Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season

The Libyan jird (Meriones libycus, 1823) is a wild desert rodent that is a seasonal breeder species adapted to breed when the environmental conditions can satisfy the energy and hydrous requirements of pregnant and nursing females to ensure that births occur at the most favorable time of the year. We assessed gene expression of testicular luteinizing hormone receptor (Lhcgr) correlated to testis activity. The expression of Lhcgr was evaluated using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR and the testis activity by a histological method in adult male Libyan jirds during the nonbreeding and breeding seasons. Our results showed that Lhcgr mRNA expression increased in autumn during the nonbreeding season and decreased in spring during the breeding season. This expression varied in contrast to testicular structure or function and plasma testosterone levels. These results help to elucidate this desert rodent’s seasonal sexual activity, which is correlated with central regulation.

Circulating inhibin and testosterone during sexual maturation and reproductive seasonality of captive male killer whales (Orcinus orca)

The present study aimed to investigate the reproductive biology of male killer whales. Changes in the concentrations of two circulating testicular hormones, inhibin and testosterone, were monitored during sexual maturation of two male Type 1 Eastern Northern Atlantic killer whales over a period of 20 years. The two killer whales grew rapidly at the pubertal stage and reached a plateau at the age of 23 and 20 years, respectively, after which growth slowed down. In the younger male, circulating inhibin was higher in the juvenile than in the pubertal and mature stages; whereas circulating testosterone exhibited the opposite trend. The pubertal period was estimated to last approximately 5 years, from 12 to 17 years of age. In the elder male, circulating testosterone was high from the onset of this study (12 years of age), when the animal also sired successfully for the first time. This finding shows that the male killer whale is possible to sire even if it is not socially matured, if there is opportunity for copulation. During the mature stage, both animals exhibited significantly higher circulating testosterone concentrations in spring compared to autumn and winter; whereas no seasonal change was observed for circulating inhibin. These results clearly demonstrate that the male killer whale is a seasonal breeder, even though it is fertile throughout the year. This is the first study to elucidate the inhibin concentration and secretory source in the male killer whale.

Immunolocalization of aromatase P450 in the epididymis of Podarcis sicula and Rattus rattus

The goal of this study was to evaluate P450 aromatase localization in the epididymis of two different vertebrates: the lizard Podarcis sicula, a seasonal breeder, and Rattus rattus, a continuous breeder. P450 aromatase is a key enzyme involved in the local control of spermatogenesis and steroidogenesis and we proved for the first time that this enzyme is represented in the epididymis of both P. sicula and R. rattus. In details, P450 aromatase was well represented in epithelial and myoid cells and in the connective tissue of P. sicula epididymis during the reproductive period; instead, during autumnal resumption this enzyme was absent in the connective tissue. During the non-reproductive period, P450 aromatase was localized only in myoid cells of P. sicula epididymis, whereas in R. rattus it was localized both in myoid cells and connective tissue. Our findings, the first on the epididymis aromatase localization in the vertebrates, suggest a possible role of P450 aromatase in the control of male genital tract function, particularly in sperm maturation.

Aspects of reproduction, and morphology of the penis, of Pseudantechinus woolleyae (Marsupialia : Dasyuridae)

Woolley’s Pseudantechinus, P. woolleyae, has remained virtually unstudied in the 30 years since its recognition in 1988 as a species distinct from P. macdonnellensis. It has a wide distribution in arid regions of Western Australia. What little is known of its biology comes largely from studies carried out over the years 1988–91 on one wild-caught female and her offspring, and a few specimens held in the collection of the Western Australian Museum. P. woolleyae is a seasonal breeder and young are born from late July to early October. They mature when ~7 months old. Both males and females are potentially capable of breeding in more than one year. Males have accessory erectile tissue that does not form an appendage on the penis.