Department of Marine Biology and Ecology, Institute of Oceanography, Faculty of Oceanography and Geography, University of Gdansk, Al. M. Piłsudskiego 46, 81-378, Gdynia, Poland.
Fish Physiol Biochem. 2024 Oct;50(5):1947-1957. doi: 10.1007/s10695-023-01206-4. Epub 2023 Jun 10.
Induced development of haploid embryos (H) with only paternal (androgenesis) or maternal (gynogenesis) chromosomes requires irradiation of eggs before fertilization or activation of eggs with irradiated spermatozoa, respectively. To provide doubled haploids (DHs), androgenetic and gynogenetic haploid zygotes need to be subjected to the thermal or high hydrostatic pressure (HHP) shock to suppress the first mitotic cleavage and to double paternal or maternal haploid set of chromosomes. Androgenesis and mitotic gynogenesis (mito-gynogenesis) result in the generation of fully homozygous individuals in a single generation. DHs have been utilized in selective breeding programs, in studies concerning the phenotypic consequences of recessive alleles and to evaluate the impact of sex chromosomes on the early ontogeny. Moreover, the use of DHs for the NGS approach radically improves de novo the assembly of the genomes. However, reduced survival of the doubled haploids limits the wide application of androgenotes and gynogenotes. The high mortality of DHs may be only partly explained by the expression of recessive traits. Observed inter-clutch variation in the survival of DHs developing in eggs originating from different females make it necessary to take a closer look at the quality of the eggs used during induced androgenesis and gynogenesis. Moreover, the developmental competence of eggs that are subjected to irradiation before fertilization in order to deactivate maternal chromosomes when undergoing induced androgenesis and exposed to the physical shock after fertilization that leads to the duplication of the zygotes in both mito-gynogenesis and androgenesis may be also altered as irradiation and sublethal values of temperatures and hydrostatic pressure are considered as harmful for the cell organelles and biomolecules. Here, recently provided results concerning the morphological, biochemical, genomic, and transcriptomic characteristics of fish eggs showing high and low competence for androgenesis and mito-gynogenesis are reviewed.
诱导单倍体胚胎(H)的发育,这些胚胎只有父本(雄性生殖)或母本(雌性生殖)染色体,需要在受精前对卵子进行照射,或分别用照射过的精子激活卵子。为了提供双倍单倍体(DH),需要对雄性生殖和雌性生殖的单倍体受精卵进行热或高静水压力(HHP)休克处理,以抑制第一次有丝分裂分裂,并使父本或母本的单倍体染色体加倍。雄性生殖和有丝分裂雌性生殖(mito-gynogenesis)导致在一个单一代中产生完全纯合的个体。DH 已被用于选择育种计划,研究隐性等位基因的表型后果,并评估性染色体对早期胚胎发生的影响。此外,使用 DH 进行 NGS 方法可以从根本上提高基因组的从头组装。然而,双倍单倍体的存活率降低限制了雄性生殖体和雌性生殖体的广泛应用。DHs 的高死亡率可能仅部分归因于隐性性状的表达。在来自不同雌性的卵子中发育的 DHs 的存活率存在观察到的窝间变异性,这使得有必要仔细研究在诱导雄性生殖和雌性生殖中使用的卵子质量。此外,在受精前进行照射以在诱导雄性生殖时使母本染色体失活,并且在受精后进行物理冲击以在有丝分裂雌性生殖和雄性生殖中使受精卵加倍的卵子的发育能力也可能发生改变,因为照射和亚致死温度和静水压力值被认为对细胞器和生物分子有害。在这里,最近提供了关于在诱导雄性生殖和有丝分裂雌性生殖中表现出高和低能力的鱼类卵子的形态、生化、基因组和转录组特征的结果。