Teratogenic and Genotoxic Responses of Larval Chironomus Salinarius Group (Diptera: Chironomidae) to Contaminated Sediment

Abstract

Abstract-Chironomids are important indicators of the effects of sediment-bound contaminants. However, cause-effect relationships between contaminant exposure and stress-related indicators other than growth and survival have not been demonstrated. In the laboratory, we conducted 10-d exposures of Chironomus salinarius group Kieffer larvae to mixtures of contaminated (Trenton Channel, Detroit River, MI) sediment diluted with uncontaminated, formulated sediment (sand, sculptor's clay, and potting soil) in ratios of 1:0, 1:1, 1:3, 1:7, 1:15, and 0:1. Larvae were inoculated into either recently mixed sediments or those allowed to age for 7 d. Surviving larvae were examined for mouthpart (mentum) deformities. Giant chromosomes of the salivary glands were examined for reduction in relative nucleolus diameter (RND). Proportions of larvae with mentum deformities and of larvae with reduced RND increased linearly with each doubling of concentration of contaminated sediment. Deformities and RND reduction in individual larvae were independent responses. Incidences of deformities at low contamination doses were much greater for recently mixed sediments than for more aged sediments. Sediment age did not affect incidence of reduced RND except in the most contaminated treatment. Mentum deformities and reduced RND are quantifiable sublethal attributes reflecting stress responses to sediment contamination that can complement more traditional measures (survival and growth) in chironomid sediment bioassays.

Chironomids (Diptera) and their salivary gland chromosomes as indicators of trace-metal genotoxicity

“…Essential for cellular maintenance, NORs are sites for high transcription (Hudson & Ciborowski 1996). The level of transcription is related to variations in the protein requirements of the cells.…”

“…In the majority of cells of a salivary gland, the NOR occurs at the highest activity during the 6-7 th phase of the IV larval stage (Kiknadze 1976(Kiknadze , 1978. Variations of the diameter of the NOR were measured by Hudson and Ciborowski (1996), who found that the diameters in larvae living in a heavily polluted sediment (from Trenton Channel, Detroit), were shorter than the diameters in control larvae. After acute 10 mM Cd treatment, a decrease in the activity of NOR was observed by Planello et al (2007), who used rDNA immunofluorescent probes and Northern blot analysis on total RNA.…”

“…Fax: +359 2 988 28 97. Email: michailova@zoology.bas.bg contaminants are genotoxic, even at very low concentrations (Michailova & Belcheva 1990;Aziz et al 1991;Bentivegna & Cooper 1993;Baršiene 1994;Hudson & Ciborowski 1996;Baršiene & Bucinskiene 2001;Planello et al 2007). A realistic assessment of the long-term impact of pollutants can therefore be made by including an evaluation of their mutagenic effects on the organisms inhabiting aquatic biotopes.…”

Cytotaxonomical variability of Chironomus plutnosus L. and C. anthracinus Zett. (Diptera, Chironomidae) from industrial and municipal polluted areas of Finland

“…They ap pear to be good indicators of sediment quality (HUDSON and CIBOROWSKI 1996). Even more, a correlation between several larval morphological deformities and long term chronic toxicity has been observed (WARWICK 1990) and they were proposed as a suitable indicator of pollution.…”

Invertebrates in Testing of Environmental Chemicals: Are They Alternatives?

“…(68). The polytene chromosomes of some insect species (chironomids, Drosophila) appear to be promising tools to assess the genotoxic effects of environmental contaminants (79)(80)(81)(82).…”