The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform

Marilyn B. Renfree - One of the best experts on this subject based on the ideXlab platform.

  • The effect of pregnant and oestrous females on male testosterone and behaviour in the tammar wallaby
    Hormones and Behavior, 2010
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    Tammar wallaby females (Macropus eugenii) are seasonally breeding marsupials with a post-partum oestrus after a highly synchronised birth period when testosterone concentrations rise in males. Chemical communication appears to be important for mating, as males show checking behaviour, sniffing the Urogenital Opening (UGO) and the pouch of females. This study investigates whether the presence of pregnant and oestrous females directly influences testosterone in males and if oestrous odours or secretion from the pouch or UGO are attractive. Concentrations of plasma testosterone were measured in males housed with pregnant and oestrous females during two consecutive cycles in the breeding season, and an artificially induced cycle in the non-breeding season. Males were also tested for their interest in swabs taken from the Urogenital Opening (UGO) or pouch of oestrous females. Testosterone increased sharply in males in the presence of pregnant and oestrous females during all cycles in both seasons, but there was no change when males were exposed to non-cycling females in lactational or seasonal diapause. Males had no preference for either oestrous or non-oestrous samples taken from the pouch or from the UGO from oestrous females. This study confirms that the increase in plasma testosterone in tammar males can be induced through the presence of pregnant and oestrous females, regardless of season and that the increase began when the females were in late-pregnancy. This confirms that the male's reproductive state is dependent on a signal from females and is not blocked through seasonal effects.

  • The olfactory system of the tammar wallaby is developed at birth and directs the neonate to its mother's pouch odours.
    Reproduction, 2009
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    : In kangaroos and wallabies at birth the highly altricial newborn young climbs unassisted from the Urogenital Opening to the teat. Negative geotropism is important for the initial climb to the pouch Opening, but nothing is known of the signals that then direct the neonate downwards to the teat. Here we show that the newborn tammar wallaby (Macropus eugenii) has the olfactory apparatus to detect smell. Both the main olfactory system and vomeronasal organ (VNO) are developed at the time of birth. Receptor cells of the main olfactory epithelium immunopositive for G(oalpha)-protein project to the three layered main olfactory bulb (MOB). The receptor epithelium of the VNO contains G-protein immunopositive cells and has olfactory knob-like structures. The VNO is connected to an area between the two MOBs. Next, using a functional test, we show that neonates can respond to odours from their mother's pouch. When neonatal young are presented with a choice of a pouch-odour-soaked swab or a saline swab, they choose the swab with their mother's pouch secretions significantly more often (P

Nanette Y. Schneider - One of the best experts on this subject based on the ideXlab platform.

  • The effect of pregnant and oestrous females on male testosterone and behaviour in the tammar wallaby
    Hormones and Behavior, 2010
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    Tammar wallaby females (Macropus eugenii) are seasonally breeding marsupials with a post-partum oestrus after a highly synchronised birth period when testosterone concentrations rise in males. Chemical communication appears to be important for mating, as males show checking behaviour, sniffing the Urogenital Opening (UGO) and the pouch of females. This study investigates whether the presence of pregnant and oestrous females directly influences testosterone in males and if oestrous odours or secretion from the pouch or UGO are attractive. Concentrations of plasma testosterone were measured in males housed with pregnant and oestrous females during two consecutive cycles in the breeding season, and an artificially induced cycle in the non-breeding season. Males were also tested for their interest in swabs taken from the Urogenital Opening (UGO) or pouch of oestrous females. Testosterone increased sharply in males in the presence of pregnant and oestrous females during all cycles in both seasons, but there was no change when males were exposed to non-cycling females in lactational or seasonal diapause. Males had no preference for either oestrous or non-oestrous samples taken from the pouch or from the UGO from oestrous females. This study confirms that the increase in plasma testosterone in tammar males can be induced through the presence of pregnant and oestrous females, regardless of season and that the increase began when the females were in late-pregnancy. This confirms that the male's reproductive state is dependent on a signal from females and is not blocked through seasonal effects.

  • The olfactory system of the tammar wallaby is developed at birth and directs the neonate to its mother's pouch odours.
    Reproduction, 2009
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    : In kangaroos and wallabies at birth the highly altricial newborn young climbs unassisted from the Urogenital Opening to the teat. Negative geotropism is important for the initial climb to the pouch Opening, but nothing is known of the signals that then direct the neonate downwards to the teat. Here we show that the newborn tammar wallaby (Macropus eugenii) has the olfactory apparatus to detect smell. Both the main olfactory system and vomeronasal organ (VNO) are developed at the time of birth. Receptor cells of the main olfactory epithelium immunopositive for G(oalpha)-protein project to the three layered main olfactory bulb (MOB). The receptor epithelium of the VNO contains G-protein immunopositive cells and has olfactory knob-like structures. The VNO is connected to an area between the two MOBs. Next, using a functional test, we show that neonates can respond to odours from their mother's pouch. When neonatal young are presented with a choice of a pouch-odour-soaked swab or a saline swab, they choose the swab with their mother's pouch secretions significantly more often (P

Yasunori Koya - One of the best experts on this subject based on the ideXlab platform.

  • role of the yellow spot around the Urogenital Opening of female mosquitofish gambusia affinis as a cue for copulation
    Zoological Science, 2008
    Co-Authors: Ichiro Kodama, Akira Yamanaka, Katsuhiko Endo, Yasunori Koya
    Abstract:

    Abstract Males of the viviparous teleost fish Gambusia affinis copulate with females by using a specialized anal fin, or gonopodium. When female G. affinis were placed in a shallow transparent tank which was then floated on the surface of a larger aquarium housing male G. affinis, the males frequently attempted to copulate with females housed in the smaller quarantine tank. This copulatory behavior in male G. affinis was only observed to be elicited by visual stimuli; female G. affinis have a yellow spot and black anal spots around their Urogenital Opening. To investigate the function of the yellow spot of the female, we examined male copulatory behavior directed towards artificial female models having a yellow, black, gray, or white spot in the genital region. Of the differently colored females tested, males spent a significantly longer time in the vicinity of the artificial model with a yellow spot. In addition, males attempted to copulate with the yellow-spotted female model more frequently than with t...

Geoff Shaw - One of the best experts on this subject based on the ideXlab platform.

  • The effect of pregnant and oestrous females on male testosterone and behaviour in the tammar wallaby
    Hormones and Behavior, 2010
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    Tammar wallaby females (Macropus eugenii) are seasonally breeding marsupials with a post-partum oestrus after a highly synchronised birth period when testosterone concentrations rise in males. Chemical communication appears to be important for mating, as males show checking behaviour, sniffing the Urogenital Opening (UGO) and the pouch of females. This study investigates whether the presence of pregnant and oestrous females directly influences testosterone in males and if oestrous odours or secretion from the pouch or UGO are attractive. Concentrations of plasma testosterone were measured in males housed with pregnant and oestrous females during two consecutive cycles in the breeding season, and an artificially induced cycle in the non-breeding season. Males were also tested for their interest in swabs taken from the Urogenital Opening (UGO) or pouch of oestrous females. Testosterone increased sharply in males in the presence of pregnant and oestrous females during all cycles in both seasons, but there was no change when males were exposed to non-cycling females in lactational or seasonal diapause. Males had no preference for either oestrous or non-oestrous samples taken from the pouch or from the UGO from oestrous females. This study confirms that the increase in plasma testosterone in tammar males can be induced through the presence of pregnant and oestrous females, regardless of season and that the increase began when the females were in late-pregnancy. This confirms that the male's reproductive state is dependent on a signal from females and is not blocked through seasonal effects.

  • The olfactory system of the tammar wallaby is developed at birth and directs the neonate to its mother's pouch odours.
    Reproduction, 2009
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    : In kangaroos and wallabies at birth the highly altricial newborn young climbs unassisted from the Urogenital Opening to the teat. Negative geotropism is important for the initial climb to the pouch Opening, but nothing is known of the signals that then direct the neonate downwards to the teat. Here we show that the newborn tammar wallaby (Macropus eugenii) has the olfactory apparatus to detect smell. Both the main olfactory system and vomeronasal organ (VNO) are developed at the time of birth. Receptor cells of the main olfactory epithelium immunopositive for G(oalpha)-protein project to the three layered main olfactory bulb (MOB). The receptor epithelium of the VNO contains G-protein immunopositive cells and has olfactory knob-like structures. The VNO is connected to an area between the two MOBs. Next, using a functional test, we show that neonates can respond to odours from their mother's pouch. When neonatal young are presented with a choice of a pouch-odour-soaked swab or a saline swab, they choose the swab with their mother's pouch secretions significantly more often (P

T. P. Fletcher - One of the best experts on this subject based on the ideXlab platform.

  • The effect of pregnant and oestrous females on male testosterone and behaviour in the tammar wallaby
    Hormones and Behavior, 2010
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    Tammar wallaby females (Macropus eugenii) are seasonally breeding marsupials with a post-partum oestrus after a highly synchronised birth period when testosterone concentrations rise in males. Chemical communication appears to be important for mating, as males show checking behaviour, sniffing the Urogenital Opening (UGO) and the pouch of females. This study investigates whether the presence of pregnant and oestrous females directly influences testosterone in males and if oestrous odours or secretion from the pouch or UGO are attractive. Concentrations of plasma testosterone were measured in males housed with pregnant and oestrous females during two consecutive cycles in the breeding season, and an artificially induced cycle in the non-breeding season. Males were also tested for their interest in swabs taken from the Urogenital Opening (UGO) or pouch of oestrous females. Testosterone increased sharply in males in the presence of pregnant and oestrous females during all cycles in both seasons, but there was no change when males were exposed to non-cycling females in lactational or seasonal diapause. Males had no preference for either oestrous or non-oestrous samples taken from the pouch or from the UGO from oestrous females. This study confirms that the increase in plasma testosterone in tammar males can be induced through the presence of pregnant and oestrous females, regardless of season and that the increase began when the females were in late-pregnancy. This confirms that the male's reproductive state is dependent on a signal from females and is not blocked through seasonal effects.

  • The olfactory system of the tammar wallaby is developed at birth and directs the neonate to its mother's pouch odours.
    Reproduction, 2009
    Co-Authors: Nanette Y. Schneider, T. P. Fletcher, Geoff Shaw, Marilyn B. Renfree
    Abstract:

    : In kangaroos and wallabies at birth the highly altricial newborn young climbs unassisted from the Urogenital Opening to the teat. Negative geotropism is important for the initial climb to the pouch Opening, but nothing is known of the signals that then direct the neonate downwards to the teat. Here we show that the newborn tammar wallaby (Macropus eugenii) has the olfactory apparatus to detect smell. Both the main olfactory system and vomeronasal organ (VNO) are developed at the time of birth. Receptor cells of the main olfactory epithelium immunopositive for G(oalpha)-protein project to the three layered main olfactory bulb (MOB). The receptor epithelium of the VNO contains G-protein immunopositive cells and has olfactory knob-like structures. The VNO is connected to an area between the two MOBs. Next, using a functional test, we show that neonates can respond to odours from their mother's pouch. When neonatal young are presented with a choice of a pouch-odour-soaked swab or a saline swab, they choose the swab with their mother's pouch secretions significantly more often (P