Epidemiological Predicting of the Fleas on Rattus norvegicus

[Objective]To predict prevalence of fleas via a simple epidemiological model.[Method]The field investigation was carried out in 23 locations in Yunnan Province.A simple epidemiological model was involved mean abundance and variance of abundance.[Result]The prevalence of fleas increased with their mean abundance in logistic curve.A linear correlation of the predicted prevalence against observed prevalence did not differ significantly from unity.[Conclusion]Prevalence could be explained simply by their mean abundance.

RNA Interference-Mediated Downregulation of sAC Gene Inhibits Sperm Hyperactivation in Male Rats(Rattus norvegicus)

Hyperactivation is one of the most critical parts for fertilization, cAMP generated by soluble adenylyl cyclase （sAC） is necessary to activate sperm and is a prerequisite for sperm hyperactivation. The aim of this study is to investigate the function of sAC in hyperactivation in male rats. Four siRNAs of sAC gene were designed and separately transformed into rat sperm using electrotransformation method. Cultured for 12 and 24 h, physiological and biochemical indexes of these sperm were analyzed, and the expressions of some hyperactivation-related genes were detected using real-time PCR. We demonstrated 26.3-30.8% and 49.1-50.5% reduction in sAC at the protein by Western blot and mRNA levels by real-time PCR, respectively. The results showed that two siRNAs, Actb-717 and Actb-4205, were the best RNAi sites for silencing sAC. The VCL （curvilinear velocity） and ALH （amplitude of lateral head displacement） of RNA interference （RNAi）-transfected sperm were reduced, cAMP and protein phosphorylation in RNAi transfected sperm were also decreased. The hyperactivation-related genes, such as CatSper2, LDHC and PKA, were downregulated in the sperm, which sAC was knockdown. These findings demonstrated that sAC might play a critical role in cAMP signaling in the rat sperm hyperactivation, and downregulated sAC gene might prevent the expression of these hyperactivation-ralated genes resulting in sperm dysfunction. These findings suggest that these hyperactivation-ralated genes and sAC are functionally related in sperm hyperactivation and sAC falls into an expanding group of sperm proteins that appear to be promising targets for the development of male contraceptives.

Efficacy of anticoagulant-free alternative bait products against house mice(Mus musculus)and brown rats(Rattus norvegicus)

The attractiveness and efficacy of four anonymous anticoagulant-free alternative rodenticides(active ingredients cellulose or plaster)were tested on wild strain groups of house mice(Mus musculus Linnaeus)and brown rats(Rattus norvegicus Berkenhout)in laboratory choice and no-choice experiments.In no-choice tests,the rodenticide product was offered ad libitum to the animals for 21 days(mice)and 10 days(rats),respectively.In choice tests,the rodenticide product and non-poisoned food were offered for 28 days(mice)and 14 days(rats).Two products with cellulose(C1 and C2)as the active ingredient were tested against both mice and rats.In two no-choice tests with mice,all animals died within 14 days(C1)and 21 days(C2);in a third no-choice test,11%(2/18)of mice survived(C1:21 days).In all three tests,numerous incidents of cannibalism were observed.The attractiveness of cellulose baits was tested for one product(C1)in three trials against normal food pellets.In all trials,bait consumption was low and all mice survived(15-34 days).Two no-choice trials with cellulose baits(C1)were conducted on groups of Rattus norvegicus;11 of 12 rats survived the bait feeding period and no cannibalism or sign of aggression between conspecifics was observed.Two plaster-based(CaSO_(4)·0.5H_(2)O)products(P1 and P2)were tested against both mice and rats;in no-choice tests,only one mouse(n=20)and no rats(n=8)were killed,although the baits proved to be attractive for rats and mice in choice tests.The results of these experiments suggest that neither cellulose-based nor plaster-based rodenticides are suitable agents for the control of Mus musculus and Rattus norvegicus.

Pitx2 suppression at meiotic stages associates with seasonal inhibition of testis development in Rattus norvegicus caraco

The bicoid-related transcription factor 2(Pitx2)plays a crucial role in the development of many organs and tissues by affecting the mitotic cell cycle.Postnatal testis development is related to mitosis and meiosis in mul-tiple cell types,but the role of Pitx2 gene in seasonal inhibition of testicular development remains unknown in rodents.We analyzed PITX2 protein and Pitx2 mRNA expression features using both laboratory and wild male Rattus norvegicus caraco.In postnatal testicle of laboratory colony,we found that PITX2 was expressed in Leydig cells,pachytene spermatocytes,round spermatids,and elongating spermatids rather than spermatogonia and lep-totene/zygotene spermatocytes.Pitx2b expression significantly increased along with the occurrence of pachytene spermatocytes and round spermatids,while decreased along with the processes of elongated spermatids.In wild male rats with similar testes weight,a significantly suppressed Pitx2b expression occurred with an active meiotic stage in the inhibited testes in autumn and winter,compared with the normally developing testes in spring and summer.These results indicate that Pitx2b expression suppression plays a crucial role in the seasonal inhibition of testis development.

褐家鼠与大仓鼠消化系统比较

为了解褐家鼠(Rattus norvegicus)与大仓鼠(Cricetulus triton)消化系统之间的差异,试验对两种鼠进行解剖。结果表明,褐家鼠食管平均长度占体长比值是大仓鼠的0.873倍;胃(不含内容物)的平均质量占体重比值是大仓鼠的0.462倍;小肠平均长度占体长的比值是大仓鼠的1.557倍,大肠平均长度占体长比值是大仓鼠的0.383倍,盲肠平均长度占体长比值是大仓鼠的0.283倍;肝重与体重比值是大仓鼠的1.190倍。两种鼠的消化系统中器官长度和结构有多处差异,两种鼠对于食物质量选择的分化程度明显,且褐家鼠食物选择广泛,大仓鼠对植物性食物依赖性更高。

Biochemical and histopathological profiling of Wistar rat treated with Brassica napus as a supplementary feed

Metabolic changes together with cardiovascular and hepatic factors are related to the development of diseases like myocardial lipidosis,heart disease,and profound toxicity.The aim of this animal study is to determine the effects of high erucic acid containing rapeseed oil(Brassica napus L.)varieties on liver,kidney and heart muscles in Wistar rats.Male Wistar rats were divided into three groups where each group containing four rats.Group A was considered as control diet group,while Group B rapeseed wild oil group and Group C rapeseed hybrid oil group were considered as experimental diet groups.The levels of aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(ALP),creatine kinase-MB(CK-MB)and creatinine of two experimental groups were significantly elevated while compared to the control groups(p<0.05–0.001).Nevertheless,an increment in weight retardation(p<0.05)was also observed in rapeseed hybrid oil treated groups.No significant weight retardation found in other two groups(p>0.05).Noticeable tissue injury observed in this study is a sign of the relative toxicity of erucic acid containing rapeseed oil to mammalian species.The use of Brassica napus as a supplementary feed ingredient should be,therefore,thoroughly considered.

A comparative analysis of differentially expressed genes in rostral and caudal regions after spinal cord injury in rats

The initial mechanical damage of a spinal cord injury(SCI)triggers a progressive secondary injury cascade,which is a complicated process integrating multiple systems and cells.It is crucial to explore the molecular and biological process alterations that occur after SCI for therapy development.The differences between the rostral and caudal regions around an SCI lesion have received little attention.Here,we analyzed the differentially expressed genes between rostral and caudal sites after injury to determine the biological processes in these two segments after SCI.We identified a set of differentially expressed genes,including Col3a1,Col1a1,Dcn,Fn1,Kcnk3,and Nrg1,between rostral and caudal regions at different time points following SCI.Functional enrichment analysis indicated that these genes were involved in response to mechanical stimulus,blood vessel development,and brain development.We then chose Col3a1,Col1a1,Dcn,Fn1,Kcnk3,and Nrg1 for quantitative real-time PCR and Fn1 for immunostaining validation.Our results indicate alterations in different biological events enriched in the rostral and caudal lesion areas,providing new insights into the pathology of SCI.

Genetic boundary and gene flow between 2 parapatric subspecies of brown rats

Two parapatric Rattus norvegicus subspecies,R.n.humiliatus(RNH)and R.n.caraco(RNC),are classified accordi ng to morphological diverge nee and are mainly distributed in North and Northeast China.Here,we aimed to explore the population genetic structure,genetic boundary,and gene flow in these rats using 16 microsatellite loci.Structure analysis and principal component an alysis revealed 3 ancestral clusters.We found that the in termediate cluster exhibited higher genetic diversity and a lower in breeding coefficie nt tha n the other 2 clusters.The genetic differentiation between the 3 clusters was significant but weak,with a higher FST value being observed betwee n the clusters on both sides.The subspecies bou ndary inf erred from microsatellite markers may indicate the existence of an admixture or hybridization area covering Liaoning,Inner Mongolia,and Jilin Provinces,rather than corresponding to the administrative provincial boundaries between Liaoning and Jilin.The RNH and RNC subspecies presented moderate gene exchange and an asymmetric bidirectional gene flow pattern,with higher gene flow from the RNH subspecies to the RNC subspecies,constraining speciation.Such genetic characteristics might be explained by biological processes such as dispersal ability,mate choice,and dynamic lineage boundaries.

Phylogenetic analysis based on mitochondrial DNA sequences of wild rats, and the relationship with Seoul virus infection in Hubei, China

Seoul virus(SEOV), which is predominantly carried by Rattus norvegicus, is one of the major causes of hemorrhagic fever with renal syndrome(HFRS) in China. Hubei province, located in the central south of China, has experienced some of the most severe epidemics of HFRS. To investigate the mitochondrial DNA(mt DNA)-based phylogenetics of wild rats in Hubei, and the relationship with SEOV infection, 664 wild rats were captured from five trapping sites in Hubei from2000–2009 and 2014–2015. Using reverse-transcription(RT)-PCR, 41(6.17%) rats were found to be positive for SEOV infection. The SEOV-positive percentage in Yichang was significantly lower than that in other areas. The mt DNA D-loop and cytochrome b(cyt-b) genes of 103 rats were sequenced.Among these animals, 37 were SEOV-positive. The reconstruction of the phylogenetic relationship(based on the complete D-loop and cyt-b sequences) allowed the rats to be categorized into two lineages, R. norvegicus and Rattus nitidus, with the former including the majority of the rats. For both the D-loop and cyt-b genes, 18 haplotypes were identified. The geographic distributions of the different haplotypes were significantly different. There were no significant differences in the SEOVpositive percentages between different haplotypes. There were three sub-lineages for the D-loop,and two for cyt-b. The SEOV-positive percentages for each of the sub-lineages did not significantly differ. This indicates that the SEOV-positive percentage is not related to the mt DNA D-loop or cyt-b haplotype or the sub-lineage of rats from Hubei.