Tables for the normal development of Rana sylvatica

Pollister, Arthur W.; Moore, John A.

doi:10.1002/ar.1090680410

Cited by 92 publications

(28 citation statements)

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“…Although early development of túngara frogs closely resembled the developmental pattern of X. laevis, more advanced embryos greatly differed from X. laevis . The external morphology of advanced embryos of Engystomops resembled the morphology of Rana embryos (Pollister and Moore, 1937), with a major difference in pigmentation, as foam-nest embryos of túngara frogs lack dark surface pigment.…”

Section: Resultsmentioning

confidence: 87%

Embryogenesis and laboratory maintenance of the foam‐nesting túngara frogs, genus Engystomops (= Physalaemus)

Romero‐Carvajal

Sáenz-Ponce

Venegas-Ferrín

et al. 2009

Developmental Dynamics

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The vast majority of embryological research on amphibians focuses on just a single genus of frogs, Xenopus. To attain a more comprehensive understanding of amphibian development, experimentation on non-model frogs will be essential. Here, we report on the early development, rearing, and embryological analysis of tú ngara frogs (genus Engystomops, also called Physalaemus). The frogs Engystomops pustulosus, Engystomops coloradorum, and Engystomops randi construct floating foam-nests with small eggs. We define a table of 23 stages for the developmental period in the foam-nest. Embryos were immunostained against Lim1, neural, and somite-specific proteins and the expression pattern of RetinoBlastoma Binding Protein 6 (RBBP6) was analyzed by in situ hybridization. Due to their brief life-cycle, frogs belonging to the genus Engystomops are attractive for comparative and genetic studies of development.

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Section: Resultsmentioning

confidence: 87%

Embryogenesis and laboratory maintenance of the foam‐nesting túngara frogs, genus Engystomops (= Physalaemus)

Romero‐Carvajal

Sáenz-Ponce

Venegas-Ferrín

et al. 2009

Developmental Dynamics

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“…Whatever the mechanism, two expo-Ecological Aspects of Amphibian Metamorphosis Nonnormal distributions of competitive ability reflect selection for facultative metamorphosis. Henry M. Wilbur and James P. Collins case in amphibians (1,7,(20)(21)(22). Two experiments were designed to investigate variation in growth rates.…”

Section: Growth Mlodels For Larval Amphibiansmentioning

confidence: 99%

Ecological Aspects of Amphibian Metamorphosis

Wilbur

Collins

1973

Science

1,093

314

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A synthetic theory of the ecology of amphibian metamorphosis is founded on the observation that the large variation in length of larval period and body size at metamorphosis typical of a particular species of amphibian cannot be directly explained by differences in dates of hatching or egg sizes. It is proposed that as development proceeds, variation in exponential growth coefficients causes a trend from a normal distribution to a skewed distribution of body sizes. The degree of skewing increases and the median of the distribution decreases with increasing initial densities of populations. The relative advantages of the largest members of a cohort may arise from a variety of mechanisms including the production of growth inhibitors, interference competition, and size-selective feeding behavior. These mechanisms result in a nonnormal distribution of competitive ability, a possible source of the density-dependent competition coefficient found in systems with many species (1). In our model the ranges of body sizes and dates of metamorphosis are determined by a minimum body size that must be obtained and a maximum body size that will not be exceeded at metamorphosis. Between these two size thresholds the endocrinological initiation of metamorphosis is expected to be related to the recent growth history of the individual larva. Species that exploit uncertain environments will have a wide range of possible sizes at metamorphosis. Species exploiting relatively certain environments will have a narrower range. The evolution of neoteny and direct development logically follow from the application of these ideas to the ecological context of the evolution of amphibian life histories. Species that live in constant aquatic habitats surrounded by hostile environments (desert ponds, caves, high-altitude lakes) may evolve permanent larvae genetically incapable of metamorphosis. Other populations may evolve a facultative metamorphosis such that populations are a mixture of neotenes and terrestrial adults. Direct development results from selection to escape the competition, predation, and environmental uncertainty characteristic of some aquatic habitats and is usually accompanied by parental care. The relation between our ecological model and the physiological mechanisms that initiate metamorphosis can only be suggested and it remains an open problem for developmental biologists.

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“…Even under uniform environmental conditions the tadpoles arising from a given egg mass show considerable variation in their degree of development a t any given time (46,53). For this reason only tadpoles of approximately the same size and a t the same stage of development mere selected for treatment with the carcinogens and as controls.…”

Section: Methodsmentioning

confidence: 99%

“…The eggs thus obtained were raised in finger bowls, about 20 eggs in each, in t a p water a t room temperature. When the tadpoles were well established (three to four weelts of age) treatment with the carcinogen was begun.Even under uniform environmental conditions the tadpoles arising from a given egg mass show considerable variation in their degree of development a t any given time (46,53). For this reason only tadpoles of approximately the same size and a t the same stage of development mere selected for treatment with the carcinogens and as controls.…”

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confidence: 99%

The Effects of the Carcinogen, 2-Acetylaminofluorene, on Larval and Adult Frogs

McCallion¹

1954

Can. J. Zool.

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2-Acetylaminofluorene is a po\verful carcinogen capable of inducing a variety of benign and malignant neoplasms in several species of anirl~als ancl is required only in very small amounts for relatively short periods of time. I t is sorne\\rhat sol~rble ( 1 . 3 rllgm. per 100 cc.) in water. Frog taclpoles \\,ere raised in solutions of various strengths. Even dilute solutions proved to be highly toxic to these animals. In those animals that sur\;ived it was found that 2-acetylaminofluorene inhibits both total body growtll ancl rate of tail regeneration; that the tadpoles remninetl dark (melanophores clilatecl) even on a light backgro~rnd; that lesions of the liver developed resembling those described in mammals resulting from treatment with the same and other carcinogens. It is not certain that these lesions are neo,plastic, but they may be of the type that precede or accompany liver cell carclnonla. This carcinogen \\.as also fed to or injected into adult frogs. E\.en small amounts \\-ere toxic to them and only a small nunlber survivetl for Inore t-han a few days. In the survi\rors, after six to eight n:eel;s, lesions of thc liver, including necrosis and cirrhosis, appeared. No distinct rleoplasrns were produced.The present investigation represents a study of the effects of a ltnown carcinogenic substance upon both larval and adult frogs in an attempt to produce neoplasia in these animals. Materials and MethodsThe carcinogen used in this investigation was 2-acetylaminofluorene (Eastman I

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Tables for the normal development of Rana sylvatica

Cited by 92 publications

References 0 publications

Embryogenesis and laboratory maintenance of the foam‐nesting túngara frogs, genus Engystomops (= Physalaemus)

Embryogenesis and laboratory maintenance of the foam‐nesting túngara frogs, genus Engystomops (= Physalaemus)

Ecological Aspects of Amphibian Metamorphosis

The Effects of the Carcinogen, 2-Acetylaminofluorene, on Larval and Adult Frogs

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