Identification of novel synaptonemal complex components in C. elegans.

The synaptonemal complex (SC) is a tripartite protein scaffold that forms between homologous chromosomes during meiosis. Although the SC is essential for stable homologue pairing and crossover recombination in diverse eukaryotes, it is unknown how individual components assemble into the highly conserved SC structure. Here we report the biochemical identification of two new SC components, SYP-5 and SYP-6, in Caenorhabditis elegans.

Superresolution imaging of chromatin fibers to visualize epigenetic information on replicative DNA.

During DNA replication, the genetic information of a cell is copied. Subsequently, identical genetic information is segregated reliably to the two daughter cells through cell division. Meanwhile, DNA replication is intrinsically linked to the process of chromatin duplication, which is required for regulating gene expression and establishing cell identities.

Asymmetric histone inheritance via strand-specific incorporation and biased replication fork movement.

Many stem cells undergo asymmetric division to produce a self-renewing stem cell and a differentiating daughter cell. Here we show that, similarly to H3, histone H4 is inherited asymmetrically in Drosophila melanogaster male germline stem cells undergoing asymmetric division. In contrast, both H2A and H2B are inherited symmetrically.

Toxic PR poly-dipeptides encoded by the repeat expansion block nuclear import and export.

The toxic proline:arginine (PR) poly-dipeptide encoded by the (GGGGCC) repeat expansion in the form of heritable amyotrophic lateral sclerosis (ALS) binds to the central channel of the nuclear pore and inhibits the movement of macromolecules into and out of the nucleus. The PR poly-dipeptide binds to polymeric forms of the phenylalanine:glycine (FG) repeat domain, which is shared by several proteins of the nuclear pore complex, including those in the central channel. A method of chemical footprinting was used to characterize labile, cross-β polymers formed from the FG domain of the Nup54 protein.

Isolation of Giant Lampbrush Chromosomes from Living Oocytes of Frogs and Salamanders.

We describe methods for studying the giant transcriptionally active lampbrush chromosomes (LBCs) found in the oocyte, or unlaid egg, of frogs and salamanders. Individual LBCs can be up to 1 mm in length and they reside in a gigantic nucleus, itself up to 0.5 mm in diameter.

Fluorescent In Situ Hybridization of Nuclear Bodies in Drosophila melanogaster Ovaries.

Fluorescent in situ hybridization (FISH) is a technique for determining the cytological localization of RNA or DNA molecules. There are many approaches available for generating in situ hybridization probes and conducting the subsequent hybridization steps. Here, we describe a simple and reliable FISH method to label small RNAs (200-500 nucleotides in length) that are enriched in nuclear bodies in Drosophila melanogaster ovaries, such as Cajal bodies (CBs) and histone locus bodies (HLBs).

A remarkable career in science-Joseph G. Gall.

A festive group of ∼150 current and former students, postdoctoral and other associates, and colleagues gathered during the weekend of April 12-14, 2013 to celebrate Joe Gall's 85th birthday. The gathering, hosted by the Carnegie Institution for Science, Department of Embryology (Allan Spradling, Director) and organized by a group of Joe's current and former students (Zehra Nizami, Alison Singer, Ji-Long Liu, Virginia Zakian, Susan Gerbi), was held in Baltimore, MD. Dinners and symposia extending over 3 days celebrated Joe's scientific findings over the years, together with those of his former students, postdoctoral fellows, and other associates (see program at https://sites.

Stable intronic sequence RNA (sisRNA), a new class of noncoding RNA from the oocyte nucleus of Xenopus tropicalis.

To compare nuclear and cytoplasmic RNA from a single cell type, free of cross-contamination, we studied the oocyte of the frog Xenopus tropicalis, a giant cell with an equally giant nucleus. We isolated RNA from manually dissected nuclei and cytoplasm of mature oocytes and subjected it to deep sequencing. Cytoplasmic mRNA consisted primarily of spliced exons derived from ∼6700 annotated genes.

Pearls are novel Cajal body-like structures in the Xenopus germinal vesicle that are dependent on RNA pol III transcription.

We have identified novel nuclear bodies, which we call pearls, in the giant oocyte nuclei of Xenopus laevis and Xenopus tropicalis. Pearls are attached to the lampbrush chromosomes at specific loci that are transcribed by RNA polymerase III, and they disappear after inhibition of polymerase III activity. Pearls are enriched for small Cajal body-specific RNAs (scaRNAs), which are guide RNAs that modify specific nucleotides on splicing snRNAs.

The Cajal body and histone locus body.

The Cajal body (CB) is a nuclear organelle present in all eukaryotes that have been carefully studied. It is identified by the signature protein coilin and by CB-specific RNAs (scaRNAs). CBs contain high concentrations of splicing small nuclear ribonucleoproteins (snRNPs) and other RNA processing factors, suggesting that they are sites for assembly and/or posttranscriptional modification of the splicing machinery of the nucleus.

Coilin is essential for Cajal body organization in Drosophila melanogaster.

Cajal bodies (CBs) are nuclear organelles that occur in a variety of organisms, including vertebrates, insects, and plants. They are most often identified with antibodies against the marker protein coilin. Because the amino acid sequence of coilin is not strongly conserved evolutionarily, coilin orthologues have been difficult to recognize by homology search.