Diverse sex determination mechanisms have been reported in eukaryotes, but little is known about the genetic pathways leading to sex determination in red algae. Sex‐specific genes that could be involved in sex determination and sexual differentiation were investigated in the red alga Bostrychia moritziana by analyzing the transcriptomes of various phases including males, females, and tetrasporophytes. Sex dominantly expressed genes which showed >10‐fold difference between sexes was isolated using comparative RNA‐seq analysis. We found 19 gene homologues, 10 from males, and nine from females, that were found only in one sex in genomic amplification using strains collected from five different localities. Most of the sex‐specific genes are involved in important cellular processes including chromosome segregation, nucleo‐cytoplasmic protein shuttling, or tRNA modification. Quantitative PCR analysis showed that some sex‐specific genes were differently regulated during critical events of sexual reproduction like fertilization and carposporophyte development. We could localize the expression of a male‐specific gene in spermatia before and after gamete binding using RNA in situ hybridization. Amino acid sequence identity between male and female homologues of importin alpha gene and PreQ(0) reductase were highly divergent (75% and 74%, respectively), suggesting that these divergent homologues are on non–recombining UV‐type chromosomes in their respective sexes. Another set of transcripts were found that were sex dominantly expressed, but not sex‐specific. Nineteen out of 39 sex dominantly expressed transcripts were annotated to transposable elements. Our results suggest that sexual differentiation in B. moritziana may be achieved by multi‐level regulation of cellular processes, both from genes present only in one sex and differential expression of shared genes.

中文翻译：

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特定性别的基因及其在红藻（Bostrychia moritziana）（Ceramiales，Rhodomelaceae）的生活史中的表达

真核生物中已经报道了多种性别决定机制，但是对导致红藻性别决定的遗传途径知之甚少。在红藻Bostrychia moritziana中研究了可能与性别决定和性别分化有关的性别特异性基因通过分析各个阶段的转录组，包括雄性，雌性和四孢子体。使用比较性RNA seq分析分离出显示出性别差异> 10倍的性别显性表达基因。我们发现使用从五个不同地区收集的菌株进行基因组扩增时，只有一种性别发现了19种基因同源物，其中10种来自雄性，而9种来自雌性。大多数具有性别特异性的基因都参与重要的细胞过程，包括染色体分离，核质蛋白穿梭或tRNA修饰。定量PCR分析表明，在性繁殖的关键事件（如受精和拟孢子体发育）中，某些性别特异性基因受到不同的调控。我们可以使用RNA原位杂交技术在配子结合之前和之后定位男性特异基因在精子中的表达。Importinα基因的男性和女性同源物与PreQ（0）还原酶之间的氨基酸序列同一性差异很大（分别为75％和74％），这表明这些差异同源物分别存在于各自性别的非重组UV型染色体上。发现另一组转录本以性别为主，但不是性别特异性的。在39个以性别为主的转录本中，有19个被注释为可转座因子。我们的研究结果表明，这表明这些不同的同源物在各自性别的非重组UV型染色体上。发现另一组转录本以性别为主，但不是性别特异性的。在39个以性别为主的转录本中，有19个被注释为可转座因子。我们的研究结果表明，这表明这些不同的同源物在各自性别的非重组UV型染色体上。发现另一组转录本以性别为主，但不是性别特异性的。在39个以性别为主的转录本中，有19个被注释为可转座因子。我们的研究结果表明，moritziana B. moritziana可以通过细胞过程的多级调节来实现，既可以来自仅存在于一种性别中的基因，也可以来自共享基因的差异表达。