Post-Diapause DNA Replication during Oogenesis in a Capital-Breeding Copepod.
Post-Diapause DNA Replication during Oogenesis in a Capital-Breeding Copepod.
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DOI：
10.1093/iob/obad020
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发表时间：
2023
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影响因子：
--
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中科院分区：
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在高纬度环境中，季节变化包括恶劣条件的时期，许多节肢动物进入滞育，这是一个受季节调节的休眠期。滞育的特征是代谢非常低，对环境胁迫的抵抗力和发育停滞。它允许生物体通过使后代的生长和发育与高食物可用性时期同步来优化繁殖时间。在进入休眠期的物种中，滞育的终止标志着生理过程的恢复，代谢率的增加，一旦雌性过渡到成年期，卵子发生的开始。在许多情况下，个体再次开始进食，新获得的资源可用于促进鸡蛋生产。然而，在亚北极首都繁殖桡足类新哲水蚤flemingeri，喂养是脱钩卵子发生。因此，为了优化受固定资源限制的繁殖，使所有卵子都具有高质量和充分供应，需要调节卵母细胞的数量。然而，目前还不清楚这种桡足类是否以及如何限制卵母细胞的形成。本研究采用5-乙炔基-2 ′-脱氧尿苷（EdU）孵育法，研究了滞育后雌虫卵母细胞产生过程中涉及卵巢和输卵管DNA复制的阶段。卵原细胞和卵母细胞纳入EdU，与EdU标记的细胞的数量在滞育终止后72小时达到峰值。细胞标记与EdU保持高的两个星期，减少之后没有标记检测到的4周后滞育，和3至4周前产卵的第一窝卵。结果表明，N.新卵母细胞在滞育终止后24小时内开始形成，并仅限于最初几周。滞育期间的脂质消耗是最小的，最初相对温和。这一生殖程序的早期阶段先于中期卵子发生和卵黄发生2，此时卵母细胞的大小增加，并积累卵黄和脂质储备。通过将DNA复制限制在初始阶段，雌性有效地将卵母细胞生产与卵母细胞供应分开。顺序卵子发生不同于大多数桡足类的收入繁殖策略，在这种策略中，在所有成熟阶段的卵母细胞都同时存在于生殖结构中。
In high-latitude environments where seasonal changes include periods of harsh conditions, many arthropods enter diapause, a period of dormancy that is hormonally regulated. Diapause is characterized by very low metabolism, resistance to environmental stress, and developmental arrest. It allows an organism to optimize the timing of reproduction by synchronizing offspring growth and development with periods of high food availability. In species that enter dormancy as pre-adults or adults, termination of diapause is marked by the resumption of physiological processes, an increase in metabolic rates and once transitioned into adulthood for females, the initiation of oogenesis. In many cases, individuals start feeding again and newly acquired resources become available to fuel egg production. However, in the subarctic capital-breeding copepod Neocalanus flemingeri, feeding is decoupled from oogenesis. Thus, optimizing reproduction limited by fixed resources such that all eggs are of high quality and fully-provisioned, requires regulation of the number of oocytes. However, it is unknown if and how this copepod limits oocyte formation. In this study, the phase in oocyte production by post-diapause females that involved DNA replication in the ovary and oviducts was examined using incubation in 5-Ethynyl-2′-deoxyuridine (EdU). Both oogonia and oocytes incorporated EdU, with the number of EdU-labeled cells peaking at 72 hours following diapause termination. Cell labeling with EdU remained high for two weeks, decreasing thereafter with no labeling detected by four weeks post diapause, and three to four weeks before spawning of the first clutch of eggs. The results suggest that oogenesis is sequential in N. flemingeri with formation of new oocytes starting within 24 hours of diapause termination and limited to the first few weeks. Lipid consumption during diapause was minimal and relatively modest initially. This early phase in the reproductive program precedes mid-oogenesis and vitellogenesis 2, when oocytes increase in size and accumulate yolk and lipid reserves. By limiting DNA replication to the initial phase, the females effectively separate oocyte production from oocyte provisioning. A sequential oogenesis is unlike the income-breeder strategy of most copepods in which oocytes at all stages of maturation are found concurrently in the reproductive structures.
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影响因子：
2.6
作者：
Cooney, RT;Coyle, KO;Stark, C
通讯作者：
Stark, C
影响因子：
2.6
作者：
Coyle, KO;Pinchuk, AI
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Pinchuk, AI
影响因子：
3.4
作者：
Beltz, Barbara S.;Zhang, Yi;Sandeman, David C.
通讯作者：
Sandeman, David C.
影响因子：
2.8
作者：
Coyle, K. O.;Gibson, G. A.;Hopcroft, R. R.
通讯作者：
Hopcroft, R. R.
影响因子：
2.5
作者：
HIRCHE, HJ
通讯作者：
HIRCHE, HJ