Project description:Whole-transcriptome gene-expression analyses are commonly performed in species that have a sequenced genome and for which microarrays are commercially available. To do such analyses in species with no or limited genome data, i.e. non-model organisms, necessary transcriptomics resources, i.e. an annotated transcriptome and a validated gene-expression microarray, must first be developed. The aim of the present study was to establish an advanced approach for developing transcriptomics resources for non-model organisms by combining next-generation sequencing (NGS) and microarray technology. We applied our approach to the non-biting midge Chironomus riparius, an ecologically relevant species that is widely used in sediment ecotoxicity testing. We sampled extensively covering all C. riparius developmental stages as well as toxicant exposed larvae and obtained from a normalized cDNA library 1.5 M NGS reads totalling 501 Mbp. Using the NGS data we developed transcriptomics resources in several steps. First, we designed 844 k probes directly on the NGS reads, as well as 76 k probes targeting expressed sequence tags of related species. These probes were tested for their affinity to C. riparius DNA and mRNA, by performing two biological experiments with a 1 M probe-selection microarray that contained the entire probe-library. Subsequently, the 1.5 M NGS reads were assembled into 23,709 isotigs and 135,082 singletons, which were associated to ~55 k, respectively, ~61 k gene ontology terms and which corresponded together to 22,593 unique protein accessions. An algorithm was developed that took the assembly and the probe affinities to DNA and mRNA into account, what resulted in 59 k highly-reliable probes that targeted uniquely 95% of the isotigs and 18% of the singletons. Concluding, our approach allowed the development of high-quality transcriptomics resources for C. riparius, and is applicable to any non-model organism. It is expected, that these resources will advance ecotoxicity testing with C. riparius as whole-transcriptome gene-expression analysis are now possible with this species. 1x 1M CGH array with Cy3 labeled C. riparius gDNA and Cy5 labeled A. gambiae gDNA. The microarray was designed against C. riparius mRNA sequencing reads, and has been used to identify trustworthy sequencing reads to design an expression array. This 1M array is therefore not functionally annotated.

Project description:Whole-transcriptome gene-expression analyses are commonly performed in species that have a sequenced genome and for which microarrays are commercially available. To do such analyses in species with no or limited genome data, i.e. non-model organisms, necessary transcriptomics resources, i.e. an annotated transcriptome and a validated gene-expression microarray, must first be developed. The aim of the present study was to establish an advanced approach for developing transcriptomics resources for non-model organisms by combining next-generation sequencing (NGS) and microarray technology. We applied our approach to the non-biting midge Chironomus riparius, an ecologically relevant species that is widely used in sediment ecotoxicity testing. We sampled extensively covering all C. riparius developmental stages as well as toxicant exposed larvae and obtained from a normalized cDNA library 1.5 M NGS reads totalling 501 Mbp. Using the NGS data we developed transcriptomics resources in several steps. First, we designed 844 k probes directly on the NGS reads, as well as 76 k probes targeting expressed sequence tags of related species. These probes were tested for their affinity to C. riparius DNA and mRNA, by performing two biological experiments with a 1 M probe-selection microarray that contained the entire probe-library. Subsequently, the 1.5 M NGS reads were assembled into 23,709 isotigs and 135,082 singletons, which were associated to ~55 k, respectively, ~61 k gene ontology terms and which corresponded together to 22,593 unique protein accessions. An algorithm was developed that took the assembly and the probe affinities to DNA and mRNA into account, what resulted in 59 k highly-reliable probes that targeted uniquely 95% of the isotigs and 18% of the singletons. Concluding, our approach allowed the development of high-quality transcriptomics resources for C. riparius, and is applicable to any non-model organism. It is expected, that these resources will advance ecotoxicity testing with C. riparius as whole-transcriptome gene-expression analysis are now possible with this species.

Project description:This study focuses on interactions between nanoparticles and a pesticide. The aim was to investigate how nano-sized aluminum oxide (410 nm) can alter the toxic effects of thiacloprid, even if no sorption between particles and the insecticide takes place. Thus, our study investigated a rather unexplored interaction. We conducted our research with larvae of Chironomus riparius and used thiacloprid as test substance as its toxicity to C. riparius is well described. The used nano-Al2O3 particles where chosen due to their suitable properties. For testing the acute effects of the interaction, we exposed larvae to thiacloprid (0.5, 1.0, 2.0, and 5.0 μg/L) and nano-Al2O3 (300 and 1000 mg/L), either solely or in binary mixtures. While thiacloprid resulted in elevated mortality, nano-Al2O3 solely did not exert any effects. Moreover, we observed an aggregation of nano-Al2O3 within the lumen of the intestinal tract of the larvae. Further results showed a significantly reduced mortality of fourth instar larvae when they were exposed to mixtures of nanoparticles and the pesticide, compared to thiacloprid alone. With increasing nano-Al2O3 concentration, this effect became gradually stronger. Additionally, chemical analyses of internal thiacloprid concentrations implicate reduced uptake of thiacloprid in animals exposed to mixtures. However, as larvae exposed to thiacloprid concentrations > 0.5 μg/L showed severe convulsions, independent of the presence or concentration of nano-Al2O3, we assume that nano-Al2O3 leads to a delay of mortality and does not entirely prevent it. As sorption measurements on pristine or defecated nano-Al2O3 did not reveal any sorptive interaction with thiacloprid, we can exclude sorption-based reduction of thiacloprid bioavailability as a mechanism behind our results. Even though we used test substances which might not co-occur in the environment in the tested concentrations, our study gives evidence for an interaction besides adsorption, which is important to generally understand how nanoparticles might affect biota.

Project description:Cellular stress responses are frequently presumed to be more sensitive than traditional ecotoxicological life cycle endpoints such as survival and growth. Yet, the focus to reduce test duration and to generate more sensitive endpoints has caused transcriptomics studies to be performed at low doses during short exposures, separately and independently from traditional ecotoxicity tests, making comparisons with life cycle endpoints indirect. Therefore we aimed to directly compare the effects on growth, survival and gene expression of the non-biting midge Chironomus riparius. To this purpose, we analyzed simultaneously life cycle and transcriptomics responses of chironomid larvae exposed to four model toxicants. We observed that already at the lowest test concentrations many transcripts were significantly differentially expressed, while the life cycle endpoints of C. riparius were hardly affected. Analysis of the differentially expressed transcripts showed that at the lowest test concentrations substantial and biologically relevant cellular stress was induced and that many transcripts responded already maximally at these lowest test concentrations. The direct comparison between molecular en life cycle responses after fourteen days of exposure revealed that gene expression is more sensitive to toxicant exposure than life cycle endpoints, underlining the potential of transcriptomics for ecotoxicity testing and environmental risk assessment. Cellular stress responses are frequently presumed to be more sensitive than traditional ecotoxicological life cycle endpoints such as survival and growth. Yet, the focus to reduce test duration and to generate more sensitive endpoints has caused transcriptomics studies to be performed at low doses during short exposures, separately and independently from traditional ecotoxicity tests, making comparisons with life cycle endpoints indirect. Therefore we aimed to directly compare the effects on growth, survival and gene expression of the non-biting midge Chironomus riparius. To this purpose, we analyzed simultaneously life cycle and transcriptomics responses of chironomid larvae exposed to four model toxicants. We observed that already at the lowest test concentrations many transcripts were significantly differentially expressed, while the life cycle endpoints of C. riparius were hardly affected. Analysis of the differentially expressed transcripts showed that at the lowest test concentrations substantial and biologically relevant cellular stress was induced and that many transcripts responded already maximally at these lowest test concentrations. The direct comparison between molecular en life cycle responses after fourteen days of exposure revealed that gene expression is more sensitive to toxicant exposure than life cycle endpoints, underlining the potential of transcriptomics for ecotoxicity testing and environmental risk assessment. Four 14-day Chironomus riparius sediment toxicity tests were conducted, one with each toxicant. The surviving larvae were individually flash frozen in liquid nitrogen. For each toxicant we analyzed the gene expression of larvae exposed to low, intermediate and high concentrations. We also included a control and a solvent control. For each treatment we analyzed 10 replicates (individual larvae).

Project description:This study measured the differential expression of genes from two populations of Wyeomyia smithii in the USA that differ in their propensity to bite over a geographic gradient. Population KC is a northern non-biting population from Maine; population WI is a southern low-frequency biting population from Florida. The mosquitoes were maintained at the University of Oregon under standard rearing conditions and run through two generations to minimize maternal and field effects. Selection for biting was conducted using ~14,000 individuals from the WI population. The environment and protocols used for selection were the same as for KC except biters were removed from their cage and placed into a separate “biting” cage with supplemental males from the same generation of the selected line. All hatch from the biting cage were used to generate the subsequent generations. This protocol was followed until the selected line had undergone 5 generation of selection. Through all generations of selection, including those that were not offered a host, hatch were placed on short days (LL:D=10:14) at 21°C to synchronize each generation and to miigate inadvertant direct selection on development time, generation time, or the timing of reproductive allocation. After adults of a given generation had died, their offspring were transferred to long days and reared to adulthood, as above. During experiments, all animals were in good physical condition. Animal heads were dissected then transferred into 1.5-ml microcentrifuge tubes and shock-frozen in liquid nitrogen. Samples were short-term stored at -80°C. For all experimental conditions, four independent replicates (50 heads each) were analyzed. This GEO record is for three comparisons among the three populations: (EXP1) non-biters in the base population (WI) versus biting individuals in the WI line selected for biting (WIOB) over 5 generations of selection (WI vs WIOB); (EXP2) WIOB versus northern obligate non-biters (KC); (3) WI versus KC (n=4 per treatment group for each population).

Project description:Cellular stress responses are frequently presumed to be more sensitive than traditional ecotoxicological life cycle endpoints such as survival and growth. Yet, the focus to reduce test duration and to generate more sensitive endpoints has caused transcriptomics studies to be performed at low doses during short exposures, separately and independently from traditional ecotoxicity tests, making comparisons with life cycle endpoints indirect. Therefore we aimed to directly compare the effects on growth, survival and gene expression of the non-biting midge Chironomus riparius. To this purpose, we analyzed simultaneously life cycle and transcriptomics responses of chironomid larvae exposed to four model toxicants. We observed that already at the lowest test concentrations many transcripts were significantly differentially expressed, while the life cycle endpoints of C. riparius were hardly affected. Analysis of the differentially expressed transcripts showed that at the lowest test concentrations substantial and biologically relevant cellular stress was induced and that many transcripts responded already maximally at these lowest test concentrations. The direct comparison between molecular en life cycle responses after fourteen days of exposure revealed that gene expression is more sensitive to toxicant exposure than life cycle endpoints, underlining the potential of transcriptomics for ecotoxicity testing and environmental risk assessment. Cellular stress responses are frequently presumed to be more sensitive than traditional ecotoxicological life cycle endpoints such as survival and growth. Yet, the focus to reduce test duration and to generate more sensitive endpoints has caused transcriptomics studies to be performed at low doses during short exposures, separately and independently from traditional ecotoxicity tests, making comparisons with life cycle endpoints indirect. Therefore we aimed to directly compare the effects on growth, survival and gene expression of the non-biting midge Chironomus riparius. To this purpose, we analyzed simultaneously life cycle and transcriptomics responses of chironomid larvae exposed to four model toxicants. We observed that already at the lowest test concentrations many transcripts were significantly differentially expressed, while the life cycle endpoints of C. riparius were hardly affected. Analysis of the differentially expressed transcripts showed that at the lowest test concentrations substantial and biologically relevant cellular stress was induced and that many transcripts responded already maximally at these lowest test concentrations. The direct comparison between molecular en life cycle responses after fourteen days of exposure revealed that gene expression is more sensitive to toxicant exposure than life cycle endpoints, underlining the potential of transcriptomics for ecotoxicity testing and environmental risk assessment.

			Action	DRS
		Other
	ERR14955800_1.fastq.gz	Fastqsanger.gz
	ERR14955800_2.fastq.gz	Fastqsanger.gz
	ERR14955801_1.fastq.gz	Fastqsanger.gz
	ERR14955801_2.fastq.gz	Fastqsanger.gz

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A multigenerational study can detect the evolutionary response to BaP exposure in the non-biting freshwater midge Chironomus riparius

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