粪肠球菌生长曲线的测定及其对小鼠脑组织的影响

为测定致羔羊脑炎粪肠球菌（Enterococcus faecalis）的生长曲线，寻求一种快速而准确的方法测定不同生长时期粪肠球菌数量，并客观评价其毒性强弱及其对小鼠脑组织的影响，试验采用平板菌落计数法和OD-Monitor振荡比浊法（D_λ值法）测定粪肠球菌的生长曲线，探究该菌在合适时间段内的吸光值（D_{600 nm}）与平板菌落计数法测定的活菌数（CFU）的关系。用粪肠球菌感染小鼠，观察记录小鼠的死亡情况，最后采用Karber法计算粪肠球菌感染小鼠的半数致死量（LD₅₀）。用LD₅₀的剂量感染小鼠，及时采集死亡小鼠脑组织，未死亡的小鼠72 h后全部剖杀取脑组织，一部分做涂片染色，制作病理切片，观察病理变化；一部分进行培养，用于PCR方法进行细菌的回收鉴定。结果显示，用两种方法测定此株粪肠球菌的生长曲线基本一致，在2~8 h生长迅速，为对数生长期，8~14 h生长缓慢，为稳定期，14 h之后死亡数增加，进入衰亡期；对12 h粪肠球菌D_{600 nm}与CFU的关系进行探讨，成功建立回归方程：y=20.769x-1.3422，R²=0.997；其感染小鼠的LD₅₀为7.77×10¹¹个活菌。以此剂量感染小鼠，脑组织涂片染色和培养染色，均能看到革兰氏阳性球菌；PCR结果显示，均出现了大小为112 bp的条带。对脑组织进行病理学观察发现该菌可导致脑组织充血、出血、形成微血栓，脑膜充血。通过生长曲线和其D_{600 nm}与CFU关系的建立，可实时监测粪肠球菌数量，为后期更深入研究粪肠球菌穿越血脑屏障的机制奠定重要的理论基础。     

低聚半乳糖干预缓解肠道炎症的研究进展

肠道炎症已成为我国社会健康的难题和挑战，其发病率在我国迅速增长。肠道炎症发病原因复杂，目前尚缺乏有效的缓解药物，因此加强肠道炎症有效缓解物质的研发至关重要。低聚半乳糖（galactooligosaccharide，GOS）是一种食疗益生性较优的乳源功能性低聚糖，能够有效促进肠道内益生菌的增殖，改变肠道菌群结构，刺激免疫应答，进而改善肠黏膜屏障功能，缓解肠道炎症。本文综述近年来国内外有关肠道炎症及GOS干预缓解肠道炎症作用的研究进展，并对其应用前景进行展望，为此领域的研究提供科学依据。     

Regulatory role of l-proline in fetal pig growth and intestinal epithelial cell proliferation

l-proline (Pro) is a precursor of ornithine, which is converted into polyamines via ornithine decarboxylase (ODC). Polyamines plays a key role in the proliferation of intestinal epithelial cells. The study investigated the effect of Pro on polyamine metabolism and cell proliferation on porcine enterocytes in vivo and in vitro. Twenty-four Huanjiang mini-pigs were randomly assigned into 1 of 3 groups and fed a basal diet that contained 0.77% alanine (Ala, iso-nitrogenous control), 1% Pro or 1% Pro + 0.0167% α-difluoromethylornithine (DFMO) from d 15 to 70 of gestation. The fetal body weight and number of fetuses per litter were determined, and the small and large intestines were obtained on d 70 ± 1.78 of gestation. The in vitro study was performed in intestinal porcine epithelial (IPEC-J2) cells cultured in Dulbecco''s modified Eagle medium-high glucose (DMEM-H) containing 0 μmol/L Pro, 400 μmol/L Pro, or 400 μmol/L Pro + 10 mmol/L DFMO for 4 d. The results showed that maternal dietary supplementation with 1% Pro increased fetal weight; the protein and DNA concentrations of the fetal small intestine; and mRNA levels for potassium voltage-gated channel, shaker-related subfamily, member 1 (Kv1.1) in the fetal small and large intestines (P < 0.05). Supplementing Pro to either gilts or IPEC-J2 cells increased ODC protein abundances and polyamine concentrations in the fetal intestines and IPEC-J2 cells (P < 0.05). In comparison with the Pro group, the combined administration of Pro and DFMO reduced the expression of ODC protein and spermine concentration in the fetal intestine, as well as the concentrations of putrescine, spermidine and spermine in IPEC-J2 cells (P < 0.05). Meanwhile, the percentage of cells in the S-phase and the mRNA levels of proto-oncogenes c-fos and c-myc were increased in response to Pro supplementation, whereas depletion of cellular polyamines with DFMO increased tumor protein p53 (p53) mRNA levels (P < 0.05). Taken together, dietary supplementation with Pro improved fetal pig growth and intestinal epithelial cell proliferation via enhancing polyamine synthesis.     

乙酰羟酸合酶抑制剂类除草剂的植物抗性机制

乙酰羟酸合酶(AHAS)抑制剂类除草剂已被广泛用于农业生产,然而使用过程中可能对部分敏感农作物产生药害,因此创制对不同类别除草剂具有抗性的一系列作物新品种至关重要。本文将从AHAS抑制剂类除草剂的类别与特点、AHAS靶酶的特性及其在支链氨基酸合成中的作用、除草剂的靶标抗性与非靶标抗性机制等方面分析国内外研究现状与未来发展动态,以期为农作物除草剂抗性性状的遗传改良和开发应用提供参考。     

The effects of various plant protection methods on the development of Zymoseptoria tritici and Cephalosporium gramineum,grain yield and protein profile

Septoria leaf blotch progresses rapidly, leading to the development of Zymoseptoria titici forms resistant to fungicides. Cephalosporium stripe is caused by Cephalosporium gramineum. The aim of this study was to evaluate the effectiveness of selected pesticides in limiting the symptoms of both diseases on winter wheat leaves, and to determine their influence on grain yield and the content and composition of protein fractions in wheat kernels. Propiconazoles were most effective in inhibiting the development of Septoria leaf blotch (symptoms were reduced from 54.7% to 78.6%). Strobilurins were less effective due to the presence of isolates with the G143A mutation. Symptoms of Cephalosporium stripe were rarely observed, and protective treatments did not reduce their severity. The highest content of grain protein (14.81%) was found in plants most intensely protected with the fungicides containing fenpropimorph, pyraclostrobin and epoxiconazole. The principal component analysis revealed that the plant protection method influenced the grain protein profile. The accumulation of HMW glutenins and α/β gliadins was mutually interrelated and higher in high-input treatments; control grain was characterized by close relationships between ω-gliadins, LMW glutenins, albumins and globulins, whereas low-input treatments influenced mostly γ-gliadins.     

Identification of an H1N1 subtype of swine influenza virus and serological analysis

To investigate the epizootic of swine influenza virus(SIV), 60 nasal swabs were collected from a clinical cases of pig farm in Tai'an City, Shandong Province of China in April 2017. SIV was isolated by inoculating into 10-day-old Special Pathogen Free embryonated eggs and the whole genome was sequenced. An H1N1 subtype SIV was isolated and designated as A/swine/Shandong/TA04/2017(H1N1). Phylogenetic analysis showed that apart from the polymerase A(PA) fragment belonging to the 2009 pandemic H1N1 branch, seven genome segments belonged to avian-like H1N1 influenza virus lineage. The cleavage site sequence of the hemagglutinin(HA) protein was PSIQSR↓G, which is a typical molecular biological characteristic. Five potential N-glycosylation sites(N14, N26, N277, N484 and N543) were found in the HA gene. To further investigate the epidemiology of SIV in this farm, the 995 serum samples were assessed with EAH1N1 2009 pandemic H1N1 and H3 N2 antigens. The results showed that the total positive rate was 65.43%. The positive rates of single virus infection detected by EAH1N1, 2009 pdmH1N1 and H3 N2 for serum HI(Hemagglutination inhibition) were 48.35, 30.85 and 7.47%, respectively. The results showed that SIV in Shandong Province has been reassorted in some segments and the SIV-positive rate was high on the SIV outbreak farm. These data provide evidence of an epizootic of SIV.     

褪黑素诱导小豆抗锈病机理的初步研究

为明确外源褪黑素诱导小豆抗锈性的作用及机理,以感病小豆品种‘宝清红’为材料,采用叶面喷施不同浓度褪黑素激发处理小豆真叶,而后对真叶挑战接种锈菌夏孢子,结果表明,低浓度(11.61 mg/L)褪黑素可显著提升小豆对锈病的抗性。夏孢子萌发试验表明,褪黑素对夏孢子萌发及芽管生长无显著抑制作用,表明褪黑素无抑菌活性。进一步的基因表达分析发现,与对照相比,褪黑素激发诱导了水杨酸(SA)通路关键基因NPR1于接种后24 h显著上调表达,且病程相关蛋白PR1、几丁质酶(CHI)、β-1,3-葡聚糖酶(GLU)及PR5均于接种后24～120 h被显著诱导表达,说明褪黑素可能通过诱导NPR1表达,进而激活下游PR蛋白的高水平应答,使感锈病小豆品种获得对锈病的抗性。     

硅藻土对5种储粮害虫和不同磷化氢抗性水平杂拟谷盗防治效果的研究

为初步了解硅藻土对储粮害虫的防治效果以及与害虫磷化氢抗性发生发展的关系, 本研究采用直接拌粮法(设置剂量梯度为0?0.2?0.4?0.6 g/kg和 0.8 g/kg)测定硅藻土对赤拟谷盗?杂拟谷盗?锈赤扁谷盗?谷蠹?玉米象的防治效果, 以及磷化氢抗性杂拟谷盗(抗性倍数为 2.3~144.7)对硅藻土的敏感性差异; 除此之外, 本研究还分析了0.4 g/kg硅藻土在 4 种粮食(小麦?玉米?大豆?稻谷)中对赤拟谷盗的杀虫效果?研究结果表明:一定剂量(0.2~0.8 g/kg)的硅藻土均能够在一定时间内有效杀死上述 5种储粮害虫, 不同储粮害虫对硅藻土的敏感性存在显著差异(P<0.05), 其中杂拟谷盗对硅藻土的耐受性最强, 玉米象对硅藻土最为敏感?除个别品系外, 不同磷化氢抗性品系的杂拟谷盗对硅藻土的敏感性不存在显著差异(P>0.05), 且与磷化氢抗性无关; 硅藻土在不同粮食中对害虫的作用效果存在显著性差异(P<0.05)(处理 7 d后, 死亡率为 13%~98%), 其中在大豆中对赤拟谷盗的杀虫效果最强, 在玉米中对其作用效果不明显?因此本研究得出结论:硅藻土对主要储粮害虫均具有一定的防治作用, 且对抗磷化氢的杂拟谷盗具有良好的致死效果?因此, 硅藻土具备成为储粮害虫防治及其磷化氢抗性治理药剂的潜力?     

水稻对稻飞虱抵御机制研究

为更好地利用水稻自身抵御能力遏制稻飞虱为害,综述了水稻抵御稻飞虱的物理、生化效应和机制的研究现状。水稻抵御稻飞虱的物理机制包括宏观的水稻叶脉间距、宽度,钩毛和纤细毛密度、长度,硅含量和微观的粗纤维、胼胝质含量及叶绿体膜稳定性;生化机制涉及水分、可溶性糖、叶绿素、游离氨基、酶物质活性及挥发物的含量。国内外虽广泛涉及水稻自身固有的物理结构及体内生理生化物质对稻飞虱的抵御效应研究,但其分子机理研究较为匮乏,尚需深入系统的研究。     

保护地黄瓜新品种唐杂6 号的选育

唐杂6 号是以雌性系S16 为母本，以自交系S26 为父本配制的强雌型黄瓜一代杂种。生长势强，商品瓜短棒状， 瓜长12～14 cm，横径4.0～4.3 cm，非特异性环境下雌花率95% 以上，瓜皮嫩绿有光泽，白刺，刺瘤稀小，平均单瓜质量 131.8 g 左右，高抗霜霉病，抗细菌性角斑病，耐白粉病；春保护地栽培平均产量可达8 000 kg·（667 m²） ^-1，秋冬保护地栽 培产量可达6 500 kg·（667 m²） ^-1；适合河北、北京、天津及东北地区春、秋保护地种植。