Probes and Point Mutations on the Web

Abstract

Dorit Rotenberg (University of Wisconsin-Madison, USA) was fascinated to see crystalline structures within the gut of rhabditids in culture when crystal violet was used to inhibit bacterial contamination. Have others encountered the phenomenon? Indeed they have! David Bird (North Carolina State University at Raleigh, USA) submitted A.F.Bird et al. Observations on crystalloid bodies in the pseudocoelom of Eutobrilus heptapapillatus. J. Nematol. 23, 39–47, 1991 [function unknown]. Michal Brzeski (Instytut Warzywnictwa, Poland) had seen crystals large enough to fill the entire gut lumen in most specimens of Enchodelis feeding on green moss. (M.W. Brzeski, Enchodelus repis new species and comments on Enchodelis laevisThorne, 1939 and Enchodelis microdoroides Baqri & Jairajpuri, 1974 (Nematoda:Dorylaimoidea) from Korea. Fundam Appl Nematol 15, 319–326, 1992.) He did not think they represented waste material as the worms have a functional anus. However, Orville G. Marti, Jr (University of Georgia, USA) thought those in the intestine of Noctuidonema, an ectoparasite of moths which has an imperforate anus, might be ‘an alternative to the usual method of waste elimination’. Jay Burr (Simon Fraser University, Canada) described crystalline haemoglobin found in the eye of mature adult female Mermis nigrescens ‘the only example of naturally crystalline hemoglobin [but with] the same dichroic spectrum as artificial crystals of vertebrate hemoglobins ... its unique function is to cast a shadow on a photoreceptor and thus provide mature females with the ability to discriminate the direction of light during phototaxis ...[it] appears to have been selected ... because of its strong light-absorbing property, rather than its oxygen-bearing ability.’ (A.H.J. Burr and C.P.F. Babinszki. Scanning motion, ocellar morphology and orientation mechanisms in the phototaxis of the nematode M. nigrescens. J. Compar. Physiol. A. 167, 257–268, 1990.) Sarah Rosloski (University of Guelph, Canada) had read that nematodes use extracellular freezing to protect themselves from freezing. She wondered if crystals might be caused by the release of nucleating substances into the lumen of the intestine, but David Wharton (University of Otago, New Zealand) thought this unlikely. ‘Most nematodes seem to rely on inoculative freezing, ie. ice from the surrounding medium penetrating through a body opening and initiating the freezing of the body contents.’ The antarctic nematode Panagrolaimus davidi can survive extensive intracellular freezing, and he suspects the ability to survive intracellular ice formation is common among nematodes which survive freezing. Jihua Wu (Chinese Academy of Sciences, Wuhan, Hubei), while not sure if they were the same thing as crystals, said ‘crystalloids’ occur in some freshwater genera (Monhystera, Ironus, Tobrilus and Tripyla), perhaps acting as a detoxification system by preventing harmful accumulation of metal sulphides (L.J. Jacobs and J. Heyns, An ecological strategy in the genus Monhystera – an hypothesis. Rev. Nematol. 13, 109–111, 1990). Michal Brzeski agreed with the distinction: crystalloids occur in the body cavity, large crystals in the gut.