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Glanville fritillary larvae from three larval families (full-sib) exposed to alternative temperature treatments during final instar stage.

ABSTRACT: We combined heritability analysis of larval development rate with a global expression analysis of this phenotype to investigate genotype by environment interactions across three ecologically relevant temperatures in the Glanville fritillary butterfly (Melitaea cinxia). We focused upon the development of final instar caterpillars which is greatly affected by temperature, and during this stage the caterpillars build up most of the resources for adult life. Second generation, lab reared larvae, initially collected from the Åland metapopulation, were reared in standard lab condition until 6th larval instar. At the beginning of the final (7th) instar stage the larvae were separated into of three temperature conditions: Cold treatment (temperature profile: 8°C 18:00-9:59, 14°C 10:00-11:59, 20°C 12:00-15:59 and 14°C 16:00-17:59) Standard treatment (temperature profile: 15°C 17:00-6:59, 18°C 7:00-8:59, 22°C 9:00-10:59 and 26°C 11:00-16:59) Hot treatment (temperature profile: 8°C 20:00-7:59, 15°C 8:00-9:59, 35°C 10:00-17:59 and 15°C 18:00-19:59) The temperature profiles mimic the diurnal thermal variation of the natural habitat (Åland islands) of samples. Cold treatment mimics a cool and cloudy summer, Standard represents an average temperature profile in the Åland islands and Hot treatment mimics an exceptionally hot and sunny summer, with cold night-time temperatures. The experiment contained several larval families (full-sib) of which three were selected for gene expression analysis. Samples were snap-frozen in liquid nitrogen during mid-development (after 6, 5 and 4 days, for Cold, Standard and Hot respectively). Additional larvae from the same treatments were assayed for survival and growth. Gene expression was analyzed using a mixed model approach to identify genes with potential heritable expression variation (variation among families), genes with plastic expression responses (treatment induced changes) and genes with treatment dependent expression that varies among families (family by treatment interactions).

ORGANISM(S): Melitaea cinxia

PROVIDER: GSE32203 | GEO | 2014/01/01

SECONDARY ACCESSION(S): PRJNA147371

REPOSITORIES: GEO

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Project description:We combined heritability analysis of larval development rate with a global expression analysis of this phenotype to investigate genotype by environment interactions across three ecologically relevant temperatures in the Glanville fritillary butterfly (Melitaea cinxia). We focused upon the development of final instar caterpillars which is greatly affected by temperature, and during this stage the caterpillars build up most of the resources for adult life. Second generation, lab reared larvae, initially collected from the M-CM-^Eland metapopulation, were reared in standard lab condition until 6th larval instar. At the beginning of the final (7th) instar stage the larvae were separated into of three temperature conditions: Cold treatment (temperature profile: 8M-BM-0C 18:00-9:59, 14M-BM-0C 10:00-11:59, 20M-BM-0C 12:00-15:59 and 14M-BM-0C 16:00-17:59) Standard treatment (temperature profile: 15M-BM-0C 17:00-6:59, 18M-BM-0C 7:00-8:59, 22M-BM-0C 9:00-10:59 and 26M-BM-0C 11:00-16:59) Hot treatment (temperature profile: 8M-BM-0C 20:00-7:59, 15M-BM-0C 8:00-9:59, 35M-BM-0C 10:00-17:59 and 15M-BM-0C 18:00-19:59) The temperature profiles mimic the diurnal thermal variation of the natural habitat (M-CM-^Eland islands) of samples. Cold treatment mimics a cool and cloudy summer, Standard represents an average temperature profile in the M-CM-^Eland islands and Hot treatment mimics an exceptionally hot and sunny summer, with cold night-time temperatures. The experiment contained several larval families (full-sib) of which three were selected for gene expression analysis. Samples were snap-frozen in liquid nitrogen during mid-development (after 6, 5 and 4 days, for Cold, Standard and Hot respectively). Additional larvae from the same treatments were assayed for survival and growth. Gene expression was analyzed using a mixed model approach to identify genes with potential heritable expression variation (variation among families), genes with plastic expression responses (treatment induced changes) and genes with treatment dependent expression that varies among families (family by treatment interactions). Full-sib larvae from three families (N170, N74 and O171) were exposed to three temperature treatments (Cold, Standard and Hot) during final (7th) instar stage. A total of 35 samples were used to analyze family, treatment and family by treatment interactions in gene expression, using a mixed model approach. This included 3 biological replicates in Cold and Hot treatments from each family and 5-6 biological replicates in Standard (5 in O171) per family. Techinal replicates from each family and additional techical replicates in family O171 (including dye swap replicates) were used to assess robustness of the findings.

Project description:Purpose: We aimed at i) obtaining insight into how a thermophile organism reacts to cold stress, and ii) evaluating the impact of HGT candidates on the acclimation process to temperature decrease. Methods: The experimental design followed a temperature shift timeline: after two weeks of cultivation at 42°C, constant illumination (90 μE) and constant shaking (160 rpm) in photoautotrophic conditions the first sampling took place (Hot_T48_1) and the cultures of G.sulphuraria were swiftly moved to 28°C ( = cold temperature). "Cold" samples were taken after 3h (Cold_T3_2), 12h (Cold_T12_3) and 48h (Cold_T48_4). After cold treatment at 28°C for 48 hours, the G. sulphuraria was then switched to 46°C for 48 hours (="Hot"). Again, samples were taken after 3h (Hot_T3_5), 12h (Hot_T12_6) and 48h (Hot_T48_7). Altogether, a 48h temperature timeshift at 28°C and successive recovery at 46°C were targeted for sampling. Results: Galdieria sulphuraria is a unicellular red alga that lives in hot, acidic, toxic metal-rich, volcanic environments, where few other organisms survive. Its genome harbours up to 5% of genes most likely acquired through horizontal gene transfer. These genes probably contributed to G. sulphuraria’s adaptation to its extreme habitats, resulting in today’s polyextremophilic traits. Here, we applied RNA-sequencing to obtain insights into the acclimation of a thermophilic organism towards temperatures below its growth optimum and to study how horizontally acquired genes contribute to cold acclimation. A decrease in growth temperature from 42 °C/46 °C to 28 °C resulted in an upregulation of ribosome biosynthesis, while excreted proteins, probably components of the cell wall, were downregulated. Photosynthesis was suppressed at cold temperatures, and transcript abundances indicated that C-metabolism switched from gluconeogenesis to glycogen degradation. Folate cycle and S-adenosylmethionine cycle (one-carbon metabolism) were transcriptionally upregulated, probably to drive the biosynthesis of betaine. All these cold-induced changes in gene expression were reversible upon temperature increase. Numerous genes acquired by horizontal gene transfer displayed pronounced temperature-dependent expression changes, corroborating the view that these genes contributed to adaptive evolution in G. sulphuraria.

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Glanville fritillary larvae from three larval families (full-sib) exposed to alternative temperature treatments during final instar stage.

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