Demonstration of serum albumin (ALB) polymorphism in wild rabbits, Oryctolagus cuniculus, by means of isoelectric focusing

Summary. Genetic polymorphism of serum albumin was demonstrated by isoelectric focusing in wild rabbit populations from Portugal and England. Gene frequencies were estimated to be (1) ALB*1 = 0.47, ALB*2 = 0.49, ALB *3 = 0.04, in Portugal, and (2) ALB*1 = 0.60 and ALB*2 = 0.40, in England. One hundred Portuguese domestic rabbits of mixed breeds were all of ALB 1 type.     

Genetic polymorphism of delta-aminolaevulinic acid dehydratase (E.C. 4.2.1.24, ALAD) in the domestic rabbit

A genetic polymorphism of delta-aminolaevulinic acid dehydratase (ALAD) in the domestic rabbit, Oryctolagus cuniculus, was detected by starch gel electrophoresis. Family data (15 matings with 49 offspring) support the genetic model of two common codominant alleles at an autosomal locus. Gene frequencies were calculated in a random sample of 55 mixed breed, unrelated domestic rabbits: ALAD1 = 0.31 and ALAD2 = 0.69.     

Genetics of a tissue esterase polymorphism (Est-6) in the rabbit (Oryctolagus cuniculus)

Genetic analysis of a polymorphic tissue esterase revealed a new locus (Est-6) with two alleles (Est-6 ^a andEst-6 ^b) on linkage group VI of the rabbit.Est-6 is closely linked to theEst-1,2,4 cluster. Esterase ofEst-6 is found in many organs, particularly in liver and small intestine, but not in erythrocytes and serum.Est-6 esterase hydrolyzes -naphthyl acetate and butyrate, naphthol AS-D acetate, indoxyl acetate, and butyrate as well as 5-bromoindoxyl acetate,N-acetyl-l-alanine--naphthyl ester but not 4-methylumbelliferyl acetate and fluorescein diacetate. The enzyme is inhibited by bis-p-nitrophenyl phosphate and eserine but not byp-chloromercuribenzoate. It was classified as a carboxylesterase (EC 3.1.1.1). Based on chromosomal localization, tissue distribution, substrate specificity, inhibitor sensitivity, and range ofpI's, rabbitEst-6 is assumed to be homologous with mouseEs-7.The contribution of Dr. O. von Deimling (No. 59) was supported by the Deutsche Forschungsgemeinschaft (De 315/2-2).     

High levels of nucleotide diversity in the European rabbit (Oryctolagus cuniculus) SRY gene

We have sequenced 2,388 bp of the European rabbit sex determining region Y (SRY) gene. These data provide a 10-fold increase in the coverage of the Y chromosome in this species, including the entire open reading frame of the SRY, the polyadenylation signal, and two repetitive sequences in the 5' -region. A survey of 2021 bp of this gene in eight domestic breeds and four wild individuals revealed a total of nine single nucleotide polymorphisms and one indel, defining two deeply divergent lineages. The resulting estimation of nucleotide diversity (pi=1.34 x10(-3)) is very high when compared with other species, but no variability was detected among the domestic breeds. This study represents a first step in the characterization of the European rabbit Y chromosome and its variability. These sequences can be used in additional phylogeographical analyses of the European rabbit and other Leporid species, as well as in evolutionary studies of sex determination and the Y chromosome in wild species.     

Coccidiosis of the wild rabbit (Oryctolagus cuniculus) in France

In 1998-1999 a survey of coccidiosis in wild rabbits was carried out in six different localities in France. About five individuals were caught monthly in each locality and a total of 254 wild rabbits was examined. Ten species of Coccidio were identified: Eimeria perforans, E. flavescens, E. piriformis, E. exigua, E. media, E. magna, E. coecicola, E. stiedai, E. roobroucki, E. intestinalis. Intensity of infection in young individuals was higher than in adults. Intensity was highest in winter but, as there are no young rabbits in winter, in young individuals it was higher in spring and autumn than in summer. Intensities were higher in the northern rather than in southern localities. Ranking of prevalence was remarkably stable, in contrast to the variability of the parasitic load. The equilibrium between congeneric species of rabbit coccidia (stable prevalence rank, variable parasitic load) is thought to be probably the consequence of the opportunistic feeding habits of rabbits.     

Helminths of the wild rabbit (Oryctolagus cuniculus) in Macaronesia

Two hundred and four rabbits from 8 Macaronesian islands (Pico, San Jorge, San Miguel, Terceira, and Flores from Azores Archipelago; Tenerife and Alegranza from Canary Islands; and Madeira from Madeira Archipelago) were examined for helminth parasites between 1995 and 2000. Three species of cestodes, Taenia pisiformis (larvae), Andrya cuniculi, and Mosgovoyia ctenoides, and 5 species of nematodes, Trichuris leporis, Graphidium strigosum, Trichostrongylus retortaeformis, Passalurus ambiguus, and Dermatoxys hispaniensis, were identified. Only 3 species (M. ctenoides, T. retortaeformis, and P. ambiguus) were regularly distributed over the 3 archipelagos. Taenia pisiformis was not collected in Madeira, nor was A. cuniculi in the Azores and G. strigosum in the Canary Islands. Trichuris leporis and D. hispaniensis were only found in Madeira. Significant differences in the general prevalence of the nematodes G. strigosum and T. retortaeformis were detected between Azores and Madeira. The prevalence of T. retortaeformis differs significantly between the Azores and the Canaries and that of P. ambiguus was higher in Madeira than in Azores and Canaries. The helminth richness found in the wild rabbit in these Macaronesian archipelagos was very low compared with the Palearctic helminth fauna of this host. The wild rabbit was introduced from the Iberian Peninsula into different Macaronesian islands. Helminths introduced with Oryctolagus cuniculus into these islands also are commonly found in Iberian wild rabbits, which are excellent colonizers, as demonstrated in this study.     

Cryptosporidium cuniculus in the rabbit (Oryctolagus cuniculus)

Cryptosporidium cuniculus was identified by light and electron microscopy in two apparently healthy rabbits. Organisms were firmly attached at the brush borders of intestinal epithelial cells. Cellular alterations were minimal, consisting of elongation and shortening of microvilli adjacent to the attachment sites of organisms. Various developmental stages of cryptosporidium were identified by electron microscopy.     

Polymorphism of the serum proteins of wild pigs

One hunderd and ninety five wild pigs from two different regions of Poland were investigated for transferrin, amylase and ceruloplasmin polymorphism. A new transferrin phenotype Tf PB was detected. This phenotype differed from Tf AB in the electrophoretic mobility of the more anodal transferrin. Tf P is assumed to be the product of a new allele Tf P at the Tf locus. Two amylase phenotypes Am 1–2 and Am 2 were observed. The Am 1 allele was absent from the pigs in the Poznan region. Only one ceruloplasmin phenotype, Cp B, was found.     

Inheritance of the equine Tf F3 allele

The inheritance of the equine Tf F3 allele was examined in 39 parent-offspring combinations. For 26 of the cases the allele inherited by the offspring from the heterozygous parent could be determined. The proportion of individuals that inherited the F3 variant compared to the alternative allele was exactly 1:1. In five cases the parental phenotype was identical to that of the offspring. For the remaining eight cases the parent was homozygous for the F3 allele and all offspring had the F3 allele. The results were consistent with Mendelian inheritance.     

Patterns of parasite aggregation in the wild European rabbit (Oryctolagus cuniculus)

Understanding the factors controlling the distribution of parasites within their host population is fundamental to the wider understanding of parasite epidemiology and ecology. To explore changes in parasite aggregation, Taylor's power law was used to examine the distributions of five gut helminths of the wild rabbit. Aggregation was found to be a dynamic process that varied with year, season, host sex, age class, and myxomatosis. Yearly and seasonal changes are thought, in the main, to be the result of variations in weather conditions acting upon infectious stages (or intermediate hosts). Evidence in support of this was the comparatively low degree of fluctuation in the aggregation of the pinworm, Passalurus ambiguus, as the infectious stage of this parasite is likely to be less susceptible to environmental variation. Host age had a marked effect on the level of aggregation of all parasites, but this effect varied between parasite species. P. ambiguus, Trichostrongylus retortaeformis and Cittotaenia denticulata aggregation were lower in adult than juvenile rabbits whilst Graphidium strigosum and Mosgovoyia pectinata aggregation tended to increase with age. Host immunity is thought to be responsible for these differences. Differences in aggregation for different parasites were also seen when the rabbit population was split into males and females. Myxomatosis had a marked effect on helminth distribution with substantially less aggregation in rabbits showing clinical signs of the disease.     

Electrophoretic variants of serum transferrin in wild pig populations of Japan

Variants of serum transferrin in Japanese wild pig, Sus scrofa leucomystax, and Ryukyu wild pig, S.s. riukiuanus, of Japan were investigated by using starch gel electrophoresis. Five phenotypes, TfB, BC, C, CX and X, were observed, of which two, TfCX and X, are new variants. Comparison of gene frequency estimates which were calculated for each population showed remarkable geographic differences among several populations of these two subspecies.     

Patterns of differentiation among wild rabbit populations Oryctolagus cuniculus L. in arid and semiarid ecosystems of north-eastern Australia

Feral rabbit populations in Australia have generally been managed using localized control procedures. While these procedures may result in local extinctions, persistence of populations will depend on the probability of recolonization. Genetic markers developed using temperature gradient gel electrophoresis (TGGE) combined with heteroduplex analysis (HA) of mitochondrial DNA (mtDNA) were used to characterize the degree of subdivision and extent of gene flow within and among rabbit populations distributed over large distances (up to 1000 km) in southern Queensland (QLD) and north-west New South Wales (NSW), Australia. TGGE analyses revealed significant heterogeneity in mtDNA control region haplotype frequencies. From heterogeneity χ² tests, it was evident that the differentiation observed was largely attributable to five sites which were located in the semiarid eastern region, whereas haplotype frequencies were homogeneous throughout the arid western region. These results suggest that there are independent population systems within the study area. The extent of gene flow among local populations within each system is related to the spatial configuration of acceptable habitat patches and the persistence of the populations is determined by the probability of recolonization following local extinction. These data suggest that to provide better overall control of rabbit populations, different management strategies may be necessary in arid and semiarid ecosystems. In arid south-west QLD and north-west NSW, where extensive gene flow occurs over large distances, rabbit populations should be managed at a regional level. In semiarid eastern QLD, where gene flow is restricted and populations are more isolated, localized control procedures may provide effective short-term relief. These results indicate that in nonequilibrium systems with patchy distribution of individuals, the interpretation of migration rate from estimates of gene flow obtained using existing genetic models must include an understanding of the spatial and temporal scales over which population processes operate.     

Fine-scale genetic structuring in a natural population of European wild rabbits (Oryctolagus cuniculus)

The genetic structure of a free-living tagged population of European wild rabbits (Oryctolagus cuniculus) was investigated for two consecutive years (1990 and 1991) using 10 polymorphic microsatellite loci. A specific social behaviour, the formation of stable breeding groups, influenced the genetic structure of the population. These breeding groups were shown to constitute genetically differentiated units with low levels of gene flow between them. The average relatedness among members of a social group was higher than within the population as a whole. As a result of female philopatry coupled with male-biased natal dispersal, the relatedness of females was higher than that of males, both within social groups and in the whole population. Furthermore, the average relatedness of females within groups was twice the relatedness of females between groups. This study reveals marked fine-scale, intrapopulation genetic structure, which is attributable to the social behaviour of the European wild rabbit.     

Seasonal changes in condition, reproduction and fecundity in the wild European rabbit (Oryctolagus cuniculus)

A total of 1248 rabbits ( Oryctolagus amiculus ) were shot on farmland in Cambridgeshire, UK over a period of three years. This provided pooled estimates of changes in reproductive and body condition and of fecundity during the annual cycle. Both males and females showed a significant annual cycle in reproductive condition as indicated by changes in the size of the gonads and accessory glands of reproduction. No females were pregnant during October, November and December, but males with active spermatogenesis were found during every month of the year. The distribution of pregnancies through the year showed that the reproductive season varied greatly between individuals. Peak fecundity occurred during April, May and June. On average, each female conceived 23.9 and suckled 17.2 young per breeding season. Proportionately more young died during the early stages of the reproductive season. The body weight of adult males, but not of females, varied seasonally. Body condition (kidney fat index) in adults was maximal at the start of the breeding season and minimal at the end.     

Two new common alleles of erythrocyte adenosine deaminase (ADA) in pigs

New adenosine deaminase variants ADA C and ADA D were found by means of agarose gel electrophoresis in pig erythrocytes. Family data supported the hypothesis that these are controlled by codominant alleles ADAC and ADAD. The ADAC allele was present in Large White (q = 0.076), Landrace (q = 0.037) and their crosses with other breeds. The ADAD allele was present in Duroc (q = 0.067) and its crosses. Allele frequencies for six pig breeds are given.