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A Caenorhabditis elegans wild type defies the temperature-size rule owing to a single nucleotide polymorphism in tra-3.

Kammenga JE, Doroszuk A, Riksen JA, Hazendonk E, Spiridon L, Petrescu AJ, Tijsterman M, Plasterk RH, Bakker J - PLoS Genet. (2007)

Bottom Line: We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it.Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain.These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands. Jan.Kammenga@wur.nl

ABSTRACT
Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature-size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature-size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 x CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

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Effect of Temperature and TG on Body Size in C. elegansWe measured body size in the mutants tra-3(e1107) (size of pseudomales is comparable to normal males but smaller than hermaphrodites) exposed to temperature and TG (including DMSO control). Also shown are the body sizes of the suppressed tra-3 mutant tra-3(e1107)sup-24(st354)IV, and tra-3(e2333) exposed to temperature, and wild-type N2 (+/+) exposed to TG and DMSO control. * = significant at 0.01 < p < 0.05 and *** = significant at p < 0.001. Bars are standard deviation. +/+:F(1,28) = 5.25, CB:F(1,47) = 0.67, tra-3(e1107):F(1,38) = 1.43, tra-3(e1107) 24 °C DMSO versus TG:F(1,14) = 1.77, tra-3(e1107)sup-24(st354) F(1,22) = 14.44, tra-3(e2333):F(1,27) = 1.52, and +/+ 24 °C DMSO versus TG:F(1,8) = 6.65.
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pgen-0030034-g004: Effect of Temperature and TG on Body Size in C. elegansWe measured body size in the mutants tra-3(e1107) (size of pseudomales is comparable to normal males but smaller than hermaphrodites) exposed to temperature and TG (including DMSO control). Also shown are the body sizes of the suppressed tra-3 mutant tra-3(e1107)sup-24(st354)IV, and tra-3(e2333) exposed to temperature, and wild-type N2 (+/+) exposed to TG and DMSO control. * = significant at 0.01 < p < 0.05 and *** = significant at p < 0.001. Bars are standard deviation. +/+:F(1,28) = 5.25, CB:F(1,47) = 0.67, tra-3(e1107):F(1,38) = 1.43, tra-3(e1107) 24 °C DMSO versus TG:F(1,14) = 1.77, tra-3(e1107)sup-24(st354) F(1,22) = 14.44, tra-3(e2333):F(1,27) = 1.52, and +/+ 24 °C DMSO versus TG:F(1,8) = 6.65.

Mentions: To investigate the hypothesis that tra-3 controlled the TRB, we first sequenced this region in CB. One SNP was found within the coding region where phenylanaline-96 in N2 was mutated into leucine-96 in CB. To see whether other tra-3 mutants displayed the same phenotype as observed in CB, we selected two homozygous artificial allelic mutants in an N2 background, tra-3(e1107) carrying a nonsense mutation [34] and tra-3(e2333). We also sequenced tra-3(e2333) in the ORF ± 1 kb and found a nonsense mutation at nucleotide position 1,779 (G to A) of the spliced tra-3 transcript. This resulted in a premature stop (W to stop) at position 593 of the TRA-3 protein. Both mutants were phenotyped for body size at 12 °C and 24 °C and compared to the wild-type N2. Like CB, body size was not affected by temperature in both mutants (Figure 4). The N2 phenotype was rescued by the fully suppressed mutant tra-3(e1107)sup-24(st354)IV, which promotes translational readthrough of the tra-3(e1107) mutation (Figure 4).


A Caenorhabditis elegans wild type defies the temperature-size rule owing to a single nucleotide polymorphism in tra-3.

Kammenga JE, Doroszuk A, Riksen JA, Hazendonk E, Spiridon L, Petrescu AJ, Tijsterman M, Plasterk RH, Bakker J - PLoS Genet. (2007)

Effect of Temperature and TG on Body Size in C. elegansWe measured body size in the mutants tra-3(e1107) (size of pseudomales is comparable to normal males but smaller than hermaphrodites) exposed to temperature and TG (including DMSO control). Also shown are the body sizes of the suppressed tra-3 mutant tra-3(e1107)sup-24(st354)IV, and tra-3(e2333) exposed to temperature, and wild-type N2 (+/+) exposed to TG and DMSO control. * = significant at 0.01 < p < 0.05 and *** = significant at p < 0.001. Bars are standard deviation. +/+:F(1,28) = 5.25, CB:F(1,47) = 0.67, tra-3(e1107):F(1,38) = 1.43, tra-3(e1107) 24 °C DMSO versus TG:F(1,14) = 1.77, tra-3(e1107)sup-24(st354) F(1,22) = 14.44, tra-3(e2333):F(1,27) = 1.52, and +/+ 24 °C DMSO versus TG:F(1,8) = 6.65.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1808073&req=5

pgen-0030034-g004: Effect of Temperature and TG on Body Size in C. elegansWe measured body size in the mutants tra-3(e1107) (size of pseudomales is comparable to normal males but smaller than hermaphrodites) exposed to temperature and TG (including DMSO control). Also shown are the body sizes of the suppressed tra-3 mutant tra-3(e1107)sup-24(st354)IV, and tra-3(e2333) exposed to temperature, and wild-type N2 (+/+) exposed to TG and DMSO control. * = significant at 0.01 < p < 0.05 and *** = significant at p < 0.001. Bars are standard deviation. +/+:F(1,28) = 5.25, CB:F(1,47) = 0.67, tra-3(e1107):F(1,38) = 1.43, tra-3(e1107) 24 °C DMSO versus TG:F(1,14) = 1.77, tra-3(e1107)sup-24(st354) F(1,22) = 14.44, tra-3(e2333):F(1,27) = 1.52, and +/+ 24 °C DMSO versus TG:F(1,8) = 6.65.
Mentions: To investigate the hypothesis that tra-3 controlled the TRB, we first sequenced this region in CB. One SNP was found within the coding region where phenylanaline-96 in N2 was mutated into leucine-96 in CB. To see whether other tra-3 mutants displayed the same phenotype as observed in CB, we selected two homozygous artificial allelic mutants in an N2 background, tra-3(e1107) carrying a nonsense mutation [34] and tra-3(e2333). We also sequenced tra-3(e2333) in the ORF ± 1 kb and found a nonsense mutation at nucleotide position 1,779 (G to A) of the spliced tra-3 transcript. This resulted in a premature stop (W to stop) at position 593 of the TRA-3 protein. Both mutants were phenotyped for body size at 12 °C and 24 °C and compared to the wild-type N2. Like CB, body size was not affected by temperature in both mutants (Figure 4). The N2 phenotype was rescued by the fully suppressed mutant tra-3(e1107)sup-24(st354)IV, which promotes translational readthrough of the tra-3(e1107) mutation (Figure 4).

Bottom Line: We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it.Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain.These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands. Jan.Kammenga@wur.nl

ABSTRACT
Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature-size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature-size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 x CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

Show MeSH
Related in: MedlinePlus