BackgroundSome organisms can survive extreme desiccation by entering into a state of suspended animation known as anhydrobiosis. Panagrolaimus superbus is a free-living anhydrobiotic nematode that can survive rapid environmental desiccation. The mechanisms that P. superbus uses to combat the potentially lethal effects of cellular dehydration may include the constitutive and inducible expression of protective molecules, along with behavioural and/or morphological adaptations that slow the rate of cellular water loss. In addition, inducible repair and revival programmes may also be required for successful rehydration and recovery from anhydrobiosis.ResultsTo identify constitutively expressed candidate anhydrobiotic genes we obtained 9,216 ESTs from an unstressed mixed stage population of P. superbus. We derived 4,009 unigenes from these ESTs. These unigene annotations and sequences can be accessed at http://www.nematodes.org/nembase4/species_info.php?species=PSC. We manually annotated a set of 187 constitutively expressed candidate anhydrobiotic genes from P. superbus. Notable among those is a putative lineage expansion of the lea (late embryogenesis abundant) gene family. The most abundantly expressed sequence was a member of the nematode specific sxp/ral-2 family that is highly expressed in parasitic nematodes and secreted onto the surface of the nematodes' cuticles. There were 2,059 novel unigenes (51.7% of the total), 149 of which are predicted to encode intrinsically disordered proteins lacking a fixed tertiary structure. One unigene may encode an exo-β-1,3-glucanase (GHF5 family), most similar to a sequence from Phytophthora infestans. GHF5 enzymes have been reported from several species of plant parasitic nematodes, with horizontal gene transfer (HGT) from bacteria proposed to explain their evolutionary origin. This P. superbus sequence represents another possible HGT event within the Nematoda. The expression of five of the 19 putative stress response genes tested was upregulated in response to desiccation. These were the antioxidants glutathione peroxidase, dj-1 and 1-Cys peroxiredoxin, an shsp sequence and an lea gene.ConclusionsP. superbus appears to utilise a strategy of combined constitutive and inducible gene expression in preparation for entry into anhydrobiosis. The apparent lineage expansion of lea genes, together with their constitutive and inducible expression, suggests that LEA3 proteins are important components of the anhydrobiotic protection repertoire of P. superbus.
Reed canarygrass (Phalaris arundinacea L.) is a cool‐season perennial with a circumglobal distribution in the northern hemisphere, native to Europe, Asia, and North America. Repeated introductions of European germplasm into North America have created confusion over the origins of reed canarygrass germplasm found in wetlands, pastures, and breeding programs. The objectives of this study were to identify sources of DNA marker variation among reed canarygrass cultivars from Europe and North America and between landraces and improved cultivars from North America. Analysis of 205 reed canarygrass plants from 15 cultivars based on 102 amplified fragment length polymorphic (AFLP) DNA markers revealed two groups of cultivars. One group consisted of three closely related but geographically diverse North American landraces that were completely separated from all other plants in only two dimensions of the AFLP incidence matrix. The complete discrimination of these plants from all European plants suggests their possible origin from native North American germplasm. These results were supported by chloroplast DNA sequence analysis, which additionally revealed separation of a potential Scandinavian cytoplasmic race from the continental European cytoplasmic race. This is the strongest evidence to date suggesting that native North American reed canarygrass germplasm has been preserved within cultivars of this species.
a positive ELISA for Lyme disease was found in up to 40% of patients with established SLE and also in other rheumatic diseases. However, specific serum antibodies to Borrelia were not confirmed by the more specific immunoblot technique.(ABSTRACT TRUNCATED AT 250 WORDS)
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