Cryopreservation of mantle dissociated cells from Haliotis tuberculata (Gastropoda) and postthawed primary cell cultures

Dissociated mantle cells from the gastropod mollusc Haliotis tuberculata were cultured after a freezing-thawing procedure using either 10% dimethyl sulfoxide (Me(2)SO) or 10% glycerol (Gly) as a cryoprotector. The survival rate of 2-day-old cultured cryopreserved cells after thawing, based on analysis of DNA and protein contents, was nearly 80% in comparison with 2-day-old cultured fresh cells. Cells thawed after cryopreservation exhibited the maintenance of all tested physiological activities. Metabolic activity (measured by the MTT test) and the activity of alkaline phosphatase (a plasma membrane-bound enzyme) were not decreased in comparison to those in cultured fresh cells. In addition, cryopreserved cultured cells maintained a physiological stimulation ability in response to treatment with growth factors. These results taken together represent one of the most convincing demonstrations of the survival and of the recovery of intact functional activities of molluscan cells after a freeze-thawing procedure. Our results suggest that in the future primary cultures of cryopreserved mantle cells will be able to be used for fundamental research, in toxicity tests, or in the field of biotechnology.     

广东上川岛潮间带软体动物的分布

对上川岛潮间带软体动物进行了采集调查,共鉴定软体动物172种,分属53科。其中瓣鳃纲20科81种,占总数47．09％,腹足纲33科91种,占总数52．91％。分析表明,其区系特点是以南海亚热带-热带种和东海、南海亚热带种为主要成分。     

Sarcoplasmic reticulum in the cross-striated adductor muscle of the bay scallop,Aequipecten irridians

Summary The fine structure of the striated adductor muscle of the bay scallop, Aequipecten irridians has been investigated with particular emphasis on the sarcoplasmic reticulum. Each cell of the muscle contains a single myofibril. There is no transverse tubular system in this muscle. The cisternae of the sarcoplasmic reticulum are all interconnected by means of tubular elements. This extensive, interconnected system of flattened cisternae and tubular vesicles is distributed randomly with respect to the sarcomere and is in close association with the sarcolemma.     

Release of proteins and polysaccharides from the albumen gland of the freshwater snail Helisoma duryi : effect of cAMP and brain extracts

The albumen gland is a compound tubular exocrine gland found in the female reproductive tract of freshwater pulmonate snails such as Helisoma duryi. It secretes a perivitelline fluid, composed of protein and polysaccharide complexes, and coats each fertilized egg. A 288-kDa native glycoprotein, composed of several 66-kDa subunits, was identified in soluble extracts of albumen gland. Forskolin stimulates the release of secretory granules, containing both proteins and polysaccharides, from the cytoplasm of the glandular cells. An acid extract of the central nervous system or the adenosine-3′,5′-cyclic monophosphate (cAMP) analogue 8-bromo cAMP, stimulates protein secretion from the gland. Pretreatment of the albumen gland with cAMP antagonist (R_p isomer of cAMP) inhibits the stimulatory effect of a brain extract. Digestion of brain extract with proteolytic enzymes abolishes its activity, suggesting the factor from the brain is peptidergic. The neuroactive agents serotonin, Phe-Met-Arg-Phe-amide, Tyr-Gly-Gly-Phe-Met-Arg-Phe-amide, small cardioactive peptide B, and caudodorsal cell hormone were also tested for potential secretion-promoting ability. Brain extracts were partially purified with a Sep-Pak C₁₈ reverse-phase cartridge and indicate the peptide is relatively hydrophobic. These results suggest that a brain peptide promotes the secretion of perivitelline fluid, and this is mediated by the adenylate cyclase/cAMP signal transduction pathway. Accepted: 19 December 1997     

Elemental distribution in cephalopod statoliths: NanoSIMS provides new insights into nano-scale structure

We have applied the novel analytical method NanoSIMS to cephalopod statoliths for the first time in order to analyse their chemical microstructure, using a spatial resolution of 400 nm. This technique makes it possible to analyse in situ nano-scale chemical variations between increment layers. In statoliths of the boreoatlantic armhook squid Gonatus fabricii, we found distinct concentration patterns indicating a periodicity in strontium and sodium distributions. Sr and Na show a negative relation, both elements showing alternating patterns where the increments vary in width between approximately 1 and 5 μm. Results suggest, that aragonite deposited during the night is rich in Na and poor in Sr, while aragonite deposited during the day is rich in Sr and poor in Na. This study demonstrates the excellent suitability of NanoSIMS for nano-scale microchemical analyses of aragonite, providing new information on calcification processes and individual life histories. Possible future fields of application include not only cephalopod statoliths, but also virtually all biomineralized tissues in aquatic organisms like fish otoliths, gastropod statoliths, bivalve shells, foraminifers and corals.     

Molecular Dynamics Simulations for Metallic Nanosystems

Nanotechnology is a crucial field for future scientific development where many different disciplines meet. Computational modelization of nanometer-sized structures is a key issue in this development because (i) it allows a considerable saving of resources and costly experimental setups intended to fabricate nanometric test devices and (ii) nowadays the study of nanometric sized systems is feasible with thoroughly designed computational codes and relatively low cost computational resources. This article describes how molecular dynamics simulations, in combination with potentials obtained in the framework of the embedded atom method, are able to describe the properties of two systems of interest for the development of future nanoelectronic devices: metallic nanowires and metallic nanofilms. Our results show that nanowire stretching results in a series of well-defined geometric structures (shells) and that thin films experiment a crystallographic phase transition for a decreasing number of layers. In both cases, good agreement with experiments is found.     

SPRING – An image processing package for single-particle based helical reconstruction from electron cryomicrographs

Helical reconstruction from electron cryomicrographs has become a routine technique for macromolecular structure determination of helical assemblies since the first days of Fourier-based three-dimensional image reconstruction. In the past decade, the single-particle technique has had an important impact on the advancement of helical reconstruction. Here, we present the software package SPRING that combines Fourier based symmetry analysis and real-space helical processing into a single workflow. One of the most time-consuming steps in helical reconstruction is the determination of the initial symmetry parameters. First, we propose a class-based helical reconstruction approach that enables the simultaneous exploration and evaluation of many symmetry combinations at low resolution. Second, multiple symmetry solutions can be further assessed and refined by single-particle based helical reconstruction using the correlation of simulated and experimental power spectra. Finally, the 3D structure can be determined to high resolution. In order to validate the procedure, we use the reference specimen Tobacco Mosaic Virus (TMV). After refinement of the helical symmetry, a total of 50,000 asymmetric units from two micrographs are sufficient to reconstruct a subnanometer 3D structure of TMV at 6.4 Å resolution. Furthermore, we introduce the individual programs of the software and discuss enhancements of the helical reconstruction workflow. Thanks to its user-friendly interface and documentation, SPRING can be utilized by the novice as well as the expert user. In addition to the study of well-ordered helical structures, the development of a streamlined workflow for single-particle based helical reconstruction opens new possibilities to analyze specimens that are heterogeneous in symmetries.     

Mollusc and plant assemblages controlled by different ecological gradients at Eastern European fens

Ecological patterns of mollusc assemblages and vegetation in relation to water chemistry, water regime, nutrient availability and climate were studied in eastern Polish lowland fens. Our goal was to examine if major compositional changes differ for molluscs and vegetation under the joint influence of multiple ecological gradients. Altogether 32 fen sites were investigated in 2010–2011, and analyzed using metric multidimensional scaling, cluster analysis and generalized additive models. Two major gradients driving the differences in mollusc species composition were revealed. The main direction of compositional changes was associated with the water table gradient, governing a species turnover from inundated and strongly water-logged sites occupied mostly by aquatic mollusc species, to moderately wet sites with the predominance of fen and meadow species. The second most important gradient for molluscs was that of mineral richness. For vegetation, three major gradients explained the changes in species composition. The highest importance was assigned to the nitrogen-to-phosphorus availability gradient (defined as a shift from N-limited to P-limited vegetation), followed by the water table gradient, and the mineral richness gradient. Our results demonstrate that the impact of mineral richness gradient, which has been often reported as the major determinant of compositional changes of fen molluscs and vegetation, can be exceeded by other ecological gradients of comparable variation. We also document for the first time that the main species turnover of fen vegetation is not accompanied by the analogous change in species composition of mollusc assemblages, due to a different sensitivity of these taxa to particular environmental factors (i.e. water level dynamics and type of nutrient limitation).     

Evidence of formation of glushinskite as a biomineral in a Cactaceae species

The X-ray diffractometric and infrared spectroscopic investigation of crystalline material isolated from the Cactaceae species Opuntia ellisiana shows the presence of a very complex mineral composition, including whewellite (monohydrated calcium oxalate), opal (SiO2), calcite (CaCO3) and glushinskite (dihydrated magnesium oxalate). This is the first report of the presence of magnesium oxalate in plants.     

Secretory tissues in the East African shrubby aloes

Examination of Aloe leaf sections revealed the presence of three types of cells at the phloem pole of the vascular bundles, aloin cells, outer bundle sheath cells and fibres. Three species contain fibres alone and produce a sparse exudate with few components staining purple with Fast Blue B on thin-layer chromatograms. The majority of species have aloin cells of various sizes and in the tetraploid species these produce a copious exudate containing anthraquinone and chromone derivatives. It is suggested that the aloin cells act as storage tissue and that the compounds are synthesized in the surrounding layer of cells of smaller diameter, many of which can be seen to contain globules of unknown constitution. Anatomical observations support the idea that the shrubby tetraploid Aloe species are derived from a form similar to the diploid Aloe morijensis. Two forms of this species have been described, one with fibres only and few exudate components and another with both fibres and aloin cells and an exudate containing compounds of the tetraploid species. A line of diploid plants similar in anatomy and chemistry to the first form is represented by A. fibrosa and A. babatiensis while a line of tetraploids with affinities to the second form is represented by A. nyeriensis, A. cheranganiensis, A. elgonica, A. dawei and A.yavellana.     

Molluscan twitchin can control actin-myosin interaction during ATPase cycle

The effect of twitchin, a thick filament protein of molluscan muscles, on actin-myosin interaction at several mimicked sequential steps of the ATPase cycle was investigated using fluorescent probes specifically bound to Cys707 of myosin subfragment-1 and Cys374 of actin incorporated into ghost muscle fibers. The multi-step changes in mobility and spatial arrangement of myosin SH1 helix and actin subdomain-1 during the ATPase cycle have been revealed. For the first time, the inhibition of movement of myosin SH1 helix and actin subdomain-1 during the ATPase cycle and the decrease in the myosin head and actin affinity in the presence of unphosphorylated twitchin have been demonstrated. Phosphorylation of twitchin by the catalytic subunit of protein kinase A reversed this effect. These data imply a novel property of twitchin consisting in its ability to regulate in a phosphorylation-dependent manner the actin-myosin interaction during the ATPase cycle by the inhibition of transformation of the weak-binding actomyosin states into the strong-binding ones.     

The arrangement of neurosecretory and catecholamine fibres in relation to the pituitary intermedia cells of the skate,Raja radiata

Summary The innervation pattern of the intermediate lobe of the skate (Raja radiata) was studied with histological and fluorescence histochemical methods. Neurosecretory fibres, stained with i.a. pseudo-iso-cyanine, were found running in bundles in the central parts of the cell cords. They terminated partly around the perinuclear parts of the intermedia cells, partly around the apices of the cells close to the vascular walls.A catecholamine innervation of the intermedia was also established. Catecholaminecontaining fibres with the appearance of nerve terminals were found around the intermedia cell apices close to the vessels. In some specimens, catecholamine fibres also seemed to terminate at the perinuclear parts of the cells.Thus it is possible, judging solely from structural relations, that both the cell body (the synthesis pole) and the cell apex (the release pole) receive a dual innervation. Recent experimental evidence indicates that the release of MSH from the pars intermedia is controlled by catecholamine fibres, but as yet there is only structural evidence for a special control of hormone synthesis.This study was supported by grants from the Swedish Natural Science Research Council (No. 99-35 and 2126-2) and was carried out within a research organization sponsored by the Swedish Medical Research Council (Projects No. B70-14X-712-05 and B70-14X-56-06).     

螺旋CT三期扫描在肝癌诊断中的价值

目的：探讨肝癌螺旋CT多期扫描影像特征和临床应用价值.方法：对诊断为肝癌的83例患者先行全肝CT平扫,其中73例不论肿瘤大小（包括21例结节型）先作病灶动脉期扫描,再作全肝静脉期扫描,最后进行病灶平衡期扫描.10例仅行动脉期及静脉期扫描.结果：83例中57例为巨块型（68.67%）,16例为结节型（19.27%）,10例为弥漫型（12.04%）.73例中CT平扫、动脉期、静脉期及平衡期病灶的显示率分别为89%、98%、92%、98%.结论：螺旋多期扫描能获得肿瘤在各期增强征象,为肝癌的定性定量诊断提供更多的影像诊断信息;尤其在早期肝癌诊断,动脉期扫描可得到非常重要的诊断依据.     

多排螺旋CT后处理技术对不规则骨骨折的诊断价值

目的:探讨多排螺旋CT及其后处理技术在诊断不规则骨骨折中的诊断价值。方法:用16排螺旋CT对25例怀疑颅骨、脊柱或关节附近骨折的外伤患儿进行扫描并进行后处理(MPR、VR)。结果:25例病例中颅骨骨折15例,脊柱骨折5例,四肢关节骨折5例(其中3例关节内骨折伴有骺软骨损伤)。结论:对于不规则骨骨折,多排螺旋CT及其后处理重建具有很大的优越性,应横断位、MPR及VR三者相结合判断,为临床提供丰富的、科学的、准确的信息依据。