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我国科学家发现古老细菌化石 揭示地球与生命协同演化奥秘_我的网站

A |     United Kingdom Prime Minister Boris Johnson has accused the Indian authorities of “arbitrarily” detaining British-Sikh national who has been lodged in a prison in the northern state of Punjab since 2017, according to British media reports.,Johal, a resident of the Scottish town of Dumbarton, has been charged by India’s National Investigative Agency (NIA), the federal counter-terrorism organization, of being a member of banned Khalistan Liberation Front (KLF). Johal was arrested while he was in Punjab for his wedding in November 2017.,The KLF advocates for a separate Sikh homeland, or Khalistan, primarily comprising the Indian state of Punjab. The Khalistan movement in India reached its peak in the 1980s, when a military crackdown on the separatists culminated in the assassination of former Prime Minister Indira Gandhi by her Sikh bodyguards, who were unhappy with New Delhi’s actions.,Khalistani Flags, Slogans Found at Himachal Pradesh State Assembly Prompt Police Probe8 May, 08:07 GMT,Johal is one of the KLF aides named in a chargesheet in the killing of Ravindra Gosain, a member of India’s Rashtriya Swayamsevak Sangh (RSS), in October 2017. The RSS is the ideological parent of India’s ruling Bharatiya Janata Party (BJP). Johal’s brother in Scotland, who has been running a media campaign, denies the charges levelled against him.,However, his arrest in India, has sparked outrage among Sikh groups in the UK and Scotland, with Opposition Leader Keir Starmer as well as several other Labour Party parliamentarians having urged the Boris Johnson administration to negotiate his release with the Indian government.,“Ministers and officials of the Government have consistently raised the UK’s concerns directly with the Government of India about Mr. Johal’s treatment and his right to a fair trial. We have done so on almost a hundred occasions since Mr. Johal’s detention in November 2017,” Johnson wrote in a letter dated 21 June to Starmer, but it was only reported in UK media on Thursday.,Prior to surfacing of the letter, the United Nations' Working Group on Arbitrary Detention also stated back in May that Johal has been “arbitrarily” detained in India.,It called upon New Delhi to “take urgent action to ensure the immediate unconditional release” of Johal and award him “compensation” as well as other “reparations, in accordance with international law”.,'Promoting Hatred': India Condemns Resolution in US' Connecticut Recognising 'Sikh Independence'2 May, 06:26 GMT,Since his arrest, New Delhi has maintained that Johal’s rights have been respected. At the same time, the Indian government has raised concerns over the activities of Khalistani separatists, many of who are based in the United Kingdom, Canada and even the US.,Johnson was in India for a state visit in April. Back then, he had revealed that the UK was “sensitive” to India’s concerns on Khalistani extremism.,“We have a very strong view in the UK that we don’t tolerate extremist groups. We have set up an anti-extremist task force to help India,” Johnson said during the visit.,More recently, Johnson met Prime Minister Narendra Modi on the sidelines of the G-7 Summit in Germany this week. As of now, it remains unclear if the issue was raised during the meeting.,Want to know more? Check out our Koo & Telegram accounts!,Koo: https://www.kooapp.com/profile/sputniknews,Sputnik India: https://t.me/sputniknewsindia。    人民网西安4月21日电（记者李志强）近日，记者从西北大学获悉，该校早期生命与环境研究团队与中国科学院地质与地球物理研究所、上海交通大学等单位科学家合作，在5.18亿年前的寒武纪清江生物群中发现多细胞结构的丝状硫酸盐还原细菌化石清江丝菌，并结合分子生物学分析结果，还原了硫酸盐还原菌与地球环境协同演化历史。　　细菌化石是指保存在岩石中的细菌遗体或其活动留下的痕迹。据专家介绍，在此之前，除了少数有特殊形貌的蓝细菌化石和趋磁细菌磁小体化石外，在古老地质记录中还没有发现可靠的硫酸盐还原细菌化石。硫酸盐还原菌的演化与地球环境变化的关系，科学界也没有明确的认识。　　清江丝菌化石的产地和环境背景。

B | (a)早寒武纪扬子台地岩相古地理图和清江丝菌及所属清江生物群的化石产地；（b）清江生物群生态复原图 西北大学供图　　团队成员、西北大学教授张兴亮介绍，硫酸盐还原细菌是一类在厌氧条件下生活的微生物，它们利用硫酸盐氧化有机碳来获取能量，并在此过程中将硫酸盐还原产生代谢产物硫化氢。这些细菌在环境科学、生态学和工业领域中都具有极为重要的意义。它们是地球硫循环的关键推动者，通过还原硫酸盐参与到硫的生物地球化学循环中，影响硫在不同价态和形态间的转化。同时，它们也参与有机质的分解和甲烷氧化等过程，从而调节海洋的氧化还原状态和温室气体排放。　　研究团队根据化石证据和谱系基因组学分析结果，提出硫酸盐还原菌与地球氧化事件协同演化假说，认为脱硫细菌门首先在24亿年前的大氧化事件期间发生辐射演化，约8.5亿年前演化出丝状多细胞种类；在新元古代末期，地球第二次氧化事件导致海底广泛氧化，丝状种类约在5.6亿年前获得传导电子功能，硫酸盐还原通路逆转，演化成可以跨越氧化还原界面，一端在还原带氧化硫，另一端在氧化带还原氧的电缆细菌。清江丝菌化石的多细胞丝状体形态。

C | 西北大学供图　　据介绍，这项研究是古生物学、地球化学、谱系基因组学交叉合作的结果，同时借助了多种高分辨率、高精度显微和微区原位分析技术，是在多学科交叉背景下探究微生物硫酸盐还原作用与地球环境协同演化的首次尝试，对融合利用显微学和基因组学等最新技术、促进地学与生物学前沿交叉、探索解决地球与生命协同演化等具有重要意义。　　同时，这项研究还能够为科学家探讨“生命在火星等其他行星上的存在、演化的可能性研究”提供参考，为人类寻找地外生命提供了一种可能的途径。

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