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Key Message: ZmNAC34 might function as an important regulator of starch synthesis by decreasing total starch accumulation and soluble sugar content and increasing amylose fractions. Starch is a major component in endosperm and directly influences seed yield and the cooking quality of cereal grains. Starch is synthesized through a series of complex biological processes. Nevertheless, the mechanism by which starch biosynthesis is regulated in maize is still unclear. In this study, ZmNAC34, a NAC transcription factor related to starch synthesis, was screened based on transcriptome sequencing data. Subsequent qRT-PCR analysis showed that ZmNAC34 is specifically expressed in maize endosperm. Transactivation and subcellular localization assays revealed that ZmNAC34 possesses two characteristics of transcription factors: nuclear localization and transactivation activity. Overexpression of ZmNAC34 in rice decreased total starch accumulation and soluble sugar content, while increased amylose fractions. Meanwhile, the transgenic seeds exhibited alterant starch structure and abnormal morphology. In addition, compared with WT seeds, most of the 17 starch biosynthesis-related genes were significantly upregulated in transgenic seeds from 6 to 15 DAP (day after pollination). These data reveal that ZmNAC34 might function as an important regulator of starch synthesis, thus providing a new perspective on controlling seed yield and quality.

[Display omitted] • The pH-dependent depression ability of NS on hematite flotation was studied. • NS has a stronger depressing ability for hematite under alkaline conditions. • NS is more easily adsorbed onto hematite surfaces in the alkaline environment. • NS is chemisorbed onto all Fe at the hematite surface with a stronger force in pH 10.0. • It is attributed to the strong acid-base interaction between ionized NS and hydroxylated hematite. Depressant starch (NS) was generally used in hematite flotation, while the adsorption mechanism of the macromolecular polymer onto mineral surfaces remained in question. In this study, novel detection approaches and computational chemistry methods were introduced to update the widely-accepted acid-base interaction theory. Microflotation tests confirm that the hematite flotation recovery was easily depressed by NS under the acid or alkaline conditions rather than the neutral condition. Zeta potential measurement shows that NS could change the zeta potential of hematite, while the shift amplitude ranked as alkaline > acid > neutral, indicating the most suitable pH range is the alkaline condition. XPS analysis reveals that NS could chemisorbed onto Fe atoms of hematite surface via C-O groups in the whole studied pH range. It was further verified using AFM tests, in which the NS has a stronger interaction force under the alkaline environment. MDS further indicates that the interaction energy between NS and the (0 0 1) hematite surface was three times greater than others under alkaline conditions. In general, the interaction force at the interface between the hematite surface and NS was a strong chemical adsorption at the alkaline conditions while there was weak chemisorption and hydrogen bonding under the neutral or acidic conditions. [ABSTRACT FROM AUTHOR]

Native starches and their phosphates with various molecular structures was introduced as the depressant to realize the flotation of quartz from hematite in this study. The present starch phosphates (WSP, NSP, GSP) were modified by the reaction between phosphate and three different corn starches (WS, NS, G50). The synthesis and characterization of starch phosphates found that starch with high amylopectin content was easily modified into starch phosphates. Microflotation tests showed that starch phosphates exhibited stronger depressing abilities of hematite flotation than native starches. Zeta potential measurement showed that both starches and starch phosphates could positively shift the zeta potential of hematite, while starch phosphates had more effects than starches. XPS and MDS indicated that the chemisorption occurred between Fe of hematite surface and C O groups of starch-based depressants. In addition, starch phosphates could adsorb onto the hematite surface through P O groups. MDS also presented that the adsorption strength of starch phosphate was mainly determined by the type and number of generating chelating rings, and the molecular structure of starch significantly affected the formation of chelate rings. The proposed adsorption model insights will significantly promote the development of starch-based depressants for iron ore flotation and other mineral processing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects women of reproductive age. Resistant starch can be fermented by gut microbes then produce short-chain fatty acids (SCFAs). It was reported SCFAs might play a key role in gut microbiota-dependent therapy of PCOS. However, the effects of resistant starch on PCOS symptoms have not yet been investigated. Here, maize starch was acylated with specific SCFAs. Our results indicated that acylated starch can release acetate, propionate, and butyrate into the caecum and colon. Treatment with butylated starch (BS) alleviated abnormal ovarian morphology, metabolic disorders, and sex hormone imbalance in letrozole-treated rats, whereas treatment with acetylated starch and propylated starch did not exhibit such effects. Furthermore, BS stimulated the secretion of peptide tyrosine-tyrosine into the serum by activating a G protein-coupled receptor, GPR41, which further affected disease phenotypes. In addition, compared with caecal microbiota, faecal microbiota was more affected by BS. Butyrate-producing microbes were enriched in faeces after BS treatment and may have helped further to relieve PCOS symptoms. [Display omitted] [ABSTRACT FROM AUTHOR]