Tyrosinase (Tyr) Gene Mutation in Albino Mongolian Gerbil (Meriones unguiculatus)

Tyrosinase is encoded by the Tyr (c or albino) locus and is the key enzyme in pigment biosynthesis. Loss of function of this enzyme caused by gene mutation results in albinism. Most cases of albinism are caused by missense mutations of tyrosinase. Albino mutations in Tyr have been identified in various animals, including human, mouse, rat, rabbit, cattle, cat, and ferret, but not in gerbil. We created two new gerbil strains: MON/Num/a (inbred agouti phenotype) and MON/Num/c (albino phenotype). Here, we report that four nucleotide substitutions in the Tyr gene caused two missense mutations in amino acids in the albino gerbil: a G-to-A mutation at position 204 in exon 1 caused R77H, and A-to-G at position 1392 and G-to-T at position 1393 in exon 5 caused Q473R. The substitution at position 1408 in exon 5 was silent. These missense mutations are conserved in all albino phenotypes we tested. Therefore, we suggest that these mutations are responsible for albinism in gerbil.

Impairment of cellular and humoral immunity in overweight Mongolian gerbils (Meriones unguiculatus)

Animal immunity is usually impaired in obesity.We know little about the effect of being overweight or obese on the immune function of wild rodents.The present study is aimed to test the hypothesis that immunity is suppressed in overweight Mongolian gerbils(Meriones unguiculatus).In the study,16 overweight(body mass:90.8-127.6 g)and 16 lean gerbils(body mass:60.5-77.7 g)were randomly selected from a total of 174 male gerbils(body mass range:55.8-144.7 g).Half of the overweight and lean males were injected with sterile saline;the others were immunochallenged(IC)with phytohaemagglutinin and keyhole limpet hemocyanin to assess cellular and humoral immunity,respectively.Body fat mass,wet and dry spleen mass,leukocyte counts,blood glucose levels and serum leptin levels were significantly higher in the overweight gerbils than in the lean gerbils.However,phytohemagglutinin response indicative of cellular immunity and immunoglobulin G concentrations was significantly lower in the IC overweight gerbils than in the IC lean gerbils.These results indicate that cellular and humoral immunity are impaired in the overweight gerbils.Excessive body fat mass,higher leukocyte counts and serum leptin levels imply that overweight gerbils are in a low grade inflammatory state.

Relationship between climatic factors and the flea index of two plague hosts in Xilingol League,Inner Mongolia Autonomous Region

Climatic factors are closely associated with the occurrence of vector‐borne diseases,and they also influence the distribution of vectors.The occurrence of plague is closely related to the population dynamics of fleas and their host animals,as well as climatic conditions.This study focused on Xilingol League,utilizing climatic and flea index data from 2012 to 2021.Spearman correlation and"Boruta"importance analysis were conducted to screen for climatic variables.A generalized additive model(GAM)was employed to investigate the influence of climatic factors and rodent density on the flea index.GAM analysis revealed distinct trends in flea index among different rodent hosts.For Meriones unguiculatus,the flea index declined with increased density and with higher humidity,yet rose with greater lagged sunshine duration.For Spermophilus dauricus,an initial increase in flea index with density was observed,followed by a decrease,and a rise in the index was noted when ground temperatures were low.This study reveals the nonlinear interactions and lag effects among climatic factors,density,and flea index.Climatic factors and density variably influence the flea index of two Yersinia pestis hosts.This research advances the prediction and early warning efforts for plague control,providing a theoretical basis for rodent and flea eradication strategies.

Inter-group associations in Mongolian gerbils:Quantitative evidence from social network analysis

Animals often interact non-randomly with conspecifics,and association preferences can differ across life-histo­ry stages to maximize individuals’fitness.Mongolian gerbils(Meriones unguiculatus)are a social rodent that live in highly seasonal habitats and display seasonal fluctuations in population density,growth rate and the size of overlapped home ranges.Nevertheless,whether gerbils modify their social relationships at different life-his­tory stages remains unknown.Here,we used social network analysis to examine whether social associations dif­fer between the sexes and between life-history stages in a wild population of Mongolian gerbils.We quantified social attributes at both group level(assortativity)and individual level(social differentiation and degree,close­ness and betweenness centrality);these attributes reflect individuals’social preferences and their potential influ­ence on others in the network.We found that both male and female gerbils established fewer inter-group social connections during the food-hoarding season than during the breeding season,revealing constraints on sociali­ty.Similarly,during the food-hoarding season,degree centrality and social differentiation increased significant­ly whereas closeness and betweenness centrality decreased significantly.Together,these results suggest that ger­bils have relatively more partners and preferred associations and decreased influence over others in the network during the food-hoarding season.In addition,we found no significant difference in any of the social attribute be­tween males and females,but there was a significant interaction effect between sex and season on degree,close­ness and betweenness centrality.Our results demonstrate that Mongolian gerbils adjust their association strat­egies to adapt to the changes of life history.Such adjustments may balance the costs/benefits associated with survival and reproduction.

Effects of levonorgestrel-quinestrol(EP-1)treatment on Mongolian gerbil wild populations:a case study

Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands of Inner Mongolia,China.In 2009,we studied the contraceptive effect of levonorgestrel-quinestrol(EP-1),concentration 50 ppm,on a wild Mongolian gerbil population.The one-off contraceptive treatment was compared with a control group using a semi-monthly live trapping method in the Ordos Semi-desert Grassland Region of Inner Mongolia.The results show that juveniles were not recruited in spring in the treatment group.Ratios of juveniles in the control and treatment groups showed significant semi-monthly differences from spring to summer(one-way ANOVA,F_(2,14)=7.53,P<0.05).Between both groups,annual fluctuations of juvenile and total population densities were significantly different respectively(F_(2,14)=4.64,P<0.05;F_(2,18)=7.72,P<0.05).The contraceptive EP-1 delayed the normal reproductive pattern of Mongolian gerbil populations.This suppressed birth rates of gerbil populations,reduced their densities,and changed their age structures.The period of EP-1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.

Restricted dispersal determines fine-scale spatial genetic structure of Mongolian gerbils

Restricted gene flow may cause positive spatial genetic autocorrelation of animal populations at fine spatial scales. The Mongolian gerbil Meriones unguiculatus is a territorial, social rodent. Territoriality may create social fences to restrict dispersal or gene flow of Mongolian gerbils to a short distance. Restricted dispersal may differentiate fine-scale spatial genetic structure of populations with increasing distances （i.e., isolation by distance [IBD]）. Competition for mates and inbreeding avoidance may result in equal dispersal propensity and subsequently similar spatial genetic autocorrelation between males and females of monogamous gerbils. We genotyped 327 gerbils, live captured from 26 burrow systems on a 9-ha plot in northcentral Inner Mongolia, China, using seven microsateliite loci. Spatial genetic autocorrelation was positive within 80 m and became negative from 80 m to 200 m, suggesting restricted gene flow. Inter-group genetic and geographic distances were related positively, supporting the IBD model. Live trapping data demonstrated equal dispersal propensities of male and female gerbils. Restricted dispersal and social organization may determine fine-scale spatial population genetic structure of social rodents.