Worm Breeder's Gazette 14(3): 26 (June 1, 1996)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
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There is precious little in the literature regarding the regenerative ability of nematodes (Poinar, 1988). The received wisdom has been that the determinate cleavage in these pseudocoelomates precludes any possibility of epimorphic regeneration (K.A. Wright pers. comm., 1988). Although Filipjev (1921) stated that regeneration is "completely absent" in nematodes, other reports by Micoletzky and Kreis (1930) and Allgen (1959) present another picture which seemingly contradicts such a blanket generalization. Last year it was reported that a gastrotrich (undescribed species of Turbanella) of the genera Macrodasyidae, a primitive sister group of the Nematoda, restored epidermis with complete wound closure following transection; restructuring of Y organ and intestine; and caudal adhesive tubes forming anew (Manylov, 1995). This is the first report of regeneration in this group. In another recent paper from the former Soviet Union, Voronov and Panchin (1995a) report that a nematode, of the order Enoplida (E.brevis), has a process of gastrulation which contradicts the patterns of cleavage formerly ascribed to the Enoplida (Malakhov,1994). They observed that up to the sixteenth cell stage cleavage is usually (though this can vary) equal and synchronous, producing blastomeres of equal appearance; elsewhere they observe that the primordia which gives rise to all the endoderm can be derived from either the anterior or posterior at the two-cell stage (Voronov and Panchin,1995b). This variability, they offer, makes the Enoplida different from other nematodes studied. Malakhov believes that this variability "can even engender the idea that the cleavage among members of marine Enoplida is indeterminate, but this is not so." (p.166). However, the cleavage of the Enoplida may be indeterminate enough to allow for the regenerative phenomena recently witnessed in a gastrotrich. In sum, Enoplid cleavage patterns would appear to be similar to the more primitive patterns seen in the Macrodasyidae, which is consistent with the notion that equal cleavage is ancestral and determination of early blastomere fate derived (Baguna and Boyer,1990). Also, it should be remembered that in addition to the single species reported by Micoletzky and Kreis, all nine of the species which Allgen found evidence of regeneration were marine Enoplids. Allgen,C.A.(1959)Free living marine nematodes. Further Zool. Results Swed. Antarct. Exp. 1901-03 vol.5 no.2: 1-293. Baguna,J.,B.C.Boyer(1990)Descriptive and experimental embryology of the Turbellaria: Present knowledge, open questions and future trends. In Marthy, H.(ed), Experimental Embryology in Aquatic Plants and Animals. NATO ASI 195; 95-128. Filipjev,I.N.(1921)Free living nematodes in the vicinity of Sevastapol. (in Russian), Akad. Nauk SSSR. Trudy osob. zool. lab. ser 2 41: 351-614. Malakhov,V.V.(1994)Nematodes: Structure, Development, Classification and Phylogeny. Smithsonian Inst. Press. Manylov,O.G.(1995)Regeneration in Gastrotricha - I. Light microscopical observations on the regeneration in Turbanella sp. . Acta Zool. 76:1-6. Micoletzky,H.,H.A.Kreis(1930)Freilbende marine Nematoden von den sunda-Inseln. Dansk natur. Foren. Vid. medd. Bd 87: 243-339. Poinar,G.O.(1992)Immune responses and wound repair. In Diseases of Nematodes. vol 1, p.133-40, CRC Press, Boca Raton, Florida. Voronov,D.A.,Y.V.Panchin(1995a)The early-stage of the cleavage in the free-living marine nematode Enoplus brevis (Enoplida, Enoplidae) in the normal and experimental conditions. Zool. Zhurn. 74(6): 31-38. Voronov,D.A.,Y.V.Panchin(1995b)Gastrulation in the free-living marine nematode Enoplus brevis and the localization of endodermal material at the stage of 2 blastomeres in the nematodes of the order Enoplida. Zool. Zhurn. 74(10): 10-18.