafsen), an interesting candidate for cold water cultivation. The total incubation period decreased from 220 days at 4 °C (880 daydegrees), to 177 days at 6 °C (1062 daydegrees) and 150 days at 8 °C (1200 daydegrees) in these experiments. The proportion of normal embryos and survival of eggs until hatching were highest when the eggs were incubated at 6 °C. During the incubation period, the embryo and yolk sac size at 280 daydegrees was not significantly different but at 850 daydegrees the embryo size was inversely related to temperature and the remaining yolk sac size positively correlated with the incubation temperature. The transformation of yolk to body mass during incubation appeared to be most efficient at 4 °C, and the embryos hatched with a larger visible yolk sac at 6 and 8 °C. The largest larvae (wet‐weight) hatched from the largest eggs and the egg groups incubated at the lowest temperature (4 °C). There was no effect of temperature on meristic characters. During 6 weeks post‐hatching, all larvae from the three temperature groups were fed formulated dry feed in excess at 8 °C in low water‐level raceway systems. During startfeeding, the larvae from eggs incubated at the lowest temperature (4 °C) showed the highest growth rates (SGR). Best survival of larvae was noted among batches incubated at 6 °C.  相似文献   

11.
Two egg batches of spotted wolffish, Anarhichas minor Olafsen, were incubated at 4, 6 and 8°C. Embryo samples were fixed and compared on each 100th daydegree until hatching (up to 1000 daydegrees). Embryos, yolk sacs and chorions were dissected and the sizes, wet and dry weights were recorded separately. Comparisons of gross morphologies and measured parameters showed increasing and generally significant differences with time between the incubation temperatures. Lower temperatures produced longer and more differentiated larvae at hatch with a smaller yolk sac. Even though some unexpected deviations were registered among batches and experimental groups, it was clear that temperature affected embryo survival and time of hatching. Overall survival was best at 6°C, in agreement with results from earlier studies. Yolk conversion efficiencies measured around the hatching point were generally high, ranging from 60% to 78%, varied between the two batches and probably reflected the developmental variations between embryos and larvae at the respective ages (daydegrees). The hatching process was apparently an energy‐demanding period; yolk conversion efficiencies of unhatched embryos of similar age at each temperature were always higher. Temperature is one environmental factor that can be manipulated in hatcheries to induce hatching of viable larvae at an optimal stage of differentiation with respect to first‐feeding success and early survival.  相似文献   

12.
This study aimed to evaluate the vitellogenic transference and incorporation of long‐chain polyunsaturated fatty acids (LC‐PUFA) into the membranes of Prochilodus lineatus embryos, aiming to increase the permeability to cryoprotectants and resistance to electric fields. One hundred thirty broodstock of P. lineatus were fed with control (C) or fish oil‐supplemented diets (FO) for 12 months. The fatty acid (FA) profle was determined using gas chromatography. For the neutral fraction, the FO group had a decrease in monounsaturated fatty acids (MUFA) and an increase in n3PUFA and, n6PUFA. To test for cryoprotectant toxicity, embryos were exposed for 20 min to a cryoprotectant solution of 1,2‐Propanediol (Prop) at a concentration of 5 or 6 molar (M). For FO, a reduction in survival of 33.1% was observed in 5 M, and no survival was observed at 6 M. Embryo samples were exposed the six polarized electric fields (3.4–51.6 joules), and with 11.2 J of energy, the control group exhibited reduced survival in 98.3% of the fish, whereas the FO presented superior resistance, exhibiting a survival similar to that of the OJ up to 40.2 J. We conclude that FA were transferred between P. lineatus broodstock to the embryos, with an increase in LC‐PUFA resulting in lower survival rates in the cryoprotectant test in the FO group and a greater physical plasticity of FO embryos to electrical field tests.  相似文献   

13.
Constant and oscillating egg incubation temperatures on embryonic development and early larval morphology were studied in longfin yellowtail (Seriola rivoliana Valenciennes). We investigated the effects of constant temperatures from 16 to 32°C on embryo development and larval morphology at hatch, and whether oscillating temperature during embryogenesis could lead to larval morphological variations. After hatching, larval morphology and development during yolk sac (YS) utilization were examined in larvae at constant temperatures and larvae at 25°C that had oscillating temperature during egg incubation. Hatching rates were > 75%, only decreasing to ~ 50% at 30°C. At constant temperatures, the largest larvae occurred at 22 and 24°C. The oscillating temperature did not affect the timing of embryo development but resulted in larger and smaller larvae with a smaller and bigger YS, respectively, with a similar hatching time. Therefore, a growth response occurred in embryos during a window of development before hatching, depending on the adaptive response to temperature (spawn‐specific). After hatching, most of the YS was absorbed within 24 hr in all treatments, and the growth of the larval head was a priority with an optimal development at 26°C. There was compensatory growth in smaller larvae resulting in similar sizes after YS utilization, but larvae showed variations in body structure that could be important in further aquaculture research.  相似文献   

14.
This study describes the effect of seasonal average temperatures (14 and 18°C) in the Ría of Vigo, on the utilization of external yolk over the last five Naef stages of development (XV–XX) for Octopus vulgaris embryos. Also, the transference of the outer yolk to the inner yolk sac, and its use during embryonic development and early life by O. vulgaris paralarvae. Temperature had a marked effect on embryonic development, except during stages XV–XIX (until the second inversion) where development time was the same (14 days), regardless of temperature. There were no significant differences in outer yolk decrease between consecutive Naef stages at 14°C and 18°C. Contrary, significant differences at all Naef stages from XV to XIX (both, with or without outer yolk) were observed for inner yolk between temperatures. A higher accumulation of inner yolk in embryos at 14°C was observed, due to lower yolk consumption. Paralarvae incubated at both temperatures were maintained independently at starvation during 4 days. At 18°C, a reduced accumulation of inner yolk, especially during Naef stage XIX, was observed. In 24 h old paralarvae, there was already significant higher inner yolk content at 14°C than at 18°C. Unfed paralarvae at 18°C lost weight faster than those at 14°C, due to higher energetic requirements. Finally, from these results, we propose a paralarvae rearing protocol during the first days after hatching and during the last five Naef stage (XV–XX) at lower temperatures, since the energy requirements are lower during the initial maturation stage.  相似文献   

15.
为了解超低温冷冻对胚胎形态结构的影响,以中华绒螯蟹为研究对象,运用石蜡切片、扫描电镜和透射电镜观察细胞分裂期、原肠期和原溞状幼体期胚胎,分别用玻璃化液处理和经超低温冷冻后外部形态和内部结构的变化。结果发现:(1)显微观察表明,细胞分裂期胚胎在玻璃化液中用二步平衡法处理后吸水膨胀明显,三步平衡后胚胎形态无明显变化,超低温冷冻后,卵黄物质从细胞中溢出,细胞破损严重;原肠期胚胎在玻璃化液中用二步平衡法处理后,外部形态与鲜胚无明显差异,经过冷冻后,所有胚胎内部变成粉红色,胚体由原来的透明变成不透明状,细胞膜边缘模糊似绒毛状;(2)扫描电镜观察,玻璃化液处理后的所有原肠期胚胎表面褶皱呈沟壑状,形成一层网状结构;透射电镜观察,处理后胚胎细胞内出现白色团块,细胞边缘变得粗糙有突起,细胞内冰腔清晰可见,空泡形成,80%以上线粒体解体,细胞破裂明显;(3)组织切片观察,原肠期胚胎细胞外面的膜脱落破损,胚层内有大小不一的冰腔,细胞内出现明显的空泡。原溞状幼体期胚胎经过玻璃化液处理后,外部形态与鲜胚间无明显区别,但经过超低温冷冻后,95%以上胚胎组织呈弥散状,部分卵黄物质碎裂成颗粒状,胚胎的细胞膜脱落,胚层内出现大量冰腔和空泡,90%胚胎表面皱缩凹陷,但仍有10%的胚胎表面保持光滑完整,表明原溞状幼体期胚胎是适合进行冷冻保存的时期。  相似文献   

16.
In the present study, attempts were made to preserve Urechis unicinctus sperm at 4°C. Cryopreservation procedures were optimized for various cryoprotectants and freezing rates, equilibration times and dilution ratios. During short‐term storage, the motility of undiluted sperm was extended for 6 days of cold storage,and in 70% and 100% artificial seawater only persisted for 2 and 4 days respectively. The survival rate of undiluted sperm was maintained at a high level accordingly. After cryopreservation, the highest motility and survival rate (41.5±2.2%) were obtained in 15% dimethyl sulphoxide (Me2SO) using a freezing rate of 30°C min?1. After thawing the sperm cryopreserved in glycerol lost almost all motility. The motility and survival rate of post‐thawing sperm did not show significant differences after 8 and 15 min equilibration using 15% Me2SO as cryoprotectant; the values were significantly higher than those of 2 min equilibration. Comparisons of motility and survival rate between treatments pooled by dilution ratio showed that the effect of 1:1 ratio (sperm volume to cryoprotectant volume) was best. There was no difference between 1:3 and 1:5, and other ratioswere significantly worse.  相似文献   

17.
《水生生物资源》2003,16(5):457-460
Experiments were carried out to investigate the effect of five extenders (sucrose, glucose, fructose, KCl and a saline carp sperm extender) and two cryoprotectants (dimethyl-sulfoxide (DMSO) and methanol) on the cryopreservation of common carp sperm. Freezing of sperm using glucose extender and methanol as cryoprotectant resulted in the highest post-thaw motility, fertilization as well as hatching rates (63 ± 9%, 74 ± 15% and 67 ± 17% vs. 87 ± 5%, 84 ± 14% and 69 ± 14% using fresh sperm, respectively). In general, sugar-based extenders combined with methanol as cryoprotectant yielded higher motility, fertilization and hatching rates than ionic extenders in combination with DMSO. The jelly-like agglutination observed after thawing in samples frozen with sugar-based extenders did not reduce fertilization and hatching rates. Frozen–thawed sperm samples were able to successfully fertilize 10 g (8000) eggs.  相似文献   

18.
The tolerance of striped trumpeter, Latris lineata (Bloch and Schneider 1801) embryos to ozonated seawater was examined as a possible means of disinfection. The effect of a range of ozone doses and exposures (CT = concentration × exposure time) was tested at different stages of embryonic development. Three-day-old embryos two-thirds developed around the yolk were exposed for 0.5, 1 or 5 min to ozone concentrations of 0.5, 1, 2 and 5 mg O3 l−1 in a fully orthogonal factorial design. For each treatment there were four replicate 250 ml containers that each received 100 ± 15 embryos. There was no significant difference in hatching success between control-treated embryos or embryos ozonated at 0.5 or 1 mg O3 l−1 for 0.5, 1 or 5 min (P < 0.05). However, hatching success was significantly reduced when embryos were treated with 2 or 5 mg O3 l−1 for 5 min or 5 mg l−1 O3 for 1 min (P < 0.05). The tolerance of embryos to 0, 0.5 or 2 mg O3 l−1 for 1 min at different stages of development (Day 0, 1, 2, 3 or 4), was then examined. An ozone concentration of 0.5 mg l−1 had no effect on hatching success at any stage of development, but a concentration of 2 mg l−1 significantly reduced hatching success on all days except Day 3. A safe and tested hatchery practise is to disinfect striped trumpeter embryos with 1 mg O3 l−1 for 1 min on Day 3 post-fertilisation when the embryo is two-thirds developed around the yolk.  相似文献   

19.
Chilled storage of zebrafish embryos is possible for up to 33 h at 8 °C without a loss in viability. In the present study, higher chilling temperatures in the range of 10–16 °C were tested to extend the storage periods to 65 h. It was also investigated whether prevention of microbiological growth with antibiotics and iodine, and stabilization of the quality of the storage solution by regular changes and constant aeration had an effect on the embryo and larvae viability. At incubation temperatures of 10 and 12 °C, the embryo development was completely arrested; at 14 and 16 °C, it proceeded slowly. At 10 °C, the percentage of embryos developing to the long‐pec stage was significantly lower than those at 12, 14 and 16 °C and in the control. At 10 and 12 °C, the percentage of embryos developing to the long‐pec stage decreased with increasing chilling period, while it remained constant at 14 and 16 °C. All chilling treatments resulted in low hatching rates <25% and many larvae showed malformations. Supplementation of storage solutions with antibiotics and iodine had no effect on the embryo and larvae viability, similar to regular solution changes and constant aeration.  相似文献   

20.
Based on the analysis of 11 morphometric variables of body (total length, body area and perimeter, myotome height and eye diameter) and yolk sac (length, height, area, perimeter and volume) of pike larvae, the aim of this study was to evaluate how larval size at hatching and growth of larvae hatched from single egg batches vary according to three hatching times: early, mid and late. Hatching time structures strongly pike larval morphometrics. Early hatched larvae have smaller body sizes at hatch, faster growth and higher yolk use efficiency than late hatched ones. Early hatched larvae seem to be premature and hatch at precocious developmental stage whereas late hatched individuals continue their growth within the egg shell and hatch at larger size but with lower reserves (yolk). A compensatory growth phase was observed for the early hatching pike larvae particularly during the first 5 days post hatch. Consequently, no significant difference in body parameters was recorded from day 10 post hatching whatever the hatching time. The higher growth accomplished by early hatched larvae may be related to a particular metabolic activity that converts more efficiently yolk into body tissues.  相似文献   

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