The Caenorhabditis elegans spe-6 gene is required for major sperm protein assembly and shows second site non-complementation with an unlinked deficiency.

Caenorhabditis elegans spermatozoa move by crawling. Their motility requires thin cytoskeletal filaments assembled from a unique cytoskeletal protein, the major sperm protein (MSP). During normal sperm development the MSP is segregated to developing sperm by assembly into filaments that form a paracrystalline array in a transient organelle, the fibrous body-membranous organelle. Mutations in the spe-6 gene cause sterility because they lead to defective primary spermatocytes that do not form spermatids. In these mutant spermatocytes the MSP fails to assemble into fibrous body filaments. Instead, the unassembled MSP distributes throughout the cytoplasm and nucleus. Thus, the spe-6 gene product is necessary for normal MSP localization and assembly during sperm development. In addition to their MSP assembly defect, spe-6 mutant spermatocytes arrest meiosis at diakinesis although their spindle pole bodies still replicate and separate. This results in spermatocytes with four half-spindles surrounding condensed, but unsegregated, chromosomes. All four spe-6 alleles, as well as a chromosome III deficiency that deletes the spe-6 gene, fail to complement two small overlapping chromosome IV deficiencies, eDf18 and eDf19. This non-allele-specific second site non-complementation suggests a concentration-dependent interaction between the spe-6 gene product and products of the gene(s) under eDf18 and eDf19, which include a cluster of sperm-specific genes. Since MSP filament assembly is highly concentration-dependent in vitro, the non-complementation might be expected if the sperm-specific gene products under eDf18 and eDf19 were needed together with the spe-6 gene product to promote MSP assembly.

Cuticular Collagenous Proteins of Second-stage Juveniles and Adult Females of Meloidogyne incognita: Isolation and Partial Characterization.

Cuticles isolated from second-stage juveniles and adult females of Meloidogyne incognita were purified by treatment with 1% sodium dodecyl sulfate (SDS). The juvenile cuticle was composed of three zones differing in their solubility in beta-mercaptoethanol (BME). Proteins in the cortical and median zones were partially soluble in BME, whereas the basal zone was the least soluble. The BME-soluble proteins from the juvenile cuticle were separated into 12 bands by SDS-polyacrylamide gel electrophoresis and characterized as collagenous proteins based on their sensitivity to collagenase and amino acid composition. The adult cuticle consisted of two zones which were dissolved extensively by BME. The basal zone was completely solubilized, leaving behind a network of fibers corresponding to the cortical zone. The BME-soluble proteins from the adult cuticle were separated by electrophoresis into nine bands one of which constituted > 55% of the total BME-soluble proteins. All bands were characterized as collagenous proteins. Collagenous proteins from juvenile cuticles also contained glycoproteins which were absent from the adult cuticles.