R. Dwayne Lunsford

Genomic mapping of murine Zp-2 and Zp-3, two oocyte-specific loci encoding zona pellucida proteins.

The zona pellucida is a unique, oocyte-specific matrix that coats the surface of all mammalian eggs. Composed of three sulfated glycoproteins in the mouse (ZP1, ZP2, and ZP3), the zona pellucida facilitates early events in fertilization and protects the embryo during preimplantation development. Using DNA isolated from hamster-mouse somatic cell hybrids and from C57BL/6J X Mus spretus interspecific backcross progeny, Zp-2 was located on chromosome 7, 11.3 +/- 3.2 cM distal to Tyr, and Zp-3 was located on chromosome 5, 9.2 +/- 2.9 cM distal to Gus.

Determination of the Transcript Size and Start Site of the Putative sca Operon of Streptococcus gordonii ATCC 51656 (Formerly Strain PK488)

Streptococci are the primary early colonizers in the accretion of dental plaque. Studies have shown that they can adhere to the acquired pellicle of the tooth, to other oral genera, and to other species of oral streptococci9. The surface protein ScaA from Streptococcus gordonii ATCC 51656 has been characterized and is thought to mediate coaggregation of this organism with another early colonizer Actinomyces naeslundii ATCC 51655 (formerly strain PK606)4. ScaA appears as a 38-kDa protein in immunoblots of surface preparations of the wild type strain ATCC 51656, but the protein is absent or greatly reduced in strain PK1804, an isogenic mutant of strain ATCC 51656 which fails to coaggregate with strain ATCC 51655. Immunoblots of surface preparations from eleven other streptococcal coaggregation partners of ATCC 51655 showed the presence of the 38-kDa protein when probed with PK1804-absorbed anti-ATCC 51656 serum1.

Developmental expression of the sperm receptor of the mouse zona pellucida.

Fertilization is the culmination of a series of carefully orchestrated events that result in the formation of a one-cell zygote with the potential to develop into an adult animal.’ The molecular details of these events have been intensely investigated over the last decade, and the importance of the role of the zona pellucida at fertilization and during early development has become increasingly clear. The zona mediates the relatively species-specific binding of sperm to ovulated eggs, which results in the induction of the acrosome reaction, crucial to penetration of the zona by the capacitated sperm. Following fertilization, the zona pellucida is modified to prevent the penetration of additional sperm, and thus it acts as a major barrier to polyspermy. The zona also provides protection for the early embryo as it passes down the oviduct before implantation.’-’ Many of these molecular details have been elucidated using the mouse as an experimental system. The mouse zona pellucida can be isolated as an intact structure (FIG. 1) and is composed of three sulfated glycoproteins designated ZP1, ZP2, and ZP3, with average molecular weights of 185-200,000, 120140,000, and 83,000 daltons, respect i~ely.~.~ These proteins are synthesized during oogenesis and secreted to form an extracellular glycocalyx which surrounds the growing oocyte, ovulated egg, and dividing embryo. Specific functions have been ascribed to each protein. ZP3 contains 0-linked oligosaccharide side chains capable of inhibiting in vitro sperm-egg interactions, and the presence of at least a portion of its polypeptide backbone is necessary for the induction of the sperm acrosome reaction. ZP2 appears to act as a secondary sperm receptor, and its postfertilization modification may play a role in the block to polyspermy. ZP1, which is a dimer, may serve to cross-link copolymers of ZP2 and ZP3 and thus add structural integrity to the zona to facilitate the protection of the embryo as it passes down the o v i d u ~ t . ” ~ Although this report will concentrate on the mouse zona pellucida, it must be realized that important strides have been made investigating the zonae of a number of other species, particularly the pig and cow. We recently undertook to clone the genes that code for mouse ZP1, ZP2, and ZP3. Our results indicate that the zona genes constitute a family of single-copy genes that are located on different chromosomes and are developmentally regulated and