Abstract
This study investigates ovulation and egg deposition behaviors in the anuran Eleutherodactylus coqui from Puerto Rico in response to stimulation with gonadotropin and gonadotropin releasing hormones. Five hormones were tested by injection over a range of doses, including mammalian LHRH, avian LHRH, fish LHRH, D-Ala6, des-Gly10 ethylamide LHRH and hCG. We report a low level of ovulation and egg deposition in response to all hormones, with the most complete and consistent results from the non-natural D-Ala6, des-Gly10 ethylamide LHRH derivative. To confirm the viability of eggs produced in this manner we performed in vitro fertilization experiments that resulted in the development of normal frogs. Reproductive behaviors in E. coqui are apparently not controlled by a mammalian form of LHRH as reported in other common laboratory anuran species. D-Ala6, des-Gly10 ethylamide LHRH induces ovulation and deposition of mature and fertilizable eggs in E. coqui.
Highlights
Several amphibian species have been commonly used in studies of reproductive biology
All of the unmodified leutinizing hormone releasing hormones (LHRHs) induced some ovulatory activity in E. coqui, none was more effective compared to the others either in terms of percentage of animals that laid eggs or the numbers of eggs deposited
Previous work has indicated that a form indistinguishable from mammalian LHRH appears to control reproductive behaviors in Xenopus [18], and mammalian LHRH has been shown to induce ovulation in Rana catesbeiana and Rana temporaria [14,15]
Summary
Several amphibian species have been commonly used in studies of reproductive biology. Despite the large amount of information known regarding a few laboratory species (most notably Rana pipiens and Xenopus laevis), the reproductive biology of the majority of amphibian species remains poorly understood This is unfortunate as amphibians, and especially anurans, show the greatest diversity in reproductive strategies among all of the terrestrial vertebrates, including internal and external fertilization, terrestrial and aquatic breeding, development with a larval stage, direct external development, ovoviviparity, mass seasonal breeding, continuous breeding, and presence or absence of parental care. With over 700 described species, this is the largest vertebrate genus and as such is an excellent system for studies of comparative biology [1] As far as it is known, these species undergo direct development in terrestrial eggs (one species is known to be ovoviviparous [2]), and often exhibit parental care [3]. Many species of these frogs are territorial and continuous or nearly (page number not for citation purposes)
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