三维X射线显微技术与小型-微体化石高分辨率无损成像*

在古生物学研究中,以X射线断层成像(Computed Tomography)为代表的三维无损成像技术可以在不破坏化石标本的前提下,同时获得标本外观形态和内部结构的信息,相比传统的可见光成像手段有着明显优势。为推动化石三维无损成像技术在国内古生物学领域的发展,本文系统介绍一种新型显微CT技术——三维X射线显微术(Three-Dimensional X-ray Microscopy)。与基于几何放大和吸收衬度成像的传统显微CT技术相比,该技术有若干优势:(1)将同步辐射X射线显微断层成像的光学成像系统引入基于实验室X射线源的显微CT系统中,在几何放大的基础上增加了光学放大,优化了传统显微CT的系统架构,弥补了传统显微CT单纯依靠几何放大的不足,提高了空间分辨率;(2)采用可移动的X射线源和优化的光学成像系统,实现了低能X射线相位衬度成像,可以三维重构传统显微CT技术无法有效探测的、低吸收衬度的化石标本;(3)基于新的成像架构和成像算法,实现了厘米-分米级较大标本内部"感兴趣区域"(Region of Interest)精确导航和局部高分辨率(微米-亚微米空间分辨)成像;(4)可以实现小型扁平标本(宽厚比4,宽10cm)高效率、高分辨率成像和长条形微体标本长轴方向自动分段无缝拼接的微米至亚微米级高分辨率重建,弥补了传统工业显微CT针对小型扁平标本和长条形微体标本高分辨成像效果不佳的缺陷。这些优势使得基于实验室X射线源的显微CT成像技术可以获得接近同步辐射X射线源的成像质量,从而有效推动化石生物学研究。     

膜翅目广腰亚目化石及其在缅甸琥珀中的研究现状及展望

白垩纪缅甸琥珀昆虫化石研究是当前古昆虫学研究的热点之一。广腰亚目是膜翅目中的一个重要类群,其研究不仅为探讨膜翅目起源、早期演化、系统发育、不同地质时期古地理、古生态等方面提供重要的科学证据,而且可为陆地生态系统中的生物多样性研究提供重要材料。文中综述缅甸琥珀的研究简史及研究现状,阐述广腰亚目在印痕化石与缅甸琥珀中的特点、分布情况及该亚目在印痕化石与缅甸琥珀间的研究差异,进而探讨膜翅目广腰亚目化石当前研究现状、存在的问题及未来前景,并期望广大研究者增加对缅甸琥珀广腰亚目类群的关注和研究。     

白垩纪中期缅甸琥珀内真水龙骨类鳞片化石的发现及其意义

在白垩纪中期(～100 Ma)缅甸琥珀中首次报道了蕨类植物鳞片化石。该鳞片化石为基部着生,鳞片细胞壁均存在不同程度加厚,为筛孔状鳞片类型。根据最新的现代蕨类植物系统发育树,结合鳞片的演化趋势及鳞片化石的形态解剖特点分析,认为该鳞片化石来自真水龙骨类。这一发现表明真水龙骨类在白垩纪中期就已经出现了多样性分化。     

大肠杆菌细胞的软X射线显微成像研究

软X射线显微术是研究含水甚至活性生物样品的有力工具。相对于光学显微镜 ,它具有更高的成象分辨率 ;相对于电子显微镜 ,它的样品制备简单—无须对样品进行脱水、染色和超薄切片等。报道的是利用合肥同步辐射X射线源和接触显微成象技术 ,对自然状态下含水的完整XL1 blueMRF′细菌细胞进行显微成象研究。从获得的显微图象中可以看出一些新的现象。含有DNA、蛋白质的拟核以及中体对波长 2 .4nmX射线具有较弱的吸收能力 ;不少细菌细胞的两端对 2 .4nm波长的X射线的吸收也具有很大的差异。这些有趣现象产生的根本原因和生物学意义有待进一步研究。     

生物薄试样X射线显微定量分析技术的有效性研究

为了探讨生物薄试样的X射线显微定量分析(EPMA)技术的有效性,本文对Cliff-Lorimer因子(k因子)的计算值和EPMA测定值做了比较。结果显示生物试样中的一些主要元素如Cl,K,Ca的Cliff-Lorimer因子的计算值和EPMA测定值吻合得很好;还对不同含硫蛋白质试样中元素硫浓度计算值与EPMA测定值,及不同Ca²⁺含量试样中Ca²⁺浓度EPMA测定值与原子吸收光谱测定值做了比较。分别获得相关系数为0.994和0.989。这些结果说明用EPMA分析生物薄试样的结果是可以信赖的。     

反射X—射线驻波与膜的特征结构

本文评述了反射X─射线驻波（RXSW：ReflectedX－rayStandingWaves）技术的原理、特性和在膜结构与功能研究中的应用价值,报道了该技术目前的技术指标及今后的发展方向。     

同步辐射X射线吸收近边结构光谱技术在磷素固相形态研究中的应用

固相形态磷是控制环境中磷素生物可利用性、迁移流失能力的重要形态.基于同步辐射光源的X射线吸收近边结构(XANES)光谱技术可在分子水平上识别目标元素周围的局部化学信息,在非破坏性、原位直接表征等方面体现出其独特的优越性,成为表征化学物质存在形态和阐明化学反应微观机制的前沿技术之一,在环境化学领域中得到了广泛关注.本文简述了磷的XANES的基本理论,综述了XANES技术在矿物、土壤及有机肥中磷素固相形态研究中的应用进展,并分析了该技术应用在环境介质中磷形态表征中所面临的挑战及发展趋势,指出XANES技术应与其他微观光谱技术及宏观试验方法有机结合,多种表征技术取长补短,以期为环境介质中磷素形态表征及转化机制研究提供全面有效的技术支撑.     

Co2+-Tyr配合物的合成及X射线衍射分析

研究了Co2+-Tyr配合物的合成方法,探讨了合成工艺的主要影响因素,确定了最佳反应时间、温度、pH值及原料配比,采用X射线衍射光谱及元素分析对配合物结构进行了分析鉴定,结果表明Co2+能与Tyr形成配合物。     

水、甲醇、乙醇对含水脑磷脂液晶结构影响的X射线衍射研究

用小角X射线散射法(SAXS)对含水脑磷脂分别用水、甲醇和乙醇实验所形成的液晶体系结构进行了研究。实验结果证明:在脑磷脂-水体系中,随着水含量增加,脑磷脂和水形成的双分子层液晶体系的层间距变大;在脑磷脂-甲醇体系中,随着甲醇含量增加,它们的层间距变小。在脑磷脂-乙醇体系中,随着乙醇含量的增加,它们的层间距先由小到大,继而又由大变小,然后液晶相逐渐消失,最后变成液态。水和甲醇、乙醇相比,水有使层间距变大的趋势,醇类有使层间距变小的趋势,随着醇中碳链的增长,层间距减小的趋势增大。     

X射线对小鼠胰腺组织结构及血清胰岛素含量和胰淀粉酶活性的影响

探讨X射线对小鼠胰腺组织和血清胰岛素含量及胰淀粉酶活性的影响。将成年小鼠随机分为1Gy ,3Gy,5Gy实验组和0Gy对照组(每组20只),各组小鼠给予对应剂量X射线辐射(连续3d,每d一次),用生物显微技术观察胰腺组织结构的变化,用双抗体夹心法和比色法测定胰岛素含量及胰淀粉酶酶活性的变化。结果显示X射线辐射引起小鼠胰腺组织肿胀,细胞核变大,细胞变性、坏死;1Gy辐射组小鼠胰岛素含量与对照组相比有不同程度的升高,差异显著或极显著,3Gy和5 Gy辐射组小鼠胰岛素含量与对照组相比均下降,差异显著或极显著;3Gy辐射组小鼠淀粉酶活性相比对照组均有不同程度的升高,差异显著或极显著;5Gy辐射组小鼠淀粉酶活性较对照组降低,差异极显著。结果表明X射线影响小鼠胰腺组织结构及血清胰岛素含量和血清胰淀粉酶活性。     

Burmaphlebia reifi gen. et sp. nov., the first anisozygopteran damsel-dragonfly (Odonata: Epiophlebioptera: Burmaphlebiidae fam. nov.) from Early Cretaceous Burmese amber

A new family, genus and species of damselfly, Burmaphlebia reifi gen. et sp. nov. (Burmaphlebiidae fam. nov.), is described as the second fossil odonate from Early Cretaceous Burmese amber. Its phylogenetic position is discussed and the fossil is attributed to a new family at the base of the anisozygopteran grade, probably closely related to the Recent relict group Epiophlebiidae. It is the first record of the ‘anisozygopteran’ grade from amber and the smallest known representative of this group.http://zoobank.org/6EFE7288-BD89-42F9-BFA5-804CE6B904A6     

A catalogue of Burmite inclusions

Burmite (Burmese amber) from the Hukawng Valley in northern Myanmar is a remarkable valuable and obviously the most important amber for studying terrestrial diversity in the mid-Cretaceous.The diversity of Burmite inclusions is very high and many new taxa were found,including new order,new family/subfamily,and new genus.Till the end of 2016,14 phyla,21 classes,65 orders,279 families,515 genera and 643 species of organisms are recorded,which are summized and complied in this catalogue.Among them,587 species are arthropods.In addtion,the specimens which can not be identified into species are also listed in the paper.The information on type specimens,other materials,host and deposition of types are provided.     

Burmese amber: evidence of Gondwanan origin and Cretaceous dispersion

Abstract

Burmese amber is an extremely important source of mid-Cretaceous plant and animal remains with over 870 species of organisms, ranging from protozoa to vertebrates, described from this source. The amber mines are located on the West Burma Block that according to geologists was originally part of Gondwana. The present study introduces some angiosperms and insects in Burmese amber whose closest extant relatives have a Gondwanan distribution and there is no previous evidence of a Laurasian distribution. Based on this evidence, it is proposed that organisms in Burmese amber represent a selection of tropical to subtropical life forms that inhabited the interconnected continents of Gondwana in the Early Cretaceous. Based on the fossil record of angiosperms and their diversity in Burmese amber, the West Burma Block could not have rafted from Gondwana to SE Asia before the Early Cretaceous.     

New tribes of the superfamily Curculionoidea (Coleoptera) in Burmese amber

Two new tribes in the Curculionoidea are described as the Anchineini Poinar and Legalov, n. trib. (Ithyceridae: Carinae) and Paleocryptorhynchini Poinar and Legalov, n. trib. (Curculionidae: Erirhininae). The genus Anchineus Poinar and Brown, 2009, n. placem. is transferred from the subfamily Curculioninae of the family Curculionidae to the subfamily Carinae of the family Ithyceridae. The genus Paleocryptorhynchus Poinar, 2009, n. placem. is transferred from the subfamily Cryptorhynchinae to the subfamily Erirhininae. The placement of the genus Mesophyletis Poinar, 2006 in the family Ithyceridae was confirmed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:0C0039DD-7BC6-4A54-9282-F43C5606D68B     

Doratomantispa burmanica n. gen., n. sp. (Neuroptera: Mantispidae), a new genus of mantidflies in Burmese amber

A new genus and new species of mantidflies, Doratomantispa burmanica n. gen., n. sp. (Neuroptera: Mantispidae), is described from Burmese amber. Diagnostic characters of the new genus are small body size, trichosors present around entire wing margin except basally, protarsus 5-segmented with paired, simple claws but no aroleum, profemur bearing six cuticular spines, inner surface of protibia with row of peg-like protrusions, Sc meets R₁ in region of pterostigma, costal space greatly narrows toward wing apex, with 16 veinlets in costal space on front wing while costal veinlets on hind wing are replaced by trichosors and CuP absent in hind wing. The abdomen of the mantidfly is filled with large spheres resulting from a possible rickettsial infection. Phoretic heterostigmatid mites are adjacent to the wings of the fossil.     

Paleoleishmania proterus n. gen., n. sp., (Trypanosomatidae: Kinetoplastida) from Cretaceous Burmese amber

A trypanosomatid (Trypanosomatidae: Kinetoplastida) associated with a blood-filled female sand fly in Cretaceous Burmese amber, is described in the new genus and species, Paleoleishmania proterus. The genus Paleoleishmania is established as a collective genus for digenetic fossil trypanosomes associated with sand flies. Amastigotes, promastigotes and paramastigotes are described. Paleoleishmania proterus is the first fossil kinetoplastid and provides a minimum age for the digenetic Trypanosomatidae. Its discovery indicates that vector-borne pathogens had been established by the Early Cretaceous.     

Protoresinacarus brevipedis gen. n., sp. n. from Early Cretaceous Burmese amber: the first fossil record of mites of the Family Resinacaridae (Acari: Heterostigmata: Pyemotoidea)

A new genus and species of mites, Protoresinacarus brevipedis gen. n., sp. n. (Acari: Heterostigmata: Pyemotoidea), is described from Early Cretaceous Burmese amber. This represents the first fossil record of a member of the family Resinacaridae. It is represented by 21 phoretic females adjacent to an adult mantidfly (Neuroptera: Mantispidae). This is the first record of phoresy of pyemotid mites on members of the insect order Neuroptera. The fossil mites differ from extant members of the family in possessing distinctly shorter legs I, which do not reach beyond the apex of the gnathosoma, and by the long setae v ₁, v ₂ and c ₂.