Reproduction, development and growth of Akodon lindberghi (Hershkovitz, 1990) (Rodentia, Muridae, Sigmodontinae) raised in captivity

The reproduction, development and growth of Akodon lindberghi were studied in captivity. The colony was derived from animals captured in Simão Pereira, Minas Gerais state, which represents a new area of geographical distribution known for this species. Twelve males and twelve females were crossed, producing 144 young in 53 litters. Post-partum oestrus was observed and gestation length was estimated in 23 days. Litter size ranged from 1 to 4 with a mean of 2.72 (SD = 0.97, n = 53) and modal size of 3. Sexual dimorphism was neither present in body mass at birth nor at weaning. There was a significant negative correlation between litter size and mass at birth or weaning. Permanent emergence of adult external appearance occurred at 15 days. Puberty for males and females was 43 and 42 days, respectively, and the first fecundation event for two females was recorded at 47 and 54 days of age. The weight growth was described by fitting a Gompertz model. No significant difference was found in any parameter of growth curves for males and females. Measurements (head-body, tail, hind foot and internal and external ear lengths) obtained for adult individuals also did not reveal the presence of sexual dimorphism.

A reprodução, o crescimento e o desenvolvimento de Akodon lindberghi foram estudados em cativeiro. A colônia foi derivada de animais capturados em Simão Pereira, Minas Gerais, Brasil, localidade que representa uma nova área de distribuição geográfica conhecida para esta espécie. Doze machos e doze fêmeas foram acasalados, produzindo 144 filhotes em 53 ninhadas. Observou-se estro pós-parto e o período de gestação foi estimado em 23 dias. O tamanho médio da ninhada foi de 2,72 (SD = 0,97, n = 53), com amplitude de 1 a 4 e moda de 3 filhotes. Não houve dimorfismo sexual do peso dos filhotes ao nascimento e ao desmame. O tamanho da ninhada foi negativamente correlacionado com o peso ao nascimento e ao desmame. A emergência da aparência externa adulta (pêlos, dentes e olhos e orelhas abertos) ocorreu aos 15 dias. A puberdade em machos e fêmeas ocorreu aos 43 e 42 dias, respectivamente, e a primeira fecundação para duas fêmeas, aos 47 e 54 dias. O crescimento do peso foi descrito através do modelo de Gompertz. Não houve diferença significativa entre machos e fêmeas em nenhum parâmetro das curvas de crescimento, bem como nas medidas corporais (cabeça-corpo, cauda, pé posterior, e orelhas interna e externa) obtidas para animais adultos.

Reproduction, development and growth of Akodon lindberghi (Hershkovitz, 1990) (Rodentia, Muridae, Sigmodontinae) raised in captivity.

The reproduction, development and growth of Akodon lindberghi were studied in captivity. The colony was derived from animals captured in Simão Pereira, Minas Gerais state, which represents a new area of geographical distribution known for this species. Twelve males and twelve females were crossed, producing 144 young in 53 litters. Post-partum oestrus was observed and gestation length was estimated in 23 days. Litter size ranged from 1 to 4 with a mean of 2.72 (SD = 0.97, n = 53) and modal size of 3. Sexual dimorphism was neither present in body mass at birth nor at weaning. There was a significant negative correlation between litter size and mass at birth or weaning. Permanent emergence of adult external appearance occurred at 15 days. Puberty for males and females was 43 and 42 days, respectively, and the first fecundation event for two females was recorded at 47 and 54 days of age. The weight growth was described by fitting a Gompertz model. No significant difference was found in any parameter of growth curves for males and females. Measurements (head-body, tail, hind foot and internal and external ear lengths) obtained for adult individuals also did not reveal the presence of sexual dimorphism.

A reference map of Cucumis melo based on two recombinant inbred line populations.

A composite genetic melon map was generated based on two recombinant inbred line (RI) populations. By analyzing the segregation of 346 AFLPs, 113 IMAs and phenotypic characters on a RI population of 163 individuals derived from the cross Védrantais x PI 161375, a first map was constructed. About 20% of the molecular markers were skewed, and the residual heterozygosity was estimated at 4.43% which was not significantly different from the theoretical value of 4.2%. The genome distribution of molecular markers among the 12 linkage groups was not different from a random distribution with the exception of linkage group XII which was found significantly less populated. The genome distributions of IMAs and AFLPs were complementary. AFLPs were found mainly in the middle of each linkage group and sometimes clustered, whereas IMAs were found mainly at the end. A total of 318 molecular markers, mainly AFLP and IMA markers, were mapped on 63 RIs of the second population, Védrantais x PI 414723. Comparison of the maps enables one to conclude that AFLPs and IMAs of like molecular size, amplified with the same primer combination, correspond to the same genetic locus. Both maps were joined through 116 common markers comprising 106 comigrating AFLPs/IMAs, plus five SSRs and five phenotypic markers. The integrated melon map contained 668 loci issuing from the segregation of 1,093 molecular markers in the two RI populations. The composite map spanned 1,654 cM on 12 linkage groups which is the haploid number of chromosomes in melon. Thirty two known-function probes, i.e. known-function genes (9) and morphological traits (23), were included in this map. In addition, the composite map was anchored to previously published maps through SSRs, RFLPs and phenotypic characters.