Toad

About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.

Effect of hypobaric hypoxia on spermatogenesis, Leydig cells and delta 5-3 beta-hydroxysteroid dehydrogenase activity in toad.

Abstract: The effect of different grades of hypobaric hypoxia for 48 hours was studied on spermatogenesis, Leydig cells and delta 5-3 beta-hydroxysteroid dehydrogenase activity in toad (Bufo melanostictus). Maximum inhibition of testicular activity was noted in 7,315 m exposed animals. The impairment of testicular function at high altitude is possibly due to inhibition of gonadotrophin secretion.

Bufo regularis, a twenty-chromosome toad.

Abstract: In applying short-term tissue culture methods as described by Beckert & Doyle (1967) to a study of Anuran karyotypes, the diploid number of chromosomes for Bufo regularis has been determined to be twenty. Six male Bufo, collected at Stoney Athi, 20 miles along Mombasa Road from Nairobi, were identified as Bufo regularis regularis Reuss by James Ashe, the Curator of Herpetology for the National Museum, Nairobi, Kenya. According to Webb (1966) this species is widely distributed throughout Africa south of the Sahara and is particularly common in regions with a high annual rainfall. Poynton (1964) extends the range upward to the Nile delta. Goin & Goin (1962) listed the diploid number for B. regularis as twenty-two chromosomes. This is in agreement with the observation by Manna & Bhunya (1966) that the diploid chromosome number for almost all reported Bufo species has not deviated from that of twenty-two chromosomes. Sanders & Cross (1963), who stated that the males of B. houstonensis had a chromosome constitution of twenty-one, and King (1907), who reported B. lentiginosus with a diploid number of twenty-four, took exception to this chromosome number pattern for Bufo. A pictorial analysis of a typical metaphase spread from the male B. regularis regularis Reuss (Fig. 1) indicated that it too was an exception to this pattern. Our results graphically show that B. regularis regularis Reuss has a •diploid number of twenty, four metacentric and six submetacentric pairs. The four metacentric pairs are two, six, seven and eight. The six submetacentric pairs are one, three, four, five, nine and ten. The most unique characteristic of this karyotype is a double achromatic region found •on the fifth pair of chromosomes. Here, close to the kinetochore, a secondary constriction is found on both arms. Single achromatic regions have been reported in other investigations with Bufo (Ullerich, 1966; Beckert & Doyle, 1967) and tend to encourage their use as markers within the karyotype. It has been suggested (Poynton, 1964) that a revision of the nomenclature is needed in •order to clarify the taxonomic position of six distinctive forms of toads that have been referred to as B. regularis to subspecies thereof. Since Goin & Goin (1962) listed all the chromosomes as being metacentric, in addition to having a different diploid number, it is possible that their sample was taken from one other than B. regularis regularis Reuss, possibly from the subgroup composed of garmani, rangeri or pardalis, which have been reported (Poynton, 1964) as being more closely associated to one another than to B. regularis regularis Reuss. An extension of this study analysing the possible karyotypic differences within the -B. regularis toads should contribute evidence to assist in their classification.

An Inhibitor of Oxytocin from the Urinary Bladder of the Toad, Bufo marinus

Abstract: A PREVIOUS investigation has shown that the isolated bladder of the toad, B. marinus, releases an inhibitor of oxytocin into the bathing Ringer's solution1. More recently a similar inhibitor has been invoked to explain the inhibition of the effects of vasopressin and of adenosine-3′, 5′-monophosphate on the toad bladder2. In the former investigation it was shown that inhibitor could be obtained by gently stirring isolated toad bladders in a modified Ringer's solution, and that the inhibitor so obtained was not readily dialysable. In the investigation reported here the previous results were confirmed; however, it was found that, following heat-treatment of the inhibitor solution, the inhibitor became dialysable. We report a modified preparation of the inhibitor based on this finding.