A molecular network of conserved factors keeps ribosomes dormant in the egg.

Ribosomes are produced in large quantities during oogenesis and are stored in the egg. However, the egg and early embryo are translationally repressed. Here, using mass spectrometry and cryo-electron microscopy analyses of ribosomes isolated from zebrafish (Danio rerio) and Xenopus laevis eggs and embryos, we provide molecular evidence that ribosomes transition from a dormant state to an active state during the first hours of embryogenesis.

Inducible and tissue-specific cell labeling in Cre-ER transgenic Xenopus lines.

Investigating cell lineage requires genetic tools that label cells in a temporal and tissue-specific manner. The bacteriophage-derived Cre-ER /loxP system has been developed as a genetic tool for lineage tracing in many organisms. We recently reported a stable transgenic Xenopus line with a Cre-ER /loxP system driven by the mouse Prrx1 (mPrrx1) enhancer to trace limb fibroblasts during the regeneration process (Prrx1:CreER line).

Fibroblast dedifferentiation as a determinant of successful regeneration.

Limb regeneration, while observed lifelong in salamanders, is restricted in post-metamorphic Xenopus laevis frogs. Whether this loss is due to systemic factors or an intrinsic incapability of cells to form competent stem cells has been unclear. Here, we use genetic fate mapping to establish that connective tissue (CT) cells form the post-metamorphic frog blastema, as in the case of axolotls.

Differential efficacy of genetically swapping GAL4.

Several large or mid-scale collections of enhancer traps have been recently created to allow for genetic swapping of GAL4 coding sequences to versatile transcription activators or suppressors such as LexA, QF, split-GAL4 (GAL4-AD and GAL4-DBD), GAL80 and QS. Yet a systematic analysis of the feasibility and reproducibility of these tools is lacking. Here we focused on InSITE drivers that specifically label different subpopulations of olfactory neurons, particularly local interneurons (LNs), and genetically swapped the GAL4 domain for LexA, GAL80 or QF at the same locus.

Diverse populations of local interneurons integrate into the Drosophila adult olfactory circuit.

Drosophila olfactory local interneurons (LNs) in the antennal lobe are highly diverse and variable. How and when distinct types of LNs emerge, differentiate, and integrate into the olfactory circuit is unknown. Through systematic developmental analyses, we found that LNs are recruited to the adult olfactory circuit in three groups.

Differential expression and functional analysis of the tristetraprolin family during early differentiation of 3T3-L1 preadipocytes.

The tristetraprolin (TTP) family comprises zinc finger-containing AU-rich element (ARE)-binding proteins consisting of three major members: TTP, ZFP36L1, and ZFP36L2. The present study generated specific antibodies against each TTP member to evaluate its expression during differentiation of 3T3-L1 preadipocytes. In contrast to the inducible expression of TTP, results indicated constitutive expression of ZFP36L1 and ZFP36L2 in 3T3-L1 preadipocytes and their phosphorylation in response to differentiation signals.