Powell Mickie L, Watts Stephen A
Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294-1170, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2006 Jun;144(2):211-7. doi: 10.1016/j.cbpa.2006.02.032. Epub 2006 Mar 3.
Procambarus clarkii and Procambarus zonangulus are two of the most widespread crayfish species in North America. In regions where their ranges overlap species composition can vary greatly. The physiological basis for this variable species composition is unknown. Temperature and oxygen level are two parameters that vary in shallow water habitats. We examined the metabolic rate and hemocyanin binding affinities in relation to thermal history. Temperature acclimation did not have the predicted effect on metabolic rate. Acclimation to high temperature (30 degrees C) decreased metabolic rate at 35 degrees C for both species. Low temperature acclimation (10 degrees C) resulted in 20% mortality in P. clarkii and 100% mortality in P. zonangulus when exposed to 35 degrees C. The range of P. clarkii is known to extend farther south than that of P. zonangulus, and this response may be a consequence of adaptations to higher temperatures in this range. Hemocyanin binding affinity was directly affected by assay and acclimation temperature. The highest P(50) values were recorded for crayfish of both species acclimated to 10 degrees C and assayed at 30 degrees C. There was also a shift in the isoelectric points of hemolymph proteins (possibly due to structural changes) that correlated with and an increase in the hemocyanin binding affinity following acclimation to high temperatures (30 degrees C) in both species.
克氏原螯虾和带纹原螯虾是北美分布最广泛的两种小龙虾。在它们分布范围重叠的地区，物种组成可能有很大差异。这种可变物种组成的生理基础尚不清楚。温度和氧气水平是浅水栖息地中变化的两个参数。我们研究了与热历史相关的代谢率和血蓝蛋白结合亲和力。温度驯化对代谢率没有产生预期的影响。对于这两个物种，高温驯化（30摄氏度）均降低了35摄氏度时的代谢率。低温驯化（10摄氏度）导致克氏原螯虾在暴露于35摄氏度时有20%的死亡率，带纹原螯虾则有100%的死亡率。已知克氏原螯虾的分布范围比带纹原螯虾更向南延伸，这种反应可能是该范围内适应较高温度的结果。血蓝蛋白结合亲和力直接受测定和驯化温度的影响。对于两种适应10摄氏度并在30摄氏度下测定的小龙虾，记录到了最高的P(50)值。在两种物种中，血淋巴蛋白的等电点也发生了变化（可能由于结构变化），这与高温驯化（30摄氏度）后血蓝蛋白结合亲和力的增加相关。
