原子力显微镜研究不同温度下质粒DNA结构变化

采用原子力显微镜（ＡＦＭ）在无水乙醇中成象了ｐＢＲ３２２质粒ＤＮＡ。在不同温度范围加热云母表面的ＤＮＡ溶液,并在相应温度下干燥使ＤＮＡ充分展开地固定在云母基底上。ＡＦＭ观察结果表明：在３０～４０℃,质粒ＤＮＡ主要是超螺旋和环状分子;在４０～５０℃,环状分子开环形成线形分子;　在７０～８０℃,这些线形分子全部变性,解链形成无规线团。我们通过测定ｐＢＲ３２２质粒ＤＮＡ的熔融曲线,发现了两个突变点,对应于ＡＦＭ所观察到的质粒ＤＮＡ在加热过程中由环状变成线形、双螺旋解开成单链的两个结构变化过程。这是首次通过ＡＦＭ直接观察到质粒ＤＮＡ在不同温度下的结构变化。     

利用原位杂交技术检测免疫球蛋白重链mRNA在T和B淋巴瘤内的表达

应用原位杂交技术和免疫组织化学法对８例Ｂ淋巴瘤和４例Ｔ淋巴瘤进行了ＩｇＨｍＲＮＡ和ＩｇＭ,κ,λ的检测。结果显示,８例Ｂ淋巴瘤ＩｇＨｍＲＮＡ均为阳性,位于胞核周围,有的ｍＲＮＡ阳性反应成点状位于胞质的一侧。７例胞质中ＩｇＭ,κ或λ为阳性。１例胞质内无ＩｇＭ,κ或λ,但胞核内ＩｇＨｍＲＮＡ阳性反应成点状分布,可能是初级ＲＮＡ转录。在Ｔ淋巴瘤中,只有一例胞核内出现初级ＲＮＡ转录,因为早期Ｔ淋巴瘤,也有Ｄ、Ｊ基因片段的重排     

LARGE SCALE RIPPLES IN SILURIAN LIMESTONES

Large scale ripple marks occur in Silurian (Landovery-Wenlock) limestones of the Oslo fjord area, Southern Norway. The limestones are biosparites with a drifted assemblage of fossils and sandstone pebbles.
Ripple cross-lamination is developed. It is concluded that the limestones accumulated under the action of strong currents. Features of the ripple cross-lamination suggest that these currents may have been tidal in origin.     

陕南寒武系宽川铺组具多级四分体细胞结构的微体化石*

我国华南扬子板块埃迪卡拉纪—寒武纪的含磷地层中产有丰富的呈现分裂特征的多细胞球状化石。由于有效信息的缺乏,长期以来,这些球状化石的生物属性及分类存在争议。我们在陕南寒武系宽川铺组获得的一些保存精美的分裂型球状化石,具有明显的多级四分体结构,通过与同层位产出的动物卵裂期胚胎化石、瓮安生物群中四分体结构的藻类化石对比,结果表明这些分裂球形化石很可能为多细胞藻类。     

付里叶变换红外光谱法研究水在稳定多肽构象中的作用

在０—１００％相对湿度（ＲＨ）范围内用竹里叶变换红外光谱研究了水合对聚赖氨酸溴化氢结合物构象的影响。随相对湿度ＲＨ增加,水合分为：无规卷曲、β－折叠和α－螺旋三个稳定的阶段．多肽的水合行为远比报导的复杂,在三个阶段中都不是纯单一结构组分,在任何一个ＲＨ下都存在３－４个吸收组分。在ＲＨ＞４４％以上β特征吸收发生复杂变化,表明β－结构的类型可能发生变化。实验表明,水是肽链柔性的增塑剂,运动性和构象的催化剂。     

贵州台江下-中寒武统凯里组遗迹化石群落与环境关系的探讨

通过贵州台江凯里组中丰富的、分异度较高的、以原地埋藏为特征的遗迹化石的研究,探讨凯里组遗迹化石群落的沉积环境和埋藏环境。凯里组遗迹化石群落以节肢动物和软体动物的停息迹、爬行迹和游泳迹占优势,浅层内生爬行觅食潜穴和系统觅食潜穴占有一定的地位,也见有浅的居住滤食性潜穴,属Seilacher的Cruziana遗迹相,为正常浪基面和风暴浪基面之间的浅海软质基底陆棚低能环境,那里盐度正常、光照充足、含氧量充分、水体平静、沉积速率较快。在此环境中,浮游、游泳以及底栖爬行和固着生物类型大量地生长、繁殖和活动,表生遗迹和浅层内生遗迹十分丰富。生物死亡后的腐烂和分解,使得食泥生物大量繁盛。随着沉积物的覆盖和被埋藏生物遗体的分解、腐烂,沉积物内部还原能力逐渐增强,导致分解和腐烂过程终止。     

华北板块西缘甘肃平凉上奥陶统平凉组灰岩微相和沉积环境

甘肃平凉官庄剖面为上奥陶统平凉组的建组剖面,出露其完整的地层序列,主要由细砂、粉砂级颗粒的碎屑岩和灰岩构成。该地区在平凉组沉积时期的构造背景属华北板块西部,位于鄂尔多斯古陆西缘。对官庄剖面平凉组灰岩夹层开展的微相分析显示其中含有丰富的泥状灰岩砂屑,生屑种类含量偏低且破碎程度高,无浅海区特有的沉积构造,海水深度不利于底栖生态群落栖居。灰岩的沉积学机制指示鄂尔多斯古陆西南海区存在较陡的海底地貌,这些内碎屑不是原地或近原地沉积的,它们最初产生于浅海碳酸盐岩台地,经重力流、等深流长距离搬运后到达接近秦岭-祁连海槽的深水区沉积。     

付里叶变换红外光谱法研究胰岛素的二级结构

付里叶变换红外光谱法测定了胰岛素的二级结构,讨论了信/噪比、谱解析、曲线拟合和吸收组分的指认对结构测定的影响。测定的胰岛素二级结构与X—光结构分析结果吻合。     

豫西地区早三叠世微生物成因沉积构造的微观特征

随着微生物沉积学的诞生与发展,地质记录中微生物席活动相关沉积构造已被广泛识别和报道。但是微生物成因沉积构造的判别仍建立在与现代微生物席宏观形态特征的对比与猜测基础之上。微生物成因沉积构造微观特征和直接成因证据的缺乏,使微生物沉积学的进一步发展遇到了严重障碍。豫西地区早三叠世陆相碎屑岩地层中发育丰富的微生物成因沉积构造类型,为微生物成因沉积构造的微观特征研究提供了良好材料。研究显示,微生物成因沉积构造具有特征明显的微观特征。除之前报道的悬浮颗粒、微生物纹层等特征外,本次研究还在光学薄片中发现了圈层结构的微生物扰动颗粒,在扫描电镜下发现了类型多样的微体生物化石。对微生物成因沉积构造微观特征的观察,丰富了微生物成因沉积构造的判别依据,为微生物沉积学发展与应用提供了新的材料和新的视角。     

HETEROGENEITY OF OXYGEN PRODUCTION AND CONSUMPTION IN A PHOTOSYNTHETIC MICROBIAL MAT AS STUDIED BY PLANAR OPTODES

By applying planar optodes and imaging techniques to a benthic photosynthetic mat, we demonstrated an extensive vertical and horizontal variation in O₂ concentrations, O₂ consumption, and O₂ production. In light, the oxic zone could be divided into three horizons: 1) an upper zone dominated by diatoms that had a moderate net O₂ production, 2) another zone dominated by Microcoleus-like cyanobacteria with a high net O₂ production, and 3) a lower zone with disintegrating microalgae and cyanobacteria with a high O₂ consumption rate. From the O₂ images, the net O₂ production/consumption was calculated at a spatial resolution of 130 μM. This allowed us to identify microsites with high rates of O₂ turnover within the photic zone. Sites with high net O₂ consumption (>1.5 nmol·cm^?3·s^?1) were typically situated next to sites with a relatively high net production (>2 nmol·cm^?3·s^?1), revealing a mosaic in which the highest O₂ consumption sites were surrounded by the highest O₂ production sites. This suggested a tight spatial coupling between production and consumption of O₂ within the photic zone. Light stimulated the O₂ consumption within the photic zone. At irradiances above 400 μmol photons·m^?2·s^?1, the stimulated O₂ production was almost completely balanced by enhanced O₂ consumption at microsites exhibiting net consumption of O₂ even at maximum irradiance (578 μmol photons·m^?2·s^?1). Our observations strongly supported the idea that light-stimulated respiration was caused by stimulated heterotrophic activity fueled by organic carbon leakage from the phototrophs. Despite microsites with high net O₂ consumption, anoxic microniches were not encountered in the investigated mat. Images of gross photosynthetic rates also revealed an extensive horizontal variation in gross rates, with microsites of low or no photosynthesis within the otherwise photic zone. Calculations based on the obtained images revealed that at maximum light (578 μmol photons·m^?2·s^?1), 90% of the O₂ produced was consumed within the photic zone. The presented data demonstrate the great potential offered by planar optode for studies of benthic photosynthetic communities.     

磷脂模型膜的时间分辨纳秒荧光光谱的研究

叙述了用时间分辨率纳秒荧光技术研究大豆磷脂或合成磷脂模型膜（脂质体）的物理状态变化与荧光寿命以及时间分辨各向异性测量参数变化相关性的实验结果。用荧光探剂ＭＣ５４０标记模型膜的结果表明,荧光寿命（τ）的变化与脂质／探剂比例、磷脂组成、磷脂的极性头部、脂肪酸酰链长度等有关。用ＤＰＨ（１,６－ｄｉｐｈｅｎｙｌ－１,３,５－ｈｅｘａｔｒｉｅｎｅ）标记磷脂模型膜的时间分辨各向异性分析结果表明,序参数（Ｓ）、     

激光感生NADH荧光研究生物体的新陈代谢

我们用激光荧光术对与生物体新陈代谢有密切联系的NADH分子进行了研究,测量了溶液的浓度、pH值和温度对NADH荧光光谱的影响,并对小白鼠的心脏和人工培养的心肌细胞中注入药物后的新陈代谢进行了测量.