GbEXPATR,a species‐specific expansin,enhances cotton fibre elongation through cell wall restructuring

Cotton provides us the most important natural fibre. High fibre quality is the major goal of cotton breeding, and introducing genes conferring longer, finer and stronger fibre from Gossypium barbadense to Gossypium hirsutum is an important breeding strategy. We previously analysed the G. barbadense fibre development mechanism by gene expression profiling and found two homoeologous fibre‐specific α‐expansins from G. barbadense, GbEXPA2 and GbEXPATR. GbEXPA2 (from the D_T genome) is a classical α‐expansin, while its homoeolog, GbEXPATR (A_T genome), encodes a truncated protein lacking the normal C‐terminal polysaccharide‐binding domain of other α‐expansins and is specifically expressed in G. barbadense. Silencing EXPA in G. hirsutum induced shorter fibres with thicker cell walls. GbEXPA2 overexpression in G. hirsutum had no effect on mature fibre length, but produced fibres with a slightly thicker wall and increased crystalline cellulose content. Interestingly, GbEXPATR overexpression resulted in longer, finer and stronger fibres coupled with significantly thinner cell walls. The longer and thinner fibre was associated with lower expression of a number of secondary wall‐associated genes, especially chitinase‐like genes, and walls with lower cellulose levels but higher noncellulosic polysaccharides which advocated that a delay in the transition to secondary wall synthesis might be responsible for better fibre. In conclusion, we propose that α‐expansins play a critical role in fibre development by loosening the cell wall; furthermore, a truncated form, GbEXPATR, has a more dramatic effect through reorganizing secondary wall synthesis and metabolism and should be a candidate gene for developing G. hirsutum cultivars with superior fibre quality.     

LncRNA NONRATT021972 involved the pathophysiologic processes mediated by P2X<Subscript>7</Subscript> receptors in stellate ganglia after myocardial ischemic injury

Adenosine triphosphate (ATP) acts on P2X receptors to initiate signal transmission. P2X₇ receptors play a role in the pathophysiological process of myocardial ischemic injury. Long noncoding RNAs (lncRNAs) participate in numerous biological functions independent of protein translation. LncRNAs are implicated in nervous system diseases. This study investigated the effects of NONRATT021972 small interference RNA (siRNA) on the pathophysiologic processes mediated by P2X₇ receptors in stellate ganglia (SG) after myocardial ischemic injury. Our results demonstrated that the expression of NONRATT021972 in SG was significantly higher in the myocardial ischemic (MI) group than in the control group. Treatment of MI rats with NONRATT021972 siRNA, the P2X₇ antagonist brilliant blue G (BBG), or P2X₇ siRNA improved the histology of injured ischemic cardiac tissues and decreased the elevated concentrations of serum myocardial enzymes, creatine kinase (CK), CK isoform MB (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) compared to the MI rats. NONRATT021972 siRNA, BBG, or P2X₇ siRNA treatment in MI rats decreased the expression levels of P2X₇ immunoreactivity, P2X₇ messenger RNA (mRNA), and P2X₇ protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) in the SG compared to MI rats. NONRATT021972 siRNA treatment prevented the pathophysiologic processes mediated by P2X₇ receptors in the SG after myocardial ischemic injury.     

Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance,immune status and anti-oxidative capacity in early weaned piglets

The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses.     

Improving of lipid productivity of the biodiesel promising green microalga <Emphasis Type="Italic">Chlorella pyrenoidosa</Emphasis> via low-energy ion implantation

High lipid content in microalgae is an essential parameter for adopting of microalgal biomass as a feedstock for biodiesel. Mutation is one approach to obtain desired algal strain with high lipid production. In this study, a mutant strain of Chlorella pyrenoidosa was isolated using 1.5?×?10¹⁵ ions cm^?2 s^?1 of N⁺ ion beam implantation technique, which has been widely used in mutagenesis of agricultural crops. N⁺ implantation slightly improved the growth of the mutant over the corresponding wild strain with significant increase in lipid content (32.4 % higher than the wild strain), which resulted in significant increase in lipid productivity by 35 %. In addition, ion implantation mutagenesis of C. pyrenoidosa resulted in 21.4 % decrease in total saturated fatty acids (SFAs) compared to the wild type, with a noticeable increase in polyunsaturated fatty acids (PUFAs). The increase in PUFAs was due mainly to stimulation of hexadecadienoic acid (C16:2) and octadecadienoic acid (C18:2) production. However, the SFA content of wild and mutant strains was 31.7 and 24.9 % of total fatty acids, respectively, highlighting the oxidative stability of biodiesel produced by both strains according to the European standards. Cultivation of C. pyrenoidosa mutant in selenite enrichment medium for five successive cultivation experiments showed insignificant changes in biomass productivity, lipid content, and lipid productivity alongside the study period, which confirms the genetic stability of the produced mutant. The present study confirmed the feasibility of generation of microalgae mutants with significant high lipid production using ion beam implantation.     

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.     

反硝化基因工程菌株YP4S的构建及对污水除氮特性研究

从养殖场污泥中筛选出菌株YP4,经16S rDNA分子发育树的同源序列比对,确定为克雷伯什菌属(Klebsiella sp.)。由NCBI数据库查编码亚硝酸还原酶(Nir)的基因nirS序列,设计引物,以铜绿假单胞菌PAOI基因组DNA为模板,应用PCR技术扩增目的片段nirS,经过双酶切、克隆和转化,得到重组质粒pYP4S,然后转化野生菌株YP4,构建反硝化基因工程菌YP4S。菌株生长曲线测定表明,工程菌株YP4S与YP4的生长特性基本一致。工程菌株YP4S对模拟污水COD、TN、NH_4^+-N和NO_3^--N具有较高的去除率,YP4S与YP4相比,对NO_2^--N积累的减少量为(32.44±3.96)%,明显减少了NO_2^--N的积累。通过正交试验获得工程菌株YP4S在C/N=10、T=30℃、r=200 r/min和pH=7.0的最佳组合条件下,对模拟污水TN去除率较高。应用工程菌株YP4S处理猪场沉淀池的实际污水,COD、TN、TP、NH_4^+-N和NO_3^--N去除率分别为(95.87±0.82)%、(76.38±3.84)%、(97.13±0.54)%和(75.35±2.57)%,NO_2^--N积累量为(3.31±1.24) mg/L,表明工程菌株YP4S具有较好反硝化作用,对含氮量高的实际污水修复具有潜在的应用前景。