Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs

Abstract

Protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs Engystomops randi, Epipedobates machalilla, Gastrotheca riobambae, and Eleutherodactylus coqui, as in Xenopus laevis embryos. Protein VegT was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was VegT-negative. This finding stimulated a vegt mRNA analysis in X. laevis eggs and embryos. vegt mRNA was detected in the animal region of X. laevis eggs and early embryos, in agreement with the VegT localization observed in the analyzed frogs. Moreover, a dorso-animal relocalization of vegt mRNA occurred in the egg at fertilization. Thus, the comparative analysis indicated that vegt may participate in dorsal development besides its known roles in endoderm development, and germlayer specification. Zygotic vegt (zvegt) mRNA was detected as a minor isoform besides the major maternal (mvegt) isoform of the X. laevis egg. In addition, α-amanitin-insensitive vegt transcripts were detected around vegetal nuclei of the blastula. Thus, accumulation of vegt mRNA around vegetal nuclei was caused by relocalization rather than new mRNA synthesis. The localization of vegt mRNA around vegetal nuclei may contribute to the identity of vegetal blastomeres. These and previously reportedly localization features of vegt mRNA and protein derive from the master role of vegt in the development of frogs. The comparative analysis indicated that the strategies for endoderm, and dorsal specification, involving vegt and mix1, have been evolutionary conserved in frogs.mvegt | zvegt | germ plasm | blastula | gastrula

Cell cycle length regulates heterochromatin reprogramming during early development in non-mammalian vertebrates

“…As in medaka and zebrafish, H3K9me3 levels gradually increase during the MBT in Xenopus (Fig 6A-C). As previously reported (Sudou et al , 2016; Chen et al , 2019), blocking ZGA by α-amanitin injection resulted in developmental arrest, and injected embryos did not undergo gastrulation (Fig 6D). We tested the requirement of ZGA for H3K9me3 accumulation, but we did not find statistically significant differences in H3K9me3 levels between control and α-amanitin-injected embryos at the stage 10 (the onset of gastrulation) (Fig 6 B, C).…”

“…Developmental stages were determined according to previously published guidelines (Nieuwkoop & Faber, 1994) (Fig 6A). At the two-cell stage, 100pg α-amanitin (Sudou et al , 2016; Chen et al , 2019) and 200 pg medaka chk1 mRNA were injected into each blastomere. Embryos were incubated with 20 ng/µL CHX from the 64-cell stage.…”

Developmental Biology in Central America, the northern region of South America and the Caribbean

“…I will not dwell on her many studies using these organisms, since they are best described in the accompanying autobiography in this issue (Del Pino in this issue). Nonetheless, it is important to highlight that her studies went beyond the development of the frogs (see Del Pino et al 2004Pino et al , 2007 covering many other areas, including oogenesis (Del Pino et al 1986), metabolism (Alcocer et al 1992, in vitro systems (Del Pino et al 1994), and more recently molecular studies (Benítez and Del Pino 2002, Venegas-Ferrín et al 2010, Sudou et al 2016. Equally important to the advance of DB in the region has been her involvement in the training of students, keeping collaborations with established scientists at top universities who not only participate in the ongoing research projects but also visit Latin-America for seminars and workshops (Del Pino 2003).…”

RNA Localization in the Vertebrate Oocyte: Establishment of Oocyte Polarity and Localized mRNA Assemblages

“…All of these RNAs appear to be able to localize through the late pathway (Zhang and King 1996; Le Goff et al 2006; Cuykendall and Houston 2009), although dnd1 , trim36 , and spire1 likely belong to the “intermediate” class of localized RNAs since they also preferentially accumulate in the germ plasm (Horvay et al 2006; Le Goff et al 2006; Cuykendall and Houston 2009). Interestingly, vegt mRNA can also accumulate somewhat in the germ plasm (Sudou et al 2016), suggesting that many localizing RNAs may have this property, possibly through nonspecific RNP droplet association. Curiously, vegt undergoes a “relocalization” during the cleavage stages and becomes enriched dorsoanimally and accumulates around vegetal nuclei (Sudou et al 2016), although the specificity and significance of this behavior is unclear.…”

“…Interestingly, vegt mRNA can also accumulate somewhat in the germ plasm (Sudou et al 2016), suggesting that many localizing RNAs may have this property, possibly through nonspecific RNP droplet association. Curiously, vegt undergoes a “relocalization” during the cleavage stages and becomes enriched dorsoanimally and accumulates around vegetal nuclei (Sudou et al 2016), although the specificity and significance of this behavior is unclear.…”