北草蜥卵孵化过程中物质和能量的动态

Dynamics of material and energy during incubation in the grass lizardsTakydromus septentrionalis

研究北草蜥卵在温、湿度分别为 3 0℃、 -12kPa的条件下 ,孵化过程中物质和能量的动用以及胚胎生长。孵化过程中 ,每隔 5天称量卵重。孵化第 10天起 ,每隔 5天解剖来自不同窝的卵 15枚 ,并分离成胚胎、卵壳和卵黄三组分。孵出幼体称重后冰冻处死 ,之后解剖分离成躯干、剩余卵黄和脂肪体。所有材料 65℃烘至恒重 ,用索氏脂肪提取器测定脂肪含量 ,氧弹热量计测定能值 ,马福炉测定灰分含量。本研究北草蜥卵的孵化期为 2 8 1天。卵孵化时从基质中吸水导致重量增加。卵孵化 0 -10天、 11-2 0天、 2 1-2 5天、 2 6-2 8天 ,胚胎分别利用新生卵能量的 12 %、 3 5%、 3 7%和 15%。 0 -10天 ,胚胎生长较缓慢 ;10天后生长迅速。卵孵化过程中 ,干物质、非极性脂肪和能量的转化率分别为 69 7%、 3 7 0 %和 53 1%。初生幼体的能量组分为 :躯干95 2 % ,脂肪 2 4% ,剩余卵黄 2 4%。本研究结果显示 :北草蜥从新生卵到孵出幼体的物质和能量转化率较低 ;

We studied the growth of embryo and embryonic use of material and energy during incubation in t he grass lizards Takydromus septentrionalis, which were collected at Mount Langyashan, Chuzhou, Anhui, Eastern China from April to May, 2003. We removed eg gs, numbered, measured, weighed, and incubated them at 30℃ using wet vermiculit e as the incubation substrate, of which the moisture was kept at -12 kPa water p otential. Eggs were weighed at 5-day intervals to test for temporal changes in egg mass. From the tenth day of incubation, we randomly selected one egg from 15 clutches at 5-day intervals, opened and separated them into embryo, shell and yolk. The three egg components were oven dried to constant mass at 65℃ Hatchl i ngs were killed by freezing to -15℃ after being measured. We separated each hat chling into carcass, residual yolk and fat bodies. The three components were ov en dri ed to constant mass at 65℃. We extracted non-polar lipids from dried samples i n a Soxhlet apparatus for a minimum of 5 5 h using absolute ether as a solvent. We determined energy density of dried samples using an adiabatic bomb calorimet er and ash content in each sample using a muffle furnace at 700℃ for a minimum of 12 h and then weighing the remaining ash. Eggs increased in wet mass during i ncubation due to the absorption of water from the substrate. The duration of inc ubation averaged 28 1 days in this study. At the stage of 0-10, 11-20, 21-25,2 6-28 days of incubation, the developing embryos mobilized approximately 12%, 35% , 37% and 15% of the total egg energy in the yolk of the freshly laid egg, respe ctively. Embryos grew slowly during the first 10 days, the maximal embryonic gro wth occurred at the stage of 11-28 days of incubation. During incubation, approx imately 69 7% dry material, 37 0% non-polar lipids and 53 1% energy from the freshly laid egg were transferred to the hatchling. Of all energy in the newly emerged hatchling, 95 2% was in the carcass, 2 4% in fat bodies and 2 4% in t he residual yolk. Our results indicated that T septentrionalis exhibi ted relati vely low conversions of energy and material from the freshly laid egg to hatchin g. Embryos used both yolk and eggshell as the sources of inorganic material for development .