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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.08.047 Byline: Ken Chih-Chien Cheng (1), Richard Klancer (2), Andrew Singson (2), Geraldine Seydoux (1) Keywords: DEVBIO; SIGNALING Abstract: DYRKs are kinases that self-activate in vitro by autophosphorylation of a YTY motif in the kinase domain, but their regulation in vivo is not well understood. In C. elegans zygotes, MBK-2/DYRK phosphorylates oocyte proteins at the end of the meiotic divisions to promote the oocyte-to-embryo transition. Here we demonstrate that MBK-2 is under both positive and negative regulation during the transition. MBK-2 is activated during oocyte maturation by CDK-1-dependent phosphorylation of serine 68, a residue outside of the kinase domain required for full activity in vivo. The pseudotyrosine phosphatases EGG-4 and EGG-5 sequester activated MBK-2 until the meiotic divisions by binding to the YTY motif and inhibiting MBK-2's kinase activity directly, using a mixed-inhibition mechanism that does not involve tyrosine dephosphorylation. Our findings link cell-cycle progression to MBK-2/DYRK activation and the oocyte-to-embryo transition. Author Affiliation: (1) Department of Molecular Biology and Genetics and Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 N. Wolfe Street, PCTB 706, Baltimore, MD 21205, USA (2) Waksman Institute and Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA Article History: Received 10 December 2008; Revised 4 June 2009; Accepted 26 August 2009 Article Note: (miscellaneous) Published: October 29, 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.04.036 Byline: Brian Geldziler, Indrani Chatterjee, Andrew Singson Keywords: Fertilization; Sperm; Spermiogenesis; Spermatogenesis; C. elegans Abstract: During the process of spermiogenesis (sperm activation) in Caenorhabditis elegans, the dramatic morphological events that ultimately transform round sessile spermatids into polar motile spermatozoa occur without the synthesis of any new gene products. Previous studies have identified four genes (spe-8, spe-12, spe-27 and spe-29) that specifically block spermiogenesis and lead to hermaphrodite-specific fertility defects. Here, we report the cloning and characterization of a new component of the sperm activation pathway, spe-19, that is required for fertility in hermaphrodites. spe-19 is predicted to encode a novel single-pass transmembrane protein. The spe-19 mutant phenotype, genetic interactions and the molecular nature of the gene product suggest SPE-19 to be a candidate for the receptor/co-receptor necessary for the transduction of the activation signal across the sperm plasma membrane. Author Affiliation: Waksman Institute, Department of Genetics, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854, USA Article History: Received 28 October 2004; Revised 28 April 2005; Accepted 28 April 2005

The spe-9 gene is required for fertility in Caenorhabditis elegans and encodes a sperm transmembrane protein with an extracellular domain (ECD) that contains 10 epidermal growth factor (EGF) repeats. Deletion analysis reveals that the EGF repeats and the transmembrane domain are required for fertilization. In contrast, the cytoplasmic region of SPE-9 is not essential for fertilization. Individual point mutations in all 10 EGF motifs uncover a differential sensitivity of these sequences to alteration. Some EGF repeats cannot tolerate mutation leading to a complete lack of fertility. Other EGF repeats can be mutated to create animals with temperature-sensitive (ts) fertility phenotypes. All ts mutations were generated by changing either conserved cysteine of glycine residues in the EGF motifs. For two endogenous ts alleles of spe-9, loss of function at nonpermissive temperatures is not due to protein mislocalization of degradation. Additionally, the proper localization of SPE-9 in sperm is not altered in a genetically interacting fertility mutant (spe-13) or a mutant that affects sperm vesicle-plasma membrane fusion (fer-1). Like the EGF repeats in the Notch/LIN-12/GLP-1 receptors and their ligands, the EGF repeats in SPE-9 may carry out different functions. Because EGF motifs are found in many proteins in different species, similar experimental strategies could be used to generate useful temperature-sensitive mutations in other EGF motif-containing molecules. Keywords: Fertilization; Germ line expression; EGF repeat

A study was done to describe the phenotypic and molecular characterization of the mutant spe-9 gene in the nematode worm C. elegans. This gene encodes a sperm transmembrane protein with an extracellular domain that contains EGF-like repeats which involved in extracellular functions such as adhesive and ligand-receptor interactions. The overall structure of the predicted mutant phenotype SPE-9 protein is similar to that of ligands for the Notch/LIN-12/GLP-1 transmembrane receptors. Results suggest that SPE-9 functions in specialized cell-cell interactions required for fertilization.

The nematode Caenorhabditis elegans is an attractive model system for the study of fertilization. C. elegans exists as a self-fertilizing hermaphrodite or as a male. This unusual situation provides an excellent opportunity to identify and maintain sterile mutants that affect sperm and no other cells. Analysis of these mutants can identify genes that encode proteins required for gamete recognition, adhesion, signaling, fusion, and/or activation at fertilization. These genes can also provide a starting point for the identification of additional molecules required for fertility. This review describes progress in the genetic and molecular dissection of fertilization in C. elegans and related studies on sperm competition. Key Words: C. elegans; fertilization; sperm; oocyte; sperm competition.

Abstract: Calcium plays a prominent role during fertilization in many animals. This review focuses on roles of Ca2+ during the events around fertilization in the model organism, Caenorhabditis elegans. Specifically, the role of Ca2+ in sperm, oocytes and the surrounding somatic tissues during fertilization will be discussed, with the focus on sperm activation, meiotic maturation of oocytes, ovulation, sperm–egg interaction and fertilization. [Copyright &y& Elsevier]

Abstract: Although much is known about female reproductive aging, fairly little is known about the causes of male reproductive senescence. We developed a method that facilitates culture maintenance of Caenorhabditis elegans adult males, which enabled us to measure male fertility as populations age, without profound loss of males from the growth plate. We find that the ability of males to sire progeny declines rapidly in the first half of adult lifespan and we examined potential factors that contribute towards reproductive success, including physical vigor, sperm quality, mating apparatus morphology, and mating ability. Of these, we find little evidence of general physical decline in males or changes in sperm number, morphology, or capacity for activation, at time points when reproductive senescence is markedly evident. Rather, it is the loss of efficient mating ability that correlates most strongly with reproductive senescence. Low insulin signaling can extend male ability to sire progeny later in life, although insulin impact on individual facets of mating behavior is complex. Overall, we suggest that combined modest deficits, predominantly affecting the complex mating behavior rather than sperm quality, sum up to block effective C. elegans male reproduction in middle adult life. [Copyright &y& Elsevier]