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Journal articles on the topic 'African clawed toad'

Author: Grafiati

Published: 4 June 2021

Last updated: 2 February 2022

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1

Walsh, P. T., J. R. Downie, and P. Monaghan. "Plasticity of the duration of metamorphosis in the African clawed toad." Journal of Zoology 274, no. 2 (February 2008): 143–49. http://dx.doi.org/10.1111/j.1469-7998.2007.00367.x.

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2

Balls, Michael. "LYMPHOSARCOMA IN THE SOUTH AFRICAN CLAWED TOAD, XENOPUS LAEVIS: A VIRUS TUMOR*." Annals of the New York Academy of Sciences 126, no. 1 (December 16, 2006): 256–73. http://dx.doi.org/10.1111/j.1749-6632.1965.tb14279.x.

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3

Grant, Philip, Richard H. Clothier, Rachel O. Johnson, and Laurens N. Ruben. "In situ lymphocyte apoptosis in larval xenopus laevis, the South African clawed toad." Developmental & Comparative Immunology 22, no. 4 (July 1998): 449–55. http://dx.doi.org/10.1016/s0145-305x(97)00057-8.

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4

Furlong, Stephen T., Merle K. Heidemann, and Stephen C. Bromley. "Fine structure of the forelimb regenerate of the african clawed toad,xenopus laevis." Anatomical Record 211, no. 4 (April 1985): 444–49. http://dx.doi.org/10.1002/ar.1092110411.

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5

Ruben, L. N., K. M. Barr, R. H. Clothier, C. Nobis, and M. Balls. "T-Lymphocyte regulation of humoral immunity in Xenopus laevis , the South African clawed toad." Developmental & Comparative Immunology 9, no. 4 (1985): 811–18. http://dx.doi.org/10.1016/0145-305x(85)90047-3.

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6

Dumpert, Klaus. "Embryotoxic effects of environmental chemicals: Tests with the South African clawed toad (Xenopus laevis)." Ecotoxicology and Environmental Safety 13, no. 3 (June 1987): 324–38. http://dx.doi.org/10.1016/0147-6513(87)90031-5.

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7

Simmonds, Mark. "The fynbos and the frogs." Oryx 19, no. 2 (April 1985): 104–8. http://dx.doi.org/10.1017/s0030605300019815.

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The fynbos of the South African Cape is renowned for its high number of endemic plants and animals, many of which are under threat. Much effort and money are being spent to secure their future. Amphibians may be especially vulnerable due to land drainage, and amongst those facing this and other threats is the Cape clawed toad Xenopus gilli for which a conservation programme has been developed.

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8

Ruben, L. N., R. H. Clothier, G. L. Murphy, J. D. Marshall, R. Lee, T. Pham, C. Nobis, and S. Shiigi. "Thyroid function and immune reactivity during metamorphosis in Xenopus laevis, the South African clawed toad." General and Comparative Endocrinology 76, no. 1 (October 1989): 128–38. http://dx.doi.org/10.1016/0016-6480(89)90039-7.

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9

Clothier, Richard H., Laurens N. Ruben, Rachel O. Johnson, Kate Parker, Mika Sovak, Lisa Greenhalgh, Eng E. Ooi, and Michael Balls. "Neuroimmunomodulation: Neuroendocrine Regulation of Immunity: The Effects of Noradrenaline inXenopus Laevis, the South African Clawed Toad." International Journal of Neuroscience 62, no. 1-2 (January 1991): 123–40. http://dx.doi.org/10.3109/00207459108999766.

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10

Vosloo, A. "The effect of copper pollution on cutaneous gas exchange in the African clawed toad, Xenopus laevis." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 124 (August 1999): S146—S147. http://dx.doi.org/10.1016/s1095-6433(99)90578-0.

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11

Harris, P. D., and R. C. Tinsley. "The biology ofGyrdicotylus gallieni(Gyrodactylidea), an unusual viviparous monogenean from the African clawed toad,Xenopus laevis." Journal of Zoology 212, no. 2 (June 1987): 325–46. http://dx.doi.org/10.1111/j.1469-7998.1987.tb05993.x.

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12

Dumpert, Klaus. "Tests with the South African clawed toad () for detecting chemical causes of the decrease of amphibians." Chemosphere 15, no. 6 (January 1986): 807–11. http://dx.doi.org/10.1016/0045-6535(86)90048-2.

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13

Tuinhof, R., A. González, W. J. A. J. Smeets, and E. W. Roubos. "Neuropeptide Y in the developing and adult brain of the South African clawed toad Xenopus laevis." Journal of Chemical Neuroanatomy 7, no. 4 (October 1994): 271–83. http://dx.doi.org/10.1016/0891-0618(94)90018-3.

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14

SOLGONICK, RODNEY M., MICHAEL E. MORAN, JERRY HEDRICK, and GEORGE W. DRACH. "Effects of High-Energy Shock Waves on Rapidly Proliferating Cells: African Clawed Toad (Xenopus laevis) Zygote Model." Journal of Endourology 7, no. 5 (October 1993): 371–73. http://dx.doi.org/10.1089/end.1993.7.371.

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15

Ruben, Laurens N., Adam R. Goodman, Rachel O. Johnson, Johnan A. R. Kaleeba, and Richard H. Clothier. "The development of peripheral tnp-tolerance and suppressor function in Xenopus laevis, the South African clawed toad." Developmental & Comparative Immunology 19, no. 5 (September 1995): 405–15. http://dx.doi.org/10.1016/0145-305x(95)00020-t.

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16

Claas, Barbara, and Jeffrey Dean. "Prey-capture in the African clawed toad (Xenopus laevis): comparison of turning to visual and lateral line stimuli." Journal of Comparative Physiology A 192, no. 10 (June 15, 2006): 1021–36. http://dx.doi.org/10.1007/s00359-006-0137-2.

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17

Ubbels, Geertje A., Willem Berendsen, Sonja Kerkvliet, and Jenny Narraway. "Fertilization and development of eggs of the South African clawed toad, Xenopus laevis, on sounding rockets in space." Advances in Space Research 12, no. 1 (January 1992): 181–94. http://dx.doi.org/10.1016/0273-1177(92)90282-3.

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18

Tinsley, R. C. "A new species of Xenopus (Anura: Pipidae) from the highlands of Ethiopia." Amphibia-Reptilia 16, no. 4 (1995): 375–88. http://dx.doi.org/10.1163/156853895x00451.

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AbstractA new species of African clawed toad is described from the Bale Mountains region in southern Ethiopia. A series of small field samples indicate a maximum body length for females of about 50 mm. The new species is a 3-clawed Xenopus, distinguished by a rounded snout with relatively small eyes, a dark brown dorsal colouration lacking large spots or patches (which are common elsewhere in the genus), the absence of both a subocular tentacle and a metatarsal tubercle, and a small number of lateral line plaques (18 or 19 transverse plaques between eye and vent). The new species occurs in a region noted for the high proportion of endemic taxa in its fauna and flora; it occurs sympatrically with the single previously-known Ethiopian Xenofius, X. clivii, at around 2600 m asl., but is easily distinguished from this 4-clawed species. The new species has a chromosome number of 2n = 36; a series of biochemical and genetic studie indicate that it is most closely related to X. laevis and X. gilli and that it is relatively distant from the three species which are its nearest geographical neighbours, X. clivii, X. borealis and X. muelleri.

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19

Nera, M. Sherleen, Gretchen Vanderbeek, Rachel O. Johnson, Laurens N. Ruben, and Richard H. Clothier. "Phosphatidylserine expression on apoptotic lymphocytes of Xenopus laevis, the South African clawed toad, as a signal for macrophage recognition." Developmental & Comparative Immunology 24, no. 6-7 (September 2000): 641–52. http://dx.doi.org/10.1016/s0145-305x(00)00020-3.

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20

CANCELA, M. LEONOR, MATTHEW K. WILLIAMSON, and PAUL A. PRICE. "Amino-acid sequence of bone Gla protein from the African clawed toad Xenopus laevis and the fish Sparus aurata1." International Journal of Peptide and Protein Research 46, no. 5 (January 12, 2009): 419–23. http://dx.doi.org/10.1111/j.1399-3011.1995.tb01076.x.

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21

Bjerregaard, Henning F. "Electrophysiological Measurements of a Toad Renal Epithelial Cell Line (A6) as an Assay for Predicting Ocular Eye Irritancy." Alternatives to Laboratory Animals 20, no. 2 (April 1992): 218–21. http://dx.doi.org/10.1177/026119299202000206.

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An established epithelial cell line (A6) from a South African clawed toad (Xenopus laevis) kidney was used as a model for the corneal epithelium of the eye in order to determine ocular irritancy. When grown on Millipore filter inserts, A6 cells form a monolayer epithelium of high electrical resistance and generate a trans-epithelial potential difference. These two easily-measured electrophysiological endpoints showed a dose-related decrease after exposure for 24 hours to seven selected chemicals of different ocular irritancy potential. It was demonstrated that both trans-epithelial resistance and potential ranked closely with in vivo eye irritancy data and correlated well (r = 0.96) with loss of trans-epithelial impermeability of Madin-Darby canine kidney (MDCK) cells, detected by use of a fluorescein leakage assay.

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22

CANCELA, M. L., M. K. WILLIAMSON, and P. A. PRICE. "ChemInform Abstract: Amino-Acid Sequence of Bone Gla Protein from the African Clawed Toad Xenopus laevis and the Fish Sparus aurata." ChemInform 27, no. 9 (August 12, 2010): no. http://dx.doi.org/10.1002/chin.199609239.

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23

Kamali, D. D., L. N. Ruben, and M. T. Gregg. "The development of inducer and effector immune suppressor cell function in Xenopus laevis, the South African clawed toad: the effect of metamorphosis." Cell Differentiation 18, no. 4 (June 1986): 225–31. http://dx.doi.org/10.1016/0045-6039(86)90054-0.

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24

Gekle, Michael, and Stefan Silbernagl. "Basolateral uptake and tubular metabolism of L-citrulline in the isolated-perfused non-filtering kidney of the African clawed toad (Xenopus laevis)." Pfl�gers Archiv European Journal of Physiology 419, no. 5 (November 1991): 492–98. http://dx.doi.org/10.1007/bf00370794.

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25

H. Bartel, B. Minnich, I. Margreiter, and A. Lametschwandtner. "Vascular Regression In Gill Filters of Tadpoles of Xenopus Laevis Daudin: A Qualitative and Quantitative Sem Study on Vascular Corrosion Casts." Microscopy and Microanalysis 5, S2 (August 1999): 1188–89. http://dx.doi.org/10.1017/s1431927600019267.

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During metamorphosis amphibian tadpoles regress gills, tail and other larval structures. Thus gills are a good model to study how a highly complex three-dimensional vascular network regresses and finally disappears. Presently, only the microvascularization of external gills of larvae of Hynobiusdunni(2) and Litoria ewingi(3) is examined. The present study analyzes the spatio-temporal changes which the gill 3D-vascular network undergoes during metamorphosis using SEM of microvascular corrosion castings and a newly developed 3D-morphometry system (4, 5).Vascular casts of gills of tadpoles of the South African Clawed Toad, Xenopus laevis Daudin of stages 57 to 62 (6) were analyzed by SEM. Stereopaired images (tilting angle: 6 degrees) grabbed with a slow scan frame grabber (Orion 4.27) from the SEMs photo-display were imported into a 3Dmorphometry system (6) to measure vessel diameters, interbranching distances, branching angles and branching orders of filter row venules. This study reports the changes in the branching orders only.

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26

Fibla, Pablo, José M. Serrano, Franco Cruz-Jofré, Alejandra A. Fabres, Francisco Ramírez, Paola A. Sáez, Katherin E. Otálora, and Marco A. Méndez. "Evidence of predation on the Helmeted water toad Calyptocephalella gayi (Duméril & Bibron, 1841) by the invasive African clawed frog Xenopus laevis (Daudin 1802)." Gayana (Concepción) 84, no. 1 (June 2020): 64–67. http://dx.doi.org/10.4067/s0717-65382020000100064.

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27

Ruben, Laurens N., Richard H. Clothier, and Michael Balls. "Murine and human interleukin 2 can substitute for the thymus in immune responses to TNP-Ficoll in Xenopus laevis, the South African clawed toad." Cellular Immunology 93, no. 1 (June 1985): 229–33. http://dx.doi.org/10.1016/0008-8749(85)90403-4.

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28

Lametschwandtner, Alois, and Bernd Minnich. "Microvascular anatomy of ovary and oviduct in the adult African Clawed Toad ( Xenopus laevis DAUDIN, 1802)–Histomorphology and scanning electron microscopy of vascular corrosion casts." Anatomia, Histologia, Embryologia 49, no. 6 (May 24, 2020): 742–48. http://dx.doi.org/10.1111/ahe.12569.

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29

Highet, Ann B., and Laurens N. Ruben. "Corticosteroid regulation of IL-1 production may be responsible for deficient immune suppressor function during the metamorphosis of Xenopus laevis, the South African clawed toad." Immunopharmacology 13, no. 2 (April 1987): 149–55. http://dx.doi.org/10.1016/0162-3109(87)90052-x.

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30

RUBEN, L. "Recombinant DNA produced human IL-2, injected in vivo, will substitute for carrier priming of helper function in the South African clawed toad, Xenopus laevis." Immunology Letters 13, no. 5 (October 15, 1986): 227–30. http://dx.doi.org/10.1016/0165-2478(86)90106-9.

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31

A., Lametschwandtner, Minnich B., Margreiter I., Sommer R., and T. Stollinger. "The 3D-Architecture of the Blood Vascular System of the Ventral Tail Fin in Tadpoles of Xenopus Laevis Daudin: Intravital Microscope Observations and Scanning Electron Microscopy of Vascular Corrosion Casts." Microscopy and Microanalysis 6, S2 (August 2000): 558–59. http://dx.doi.org/10.1017/s1431927600035285.

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AbstractHemodynamics and 3D- architecture of the vascular network of the ventral tail fin of tadpoles of the South African Clawed Toad, Xenopus laevis Daudin were studied by intravital video microscopy (IVM) (stage 56) and vascular corrosion casts (VCCs)(stage 58). IVM enabled a detailed study of the circulation in segmental arteries, segmental venules and interposed capillaries. SEM of VCCs and 3-D morphometry allowed exact measurements of vessel diameters.Anuran tadpoles are good models to study blood vessel growth (=angiogenesis) (1-3) as well as blood vessel regression which occurs physiologically when tadpoles loose larval specific organs such as gills and tail during metamorphosis (4,5). The translucent ventral tail fin enables in-vivo observations of the living circulation by intravital light microscopy (1,2) and allows correlations between vessel fine structure and dynamics of blood flow under various conditions (2).This study focuses on the 3D-architecture of the blood vascular system in the ventral tail fin of tadpoles of Xenopus laevis Daudin in stage 58, i.e. at the begin of metamorphic climax.

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32

Lametschwandtner, A., U. Lametschwandtner, H. Bartel, C. Radner, and B. Minnich. "Microvascular Anatomy of Extrahepatic Bile Ducts in Adult South African Clawed Toad, Xenopus laevis Daudin: Scanning Electron Microscopy of Vascular Corrosion Casts and Correlative Light Microscopy." Microscopy and Microanalysis 15, S2 (July 2009): 986–87. http://dx.doi.org/10.1017/s1431927609093970.

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33

Lametschwandtner, A., M. Hoell, U. Lametschwandtner, and B. Minnich. "Larval to Adult Microvascular Anatomy of the Stomach of the South African Clawed Toad, Xenopus laevis Daudin: A Scanning Electron Microscope Study of Vascular Corrosion Casts." Microscopy and Microanalysis 12, S02 (July 31, 2006): 258–59. http://dx.doi.org/10.1017/s1431927606066359.

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34

van den Hurk, M. J. J., D. T. W. M. Ouwens, W. J. J. M. Scheenen, V. Limburg, H. Gellekink, M. Bai, E. W. Roubos, and B. G. Jenks. "Expression and Characterization of the Extracellular Ca2+-Sensing Receptor in Melanotrope Cells of Xenopus laevis." Endocrinology 144, no. 6 (June 1, 2003): 2524–33. http://dx.doi.org/10.1210/en.2003-0014.

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Abstract The extracellular Ca2+-sensing receptor (CaR) is expressed in many different organs in various species, ranging from mammals to fish. In some of these organs, this G protein-coupled receptor is involved in the control of systemic Ca2+ homeostasis, whereas in other organs its role is unclear (e.g. in the pituitary gland). We have characterized the CaR in the neuroendocrine melanotrope cell of the intermediate pituitary lobe of the South African clawed toad Xenopus laevis. First, the presence of CaR mRNA was demonstrated by RT-PCR and in situ hybridization. Then it was shown that activation of the CaR by an elevated extracellular Ca2+ concentration and different CaR-activators, including l-phenylalanine and spermine, stimulates both Ca2+ oscillations and secretion from the melanotrope. Furthermore, it was revealed that activation of the receptor stimulates Ca2+ oscillations through opening of voltage-operated Ca2+ channels in the plasma membrane of the melanotropes. Finally, it was shown that the CaR activator l-phenylalanine could induce the biosynthesis of proopiomelanocortin in the intermediate lobe. Thus, in this study it is demonstrated that the CaR is present and functional in a defined cell type of the pituitary gland, the amphibian melanotrope cell.

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35

Humphries, P., S. E. H. Russell, P. McWilliam, S. McQuaid, C. Pearson, and M. M. Humphries. "Observations on the structure of two human 7SK pseudogenes and on homologous transcripts in vertebrate species." Biochemical Journal 245, no. 1 (July 1, 1987): 281–84. http://dx.doi.org/10.1042/bj2450281.

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A comparison of the sequence of two human 7SK RNA pseudogenes, covering approx. 190 and 240 base-pairs of the structural gene, is presented. Both repeated elements are flanked by direct repeats and begin at the 5′ end of the gene. Each terminates approx. 90 base-pairs short of the 3′ end, the latter representing a continuous sequence and the former carrying an internal deletion of about 40 base-pairs, this region being flanked in the progenitor gene by short repeated sequences. Southern blotting using a human 7SK pseudogene probe illuminated a series of multiple restriction fragments in mammalian genomes, with generally fewer fragments in the genomes of birds and reptiles and a single reactive fragment in DNA from terrapin (Pseudemys scripta elegans) and Xenopus laevis (South African clawed toad). In the latter case this fragment was only detectable on long exposure under the hybridization stringencies employed. 7SK transcripts were readily detectable in all mammalian, avian, reptilian and amphibian species analysed, although the gene appeared to be expressed at rather low levels in the ovaries of Xenopus laevis, possibly accounting for its failure to have become dispersed via ‘retroposition’ in this species.

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36

Nomura, K., T. Tajima, H. Nomura, H. Shiraishi, M. Uchida, and K. Yamana. "Cell to cell adhesion systems in Xenopus laevis, the South African clawed toad II: Monoclonal antibody against a novel Ca2+-dependent cell—cell adhesion glycoprotein on amphibian cells." Cell Differentiation 23, no. 3 (April 1988): 207–12. http://dx.doi.org/10.1016/0045-6039(88)90073-5.

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37

Krattenmacher, R., R. Voigt, M. Heinz, and W. Clauss. "Electrolyte transport through a cation-selective ion channel in large intestinal enterocytes of Xenopus laevis." Journal of Experimental Biology 155, no. 1 (January 1, 1991): 275–90. http://dx.doi.org/10.1242/jeb.155.1.275.

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Electrogenic ion transport through the colon epithelium of the African clawed toad (Xenopus laevis) was investigated with electrophysiological methods in vitro. Interest was focused on a previously described phenomenon, that removal of Ca2+ from the mucosal Ringer's solution increases electrogenic sodium absorption. Our results clearly show that Ca2+ removal reveals an apical ion channel that is not a specific Na+ channel, but a non-selective cation channel with an ‘apparent’ ion selectivity of the order K+ greater than Na+ = Rb+ greater than Cs+ greater than Li+. This Ca2(+)-sensitive current increased linearly with the mucosal pH, and could be inhibited by other divalent cations (Mg2+, Ba2+) and the organic ion channel blockers quinidine and verapamil. The mucosal Ca2+ concentration that induced a half-maximal inhibition of the Ca2(+)-sensitive current was about 1 mumol l-1 and was independent of the mucosal pH. Owing to the high Ca2+ sensitivity, a regulation of the channel conductivity by extracellular Ca2+ is ruled out. It is concluded that this channel, which is almost identical to similar channels found in amphibian skin and bladder, acts as a pathway for cation absorbing or secreting processes. Possibly the binding of extracellular Ca2+ is related to selectivity changes of the Ca2(+)-sensitive ion channel.

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38

Tangphokhanon, W., H. Bartel, U. Lametschwandtner, C. Radner, S. Tholo, B. Minnich, and A. Lametschwandtner. "Microvascular Pattern Formation in the Lungs of the Adult African Clawed Toad, Xenopus laevis Daudin as Revealed by Scanning Electron Microscopy of Vascular Corrosion Casts and Correlative Light Microscopy." Microscopy and Microanalysis 16, S2 (July 2010): 870–71. http://dx.doi.org/10.1017/s1431927610054140.

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39

Gekle, Michael, and Stefan Silbernagl. "On leaking into the lumen, amino acids cross the tubule cells. Secretion of l-citrulline in the isolated-perfused non-filtering kidney of the African clawed toad (Xenopus laevis)." Pfl�gers Archiv European Journal of Physiology 419, no. 5 (November 1991): 499–503. http://dx.doi.org/10.1007/bf00370795.

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40

Lametschwandtner, A., H. Bartel, C. Radner, and B. Minnich. "Histomorphology and microvasculature of extrahepatic bile ducts, extrapancreatic ducts and choledocho-pancreatic duct in the adult African Clawed Toad, Xenopus laevis: Histomorphology and scanning electron microscopy of microvascular corrosion casts." Transactions of the Royal Society of South Africa 71, no. 1 (September 17, 2015): 7–16. http://dx.doi.org/10.1080/0035919x.2015.1078263.

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41

Mokhatla, Mohlamatsane, John Measey, and Ben Smit. "The role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern African anurans of different habitat specialisation." PeerJ 7 (October 22, 2019): e7885. http://dx.doi.org/10.7717/peerj.7885.

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Temperature and water availability are two of the most important variables affecting all aspects of an anuran’s key physiological processes such as body temperature (Tb), evaporative water loss (EWL) and standard metabolic rate (SMR). Since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (VPD), sex and body mass (Mb). However, a limited number of studies have tested the generality of these results across a wide range of ecologically relevant ambient temperatures (Ta), while taking habitat use into account. Thus, the aim of this study was to investigate the role of Ta on Tb, whole-animal EWL and whole-animal SMR in three wild caught African anuran species with different ecological specialisations: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis). Experiments were conducted at a range of test temperatures (5–35 °C, at 5 °C increments). We found that VPD better predicted rates of EWL than Ta in two of the three species considered. Moreover, we found that Tb, whole-animal EWL and whole-animal SMR increased with increasing Ta, while Tb increased with increasing Mb in A. delalandii and S. capensis but not in X. laevis. Whole-animal SMR increased with increasing Mb in S. capensis only. We did not find any significant effect of VPD, Mb or sex on whole-animal EWL within species. Lastly, Mb did not influence Tb, whole-animal SMR and EWL in the principally aquatic X. laevis. These results suggest that Mb may not have the same effect on key physiological variables, and that the influence of Mb may also depend on the species ecological specialisation. Thus, the generality of Mb as an important factor should be taken in the context of both physiology and species habitat specialisation.

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42

Ruben, Laurens N., Richard H. Clothier, and Michael Balls. "Cancer Resistance in Amphibians." Alternatives to Laboratory Animals 35, no. 5 (October 2007): 463–70. http://dx.doi.org/10.1177/026119290703500514.

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While spontaneous tumours may occasionally develop in inbred and isogenic strains of Xenopus laevis, the South African clawed toad, they are extremely rare in natural and laboratory populations. Only two amphibian neoplasms, the renal adenocarcinoma of Rana pipiens and the lymphosarcoma of Xenopus laevis, have been extensively explored. Amphibians are resistant to the development of neo-plasia, even following exposure to “direct-acting” chemical carcinogens such as N-methyl- N-nitrosourea, that are highly lymphotoxic, thus diminishing immune reactivity. Regenerative capacity in adults, and a dramatic metamorphosis which remodels much of the larval body to produce the adult form, are unique to amphibian vertebrates, and the control mechanisms involved may protect against cancer. For example, naturally rising corticosteroid titres during metamorphosis will impair some T-cell functions, and the removal of T-regulatory (suppressor) functions inhibits the induction of altered-self tolerance. Altered-self tolerance is not as effectively induced in adult Xenopus laevis as in mammals, so cancer cells with new antigenicity are more likely be rejected in amphibians. Amphibian immunocytes tend to undergo apoptosis readily in vitro, and, unlike mammalian immunocytes, undergo apoptosis without entering the cell cycle. Cells not in the cell cycle that die from nuclear damage (apoptosis), will have no opportunity to express genetic instability leading to cell transformation. We suggest that all these factors, rather than any one of them, may reduce susceptibility to cancer in amphibians.

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43

Dean, Jeffrey, and Barbara Claas. "African clawed toads (Xenopus laevis) sense the distance of lateral line stimuli." Journal of Comparative Physiology A 200, no. 7 (April 30, 2014): 657–67. http://dx.doi.org/10.1007/s00359-014-0911-5.

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Brausch, John M., Mike Wages, Randi D. Shannahan, Gad Perry, Todd A. Anderson, Jonathan D. Maul, Brian Mulhearn, and Philip N. Smith. "Surface water mitigates the anti-metamorphic effects of perchlorate in New Mexico spadefoot toads (Spea multiplicata) and African clawed frogs (Xenopus laevis)." Chemosphere 78, no. 3 (January 2010): 280–85. http://dx.doi.org/10.1016/j.chemosphere.2009.10.049.

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Moriah, Kristin. "On the Record: Sissieretta Jones and Black Feminist Recording Praxes." Performance Matters 6, no. 2 (March 16, 2021): 26–42. http://dx.doi.org/10.7202/1075797ar.

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In this article, I examine how Sissieretta Jones (frequently described as America’s first Black superstar, among other superlatives) strategically leveraged her European performance reviews in order to increase her listenership and wages in the United States. Jones toured Europe for the first (and only) time from February until November in 1895. According to clippings that she provided to African American newspapers, the singer performed at the renowned Winter Garden in Berlin for three months. Sissieretta Jones also claimed that she performed for Wilhelm II, the last German Emperor and King of Prussia, at his palace and was subsequently presented with an elaborate diamond brooch for her performance. Afterward, the singer told the African American newspaper the Indianapolis Freeman that she would like to live in Europe permanently. Her biographers frequently cite the success of this trip and its symbolic importance for African Americans. And yet, evidence of these events in the archives of major German newspapers is elusive and contradictory at best, if it exists at all. Nevertheless, after the much-hyped tour, her career would take many twists and turns. Sissieretta Jones eventually performed in venues like Carnegie Hall and Madison Square Garden. She was the highest-paid Black female performer of the nineteenth century and a role model for future generations of Black performers.

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Vansina, Jan. "It Never Happened: Kinguri's Exodus and its Consequences." History in Africa 25 (1998): 387–403. http://dx.doi.org/10.2307/3172195.

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The later precolonial history of a vast area in west central Africa between the Kwango and the Lubilash rivers starts with—and is dated by—the tradition of exodus of Kinguri and his companions from the heartland of the Lunda commonwealth. For the last two decades, however, several scholars have claimed that this tradition is merely a later addition to the older body of the traditions told by a dozen or so different peoples in west central Africa. Yet so far no one has examined where and when and how the Kinguri exodus tradition could have grafted itself onto the traditions of so many peoples over such a vast area. If true, this claim also requires a radical revision of the accepted history of western Lunda expansion. To examine the claim and its consequences is the aim of this article, which begins with the earliest written report of the Kinguri's exodus story.

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Arsan, Andrew Kerim. "Roots and Routes: The Paths of Lebanese Migration to French West Africa." Chronos 22 (April 7, 2019): 107–38. http://dx.doi.org/10.31377/chr.v22i0.451.

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We have no way of knowing when the first migrant from present-day Lebanon arrived in West Africa. Some amongst the Lebanese of Dakar still clung in the 1960s to tales ofa man, known only by his first name — 'Isa — who had landed in Senegal a century earlier (Cruise O'Brien 1975: 98). Others told ofa group of young men — Maronite Christians from the craggy escarpments of Mount Lebanon — who had found their way to West Africa some time between 1876 and 1880 (Winder 1962:30()). The Lebanese journalist 'Abdallah Hushaimah, travelling through the region in the 1930s, met in Nigeria one Elias al-Khuri, who claimed to have arrived in the colony in 1890 (Hushaimah 1931:332). The Dutch scholar Laurens van der Laan, combing in the late 1960s through old newspapers in the reading rooms of Fourah Bay College in Freetown, found the first mention of the Lebanese in the Creole press of Sierra Leone in 1895 (van der Laan 1975: l).

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Hallinger, Malek J., Anja Taubert, and Carlos Hermosilla. "Endoparasites infecting exotic captive amphibian pet and zoo animals (Anura, Caudata) in Germany." Parasitology Research 119, no. 11 (September 22, 2020): 3659–73. http://dx.doi.org/10.1007/s00436-020-06876-0.

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Abstract Alongside exotic reptiles, amphibians, such as toads, frogs, salamanders, and newts, are nowadays considered popular pets worldwide. As reported for other exotic pet animals, amphibians are known to harbor numerous gastrointestinal parasites. Nonetheless, very little data are available on captive amphibian parasitic diseases. In this study, we applied direct saline fecal smears (DSFS) to examine in total 161 stool samples from 41 different amphibian species belonging to the orders Anura and Caudata. In addition, carbolfuchsin-smear (CFS) staining (n = 74 samples) was used to detect amphibian Cryptosporidium oocysts. Also, complete dissections of deceased amphibians (n = 107) were performed to specify parasite infections and to address parasite-associated pathogenicity. Overall, examined amphibian fecal samples contained 12 different parasite taxa. The order Rhabditida with the species Rhabdias spp. and Strongyloides spp. were the most prevalent nematode species (19.3%), followed by flagellated protozoans (8.7%), Amphibiocapillaria spp./Neocapillaria spp. (7.5%), Oswaldocruzia spp. (4.3%), Blastocystis spp. (3.1%), Cosmocerca spp. (3.1%), oxyurids (Pharyngonoidae) (3.1%), spirurids (1.2%), un-sporulated coccidian oocysts (0.6%), Tritrichomonas spp. (0.6%), Karotomorpha spp. (0.6%), and Cryptosporidium spp. (0.6%). One CFS-stained fecal sample (1.4%) was positive for Cryptosporidium oocysts. Within dissected amphibians, 31 (48.4%) of the anurans and 11 (26.2%) of the salamanders were infected with gastrointestinal parasites. One cutaneous Pseudocapillaroides xenopi infection was diagnosed in an adult African clawed frog (Xenopus laevis). Etiologically, 17 (15.9%) of them died due to severe parasitic and/or bacterial infections (e.g., Chryseobacterium indologenes, Citrobacter freudii, Sphingobacterium multivorum, Klebsiella pneumoniae). High prevalence and pathological findings of several clinical amphibian parasitoses call for more detailed investigation on gastrointestinal parasite-derived molecular mechanisms associated with detrimental lesions or even death.

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Warbrick, Colin, and Zeray W. Yihdego. "II. Ethiopia's Military Action Against the Union of Islamic Courts and Others in Somalia: Some Legal Implications." International and Comparative Law Quarterly 56, no. 3 (July 2007): 666–76. http://dx.doi.org/10.1093/iclq/lei188.

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Somalia has been without government since 1991. A transitional government was established in 2004 under the presidency of Abdullahi Yusuf, with the backing of the United Nations, the African Union (AU), the Arab League and the Inter-governmental Agency for Development (IGAD). The Government sat in Baidoa in southern Somalia from June 2005 until December 2006. In June 2006 the Union of Islamic Courts (UIC) took control of much of southern and central Somalia, including the capital, Mogadishu, but not Puntland and Somaliland. They declared and tried to establish an Islamic State. Somalis were told to comply with stringent Islamic rules or face harsh punishment. In the meantime, efforts to achieve national reconciliation were ongoing under the auspices of IGAD, though without much success. It was reported that on 20 July 2006 Ethiopian troops crossed into Somalia. Ethiopia only admitted to having military trainers to help the Somali Government (estimated to be 400 military personnel). On 21 July, the UIC declared a ‘holy war’ against Ethiopia. In September 2006 the Somali interim President survived an assassination attempt in Baidoa. On 25 October 2006 Ethiopia said that it was ‘technically at war’ with the Islamic Courts. After few days the UIC claimed to have ambushed and killed Ethiopian troops near the Ethiopian border.1

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Scherer, Warren J., and Susan B. Udin. "Chronic effects of NMDA and APV on tectal output in Xenopus laevis." Visual Neuroscience 6, no. 2 (February 1991): 185–92. http://dx.doi.org/10.1017/s0952523800010567.

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AbstractIn the South African clawed-toed frog Xenopus laevis, visual experience plays a crucial role in the formation of matching binocular maps in the tectum. The ipsilateral eye's projection, relayed through the crossed isthmotectal projection, displays marked plasticity in response to altered visual input during a critical period of development. This plasticity and the events responsible for the end of the critical period are mediated by N-methyl-D-aspartate (NMDA) receptor function. We have previously reported that chronic blockade of tectal NMDA receptors with the NMDA antagonist 5-amino-phosphonovaleric acid (APV) prevents plasticity of the crossed isthmotectal projection during the critical period, while chronic treatment with NMDA restores this plasticity after the end of the critical period. These results raise the question of whether the effects on plasticity are due to changes in electrical responsiveness of the treated tissue. In this study, we have quantitatively assessed the actions of APV and NMDA on certain aspects of tectal cell activity in Xenopus during and after the critical period by recording the output of the nucleus isthmi cells that are activated by the tectum after three weeks of treatment. We have found that chronic APV treatment does not alter tectal output, as indicated by the firing of isthmotectal axons, during the critical period and that chronic NMDA treatment increases tectal output in postcritical period Xenopus. Tectal output does not differ between normal Xenopus during and after the end of the critical period.These results indicate that the effect of APV on blocking isthmotectal plasticity is not due to a nonspecific inhibition of the segment of the retinotectal relay that activates the nucleus isthmi. The enhancement of tectal output in postcritical period Xenopus by chronic NMDA treatment may promote the effectiveness of NMDA in restoring isthmotectal plasticity after the end of the critical period, but the finding that tectal activity does not differ between normal Xenopus during and after the critical period implies that a reduction in tectal activity in not the cause of the loss of plasticity at the end of the critical period.

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