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Cell Biol Int Rep,
1987]
Multiple synaptonemal complexes (polycomplexes) (PC) are similar in structure to synaptonemal complexes (SC) and are also highly conserved through evolution. They have been described in over 70 organisms throughout all life forms. The appearance of PCs are restricted to meiotic and germ-line derived tissues and are most commonly present after SC formation. However, in a number of animals and plants, both extra- and intranuclear PCs are present during premeiotic and pre-pachytene stages. The structure and biochemical composition of PCs is similar to SCs that the basic unit is tripartite, consisting of two lateral elements and a central region (in which transverse elements are located), and the dimensions of such structures are equivalent. Stacking of SC subunits, while still maintaining equivalent SC dimensions, creates a problem since the lateral elements (LE) would then be twice as thick in the PC as compared to the SC. Recently, it has been shown that the LE of the SC is actually multistranded, thus the LE of each subunit of the PC is half as thick as its counterpart in the SC.
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PLoS Genet,
2023]
The successful delivery of genetic material to gametes requires tightly regulated interactions between the parental chromosomes. Central to this regulation is a conserved chromosomal interface called the synaptonemal complex (SC), which brings the parental chromosomes in close proximity along their length. While many of its components are known, the interfaces that mediate the assembly of the SC remain a mystery. Here, we survey findings from different model systems while focusing on insight gained in the nematode C. elegans. We synthesize our current understanding of the structure, dynamics, and biophysical properties of the SC and propose mechanisms for SC assembly.
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Annu Rev Phytopathol,
2011]
The surface coat (SC) of the plant-parasitic nematode cuticle is an understudied area of current research, even though it likely plays key roles in both nematode-plant and nematode-microbe interactions. Although in several ways Caenorhabditis elegans is a poor model for plant-parasitic nematodes, it is a useful starting point for investigations of the cuticle and its SC, especially in the light of recent work using this species as a model for innate immunity and the generic biology underpinning much host-parasite biology. We review the research focused on the involvement of the SC of plant-parasitic nematodes. Using the insights gained from animal-parasitic nematodes and other sequenced nematodes, we discuss the key roles that the SC may play.
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Cell Biochem Biophys,
2006]
RNA interference (RNAi), through expression of small, double-stranded RNAs or short hairpin RNAs, produces sequence-specific mRNA degradation and decreased gene expression. Since its discovery in 1998 (Fire et al., 1998, Nature 391, 806-811), RNAi has rapidly become one of the most widely used technologies for exploring gene function in eukaryotic cells. Although the topic of RNAi has been the subject of a large number of excellent reviews, the focus of this article is on its application to the study of ion channel physiology in animal cells. In this regard, RNAi has provided definitive identification of ion channel subtypes responsible for both basal and stimulated ion conduction across the plasma membrane of several cell types. The approach has been particularly effective in identifying and establishing the contribution of auxiliary subunits and regulatory proteins to the overall function of ion channel complexes. Moreover, selective knockdown of ion channel expression has been a valuable means of demonstrating roles in the development of specific cell domains and in the normal growth of certain cell types. In this review, a brief description of the general mechanism of RNAi is presented, followed by a discussion of some important considerations for the in vitro application of this technology and in producing transgenic animals as models for human disease. We then describe several examples of where RNAi has been used to investigate the physiological role of ion channels in cells from model organisms (Caenorhabditis elegans and Drosophila melanogaster) and in mammalian cells.
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Bioessays,
2007]
In C. elegans and D. melanogaster, specialized sites have an important role in meiotic recombination. Recent evidence has shown that these sites in C. elegans have a role in synapsis. Here we compare the initiation of synapsis in organisms with specialized sites and those without. We propose that, early in prophase, synapsis requires an initiator to overcome inhibitory factors that function to prevent synaptonemal complex (SC) formation between nonhomologous sequences. These initiators of SC formation can be stimulated by crossover sites, possibly other types of recombination sites and also specialized sites where recombination does not occur. BioEssays 29: 217-226, 2007. (c) 2007 Wiley Periodicals, Inc.
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Chromosoma,
2006]
Sexually reproducing organisms rely on meiosis for the formation of haploid gametes. This is achieved through two consecutive rounds of cell division (meiosis I and II) after one round of DNA replication. During the meiotic divisions, chromosomes face several challenges to ultimately ensure proper chromosome segregation. Unique events unfold during meiosis I to overcome these challenges. Homologous chromosomes pair, synapse, and recombine. A remarkable feature throughout this process is the formation of an evolutionarily conserved tripartite proteinaceous structure known as the synaptonemal complex (SC). It is comprised of two lateral elements, assembled along each axis of a pair of homologous chromosomes, and a central region consisting of transverse filaments bridging the gap between lateral elements. While the presence of the SC during meiosis has been appreciated now for 50 years (Moses, Biophys Biochem Cytol 2:215-218, 1956; Fawcett, J Biophys Biochem Cytol 2:403-406, 1956), its role(s) remain a matter of intense investigation. This review concentrates on studies performed in Caenorhabditis elegans, a powerful system for investigating meiosis. Studies in this organism are contributing to the unraveling of the various processes leading to the formation of the SC and the various facets of the functions it exerts throughout meiosis.