Safety and immunogenicity of a new glycoengineered vaccine against Acinetobacter baumannii in mice

Acinetobacter baumannii poses a serious threat to human health, mainly because of its widespread distribution and severe drug resistance. However, no licensed vaccines exist for this pathogen. In this study, we created a conjugate vaccine against A. baumannii by introducing an O-linked glycosylation system into the host strain. After demonstrating the ability of the vaccine to elicit Th1 and Th2 immune responses and observing its good safety in mouse a model, the strong in vitro bactericidal activity and prophylactic effects of the conjugate vaccine against infection were further demonstrated by evaluating post-infection tissue bacterial loads, observing suppressed serum pro-inflammatory cytokine levels. Additionally, the broad protection from the vaccine was further proved via lethal challenge with A. baumannii. Overall, these results indicated that the conjugate vaccine could elicit an efficient immune response and provide good protection against A. baumannii infection in murine sepsis models. Thus, the conjugate vaccine can be considered as a promising candidate vaccine for preventing A. baumannii infection.     

SIRT3 deficiency decreases oxidative metabolism capacity but increases lifespan in male mice under caloric restriction

Mitochondrial NAD⁺‐dependent protein deacetylase Sirtuin3 (SIRT3) has been proposed to mediate calorie restriction (CR)‐dependent metabolic regulation and lifespan extension. Here, we investigated the role of SIRT3 in CR‐mediated longevity, mitochondrial function, and aerobic fitness. We report that SIRT3 is required for whole‐body aerobic capacity but is dispensable for CR‐dependent lifespan extension. Under CR, loss of SIRT3 (Sirt3 ^−/− ) yielded a longer overall and maximum lifespan as compared to Sirt3 ^+/+ mice. This unexpected lifespan extension was associated with altered mitochondrial protein acetylation in oxidative metabolic pathways, reduced mitochondrial respiration, and reduced aerobic exercise capacity. Also, Sirt3 ^−/− CR mice exhibit lower spontaneous activity and a trend favoring fatty acid oxidation during the postprandial period. This study shows the uncoupling of lifespan and healthspan parameters (aerobic fitness and spontaneous activity) and provides new insights into SIRT3 function in CR adaptation, fuel utilization, and aging.     

Structural basis for the unique multifaceted interaction of DPPA3 with the UHRF1 PHD finger

Ubiquitin-like with PHD and RING finger domain-containing protein 1 (UHRF1)-dependent DNA methylation is essential for maintaining cell fate during cell proliferation. Developmental pluripotency-associated 3 (DPPA3) is an intrinsically disordered protein that specifically interacts with UHRF1 and promotes passive DNA demethylation by inhibiting UHRF1 chromatin localization. However, the molecular basis of how DPPA3 interacts with and inhibits UHRF1 remains unclear. We aimed to determine the structure of the mouse UHRF1 plant homeodomain (PHD) complexed with DPPA3 using nuclear magnetic resonance. Induced α-helices in DPPA3 upon binding of UHRF1 PHD contribute to stable complex formation with multifaceted interactions, unlike canonical ligand proteins of the PHD domain. Mutations in the binding interface and unfolding of the DPPA3 helical structure inhibited binding to UHRF1 and its chromatin localization. Our results provide structural insights into the mechanism and specificity underlying the inhibition of UHRF1 by DPPA3.     

Comparative Transcriptome Analyses Reveal Genes Related to Spine Development in Cucumber (<i>Cucumis sativus</i>)

Fruit spine is an important quality trait of cucumber. To better understand the molecular basis of cucumber spine development and function, RNA-Seq was performed to identify differentially expressed genes (DEGs) in fruit spines of different development stages, namely, 8 days before anthesis (SpBA8), anthesis (SpA) and 8 days after anthesis (SpAA8). Stage-wise comparisons obtained 2,259 (SpBA8 vs. SpA), 4,551 (SpA vs. SpAA8), and 5,290 (SpBA8 vs. SpAA8) DEGs. All the DEGs were classified into eight expression clusters by trend analysis. Among these DEGs, in addition to the Mict, Tril, CsTTG1, CsMYB6, NS, and Tu genes that have been reported to regulate fruit spine formation, we found that the CsHDG11, CsSCL8, CsSPL8, CsZFP6 and CsZFP8 may also be involved in spine development in cucumber. Our study provides a theoretical basis for further research on molecular mechanisms of spine development in cucumber.     

Mercuric chloride induced brain toxicity in mice: The protective effects of puerarin-loaded PLGA nanoparticles

Mercury is a toxic, environmentally heavy metal that can cause severe damage to all organs, including the nervous system. The functions of puerarin include antioxidant, anti-inflammatory, nerve cell repair, regulation of autophagy, and so forth. But because of the limited oral absorption of puerarin, it affects the protective effect on brain tissue. The nano-encapsulation of Pue can improve its limitation. Therefore, this study investigated the protective effect of Pue drug-loaded PLGA nanoparticles (Pue-PLGA-nps) on brain injury induced by mercuric chloride (HgCl₂) in mice. The mice were divided into normal saline (NS) group, HgCl₂ (4 mg/kg) group, Pue-PLGA-nps (50 mg/kg) group, HgCl₂ + Pue (4 mg/kg + 30 mg/kg) group, and HgCl₂ + Pue-PLGA-nps (4 mg/kg + 50 mg/kg) group. After 28 days of treatment, the mice were observed for behavioral changes, antioxidant capacity, autophagy and inflammatory response, and mercury levels in the brain, blood, and urine were measured. The results showed that HgCl₂ toxicity caused learning and memory dysfunction in mice, increased mercury content in brain and blood, and increased serum levels of interleukin (IL-6), IL-1β, and tumor necrosis factor-α in the mice. HgCl₂ exposure decreased the activity of T-AOC, superoxide dismutase, and glutathione peroxidase, and increased the expression of malondialdehyde in the brain of mice. Moreover, the expression levels of TRIM32, toll-like receptor 4 (TLR4), and LC3 proteins were upregulated. Both Pue and Pue-PLGA-nps interventions mitigated the changes caused by HgCl₂ exposure, and Pue-PLGA-nps further enhanced this effect. Our results suggest that Pue-PLGA-nps can ameliorate HgCl₂-induced brain injury and reduce Hg accumulation, which is associated with inhibition of oxidative stress, inflammatory response, and TLR4/TRIM32/LC3 signaling pathway.     

CX3CL1 induces cell migration and invasion through ICAM-1 expression in oral squamous cell carcinoma cells

Human oral squamous cell carcinoma (OSCC) has been associated with a relatively low survival rate over the years and is characterized by a poor prognosis. C-X3-C motif chemokine ligand 1 (CX3CL1) has been involved in advanced migratory cells. Overexpressed CX3CL1 promotes several cellular responses related to cancer metastasis, including cell movement, migration and invasion in tumour cells. However, CX3CL1 controls the migration ability, and its molecular mechanism in OSCC remains unknown. The present study confirmed that CX3CL1 increased cell movement, migration and invasion. The CX3CL1-induced cell motility is upregulated through intercellular adhesion molecule-1 (ICAM-1) expression in OSCC cells. These effects were significantly suppressed when OSCC cells were pre-treated with CX3CR1 monoclonal antibody (mAb) and small-interfering RNA (siRNA). The CX3CL1-CX3CR1 axis activates promoted PLCβ/PKCα/c-Src phosphorylation. Furthermore, CX3CL1 enhanced activator protein-1 (AP-1) activity. The CX3CR1 mAb and PLCβ, PKCα, c-Src inhibitors reduced CX3CL1-induced c-Jun phosphorylation, c-Jun translocation into the nucleus and c-Jun binding to the ICAM-1 promoter. The present results reveal that CX3CL1 induces the migration of OSCC cells by promoting ICAM-1 expression through the CX3CR1 and the PLCβ/PKCα/c-Src signal pathway, suggesting that CX3CL1-CX3CR1-mediated signalling is correlated with tumour motility and appealed to be a precursor for prognosis in human OSCC.     

海月水母精巢发育及排精过程的观察

采用实验生态学及显微观察的方法研究了海月水母(Aurelia sp.)的精巢发育及其排精过程,并对其精子活力进行了测定。结果表明:在水温20~22℃的条件下,海月水母碟状体经过40 d生长,达到伞径(7.50±0.71)cm、体重(28.70±6.60)g时,精巢出现并生长发育;经过60 d生长,达到伞径(11.77±0.51)cm、体重(83.54±10.36)g时,精巢发育成熟并开始排精;生长90 d后,精巢开始出现退化,当生长110 d时,精巢退化完全。在精巢发育过程中,其宽度和长度分别伴随海月水母伞径的增长而增宽和伸长,并出现折叠现象。海月水母的排精路线为:精子先粘附于精子细丝上,从精巢排出,继而经过胃循环沟、胃口腕沟,最后由口腕基沟排出体外。在水温22℃、盐度30、p H 8.0的条件下,海月水母精子活力随时间延长而降低,其快速运动时间和寿命分别为4 h 30 min和10 h。本研究结果显示,在适宜的环境条件下,海月水母精巢发育迅速,排精路线与过程相对简单,其精子活力强、寿命长,这种高效的生殖策略为其暴发奠定了基础,这或许也是海月水母能在地球上存活年代久远的原因之一。     

Competition and abiotic stress affect the size of mangroves near their geographic range limit

竞争和非生物胁迫影响处于地理分布边界的红树植物的个体大小 关于红树植物竞争的研究大多局限于幼苗和人工林。我们首次对天然红树林中成年红树的种内竞争进行了控制实验研究,旨在检验竞争和非生物因子在决定红树植物个体大小中的相对重要性。研究样 地位于靠近红树林地理分布边界的美国德克萨斯州阿兰萨斯港(Port Aransas)附近区域。该区域的红树林由“灌丛”状的黑红树(萌芽白骨壤,Avicennia germinans)单一物种组成。我们对10个样方中原生红树 林进行疏伐,形成系列红树林覆盖度梯度,在2013–2019年期间观测各样方中红树植物的生长指标,量化分析红树林覆盖度对红树植物生长的影响;并于2019年调查了红树林的冠层高度。研究结果表明,在该研究期间,红树植物的相对生长速率随着红树林覆盖度的增加而降低,100%红树林覆盖度样方中的红 树植物大小几乎没有增长,说明它们已经达到了该红树林密度条件下的最大尺寸。在红树林覆盖度降低 的样方中,株高明显增加,在红树林覆盖度为11%的样方中,红树植物株高增加了约52%。对比临水岸 边和林内两种生境中的样方,处于临水岸边生境的红树林冠层高度比处于林内生境的高约30%,且这两 种生境的红树林冠层高度均随红树林覆盖度的增加而降低。叶片叶绿素含量和冠层光截留量的测定数据 显示,该区域红树植物的生长也受到氮限制的影响。由此表明,处于地理分布边界的“灌丛”状红树林一 方面受到营养的限制,另一方面红树植物种内个体间仍存在较为强烈的竞争,且种内竞争对红树植物生长的影响较该红树林内非生物生境因子更为重要。     

地衣芽孢杆菌耐高温α-淀粉酶基因的克隆、烟草瞬时表达及转化拟南芥的研究

从地衣芽孢杆菌(Bacillus licheniformis)中克隆到耐高温α-淀粉酶基因全长, 构建了原核表达载体, 转入大肠杆菌(Escherichia coli)中, 使用IPTG于28°C诱导6小时后, 通过SDS-PAGE检测到目的蛋白, 分子量约为55 kDa, 并通过酶活力检测实验证明该蛋白具有耐高温α-淀粉酶活性。同时构建了该基因融合GFP的植物表达载体, 通过农杆菌(Agro- bacterium tumefaciens)介导瞬时转化烟草(Nicotiana tabacum)下表皮细胞并在荧光显微镜下观察, 发现在烟草下表皮细胞的细胞质和液泡中均有绿色荧光。使用I₂-KI溶液对乙醇脱色后的烟草叶片进行染色, 显色反应表明在烟草中表达的耐高温α-淀粉酶具有酶活性。最后, 采用农杆菌介导的花蕾浸泡法将重组载体转化到拟南芥(Arabidopsis thaliana)中, 筛选到稳定遗传的耐高温α-淀粉酶基因的拟南芥纯合子。研究结果为后期开展表达耐高温α-淀粉酶的转基因植物的相关研究奠定了实验基础。