Maternal factors in zebrafish development

Abstract

All processes that occur before the activation of the zygotic genome at the midblastula transition are driven by maternal products, which are produced during oogenesis and stored in the mature oocyte. Upon egg activation and fertilization, these maternal factors initiate developmental cascades that carry out the embryonic developmental program. Even after the initiation of zygotic gene expression, perduring maternal products continue performing essential functions, either together with other maternal factors or through interactions with newly expressed zygotic products. Advances in zebrafish research have placed this organism in a unique position to contribute to a detailed understanding of the role of maternal factors in early vertebrate development. This review summarizes our knowledge on the processes involved in the production and redistribution of maternal factors during zebrafish oogenesis and early development, as well as our understanding of the function of these factors in axis formation, germ layer and germ cell specification, and other early embryonic processes. Developmental Dynamics 228:535-554, 2003.

Insulin-like growth factor signaling regulates zebrafish embryonic growth and development by promoting cell survival and cell cycle progression

“…The finding that IGF1R-deficient embryos progressed normally through development until approximately 16 hpf and then arrested at 18 hpf is both intriguing and puzzling, because both IGF ligands and IGF1Rs are expressed in a widespread fashion throughout all stages of embryogenesis. 14 Because it is known that maternal proteins can influence early development in zebrafish, 22 we postulated that maternal IGF1R protein may keep normal development up to 16 hpf. To test this idea and to investigate the developmental roles of IGF1R signaling further using an independent approach, a zebrafish dominant-negative IGF1R was constructed by deleting the intracellular signaling domain of IGF1Ra and tagging its C terminus with EGFP (dnIGF1R:GFP) ( Figure 5a).…”

Identification of a Spindlin homolog in gibel carp (Carassius auratus gibelio)

“…Upon egg activation and fertilization, these maternal factors initiate developmental cascades that carry out the embryonic developmental program (Pelegri, 2003). In zebrafish, midblastula transition occurs at the 512-cell stage (Kane and Kimmel, 1993), and is characterized by a loss of cell division synchrony, an increase in cell motility, and the onset of wholesale zygotic transcription (Newport and .…”

The knockdown of maternal glucocorticoid receptor mRNA alters embryo development in zebrafish

“…Similarly to other fish, zebrafish early oocytes contain a powerful and complex transcriptional machinery that, during the diplotene stage of meiosis I, transcribes in loops of lampbrush chromosomes a large part of the entire genome to sustain vitellogenic growth, preovulatory maturation, perifertilization activation, and early embryogenesis (Pelegri, 2003). For the last purpose, mRNAs are preserved from degradation by translational repression, for instance by deadenylation upon nuclear transport and readenylayion at ovulation (see review by Farley and Ryder, 2008).…”

“…Our WMISH analysis clearly demonstrates that maternal gr mRNA in ovulated oocytes is diffuse throughout the central ooplasm as many small granules and filaments. Several mechanisms have been proposed for the confluence of different ooplasmic mRNAs towards the yolkfree animal pole, whenever they are not already there, ranging from tethered transport by cytoskeletal components to passive diffusion along interphasic ooplasmic streaming up to the 6th cleavage cycle (2 hpf) (Pelegri, 2003). Transport of most gr mRNA by streamers was evidenced by WMISH analysis already in 1-cell zygote (0.2 hpf), but cytoskeletal vectors remain a possibility owing to the thread arrangement of the message.…”