[
Methods Enzymol,
1994]
The nematode Caenorhabditis elegans is an excellent genetic system for dissecting protein function. Beginning with the pioneering work of Brenner numerous mutations have been generated and characterized phenotypically. Ease of culture, transparency, and small size, (fewer than 1000 nongonadal nuclei), have allowed the determination of a complete cell lineage map by direct observation of living nematodes. Colocalizatioin of genetic and physical loci is made possible by an extensive C. elegans genome map. The ability to identify genes corresponding to particular mutations has ad significantly with the development of methods for transformation of mutants with wild-type genes. The ability to introduce mutations into specific genes is now becoming possible by Tc1 transposon insertion of excision. A comprehensive volume describing all aspects of nematode biology is an excellent resource for anyone studying C. elegans, from novice to expert. In addition, The Worm Breeder's Gazette, published quarterly by the Caenorhabditis Genetics Center (CGC, University of Minnesota, St. Paul, MN), contains short research articles and technical notes contributed by members of the nematode community and represents a unique mechanism for keeping abreast of the latest techniques and the most recent results from other laboratories. The CGC, supported by the NIH National Center for Research Resources, also maintains a large collection of normal and mutant strains for distribution on request.
[
Trop Med Parasitol,
1987]
Simulium sanctipauli s.l. and S. yahense are common and widespread in the rain-forest zone of Liberia, but differ with regard to their biting densities and contribution to the transmission of Onchocerca volvulus. Although, in a study area on the St. Pauli River, S. sanctipauli s.l. (presumably S. soubrense in the sense of Post) was the predominant ma-biting species (74.3% of 30,855 females examined), S. yahense was shown to be the important vector. While 1000 biting females of S. yahense carried 96 3rd stage larvae indistinguishable from O. volvulus, only 14 were found per 1000 females of S. sanctipauli s.l. Of the parous females (3135 S. sanctipauli s.l./1621 S. yahense) 23.8/39.9% harboured 1st and/or 2nd stage filarial larvae and 1.9/9.4% 3rd stage larvae of O. volvulus. Animal filariae of unknown origin, indicative of zoophily, were very common in S. sanctipauli s.l. (13.8%) but practically absent from S. yahense (0.5%). In spite of its poorer vectorial performance S. sanctipauli s.l. cannot be neglected as a vector because it may occur in high biting densities and contribute considerably to the transmission, in particular in the vicinity of the St. Paul River. The interplay of two vector species, which develop in different types of water-courses explains the overall high endemicity of onchocerciasis in the study area.
[
Glycobiology,
2006]
Analysis of protein glycosylation within the nematode Caenorhabditis elegans has revealed an abundant and unreported set of core chitobiose modifications (CCM) to N-linked glycans. With hydrazine release an array of glycomers and isobars were detected with hexose extensions on the 3- and 3,6-positions of the penultimate and reducing terminus, respectively. A full complement of structures includes a range of glycomers posessing a Galss(1-4)Fuc disaccharide at the 3- and 6-positions of the protein-linked GlcNAc. Importantly, enzymatic (PNGase F/A) release failed to liberate many of these extended structures from reduced and alkylated peptides and, as a consequence, such profiles were markedly deficient in a representation of the worm glycome. Moreover, the 3-linked Galss(1-4)Fuc moiety was notably resistant to a range of commercial galactosidases. For identification the fragments were spectrum-matched with synthetic products and library standards using sequential mass spectrometry (MS(n)). A disaccharide observed at the 3-position of penultimate GlcNAc, indicating a Hex-Fuc branch on some structures, was not further characterized due to low ion abundance in MS(n). Additionally, a Hex-Hex-Fuc trisaccharide on the 6-position of proximal GlcNAc was also distinguished on select glycomers. Similar branch extensions on 6-linked core fucosyl residues have recently been reported among other invertebrates. Natural methylation and numerous isobars complement the glycome, which totals well over 100 individual structures. Complex glycans were detected at lower abundance, indicating glucosaminyltransferase (GnT)-I and GnT-II activity. A range of phosphorylcholine (PC) substituted complex glycans was also confirmed following a signature two-stage loss of PC during MS(n) analysis, although the precursor ion was not observed in the mass profiles. In a similar manner numerous other minor glycans may be present but unobserved in hydrazine release profiles dominated by fucosylated structures. All CCM structures, including multiple isomers, were determined without chromatography by gas-phase disassembly, (MS(n)), in Paul and linear ion trap instruments.