The enzyme CYP17 primarily regulates androgen production by mediating four reactions: conversion of pregnenolone and progesterone to 17-hydroxypregnenolone and 17-hydroxyprogesterone, respectively (17alpha-hydroxylase activity), followed by conversion of the 17-hydroxylated steroids to dehydroepiandrosterone and androstenedione, respectively (17,20-lyase activity). Most mammalian CYP17 isoforms...

The germ cell nuclear factor (GCNF) is a nuclear orphan receptor and a putative regulator of the pluripotent state of cells. Although it was first described in mouse germ cells, GCNF is also expressed in mouse and Xenopus embryos. By means of 5'RACE we have identified a novel isoform of Xenopus laevis GCNF that is predominantly expressed in germ cells, whereas both the oocyte and embryonic form...

sarcoma.s in Triturus cristatus, and the experiments result ing in the induction of lymphosarcoma in Xenopus laevi@ laevis (2) have a number of similarities. Methylchol anth.rene as carcinogen and urethan as anesthetic are common features of these experiments, but whereas spontaneous lymphoid tumors are known in Xenopus, none have yet been reported in Triturus (1). Thus, the role of urethan in ...

Culture of lymphocytes from adult Xenopus laevis (Daudin) (a pipid anuran amphibian) with mitogens (PHA, ConA, LPS and PWM) reveals a wide variation in the mitogen sensitivity of these cells: relatively high concentrations of mitogen are required to stimulate Xenopus lymphocytes compared with the concentrations appropriate for mammalian lymphocytes. Significantly better responses are obtained u...

Injection of human Chorionic Gonadotropin (hCG) directly into the dorsal lymph sac of Xenopus is a commonly used protocol for induction of ovulation, but recent shortages in the stocks of commercially available hCG as well as lack of a well tested alternative have resulted in frustrating experimental delays in laboratories that predominantly use Xenopus in their research. Mammalian Luteinizing ...

Microtubule plus-end dynamics are regulated by a family of proteins called plus-end tracking proteins (+TIPs). We recently demonstrated that the transforming acidic coiled-coil (TACC) domain family member, TACC3, can function as a +TIP to regulate microtubule dynamics in Xenopus laevis embryonic cells. Although it has been previously reported that TACC3 is the only TACC family member that exist...

Xenopus ZFP36L1 (zinc finger protein 36, C3H type-like 1) belongs to the ZFP36 family of RNA-binding proteins, which contains two characteristic tandem CCCH-type zinc-finger domains. The ZFP36 proteins can bind AU-rich elements in 3' untranslated regions of target mRNAs and promote their turnover. However, the expression and role of ZFP36 genes during neural development in Xenopus embryos remai...

Bloom's syndrome (BS), a disorder associated with genomic instability and cancer predisposition, results from defects in the Bloom's helicase (BLM) protein. In BS cells, chromosomal abnormalities such as sister chromatid exchanges occur at highly elevated rates. Using Xenopus egg extracts, we have studied Xenopus BLM (Xblm) during both unperturbed and disrupted DNA replication cycles. Xblm bind...

BACKGROUND In Xenopus early embryogenesis, various genes are involved with mesoderm formation. In particular, dorsal mesoderm contains the organizer region and induces neural tissues through the inhibition of bone morphogenetic protein (BMP) signaling. In our initial study to identify novel genes necessary for maintaining the undifferentiated state, we unexpectedly revealed mesoderm-inducing ac...

Xenbase (www.xenbase.org), the model organism database for Xenopus laevis and X. (Silurana) tropicalis, is the principal centralized resource of genomic, development data and community information for Xenopus research. Recent improvements include the addition of the literature and interaction tabs to gene catalog pages. New content has been added including a section on gene expression patterns ...