降血脂药物（DEHP）对酰基CoA氧化酶基因反式作用因子的影响

从对照和用ＤＥＨＰ处理的大鼠肝脏提取核蛋白,以含酰基ＣｏＡ氧化酶（ＡＯＸ）基因表达调控部位的ＤＮＡ片段和该基因的不同蛋白结合位点的ＤＮＡ片段作为核蛋白结合反应的探针,通过凝胶电泳迁移率改变实验和Ｓｏｕｔｈｗｅｓｔｅｒｎ印迹分析检查了ＤＥＨＰ对ＡＯＸ基因反式作用因子的影响。结果表明,降血脂药物ＤＥＨＰ可显著增加ＡＯＸ基因反式作用因子的含量和（或）与基因的结合活性,在转录水平上促进基因的表达。     

枯草杆菌BS224菌在防治Ⅲ°烧伤创面感染中痂下组织细菌数量的动态观察

对48例Ⅲ°烧伤病人的创面,定量植入枯草杆菌BS224菌后,分别在24h、48h、72h及96h做痂下组织细菌定量检测。结果显示:枯草杆菌对痂下组织的致病菌有明显的拮抗作用。感染创面的BS224菌体数量24—48小时显著增加,72—96小时而下降。与清洁创面的BS224菌动态变化上相同,呈常态曲线的规律变化。     

Phytopathogenic bacteria utilize host glucose as a signal to stimulate virulence through LuxR homologues

Chemical signal-mediated biological communication is common within bacteria and between bacteria and their hosts. Many plant-associated bacteria respond to unknown plant compounds to regulate bacterial gene expression. However, the nature of the plant compounds that mediate such interkingdom communication and the underlying mechanisms remain poorly characterized. Xanthomonas campestris pv. campestris (Xcc) causes black rot disease on brassica vegetables. Xcc contains an orphan LuxR regulator (XccR) which senses a plant signal that was validated to be glucose by HPLC-MS. The glucose concentration increases in apoplast fluid after Xcc infection, which is caused by the enhanced activity of plant sugar transporters translocating sugar and cell-wall invertases releasing glucose from sucrose. XccR recruits glucose, but not fructose, sucrose, glucose 6-phosphate, and UDP-glucose, to activate pip expression. Deletion of the bacterial glucose transporter gene sglT impaired pathogen virulence and pip expression. Structural prediction showed that the N-terminal domain of XccR forms an alternative pocket neighbouring the AHL-binding pocket for glucose docking. Substitution of three residues affecting structural stability abolished the ability of XccR to bind to the luxXc box in the pip promoter. Several other XccR homologues from plant-associated bacteria can also form stable complexes with glucose, indicating that glucose may function as a common signal molecule for pathogen–plant interactions. The conservation of a glucose/XccR/pip-like system in plant-associated bacteria suggests that some phytopathogens have evolved the ability to utilize host compounds as virulence signals, indicating that LuxRs mediate an interkingdom signalling circuit.     

生长抑素受体2的小鼠时空组织表达谱

生长抑素(somatostatin, SST)作为一种抑制性多肽激素,在多种生物过程中发挥重要的功能。生长抑素受体2 (somatostatin receptor 2, SSTR2)作为生长抑素表达最广泛的受体在多种组织中表达,但其表达的具体细胞类型尚不清楚。本研究在小鼠不同发育阶段的多种组织中鉴定了SSTR2蛋白表达的细胞类型。通过多色免疫荧光在小鼠胚胎期15.5 d、出生后1 d、7 d、15 d、3个月和6个月的脑、骨、肺、肠道、皮肤、胃、脾和肾等组织中检测了Sstr2基因的表达。结果发现Sstr2在不同发育阶段的多种组织的特定细胞类型中表达,包括脑神经元和星形胶质细胞,骨的间充质基质细胞、造血细胞和B细胞,肺的巨噬细胞、Ⅱ型肺泡上皮细胞和气道纤毛细胞,肠道的上皮细胞和神经元,皮肤的毛囊细胞,胃体的上皮细胞,脾的造血干细胞、造血祖细胞和神经纤维,肾的肾小管上皮细胞等。本研究确定了小鼠多组织不同发育阶段Sstr2表达的细胞类型,为生长抑素与生长抑素受体2的生理功能研究提供了新的线索。     

Inhibition of the HIV-1 and HIV-2 proteases by curcumin and curcumin boron complexes

Curcumin, a relatively non-toxic natural product isolated from Curcuma longa, is a modest inhibitor of the HIV-1 (1050 = 100 μM) and HIV-2 (IC₅₀ = 250 μM) proteases. Simple modifications of the curcumin structure raise the IC₅₀ value but complexes of the central dihydroxy groups of curcumin with boron lower the IC₅₀ to a value as low as 6 μM. The boron complexes are also time-dependent inactivators of the HIV proteases. The increased affinity of the boron complexes may reflect binding of the orthogonal domains of the inhibitor in intersecting sites within the substrate-binding cavity of the enzyme, while activation of the ,β-unsaturated carbonyl group of curcumin by chelation to boron probably accounts for time-dependent inhibition of the enzyme.     

LEP and LEPR are possibly a double-edged sword for wound healing

Wound healing is a complex and error-prone process. Wound healing in adults often leads to the formation of scars, a type of fibrotic tissue that lacks skin appendages. Hypertrophic scars and keloids can also form when the wound-healing process goes wrong. Leptin (Lep) and leptin receptors (LepRs) have recently been shown to affect multiple stages of wound healing. This effect, however, is paradoxical for scarless wound healing. On the one hand, Lep exerts pro-inflammatory and profibrotic effects; on the other hand, Lep can regulate hair follicle growth. This paper summarises the role of Lep and LepRs on cells in different stages of wound healing, briefly introduces the process of wound healing and Lep and LepRs, and examines the possibility of promoting scarless wound healing through spatiotemporal, systemic, and local regulation of Lep levels and the binding of Lep and LepRs.     

Thermostability enhancement of polyethylene terephthalate degrading PETase using self- and nonself-ligating protein scaffolding approaches

Polyethylene terephthalate (PET) hydrolase enzymes show promise for enzymatic PET degradation and green recycling of single-use PET vessels representing a major source of global pollution. Their full potential can be unlocked with enzyme engineering to render activities on recalcitrant PET substrates commensurate with cost-effective recycling at scale. Thermostability is a highly desirable property in industrial enzymes, often imparting increased robustness and significantly reducing quantities required. To date, most engineered PET hydrolases show improved thermostability over their parental enzymes. Here, we report engineered thermostable variants of Ideonella sakaiensis PET hydrolase enzyme (IsPETase) developed using two scaffolding strategies. The first employed SpyCatcher-SpyTag technology to covalently cyclize IsPETase, resulting in increased thermostability that was concomitant with reduced turnover of PET substrates compared to native IsPETase. The second approach using a GFP-nanobody fusion protein (vGFP) as a scaffold yielded a construct with a melting temperature of 80°C. This was further increased to 85°C when a thermostable PETase variant (FAST PETase) was scaffolded into vGFP, the highest reported so far for an engineered PET hydrolase derived from IsPETase. Thermostability enhancement using the vGFP scaffold did not compromise activity on PET compared to IsPETase. These contrasting results highlight potential topological and dynamic constraints imposed by scaffold choice as determinants of enzyme activity.     

Subcellular Distribution and Chemical Forms of Cadmium in the Medicine Food Homology Plant <i>Platycodon grandiflorum</i> (Jacq.) A.DC.

Although Platycodon grandiflorum (Jacq.) A.DC. is a renowned medicine food homology plant, reports of excessive cadmium (Cd) levels are common, which affects its safety for clinical use and food consumption. To enable its Cd levels to be regulated or reduced, it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant, in addition to its detoxification mechanisms. This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P. grandiflorum. The experimental results showed that Cd was mainly accumulated in the roots [predominantly in the cell wall (50.96%–61.42%)], and it was found primarily in hypomobile and hypotoxic forms. The proportion of Cd in the soluble fraction increased after Cd exposure, and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves, with a higher increase in oxalate Cd. Therefore, it is likely that root retention mechanisms, cell wall deposition, vacuole sequestration, and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P. grandiflorum. The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P. grandiflorum, and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.     

中国沙棘幼苗对土壤镉生理耐性和富集转运特征的性别差异

为探究中国沙棘对土壤镉(Cd)胁迫的性别响应差异,该研究以中国沙棘2年生幼苗为材料,利用盆栽试验研究在不同浓度Cd处理下(0(CK)、25、50、100和200 mg·kg^-1)雌、雄株幼苗的生长、叶片生理特性以及Cd富集特征的差异。结果表明：(1)Cd处理下中国沙棘幼苗雌、雄株的株高和基径生长以及各器官生物量均表现出低浓度(<50 mg·kg^-1)促进,高浓度(> 100 mg·kg^-1)抑制的现象;低浓度Cd处理下雌株的株高、基径增长率和生物量的增幅均高于雄株;高浓度Cd处理下(200 mg·kg^-1)雄株株高增长率、叶生物量和总生物量分别较CK显著降低,而雌株均未显著下降。(2)随着Cd浓度升高,雌、雄株叶片光合色素含量和抗氧化酶活性呈先升后降的变化趋势,丙二醛(MDA)和渗透调节物质含量呈上升趋势;Cd浓度为50～200 mg·kg^-1时,雌株叶片的光合色素含量、抗氧化酶活性和渗透调节物质含量均高于雄株,而MDA含量始终低于雄株。(3)随着Cd浓度升高,雌、...