Diurnal cycling of rhizosphere bacterial communities is associated with shifts in carbon metabolism

Abstract Background The circadian clock regulates plant metabolic functions and is an important component in plant health and productivity. Rhizosphere bacteria play critical roles in plant growth, health, and development and are shaped primarily by soil communities. Using Illumina next-generation sequencing and high-resolution mass spectrometry, we characterized bacterial communities of wild-type (Col-0) Arabidopsis thaliana and an acyclic line (OX34) ectopically expressing the circadian clock-associated cca1 transcription factor, relative to a soil control, to determine how cycling dynamics affected the microbial community. Microbial communities associated with Brachypodium distachyon (BD21) were also evaluated. Results Significantly different bacterial community structures (P = 0.031) were observed in the rhizosphere of wild-type plants between light and dark cycle samples. Furthermore, 13% of the community showed cycling, with abundances of several families, including Burkholderiaceae, Rhodospirillaceae, Planctomycetaceae, and Gaiellaceae, exhibiting fluctuation in abundances relative to the light cycle. However, limited-to-no cycling was observed in the acyclic CCAox34 line or in soil controls. Significant cycling was also observed, to a lesser extent, in Brachypodium. Functional gene inference revealed that genes involved in carbohydrate metabolism were likely more abundant in near-dawn, dark samples. Additionally, the composition of organic matter in the rhizosphere showed a significant variation between dark and light cycles. Conclusions The results of this study suggest that the rhizosphere bacterial community is regulated, to some extent, by the circadian clock and is likely influenced by, and exerts influences, on plant metabolism and productivity. The timing of bacterial cycling in relation to that of Arabidopsis further suggests that diurnal dynamics influence plant-microbe carbon metabolism and exchange. Equally important, our results suggest that previous studies done without relevance to time of day may need to be reevaluated with regard to the impact of diurnal cycles on the rhizosphere microbial community

Domestic Violence Against Women of Japanese Descent in Los Angeles

Using a more inclusive, culturally responsive measure, this population-based study of women of Japanese descent contrasts two methods of estimating prevalence of domestic violence. Eighty percent of respondents reported experiencing a male partner's violence during their lifetimes—a conventional estimation. A new method took into account the respondent's perceptions about the partner's acts—whether she considered her partner's behavior abusive and placed it within the context of an abusive relationship—and yielded the lifetime prevalence of 61%. Attention to culturally based manifestations of domestic violence and the respondent's perceptions provide additional dimensions of data grounded in women's subjective experiences.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68598/2/10.1177_10778019922181536.pd