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Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La
BACKGROUND: Principal malaria vectors in Africa, An. gambiae and An. coluzzii, share an inversion polymorphism on the left arm of chromosome 2 (2La/2L+(a)) that is distributed non-randomly in the environment. Genomic sequencing studies support the role of strong natural selection in maintaining stee...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991895/ https://www.ncbi.nlm.nih.gov/pubmed/24721548 http://dx.doi.org/10.1186/1756-3305-7-176 |
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author | Reidenbach, Kyanne R Cheng, Changde Liu, Fang Liu, Cheng Besansky, Nora J Syed, Zainulabeuddin |
author_facet | Reidenbach, Kyanne R Cheng, Changde Liu, Fang Liu, Cheng Besansky, Nora J Syed, Zainulabeuddin |
author_sort | Reidenbach, Kyanne R |
collection | PubMed |
description | BACKGROUND: Principal malaria vectors in Africa, An. gambiae and An. coluzzii, share an inversion polymorphism on the left arm of chromosome 2 (2La/2L+(a)) that is distributed non-randomly in the environment. Genomic sequencing studies support the role of strong natural selection in maintaining steep clines in 2La inversion frequency along environmental gradients of aridity, and physiological studies have directly implicated 2La in heat and desiccation tolerance, but the precise genetic basis and the underlying behavioral and physiological mechanisms remain unknown. As the insect cuticle is the primary barrier to water loss, differences in cuticle thickness and/or epicuticular waterproofing associated with alternative 2La arrangements might help explain differences in desiccation resistance. METHODS: To test that hypothesis, two subcolonies of both An. gambiae and An. coluzzii were established that were fixed for alternative 2La arrangements (2La or 2L+(a)) on an otherwise homosequential and shared genetic background. Adult mosquitoes reared under controlled environmental conditions (benign or arid) for eight days post-eclosion were collected and analyzed. Measurements of cuticle thickness were made based on scanning electron microscopy, and cuticular hydrocarbon (CHC) composition was evaluated by gas chromatography–mass spectrometry. RESULTS: After removing the allometric effects of body weight, differences in mean cuticle thickness were found between alternative 2La karyotypes, but not between alternative environments. Moreover, the thicker cuticle of the An. coluzzii 2La karyotype was contrary to the known higher rate of water loss of this karyotype relative to 2L+(a). On the other hand, quantitative differences in individual CHCs and overall CHC profiles between alternative karyotypes and environmental conditions were consistent with expectation based on previous physiological studies. CONCLUSIONS: Our results suggest that alternative arrangements of the 2La inversion are associated with differences in cuticle thickness and CHC composition, but that only CHC composition appears to be relevant for desiccation resistance. Differences in the CHC composition were consistent with previous findings of a lower rate of water loss for the 2L+(a) karyotype at eight days post-eclosion, suggesting that CHC composition is an important strategy for maintaining water balance in this genetic background, but not for 2La. Despite a higher rate of water loss at eight days, higher body water content of the 2La karyotype confers a level of desiccation resistance equivalent to that of the 2L+(a) karyotype. |
format | Online Article Text |
id | pubmed-3991895 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-39918952014-04-20 Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La Reidenbach, Kyanne R Cheng, Changde Liu, Fang Liu, Cheng Besansky, Nora J Syed, Zainulabeuddin Parasit Vectors Research BACKGROUND: Principal malaria vectors in Africa, An. gambiae and An. coluzzii, share an inversion polymorphism on the left arm of chromosome 2 (2La/2L+(a)) that is distributed non-randomly in the environment. Genomic sequencing studies support the role of strong natural selection in maintaining steep clines in 2La inversion frequency along environmental gradients of aridity, and physiological studies have directly implicated 2La in heat and desiccation tolerance, but the precise genetic basis and the underlying behavioral and physiological mechanisms remain unknown. As the insect cuticle is the primary barrier to water loss, differences in cuticle thickness and/or epicuticular waterproofing associated with alternative 2La arrangements might help explain differences in desiccation resistance. METHODS: To test that hypothesis, two subcolonies of both An. gambiae and An. coluzzii were established that were fixed for alternative 2La arrangements (2La or 2L+(a)) on an otherwise homosequential and shared genetic background. Adult mosquitoes reared under controlled environmental conditions (benign or arid) for eight days post-eclosion were collected and analyzed. Measurements of cuticle thickness were made based on scanning electron microscopy, and cuticular hydrocarbon (CHC) composition was evaluated by gas chromatography–mass spectrometry. RESULTS: After removing the allometric effects of body weight, differences in mean cuticle thickness were found between alternative 2La karyotypes, but not between alternative environments. Moreover, the thicker cuticle of the An. coluzzii 2La karyotype was contrary to the known higher rate of water loss of this karyotype relative to 2L+(a). On the other hand, quantitative differences in individual CHCs and overall CHC profiles between alternative karyotypes and environmental conditions were consistent with expectation based on previous physiological studies. CONCLUSIONS: Our results suggest that alternative arrangements of the 2La inversion are associated with differences in cuticle thickness and CHC composition, but that only CHC composition appears to be relevant for desiccation resistance. Differences in the CHC composition were consistent with previous findings of a lower rate of water loss for the 2L+(a) karyotype at eight days post-eclosion, suggesting that CHC composition is an important strategy for maintaining water balance in this genetic background, but not for 2La. Despite a higher rate of water loss at eight days, higher body water content of the 2La karyotype confers a level of desiccation resistance equivalent to that of the 2L+(a) karyotype. BioMed Central 2014-04-10 /pmc/articles/PMC3991895/ /pubmed/24721548 http://dx.doi.org/10.1186/1756-3305-7-176 Text en Copyright © 2014 Reidenbach et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/4.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
spellingShingle | Research Reidenbach, Kyanne R Cheng, Changde Liu, Fang Liu, Cheng Besansky, Nora J Syed, Zainulabeuddin Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title | Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title_full | Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title_fullStr | Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title_full_unstemmed | Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title_short | Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La |
title_sort | cuticular differences associated with aridity acclimation in african malaria vectors carrying alternative arrangements of inversion 2la |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991895/ https://www.ncbi.nlm.nih.gov/pubmed/24721548 http://dx.doi.org/10.1186/1756-3305-7-176 |
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