Stein, Samantha A. et al. (2022) MicroPubl Biol

Maine, Eleanor M., Smith, Harold E., Lissemore, James L., O'Connell, Kevin F., Stein, Samantha A., Zucaro, Olivia F., Spoerke, Jill M.

[MicroPubl Biol, 2022]

Germline stem cell proliferation in C. elegans requires activation of the GLP-1/Notch receptor, which is located on the germline plasma membrane and encoded by the glp-1 gene. We previously identified several genes whose products directly or indirectly promote activity of the GLP-1 signaling pathway by finding mutations that enhance the germline phenotype of a glp-1(ts) allele, glp-1(bn18) . Here, we report phenotypic and molecular analysis of a new ekl-1 allele, ekl-1(om92) , that enhances the glp-1(bn18) phenotype. ekl-1(om92) is a 244 bp deletion predicted to generate a frameshift and premature termination codon, yielding a severely truncated protein, suggesting it is a null allele.

Stein KK et al. (2015) WormBook "The C. elegans eggshell."

Stein KK, Golden A

[WormBook, 2015]

In all animals, oocytes are surrounded by an extracellular matrix upon fertilization. This matrix serves similar purposes in each animal. It functions to mediate sperm binding, to prevent polyspermy, to control the chemical environment of the embryo, and to provide physical protection to the embryo as it developes. The synthesis of the C. elegans matrix, or eggshell, begins when the oocyte enters the spermatheca and is fertilized by a single sperm. The process of eggshell synthesis is thought to take place during the completion of the maternal meiotic divisions such that the multi-layered eggshell is completed by anaphase II. The synthesis of the eggshell occurs in a hierarchical pattern in which the outermost layers are synthesized first in order to capture and retain the innermost layers as they form. Recent studies have revealed that the lipid-rich permeability barrier is distinct from the outer trilaminar eggshell. These new findings alter our previous understanding of the eggshell. This chapter aims to define each of the eggshell layers and the molecules that are known to play significant roles in their formation.

Stein LD (1999) Trends Genet "Internet access to the C. elegans genome."

Stein LD

[Trends Genet, 1999]

In December 1998, the genome of the small soil-dwelling nematode Caenorhabditis elegans became the most recent model to fall to the collective efforts of the Genome Project, its complete 97 Mbp genome taking its place alongside those of Saccharomyces cerevisiae, Escherichia coli and numerous other microorganisms. The availability of the C. elegans sequence means that, for the first time, the complete genome of a fully functional multicellular animal is available to the scientific community, along with a rich infrastructure of genetic, behavioral, physiological and developmental data about the organism.

Stein KC et al. (2022) Nature "Ageing exacerbates ribosome pausing to disrupt cotranslational proteostasis."

Frydman J, Rainbolt TK, van der Lienden J, Morales-Polanco F, Stein KC

[Nature, 2022]

Ageing is accompanied by a decline in cellular proteostasis, which underlies many age-related protein misfolding diseases^1,2. Yet, how ageing impairs proteostasis remains unclear. As nascent polypeptides represent a substantial burden on the proteostasis network³, we hypothesized that altered translational efficiency during ageing could help to drive the collapse of proteostasis. Here we show that ageing alters the kinetics of translation elongation in both Caenorhabditis elegans and Saccharomyces cerevisiae. Ribosome pausing was exacerbated at specific positions in aged yeast and worms, including polybasic stretches, leading to increased ribosome collisions known to trigger ribosome-associated quality control (RQC)^4-6. Notably, aged yeast cells exhibited impaired clearance and increased aggregation of RQC substrates, indicating that ageing overwhelms this pathway. Indeed, long-lived yeast mutants reduced age-dependent ribosome pausing, and extended lifespan correlated with greater flux through the RQC pathway. Further linking altered translation to proteostasis collapse, we found that nascent polypeptides exhibiting age-dependent ribosome pausing in C. elegans were strongly enriched among age-dependent protein aggregates. Notably, ageing increased the pausing and aggregation of many components of proteostasis, which could initiate a cycle of proteostasis collapse. We propose that increased ribosome pausing, leading to RQC overload and nascent polypeptide aggregation, critically contributes to proteostasis impairment and systemic decline during ageing.

Stein GM et al. (2012) Front Genet "The Intersection of Aging, Longevity Pathways, and Learning and Memory in C. elegans."

Stein GM, Murphy CT

[Front Genet, 2012]

Our understanding of the molecular and genetic regulation of aging and longevity has been greatly augmented through studies using the small model system, C. elegans. It is important to test whether mutations that result in a longer life span also extend the health span of the organism, rather than simply prolonging an aged state. C. elegans can learn and remember both associated and non-associated stimuli, and many of these learning and memory paradigms are subject to regulation by longevity pathways. One of the more distressing results of aging is cognitive decline, and while no gross physical defects in C. elegans sensory neurons have been identified, the organism does lose the ability to perform both simple and complex learned behaviors with age. Here we review what is known about the effects of longevity pathways and the decline of these complex learned behaviors with age, and we highlight outstanding questions in the field.

Stein P et al. (2003) RNA "RNAi: mammalian oocytes do it without RNA-dependent RNA polymerase."

Svoboda P, Anger M, Stein P, Schultz RM

[RNA, 2003]

Studies in mutant organisms deficient in RNA interference (RNAi) and related post-transcriptional gene silencing implicated a role for a single class of RNA-dependent RNA polymerases (RdRp). Nevertheless, sequence homologs to these RdRps have not been found in coelomate organisms such as Drosophila or mammals. This lack of homologous sequences does not exclude that an RdRp functions in RNAi in these organisms because an RdRp could be acquired by horizontal transfer from an RNA virus. In fact, such a sequence is found in mice (Aquarius) and we observe that it is expressed in mouse oocytes and early embryos, which exhibit RNAi. We report here that cordycepin, an inhibitor of RNA synthesis, does not prevent Mos double-strand RNA (dsRNA) to target endogenous Mos mRNA in mouse oocytes and that targeting a chimeric Mos-EGFP mRNA with dsRNA to EGFP does not reduce the endogenous Mos mRNA, but does target the chimeric mRNA. These results indicate that an RdRp is not involved in dsRNA-mediated mRNA degradation in mammalian oocytes, and possibly in mammals in general, and therefore that only homologous sequences to the dsRNA are targeted for degradation.

Stein P et al. (2002) Biochem Biophys Res Commun "Analysis of the role of RecQ helicases in RNAi in mammals."

Stein P, Johnson B, Svoboda P, Blackshear PJ, Stumpo DJ, Lombard DB, Schultz RM

[Biochem Biophys Res Commun, 2002]

The identity of mammalian genes involved in RNA interference (RNAi), the targeted sequence-specific mRNA degradation by double-stranded RNA (dsRNA), is poorly defined. Here we report the analysis of mice with null mutations of Wrn, Blm, and RecQ1 genes that are related to Mut-7 and Qde3, two genes essential for RNAi in Caenorhabditis elegans and quelling in Neurospora, respectively. Our results suggest that Wrn, Blm, and RecQ1 are not involved in sequence-specific mRNA degradation in mammals in response to dsRNA, suggesting potential differences in the mammalian RNAi pathway. (C)2002 Elsevier Science (USA).

Stein LD et al. (2003) PLoS Biol "The genome sequence of Caenorhabditis briggsae: a platform for comparative genomics."

Stajich JE, Hillier LW, Rogers J, Clee C, Mardis ER, Blasiar D, Brent MR, Spieth J, Marra MA, D'Eustachio P, Wei C, Minx P, Schein JE, Stein LD, Mullikin JC, Kamath R, Wilson RK, Fitch DHA, Coghlan A, Fulton RE, Waterston RH, Plumb RW, Coulson A, Sohrmann M, Chinwalla A, Griffiths-Jones S, Kuwabara PE, Clarke L, Fulton LA, Willey D, Bao Z, Chen N, Harris TW, Durbin R, Blumenthal T, Miner TL

[PLoS Biol, 2003]

The soil nematodes Caenorhabditis briggsae and Caenorhabditis elegans diverged from a common ancestor roughly 100 million years ago and yet are almost indistinguishable by eye. They have the same chromosome number and genome sizes, and they occupy the same ecological niche. To explore the basis for this striking conservation of structure and function, we have sequenced the C. briggsae genome to a high-quality draft stage and compared it to the finished C. elegans sequence. We predict approximately 19,500 protein-coding genes in the C. briggsae genome, roughly the same as in C. elegans. Of these, 12,200 have clear C. elegans orthologs, a further 6,500 have one or more clearly detectable C. elegans homologs, and approximately 800 C. briggsae genes have no detectable matches in C. elegans. Almost all of the noncoding RNAs (ncRNAs) known are shared between the two species. The two genomes exhibit extensive colinearity, and the rate of divergence appears to be higher in the chromosomal arms than in the centers. Operons, a distinctive feature of C. elegans, are highly conserved in C. briggsae, with the arrangement of genes being preserved in 96% of cases. The difference in size between the C. briggsae (estimated at approximately 104 Mbp) and C. elegans (100.3 Mbp) genomes is almost entirely due to repetitive sequence, which accounts for 22.4% of the C. briggsae genome in contrast to 16.5% of the C. elegans genome. Few, if any, repeat families are shared, suggesting that most were acquired after the two species diverged or are undergoing rapid evolution. Coclustering the C. elegans and C. briggsae proteins reveals 2,169 protein families of two or more members. Most of these are shared between the two species, but some appear to be expanding or contracting, and there seem to be as many as several hundred novel C. briggsae gene families. The C. briggsae draft sequence will greatly improve the annotation of the C. elegans genome. Based on similarity to C. briggsae, we found strong evidence for 1,300 new C. elegans genes. In addition, comparisons of the two genomes will help to understand the evolutionary forces that mold nematode genomes.

Stein KK et al. (2010) Genetics "Functional redundancy of paralogs of an anaphase promoting complex/cyclosome subunit in Caenorhabditis elegans meiosis."

Golden A, Ross BD, Stein KK, Nesmith JE

[Genetics, 2010]

The anaphase promoting complex/cyclosome (APC/C) mediates the metaphase-to-anaphase transition by instructing the ubiquitination and turnover of key proteins at this stage of the cell cycle. We have recovered a gain-of-function allele in an APC5 subunit of the anaphase promoting complex/cyclosome. This finding led us to investigate further the role of APC5 in Caenorhabditis elegans, which contains two APC5 paralogs. We have shown that these two paralogs, such-1 and gfi-3, are coexpressed in the germline but have nonoverlapping expression patterns in other tissues. Depletion of such-1 or gfi-3 alone does not have a notable effect on the meiotic divisions; however, codepletion of these two factors results in meiotic arrest. In sum, the two C. elegans APC5 paralogs have a redundant function during the meiotic divisions.

Stein LD et al. (1998) Genome Res "Scriptable access to the Caenorhabditis elegans genome sequence and other ACEDB databases."

Stein LD, Thierry-Mieg J

[Genome Res, 1998]

Much of the world's genomic data are available to the community through networked databases that are accessed via Web interfaces. Although this paradigm provides browse-level access and has greatly facilitated linking between databases, it does not provide any convenient mechanism for programmatically fetching and integrating data from diverse databases. We have created a library and an application programming interface (API) named AcePerl that provides simple, direct access to ACEDB databases from the Perl programming language. With this library, programmers and computer-savvy biologists can write software to pose complex queries on local and remote ACEDB databases, retrieve the data, integrate the results, and move data objects from one database to another. In addition, a set of Web scripts running on top of AcePerl provides Web-based browsing of any local or remote ACEDB database. AcePerl and the AceBrowser Web browser run on Unix systems and are available under a license that allows for unrestricted use and redistribution. Both packages can be downloaded from URL. A Microsoft Windows port of AcePerl is in the planning stages.