HMP

HMP
  • 文章类型: Journal Article
    各种人权学者和行为者对如何解决卢旺达土著和少数群体的脆弱性问题持不同意见。尽管影响这些群体脆弱性的因素受到了越来越多的学术关注,这些研究的结果未能反映身份和歧视的作用。鉴于1994年种族灭绝事件后卢旺达政府试图通过取缔所有种族身份来加强团结与和解,相反,将所有弱势群体混为一谈,历史上被边缘化的人(HMP),一群不同的学者,人权活动家,联合国和非洲联盟的人权文书将这种方法描述为与促进和保护土著和少数群体的权利背道而驰。使用基于人权的方法,本文对身份问题及其如何影响卢旺达少数族裔和土著巴特瓦人享有权利进行了严格的调查。该研究采用了定性研究设计,并通过焦点小组讨论(FGD)和深度访谈(IDI)收集了数据。受访者包括巴特瓦社区的成员,选定的公共机构的官员,非政府组织领导人,以及致力于促进HMP权利的合作社。数据分析涉及数据的转录和编码过程以及最终的反身主题分析。调查结果表明,巴特瓦人社区获得承认和自我认同的权利对社区的不同成员以及公共机构和其他相关行为者的官员具有不同的含义和影响。对现有的研究,该研究证实,围绕巴特瓦人身份的不一致加剧了他们的脆弱性。在政策方面,这项研究表明,在短期内,巴特瓦社区可能需要加强特殊的临时社会保护措施,以便在不损害卢旺达民族团结的情况下改善他们因身份模糊而产生的难题。进一步研究,应该考虑土地的作用,森林和文化进一步边缘化巴特瓦人,以及推理分析的定量方法。
    There have been divergent views by various human rights scholars and actors on how to address the question of vulnerability among indigenous and minority groups in Rwanda. Even though factors influencing vulnerability among these groups have received increasing scholarly attention, findings from these studies fall short of reflecting on the role of identity and discrimination. Whereas the government in Rwanda after the 1994 genocide sought to enhance unity and reconciliation by outlawing all ethnic identities, and instead conflating all vulnerable groups into a nomenclature namely, a Historically Marginalised People (HMP), a divergent group of scholars, human rights activists, the United Nations and African Union\'s instruments of human rights describe this approach as antithetical to the promotion and protection of the rights of indigenous and minority groups. Using the human rights-based approach, this paper critically interrogates the issue of identity and how it has affected the enjoyment of the rights among the minority and indigenous Batwa people in Rwanda. The study employed a qualitative research design with data collected through Focus Group Discussions (FGDs) as well as in-depth interviews (IDIs). Respondents included members of the Batwa community, officials of selected public institutions, leaders in Non-Governmental Organisations (NGOs), and cooperative societies working towards the promotion of rights of the HMP. Data analysis involved the process of transcription and coding of data and the eventual reflexive thematic analysis. The findings show that the rights of the Batwa community to recognition and self-identity have varied meanings and implications to different members of the community as well as officials from public institutions and other relevant actors. To the existing research, the study affirms that the inconsistencies surrounding the Batwa\'s identity have accentuated their vulnerability. In terms of policy, the study suggests that in the short run, the Batwa community may require enhanced special temporary social protection measures in order to ameliorate their conundrum arising from identity ambiguity without compromising Rwanda\'s national unity. Further studies, should consider the role of land, forest and culture in further marginalising the Batwa, as well as quantitative methodology for inferential analysis.
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  • 文章类型: Journal Article
    作为静态冷存储(SCS)的替代方案,先进的灌注技术,例如常温区域灌注(NRP)和非原位灌注(常温或低温)已成为改善DCD肝脏缺血性损伤的一种方法。已经发表了多项研究,这些研究表明,与SCS相比,使用高级灌注时,DCD后的肝移植结果更优越。特别是,这些研究显示晚期灌注的缺血性胆管病变发生率较低.除了改善肝移植后的结果,研究还表明,与SCS相比,使用高级灌注时,DCD供体的肝脏利用率更高。鉴于发生缺血性胆管病变的患者移植物丢失率高,在DCD供体肝脏经历了晚期灌注的显着减少,代表了更广泛利用这些肝脏的关键步骤。有了来自多个试验的令人信服的证据,问这个问题似乎是合理的:先进的灌注应该是DCD肝移植的标准治疗吗?
    As an alternative to static cold storage (SCS), advanced perfusion techniques such as normothermic regional perfusion and ex-situ perfusion (normothermic or hypothermic) have emerged as a way to improve the ischemic injury suffered by donation after circulatory death (DCD) livers. Multiple studies have been published that have demonstrated superior post-DCD liver transplant outcomes when using advanced perfusion compared with SCS. In particular, these studies have shown lower rates of ischemic cholangiopathy with advanced perfusion. In addition to the improved post-liver transplant outcomes, studies have also demonstrated higher rates of liver utilization from DCD donors when advanced perfusion is used compared with SCS. Given the high rates of graft loss in patients who develop ischemic cholangiopathy, the significant reduction seen in DCD donor livers that have undergone advanced perfusion represents a key step in more broad utilization of these livers. With such compelling evidence from multiple trials, it seems reasonable to ask the question: should advanced perfusion be the standard of care for DCD liver transplant?
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  • 文章类型: Journal Article
    抽穗期(或开花时间)是影响水稻品种季节和区域适应的关键农艺性状。未优化的抽穗期不能实现高产率或具有遇到非生物胁迫的高风险。在育种实践中,强烈需要轻度到中度调整抽穗期。基因组编辑是一种有前途的方法,可以更精确,更快地改变水稻的抽穗期。然而,直接敲除调控抽穗期的主要基因并不总能获得预期抽穗期的新种质。定量调整优良品种的抽穗日期仍然具有挑战性,以适应更广泛的地区。在这项研究中,我们使用一种基于CRISPR-Cas9的基因组编辑策略,称为高效多重启动子靶向(HMP),在三个主要抽穗期基因Hd1,Ghd7和DTH8的顺式调控区产生新的等位基因.通过编辑启动子区域并调整这些基因的表达水平,我们获得了一系列具有抽穗期定量变化的种质。我们进行了田间试验,以筛选不同地区的最佳适应线。通过选择具有轻度早抽穗表型的品系,摆脱了冷胁迫并实现了高产潜力,我们成功地将优良品种宁京8(NJ8)扩展到了更高的纬度地区。我们的研究表明,HMP是定量调节水稻抽穗期和将优良品种扩展到更广泛地区的强大工具。
    Heading date (or flowering time) is a key agronomic trait that affects seasonal and regional adaption of rice cultivars. An unoptimized heading date can either not achieve a high yield or has a high risk of encountering abiotic stresses. There is a strong demand on the mild to moderate adjusting the heading date in breeding practice. Genome editing is a promising method which allows more precise and faster changing the heading date of rice. However, direct knock out of major genes involved in regulating heading date will not always achieve a new germplasm with expected heading date. It is still challenging to quantitatively adjust the heading date of elite cultivars with best adaption for broader region. In this study, we used a CRISPR-Cas9 based genome editing strategy called high-efficiency multiplex promoter-targeting (HMP) to generate novel alleles at cis-regulatory regions of three major heading date genes: Hd1, Ghd7 and DTH8. We achieved a series of germplasm with quantitative variations of heading date by editing promoter regions and adjusting the expression levels of these genes. We performed field trials to screen for the best adapted lines for different regions. We successfully expanded an elite cultivar Ningjing8 (NJ8) to a higher latitude region by selecting a line with a mild early heading phenotype that escaped from cold stress and achieved high yield potential. Our study demonstrates that HMP is a powerful tool for quantitatively regulating rice heading date and expanding elite cultivars to broader regions.
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  • 文章类型: Journal Article
    肌腱-骨界面(TBI)整合不良是导致前交叉韧带(ACL)重建后患者愈合质量不佳的主要原因之一。最近发现H型血管通过调节骨-血管生成串扰密切调节骨形成。因此,有利于H型血管形成的策略可能是改善移植物骨整合的有希望的治疗方法。在这项研究中,我们首次报道了狭缝引导配体3(slit3)的治疗结果,一种有利于H型血管形成的新型促血管生成因子,在ACL重建小鼠的TBI愈合中。将小鼠(n=87)分为三组进行各种治疗:水凝胶微粒(HMP,对照组),slit3@HMP,和slit3中和抗体@HMP(slit3-AB@HMP)。组织学分析,步态表现,射线照相测量,并进行生物力学测试以评估TBI愈合质量。与HMP组相比,在Slit3@HMP组中,在TBI处形成了骨向内生长增加和纤维瘢痕组织减少。同时,相对于HMP组,slit3-AB@HMP抑制骨向内生长并增加纤维瘢痕组织的形成。与HMP组相比,slit3@HMP有利于TBI的H型血管形成,而slit3-AB@HMP阻碍了它。根据Micro-CT评估,与HMP组相比,slit3@HMP显着增加了隧道周围的骨量,而slit3-AB@HMP显着减少了隧道周围的骨量。Slit3@HMP组中的小鼠在站立时间方面表现出最佳的步态表现,步幅长度,爪印区域,和立场压力。动态松弛度测量和拉伸测试显示,相对于其他两组,slit3@HMP组表现出显着降低的松弛位移和改善的破坏载荷和刚度。总的来说,注射Slit3可用于增强腱-骨整合,这可能归因于H型血管耦合的血管生成-成骨串扰的调节。
    Poor tendon-bone interface (TBI) integration is one of the major causes contributing to unsatisfactory healing quality in patients after anterior cruciate ligament (ACL) reconstruction. Type H vessels have been recently found to closely modulate bone formation via regulation of the osteo-angiogenic crosstalk, so the strategies favoring type H vessel formation may be promising therapeutic approaches for improved graft osteointegration. In this study, we reported for the first time the treatment outcome of slit guidance ligand 3 (slit3), a novel proangiogenic factor favoring type H vessel formation, in TBI healing in mice with ACL reconstruction. The mice (n = 87) were divided into three groups for various treatments: hydrogel microparticles (HMP, control group), slit3@HMP, and slit3 neutralizing antibody@HMP (slit3-AB@HMP). Histological analysis, gait performance, radiographic measurement, and biomechanical testing were performed to assess the TBI healing quality. Increased bony ingrowth and reduced fibrous scar tissue was formed at the TBI in the slit3@HMP group when compared to the HMP group. Meanwhile, the slit3-AB@HMP inhibited the osseous ingrowth and increased fibrous scar tissue formation relative to the HMP group. Compared to the HMP group, the slit3@HMP favored type H vessel formation at the TBI while the slit3-AB@HMP impeded it. According to micro-CT assessment, compared to the HMP group, the slit3@HMP significantly increased the peri-tunnel bone mass while the slit3-AB@HMP significantly reduced the peri-tunnel bone mass. The mice in the slit3@HMP group showed the best gait performance in terms of stance time, stride length, paw print area, and stance pressure. Dynamic laxity measurement and tensile testing showed the slit3@HMP group exhibited significantly reduced laxity displacement and improved failure load and stiffness relative to the other two groups. Collectively, the injection of slit3 could be used to enhance tendon-bone integration, which may be ascribed to modulation of angiogenesis-osteogenesis crosstalk coupled by type H vessels.
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  • 文章类型: Journal Article
    一氧化氮(·NO)是一种常见的抗微生物剂,已知会破坏氨基酸(AA)生物合成途径中的含铁酶。用大肠杆菌,·NO在有氧环境中被Hmp解毒,这是一种响应·NO从头合成的酶。有了这个知识库,预计在细胞外环境中AAs的可用性将增强·NO解毒,因为AA会促进HMP的翻译。然而,我们观察到,在存在AA(AA)的情况下生长和处理的种群中,与在不存在AA(AA-)的情况下生长和应激的种群相比,大肠杆菌的·NO解毒要慢得多。进一步的实验表明,AA+群体在·NO胁迫下难以翻译蛋白质,并且·NO激活了AA+群体中的严格反应。其他工作显示,在·NO胁迫的AA培养物中,ATP的消耗显着,远远超过了·NO胁迫的AA-种群。转录,翻译,和RelA没有发现是观察到的ATP耗竭的重要贡献者,而AA进口被认为是一个重要的ATP消耗途径。缓解ATP消耗,同时保持获得部分恢复的AA·NO解毒,这表明ATP耗竭导致了在·NO胁迫的AA种群中观察到的翻译困难。这些数据揭示了大肠杆菌的·NO响应网络内的意外相互作用,该相互作用在AA丰富的条件下刺激RelA的严格响应。
    Nitric oxide (·NO) is a prevalent antimicrobial that is known to damage iron-containing enzymes in amino acid (AA) biosynthesis pathways. With Escherichia coli, ·NO is detoxified in aerobic environments by Hmp, which is an enzyme that is synthesized de novo in response to ·NO. With this knowledgebase, it is expected that the availability of AAs in the extracellular environment would enhance ·NO detoxification, because AAs would foster translation of Hmp. However, we observed that ·NO detoxification by E. coli was far slower in populations grown and treated in the presence of AAs (AA+) in comparison to those grown and stressed in the absence of AAs (AA-). Further experiments revealed that AA+ populations had difficulty translating proteins under ·NO stress, and that ·NO activated the stringent response in AA+ populations. Additional work revealed significant ATP depletion in ·NO-stressed AA+ cultures that far exceeded that of ·NO-stressed AA- populations. Transcription, translation, and RelA were not found to be significant contributors to the ATP depletion observed, whereas AA import was implicated as a significant ATP consumption pathway. Alleviating ATP depletion while maintaining access to AAs partially restored ·NO detoxification, which suggested that ATP depletion contributed to the translational difficulties observed in ·NO-stressed AA+ populations. These data reveal an unexpected interaction within the ·NO response network of E. coli that stimulates a stringent response by RelA in conditions where AAs are plentiful.
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  • 文章类型: Journal Article
    重金属相关蛋白(HMPs)参与重金属解毒。尽管已经在几种植物中发现了HMP,迄今为止,尚无研究确定甘蓝型油菜中的HMPs(B.rapa)。这里,我们通过生物信息学方法鉴定了85种潜在的HMPs。鉴定基因的启动子含有许多与应激反应相关的元件,包括对脱落酸的反应,低温,还有茉莉酸甲酯.BrHMP14、BrHMP16、BrHMP32、BrHMP41和BrHMP42在Cu2+下表达上调,Cd2+,Zn2+,和Pb2+应力。BrHMP06、BrHMP30和BrHMP41在干旱处理后也显著上调。在冷胁迫下,BrHMP06和BrHMP11的转录本主要增加。施加盐胁迫后,BrHMP02、BrHMP16和BrHMP78的表达被诱导。我们观察到在花粉-柱头相互作用期间,自交不亲和(SI)反应期间BrHMP36表达增加,而相容授粉(CP)反应中的表达减少。这些表达的变化表明这些基因在HMPs中的功能包括参与重金属运输,排毒,以及对非生物胁迫的反应,具有有性生殖功能的潜力。我们通过蛋白质-蛋白质相互作用(PPI)分析发现了这些关键参与者的潜在共同功能伴侣,并发现已知一些预测的蛋白质伴侣参与相应的应激反应。最后,磷酸化研究揭示了BrHMPs中的许多磷酸化位点,提示翻译后修饰可能发生在BrHMP介导的应激反应过程中。这种综合分析为研究BrHMP基因在B.rapa中的分子机制提供了重要线索,特别是对于非生物胁迫和花粉-柱头相互作用。
    Heavy metal-associated proteins (HMPs) participate in heavy metal detoxification. Although HMPs have been identified in several plants, no studies to date have identified the HMPs in Brassica rapa (B. rapa). Here, we identified 85 potential HMPs in B. rapa by bioinformatic methods. The promoters of the identified genes contain many elements associated with stress responses, including response to abscisic acid, low-temperature, and methyl jasmonate. The expression levels of BrHMP14, BrHMP16, BrHMP32, BrHMP41, and BrHMP42 were upregulated under Cu2+, Cd2+, Zn2+, and Pb2+ stresses. BrHMP06, BrHMP30, and BrHMP41 were also significantly upregulated after drought treatment. The transcripts of BrHMP06 and BrHMP11 increased mostly under cold stress. After applying salt stress, the expression of BrHMP02, BrHMP16, and BrHMP78 was induced. We observed increased BrHMP36 expression during the self-incompatibility (SI) response and decreased expression in the compatible pollination (CP) response during pollen-stigma interactions. These changes in expression suggest functions for these genes in HMPs include participating in heavy metal transport, detoxification, and response to abiotic stresses, with the potential for functions in sexual reproduction. We found potential co-functional partners of these key players by protein-protein interaction (PPI) analysis and found that some of the predicted protein partners are known to be involved in corresponding stress responses. Finally, phosphorylation investigation revealed many phosphorylation sites in BrHMPs, suggesting post-translational modification may occur during the BrHMP-mediated stress response. This comprehensive analysis provides important clues for the study of the molecular mechanisms of BrHMP genes in B. rapa, especially for abiotic stress and pollen-stigma interactions.
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  • 文章类型: Journal Article
    2-羟基丁酸(2HB)是多种疾病的重要调控因子。在多种疾病中,血清中2HB的循环水平明显升高,例如癌症和2型糖尿病(T2D)。然而,目前没有关于2HB产生细菌的系统研究表明肠道细菌是否有助于循环2HB池。为了解决这个问题,我们使用BLASTP来揭示人类微生物组中产生2HB的细菌的分类学特征,主要分布在变形杆菌门和硬菌门中。体外实验表明,大多数肠道细菌(21/32)至少有一条途径产生2HB,其中包括天冬氨酸,蛋氨酸,苏氨酸,和2-氨基丁酸.特别是,具核梭杆菌合成2HB的能力最强,这足以改变小鼠的结肠2HB浓度。然而,在本研究的时间过程中,抗生素(ABX)和核梭杆菌管饲法均未显着影响小鼠血清2HB水平。一起来看,我们的研究提供了产生2HB的细菌的概况,并表明肠道微生物群是肠腔中2HB浓度的主要贡献者,但对血清2HB浓度的贡献相对较小。
    2-hydroxybutyric acid (2HB) serves as an important regulatory factor in a variety of diseases. The circulating level of 2HB in serum is significantly higher in multiple diseases, such as cancer and type 2 diabetes (T2D). However, there is currently no systematic study on 2HB-producing bacteria that demonstrates whether gut bacteria contribute to the circulating 2HB pool. To address this question, we used BLASTP to reveal the taxonomic profiling of 2HB-producing bacteria in the human microbiome, which are mainly distributed in the phylum Proteobacteria and Firmicutes. In vitro experiments showed that most gut bacteria (21/32) have at least one path to produce 2HB, which includes Aspartic acid, methionine, threonine, and 2-aminobutyric acid. Particularly, Fusobacterium nucleatum has the strongest ability to synthesize 2HB, which is sufficient to alter colon 2HB concentration in mice. Nevertheless, neither antibiotic (ABX) nor Fusobacterium nucleatum gavage significantly affected mouse serum 2HB levels during the time course of this study. Taken together, our study presents the profiles of 2HB-producing bacteria and demonstrates that gut microbiota was a major contributor to 2HB concentration in the intestinal lumen but a relatively minor contributor to serum 2HB concentration.
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  • 文章类型: Journal Article
    虽然在美国,机器灌注技术在临床实践中的采用比欧洲慢得多,FDA批准后,移植景观以及设备可用性的最新变化为快速增长铺平了道路。机器灌注可以提供一种机制来最大化潜在供体肝移植物的利用。的确,多项研究表明,随着技术的实施,器官利用率增加,例如非原位常温机器灌注(NMP),异位低温机器灌注(HMP)和原位常温区域灌注(NRP)。当前的评论描述了美国机器灌注利用的历史和发展以及未来的方向。它还描述了欧洲和美国之间的景观差异,以及这如何影响这些技术的临床应用。
    While adoption of machine perfusion technologies into clinical practice in the United States has been much slower than in Europe, recent changes in the transplant landscape as well as device availability following FDA approval have paved the way for rapid growth. Machine perfusion may provide one mechanism to maximize the utilization of potential donor liver grafts. Indeed, multiple studies have shown increased organ utilization with the implementation of technologies such as ex-situ normothermic machine perfusion (NMP), ex-situ hypothermic machine perfusion (HMP) and in-situ normothermic regional perfusion (NRP). The current review describes the history and development of machine perfusion utilization in the Unites States along with future directions. It also describes the differences in landscape between Europe and the United States and how this has shaped clinical application of these technologies.
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  • 文章类型: Journal Article
    为了提高氟化产品的防龋效果,补充这些产品被认为是控制龋齿的有希望的替代方法。这项研究评估了六偏磷酸钠(HMP)和/或氟化物(F)对变形链球菌和白色念珠菌双物种生物膜的无机成分和pH的影响。生物膜在开始形成后72、78和96小时用含有或不含F的0.25、0.5或1%HMP的溶液处理(500ppm,如氟化钠)。使用含F的溶液(500ppm和1100ppm)和人工唾液作为对照。在第三次处理后,将生物膜暴露于20%蔗糖溶液。随着生物膜的pH值,F的浓度,钙,磷(P),确定了HMP。HMP,结合F,与500ppmF的溶液相比,生物膜流体中的F水平增加,P水平降低。暴露于蔗糖会降低生物质中所有离子的浓度,HMP除外;1%HMP,结合F,促进pH最高。可以得出结论,HMP影响生物膜的无机组成并对生物膜的pH具有缓冲作用。
    In order to improve the anticaries effects of fluoridated products, the supplementation of these products has been considered a promising alternative for caries control. This study evaluated the effects of sodium hexametaphosphate (HMP) and/or fluoride (F) on the inorganic components and pH of Streptococcus mutans and Candida albicans dual-species biofilms. The biofilms were treated 72, 78, and 96 h after the beginning of their formation with 0.25, 0.5, or 1% HMP-containing solutions with or without F (500 ppm, as sodium fluoride). F-containing solutions (500 ppm and 1100 ppm) and artificial saliva were used as controls. The biofilms were exposed to a 20% sucrose solution after the third treatment. Along with the biofilm pH, the concentrations of F, calcium, phosphorus (P), and HMP were determined. HMP, combined with F, increased F levels and decreased P levels in the biofilm fluid compared to that of the solution with 500 ppm F. Exposure to sucrose decreased the concentrations of all ions in the biomass, except for HMP; 1% HMP, combined with F, promoted the highest pH. It can be concluded that HMP affected the inorganic composition of the biofilm and exerted a buffering effect on the biofilm pH.
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  • 文章类型: Journal Article
    微生物群落在自然界中占据不同的生态位,社区成员经常在彼此之间交换各种营养素。虽然大规模的宏基因组和代谢组学研究为这些交流提供了一些启示,单个物种的贡献和特定相互作用的分子细节很难追踪。在这项研究中,我们跟踪维生素B1(硫胺素)及其中间体在大肠杆菌和弧菌的合成共培养物中的微生物之间的交换。硫胺素包含两个部分,4-氨基-5-羟甲基-2-甲基嘧啶(HMP)和4-甲基-5-(2-羟乙基)噻唑(THZ),使用酶ThiC和ThiG通过不同的途径合成,分别,然后与ThiE偶联形成硫胺素。即使大肠杆菌ΔthiC,ΔthiE,ΔthiG突变体是硫胺素营养缺陷型,我们观察到ΔthiC-ΔthiE和ΔthiC-ΔthiG突变体的共培养物能够在硫胺素缺乏的培养基中生长,而ΔthiE-ΔthiG共培养则没有。Further,硫胺素及其中间体在V.anguillarum共培养物以及V.anguillarum和E.coli的混合共培养物中的交换表明,这些微生物之间存在硫胺素代谢和交换的特定模式。我们的研究结果表明,HMP比THz共享更频繁,与以前的观察结果一样,游离HMP和HMP营养缺陷型普遍存在于各种环境中。此外,我们观察到,培养基中外源硫胺素的可用性影响这些菌株是否相互作用或独立生长。这些发现共同强调了必需代谢物交换作为建立和调节合成或天然微生物群落的决定性因素的重要性。重要性维生素B1(硫胺素)是细胞代谢的必需营养素。不能完全或部分合成硫胺素的微生物从其环境中或通过与其群落中的其他微生物成员交换而获得硫胺素。在这项研究中,我们创建了合成的微生物共培养物,它们依赖于共享硫胺素及其生物合成中间体,并观察到其中一些被优先交换。我们还观察到,共培养物组成由硫胺素及其中间体的生产和/或可用性决定。我们对合成共培养物的研究为了解硫胺素在微生物之间的共享提供了分子基础,并为通过交换必需代谢物作为基础来建立合成微生物共培养物奠定了广泛的指导原则。
    Microbial communities occupy diverse niches in nature, and community members routinely exchange a variety of nutrients among themselves. While large-scale metagenomic and metabolomic studies shed some light on these exchanges, the contribution of individual species and the molecular details of specific interactions are difficult to track. In this study, we follow the exchange of vitamin B1 (thiamin) and its intermediates between microbes within synthetic cocultures of Escherichia coli and Vibrio anguillarum. Thiamin contains two moieties, 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) and 4-methyl-5-(2-hydroxyethyl)thiazole (THZ), which are synthesized by distinct pathways using enzymes ThiC and ThiG, respectively, and then coupled by ThiE to form thiamin. Even though E. coli ΔthiC, ΔthiE, and ΔthiG mutants are thiamin auxotrophs, we observed that cocultures of ΔthiC-ΔthiE and ΔthiC-ΔthiG mutants are able to grow in a thiamin-deficient medium, whereas the ΔthiE-ΔthiG coculture does not. Further, the exchange of thiamin and its intermediates in V. anguillarum cocultures and in mixed cocultures of V. anguillarum and E. coli revealed that there exist specific patterns for thiamin metabolism and exchange among these microbes. Our findings show that HMP is shared more frequently than THZ, concurrent with previous observations that free HMP and HMP auxotrophy is commonly found in various environments. Furthermore, we observe that the availability of exogenous thiamin in the media affects whether these strains interact with each other or grow independently. These findings collectively underscore the importance of the exchange of essential metabolites as a defining factor in building and modulating synthetic or natural microbial communities. IMPORTANCE Vitamin B1 (thiamin) is an essential nutrient for cellular metabolism. Microorganisms that are unable to synthesize thiamin either fully or in part exogenously obtain it from their environment or via exchanges with other microbial members in their community. In this study, we created synthetic microbial cocultures that rely on sharing thiamin and its biosynthesis intermediates and observed that some of them are preferentially exchanged. We also observed that the coculture composition is dictated by the production and/or availability of thiamin and its intermediates. Our studies with synthetic cocultures provide the molecular basis for understanding thiamin sharing among microorganisms and lay out broad guidelines for setting up synthetic microbial cocultures by using the exchange of an essential metabolite as their foundation.
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