低盐胁迫下松江鲈HSPB1、HSPB7和HSPB11基因的表达变化规律

为了探究小分子热休克蛋白基因HSPB1、HSPB7和HSPB11在松江鲈(Trachidermus fasciatus)应对低盐胁迫过程中的调节作用,本研究基于前期转录组数据,获取3个目标基因的序列信息并进行了系统进化分析,利用实时荧光定量PCR技术检测了3个基因在两种低盐胁迫处理下不同时间点(0 h、12 h、24 h和48 h)在鳃、肠、肾和肝组织中的表达水平。系统进化分析结果表明, HSPB1、HSPB7和HSPB11基因分别聚类形成独立分支;在各基因分支中,松江鲈与已报道的鲈形目、鲤形目和鳉形目等鱼种共同聚为硬骨鱼类分支。在两种低盐胁迫处理下, 3个基因在鳃组织中的表达量均在12h显著升高,而在肠、肾和肝组织中的表达量则呈现不同的变化趋势。肠组织中,HSPB7和HSPB11在盐度渐变低盐胁迫(盐度变化速率1.1/h)下表达量均显著升高, HSPB1表达量在48 h显著降低;盐度骤变低盐胁迫(盐度变化速率27/h)下HSPB1和HSPB7表达量在24 h显著升高, HSPB11表达量显著降低。肾组织中,HSPB1、HSPB7和HSPB11表达量均仅在盐度渐变低盐胁迫24h显著升高;盐度骤变低盐胁迫下HSPB1表达量显著降低, HSPB7和HSPB11表达量则显著升高。肝组织中, HSPB7无表达; HSPB1表达量在盐度渐变低盐胁迫下无显著变化,但在盐度骤变低盐胁迫下则显著升高;HSPB11表达量在两种处理下均显著升高。本研究比较分析了HSPB1、HSPB7和HSPB11基因在松江鲈应对不同低盐胁迫时表达变化规律的异同,相关结果为探讨小分子热休克蛋白在鱼类应激调节过程中的作用及洄游性鱼类适应盐度变化的分子调控机制提供了理论依据。     

饲料脂肪源和碘酸钾对中华鳖稚鳖生长、存活率、肝肠组织形态和脂类代谢的影响

为了比较饲料中添加鱼油、茶籽油、亚麻籽油以及碘酸钾对中华鳖（）稚鳖生长和脂类代谢的影响，本研究配制了4种油脂含量为10%的饲料，分别为鱼油料（FO，对照组）、鱼油+碘酸钾料（FO+PI，碘酸钾添加量为75 mg/kg）、茶籽油料（TO）和亚麻籽油料（LO），饲喂初重为（5.06±0.05）g的中华鳖66 d。FO+PI组和LO组中华鳖稚鳖的存活率显著低于FO组（<0.05）。各组中华鳖稚鳖血浆中葡萄糖、总胆固醇和甘油三酯水平无显著差异（ACACA）的表达水平，上调了中华鳖-499的表达水平（-23b的表达水平（<0.05）。FO+PI组和TO组的稚鳖肝脏细胞内脂滴空泡较少，同时TO显著影响了肠道组织的黏膜褶。结论认为，相比于鱼油组，在饲料中添加10%茶籽油、亚麻籽油和添加75 mg/kg碘酸钾不会引起稚鳖生长差异，但是亚麻籽油和碘酸钾降低了稚鳖的存活率，茶籽油和碘酸钾影响肝脏的脂类代谢。     

不同丝瓜品种褐变相关基因的表达分析

以7种不同丝瓜品种为试验材料,对采后丝瓜果实进行褐变鉴定,测定多酚氧化酶(PPO)活性、过氧化物酶(POD)活性及相关基因的表达量。结果表明:"苏丝3号""苏丝6号""苏丝7号"属于抗褐变品种;"苏丝4号""苏丝5号""苏丝10号"属于耐褐变品种;"苏丝8号"属于严重褐变。从褐变酶POD和PPO变化来看,"苏丝8号"POD活性高达456.7 U·mg-1,抗褐变品种"苏丝3号""苏丝6号""苏丝7号"POD活性均在250 U·mg-1。"苏丝8号"PPO活性为68.2 U·mg-1,"苏丝3号"PPO活性最小,低至25.2 U·mg-1。从褐变基因的变化来看,"苏丝8号"在LcPOD家族基因表达中均高于对照"苏丝3号",其中LcPOD3基因表达量高达5.23,是对照的5倍以上,其它的丝瓜品种LcPOD3基因变化不显著。褐变品种"苏丝8号"在LcPPO基因家族中上调显著,表明"苏丝8号"果实褐变时促进LcPPO基因家族的表达,从而转录翻译成PPO加快果实的褐变。与对照相比,丝瓜褐变基因LCWRKY在"苏丝8号"中上调显著,表明其参与了丝瓜果实采后褐变。其它丝瓜品种LCWRKY上调不显著。     

甜瓜嫩果皮颜色遗传规律研究

为探究甜瓜嫩果皮颜色的遗传规律，以甜瓜嫩果皮颜色为深绿色的S26和青色的S28为亲本材料，通过构建BC1群体，利用卡方测验，分析回交群体BC1的深绿色嫩果皮和青色嫩果皮的分离比例，开展甜瓜嫩果皮的遗传规律分析，以对嫩果皮颜色基因进行初步定位。结果表明：BC1群体表型表现为深绿色和青色2种，且群体比例为1∶1，从而确定颜色性状为单基因控制且深绿色为显性性状。通过分离群体分组分析法（BSA）和混池测序结果可以看出，控制甜瓜嫩果皮颜色的基因位于chr04的端部位置，这为后续基因的精细定位以及克隆提供了研究基础。     

Seaweed polysaccharide mitigates intestinal barrier dysfunction induced by enterotoxigenic Escherichia coli through NF-κB pathway suppression in porcine intestinal epithelial cells

This study aimed to investigate the protective effects and underlying mechanism of seaweed polysaccharide (SWP) on intestinal epithelial barrier dysfunction induced by E. coli in an IPEC-J2 model. A preliminary study was done to screen optimum SWP concentrations by cell viability, cytotoxicity, apoptosis and proliferation evaluation. The regular study was conducted to evaluate the protective effects of SWP against E. coli challenge via the analysis of transepithelial electrical resistance (TEER), tight junction proteins, NF-κB signalling pathway, proinflammatory cytokines and the E. coli adhesion and invasion. Our results show that 4 h E. coli challenge down-regulated tight junction proteins expression, decreased TEER, activated NF-κB signalling pathway and increased proinflammatory response, which indicates that the E. coli infection model was well-established. Pre-treatment with 240 μg/ml SWP for 24 h alleviated the 4 h E. coli -induced intestinal epithelial barrier dysfunction, as evidenced by the up-regulated expression of Occludin, Claudin-1 and ZO-1 at both mRNA and protein level and the increased TEER of IPEC-J2 cells. Pre-incubation with 240 μg/ml SWP for 24 h inhibited the activation of the NF-κB signalling pathway by 4 h E. coli challenge, including the decreased mRNA expression of TLR-4, MyD88, IκBα, p-65, as well as the reduced ratio of protein expression of p-p65/p65. Also, pre-treatment with 240 μg/ml SWP for 24 h decreased proinflammatory response (IL-6 and TNF-α) induced by 4 h E. coli challenge and decreased the E. coli adhesion and invasion. In conclusion, SWP mitigated intestinal barrier dysfunction caused by E. coli through NF-κB pathway in IPEC-J2 cells and 240 μg/ml SWP exhibited better effect. Our results also provide a fundamental basis for SWP in reducing post-weaning diarrhoea of weaned piglets, especially under E. coli -infected or in-feed antibiotic-free conditions.     

Three SNPs within exons of INHA and ACVR2B genes are significantly associated with litter size in Dazu black goats

The aim of this study was to analyse the association between single-nucleotide polymorphisms within INHA and ACVR2B and litter size in Dazu black goats. In total, twenty-two SNPs were genotyped in 190 individuals by SNaPshot and resequencing. The results showed that three SNPs (SNP_1, SNP_12 and SNP_13 in this study) were detected to have significant additive genetic effect on the recorded goat litter size (p < .05). The SNP_1 (NC_030809.1), a non-synonymous substitution of G for T at chr2-g. 28314990 in the exon 2 of INHA gene (NM_001285606.1), resulted in homozygote 2 (HOM2) contributed 0.25 and heterozygote (HET) contributed 0.12 larger litter than homozygote 1 (HOM1). Meanwhile, SNP_12 (Chr22-g. 11721225 A > T) and SNP_13 (Chr22-g. 11721227 A > C) (NC_030829.1) simultaneously mutated at the first and third position of a triplet AAA (lysine, K) in the exon 4 of ACVR2B gene (XM_018066623.1) had estimated genetic effects of HOM1 (0.00) and HOM2 (0.03) larger than HET (−0.12). In conclusion, one SNPs (chr2-g. 28314990 T > G) within the exon 2 of INHA and two SNPs (Chr22-g. 11721225 A > T and Chr22-g. 11721227 A > C) i n the exon 4 of ACVR2B gene were highly recommended as candidate markers of litter size in Dazu black goats. A large-scale association study to assess the impact of these variants on litter size is still necessary.     

禽致病性大肠杆菌luxS和rbsC双基因缺失株的构建及其生物特性分析

禽致病性大肠杆菌(APEC)能引起家禽严重的呼吸系统和全身性疾病,由于APEC耐药菌株的不断出现迫使新型抗菌方式的研发迫在眉睫。本研究旨在评价APEC的luxS和rbsC双缺失的突变株作为减毒疫苗候选株的潜力,通过在APEC分离株DE17的单基因缺失株DE17ΔluxS的基础上,利用Red重组系统构建双基因缺失株DE17ΔluxSΔrbsC,并对其生物学特性进行了分析。结果显示:rbsC的缺失不影响DE17ΔluxS的生长特性和生物被膜形成能力,但运动性显著降低;与DE17ΔluxS相比,DE17ΔluxSΔrbsC的黏附能力和入侵能力分别降至46.92%和28.78%;半数致死量(LD50)结果显示,毒力下降了115.5倍;肝脏、脾脏和血液中的载菌量分别下降了3.63倍、79.20倍和2124.41倍。根据以上结果推测,rbsC基因的缺失会进一步降低DE17ΔluxS的毒力,本文为评价DE17ΔluxSΔrbsC株减毒机制提供参考。     

Comparative analysis of genetic effects of wheat‐Dasypyrum villosum translocations T6V#2S·6AL and T6V#4S·6DL

Wheat‐Dasypyrum villosum translocations T6V#2S·6AL and T6V#4S·6DL, carriers of Pm21 and PmV, respectively, confer high resistance to wheat powdery mildew. For better understanding of the difference in genetic effect between them, a RIL population was constructed based on the cross between “Yangmai 18” carrying T6V#2S·6AL and “Yangmai 22” carrying T6V#4S·6DL. Analysis of distribution of the translocations showed that T6V#2S·6AL is much more transmittable than T6V#4S·6DL. By comparing their effects on main agronomic traits, we firstly found that T6V#2S·6AL contributes greatly to top spikelet fecundity, but causes a decrease of 6.7%–10.5% of spike number. No stable effects of T6V#4S·6DL on agronomic traits were found, except for positive effect on plant height. Excitingly, a new recombinant, T6V#4S‐6V#2S·6AL carrying PmV, was screened and proved to have a higher transmission rate than the original translocation T6V#4S·6DL, which will greatly promote the utilization of PmV. The above conclusions of this research will provide important guidance for utilization of Pm21 and PmV more effectively, in wheat powdery mildew resistance breeding.     

An isolate of Wheat streak mosaic virus from foxtail overcomes Wsm2 resistance in wheat

Wheat streak mosaic virus (WSMV) is an economically important pathogen of wheat (Triticum aestivum) causing major yield losses in regions where severe infection occurs. To detect the presence of any new virus or new WSMV isolates, green foxtail (Setaria viridis) plants exhibiting virus-like symptoms were sampled in a summer-fallowed wheat field at the Agricultural Research Center-Hays, Kansas State University, Hays, Kansas. These plants were tested serologically for four wheat viruses: WSMV, Triticum mosaic virus (TriMV), High Plains wheat mosaic virus (HPWMoV) and Foxtail mosaic virus (FoMV). Among 38 plant samples exhibiting virus-like symptoms, 29 contained WSMV as indicated by ELISA. Four isolates from samples with relatively strong reactions were transferred to healthy wheat seedlings by mechanical inoculation in a growth chamber for pathogenicity testing. Three isolates were avirulent to a wheat variety RonL, which contains Wsm2, a gene providing temperature-sensitive resistance to currently prevalent isolates of WSMV. However, one isolate, KSH294, was able to infect RonL and showed more virulence on two other varieties/lines containing Wsm2. Further sequence and phylogenetic analysis of KSH294 confirmed that this isolate displays a sequence homology with WSMV, but has sequence differences making it distinct from previously identified WSMV isolates included in the phylogenetic analysis.