Understanding the origin of parthenogenesis

了解孤雌生殖的起源

基本信息

批准号：
10874028
负责人：
Sen Xu
金额：
$ 37.27万
依托单位：
UNIVERSITY OF MISSOURI-COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-07-01 至 2024-06-30
项目状态：
已结题

项目摘要

Project Summary Parthenogenesis (i.e., reproduction without mating) has evolved from sexual reproduction in nearly all major eukaryotic groups. In parthenogenesis, chromosomally unreduced (e.g., diploid) gametes result from modified forms of meiosis. Understanding the genetic mechanisms underlying the modification of meiosis in parthenogenetic lineages is of significant public health interest because meiosis is central to sexual reproduction. Using parthenogenesis to understand the genetic regulation of meiosis is also a highly innovative approach, with its natural history perspective most likely yielding novel knowledge about meiosis. Using a combination of evolutionary and functional genomic approaches, this project examines the genetic bases of cyclical and obligate parthenogenesis in the freshwater microcrustacean Daphnia, which represents an excellent tractable experimental system with well-understood biology and many genomic tools. Daphnia is well known for its cyclical parthenogenesis (CP) life cycle, i.e., propagating asexually under favorable environmental conditions and switching to sexual reproduction in response to stressful environment. Interestingly, some populations of the species D. pulex (backcrosses of two parental CP species D. pulex and D. pulicaria) reproduce by obligate parthenogenesis (OP) because they lost the capability to engage in sex. This project has two long-term goals. First, considering that a single Daphnia genome can encode the genetic machinery for both reproductive strategies, it is hypothesized that environment-mediated gene expression changes, especially the neofunctionalization of duplicated meiosis genes (e.g. Cdc20), play a role in the origin of CP. To test this, ovary- specific gene expression changes between parthenogenesis and meiosis in CP D. pulex and D. pulicaria will be examined to produce a high quality set of candidate genes. To determine the functional role of these candidates in CP (e.g., master regulator genes), we will perform RNAi knockdown of each candidate in CP isolates and examine the associated phenotypic effects using animal reproduction assay and cytological examination of developing oocytes. Second, concerning the origin of OP, we hypothesize that the genetic incompatibility between the two ecologically divergent species CP D. pulex and D. pulicaria is a key factor. For the previously identified candidate genes for OP, we will test (1) whether they experience differential gene expression in OP isolates compared to CP isolates and (2) whether their expression is mis-regulated (i.e., genetic incompatibility). The former will be achieved by ovary-specific RNA-seq in OP and CP clones at different reproductive stages, whereas the latter will be based on allele-specific RNA-seq analysis of the parental species and OP isolates. For the candidate genes showing differential expression and mis-regulation, RNAi knockdown and phenotype screening will be performed to verify their functional role in OP, whereas CRISPR/Cas9 editing will be used to identify the causal SNPs for each gene. Lastly, we will re-create OP animals by introducing OP-causal SNPs to CP Daphnia pulex using CRISPR/Cas9 editing.

项目摘要孤苯二酚发生（即，不交配而无需交配），几乎在所有主要的真核生物群。在单性生殖中，染色体未还原（例如，二倍体）配子是由修饰的减数分裂的形式。了解减数分裂修饰的遗传机制孤态发育谱系具有重大的公共卫生兴趣，因为减数分裂对于有性繁殖至关重要。利用孤苯甲生成来了解减数分裂的遗传调节也是一种高度创新的方法，它的自然历史观点最有可能产生有关减数分裂的新知识。结合进化和功能性基因组方法，该项目研究了周期性和义务的遗传基础淡水微透质水坝中的孤子发生，这代表了极好的可牵引力实验系统具有良好的生物学和许多基因组工具。水煮者以其周期性而闻名对孤苯甲生成（CP）生命周期，即在有利的环境条件下无性繁殖和转向有性繁殖，以应对压力的环境。有趣的是，一些人口物种D. pulex（两个父母CP物种的反杂交D. pulex和D. pulicaria）繁殖孤雌生成（OP）是因为他们失去了从事性行为的能力。该项目有两个长期目标。首先，考虑到单个水坝基因组可以编码两种生殖的遗传机制策略，假设环境介导的基因表达变化，尤其是重复的减数分裂基因（例如CDC20）的新功能化在CP的起源中起作用。为了测试这一点，卵巢 - 特定的基因表达在Cp D. pulex和D. pulicaria中的孤雌生成和减数分裂之间的变化将是检查以产生高质量的候选基因。确定这些候选人的功能作用在CP（例如主调节基因）中，我们将在CP分离株和使用动物繁殖试验和细胞学检查检查相关的表型效应发展卵母细胞。其次，关于OP的起源，我们假设遗传不相容性在两个生态上不同的物种Cp D. Pulex和D. pulicaria之间是关键因素。对于以前的确定的OP候选基因，我们将测试（1）它们是否在OP中经历差异基因表达与CP分离株相比，分离株和（2）它们的表达是否被错误调节（即遗传不相容性）。前者将通过OP中的卵巢特异性RNA-seq在不同的生殖阶段实现，而后者将基于对父母物种和OP分离株的等位基因特异性RNA-seq分析。为了候选基因表达差异表达和失调，RNAi敲低和表型将进行筛选以验证其在OP中的功能作用，而CRISPR/CAS9编辑将用于确定每个基因的因果SNP。最后，我们将通过将op-ausal snps引入到 CP Daphnia pulex使用CRISPR/CAS9编辑。

项目成果

期刊论文数量（11）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Delivery methods for CRISPR/Cas9 gene editing in crustaceans.

DOI：
10.1007/s42995-019-00011-4
发表时间：
2020-02
期刊：
Marine life science & technology
影响因子：
5.7
作者：
Xu S;Pham T;Neupane S
通讯作者：
Neupane S

The Transcriptomic Signature of Cyclical Parthenogenesis.

DOI：
10.1093/gbe/evad122
发表时间：
2023-07-03
期刊：
GENOME BIOLOGY AND EVOLUTION
影响因子：
3.3
作者：
Huynh, Trung Viet;Hall, Alexander S.;Xu, Sen
通讯作者：
Xu, Sen

Attachment and Release of Water Fleas' Ephippia on a Medium-Sized Waterfowl's Leg for Migration.

水蚤 Ephippia 在中型水禽腿上的附着和释放以进行迁徙。

DOI：
10.1021/acs.langmuir.3c01563
发表时间：
2023
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
0
作者：
Wang,Xiang;Xu,Sen;Luo,Cheng
通讯作者：
Luo,Cheng

An efficient method for hatching diapausing embryos of Daphnia pulex species complex (Crustacea, Anomopoda).

孵化水溞物种复合体（甲壳纲、无足纲）滞育胚胎的有效方法。

DOI：
10.1002/jez.2331
发表时间：
2020
期刊：
Journal of experimental zoology. Part A, Ecological and integrative physiology
影响因子：
0
作者：
Luu,DustinH-K;Vo,HillaryP;Xu,Sen
通讯作者：
Xu,Sen

The life-history fitness of F1 hybrids of the microcrustacean Daphnia pulex and D. pulicaria (Crustacea, Anomopoda).

微甲壳动物 Daphnia pulex 和 D. pulicaria（甲壳纲，Anomopoda）的 F1 杂交种的生活史适应性。