Bat forelimbs are highly specialized for sustained flight, providing a unique model to explore the genetic programs that regulate vertebrate limb diversity. Hoxd9-13 genes are important regulators of stylopodium, zeugopodium, and autopodium development and thus evolutionary changes in their expression profiles and biochemical activities may contribute to divergent limb morphologies in vertebrates. We have isolated the genomic region that includes Hoxd12 and Hoxd13 from Carollia perspicillata, the short-tailed fruit bat. The bat Hoxd13 gene encodes a protein that shares 95% identity with human and mouse HOXD13. The expression pattern of bat Hoxd13 mRNA during limb development was compared with that of mouse. In bat and mouse hindlimbs, the expression patterns of Hoxd13 are relatively similar. However, although the forelimb Hoxd13 expression patterns in both organisms during early limb bud stages are similar, at later stages they diverge; the anterior expression boundary of bat Hoxd13 is posterior-shifted relative to the mouse. These findings, compared with the Hoxd13 expression profiles of other vertebrates, suggest that divergent Hoxd13 expression patterns may contribute to limb morphological variation.
Abstract
Improved methods have been developed for maintaining and breeding the neotropical short-tailed fruit bat, Carollia perspicillata, in an easily-reproduced, laboratory setting. Bipartite, all-metal cages have been designed which permit efficient, non-injurious handling of the animals. Also, a fruit-based liquid diet, which is simple and inexpensive to prepare, has been formulated from readily-available canned and powdered components. When efforts were initiated to breed wild-caught animals at 3-6 months after capture, this progressed slowly in most (but not all) cages. Breeding took place more rapidly when the bats had been in captivity for 11-24 months. Most females (122/144, 84.7%) then bred within 30 days of the introduction of a stud male, and the overall conception rate was 94.3% in those females which bred. This pattern of breeding activity, evidence that this bat is a spontaneous ovulator, and observed intervals between successive breeding periods (apparently representing much or all of non-pregnant cycles) in some individuals suggest that the cycle length in many of these bats probably falls between 20 and 30 days. Analysis of the breeding data also showed that certain patterns of breeding activity were frequently associated with a failure of females to establish ongoing pregnancies. Most laboratory-bred females (69/81) that were permitted to carry their pregnancies to term did so and successfully reared their young. The laboratory-reared young have generally exhibited excellent body condition, and many have proved to be fertile. The bats were found to exhibit a post-partum oestrus, which in nearly all cases (35/36) was fertile. The interval between the discovery of a new baby and the detection of a sperm-positive vaginal aspirate varied between 3-10 days, but most frequently was 3-6 days. Females which aborted non-term fetuses also had a post-partum oestrus with similar timing. These findings indicate that the short-tailed fruit bat, which is widely abundant in the lowland tropics of the New World, can be successfully maintained under controlled conditions, in cages of modest dimensions, for research purposes.
This photo, taken by Dorit Hockman of the University of Cambridge, took 20th place in Nikon's annual Small World Photomicrography Competition,
There are approximately 4,800 extant species of mammals that exhibit tremendous morphological, physiological, and developmental diversity. Yet embryonic development has been studied in only a few mammalian species. Among mammals, bats are second only to rodents with regard to species number and habitat range and are the most abundant mammals in undisturbed tropical regions. Bat development, though, remains relatively unstudied. Here, we describe and illustrate a staging series of embryonic development for the short-tailed fruit bat, Carollia perspicillata, based on embryos collected at timed intervals after captive matings. As Carollia can be readily maintained and propagated in captivity and is extremely abundant in the wild, it offers an attractive choice as a chiropteran model organism. This staging system provides a framework for studying Carollia embryogenesis and should prove useful as a guide for embryological studies of other bat species and for comparisons with other orders of mammals. Developmental Dynamics 233:721–738, 2005. © 2005 Wiley-Liss, Inc.
Improved methods have been developed for maintaining and breeding the neotropical short-tailed fruit bat, Carollia perspicillata, in an easily-reproduced, laboratory setting. Bipartite, all-metal cages have been designed which permit efficient, non-injurious handling of the animals. Also, a fruit-based liquid diet, which is simple and inexpensive to prepare, has been formulated from readily-available canned and powdered components. When efforts were initiated to breed wild-caught animals at 3-6 months after capture, this progressed slowly in most (but not all) cages. Breeding took place more rapidly when the bats had been in captivity for 11-24 months. Most females (122/144, 84.7%) then bred within 30 days of the introduction of a stud male, and the overall conception rate was 94.3% in those females which bred. This pattern of breeding activity, evidence that this bat is a spontaneous ovulator, and observed intervals between successive breeding periods (apparently representing much or all of non-pregnant cycles) in some individuals suggest that the cycle length in many of these bats probably falls between 20 and 30 days. Analysis of the breeding data also showed that certain patterns of breeding activity were frequently associated with a failure of females to establish ongoing pregnancies. Most laboratory-bred females (69/81) that were permitted to carry their pregnancies to term did so and successfully reared their young. The laboratory-reared young have generally exhibited excellent body condition, and many have proved to be fertile. The bats were found to exhibit a post-partum oestrus, which in nearly all cases (35/36) was fertile. The interval between the discovery of a new baby and the detection of a sperm-positive vaginal aspirate varied between 3-10 days, but most frequently was 3-6 days. Females which aborted non-term fetuses also had a post-partum oestrus with similar timing. These findings indicate that the short-tailed fruit bat, which is widely abundant in the lowland tropics of the New World, can be successfully maintained under controlled conditions, in cages of modest dimensions, for research purposes.
This photo, taken by Dorit Hockman of the University of Cambridge, took 20th place in Nikon's annual Small World Photomicrography Competition,
There are approximately 4,800 extant species of mammals that exhibit tremendous morphological, physiological, and developmental diversity. Yet embryonic development has been studied in only a few mammalian species. Among mammals, bats are second only to rodents with regard to species number and habitat range and are the most abundant mammals in undisturbed tropical regions. Bat development, though, remains relatively unstudied. Here, we describe and illustrate a staging series of embryonic development for the short-tailed fruit bat, Carollia perspicillata, based on embryos collected at timed intervals after captive matings. As Carollia can be readily maintained and propagated in captivity and is extremely abundant in the wild, it offers an attractive choice as a chiropteran model organism. This staging system provides a framework for studying Carollia embryogenesis and should prove useful as a guide for embryological studies of other bat species and for comparisons with other orders of mammals. Developmental Dynamics 233:721–738, 2005. © 2005 Wiley-Liss, Inc.
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