No abstract

Spo11 is a homolog of a subunit of archaebacterial topoisomerase, which catalyzes DNA double-strand breaks and initiates homologous chromosome recombination. In the present study, we silenced the SPO11-1 gene in rice (Oryza sativa) using RNAi. Rice plants with loss-of-function of OsSPO11-1 have no apparent growth defects during vegetative development, but homologous chromosome pairing and recombination are significantly obstructed. Telomeres can be assembled as bouquet during the zygotene stage of the OsSPO11-1-deficient plants, just as that in wild type. Although the two axial-associated proteins, REC8 and PAIR2, are loaded onto the chromosomes, the depletion of PAIR2 from the chromosomes is much later than in wild type. The central element of the synaptonemal complex (SC), ZEP1, does not load onto the chromosomes normally, implying that SC formation is disturbed severely. The crossover protein, MER3, isn't efficiently assembled onto chromosomes and the lack of bivalent suggests that crossovers are also affected in the absence of OsSPO11-1. Thus, OsSPO11-1 is essential for both homologous chromosomes pairing and crossover formation during meiosis in rice.

No abstract

The HPSAS is an objective instrument used to evaluate the process and outcomes of the HPS program. In the future, combinations of different types of data (e.g. students' health behaviors, school climate, or teachers' health-teaching innovations) will enable further validation of the HPS effectiveness.

The aim was to comprehensively examine school-based tobacco policy status, implementation and students' perceived smoking at school in regard to gender-specific differences in smoking behavior. We conducted a multilevel-based study to assess two-level effects for smoking among 2350 grades three to six students in 26 randomly selected elementary schools in southern Taiwan. A series of multilevel models were analyzed separately for male and female students. The school-level variables appear to be related to smoking behavior in male students. Among males, the risk of ever-smoking was significantly associated with those schools without antitobacco health education activities or curricula [adjusted odds ratio (aOR) = 6.23, 95% confidence interval (CI): 2.55-15.24], with a high perceived smoking rate (aOR = 3.08, 95% CI: 1.41-6.72) and located in a mountainous region (aOR = 2.53, 95% CI: 1.15-5.58). The risk of ever-smoking among females was significantly associated with those schools without antitobacco activities or curricula (aOR = 3.10, 95% CI: 1.27-7.55). As compared with female counterparts, the specific school that the male students attended had a positive significant effect on the risk of being ever-smokers. The findings suggest that effective tobacco policy implementation should be considered in elementary schools that are currently putting children at the greatest risk for cigarette smoking, especially in regard to male students.