低温对红耳龟血液指标及植物血凝素反应的影响

Effects of Low Temperature on Hematological Indices and Response to Phytohemagglutinin in the Red-eared Slider Turtle,Trachemys scripta elegans

探究低温对红耳龟(Trachemys scripta elegans)免疫功能和应激反应能力的影响,揭示红耳龟适应低温环境的生理学和免疫学基础,为深入了解其入侵生物学提供基础资料。采用活体背甲下静脉窦采血技术,测定了6℃、17℃和26℃条件下处理1、5和10 d时血液中各型白细胞百分比及嗜异性粒细胞与淋巴细胞的比值(ratio of heterophils to lymphocytes,H/L),以及第10天采血后植物血凝素(phytohemagglutinin-P,PHA-P)反应的变化。结果显示:(1)随着温度下降,第1天只有嗜碱性粒细胞的百分比显著升高(P<0.05),此差异在第5天和第10天消失(P>0.05);第5天,嗜酸性粒细胞的百分比和H/L先升后降,淋巴细胞的百分比先降后升,单核细胞的百分比下降(P<0.05);第10天,嗜酸性粒细胞的百分比上升,淋巴细胞、嗜异性粒细胞和单核细胞的百分比,以及H/L下降(P<0.05);(2)随着处理天数延长,除嗜碱性粒细胞的百分比无组内差异外(P>0.05),其他类型白细胞的百分比及H/L都有组内差异(P<0.05);(3)6℃组、17℃组和26℃组对PHA-P的反应分别在注射后48 h、24 h和48 h达到峰值,但组间差异不显著(P>0.05)。红耳龟通过调整血液中嗜酸性粒细胞等不同类型白细胞的百分比、下降的应激反应能力和提前发生反应的免疫应答来适应低温的短期胁迫。

In this study,we explored the effects of low temperatures on immune function and stress response in the red-eared slider turtle,Trachemys scripta elegans.Our aim was to reveal the physiological and immunological mechanisms of their adaptation to low-temperature environments,and provide basic data on their biological behavior as an invasive species.Healthy red-eared slider turtles purchased at the flower fair were exposed to three water temperatures(6℃,17℃,and 26℃)for 10 days,with 10 turtles in each group.On day 1,5 and 10,blood samples were collected from the dorsal cervical sinus and body mass,carapace length and width were measured.The percentage of different leukocytes and the ratio of heterophils to lymphocytes(H/L)were determined,and their response to the antigen,phytohemagglutinin-P(PHA-P),was measured on day 10 after collecting blood samples.Results were as follows:(1)Temperature and time had no significant effects on or interaction with body mass,carapace length and width.On day 1,the percentage of basophils significantly increased at 6℃and 17℃(P<0.05),but this effect was not observed on day 5 and day 10(P>0.05).On day 5,the percentage of eosinophils and H/L increased and then decreased,the percentage of lymphocytes initially decreased and then increased,while the percentage of monocytes tended to decrease(P<0.05).On day 10,the percentage of eosinophils increased,but the percentage of lymphocytes,heterophils and monocytes,and H/L decreased(P<0.05).(2)After 10 days,the percentage of leukocytes,except for the basophils and H/L,showed significant differences within temperature groups(P<0.05).(3)The response of the red-eared slider turtles to the PHA-P antigen peaked at 48 h,24 h,and 48 h after injection in the 6℃,17℃,and 26℃groups,respectively,with no significant differences among the temperature groups(P>0.05).Red-eared slider turtles adapt to short-term low temperature stress by adjusting the proportions of different types of leukocytes,reducing stress response capacity,and altering immune response timing.