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861.
William S. Bugg Gwangseok R. Yoon Catherine Brandt Madison L. Earhart W. Gary Anderson Ken M. Jeffries 《Journal of fish biology》2021,99(6):1912-1927
In Manitoba, Canada, wild lake sturgeon (Acipenser fulvescens) populations exist along a latitudinal gradient and are reared in hatcheries to bolster threatened populations. We reared two populations of lake sturgeon, one from each of the northern and southern ends of Manitoba and examined the effects of typical hatchery temperatures (16°C) as well as 60-day acclimation to elevated rearing temperatures (20°C) on mortality, growth and condition throughout early development. Additionally, we examined the cold shock response, which may be induced during stocking, through the hepatic mRNA expression of genes involved in the response to cold stress and homeoviscous adaptation (HSP70, HSP90a, HSP90b, CIRP and SCD). Sturgeon were sampled after 1 day and 1 week following stocking into temperatures of 8, 6 and 4°C in a controlled laboratory environment. The southern population showed lower condition and higher mortality during early life than the northern population while increased rearing temperature impacted the growth and condition of developing northern sturgeon. During the cold shock, HSP70 and HSP90a mRNA expression increased in all sturgeon treatments as stocking temperature decreased, with higher expression observed in the southern population. Expression of HSP90b, CIRP and SCD increased as stocking temperature decreased in northern sturgeon with early acclimation to 20°C. Correlation analyses indicated the strongest molecular relationships were in the expression of HSP90b, CIRP and SCD, across all treatments, with a correlation between HSP90b and body condition in northern sturgeon with early acclimation to 20°C. Together, these observations highlight the importance of population and rearing environment throughout early development and on later cellular responses induced by cold stocking temperatures. 相似文献
862.
The thermal transition of a non-hydroxylated form of collagen. Evidence for a role for hydroxyproline in stabilizing the triple-helix of collagen 总被引:21,自引:0,他引:21
Protocollagen, a non-hydroxylated form of collagen, was extracted with cold 0.1 N acetic acid from embryonic tendon cells incubated with α,α′-dipyridyl and the protein was purified by controlled proteolytic digestion. The resulting modified protocollagen was shown to consist of polypeptides the same size as α1 and α2 chains of collagen and had a thermal transition by optical rotation similar to collagen. The Tm however was 24°, a value which was 15° lower than the Tm of an hydroxylated form of collagen from the same source. The results suggest that hydroxylated proline increases the thermal stability of collagen. 相似文献
863.
The response of communities to climate extremes can be quite variable. Much of this variation has been attributed to differences in community‐specific functional trait diversity, as well as community composition. Yet, few if any studies have explicitly tested the response of the functional trait structure of communities following climate extremes (CEs). Recently in South Florida, two independent, but sequential potential CEs took place, a 2010 cold front, followed by a 2011 drought, both of which had profound impacts on a subtropical estuarine fish community. These CEs provided an opportunity to test whether the structure of South Florida fish communities following each extreme was a result of species‐specific differences in functional traits. From historical temperature (1927–2012) and freshwater inflows records into the estuary (1955–2012), we determined that the cold front was a statistically extreme disturbance, while the drought was not, but rather a decadal rare disturbance. The two disturbances predictably affected different parts of functional community structure and thus different component species. The cold front virtually eliminated tropical species, including large‐bodied snook, mojarra species, nonnative cichlids, and striped mullet, while having little affect on temperate fishes. Likewise, the drought severely impacted freshwater fishes including Florida gar, bowfin, and two centrarchids, with little effect on euryhaline species. Our findings illustrate the ability of this approach to predict and detect both the filtering effects of different types of disturbances and the implications of the resulting changes in community structure. Further, we highlight the value of this approach to developing predictive frameworks for better understanding community responses to global change. 相似文献
864.
865.
五种植物抗寒性的比较研究 总被引:3,自引:0,他引:3
采用电导法对五种植物(四种美国引进的植物和一种乡土植物)进行不同低温处理,研究其在各温度下的细胞膜透性改变情况,并配以Logistic方程求拐点值确定低温半致死温度LT50。结果表明:低温处理下各种植物组织电解质渗透率增加,并呈"S"形曲线增长,各种植物的低温半致死温度分别为:沙地柏为-46.58℃,四翅滨藜-1,四翅滨藜-2分别为-42.44℃和-40.09℃,黑油脂木为-27.7℃,伏地肤为-22.18℃。故其抗寒性从强到弱的顺序为沙地柏>四翅滨藜-1>四翅滨藜-2>驼绒藜>黑油脂木>伏地肤。 相似文献
866.
867.
Claessens-van Ooijen AM Westerterp KR Wouters L Schoffelen PF van Steenhoven AA van Marken Lichtenbelt WD 《Obesity (Silver Spring, Md.)》2006,14(11):1914-1920
Objective: To compare overweight and lean subjects with respect to thermogenesis and physiological insulation in response to mild cold and rewarming. Research Methods and Procedures: Ten overweight men (mean BMI, 29.2 ± 2.8 kg/m2) and 10 lean men (mean BMI, 21.1 ± 2.0 kg/m2) were exposed to cold air for 1 hour, followed by 1 hour of rewarming. Body composition was determined by hydrodensitometry and deuterium dilution. Heat production and body temperatures were measured continuously by indirect calorimetry and thermistors, respectively. Muscle activity was recorded using electromyography. Results: In both groups, heat production increased significantly during cooling (lean, p = 0.004; overweight, p = 0.006). The increase was larger in the lean group compared with the overweight group (p = 0.04). During rewarming, heat production returned to baseline in the overweight group and stayed higher compared with baseline in the lean group (p = 0.003). The difference in heat production between rewarming and baseline was larger in the lean (p = 0.01) than in the overweight subjects. Weighted body temperature of both groups decreased during cold exposure (lean, p = 0.002; overweight, p < 0.001) and did not return to baseline during rewarming. Discussion: Overweight subjects showed a blunted mild cold‐induced thermogenesis. The insulative cold response was not different among the groups. The energy‐efficient response of the overweight subjects can have consequences for energy balance in the long term. The results support the concept of a dynamic heat regulation model instead of temperature regulation around a fixed set point. 相似文献
868.
Katie E. Marshall Brent J. Sinclair 《Proceedings. Biological sciences / The Royal Society》2010,277(1683):963-969
While insect cold tolerance has been well studied, the vast majority of work has focused on the effects of a single cold exposure. However, many abiotic environmental stresses, including temperature, fluctuate within an organism''s lifespan. Given that organisms may trade-off survival at the cost of future reproduction, we investigated the effects of multiple cold exposures on survival and fertility in the model organism Drosophila melanogaster. We found that multiple cold exposures significantly decreased mortality compared with the same length of exposure in a single sustained bout, but significantly decreased fecundity (as measured by r, the intrinsic rate of increase) as well, owing to a shift in sex ratio. This change was reflected in a long-term decrease in glycogen stores in multiply exposed flies, while a brief effect on triglyceride stores was observed, suggesting flies are reallocating energy stores. Given that many environments are not static, this trade-off indicates that investigating the effects of repeated stress exposure is important for understanding and predicting physiological responses in the wild. 相似文献
869.
冷应激对雏鸡能量代谢的影响 总被引:1,自引:0,他引:1
目的:探讨冷应激对雏鸡能量代谢的影响。方法:采用公雏鸡为实验动物,进行急性(0.25,1,3,6,12与24h)与慢性(5,10与20d)冷应激处理(12±1℃),检测了雏鸡腓肠肌解偶联蛋白(UCP)mRNA的表达水平,血清葡萄糖(BG),游离脂肪酸(FFA),胰岛素(INS)以及血浆胰高血糖素(GLU)的含量。结果:急性应激时,UCP mRNA的水平随应激时间的延长呈上升趋势,INS与FFA含量随应激时间的延长呈现波动性变化,GLU含量随应激时间的延长呈现上升趋势,BG含量随应激时间的延长呈现先升高后降低的趋势;慢性应激时,UCP mRNA的水平随应激时间的延长呈上升趋势,INS、GLU、BG以及FFA含量随应激时间的延长均呈上升趋势。结论:冷暴露可以使雏鸡的能量代谢发生改变,而且不同程度的冷应激对机体的能量代谢会产生不同的影响。 相似文献
870.
Antonia Otte Johanna C. Winder Longji Deng Jeremy Schmutz Jerry Jenkins Igor V. Grigoriev Amanda Hopes Thomas Mock 《Journal of phycology》2023,59(2):301-306
Diatoms are significant primary producers especially in cold, turbulent, and nutrient-rich surface oceans. Hence, they are abundant in polar oceans, but also underpin most of the polar food webs and related biogeochemical cycles. The cold-adapted pennate diatom Fragilariopsis cylindrus is considered a keystone species in polar oceans and sea ice because it can thrive under different environmental conditions if temperatures are low. In this perspective paper, we provide insights into the latest molecular work that has been done on F. cylindrus and discuss its role as a model alga to understand cold-adapted life. 相似文献