Eads Brian D, Colbourne John K, Bohuski Elizabeth, Andrews Justen
The Center for Genomics and Bioinformatics and Department of Biology, Indiana University Bloomington, Indiana 47405, USA.
BMC Genomics. 2007 Dec 18;8:464. doi: 10.1186/1471-2164-8-464.
Sexual reproduction is a core biological function that is conserved throughout eukaryotic evolution, yet breeding systems are extremely variable. Genome-wide comparative studies can be effectively used to identify genes and regulatory patterns that are constrained to preserve core functions from those that may help to account for the diversity of animal reproductive strategies. We use a custom microarray to investigate gene expression in males and two reproductive stages of females in the crustacean Daphnia pulex. Most Daphnia species reproduce by cyclical parthenogenesis, alternating between sexual and clonal reproduction. Both sex determination and the switch in their mode of reproduction is environmentally induced, making Daphnia an interesting comparative system for the study of sex-biased and reproductive genes.
Patterns of gene expression in females and males reveal that 50% of assayed transcripts show some degree of sex-bias. Female-biased transcription is enriched for translation, metabolic and regulatory genes associated with development. Male-biased expression is enriched for cuticle and protease function. Comparison with well studied arthropods such as Drosophila melanogaster and Anopheles gambiae suggests that female-biased patterns tend to be conserved, whereas male-biased genes are evolving faster in D. pulex. These findings are based on the proportion of female-biased, male-biased, and unbiased genes that share sequence similarity with proteins in other animal genomes.
Some transcriptional differences between males and females appear to be conserved across Arthropoda, including the rapid evolution of male-biased genes which is observed in insects and now in a crustacean. Yet, novel patterns of male-biased gene expression are also uncovered. This study is an important first step towards a detailed understanding of the genetic basis and evolution of parthenogenesis, environmental sex determination, and adaptation to aquatic environments.
有性生殖是一项核心生物学功能，在整个真核生物进化过程中都得以保留，然而繁殖系统却极具多样性。全基因组比较研究可有效用于识别那些受限制以维持核心功能的基因和调控模式，以及那些可能有助于解释动物生殖策略多样性的基因和调控模式。我们使用定制微阵列来研究甲壳纲动物大型溞雄性以及雌性两个生殖阶段的基因表达。大多数大型溞物种通过周期性孤雌生殖进行繁殖，在有性生殖和克隆生殖之间交替。性别决定以及它们生殖模式的转变均受环境诱导，这使得大型溞成为研究性别偏向基因和生殖基因的一个有趣的比较系统。
雌性和雄性的基因表达模式表明，50%的检测转录本呈现出一定程度的性别偏向。雌性偏向转录在与发育相关的翻译、代谢和调控基因中富集。雄性偏向表达在表皮和蛋白酶功能方面富集。与果蝇和冈比亚按蚊等已得到充分研究的节肢动物进行比较表明，雌性偏向模式往往是保守的，而雄性偏向基因在大型溞中进化得更快。这些发现是基于与其他动物基因组中的蛋白质具有序列相似性的雌性偏向、雄性偏向和无偏向基因的比例得出的。
雄性和雌性之间的一些转录差异似乎在整个节肢动物门中都是保守的，包括在昆虫以及现在的一种甲壳纲动物中观察到的雄性偏向基因的快速进化。然而，也发现了雄性偏向基因表达的新模式。这项研究是朝着详细了解孤雌生殖、环境性别决定以及对水生环境的适应的遗传基础和进化迈出的重要第一步。
Zotero 插件
