In most sexually reproducing organisms, the fundamental process of meiosis is implemented concurrently with two differentiation programs that occur at different rates and generate distinct cell types, sperm and oocytes. However, little is known about how the meiotic program is influenced by such contrasting developmental programs. Here we present a detailed timeline of late meiotic prophase during spermatogenesis in Caenorhabditis elegans using cytological and molecular landmarks to interrelate changes in chromosome dynamics with germ cell cellularization, spindle formation, and cell cycle transitions. This analysis expands our understanding C. elegans spermatogenesis, as it identifies multiple spermatogenesis-specific features of the meiotic program and provides a framework for comparative studies. Post-pachytene chromatin of spermatocytes is distinct from that of oocytes in both composition and morphology. Strikingly, C. elegans spermatogenesis includes a previously undescribed karyosome stage, a common but poorly understood feature of meiosis in many organisms. We find that karyosome formation, in which chromosomes form a constricted mass within an intact nuclear envelope, follows desynapsis, involves a global down-regulation of transcription, and may support the sequential activation of multiple kinases that prepare spermatocytes for meiotic divisions. In spermatocytes, the presence of centrioles alters both the relative timing of meiotic spindle assembly and its ultimate structure. These microtubule differences are accompanied by differences in kinetochores, which connect microtubules to chromosomes. The sperm-specific features of meiosis revealed here illuminate how the underlying molecular machinery required for meiosis is differentially regulated in each sex.

In Taiwan, a screening system using an infant stool color card to promote the early diagnosis of biliary atresia (BA) was established in 2002. This study aimed to investigate the 5-year outcome of BA before and after using the screening program. BA patients were divided into three cohorts according to their birth dates. The patients in cohort A (n 5 89) were born before the stool card screening program (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000); those in cohort B (n 5 28) were screened by the stool card regional screening program (2002)(2003); and those in cohort C (n 5 74) were screened by the stool card universal screening program (2004)(2005). The relative odds ratios were computed using logistic regression to compare the different factors affecting survival time. The rate of age at Kasai operation <60 days was 49.4% and 65.7% in cohorts A and B1C, respectively (P 5 0.02). The jaundice-free (total serum bilirubin <2.0 mg/dL) rate 3 months after surgery was 34.8% and 60.8% in cohorts A and B1C, respectively (P < 0.001). The 3-year jaundice-free survival rate with native liver was 31.5% in cohort A and 56.9% in cohort B1C (P < 0.001), whereas the 3-year overall survival rates were 64.0% and 89.2%, respectively (P < 0.001). The 5-year jaundice-free survival rate with native liver was 27.3% in cohort A and 64.3% in cohort B (P < 0.001), and the 5-year overall survival rates were 55.7% and 89.3%, respectively (P < 0.001). Conclusion: The stool color card screening program for BA allows for earlier Kasai operation, which increases the jaundice-free rate at 3 months postsurgery. With higher surgical success rates, the 3-and 5-year outcome of BA patients in Taiwan improves remarkably. (HEPATOLOGY 2011;53:202-208)

GPR-1/2 (regulators of Gα signaling necessary for asymmetric cell division) receives a positional cue from Let-99, resulting in its appropriate distribution around the posterior cortex.

The conserved PAR proteins are localized in asymmetric cortical domains and are required for the polarized localization of cell fate determinants in many organisms. In Caenorhabditis elegans embryos, LET-99 and G protein signaling act downstream of the PARs to regulate spindle positioning and ensure asymmetric division. PAR-3 and PAR-2 localize LET-99 to a posterior cortical band through an unknown mechanism. Here we report that LET-99 asymmetry depends on cortically localized PAR-1 and PAR-4 but not on cytoplasmic polarity effectors. In par-1 and par-4 embryos, LET-99 accumulates at the entire posterior cortex, but remains at low levels at the anterior cortex occupied by PAR-3. Further, PAR-3 and PAR-1 have graded cortical distributions with the highest levels at the anterior and posterior poles, respectively, and the lowest levels of these proteins correlate with high LET-99 accumulation. These results suggest that PAR-3 and PAR-1 inhibit the localization of LET-99 to generate a band pattern. In addition, PAR-1 kinase activity is required for the inhibition of LET-99 localization, and PAR-1 associates with LET-99. Finally, examination of par-1 embryos suggests that the banded pattern of LET-99 is critical for normal posterior spindle displacement and to prevent spindle misorientation caused by cell shape constraints.

Sperm from different species have evolved distinctive motility structures, including tubulin-based flagella in mammals and major sperm protein (MSP)-based pseudopods in nematodes. Despite such divergence, we show that sperm-specific PP1 phosphatases, which are required for male fertility in mouse, function in multiple processes in the development and motility of Caenorhabditis elegans amoeboid sperm. We used live-imaging analysis to show the PP1 phosphatases GSP-3 and GSP-4 (GSP-3/4) are required to partition chromosomes during sperm meiosis. Postmeiosis, tracking fluorescently labeled sperm revealed that both male and hermaphrodite sperm lacking GSP-3/4 are immotile. Genetic and in vitro activation assays show lack of GSP-3/4 causes defects in pseudopod development and the rate of pseudopodial treadmilling. Further, GSP-3/4 are required for the localization dynamics of MSP. GSP-3/ 4 shift localization in concert with MSP from fibrous bodies that sequester MSP at the base of the pseudopod, where directed MSP disassembly facilitates pseudopod contraction. Consistent with a role for GSP-3/4 as a spatial regulator of MSP disassembly, MSP is mislocalized in sperm lacking GSP-3/4. Although a requirement for PP1 phosphatases in nematode and mammalian sperm suggests evolutionary conservation, we show PP1s have independently evolved sperm-specific paralogs in separate lineages. Thus PP1 phosphatases are highly adaptable and employed across a broad range of sexually reproducing species to regulate male fertility.