Search

Debris-covered glaciers (DCGs) are glaciers whose ablation area is mostly covered by a continuous layer of debris, and are considered to be among the continental glacierized environments richest in life. DCG colonization by microorganisms, plants and animals, has been investigated in a few studies, while the meiofauna (metazoans smaller than 2 mm) of these environments has been neglected so far. In this study, we analyzed nematode and rotifer fauna on the two largest debris-covered glaciers of the Italian Alps: the Miage Glacier and the Belvedere Glacier. In total, we collected 38 debris samples on the glaciers in July and September 2009. All the rotifers we found belonged to the bdelloid Adineta vaga (Davis, 1873). Nematodes belonged to 19 species. Miage Glacier hosted a richer and more diverse nematode fauna than the Belvedere. The dominant genus was Plectus Bastian, 1865, a common genus in habitats at high latitude and altitude. Analysis of the feeding type of nematodes highlighted that bacterivores were dominant on Miage Glacier, while bacterivores and herbivores were more widespread on Belvedere Glacier. Predator nematodes were absent. Analysis of the food-web structure indicated that nematode assemblages on both glaciers were typical of environments with depleted food availability, probably resulting from instability of the glacier surface and the short exposure of sediments, preventing the evolution of true soil and enrichment in organic matter of the debris. The scarcity of bacterial primary producers suggests that deposition of allochthonous organic matter is the principal organic carbon source in this environment.

The use of freshwater nematodes in the field of ecotoxicology and applied ecology is reviewed. After a general introduction to quality assessment of freshwater habitats, we try to elucidate the suitability of nematodes in this field of science and application. With examples of studies using nematodes as test organisms for single-species tests, as well as studies investigating nematode communities in unpolluted and polluted habitats, we highlight different fields of application and various methods for assessing the quality of ecosystems by focusing on studies performed in freshwater environments. © CAB International 2006.

The impact of the moss substratum (soil or rock) on the species composition of nematode assemblages was investigated. Samples of different species of moss were collected at several stations in Italy. Nematode density was very variable between samples and substrata, but nematode assemblages were very similar in trophic group structure and diversity. Predator dominance and the high percentage of Dorylaimida indicate the good quality of the investigated stations. Species richness and biomass were higher in mosses growing on soil where large nematodes such as Aporcelaimellus obtusicaudatus were abundant. No clear substratum-dependent species pattern was found: only Tripylella intermedia appears to be exclusive for mosses growing on rocks. Prionchulus muscorum and Plectus acuminatus were the commonest species and occurred in almost all samples. By comparing our moss communities with those of other European communities reported in the literature, we detected significant differences between continental and Mediterranean communities. © Koninklijke Brill NV, 2006.

The Taro and Ticino rivers were sampled (maximum 15 cm depth) for nematodes during I year at three sites for each river and some ecological parameters were measured. The yearly mean abundance of nematodes in the river Taro was 23 individuals/ 10 cm 2 and in the river Ticino 79 individuals/10 cm(2). In the two rivers five to 15 and three to ten species, respectively, were found. The highest station (Taro 1) of the river Taro was significantly different from all the other Taro and Ticino stations both for number and species composition: bacterial feeders were the dominant group in Taro I (mean Maturity Index (MI) was 2.25), whereas unicellular eukaryote feeders dominated the other Taro and Ticino sites (mean MI of 2.85). Chromadorina bioculata was the most common species in both rivers, except at Taro 1, where Eumonhystera dispar dominated. Significant correlations were found between conductivity and unicellular eukaryote feeders and bacterial feeders. For the first time the Distinctness Index Delta(+) is used for freshwater nematodes. Comparing our communities with other Italian rivers (data taken from the literature), we detected significant differences between polluted and not polluted habitats.

Soft X-ray Contact Microscopy (SXCM) of Caenorhabditis elegans nematodes with typical length similar to 800 mum and diameter similar to 30 mum has been performed using the PALS laser source of wavelength lambda = 1.314 mum and pulse duration tau ( FWHM) = 400 ps. Pulsed soft X-rays were generated using molybdenum and gold targets with laser intensities I greater than or equal to 10(14) W/cm(2). Images have been recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Cuticle features and several internal organs have been identified in the SXCM images including lateral field, cuticle annuli, pharynx, and hypodermal and neuronal cell nuclei.

We report the results of a microspectroscopy study on the Fourier transform infrared (FT-IR) absorption spectra of Caenorhabditis elegans, collected from the different parts of a single intact specimen - pharynx, intestine and tail regions. The principal absorption bands were assigned to the molecular species present in C. elegans, with an excellent reproducibility for the pharynx spectrum. These results enabled us to explore if FT-IR microspectroscopy could offer a new tool for nematode identification. As an example, the discrimination among four well characterised nematode taxa is reported. The FT-IR results completely match those obtained by Blaxter and colleagues through molecular biology [Nature 392 (1998) 71]. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

Soft X-ray Contact Microscopy (SXCM) experiments have been performed on the nematode Caenorhabditis elegans using the Prague Asterix Iodine Laser System (PALS). Pulsed X-rays were generated using gold and molybdenum targets with laser intensities 1 greater than or equal to 10(14) W/cm(2) to record the contact images of C. elegans on PMMA photoresists. Results were analyzed using an atomic force microscope operating in constant force mode. Our results show some characteristic features of the C. elegans and the suitability of the sxcm technique for the study of multi-cellular specimens.

A new species of the genus Thalassogenus Andrassy, 1973 is described and dedicated to the memory of Prof. Dr. M. Brzeski. It was extracted from Selaginella sp., La Paz Falls, Costa Rica. The main diagnostic feature is the long tail (108-178 mum, c' = 2.6-4.3); also body length tends to be greater than in the other species (2.3-3.2 mm vs 1.7-2.5). Opinions vary with regard to the systematic position of the genus; Oncholaimina (Pelagonematidae) or Mononchina. We show that it belongs to Oncholaimina, where it represents a separate family. The genus is now known from four widely spaced regions in the tropics - India, New Guinea, Samoa Islands and Central America. The presence of an ocellus suggests that species of this genus are recent immigrants of freshwater