Biomedical subjects

C A Rappleye

Publications and source records attributed to C A Rappleye.

4 recordsLinked to original sources

PubMed2001

Pod-2, along with pod-1, defines a new class of genes required for polarity in the early Caenorhabditis elegans embryo.

The asymmetric division of the one-cell Caenorhabditis elegans zygote gives rise to two cells of different size and fate, thereby establishing the animal's anterior--posterior (a-p) axis. Through genetics, a number of genes required for this polarity have been characterized, but many components remain unidentified. Recently, our laboratory discovered a mutation in the pod-1 gene (for polarity and osmotic defective) that uniquely perturbed polarity and osmotic protection. Here, we describe a new C. elegans polarity gene identified during screens for conditional embryonic lethals. Embryos in which this gene has been mutated show a loss of physical and developmental asymmetries in the one-cell embryo, including the mislocalization of PAR and POD-1 proteins required for early polarity. Furthermore, mutant embryos are osmotically sensitive, allowing us to designate this gene pod-2. Thus, pod-2, along with pod-1, defines a new class of C. elegans polarity genes. Genetic analyses indicate that pod-2 functions in the same pathway as pod-1. Temperature-shift studies indicate that pod-2 is required during oogenesis, indicating that aspects of embryonic polarization may precede fertilization. pod-2 mutant embryos also exhibit a unique germline inheritance defect in which germline identity localizes to the wrong spot in the one-cell embryo and is therefore inherited by the wrong cell at the four-cell stage. Our data suggest that pod-2 may be required to properly position an a-p polarity cue.

Alleles↗

PubMed1999

The coronin-like protein POD-1 is required for anterior-posterior axis formation and cellular architecture in the nematode caenorhabditis elegans.

Establishment of anterior-posterior (a-p) polarity in the Caenorhabditis elegans embryo depends on filamentous (F-) actin. Previously, we isolated an F-actin-binding protein that was enriched in the anterior cortex of the one-cell embryo and was hypothesized to link developmental polarity to the actin cytoskeleton. Here, we identify this protein, POD-1, as a new member of the coronin family of actin-binding proteins. We have generated a deletion within the pod-1 gene. Elimination of POD-1 from early embryos results in a loss of physical and molecular asymmetries along the a-p axis. For example, PAR-1 and PAR-3, which themselves are polarized and required for a-p polarity, are delocalized in pod-1 mutant embryos. However, unlike loss of PAR proteins, loss of POD-1 gives rise to the formation of abnormal cellular structures, namely large vesicles of endocytic origin, membrane protrusions, unstable cell divisions, a defective eggshell, and deposition of extracellular material. We conclude that, analogous to coronin, POD-1 plays an important role in intracellular trafficking and organizing specific aspects of the actin cytoskeleton. We propose models to explain how the role of POD-1 in basic cellular processes could be linked to the generation of polarity along the embryonic a-p axis.

Actins↗

PubMed1997

A Tn10 derivative (T-POP) for isolation of insertions with conditional (tetracycline-dependent) phenotypes.

A new Tn10-based transposon has been constructed and used to isolate insertion mutations with tetracycline-conditional phenotypes. Classes of mutants include conditional lethal mutations, conditional auxotrophs, and conditional mutants of the eut (ethanolamine utilization) operon. The described mutations were made with a new derivative of Tn10dTet that we have called Tn10d(T-POP). Others have noted that transposon Tn10dTet directs weak tetracycline-inducible transcripts out of both ends of the element into adjacent sequences. We have increased this level of outward transcription from Tn10dTet by selecting deletion mutations within the element that presumably remove transcription-termination signals. Insertion of the Tn10d(T-POP) element within an operon disrupts the target gene and makes expression of distal genes dependent on induction of outward transcription by tetracycline. Insertion mutations made with Tn10d(T-POP) can cause tetracycline-correctable conditional phenotypes based on expression of distal genes.

Antiporters↗

PubMed1997

Transposition without transposase: a spontaneous mutation in bacteria.

Transposition mutations are typically associated with the activities of transposable elements such as transposons and insertion sequences, whose mobility is dependent upon transposase enzymes that catalyze exchanges between element ends and target sites. We describe a single transposition event in which a block of donor sequence is inserted at a target site without the involvement of any known transposase or the ends of any known transposable element. We propose that this is a new type of spontaneous mutation which may be difficult to detect in standard mutant hunts but may be of evolutionary importance.

DNA Nucleotidyltransferases↗