Gene expression in the embryonic nervous system of Xenopus laevis.

Abstract

Development of the nervous system in the amphibian embryo is initiated during gastrulation by an inductive interaction between chordamesoderm and dorsal ectoderm. The induced ectoderm forms the neural plate while uninduced ectoderm generates epidermis. We screened for genes activated during gastrulation and expressed specifically in the nervous system of Xenopus laevis in the expectation that clones representing such genes will constitute useful markers for the study of early neurogenesis. Probes were prepared from adult brain RNA by subtraction with RNA from ovary and from different combifnations of adult kidney, muscle, and skin; cDNA libraries prepared from early to late neurula embryo RNA were screened with these probes. Six clones were chosen for further study. Three of these clones are not represented in the maternal RNA population but are activated at the late gastrula stage; the other three increase from a maternal base. Expression of five of the genes is restricted to the neural plate during embryogenesis, and all six are restricted to the central nervous system in premetamorphic tadpoles and adults. One of the clones encodes an apparently neurospecific isoform of f8-tubulin; the identity of the other clones is unknown. Expression of all six genes is suppressed in axis-deficient embryos that lack dorsal structures including the brain.Neural induction triggers the development of the nervous system, one of the first stages of tissue differentiation in the vertebrate embryo. The nature of the neural induction signal has been a challenging problem since the time ofthe Spemann and Mangold experiment (1) in which the phenomenon of induction was discovered. These authors transplanted the dorsal blastopore lip from one embryo into the ventral region of another and showed that this transplant was able to induce a second body axis including a second nervous system. In

Functional expression of N‐terminal truncated α‐subunits of Na,K‐ATPase in Xenopus laevis oocytes

“…The near full-length a, cDNA (-45 to +3349 bp = &wt) from Xcnopus laevis previously cloned from an A6 kidney cell library [9] and a /3x cDNA cloned from a Xenopus neurula library [7,8] were inserted into the pSDS vector [6]. We have previously shown that both the PI September 1991 Fig.…”

The Ca 2 +-induced methyltransferase xPRMT1b controls neural fate in amphibian embryo

“…17. Antisense probes labeled with digoxigenin were synthesized by using cDNA templates encoding Zic3 (18), Xbra (19), N-tubulin (20), and En2 (21). For xPRMT1b ISH, we used the fragment 3E10, located in the 3ЈUTR of xPRMT1b.…”

Xmeis1, a protooncogene involved in specifying neural crest cell fate in Xenopus embryos

“…Plasmids containing N-tubulin (Richter et al, 1988), Xenopus Krox-20 (Bradley et al, 1993), Xenopus Ap-2 (Winning et al, 1991), Xenopus Slug (Mayor et al, 1995), Xenopus Zic3 (Nakata et al, 1997), and Xenopus type I keratin (Miyatani et al, 1986) were linearized with restriction enzymes (StuI for N-tubulin, EcoRI for XKrox-20, HindIII for Xap-2, EcoRI for XSlug, BamHI for XZic3, and EcoRI for Xkeratin), and digoxygenin-labeled riboprobes were synthesized using T3 (for N-tubulinand XZic3) or T7 (for XKrox-20, Xap-2, and XSlug) or SP6 (for Xkeratin) polymerase. Wholemount in situ hybridization was essentially done as described by Harland (1991).…”