Fuel source shift or cost reduction:Context-dependent adaptation strategies in closely related Neodon fuscus and Lasiopodomys brandtii against hypoxia

Oxygen is essential for most life forms.Insufficient oxygen supply can disrupt homeostasis and compromise survival,and hypoxia-induced cardiovascular failure is fatal in many animals,including humans.However,certain species have adapted and evolved to cope with hypoxic environments and are therefore good models for studying the regulatory mechanisms underlying responses to hypoxia.Here,we explored the physiological and molecular responses of the cardiovascular system in two closely related hypoxiaadapted species with different life histories,namely,Qinghai voles(Neodon fuscus)and Brandt’s voles(Lasiopodomys brandtii),under hypoxic(10%O_(2) for 48 h)and normoxic(20.9%O_(2) for 48 h)exposure.Kunming mice(Mus musculus)were used for comparison.Qinghai voles live in plateau areas under hypoxic conditions,whereas Brandt’s voles only experience periodic hypoxia.Histological and hematological analyses indicated a strong tolerance to hypoxia in both species,but significant cardiac tissue damage and increased blood circulation resistance in mice exposed to hypoxia.Comparative transcriptome analysis revealed enhanced oxygen transport efficiency as a coping mechanism against hypoxia in both N.fuscus and L.brandtii,but with some differences.Specifically,N.fuscus showed upregulated expression of genes related to accelerated cardiac contraction and angiogenesis,whereas L.brandtii showed significant up-regulation of erythropoiesis-related genes.Synchronized upregulation of hemoglobin synthesis-related genes was observed in both species.In addition,differences in cardiometabolic strategies against hypoxia were observed in the rodents.Notably,M.musculus relied on adenosine triphosphate(ATP)generation via fatty acid oxidation,whereas N.fuscus shifted energy production to glucose oxidation under hypoxic conditions and L.brandtii employed a conservative strategy involving down-regulation of fatty acid and glucose oxidation and a bradycardia phenotype.In conclusion,the cardiovascular systems of N.fuscus and L.brandtii have evolved different adaptation strategies to enhance oxygen transport capacity and conserve energy under hypoxia.Our findings suggest that the coping mechanisms underlying hypoxia tolerance in these closely related species are context dependent.

Anti-fertility effect of levonorgestrel and quinestrol in Brandt’s voles(Lasiopodomys brandtii)

The combination of levonorgestrel and quinestrol(EP-1)has been shown to have anti-fertility effects on several wild rodents,but the mechanism underlying these effects is poorly understood.We investigated the effects of EP-1 and each of its components,levonorgestrel(P)and quinestrol(E),on the fertility of Brandt’s voles(Lasiopodomys brandtii)by using a gastric gavage method.The doses for EP-1,E and P were 1,0.34 and 0.66 mg/kg body weight,respectively.Male voles(n=98)were treated daily for 5 or 14 days,then the testes and epididymides were collected,weighed and examined histologically at 30(D30),60(D60)or 90(D90)days after the end of treatment.Four males were allowed to mate with normal females at D90.Female voles(n=75)were treated for 3 days and a further 3 days after a 7-day interval.The uteri and ovaries were weighed and examined histologically at 15(D15),30(D30)or 75(D75)days after the end of treatment.Each of three females were mated with fertile males at D30 and D75,respectively.Our results indicated that quinestrol(E)significantly decreased the sperm numbers in the testes as well as the weight of the testes and epididymides,with both of these tissues showing obvious structural abnormalities,and significantly reduced the litter size and the pup weight for females mated with males of the E treatment group.For female voles,treatment with E,P or EP-1 resulted in no marked influence on the fertility status.These data indicate that quinestrol(E)alone has a significant anti-fertility effect on male Brandt’s voles,but is ineffective in combination with levonorgestrel(P).

Effects of host identity on the gut microbiota:A comparative study on three microtinae species

Background:Gut microbiota exert an immense effect on host health and host environmental adaptation.Furthermore,the composition and structure of gut microbiota are determined by the environment and host genetic factors.However,the relative contribution of the environment and host genetic factors toward shaping the structure of gut microbiota has been poorly understood.Methods:In this study,we characterized the fecal microbial communities of the closely related voles Neodon fuscus,Lasiopodomys brandtii,and L.mandarinus after caged feeding in the laboratory for 6 months,through high-throughput sequencing and bioinformatics analysis.Results:The results of pairwise comparisons of N.fuscus vs.L.brandtii and L.mandarinus vs.L.brandtii revealed significant differences in bacterial diversity and composition after domestication.While 991 same operational taxonomic units(OTUs)were shared in three voles,there were 362,291,and 303 species-specific OTUs in N.fuscus,L.brandtii,and L.mandarinus,respectively.The relative abundances of Proteobacteria and Prevotella,which are reported to be enriched in high-altitude populations,were significantly higher in high-altitude N.fuscus than in low-altitude L.brandtii after domestication.Firmicutes,which produce various digestive enzymes for energy metabolism,and Spirochaetes,which can degrade cellulose,were found in higher abundance in subterranean L.mandarinus than that in L.brandtii which dwells on the earth surface.Conclusion:Our findings showed that some components of gut microbiota still maintained dominance even when different host species are reared under the same environmental conditions,suggesting that these bacteria are substantially influenced by host factors.

温度驯化对布氏田鼠肝脏温敏瞬时受体电位通道蛋白表达的影响

肝脏是哺乳动物基础代谢产热的关键器官。温敏瞬时受体电位通道蛋白(Thermosensitive transient receptor potential channels,Thermo-TRPs)参与了调控肝细胞的生理功能。为了解Thermo-TRPs是否参与肝脏的代谢产热,以成年布氏田鼠(Lasiopodomys brandtii)为研究对象,测定了不同驯化温度下6种Thermo-TRPs在肝脏中的表达,分析其与肝脏产热相关蛋白和信号通路蛋白的关系。结果显示:(1)与高温组相比,低温增加了肝脏解偶联蛋白1(uncoupling protein 1,UCP1)的表达;而与常温组相比,低温降低了肝脏解偶联蛋白3(uncoupling protein 3,UCP3)的表达;(2)6种Thermo-TRPs均在肝脏中表达,与高温组相比,低温显著降低了TRP vanilloid 4(TRPV4)的表达,同时显著增加了腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)的表达;(3)低温显著增加了布氏田鼠血清三碘甲状腺原氨酸(T_(3))水平,提高了T_(3)/T_(4)比值;T_(3)/T_(4)比值与肝脏UCP1和AMPK呈显著正相关,肝脏中UCP1与TRPM2和AMPK呈显著正相关。这些结果表明,肝脏TRPV4和AMPK可能参与了低温环境中代谢产热等生理功能的调节过程。