Engineering of Acetate Recycling and Citrate Synthase to Improve Aerobic Succinate Production in Corynebacterium glutamicum

Corynebacterium glutamicum lacking the succinate dehydrogenase complex can produce succinate aerobically with acetate representing the major byproduct. Efforts to increase succinate production involved deletion of acetate formation pathways and overexpression of anaplerotic pathways, but acetate formation could not be completely eliminated. To address this issue, we constructed a pathway for recycling wasted carbon in succinate-producing C. glutamicum. The acetyl-CoA synthetase from Bacillus subtilis was heterologously introduced into C. glutamicum for the first time. The engineered strain ZX1 (pEacsA) did not secrete acetate and produced succinate with a yield of 0.50 mol (mol glucose)⁻¹. Moreover, in order to drive more carbon towards succinate biosynthesis, the native citrate synthase encoded by gltA was overexpressed, leading to strain ZX1 (pEacsAgltA), which showed a 22% increase in succinate yield and a 62% decrease in pyruvate yield compared to strain ZX1 (pEacsA). In fed-batch cultivations, strain ZX1 (pEacsAgltA) produced 241 mM succinate with an average volumetric productivity of 3.55 mM h⁻¹ and an average yield of 0.63 mol (mol glucose) ⁻¹, making it a promising platform for the aerobic production of succinate at large scale.     

H2S catalysed by CBS regulates testosterone synthesis through affecting the sulfhydrylation of PDE

Testosterone deficiency resulted in increased mortality in men. Our previous work found that hydrogen sulphide (H₂S) significantly alleviated the spermatogenesis disorder. To investigate whether H₂S could regulate testosterone synthesis and the relative signalling pathways. Disorder model of testosterone synthesis was constructed in vitro and in vivo. The cell viability was detected using CCK-8 method. The concentration of H₂S and testosterone were examined using ELISA kits. The relative mRNA and protein expression of CBS, PDE4A, PDE8A and proteins related to testosterone synthesis were detected by RT-qPCR and western blotting. PAS staining was used to detect the inflammatory status of testis. The sulfhydryl level of PDE4A and PDE8A was determined by Biotin Switch Technique. CBS overexpression inhibited while knockdown promoted LPS + H₂O₂ induced injury in testosterone synthesis of MLTC-1 cells, though regulating the level of H₂S. The LPS + H₂O₂ induced inhibition on cAMP and p-PKA was recovered by CBS overexpression, while addition of the specific inhibitor of PKA had opposite effects. CBS overexpression alleviated the inflammation status in testis and promoted the expression of StAR, P450scc, P450c17 and 3β-HSD. CBS could also exhibit its protective role through promoting sulfhydrylation of PDE4A and PDE8A. H₂S catalysed by CBS could recover testosterone synthesis in vitro and in vivo through inhibiting PDE expression via sulfhydryl modification and activating cAMP/PKA pathway.     

SARS-CoV-2 envelope protein causes acute respiratory distress syndrome (ARDS)-like pathological damages and constitutes an antiviral target

Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology     

球孢白僵菌对四种十字花科蔬菜害虫的兼控潜力评价

研究了分离自小猿叶甲的一株球孢白僵菌(Beauveria bassiana(SCAU-BB01D))对十字花科蔬菜4种非目标害虫烟粉虱Bemisia tabaci、小菜蛾Plutella xylostella、黄曲条跳甲Phyllotreta striolata和菜缢管蚜Lipaphis erysimi的致病能力。结果表明,在实验室条件下,该菌株对以上4种害虫均有不同程度的侵染力。1×108孢子/mL的白僵菌悬浮液对1,2,3,4龄烟粉虱若虫的侵染率分别为84.88,86.81,55.94和38.78%;对小菜蛾2,3和4龄幼虫的侵染率为67,59和44%;对黄曲条跳甲幼虫和成虫分别为63%和60%;对菜缢管蚜成蚜和若蚜的侵染率分别为44%和35%。通过机率值分析,得出该菌株对烟粉虱1~4龄若虫的LT50分别为4.14,3.78,6.24和7.59 d;对小菜蛾2~4龄幼虫的LT50分别为7.29,8.16和9.82d;对黄曲条跳甲成虫和幼虫的LT50分别为11.22和8.11 d;对菜缢管蚜成蚜和若蚜的LT50分别为11.01和12.15 d。说明该球孢白僵菌菌株对烟粉虱、小菜蛾和黄曲条跳甲3种非目标害虫具有一定的兼控作用,在蔬菜害虫的生物防治中具一定的应用潜力。     

芦苇与入侵植物互花米草的光合特性比较

以上海崇明东滩湿地外来入侵植物互花米草与本地种芦苇为研究对象,对它们的光合特性进行了比较研究,结果表明:(1)与芦苇相比,互花米草具有更高的表观量子效率(AQY)、CO2羟化效率(CE)和最大净光合速率(pmax);(2)生长季节初期,互花米草午间时段的光合、气孔导度和蒸腾速率均高于芦苇,各指标与光、温的变化基本一致;(3)互花米草的净光合速率曲线呈“单峰”型,测定指标在强光合辐射、高温条件下迅速上升,芦苇则表现出明显的“午休”现象;(4)在生长季节初期(5月份)和活跃期(9月份),互花米草的净光合速率显著高于芦苇,而在生长季节后期(11月份)则低于芦苇。该项研究有利于解释互花米草生长迅速,生产力高,竞争性强的生理生态学特性。     

比哈小爪螨实验种群生命表的研究

本文研究了比哈小爪螨5个温度梯度的实验种群生命表.结果表明15 ℃时内禀增长率和周限增长率均最小,分别为0.0235和1.0238,种群倍增时间最长(29.47 d);35 ℃时内禀增长率和周限增长率均最大,分别为0.3069和0.3592,种群倍增时间最短(2.26 d),说明高温有利于该螨种群的增长.25 ℃时净增殖率最大(56.30).35 ℃的世代生长周期最短(11.97 d).15 ℃时其寿命最长(98.90±20.77 d),35 ℃时寿命最短(19.00±3.11 d).最高平均产卵量71.60粒/雌和最高日平均产卵量4.10粒/雌/天均在25 ℃时出现.15 ℃时平均产卵量最低(8.80粒/雌),日平均产卵量仅有0.34粒/雌/天.最大日产卵量出现在35 ℃时(12.00粒/雌/天).     

抗人尿道高分化鳞癌单克隆抗体的研制

用本室建立的人尿道高分化鳞状上皮癌细胞株(Hus-98)免疫Balb/C小鼠,通过细胞杂交技术及ELISA方法进行筛选,SP免疫组织化学方法进行鉴定,获得10株能稳定分泌、选择性强、效价高的杂交瘤细胞株;同时从乳腺癌组织中提出肿瘤相关抗原行免疫印记实验(Western-blot)。结果6株经4次克隆能稳定分泌抗体Ig,免疫组化显示这些抗体是针对来源于上皮的鳞癌、腺癌细胞膜和细胞浆的,而癌旁正常组织及胎儿组织呈阴性反应;通过western-blot结果显示肿瘤相关抗原分子量为46.414kb。     

Allozymic, morphological, and phenological diversity in cultivatedLuffa acutangula (Cucurbitaceae) from China, Laos, and Nepal, and Allozyme Divergence betweenL. acutangula andL. Aegyptiaca

The immature fruits of domesticated Luffa acutangula (L.) Roxb. are a common vegetable in Asia and India. To learn more about traditional cultivars, accessions were collected from southern Yunnan Province of China, northern Laos, and southeastern Nepal, and assessed for various parameters of genetic diversity. The size and shape of the fruits and seeds varied considerably. A form that we found cultivated only in Nepal bore clusters of small fruits that are produced by hermaphrodite flowers. Plants produced male flowers first, and the first node to bear flowers varied from the second to the twenty-seventh. Twenty-nine allozyme loci were assayed. Within L. acutangula one allozyme locus was polymorphic. Luffa acutangula andL. aegyptiaca are fixed for different alleles at nine loci, indicating that they are completely reproductively isolated from each other.