Solution structure of the RNA-binding cold-shock domain of the Chlamydomonas reinhardtii NAB1 protein and insights into RNA recognition.

Light-harvesting complex (LHC) proteins are among the most abundant proteins on Earth and play critical roles in photosynthesis, both in light capture and in photoprotective mechanisms. The Chlamydomonas reinhardtii nucleic acid-binding protein 1 (NAB1) is a negative regulator of LHC protein translation. Its N-terminal cold-shock domain (CSD) binds to a 13-nt element [CSD consensus sequence (CSDCS)] found in the mRNA of specific LHC proteins associated with Photosystem II (PSII), an interaction which regulates LHC expression and, consequently, PSII-associated antenna size, structure and function. In the present study, we elucidated the solution structure of the NAB1 CSD as determined by heteronuclear NMR. The CSD adopts a characteristic five-stranded anti parallel ß-barrel fold. Upon addition of CSDCS RNA, a large number of NMR chemical shift perturbations were observed, corresponding primarily to surface-exposed residues within the highly conserved ß2- and ß3-strands in the canonical RNA-binding region, but also to residues on ß-strand 5 extending the positive surface patch and the overall RNA-binding site. Additional chemical shift perturbations that accompanied RNA binding involved buried residues, suggesting that transcript recognition is accompanied by conformational change. Our results indicate that NAB1 associates with RNA transcripts through a mechanism involving its CSD that is conserved with mechanisms of sequence-specific nucleic acid recognition employed by ancestrally related bacterial cold-shock proteins (CSPs).

Sulphur responsiveness of the Chlamydomonas reinhardtii LHCBM9 promoter.

MAIN CONCLUSION: A 44-base-pair region in the Chlamydomonas reinhardtii LHCBM9 promoter is essential for sulphur responsiveness. The photosynthetic light-harvesting complex (LHC) proteins play essential roles both in light capture, the first step of photosynthesis, and in photoprotective mechanisms. In contrast to the other LHC proteins and the majority of photosynthesis proteins, the Chlamydomonas reinhardtii photosystem II-associated LHC protein, LHCBM9, was recently reported to be up-regulated under sulphur deprivation conditions, which also induce hydrogen production. Here, we examined the sulphur responsiveness of the LHCBM9 gene at the transcriptional level, through promoter deletion analysis. The LHCBM9 promoter was found to be responsive to sulphur deprivation, with a 44-base-pair region between nucleotide positions -136 and -180 relative to the translation start site identified as essential for this response. Anaerobiosis was found to enhance promoter activity under sulphur deprivation conditions, however, alone was unable to induce promoter activity. The study of LHCBM9 is of biological and biotechnological importance, as its expression is linked to photobiological hydrogen production, theoretically the most efficient process for biofuel production, while the simplicity of using an S-deprivation trigger enables the development of a novel C. reinhardtii-inducible promoter system based on LHCBM9.

Police Encounters Among Needle Exchange Clients in Baltimore: Drug Law Enforcement as a Structural Determinant of Health.

OBJECTIVES: We piloted a monitoring mechanism to document police encounters around programs targeting people who inject drugs (PWID), and assessed their demographic predictors at 2 Baltimore, Maryland, needle exchange program (NEP) sites. METHODS: In a brief survey, 308 clients quantified, characterized, and sited recent police encounters. Multivariate linear regression determined encounter predictors, and we used geocoordinate maps to illustrate clusters. RESULTS: Within the past 6 months, clients reported a median of 3 stops near NEP sites (interquartile range [IQR] = 0-7.5) and a median of 1 arrest in any location (IQR = 0-2). Three respondents reported police referral to the NEP. Being younger (P = .009), being male (P = .033), and making frequent NEP visits (P = .02) were associated with reported police stops. Among clients reporting arrest or citation for syringe possession, Whites were significantly less likely than non-Whites to report being en route to or from an NEP (P < .001). Reported encounters were clustered around NEPs. CONCLUSIONS: Systematic surveillance of structural determinants of health for PWID proved feasible when integrated into service activities. Improved monitoring is critical to informing interventions to align policing with public health, especially among groups subject to disproportionate levels of drug law enforcement.

Cardiovascular health literacy and treatment adherence in persons with serious mental illness.

Persons with serious mental illnesses have shorter life spans than the general population, and their earlier death is often related to cardiovascular disease. This study examined health literacy and cardiovascular medication adherence in a sample of 98 participants with serious mental illness. Sixty-two percent of the participants had adequate health literacy as measured by the Test of Functional Health Literacy in Adults. The association between health literacy and medication adherence was not significant after controlling for education. There was a significant association between health literacy and education level, health literacy and site, and health literacy and the sodium intake subscale of the Hill-Bone adherence scale.

A social disorganization perspective on bullying-related attitudes and behaviors: the influence of school context.

Social disorganization theory suggests that certain school-level indicators of disorder may be important predictors of bullying-related attitudes and behaviors. Multilevel analyses were conducted on bullying-related attitudes and experiences among 22,178 students in 95 elementary and middle schools. The intraclass correlation coefficients indicated that 0.6-2% of the variance in victimization, 5-10% of the variance in retaliatory attitudes, 5-6% of the variance in perceptions of safety, and 0.9% of the variance in perpetration of bullying was associated with the clustering of students within schools. Although the specific associations varied somewhat for elementary schools as compared to middle schools, the hierarchical linear modeling analyses generally suggested that school-level indicators of disorder (e.g., student-teacher ratio, concentration of student poverty, suspension rate, and student mobility) were significant predictors of bullying-related attitudes and experiences. Student-level characteristics (i.e., sex, ethnicity, status in school) were also relevant to students' retaliatory attitudes, perceptions of safety, and involvement in bullying. Implications for school-based research and violence prevention are provided.

Examining ethnic, gender, and developmental differences in the way children report being a victim of "bullying" on self-report measures.

PURPOSE: Racial/ethnic differences in children's self-reports of being a frequent victim of bullying were assessed via two commonly used strategies: a definition-based single-item measure and behavior-based multiresponse measure. METHODS: Logistic regression analyses were conducted on survey data from 24,345 youth to examine ethnic differences in youths' responses to definition-based and behavior-based measures of victimization. Separate analyses were conducted for boys and girls at different school levels. RESULTS: Prevalence estimates were higher using the behavior-based measure than definition-based measure. Several ethnic differences emerged, such that African American youth tended to be less likely than their white counterparts to indicate that they were bullied using the definition-based measure. African American girls and African American and Asian middle-school boys who reported being a victim via the behavior-based measure were less likely to report being a frequent victim of "bullying" via the definition-based measure. CONCLUSION: Prevalence estimates vary considerably by the way in which victimization is assessed. African American youth who were victimized tended to under-report being a victim of "bullying." Self-report studies of bullying should carefully consider the measures used to assess victimization.