Ostracods and the Holocene palaeolimnology of Lake Qarun, with special reference to past human–environment interactions in the Faiyum (Egypt)

We present an ostracod record covering the past two millennia from an 8.25-m core taken from Lake Qarun, in the Faiyum Depression of Egypt. The occurrence of ostracod species in the lake is controlled primarily by variations in solute composition, which are in turn related to shifts in catchment land use. At times when the Faiyum Depression supported thriving agriculture, lake water contained Na⁺–Cl^? brine, and Cyprideis torosa dominated the ostracod assemblage. When the Faiyum Depression experienced periods of environmental and economic decline, lake water contained Na⁺–HCO₃ ^? brine, and Limnocythere inopinata dominated. The relative abundance of other ostracod species provides additional information about past conditions in Lake Qarun including salinity and lake level changes. Overall, the ostracod assemblages provide evidence for human influences in the Faiyum, which extend back before instrumental or detailed observational records began.     

滤光膜对喜树幼苗叶片生长和喜树碱含量的影响

喜树 (Camptotheca acuminata)为中国特有树种 ,因其次生代谢产物喜树碱具有抗癌作用而闻名。通过用黄色、红色、蓝色 3种滤光膜对温室栽培的喜树幼苗进行遮光处理 ,研究了不同光照环境下喜树幼苗叶片生物量、叶绿素含量、光合作用和喜树碱含量的差异。结果表明在 30 d的遮光过程中 ,红膜和蓝膜遮光明显导致幼苗叶片生物量降低 ,黄膜遮光下幼苗叶片生物量在处理后 2 5 d才表现明显降低。不同滤光膜下幼苗叶片叶绿素含量先降低然后升高 ,遮光幼苗的叶绿素 a/ b明显低于日光幼苗。幼苗日最大净光合速率的顺序是 :日光 >黄膜 >红膜 >蓝膜。处理后第 2 0天 ,不同滤光膜下幼苗的光饱和光合速率 (Amax)、光饱和点 (Is)、光补偿点 (Ic)、最大表观量子效率 (AQYmax)都不同程度的低于日光幼苗。处理后第 10天至第 30天 ,遮光幼苗叶片喜树碱含量均显著高于日光下幼苗 ,以蓝膜下幼苗的喜树碱含量最高。蓝膜和黄膜下幼苗的喜树碱产量在后期处理中显著高于日光下幼苗 ,蓝膜下幼苗喜树碱产量在第 30天最高 ,是日光下幼苗的 2 .4 9倍。红膜下幼苗的喜树碱产量在第 10天后与日光下幼苗差异不显著。通过滤光膜遮光促进喜树碱在幼苗叶片中的积累 ,提高了叶片喜树碱产量 ,对喜树碱的生产实践有一定的意义     

Elaboration of cellulose fibrils by Agrobacterium tumefaciens during attachment to carrot cells.

The attachment of virulent strains of Agrobacterium tumefaciens to plant cells is the first step in the bacterial induction of tumors. Binding of A. tumefaciens to carrot tissue culture cells occurred as a two-step process. The initial step was the attachment of the bacteria to the plant cell wall. Living plant cells were not required. Bacterial attachment to heat-killed or glutaraldehyde-fixed carrot cells proceeded with only slightly altered kinetics and unaltered bacterial strain specificity. After the bacteria bound to the carrot cell surface, scanning electron microscopy showed that fibrils developed, surrounded the bacteria, and anchored them to the plant cell surface. These fibrils were synthesized by the bacteria and not by the plant cell since they were also made after the attachment of A. tumefaciens to dead carrot cells and since under some conditions the bacteria synthesized fibrils in the absence of plant cells. Calcofluor staining, acid hydrolysis, enzymatic digestion studies, and infrared spectroscopy showed that the fibrils were composed of cellulose. The formation of these cellulose fibrils occurred during the attachment of virulent strains of A. tumefaciens to plant cells in vitro. The fibrils anchored the bacteria to the plant cell surface and entrapped additional bacteria. The multiplication of entrapped and attached bacteria resulted in the formation of large clusters of bacteria held close to the plant cell wall and plasma membrane by cellulose fibrils. This high concentration of bacteria may facilitate transfer of Ti plasmid deoxyribonucleic acid to the plant cell resulting in the formation of tumors.     

X-ray diffraction studies on oriented gels of vertebrate smooth muscle thin filaments.

The ATPase activity of acto-myosin subfragment 1 (S1) at low ratios of S1 to actin in the presence of tropomyosin is dependent on the tropomyosin source and ionic conditions. Whereas skeletal muscle tropomyosin causes a 60% inhibitory effect at all ionic strengths, the effect of smooth muscle tropomyosin was found to be dependent on the ionic strength. At low ionic strength (20 mM) smooth muscle tropomyosin inhibits the ATPase activity by 60%, while at high ionic strength (120 mM) it potentiates the ATPase activity three- to five-fold. Therefore, the difference in the effect of smooth muscle and skeletal muscle tropomyosin on the acto-S1 ATPase activity was due to a greater fraction of the tropomyosin-actin complex being turned on in the absence of S1 with smooth muscle tropomyosin than with skeletal muscle tropomyosin. Using well-oriented gels of actin and of reconstituted specimens from vertebrate smooth muscle thin filament proteins suitable for X-ray diffraction, we localized the position of tropomyosin on actin under different levels of acto-S1 ATPase activity. By analysing the equatorial X-ray pattern of the oriented specimens in combination with solution scattering experiments, we conclude that tropomyosin is located at a binding radius of about 3.5 nm on the f-actin helix under all conditions studied. Furthermore, we find no evidence that the azimuthal position of tropomyosin is different for smooth muscle tropomyosin at various ionic strengths, or vertebrate tropomyosin, since the second actin layer-line intensity (at 17.9 nm axial and 4.3 nm radial spacing), which was shown in skeletal muscle to be a sensitive measure of this parameter, remains strong and unchanged. Differences in the ATPase activity are not necessarily correlated with different positions of tropomyosin on f-actin. The same conclusion is drawn from our observations that, although the regulatory protein caldesmon inhibits the ATPase activity in native and reconstituted vertebrate smooth muscle thin filaments at a molar ratio of actin/tropomyosin/caldesmon of 28:7:1, the second actin layer-line remains strong. Only adding caldesmon in excess reduces the intensity of the second actin layer-line, from which the binding radius of caldesmon can be estimated to be about 4 nm. The lack of predominant meridional reflections in oriented specimens, with caldesmon present, suggests that caldesmon does not project away from the thin filament as troponin molecules in vertebrate striated muscle in agreement with electron micrographs of smooth muscle thin filaments. In freshly prepared native smooth muscle thin filaments we observed a Ca(2+)-sensitive reversible bundling effect.(ABSTRACT TRUNCATED AT 400 WORDS)     

铁剥夺在TPA 诱导K562 细胞分化中对细胞 生长分化及EGR1mRNA 表达的影

目的：通过,IPA诱导K562细胞分化过程中干预细胞铁代谢探讨白血病细胞铁与细胞分化的关系及对EGR1mRNA表达的影响。方法：应用体外细胞培养技术通过细胞形态,细胞化学染色观察细胞生长分化情况;用FCM、RT—PCR等技术检细胞周期、细胞表面分化抗原CD33、CD14及EGR1mRNA的表达。结果：在,IPA诱导K562细胞分化过程中铁剥夺可明显抑制K562细胞生长,并可阻止,IPA诱导K562细胞分化,使K562细胞停止在S期。铁剥夺可降低,TPA诱导K562细胞分化过程中EGR1mRNA的表达。讨论：铁剥夺明显抑制K562细胞生长、阻止TPA诱导K562细胞分化,故铁剥夺剂（DFO）可能作为一种辅助抗癌药用于白血病的化疗,但由于它能阻止白血病细胞的分化,故不宜用于白血病的诱导分化治疗。铁剥夺使K562细胞分化过程中E—GR1mRNA表达降低可能参与了阻止TPA诱导K562细胞的分化过程。     

NMR spectroscopy based metabonomic studies on the comparative biochemistry of the kidney and urine of the bank vole (Clethrionomys glareolus), wood mouse (Apodemus sylvaticus), white toothed shrew (Crocidura suaveolens) and the laboratory rat

The metabolic profiles of three wild mammals that vary in their trophic strategies, the herbivorous bank vole (Clethrionomys glareolus), the granivorous wood mouse (Apodemus sylvaticus), and the insectivorous white-toothed shrew (Crocidura suaveolens), were compared with that of a widely used strain of laboratory rat (Sprague Dawley). In conjunction with NMR spectroscopic investigations into the urine and blood plasma composition for these mammals, high resolution magic angle spinning (HRMAS) 1H-nuclear magnetic resonance (NMR) spectroscopy was applied to investigate the composition of intact kidney samples. Adaptation to natural diet affects both renal metabolism and urinary profiles, and while these techniques have been used to study the metabolism of the laboratory rat little is known about wild small mammals. The species were readily separated by their urinary profiles using either crude metabolite ratios or statistical pattern recognition. Bank vole urine contained higher concentrations of aromatic amino acids compared with the other small mammals, while the laboratory rats produced relatively more hippurate. HRMAS 1H-NMR demonstrated striking differences in both lipid concentration and composition between the wild mammals and Sprague Dawley rats. Bank voles contained high concentrations of the aromatic amino acids phenylalanine, tyrosine and tryptophan in all tissue and biofluids studied. This study demonstrates the analytical power of combined NMR techniques for the study of inter-species metabolism and further demonstrates that metabolic data acquired on laboratory animals cannot be extended to wild species.     

小鼠精子形成各阶段转基因效率的研究

在过去的近30年中,转基因技术在哺乳动物基因表达方面研究的应用已经成为实验生物学及应用生物学领域最为显著的进展之一．传统的制作转基因动物方法有显微注射法、逆转录病毒感染法和胚胎干细胞法等,但每种方法都有其缺陷,限制了其在今后转基因动物研究中的广泛应用．对小鼠体内生殖细胞进行外源基因转染,研究精子形成过程中制作转基因小鼠的效率．首先运用睾丸注射法将被脂质体包裹的绿色荧光蛋白表达载体(pIRES2-EGFP)注射到公鼠睾丸及附睾内,然后根据精子形成的不同阶段,分别于注射后7、16、30和42天与发情母鼠合笼,利用PCR和DNA印迹方法对新生小鼠进行基因组DNA检测．在各阶段所得新生小鼠中PCR阳性率分别为6.82%、0、56.86%和42.86%,DNA印迹检测阳性率分别为6.82%、0、47.06%、34.69%．经活体荧光成像系统及荧光显微镜分析,转基因小鼠呈现绿色荧光表达．通过比较精子生成各阶段转基因效率高低,为以后通过用睾丸内注射法转染雄性生殖细胞高效制作转基因动物提供了理论依据．     

破色期番茄果实均一化cDNA沉默文库的构建和功能基因筛选模型的初步建立

番茄果实的成熟是由多基因精细调控的一个过程．利用破色期番茄果实,根据复性动力学原理在mRNA水平进行均一化操作使高丰度和低丰度的mRNA丰度接近．然后把均一化之后mRNA反转录得到cDNA,再与基因沉默载体pTRV重组,最后把构建好的载体通过电转化的方法转入到GV3101农杆菌中,从而建立起破色期番茄果实均一化cDNA沉默文库．通过番茄果实中病毒诱导基因沉默技术,对cDNA沉默文库进行初步筛选,从而确定功能基因筛选模型．在模型建立阶段,以番茄红素合成途径相关的PDS基因作为内标基因,在100个混合农杆菌样中,成功筛选到了PDS基因．     

球蚧跳小蜂属一新种记述(膜翅目,跳小蜂科)

记述采自辽宁省沈阳市北陵公园云杉球蚧Physokermes sp.上的跳小蜂1新种:云杉球蚧跳小蜂Aphycoides marginalis sp.nov.,所有模式标本均保存于东北林业大学昆虫标本室.     

实验性大鼠溃疡性结肠炎菌群失调的诊断及复方树舌的治疗观察

目的探讨对溃疡性结肠炎厌氧菌菌群失调简便检查方法,寻找有效治疗溃疡性结肠炎的中药合剂。方法用冰乙酸诱发大鼠结肠炎模型,用复方树舌中药治疗,在治疗期间分别检测每组大鼠厌氧菌代谢产物、挥发性脂肪酸的含量、了解肠厌氧菌群改变,一般切片行HE染色,观察病理变化。结果（1）模型组大鼠挥发性脂肪酸明显低于正常组（P〈0．05）;pH从第2天起升高明显高于正常对照组（P〈0．05）,各治疗组与自然恢复组比较差异有显著性（P〈0．05）。（2）自然恢复组与各用药组间的炎症评分比较P〈0．01,各治疗组间比较,树舌加丽珠肠乐组组织损伤评分小（P〈0．05）。结论（1）测定厌氧菌的代谢产物挥发性脂肪酸含量,即可对肠内厌氧菌菌群失调做出判断。（2）实验证明,复方树舌中药可作为益生元调节肠道菌群失调及黏膜的修复,对溃疡性结肠炎疗效显著。