The bHLH Transcription Factor OsbHLH057 Regulates Iron Homeostasis in Rice.

Many basic Helix-Loop-Helix (bHLH) transcription factors precisely regulate the expression of Fe uptake and translocation genes to control iron (Fe) homeostasis, as both Fe deficiency and toxicity impair plant growth and development. In rice, three clade IVc bHLH transcription factors have been characterised as positively regulating Fe-deficiency response genes. However, the function of OsbHLH057, another clade IVc bHLH transcription factor, in regulating Fe homeostasis is unknown. Here, we report that OsbHLH057 is involved in regulating Fe homeostasis in rice. OsbHLH057 was highly expressed in the leaf blades and lowly expressed in the roots; it was mainly expressed in the stele and highly expressed in the lateral roots. In addition, OsbHLH057 was slightly induced by Fe deficiency in the shoots on the first day but was not affected by Fe availability in the roots. OsbHLH057 localised in the nucleus exhibited transcriptional activation activity. Under Fe-sufficient conditions, OsbHLH057 knockout or overexpression lines increased or decreased the shoot Fe concentration and the expression of several Fe homeostasis-related genes, respectively. Under Fe-deficient conditions, plants with an OsbHLH057 mutation showed susceptibility to Fe deficiency and accumulated lower Fe concentrations in the shoot compared with the wild type. Unexpectedly, the OsbHLH057-overexpressing lines had reduced tolerance to Fe deficiency. These results indicate that OsbHLH057 plays a positive role in regulating Fe homeostasis, at least under Fe-sufficient conditions.

Meat proteins in a high-fat diet have a substantial impact on intestinal barriers through mucus layer and tight junction protein suppression in C57BL/6J mice.

Protein diets are well known for body maintenance and weight loss. However, it remains unclear whether and how different protein sources affect the intestinal epithelial integrity through tight junctions, mucus secretions and host immunity in diet-induced obesity. To evaluate possible effects, soybean, chicken and pork proteins either with low fat (12% kcal) or high fat (60% kcal) were administered to C57BL/6J mice for 12 weeks. Muc2 expression, tight junction proteins, goblet cells, and inflammatory cytokines in the colon and serum were measured. The intake of a high-fat pork protein diet decreased the number of goblet cells and inhibited Muc2 expression in the colon, which impaired the mucus barrier. Immunohistochemistry indicated decreased crypt depth and downregulation of tight junction proteins in high-fat diet fed mice, signifying losses of epithelial barriers. In addition, a pork protein diet reduces the key zonula occludens-1 and E-cadherin proteins. A high-fat meat protein diet induces colonic inflammatory injury by upregulating several key cytokines and increasing IL-1ß, TNF-α, IL-6 and IFN-γ concentrations in serum. The intake of high-fat meat protein diets resulted in the impairment of the colon barrier through mucus suppression, downregulation of tight junctions, and gut inflammation in mice.

OsYSL13 Is Involved in Iron Distribution in Rice.

The uptake and transport of iron (Fe) in plants are both important for plant growth and human health. However, little is known about the mechanism of Fe transport in plants, especially for crops. In the present study, the function of yellow stripe-like 13 (YSL13) in rice was analyzed. OsYSL13 was highly expressed in leaves, especially in leaf blades, whereas its expression was induced by Fe deficiency both in roots and shoots. Furthermore, the expression level of OsYSL13 was higher in older leaves than that in younger leaves. OsYSL13 was located in the plasma membrane. Metal measurement revealed that Fe concentrations were lower in the youngest leaf and higher in the older leaves of the osysl13 mutant under both Fe sufficiency and deficiency conditions, compared with the wild type and two complementation lines. Moreover, the Fe concentrations in the brown rice and seeds of the osysl13 mutant were also reduced. Opposite results were found in OsYSL13 overexpression lines. These results suggest that OsYSL13 is involved in Fe distribution in rice.