Clawed toad

There is some evidence for chemically mediated endocrine disruption in amphibians. The egg yolk protein, vitellogenin, is inducible in amphibians by exposure to DDT. " Males of the short clawed toad Xenopus laevis given 250 fig/g or 1 fig/g o,p -DDT for seven days have been shown to produce vitellogenin, although the induction was less than that achieved by treatment with 1 fig/g of either 17/1-oestradiol or diethylstilboestrol. Research has also shown that endocrine disrupting chemicals can alter sex ratios in wild populations of certain species PCB congeners and organochlorine compounds have been linked with male domination of sex ratios in polluted compared to unpolluted sites. ... 

Fig. 4.3 Morphogenesis during metamorphosis in Amphibia diagramatic sequence of MOS/AOS formation in African Clawed Toad (Xenopus). OP, olfactory placode PC, principal cavity and MC, mid-cavity (from Meyer and Jadhao, 1996).

The lateral diverticulum cells in semi-terrestrial species such as toads can still detect a wide range of amino acids, comparable to the properties of fish neuroepithelium. Both water-soluble and volatile odourants are discriminated by the olfactory neurones of the Clawed toad (Xenopus) (Iida and Kashiwayanagi, 1999). When single olfactory neurones were tested with acidic, neutral and basic amino acids, over 50% of the receptors gave some excitatory response. 

Balls, M. 1964. Benzpyrene-induced tumours in the clawed toad, Xenopus laevis. Experientia 20 143-145. 

Slooff, W. and Baerselman, R. Comparison of the nsefnlness of the Mexican axolotl (Ambystoma mexicanuni) and the clawed toad (Zenopus laevis) in toxicological bioassays, BuU. Environ. Contam. Toxicol., 24(3) 439-443, 1980. 

Amphibia embryo of clawed toad (Xenopus laevis)b 104 400 liver of newt (Triturus vulgaris and T. cristatus)e 106 about 30,000. 

Xenopus laevis, the South African clawed toad, is a frog, not a toad. It is often used as a model organism for the study of early vertebrate development. 

The administration of estrogen to the clawed toad Xenopus laevis causes the induction of a calcium-binding glycoprotein which is found in the... 

Some current limitations of RNAi should be mentioned in organisms such as Xmopus laevis (the African clawed toad) and Danio rerio (the zebrafish), RNAi has had limited success as a routine method, and only functions under certain circumstances. Here, the standard use of mor-pholinos (chemical modified antisense oli-gos) has routinely proven to be the method of choice, though more studies on RNAi are necessary to establish a routine use in cells and embryos of these vertebrates. 

In vitro studies with abdominal skin of Rana pipiens demonstrated that naphthalene inhibited sodium transport after exposure to 4.4mg/L for 30 min. Some data were available on biological effects of benzo[a]pyrene, 3-methylcholanthrene, and perylene to reptiles and amphibians. Implantation of 1.5 mg of benzo[a]pyrene crystals into the abdominal cavity of adult South African clawed toads (Xenopus laevis) produced lymphosarcomas in 11 of the 13 toads (85%) ter 86-288 days. Immature toads were more resistant with only 45% bearing lymphoid tumors of liver, kidney, spleen, or abdominal muscle 272-310 days after implantation of 1.5 mg of benzo[a]pyrene crystals in the dorsal lymph sac or abdominal cavity. Implantation of 3-methylcholanthrene crystals into X. laevis provokes development of lymphoid tumors similar to those occurring naturally in this species moreover, these... 

Xenopsin, XP an octapeptide from the skin of the African clawed toad, Xenopus laevis. The structure of XP Pyr-Gly-Lys-Arg-Pro-Trp-Ile-Leu-OH, is very similar to that of Neurotensin (see). Antiserum raised to the C-terminal region of neurotensin cross-reacts with XP. Neurotensin and XP both characteristically increase the hematocrit and induce cyanosis in anesthetized rats. XP therefore appears to be an amphibian counterpart of neurotensin. Other peptides im-... 

We have previously observed that prior section of the optic nerve greatly enhanced outgrowth of neurites from the explanted retina of Xenopus laevis, the African clawed toad (Agranoff et al., 1976). A similar finding was obtained with goldfish (Landreth Agranoff, in press). In this case, retinas are removed under sterile conditions and are cut into 600 pm wide ribbons. The retina is turned 90, and the process is repeated. The resultant full-thickness squares of retina are now set out in petri dishes on a suitable substratum, such as a collagen gel, or... 

Brown, D. D., and Littna, E. (1964). RNA synthesis during the development of Xenopus laevis, the South African Clawed Toad. J. Mol. Biol. 8, 669-687. 

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