Spermiation, the release of late spermatids from the Sertoli cell, is disrupted by a number of toxicants. Control of the spermiation process, and the proteins that interact to adhere mature spermatids to Sertoli cells, is poorly understood. In these studies we used immunohistochemistry, coimmunoprecipitation/Western blotting, and mass spectrometry to refine an earlier model of sperm adhesion proposed by our laboratory. We have identified specific proteins linked together as part of a multiprotein complex, as well as several additional proteins (cortactin, ERK1/2, and 14-3-3 zeta) that may be functioning in both structural and signal transduction roles. The current and prior data suggest that protein phosphorylation is central to the control of spermiation. We also present and characterize an in vitro tubule culture system that allowed functional testing of the spermiation model by pharmacologic manipulation, and yielded data consistent with the importance of protein phosphorylation in spermiation.

Significance RNA regulation occurs at many levels including processing to mature forms, subcellular localization, and translation. RNA-binding proteins are crucial to direct and regulate these processes. Pumilio/feminization of XX and XO animals (fem)-3 mRNA-binding factor (PUF) proteins are RNA-binding proteins formed from eight α-helical repeats [Pumilio (PUM) repeats] that recognize specific mRNA sequences. Previous structural studies revealed characteristic curved structures and sequence specificity unique to these classical PUF proteins. We show here that PUM repeats also form different folds with 11 PUM repeats. Moreover, these proteins, exemplified by human Puf-A and yeast Puf6 proteins, recognize double-stranded RNA or DNA without sequence specificity. Interestingly, Puf-A and Puf6 PUM repeats lack specificity for RNA bases yet use residues at conserved positions on topologically equivalent protein surfaces for new nucleic acid recognition modes.

The authors wish to make a correction to the above article that was published in J. Neurochem. 88, pp. 1168-1178.The concentrations of 'Plasma non-esterified fatty acid' and 'Brain acyl-CoA' were incorrect. The corrected table has been reproduced below.

The esters of o-phthalic acid are employed extensively in the manufacture of plastics where they are used to impart flexibility. Since they are not covalently linked to the plastic polymer, they can leach from the matrix, providing opportunity for widespread exposure [see Thomas and Thomas (1) for review]. The phthalate ester di-nbutylphthalate (DBP) is used in the manufacture of consumer products as diverse as nail polish, insect repellents, and denture base material (2-4). DBP has recently been found to have clinical applications as well, selectively eliminating tumor cells from bone marrow (5,6).DBP has been previously characterized as a developmental and reproductive toxicant in the rat (7)(8)(9)(10)(11)(12). Comparable oral doses of DBP given to juvenile and adult male rats produces a testicular lesion characterized by early sloughing of germ cells, vacuolization of the Sertoli cell cytoplasm, and testicular atrophy (7,10). It has also been shown that the testicular toxicity of phthalates is age dependent, with immature animals being more sensitive than mature animals (13,14). However, the reproductive toxicity following exposure during development has not been addressed. Although no data are available specifically on the transfer of DBP across the placenta, studies with other phthalate esters show that these compounds readily cross the placenta of rats (15)(16)(17) (195) under the RACB protocol. This is expected in the RACB design because the Fo rats are exposed only as adults, the F1 rats are born to mothers that are treated during gestation and lactation, and the F1 animals themselves are treated during maturation to sexual maturity and through mating. The results of this DBP RACB study are presented below; the results show that structural defects are seen in the second generation rats that were not found in the first. MethodsGeneral. This study was conducted using the National Toxicology Program's RACB protocol for which the detailed methods have been previously described (20,21). Briefly, the protocol is composed of four segments, or tasks. Task 1 is a 14-day range-finding study that is used to set three dose levels used in Task 2. Task 2 is the 14-week continuous breeding phase, generating up to five litters per pair. Task 3 consists of crossover matings between treated and control Fo animals to determine the affected sex, and Task 4 assesses the fertility of the last litter (F1) born during continuous breeding (Task 2).Chemical. DBP was obtained from Chem Central via Midwest Research Institute (Kansas City, MO, Lot/Batch # L-121 1-83/02). The purity of DBP used in preparation of the feed formulations was greater than 99% as determined by gas chromatography. Dosed feed formulations. DBP was blended into powdered NIH-07 (Zeigler Bros., Gardeners, PA) feed on a weight-to-