N4-methylcytidine ribosomal RNA methylation in chloroplasts is crucial for chloroplast function, development, and abscisic acid response in Arabidopsis.

Although the essential role of messenger RNA methylation in the nucleus is increasingly understood, the nature of ribosomal RNA (rRNA) methyltransferases and the role of rRNA methylation in chloroplasts remain largely unknown. A recent study revealed that CMAL (for Chloroplast mr aW- Like) is a chloroplast-localized rRNA methyltransferase that is responsible for N4-methylcytidine (m4 C) in 16S chloroplast rRNA in Arabidopsis thaliana. In this study, we further examined the role of CMAL in chloroplast biogenesis and function, development, and hormone response. The cmal mutant showed reduced chlorophyll biosynthesis, photosynthetic activity, and growth-defect phenotypes, including severely stunted stems, fewer siliques, and lower seed yield. The cmal mutant was hypersensitive to chloroplast translation inhibitors, such as lincomycin and erythromycin, indicating that the m4 C-methylation defect in the 16S rRNA leads to a reduced translational activity in chloroplasts. Importantly, the stunted stem of the cmal mutant was partially rescued by exogenous gibberellic acid or auxin. The cmal mutant grew poorer than wild type, whereas the CMAL-overexpressing transgenic Arabidopsis plants grew better than wild type in the presence of abscisic acid. Altogether, these results indicate that CMAL is an indispensable rRNA methyltransferase in chloroplasts and is crucial for chloroplast biogenesis and function, photosynthesis, and hormone response during plant growth and development.

The Influence of Household Refrigerator Ownership on Diets in Vietnam.

Refrigerator ownership accompanies socio-economic development, with the potential to change human diets. Household refrigerator ownership in Vietnam has increased from 13% to 59% between 2004-2014. This study estimates changes in food consumption and diet linkages with household refrigerator ownership in Vietnam, while controlling for socioeconomic variables. We use a two-step instrumental variable regression model on two panels of the Vietnam Household Living Standards Survey covering 2004-2014. Our study finds refrigerator ownership to be significantly associated with decreases in per-capita calorie intake over both periods. Refrigerator ownership may be connected with households substituting lower-nutrient foods with higher ones, with substantial decreases in starchy staple food consumption connected with refrigerator ownership in both panels. For both periods, refrigerator ownership is significantly connected with increased dairy consumption, potentially reflecting the refrigerator increasing a household's ability to store dairy products.