BLAST

成釉细胞瘤
  • 文章类型: Journal Article
    背景:创伤可导致全身炎症,从而导致器官功能障碍,但是对大脑的影响,特别是在颅外侮辱之后,在很大程度上被忽视了。
    方法:在我们先前发现的基础上,我们旨在了解全身炎症对暴露于(1)爆炸超压暴露[BOP]的大鼠八个脑区神经炎症基因转录本的影响,(2)皮肤热损伤[BU],(3)复杂的四肢损伤,止血带引起的缺血3小时(h),和后肢截肢[CEI+tI+HLA],(4)损伤后(hpi)6、24和168小时的BOP+BU或(5)BOP+CEI和延迟HLA[BOP+CEI+dHLA]。
    结果:全球,差异表达基因(DEGs)的数量和大小与损伤严重程度相关,全身性炎症标志物,和终末器官损伤,由几种趋化因子/细胞因子(Csf3,Cxcr2,Il16和Tgfb2)驱动,神经类固醇/前列腺素(Cyp19a1,Ptger2和Ptger3),和神经变性的标志物(Gfap,Grin2b,和Homer1)。BOP后,区域性神经炎症活动受到的影响最小。非爆炸伤(在BU和CEI+tI+HLA组中)促成了较早的,大脑区域的强烈和多样化的神经炎症反应(比BOP组高2-50倍),而合并创伤(BOPCEIdHLA组)在除小脑以外的所有区域均显着进展了神经炎症。相比之下,与BU相比,BOPBU导致几种关键的神经炎-神经退行性标志物的活性差异。DEG的t-SNE图表明,范围,炎症反应的持续时间取决于大脑区域。不管损伤类型,丘脑和下丘脑,这对维持体内平衡至关重要,有最多的DEG。我们的结果表明,在研究期间,所有组的神经炎症逐渐增加或保持在峰值水平。而终末器官功能障碍的标志物减少或以其他方式解决。
    结论:总的来说,这些发现强调了大脑对全身炎症介质的敏感性,并提供了免疫-大脑串扰的一个例子。有必要进行后续分子和行为调查,以了解大脑的短期至长期病理生理后果。特别是血脑屏障破坏的机制,免疫细胞渗透激活,和小胶质细胞激活。
    BACKGROUND: Trauma can result in systemic inflammation that leads to organ dysfunction, but the impact on the brain, particularly following extracranial insults, has been largely overlooked.
    METHODS: Building upon our prior findings, we aimed to understand the impact of systemic inflammation on neuroinflammatory gene transcripts in eight brain regions in rats exposed to (1) blast overpressure exposure [BOP], (2) cutaneous thermal injury [BU], (3) complex extremity injury, 3 hours (h) of tourniquet-induced ischemia, and hind limb amputation [CEI+tI+HLA], (4) BOP+BU or (5) BOP+CEI and delayed HLA [BOP+CEI+dHLA] at 6, 24, and 168 h post-injury (hpi).
    RESULTS: Globally, the number and magnitude of differentially expressed genes (DEGs) correlated with injury severity, systemic inflammation markers, and end-organ damage, driven by several chemokines/cytokines (Csf3, Cxcr2, Il16, and Tgfb2), neurosteroids/prostaglandins (Cyp19a1, Ptger2, and Ptger3), and markers of neurodegeneration (Gfap, Grin2b, and Homer1). Regional neuroinflammatory activity was least impacted following BOP. Non-blast trauma (in the BU and CEI+tI+HLA groups) contributed to an earlier, robust and diverse neuroinflammatory response across brain regions (up to 2-50-fold greater than that in the BOP group), while combined trauma (in the BOP+CEI+dHLA group) significantly advanced neuroinflammation in all regions except for the cerebellum. In contrast, BOP+BU resulted in differential activity of several critical neuroinflammatory-neurodegenerative markers compared to BU. t-SNE plots of DEGs demonstrated that the onset, extent, and duration of the inflammatory response are brain region dependent. Regardless of injury type, the thalamus and hypothalamus, which are critical for maintaining homeostasis, had the most DEGs. Our results indicate that neuroinflammation in all groups progressively increased or remained at peak levels over the study duration, while markers of end-organ dysfunction decreased or otherwise resolved.
    CONCLUSIONS: Collectively, these findings emphasize the brain\'s sensitivity to mediators of systemic inflammation and provide an example of immune-brain crosstalk. Follow-on molecular and behavioral investigations are warranted to understand the short- to long-term pathophysiological consequences on the brain, particularly the mechanism of blood-brain barrier breakdown, immune cell penetration-activation, and microglial activation.
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  • 文章类型: Journal Article
    细菌性叶枯病(米黄单胞菌pv。稻米)和稻瘟病(稻瘟病)是世界水稻种植区周围的主要生物胁迫。通过标记辅助回交育种开发抗性品种是实现稳定产量的最经济,生态友好的方法。在公认的抗性基因中,Xa21和Pi54对世界各地的许多Xoo和blast菌株具有广谱抗性。在本研究中,我们已经有效地将细菌枯萎病抗性基因(Xa21)和细菌抗性基因(Pi54)渗入RP-Bio-Patho-2的易感品种ADT43中,并进行了农艺表型选择,通过MABC研究烹饪品质和谷物性状。MABC一直持续到BC2F2代,具有Xa21的特异性标记pTA248和Pi54抗性基因的Pi54MAS。在每次回交中,使用一组亲本多态性的SSR标记来最大程度地恢复轮回亲本基因组。将来自BC2F1的“阳性植物”自交以产生BC2F2,并鉴定了细菌性叶枯病和抗稻瘟病基因的纯合品系以进行进一步评估。
    Bacterial Leaf Blight (Xanthomonas oryzae pv. oryzae) and blast (Magnaporthe oryzae) are the major biotic stresses around the rice-growing zones of the world. The development of resistant varieties through Marker Assisted Backcross Breeding is the utmost economical and eco-friendly method for achieving stable yield. Amongst the resistance genes recognized, Xa21 and Pi54 possess broad-spectrum resistance to many Xoo and blast strains around the world. In the present study, we have effectively introgressed a Bacterial Blight resistance gene (Xa21) and a blast resistance gene (Pi54) into susceptible variety ADT43 from RP-Bio-Patho-2 coupled with phenotypic selection for agronomic, cooking quality and grain traits through MABC. MABC was sustained till BC2F2 generation with specific markers pTA248 for Xa21 and Pi54MAS for Pi54 resistance genes. A set of SSR markers for parental polymorphism were utilized for maximum regaining of recurrent parent genome in each backcrossing. \"Positive plants\" from BC2F1 were selfed to generate BC2F2 and the homozygous lines for bacterial leaf blight and blast resistance genes were identified for further assessment.
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  • 文章类型: Journal Article
    背景:与基于形态学的鉴定相比,通过使用线粒体cox1基因鉴定未知物种的分子方法是有效且可靠的。水牛水蛭被称为亚洲水牛水蛭,在南亚发现,由于其药用特性,传统上用作药物。
    结果:该研究旨在使用cox1基因测序及其系统发育关系来分离和鉴定水蛭物种。分析了细胞色素c氧化酶亚基I(cox1)线粒体基因的核苷酸序列,以进行物种鉴定和关键的治疗性水蛭的系统发育关系。用cox1基因特异性引物扩增从水蛭样品分离的DNA。与H.manillensis序列的BLAST结果与H.manillensis的同源性为89.24%,系统发育树分析揭示了与其他GenBank提交序列的遗传关系。
    结论:本研究得出结论,cox1基因可能是鉴定水蛭H.manillensis的有效方法,并提供了足够的系统发育信息来区分H.manillensis,表明基于mtDNA的重要方法进行物种鉴定。
    BACKGROUND: A molecular approach for the identification of unknown species by the using mitochondrial cox1 gene is an effective and reliable as compared with morphological-based identification. Hirudinaria manillensis referred to as Asian Buffalo Leech, is found in South Asia and traditionally used as medicine owing to its medicinal properties.
    RESULTS: The study aimed to isolate and identify the leech species using cox1 gene sequencing and their phylogenetic relationships. The nucleotide sequences of cytochrome c oxidase subunit I (cox1) mitochondrial genes were analyzed for species identification and the phylogenetic relationship of crucial therapeutic leech Hirudinaria manillensis. The isolated DNA from the leech sample was amplified with cox1 gene-specific primers. BLAST results with the H. manillensis sequence showed 89.24% homology with H. manillensis and phylogenetic tree analysis revealed the genetic relationship with other GenBank submitted sequences.
    CONCLUSIONS: The present study concluded that the cox1 gene could be an effective way to identify the leech H. manillensis and provided sufficient phylogenetic information to distinguish H. manillensis indicating a significant mtDNA-based approach to species identification.
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  • 文章类型: Journal Article
    大米,全球范围内的关键主食,由于非生物和生物应激源的流行率上升,在产量保存方面面临不断升级的挑战,近年来频繁的气候波动加剧了。此外,中国南方水稻种植区普遍的炎热气候给优质水稻的种植带来了障碍,重粮品种。解决这一困境需要开发能够承受多种压力因素的弹性品种。为了实现这一目标,我们的研究采用了广谱防爆线Digu,褐飞虱(BPH)抗性系ASD7,重粒骨干恢复系Fuhui838(FH838)和Shuhui527(SH527)作为亲本材料进行杂交和多次杂交。分子标记的掺入促进了六个靶基因的快速金字塔化(Pi5,Pita,Pid2、Pid3、Bph2和Wxb)。通过包括抗爆性的综合评价,耐BPH,耐寒性,颗粒外观,和质量,除了农艺性状选择,一条有前途的修复线,贵汇5501(GH5501),开发成功。它展示了对爆炸的广谱抗性,对75个人工接种的分离株表现出77.33%的抗性频率,对BPH的中等抗性(3.78级),幼苗期(1.80级)耐寒性强,和具有良好谷物品质的重谷物(1,000粒重,达到35.64g)的特征。稻米的主要品质参数为GH5501,除碱铺展值外,达到或超过优质食用水稻品种的二级国家标准,标志着南方水稻种植区优质重粒品种生产的显著进步。利用GH5501,一种名为Nayou5501的混合组合,具有高产率,质量很好,和对多种应力的抵抗力,2021年在广西选育并获得水稻品种批准。此外,基因芯片的基因组分析显示,GH5501拥有额外的20个特殊等位基因,如NRT1.1B高效利用氮,SKC1耐盐性,和STV11对水稻条纹病毒的抗性。因此,恢复系GH5501可以作为后续高产育种的宝贵资源,质量很好,和耐逆性杂交水稻品种。
    Rice, a critical staple on a global scale, faces escalating challenges in yield preservation due to the rising prevalence of abiotic and biotic stressors, exacerbated by frequent climatic fluctuations in recent years. Moreover, the scorching climate prevalent in the rice-growing regions of South China poses obstacles to the cultivation of good-quality, heavy-grain varieties. Addressing this dilemma requires the development of resilient varieties capable of withstanding multiple stress factors. To achieve this objective, our study employed the broad-spectrum blast-resistant line Digu, the brown planthopper (BPH)-resistant line ASD7, and the heavy-grain backbone restorer lines Fuhui838 (FH838) and Shuhui527 (SH527) as parental materials for hybridization and multiple crossings. The incorporation of molecular markers facilitated the rapid pyramiding of six target genes (Pi5, Pita, Pid2, Pid3, Bph2, and Wxb ). Through a comprehensive evaluation encompassing blast resistance, BPH resistance, cold tolerance, grain appearance, and quality, alongside agronomic trait selection, a promising restorer line, Guihui5501 (GH5501), was successfully developed. It demonstrated broad-spectrum resistance to blast, exhibiting a resistance frequency of 77.33% against 75 artificially inoculated isolates, moderate resistance to BPH (3.78 grade), strong cold tolerance during the seedling stage (1.80 grade), and characteristics of heavy grains (1,000-grain weight reaching 35.64 g) with good grain quality. The primary rice quality parameters for GH5501, with the exception of alkali spreading value, either met or exceeded the second-grade national standard for premium edible rice varieties, signifying a significant advancement in the production of good-quality heavy-grain varieties in the southern rice-growing regions. Utilizing GH5501, a hybrid combination named Nayou5501, characterized by high yield, good quality, and resistance to multiple stresses, was bred and received approval as a rice variety in Guangxi in 2021. Furthermore, genomic analysis with gene chips revealed that GH5501 possessed an additional 20 exceptional alleles, such as NRT1.1B for efficient nitrogen utilization, SKC1 for salt tolerance, and STV11 for resistance to rice stripe virus. Consequently, the restorer line GH5501 could serve as a valuable resource for the subsequent breeding of high-yielding, good-quality, and stress-tolerant hybrid rice varieties.
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  • 文章类型: Journal Article
    背景:精确评估真菌分生孢子的产生可能有助于研究抗性机制和植物抗病性。在这项研究中,高光谱成像(HSI)用于量化在受控条件下生长的水稻品种叶片上稻瘟病菌的孢子形成。三种水稻基因型(CO39,Nipponbare,IR64)接种了米曲霉分离株Guy11和Li1497。光谱信息(450-850nm,在诱导病原体孢子形成之前和之后记录了140个波段)的典型叶片胚症状。
    结果:M.稻米在高度易感基因型上比在中度易感基因型上产生更多的分生孢子,而抗性基因型导致没有孢子形成。基因型CO39在诱导孢子形成前后记录的反射光谱变化明显高于Nipponbare。用于监督分类的光谱角度映射器算法允许对爆炸症状子区域进行分类,并通过米曲霉孢子形成对病变区域进行量化。差异光谱下面积之间的相关性(即没有和有孢子形成的光谱差异),每个病灶的分生孢子数和每个病灶面积的分生孢子数均为阳性,并且可以在光谱数据中再现基于计数的水稻-米曲霉相互作用差异。
    结论:HSI提供了一种精确和客观的方法来评估受感染水稻植株的米曲霉分生孢子产量,揭示了视觉上无法检测到的差异。
    BACKGROUND: Precise evaluation of fungal conidia production may facilitate studies on resistance mechanisms and plant breeding for disease resistance. In this study, hyperspectral imaging (HSI) was used to quantify the sporulation of Magnaporthe oryzae on the leaves of rice cultivars grown under controlled conditions. Three rice genotypes (CO 39, Nipponbare, IR64) differing in susceptibility to blast were inoculated with M. oryzae isolates Guy 11 and Li1497. Spectral information (450-850 nm, 140 wavebands) of typical leaf blast symptoms was recorded before and after induction of sporulation of the pathogen.
    RESULTS: M. oryzae produced more conidia on the highly susceptible genotype than on the moderately susceptible genotype, whereas the resistant genotype resulted in no sporulation. Changes in reflectance spectra recorded before and after induction of sporulation were significantly higher in genotype CO 39 than in Nipponbare. The spectral angle mapper algorithm for supervised classification allowed for the classification of blast symptom subareas and the quantification of lesion areas with M. oryzae sporulation. The correlation between the area under the difference spectrum (viz. spectral difference without and with sporulation) and the number of conidia per lesion and the number of conidia per lesion area was positive and count-based differences in rice - M. oryzae interaction could be reproduced in the spectral data.
    CONCLUSIONS: HSI provided a precise and objective method of assessing M. oryzae conidia production on infected rice plants, revealing differences that could not be detected visually.
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  • 文章类型: Journal Article
    病毒基因组研究领域经历了前所未有的数据量增长。已知病毒的新毒株不断被添加到GenBank数据库中,因此是与我们的序列数据库几乎没有相似之处的全新物种。除此之外,宏基因组技术有可能进一步增加测序基因组的数量和速率。此外,重要的是要考虑到病毒具有一系列独特的特征,这些特征通常会破坏分子生物学的教条,例如,逆转录病毒中从RNA到DNA的信息流动以及RNA分子作为基因组的使用。因此,从病毒基因组中提取有意义的信息仍然是一个挑战,比较未知和我们的特征序列数据库的标准方法可能需要调整。因此,已经创建了几种生物信息学方法和工具来应对分析病毒数据的挑战。本章提供了一些用于病毒比较分析的最重要的生物信息学技术的描述和方案。作者还提供了关于病毒的独特功能如何影响标准分析以及如何克服一些主要问题来源的评论和讨论。协议和主题强调在线工具(用户更容易访问),并提供大多数生物信息学家在日常工作中使用命令行管道所做的真实体验。讨论的主题包括(1)聚类相关基因组,(2)小RNA病毒的全基因组多序列比对,(3)标记基因和物种隶属度的蛋白质比对,(4)变体调用和注释,(5)病毒学分析和病原鉴定。
    The field of viral genomic studies has experienced an unprecedented increase in data volume. New strains of known viruses are constantly being added to the GenBank database and so are completely new species with little or no resemblance to our databases of sequences. In addition to this, metagenomic techniques have the potential to further increase the number and rate of sequenced genomes. Besides, it is important to consider that viruses have a set of unique features that often break down molecular biology dogmas, e.g., the flux of information from RNA to DNA in retroviruses and the use of RNA molecules as genomes. As a result, extracting meaningful information from viral genomes remains a challenge and standard methods for comparing the unknown and our databases of characterized sequences may need adaptations. Thus, several bioinformatic approaches and tools have been created to address the challenge of analyzing viral data. This chapter offers descriptions and protocols of some of the most important bioinformatic techniques for comparative analysis of viruses. The authors also provide comments and discussion on how viruses\' unique features can affect standard analyses and how to overcome some of the major sources of problems. Protocols and topics emphasize online tools (which are more accessible to users) and give the real experience of what most bioinformaticians do in day-by-day work with command-line pipelines. The topics discussed include (1) clustering related genomes, (2) whole genome multiple sequence alignments for small RNA viruses, (3) protein alignment for marker genes and species affiliation, (4) variant calling and annotation, and (5) virome analyses and pathogen identification.
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  • 文章类型: Journal Article
    急性白血病(AL)是一种危及生命的恶性疾病,发生在骨髓和血液中,分为急性髓系白血病(AML)或急性淋巴细胞白血病(ALL)。诊断AL认股权证测试方法,如流式细胞术,这需要训练有素的专业人员,时间,和钱。我们的目标是开发一种模型,可以对12种细胞类型的外周血图像进行分类,包括与AL相关的病理细胞,使用人工智能。
    我们从282例患者(82例AML,40与所有和160个未成熟粒细胞)。
    使用原始图像尺寸的EfficientNet-V2(B2)的性能表现出最大的精度(精度,0.8779;精度,0.7221;召回,0.7225;F1得分,0.7210)。EfficientNet-V1(B1)实现了次优精度,256×256像素的图像。对于具有原始图像大小的EfficientNet-V1(B1),F1得分最高。EfficientNet-V1(B1)和EfficientNet-V2(B2)用于开发集成模型,准确性(0.8858)和F1评分(0.7361)均有所提高。开发的集成模型对12种细胞类型的分类性能良好,受试者工作特征曲线下面积大于0.9,成髓细胞和淋巴母细胞的F1评分分别为0.8873和0.8006。
    开发的集成模型对12个细胞分类的性能令人满意,特别是成髓细胞和淋巴母细胞。我们相信,我们模型的应用将使难以快速准确诊断AL的医疗机构受益。
    UNASSIGNED: Acute leukemia (AL) is a life-threatening malignant disease that occurs in the bone marrow and blood, and is classified as either acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL). Diagnosing AL warrants testing methods, such as flow cytometry, which require trained professionals, time, and money. We aimed to develop a model that can classify peripheral blood images of 12 cell types, including pathological cells associated with AL, using artificial intelligence.
    UNASSIGNED: We acquired 42,386 single-cell images of peripheral blood slides from 282 patients (82 with AML, 40 with ALL, and 160 with immature granulocytes).
    UNASSIGNED: The performance of EfficientNet-V2 (B2) using the original image size exhibited the greatest accuracy (accuracy, 0.8779; precision, 0.7221; recall, 0.7225; and F1 score, 0.7210). The next-best accuracy was achieved by EfficientNet-V1 (B1), with a 256 × 256 pixels image. F1 score was the greatest for EfficientNet-V1 (B1) with the original image size. EfficientNet-V1 (B1) and EfficientNet-V2 (B2) were used to develop an ensemble model, and the accuracy (0.8858) and F1 score (0.7361) were improved. The classification performance of the developed ensemble model for the 12 cell types was good, with an area under the receiver operating characteristic curve above 0.9, and F1 scores for myeloblasts and lymphoblasts of 0.8873 and 0.8006, respectively.
    UNASSIGNED: The performance of the developed ensemble model for the 12 cell classifications was satisfactory, particularly for myeloblasts and lymphoblasts. We believe that the application of our model will benefit healthcare settings where the rapid and accurate diagnosis of AL is difficult.
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  • 文章类型: Journal Article
    轻度创伤性脑损伤(mTBI)已成为阿尔茨海默病和慢性创伤性脑病等神经退行性疾病发展的潜在危险因素。爆炸mTBI,由于暴露于爆炸产生的压力波,主要由军事人员经历,近几十年来患病率和严重性有所增加。然而,mTBI的潜在病理学在很大程度上是未知的。我们检查了人死后额叶皮层中AQP4的表达和定位,并观察到爆炸暴露后AQP4表达的明显层状差异。我们还观察到AQP4表达和定位的类似层状变化,以及在反复爆炸mTBI小鼠模型中爆炸伤后28天出现的淋巴功能延迟受损。在一群患有mTBI爆炸的退伍军人中,我们观察到爆炸暴露与额叶皮质MRI可见血管周围间隙的负担增加有关,一个假定的神经成像标记的淋巴血管周围功能障碍。这些发现表明,冲击伤后AQP4的变化和延迟的淋巴损伤可能使创伤后的大脑容易受到脑震荡后症状和慢性神经变性的影响。
    Mild traumatic brain injury (mTBI) has emerged as a potential risk factor for the development of neurodegenerative conditions such as Alzheimer\'s disease and chronic traumatic encephalopathy. Blast mTBI, caused by exposure to a pressure wave from an explosion, is predominantly experienced by military personnel and has increased in prevalence and severity in recent decades. Yet the underlying pathology of blast mTBI is largely unknown. We examined the expression and localization of AQP4 in human post-mortem frontal cortex and observed distinct laminar differences in AQP4 expression following blast exposure. We also observed similar laminar changes in AQP4 expression and localization and delayed impairment of glymphatic function that emerged 28 days following blast injury in a mouse model of repetitive blast mTBI. In a cohort of veterans with blast mTBI, we observed that blast exposure was associated with an increased burden of frontal cortical MRI-visible perivascular spaces, a putative neuroimaging marker of glymphatic perivascular dysfunction. These findings suggest that changes in AQP4 and delayed glymphatic impairment following blast injury may render the post-traumatic brain vulnerable to post-concussive symptoms and chronic neurodegeneration.
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  • 文章类型: Journal Article
    大规模的侧翼崩塌是与火山岛演化相关的主要危害之一。准确记录此类事件的日期对于评估失稳事件的频率和进一步评估与内部和/或外部因素相关的触发机制至关重要。比如火山动力学,区域构造,和全球古气候变化。这里,我们限制了弗洛雷斯岛(亚速尔群岛)东部侧翼暴露的富含浮石的火山碎屑矿床的年龄,我们将其解释为由主要的侧翼坍塌产生的共同爆炸沉积物,该坍塌摧毁了前火山大厦的整个西翼。12个单晶粒40Ar/39Ar分析,使用我们的高灵敏度多收集器NGX质谱仪在250-500µm的斜长石长石(平均K/Ca接近5)上进行,为这次喷发提供1.32±0.01Ma的稳健加权平均年龄。这一新年龄与先前K/Ar数据一致,该数据将侧翼塌陷范围定为1.30±0.04至1.18±0.09Ma,并表明此事件发生在火山主要建设阶段的末尾。爆炸产生了富含浮石的层,然后是拉哈,这由过时的沉积物下面的多遗传泥流沉积物证明。根据崩塌前后火山喷发的地球化学,我们推测岩浆过程对侧翼不稳定的可能作用。我们提出了第一个假设,即浅层岩浆储层的分化可能有利于建筑物的膨胀,地面震动,和侧翼失败,引发减压引起的剧烈喷发。总的来说,我们的研究表明,高灵敏度质谱仪现在已经达到分析性能,可以在相对较小和中等富含K的单长石上精确和准确地测量年龄,这对于确定第四纪晚期大规模侧翼塌陷可能引起的非均质爆炸和特法拉沉积物的年代至关重要。
    Large-scale flank collapses are one of the main hazards associated with the evolution of volcanic islands. Precisely dating such events is critical to evaluate the frequency of destabilization episodes and further assess the triggering mechanism(s) associated with internal and/or external factors, such as volcano dynamics, regional tectonics, and global paleoclimatic changes. Here, we constrain the age of a pumice-rich pyroclastic deposit exposed on the eastern flank of Flores Island (Azores), which we interpret as a co-blast deposit generated by a major flank collapse that destroyed the whole western flank of the former volcanic edifice. Twelve single-grain 40Ar/39Ar analyses, performed on 250-500 µm anorthoclase feldspars (mean K/Ca close to 5) with our high-sensitivity multi-collector NGX mass spectrometer, provide a robust weighted mean age of 1.32 ± 0.01 Ma for this eruption. This new age is consistent with previous K/Ar data bracketing the flank collapse between 1.30 ± 0.04 and 1.18 ± 0.09 Ma, and indicates that this event occurred at the end of the main construction phase of the volcano. The explosion produced pumice-rich layers preceded by a lahar as attested by a polygenetic mudflow deposit underlying the dated deposit. From the geochemistry of lavas erupted just before and after the collapse, we speculate upon the possible role of magmatic processes on flank destabilization. We propose a first hypothesis where differentiation in a shallow magma reservoir could have favored edifice inflation, ground shaking, and flank failure, triggering a decompression-induced violent eruption. Overall, our study shows that high-sensitivity mass spectrometers have now reached analytical performances allowing to measure precisely and accurately ages on relatively small and moderately K-rich single feldspars, which is of the utmost importance for dating heterogeneous blasts and tephra deposits that may have been induced by large-scale flank collapses during the late Quaternary.
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  • 文章类型: Journal Article
    背景:Ageratum属(菊科)的物种分布在世界各地。香菇和香菇是印度最常见的物种。这些物种在形态上非常相似,因此在野外调查和分类学验证过程中对鉴定提出了挑战。物种的准确鉴定非常重要,尤其是在具有医学意义时。为了克服形态学识别中的障碍,在本研究中已经使用了DNA条形码。
    结果:形态学和DNA条形码matK和ITS基因,用于区分香菇和香菇。将获得的matK和ITS基因序列提交给GenBank和BOLD系统以获得登录号。使用BLAST将DNA序列与数据库序列进行比对,并通过MEGA11软件中的近邻连接算法构建系统进化树。A.conyzoides的独特特征包括卵形至椭圆形长圆形的叶子,其楔形基部和花序头形成圆顶至平顶簇。然而,A.houstonianum具有三角形到卵形的叶子,具有心形到截短的基部,花序中的聚伞状簇,并规定腺状总苞片。matK基因已显示出最高的同一性百分比(100%),对于A.acyzoides。系统发育树分析已经证明了A.conyzoides和A.houstonianum与它们各自的物种密切相关,受matK和ITS树中的引导值支持。
    结论:这项研究表明,形态学和分子数据可以成功地用于鉴定合子A。matK和ITS条形码在鉴定Ageratum物种方面提供了有希望的结果,它们的系统发育支持在菊科中的分类。
    BACKGROUND: The species of genus Ageratum (family Asteraceae) are distributed in various parts of the world. Ageratum conyzoides and A. houstonianum are the most commonly occurring species in India. These species are quite similar in their morphology thus creating a challenge in identification during the field survey and taxonomic validation. The accurate identification of the species is highly significant especially when those are of medicinal interest. To overcome the barriers in morphological based identification, DNA barcoding has been employed during the present investigation.
    RESULTS: Morphological and DNA barcodes matK and ITS genes, were employed to differentiate between Ageratum conyzoides and A. houstonianum. The obtained matK and ITS gene sequences were submitted to GenBank and BOLD system to obtain accession numbers. The DNA sequences were aligned with database sequences using BLAST and phylogenetic trees were constructed through neighbor-joining algorithm in MEGA 11 software. The distinguish features of A. conyzoides include ovate to elliptic-oblong leaves with a cuneate base and inflorescence heads forming domed to flat-topped clusters. However, A. houstonianum has triangular to ovate leaves with a cordate to truncate base, cymose clusters in the inflorescence and stipulate glandular involucre bracts. The matK gene has shown the highest identity percentages (100%) for A. houstonianum and 99.87% for A. conyzoides. The phylogenetic tree analysis has demonstrated a close association of A. conyzoides and A. houstonianum with their respective species, supported by bootstrap values in the matK and ITS trees.
    CONCLUSIONS: This study revealed that morphological and molecular data can be successfully utilized in the identification of A. conyzoides and A. houstonianum. The matK and ITS barcodes provide promising results in the identification of Ageratum species, with their phylogeny supporting classification within the family asteraceae.
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