Biology subjects

Theissinger, K.

Publications and source records attributed to Theissinger, K..

3 recordsLinked to original sources

bioRxiv2021

Low Temperatures Lead to Higher Toxicity of the Fungicide Folpet to Larval Stages of Rana temporaria and Bufotes viridis

Pesticides are one of the main drivers of the worldwide amphibian decline. Their actual toxicity depends on a number of factors, like the species in focus or the developmental stage of exposed individuals. As ectothermic species, the metabolism of amphibians is influenced by ambient temperature. Therefore, temperature also affects metabolic rates and thus processes that might enhance or reduce toxic effects. Studies about the interactive effect of temperature and toxicity on amphibians are rare and deliver contrasting results. To investigate the temperature-dependent pesticide sensitivity of larvae of two European species we conducted acute toxicity tests for the viticultural fungicide Folpan(R) 500 SC with the active ingredient folpet at different temperatures (6{degrees}C, 11{degrees}C, 16{degrees}C, 21{degrees}C, 26{degrees}C). Sensitivity of Rana temporaria and Bufotes viridis was highly affected by temperature: early larvae (Gosner stage 20) were about twice more sensitive to Folpan(R) 500 SC at 6{degrees}C compared to 21{degrees}C. Next to temperature, species and developmental stage of larvae had an effect on sensitivity. The most sensitive individuals (early stages of R. temporaria at 6{degrees}C) were 14.5 times more sensitive than the least sensitive ones (early stages of B. viridis at 26{degrees}C). Our results raise concerns about typical ecotoxicological studies with amphibians that are often conducted at temperatures between 15{degrees}C and 20{degrees}C. We suggest that future test designs should be performed at temperatures that reflect the temperature range amphibians are exposed to in their natural habitats. Variations in the sensitivity due to temperature should also be considered as an uncertainty factor in upcoming environmental risk assessments for amphibians.

pharmacology and toxicology↗

bioRxiv2021

Mating Strategies Of Invasive Versus Indigenous Crayfish: Multiple Paternity As Driver For Invasion Success?

The invasive spiny-cheek crayfish (Faxonius limosus) has been able to colonize many European waterbodies since its first introduction into Europe, threatening the indigenous crayfish fauna. Faxonius limosus remarkable reproductive plasticity has been suggested as an important factor contributing to this species alarming invasiveness. This is the first study comparing the reproductive strategies of an invasive (F. limosus) and a sympatric indigenous crayfish (Pontastacus leptodactylus). We investigated if and how parthenogenesis and multiple paternity contribute to the invasion process in the River Danube. Using microsatellites, we genotyped the offspring and their mothers of 11 clutches of F. limosus and 18 clutches of P. leptodactylus. While no parthenogenesis has been found in F. limosus populations, multiple paternity has been detected for the first time in both species, with comparable incidence. The results of the study indicate that multiple paternity does not play a dominant role in F. limosus successful colonization of the Danube. However, the presented results have to be regarded as pilot study, with a limited number of samples and loci investigated. Given the relevance of mating system knowledge for management measures, future studies with larger sample number could provide precious contributions to the conservation actions.

ecology↗

bioRxiv2021

Comparative transcriptome analysis of noble crayfish and marbled crayfish immune response to Aphanomyces astaci challenges

Introduction of invasive North American crayfish species and their pathogen Aphanomyces astaci has significantly contributed to the decline of European freshwater crayfish populations. In this study, noble crayfish, a susceptible native European species, and marbled crayfish, an invasive disease-resistant species, were challenged with haplogroup A (low virulence) and haplogroup B (high virulence) strain of A. astaci. Hepatopancreatic tissue was isolated 3 and 21 days post-challenge. Our results revealed strong up-regulation in expression levels of the prophenoloxidase cascade immune-related genes in the haplogroup B challenged noble crayfish 3 days post-challenge. In the marbled crayfish, we observed an up-regulation of immune system relevant genes (DSCAM, AP, ALFs, CTLs and hemocyanin) 3 days post-challenge. This response highlights the marbled crayfish capability of building the immune tolerance. Furthermore, we successfully characterised several novel immune related gene groups in both crayfish species, contributing to our current understanding of crayfish immune related genes landscape. Graphical abstracta) Study species noble crayfish (Astacus astacus) in purple and marbled crayfish (Procambarus virginalis) in green challenged with the pathogen Aphanomyces astaci haplogroup A (Hap A) strain of low virulence and haplogroup B (Hap B) strain of high virulence. b) Sampling scheme of the infection experiment: 5 individuals were taken from the experiment three- and 21-days post-challenge. From each individual, a hepatopancreas sample was taken, followed by RNA isolation and sequencing. c) De novo transcriptome assembly and annotation were conducted for each species. d) Differential gene expression analysis revealed the distinct immune response in the noble crayfish 3 days post-challenge with the Hap B strain of A. astaci and marbled crayfish 3 days post-challenge with the Hap A strain of A. astaci. Immune related DEGs were not present in either species 21 days post-challenge with A. astaci. e) Noble crayfish challenged with the Hap B strain of A. astaci were acutely infected and ultimately moribund, while the A. astaci Hap A challenged marbled crayfish showed high resistance to the pathogen, resulting infected without any mortality. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/445163v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@d1830aorg.highwire.dtl.DTLVardef@f2196forg.highwire.dtl.DTLVardef@63c8f2org.highwire.dtl.DTLVardef@11da1b6_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗