China
Africa
Explore chapters and articles related to this topic
*
Published in Michael Hehenberger, Zhi Xia, Huanming Yang, Our Animal Connection, 2020
Michael Hehenberger, Zhi Xia, Huanming Yang
The nematode is easy to culture and can be grown on agar medium and fed on E. coli. It can be stored in low temperature liquid nitrogen for several years. Adult nematodes are about 1.5 mm long and hermaphroditic. The adult organism is composed of a well-defined number of (959) somatic cells. Each cell has a clear morphological, developmental, and genetic background. The growth cycle is short, and the fertilized embryo can hatch into a free-living larva within 12 hours. The larva can mature in 40 hours. Adults can produce hundreds of offspring in about 4 days. Mutants were easily obtained in various ways, and the phenotypic characteristics were obvious. The genomic study of nematodes began in 1990, and genome sequencing and analysis were completed in 1998 and published on December 24 of that year. The C. elegans genome is about 100 Mb in size and consists of 6 chromosomes with about 20,000 coding genes. 60% of the genes are highly homologous to other eukaryotes.
Soil: Fauna
Published in Yeqiao Wang, Landscape and Land Capacity, 2020
Soil fauna are responsive to changes in their environment. This responsiveness, which occurs in part because the soil is their habitat, makes soil fauna useful indicator organisms of disturbance, recovery, and soil quality.[42] Nematodes, for example, have been used as indicators of ecosystem recovery and function, maturity, and the soil food web.[43,44] Earthworms are utilized as indicators of pollution, including heavy metals. However, their diversity in niche separation may make it difficult to interpret responses. Currently, we remain limited not only by scale of resolution in sampling and identification, but by what we do not know about the biology and ecology of unidentified and even identified organisms. Barbercheck et al.[26] suggested separating Collembola by habitat type for effectiveness of using Collembola as indicators. However, relying on one indicator or group of indicators to describe effects of disturbance among ecosystems is not advised.[19,26]
*
Published in Michael Hehenberger, Zhi Xia, Our Animal Connection, 2019
The nematode is easy to culture and can be grown on agar medium and fed on E. coli. It can be stored in low temperature liquid nitrogen for several years. Adult nematodes are about 1.5 mm long and hermaphroditic. The adult organism is composed of a well-defined number of (959) somatic cells. Each cell has a clear morphological, developmental, and genetic background. The growth cycle is short, and the fertilized embryo can hatch into a free-living larva within 12 hours. The larva can mature in 40 hours. Adults can produce hundreds of offspring in about 4 days. Mutants were easily obtained in various ways, and the phenotypic characteristics were obvious. The genomic study of nematodes began in 1990, and genome sequencing and analysis were completed in 1998 and published on December 24 of that year. The C. elegans genome is about 100 Mb in size and consists of 6 chromosomes with about 20,000 coding genes. 60% of the genes are highly homologous to other eukaryotes.
Impacts of metallic nanoparticles and transformed products on soil health
Published in Critical Reviews in Environmental Science and Technology, 2021
Wenjie Sun, Fugen Dou, Cong Li, Xingmao Ma, Lena Q. Ma
Besides microbes, nematodes and earthworms also play an important role in maintaining soil health. While plant parasitic nematodes have received tremendous attention due to their potential harmful effects on agriculture, most of nematodes in soil are free-living and beneficial to soil health. Some nematodes are bacteria and fungi feeders, so their population affects the microbial community in soil. Studies on the impacts of MNPs on nematodes are relatively scarce, with most focusing on the most known nematode species: C. elegans (Starnes et al., 2019). For example, Starnes et al. (2019) investigated the toxicity of ZnONPs and their transformed products on C. elegans and found that both sulfidized and phosphatized ZnONPs displayed lower toxicity to nematode than pristine ZnONPs, which showed similar toxicity as Zn ions. The authors contributed the higher toxicity of ZnONPs than their transformed products to the higher dissolution rate of ZnONPs. However, different forms of Zn resulted in different gene expressions at the transcriptomic level, suggesting that the toxicity of ZnONPs cannot be fully explained by the dissolved Zn ions alone.
Xenobiotic metabolism and transport in Caenorhabditis elegans
Published in Journal of Toxicology and Environmental Health, Part B, 2021
Jessica H. Hartman, Samuel J. Widmayer, Christina M. Bergemann, Dillon E. King, Katherine S. Morton, Riccardo F. Romersi, Laura E. Jameson, Maxwell C. K. Leung, Erik C. Andersen, Stefan Taubert, Joel N. Meyer
Finally, although this review focuses on C. elegans as a toxicology model for human health, C. elegans and other nematodes may also serve broader ecological health goals. Nematodes, or communities of nematode species, may serve as useful bioindicator species in ecotoxicology. The species diversity of nematode communities is one measure of ecological integrity, and is sensitive to environmental changes (Franco et al. 2019). Morphological identification of nematode species may be time-consuming and requires expertise. However, recent studies demonstrated that metabarcoding samples of nematode communities is similarly efficient to morphological species identification, and may be implemented rapidly (De Ley et al. 2005; Schenk et al. 2020). Further, given relevance for both human health and ecotoxicology, and the ability to be studied both in the field and in the lab, experiments with C. elegans has strong potential to help bridge ecotoxicological and human health research. Research with nematodes might be used in frameworks that were developed for integrating data from different species from molecular (Mattingly et al. 2006), biochemical (Harborne 1988), and pathological (Snyder et al. 2010) to ecological (Monosson 2012) levels, approaches that more recently were incorporated into the EcoHealth and OneHealth concepts (Brooks et al. 2020; Haschek et al. 2019; Perez and Pierce WiseSr. 2018).
The Mortality of Nematodes in Drinking Water in the Presence of Ozone, Chlorine Dioxide, and Chlorine
Published in Ozone: Science & Engineering, 2020
Jasna Kos, Mirjana Brmež, Marinko Markić, Laszlo Sipos
Nematodes can be a threat to human health because they can ingest and protect pathogenic bacteria (Caldwell et al. 2003; Kenney et al. 2004) from inactivation by chlorine and monochloramines, even when 90% of the nematodes have been immobilized by treatment with 95 mg/L chlorine (Chang, Woodward, and Kabler 1960). Free-living nematodes Pristionchus lheritieri with swallowed Salmonella typhi and Salmonella wichita bacteria survived the free chlorine exposure at 10 mg/L for 15 min, and bacteria were released by excretion (Smerda, Jensen, and Anderson 1971). Moreover, nematodes may tolerate chlorination processes with 10 mg/L free chlorine for up to 65 min or with 100 mg/L free chlorine for up to 5 min at 21°C (Chantanao and Jensen 1969a). However, Chang and Berg (Chang, Woodward, and Kabler 1960) found that concentrations of 2.5 to 3.0 mg/L of free chlorine for 120 min and 15 to 45 mg/L of free chlorine for 1 min were not deadly to free-living nematodes. Free chlorine residuals as high as 95 to 100 mg/liter for 5 min killed only 40%-50% of the nematodes. Additionally, residual free chlorine at concentrations of 95 to 100 mg/L inactivates only 40% to 50% of some species of nematodes in 5 min (Rhabditis, Cheilohus, Diplogaster, Apheluncus, Cephalopus, Dorylaimus, Tubatrix), while 10 to 20% are still active after 10 minutes.