Advances in research on signal molecules regulating biofilms

World Journal of Microbiology and Biotechnology - Antibiotic and arsenic (As) contaminations are worldwide public health problems. Previously, the bacterial ABC-type efflux protein MacAB reportedly...     

Genetic mapping of folate QTLs using a segregated population in maize

As essential B vitamin for humans, folates accumulation in edible parts of crops, such as maize kernels, is of great importance for human health. But its breeding is always limited by the prohibitive cost of folate profiling. The molecular breeding is a more executable and efficient way for folate fortification, but is limited by the molecular knowledge of folate regulation. Here we report the genetic mapping of folate quantitative trait loci (QTLs) using a segregated population crossed by two maize lines, one high in folate (GEMS31) and the other low in folate (DAN3130). Two folate QTLs on chromosome 5 were obtained by the combination of F₂ whole-exome sequencing and F₃ kernel-folate profiling. These two QTLs had been confirmed by bulk segregant analysis using F₆ pooled DNA and F₇ kernel-folate profiling, and were overlapped with QTLs identified by another segregated population. These two QTLs contributed 41.6% of phenotypic variation of 5-formyltetrahydrofolate, the most abundant storage form among folate derivatives in dry maize grains, in the GEMS31×DAN3130 population. Their fine mapping and functional analysis will reveal details of folate metabolism, and provide a basis for marker-assisted breeding aimed at the enrichment of folates in maize kernels.     

UPA2 and ZmRAVL1: Promising targets of genetic improvement of maize plant architecture

正Maize (Zea mays ssp. mays) is a major staple crop, with the highest tonnage among cereal crops worldwide(FAO 2014). Over the past century, maize yields have increased about 8-fold in the US central Corn Belt (from1,287 kg/ha in the 1930s to 11,084 kg/ha in 2017, http://m entary     

The Water-Soluble Pool in Biochar Dominates Maize Plant Growth Promotion Under Biochar Amendment

Although amending biochar into agricultural soils has been regarded as an effective measure to improve crop productivity, it remains unclear why biochar increases crop yield. The objective of this study was to compare the relative contribution of different biochar components in crop growth promotion. Three biochar components were separated: (i) water-soluble biochar extract (BE), (ii) mineral nutrients from biochar ash (BA), and (iii) washed biochar residue (WB). Two soils (Anthrosol and Primosol) with distinctly different organic carbon content, soil texture and land use were amended with the three biochar components and their effects on maize (Zea mays L.) growth were tested in a pot experiment. We hypothesized that (1) plant grown in the Anthrosol benefitted more from the water-soluble compounds of biochar than from its mineral nutrients or washed residue, since the soil is already fertile and has a good structure; (2) plant grown in the Primosol benefitted more from the mineral nutrients of biochar and its washed residual, since the soil is nutrient-poor and has a poor structure. The addition of biochar and its three components increased maize aboveground biomass for both soils. In the Anthrosol, BE, BA, and WB increased the aboveground biomass by 41.6%, 32.7%, and 27.1%; in the Primosol, they increased the aboveground biomass by 41.3%, 24.4%, and 18.2%, respectively. BE had the highest plant growth-promoting effect compared to the other two biochar components, which was regardless of soil condition. In addition, the biomass, total volume, surface area, and number of maize root tips under BE amendment were significantly enhanced, particularly the fine roots (< 0.2 mm in diameter). And a strong positive correlation was observed between maize aboveground biomass and the total length of the fine roots. The results demonstrated that the water-soluble compounds present in biochar, in addition to the mineral nutrients and the washed biochar residue, dominate the plant growth promotion under both soil conditions.

     

Design,Synthesis and Biological Activity of (20S,21S)‐7‐Cyclohexyl‐21‐fluorocamptothecin Carbamates as Potential Antitumor Agents

(20S,21S)‐7‐Cyclohexyl‐21‐fluorocamptothecin was discovered by a fluorine drug design strategy with potent antitumor activity and increased metabolic stability. In continuous efforts to find novel antitumor agents derived from natural product camptothecin, 20‐carbamates of the active compound (20S,21S)‐7‐cyclohexyl‐21‐fluorocamptothecin have been designed and synthesized. Among them, one compound with the diethylamino group showed greater antiproliferative activity than the other 20‐carbamate derivatives. The following biological activity assays indicated that the above compound is a valuable lead compound with excellent Topo I inhibitory activity and solution stability.     

Neural Mechanisms of Selective Attention in Children with Amblyopia

Previous studies have indicated that amblyopia might affect children''s attention. We recruited amblyopic children and normal children aged 9–11 years as study subjects and compared selective attention between the two groups of children. Chinese characters denoting colors were used in the Stroop task, and the event-related potential (ERP) was analyzed. The results show that the accuracy of both groups in the congruent condition was higher than the incongruent condition, and the reaction time (RT) of amblyopic children was longer. The latency of the occipital P1 in the incongruent condition was shorter than the neutral condition for both groups; the peak of the occipital P1 elicited by the incongruent stimuli in amblyopic children was higher. In both groups, the N1 peak was higher in the occipital region than frontal and central regions. The N1 latency of normal children was shorter in the congruent and neutral conditions and longer in the incongruent condition; the N1 peak of normal children was higher. The N270 latencies of normal children in the congruent and neutral conditions were shorter; the N270 peak was higher in parietal and occipital regions than frontal and central regions for both groups. The N450 latency of normal children was shorter; in both groups, the N450 average amplitude was significantly higher in the parietal region than central and frontal regions. The accuracy was the same for both groups, but the response of amblyopic children was significantly slower. The two groups showed differences in both stages of the Stroop task. Normal children showed advantages in processing speed on both stimulus and response conflict stages.Brain regions activated during the Stroop task were consistent between groups, in line with their age characteristics.     

信号分子调控细菌生物被膜形成的分子机制

细菌生物被膜(Bacterial biofilm,BF)是黏附于机体黏膜或生物材料表面、由细菌及其分泌的多聚糖、蛋白质和核酸等组成的被膜状生物群体,是造成持续性感染的重要原因之一。细菌在生长繁殖时会产生一些次级代谢产物,部分会作为生物信号分子在细胞内或细胞间传递信息,使细菌在多细胞水平协调统一相互配合,以完成一些重要的生理学功能,如生物发光、BF的形成、运动与固定态生活方式的转换等。信号分子在BF形成过程中起着重要的调控作用。文中从密度感应系统(Quorum-sensing systems,QS)、环二鸟苷酸(Cyclic diguanylate,c-di-GMP)、双组分系统(Two-component systems,TCS)和sRNA等方面介绍影响BF形成的相关信号分子,重点对BF形成过程中的信号分子调控机制进行概述,这对于深入揭示信号分子调控BF形成的机制十分必要。     

An ultra-high density bin-map for rapid QTL mapping for tassel and ear architecture in a large F2 maize population

Background

Understanding genetic control of tassel and ear architecture in maize (Zea mays L. ssp. mays) is important due to their relationship with grain yield. High resolution QTL mapping is critical for understanding the underlying molecular basis of phenotypic variation. Advanced populations, such as recombinant inbred lines, have been broadly adopted for QTL mapping; however, construction of large advanced generation crop populations is time-consuming and costly. The rapidly declining cost of genotyping due to recent advances in next-generation sequencing technologies has generated new possibilities for QTL mapping using large early generation populations.

Results

A set of 708 F₂ progeny derived from inbreds Chang7-2 and 787 were generated and genotyped by whole genome low-coverage genotyping-by-sequencing method (average 0.04×). A genetic map containing 6,533 bin-markers was constructed based on the parental SNPs and a sliding-window method, spanning a total genetic distance of 1,396 cM. The high quality and accuracy of this map was validated by the identification of two well-studied genes, r1, a qualitative trait locus for color of silk (chromosome 10) and ba1 for tassel branch number (chromosome 3). Three traits of tassel and ear architecture were evaluated in this population, a total of 10 QTL were detected using a permutation-based-significance threshold, seven of which overlapped with reported QTL. Three genes (GRMZM2G316366, GRMZM2G492156 and GRMZM5G805008) encoding MADS-box domain proteins and a BTB/POZ domain protein were located in the small intervals of qTBN5 and qTBN7 (~800 Kb and 1.6 Mb in length, respectively) and may be involved in patterning of tassel architecture. The small physical intervals of most QTL indicate high-resolution mapping is obtainable with this method.

Conclusions

We constructed an ultra-high-dentisy linkage map for the large early generation population in maize. Our study provides an efficient approach for fast detection of quantitative loci responsible for complex trait variation with high accuracy, thus helping to dissect the underlying molecular basis of phenotypic variation and accelerate improvement of crop breeding in a cost-effective fashion.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-433) contains supplementary material, which is available to authorized users.