Synchronizing rock clocks of Earth history

Calibration of the geological time scale is achieved by independent radioisotopic and astronomical dating, but these techniques yield discrepancies of approximately 1.0% or more, limiting our ability to reconstruct Earth history. To overcome this fundamental setback, we compared astronomical and 40Ar/39Ar ages of tephras in marine deposits in Morocco to calibrate the age of Fish Canyon sanidine, the most widely used standard in 40Ar/39Ar geochronology. This calibration results in a more precise older age of 28.201 +/- 0.046 million years ago (Ma) and reduces the 40Ar/39Ar method's absolute uncertainty from approximately 2.5 to 0.25%. In addition, this calibration provides tight constraints for the astronomical tuning of pre-Neogene successions, resulting in a mutually consistent age of approximately 65.95 Ma for the Cretaceous/Tertiary boundary.     

园林植物抗旱性研究进展

干旱是主要的环境胁迫因子之一,严重影响了植物的分布与生长发育,研究和探索植物的抗旱性已经成为众多研究者关注的焦点。从干旱胁迫下植物的形态结构特征、生长状况、生理生化反应等方面综述了园林植物抗旱性的研究进展,并在此基础上提出今后的研究重点。     

大豆抗原蛋白对草鱼肌肉营养成分的影响

以健康的初始体质量(50.66±0.26)g草鱼(Ctenopharyngodon idellus)为试验对象,在室内[(19±3)℃]单循环控温养殖系统中进行6周饲养试验,以鱼粉为对照组,β-伴大豆球蛋白的添加量为40 mg/g,大豆球蛋白的添加量为60 mg/g,配制成3种等氮(粗蛋白质量分数为30%)、等能(15.6 MJ/kg)的半精制饲料,探讨大豆主要抗原蛋白对草鱼肌肉主要营养成分的影响。结果表明:大豆主要抗原蛋白使草鱼肌肉中粗蛋白含量极显著下降(P0.01),对肌肉中水分、粗脂肪、粗灰分、氨基酸总量、必需氨基酸总量和鲜味氨基酸总量影响不显著(P0.05)。可见,在本试验条件下,草鱼配合饲料蛋白水平为30%时,在其配合饲料中分别添加β-伴大豆球蛋白(40 mg/g)和大豆球蛋白(60 mg/g)显著影响了草鱼肌肉中粗蛋白的含量。     

高吞吐量协作防火墙的双向去冗余方法

针对协作防火墙中冗余规则会降低其吞吐量的问题,提出一种基于双向去冗余的高吞吐量协作防火墙优化方法.该方法通过比对协作防火墙中双方的防火墙规则,双向去除域内防火墙之间的冗余规则,提高整个协作防火墙的数据包过滤能力.仿真实验结果表明,该方法的冗余率达到了22.7%,提高了8.2%吞吐量,明显优于已有协作防火墙优化方法.     

EVALUATION OF POTENTIAL SUBSTRATES TO MONITOR RESPIRATORY NITRATE REDUCTASE ACTIVITY IN SOILS

Different inorganic ions were tested for their ability to replace nitrate as the terminal oxidant for bacterial respiration in anaerobic soils. Chlorate, bromate. selenate. tellurite and ferric ions were all unsuitable substitutes, lodate reduction in soils was similar to nitrate reduction because it required anaerobic conditions, was increased by glucose amendment and decreased by phenylmercuric acetate. Amendment of soils with iodate and measurement of iodide production can be used to measure nitrate reductase activity in a soil and so give a qualitative indication, and possibly a quantitative estimate, of the denitrification capacity of soils.     

Immunohistochemical study on changes in gill Na+/K+-ATPase α-subunit during smoltification in the wild masu salmon, Oncorhynchus masou

Changes in immunoreactivity of Na⁺/K⁺-ATPase -subunit in gill sections of wild masu salmon (Oncorhynchus masou) during the parr-smolt transformation (smoltification) were compared with changes in gill Na⁺/K⁺-ATPase specific activity. Gill Na⁺/K⁺-ATPase specific activity increased from April and peaked in May. Immunohistochemical analysis, using an antiserum against a synthetic oligopeptide based on the conserved region of the Na⁺/K⁺-ATPase -subunit, revealed that immunoreactivity was confined to chloride cells in the surface layer of primary lamellae and the proximal end of secondary lamellae. The size and number of these cells increased gradually from February to May; however, the number of chloride cells of the secondary lamellae decreased in May. These data suggest that the synthesis of Na⁺/K⁺-ATPase and the proliferation of chloride cells occur prior to the elevation of enzyme activity. Moreover, it is likely the proliferation and hypertrophy of chloride cells on primary lamellae prepare smolts for entry into seawater and migration in the ocean.     

Insulin and IGF-I receptors and tyrosine kinase activity in carp ovaries: changes with reproductive cycle

Insulin and insulin-like growth factor I (IGF-I) receptors from carp ovaries were semipurified with wheat germ agglutinin at different moments of the reproductive cycle and their binding characteristics and tyrosine kinase activity were studied. Specific receptors for insulin and IGF-I were found. IGF-I receptors presented higher binding (23.8 ± 1.5%), number of receptors (965 ± 20fm/mg) and affinity (K_D 0.24 ± 0.03nM) than those shown for insulin receptors (4.1 ± 1%, 530 ± 85fm/mg and 0.85 ± 0.1nM, respectively). Insulin and IGF-I receptors have a tyrosine kinase activity which is not different from that found in muscle of the same species. Seasonal changes were found in binding, with maximum values for insulin and IGF-I reached at the end of pre-spawning period (June). However, while IGF-I binding was observed in all stages, insulin binding decreased in autumn and disappeared in winter, which suggests a different role for the two peptides in ovarian physiology.     

Development and characterization of a cell line TTCF from endangered mahseer Tor tor (Ham.)

Tor tor is an important game and food fish of India with a distribution throughout Asia from the trans-Himalayan region to the Mekong River basin to Malaysia, Pakistan, Bangladesh and Indonesia. A new cell line named TTCF was developed from the caudal fin of T. tor for the first time. The cell line was optimally maintained at 28°C in Leibovitz-15 (L-15) medium supplemented with 20% fetal bovine serum (FBS). The propagation of TTCF cells showed a high plating efficiency of 63.00%. The cytogenetic analysis revealed a diploid count of 100 chromosomes at passage 15, 30, 45 and 60 passages. The viability of the TTCF cell line was found to be 72% after 6 months of cryopreservation in liquid nitrogen (-196°C). The origin of the cell lines was confirmed by the amplification of 578- and 655-bp sequences of 16S rRNA and cytochrome oxidase subunit I (COI) genes of mitochondrial DNA (mtDNA) respectively. TTCF cells were successfully transfected with green fluorescent protein (GFP) reporter plasmids. Further, immunocytochemistry studies confirm its fibroblastic morphology of cells. Genotoxicity assessment of H?O? in TTCF cell line revealed the utility of TTCF cell line as in vitro model for aquatic toxicological studies.     

Fish-based methods for assessing European running waters: a synthesis

Abstract  The European Union, Water Framework Directive (WFD) requires monitoring of riverine fish fauna. When the WFD came into force in 2000, most of the EU member states did not have fish-based assessment methods compliant to WFD requirements. Therefore, the objectives of FAME ( http://fame.boku.ac.at ), a project under the fifth R&D Framework Programme of the European Commission were to develop, evaluate and implement a standardised fish-based method for assessing the ecological status of European running waters. This paper synthesises the outputs of FAME and defines future research needs. Two different methodologies were used: the so-called spatially based modelling and the site-specific modelling, the latter leading to the European Fish Index (EFI). The advantage of the EFI is that, despite being a single index, it is applicable to a wide range of environmental conditions across Europe precluding the need for inter-calibration. The EFI will support the WFD towards harmonised/standardised assessment and management of running waters in Europe, thus enabling comparative analyses of the ecological status of running waters across Europe.     

An investigation into the bacterial aetiology of 'black patch necrosis' in Dover sole, Solea solea L.

Abstract. A recurring disease known as 'black patch necrosis' (BPN) has been the cause of severe mortalities in 0-group and 1-group Dover sole during the period 1974-1978 at the Sea Fish Industry Authority's Marine Cultivation Unit at Hunter-ston, Ayrshire, Scotland. Samples of diseased and healthy Dover sole tissue were examined microbiologically and a long thin filamentous Gram-negative organism, strongly resembling Flexibacter columnar's , was repeatedly isolated from diseased tissue but was not found in healthy tissue. This organism was pathogenic to Dover sole, producing 100% mortality in 96 h at 17.5°C (±2°C) and the organism was reisolated from all the infected fish. The pathogenic isolate and reisolate were examined and compared with reference strain NCMB 1038 of Flexibacter columnarts , formerly known as Chondrococcus columnaris or Cytophaga columnaris. The isolate, reisolate and type culture were identical with respect to cell morphology, oxidase test, catalase production, production of H₂S, casein hydrolysis, gelatin liquefaction, hydrolysis of Tween 20, degradation of tyrosine and starch hydrolysis. All bacterial types showed similar patterns of sensitivity to a range of antibiotics. It is proposed that a Flexibacter columnari's-like organism is associated with the condition in farmed Dover sole known as 'black patch necrosis'.