Insights into the formation and diversification of a novel chiropteran wing membrane from embryonic development.

Background: Through the evolution of novel wing structures, bats (Order Chiroptera) became the only mammalian group to achieve powered flight. This achievement preceded the massive adaptive radiation of bats into diverse ecological niches. We investigate some of the developmental processes that underlie the origin and subsequent diversification of one of the novel membranes of the bat wing: the plagiopatagium, which connects the fore- and hind limb in all bat species.

Transcriptomic insights into the genetic basis of mammalian limb diversity.

Background: From bat wings to whale flippers, limb diversification has been crucial to the evolutionary success of mammals. We performed the first transcriptome-wide study of limb development in multiple species to explore the hypothesis that mammalian limb diversification has proceeded through the differential expression of conserved shared genes, rather than by major changes to limb patterning. Specifically, we investigated the manner in which the expression of shared genes has evolved within and among mammalian species.

The Relationship between Gene Network Structure and Expression Variation among Individuals and Species.

Variation among individuals is a prerequisite of evolution by natural selection. As such, identifying the origins of variation is a fundamental goal of biology. We investigated the link between gene interactions and variation in gene expression among individuals and species using the mammalian limb as a model system.

The evolution and development of mammalian flight.

Mammals have evolved a stunning diversity of limb morphologies (e.g., wings, flippers, hands, and paws) that allowed access to a wide range of habitats.

Early oogenesis in the short-tailed fruit bat Carollia perspicillata: transient germ cell cysts and noncanonical intercellular bridges.

The ovaries of early embryos (40 days post coitum/p.c.) of the bat Carollia perspicillata contain numerous germ-line cysts, which are composed of 10 to 12 sister germ cells (cystocytes).

Embryonic staging system for the Black Mastiff Bat, Molossus rufus (Molossidae), correlated with structure-function relationships in the adult.

An embryonic staging system for Molossus rufus (also widely known as Molossus ater) was devised using 17 reference specimens obtained during the postimplantation period of pregnancy from wild-caught, captive-bred females. This was done in part by comparing the embryos to a developmental staging system that had been created for another, relatively unrelated bat, Carollia perspicillata (family Phyllostomidae). Particular attention was paid to the development of species-specific features, such as wing and ear morphology, and these are discussed in light of the adaptive significance of these structures in the adult.

A second wave of Sonic hedgehog expression during the development of the bat limb.

Sonic hedgehog (Shh) plays an integral role in both the anterior-posterior (A-P) patterning and expansion of developing vertebrate limbs through a feedback loop involving Fgfs, Bmps, and Gremlin. In bat limbs A-P patterning and the size of the digital field are unique. The posterior digits of the forelimb are elongated and joined by tissue, whereas the thumb is short.

Regulatory divergence modifies limb length between mammals.

Natural selection acts on variation within populations, resulting in modified organ morphology, physiology, and ultimately the formation of new species. Although variation in orthologous proteins can contribute to these modifications, differences in DNA sequences regulating gene expression may be a primary source of variation. We replaced a limb-specific transcriptional enhancer of the mouse Prx1 locus with the orthologous sequence from a bat.

Polarized ovaries of the long-tongued bat, Glossophaga soricina: a novel model for studying ovarian development, folliculogenesis, and ovulation.

Glossophaga soricina is a spontaneously ovulating, monovular, polyestrous bat with a simplex uterus, exhibiting true menstruation. Studies conducted on reproductively active, captive-maintained animals established that G. soricina also has polarized ovaries, with the ovarian surface epithelium (OSE) restricted to the medial side of the ovary, and primordial follicles limited to an immediately adjacent zone.

Isolation, genomic structure and developmental expression of Fgf8 in the short-tailed fruit bat, Carollia perspicillata.

Fibroblast growth factor-8 (Fgf8) encodes a secreted protein which was initially identified as the factor responsible for androgen-dependant growth of mouse mammary carcinoma cells (Tanaka et al., 1992). Fgf8 has been subsequently implicated in the patterning and growth of the gastrulating embryo, paraxial mesoderm (somites), limbs, craniofacial tissues, central nervous system and other organ systems during the development of several vertebrate model animals.

Embryonic staging system for the short-tailed fruit bat, Carollia perspicillata, a model organism for the mammalian order Chiroptera, based upon timed pregnancies in captive-bred animals.

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.

Hoxd13 expression in the developing limbs of the short-tailed fruit bat, Carollia perspicillata.

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.