摘要
在温、湿度分别为 30℃、 - 2 2 0kPa条件下孵化中华鳖 (Pelodiscussinensis)卵 ,以检测孵化过程中胚胎生长及对物质和能量的利用。孵化过程中 ,每隔 7天测定卵重。孵化第 10天始 ,每隔 5天解剖 15枚卵 ,分离为胚胎、卵黄和卵壳。初生幼体称重后冰冻处死 ,随后解剖分离为躯干、剩余卵黄和脂肪体。所有样品 6 5℃恒温干燥 ,用索氏抽提仪测定脂肪含量 ,氧弹式热量计测定能量含量 ,马福炉测定无机物含量。本研究中华鳖卵的平均孵化期为 45 5天。卵重量在孵化过程中基本维持恒定 ,表明中华鳖卵与环境的水分交换不明显。孵化第0～ 2 0天、 2 0～ 30天、 30～ 40天和 40～ 45天 ,胚胎分别利用新生卵内总能量的 6 %、 2 4%、 5 9%和 4%。 0～ 30天 ,胚胎生长缓慢 ;30～ 40天 ,胚胎生长最迅速 ;孵化末期胚胎生长减缓。胚胎发育所需的无机物来自卵黄和卵壳 ;卵壳提供的无机物约占初生幼体无机物总量的 13 5 %。孵化过程中 ,干物质、脂肪和能量的转化率分别为 79 6 %、 5 8 7%和 6 6 5 %。初生幼体的能量组成为 :躯干占 71 8% ,脂肪体占 19 4% ,剩余卵黄占 8 8%。
We incubated a total of 132 Pelodiscus sinensis eggs at 30℃ using wet vermiculite as the incubation substrate, of which the moisture was kept constant at -220 kPa water potential. We paid particular attention to the growth trajectory of embryo and embryonic use of material and energy during incubation. Eggs were weighed at 7-day intervals to test for temporal changes in egg mass. From the tenth day of incubation, we opened 15 eggs at 5-day intervals and separated them into shell, embryo and yolk. The three egg components were oven dried to constant mass at 65℃, weighed and preserved frozen for later determination of composition. Upon emergence, size (carapace length and width) and mass were measured on each hatchling. Hatchlings (n =17) were then killed by freezing to -15℃ for later study. Upon thawing, we separated each hatchling into carcass, residual yolk and fat bodies. The three components were oven dried to constant mass at 65℃, weighed and preserved frozen for later determination of composition. We extracted non-polar lipids from dried samples in a Soxhlet apparatus for a minimum of 5.5 h using absolute ether as solvent. The amount of lipids in a sample was determined by subtracting the lipid-free dry mass from the total sample dry mass. The total lipid in each hatchling was calculated as the sum of the lipids in its carcass, residual yolk and fat bodies. We determined energy density of dried samples using an adiabatic bomb calorimeter and ash (inorganic material) content in each sample using a muffle furnace at 800℃ for a minimum of 8 h and then weighing the remaining ash. The incubating eggs did not show significant temporal changes in mass over the course of incubation, suggesting that mass gain or loss due to exchanges of water between incubating eggs and their surroundings was negligible in this study. The incubation length averaged 45.5 days. At the stage of 0～20, 20～30, 30～40 and 40～45 days of incubation, the developing embryos mobilized approximately 6%, 24%, 59% and 4% of the total egg energy in the yolk of the freshly laid egg, respectively. Embryos grew slowly during the first 30 days and last 5 days of incubation, as indicated by the small increase in embryo mass and the low rate of embryonic mobilization of energy. The maximum embryonic growth occurred at the stage of 30～40 days of incubation. The pattern that embryos grew slowly in the last days of incubation was much similar to that seen in some other turtles, presumably resulting from the synchronized emergence of hatchlings. Embryos used both yolk and eggshell as the sources of inorganic material for development, because total ash in newly emerged hatchling exceeded that in the yolk of the freshly laid egg. This claim could be further substantiated by the fact that shells from hatched eggs were lighter in mass and contained less quantities of ash than those from freshly laid eggs. During incubation, approximately 79.6% dry material, 58.7% non-polar lipids and 66.5% energy in egg contents of the freshly laid egg were transferred into the hatchling. Of all energy in the newly emerged hatchling, 71.8% was in the carcass, 19.4% in fat bodies and 8.8% in the residual yolk.
出处
《动物学报》
SCIE
CAS
CSCD
北大核心
2001年第4期371-375,共5页
ACTA ZOOLOGICA SINICA
基金
浙江省教育厅和浙江省自然科学基金青年人才专项基金资助项目&&
关键词
中华鳖
卵
孵化
幼体
物质代谢
能量动态
Soft-shelled turtle(Pelodiscus sinensis), Egg, Incubation, Hatchling, Material and energy dynamic
