Microstructure of pharyngeal tooth enameloid in the parrotfish Scarus rivulatus (Pisces: Scaridae)

The microstructure of parrotfish pharyngeal teeth was examined using scanning electron microscopy to infer possible mechanical properties of the dentition with respect to their function. Parrotfish tooth enameloid is formed from fluorapatite crystals grouped into bundles. In the upper and lower pharyngeal jaw, the majority of the crystal bundles are orientated either perpendicularly or vertically to the enameloid surface. The only exception is in the trailing apical enameloid in which the majority of bundles are orientated perpendicularly or horizontally to the trailing surface. A distinct transition occurs through the middle of the apex between the leading and trailing enameloid in teeth of the lower pharyngeal jaw. This transition appears less distinct in the teeth of the upper pharyngeal jaw. Enameloid microstructure indicates that shear forces predominate at the apex of the teeth. In the remainder of the enameloid, the microstructure indicates that wear is predominant, and the shear forces are of less importance.     

Irregular Shaped,Assumably Semi‐Crystalline Calciumphosphate Platelet Deposition at the Mineralization Front of Rabbit Femur Osteotomy: A HR‐TEM Study

Although bone minerals have been widely studied by various techniques in previous studies, crystal structures, morphology of bone minerals and its building pathway remained still controversy. In this work, the ultrastructure of the mineralization front of rabbit femur has been studied by conventional and high‐resolution (HR) transmission electron microscopy (TEM). In order to induce a healing and demineralization process the animals were subjected to a standardized osteotomy stabilized with titan screws and sonic pins. After 84 days follow‐up time the newly build bone was investigated. The mineralization front of rabbit femur osteotomy contains partly mineralized collagen fibrils with a pronounced striped pattern together with a large number of agglomerated apatite platelets. The striation is caused by mineralization in the hole zones of the collagen fibrils, corresponding to the early stage of mineralization. In the TEM micrographs, the mineralization zone appears denser and compact when compared with fully mineralized bone, although most of the collagen fibrils are completely mineralized in the latter (higher concentration of interfibrillar apatite platelets within the mineralization zone). In bone some partly mineralized collagen fibrils are also observed, revealing the same arrangement, regular shape, and size of apatite platelets as collagen fibrils in the mineralization zone. Apatite platelets with irregular shapes are observed at the vortex‐shaped outer boundary of the mineralization zone, i.e. at the interfaces with nonmineralized collagen or osteoblasts. HR TEM micrographs reveal that the platelets are assumably semicrystalline and that within the platelet nanocrystalline domains of apatite are embedded in an amorphous calciumphosphate matrix. SCANNING 35: 169‐182, 2013. © 2012 Wiley Periodicals, Inc.     

Zinc as an essential trace element in the acceleration of matrix vesicles-mediated mineral deposition

BACKGROUND: Zinc (Zn) has a potent stimulatory effect on osteoblastic bone formation and an inhibitory effect on osteoclastic bone resorption. PURPOSE: The effect of Zn on the function of matrix vesicles (MVs) remains controversial. The purpose of this study was to investigate the effect of Zn on alkaline phosphatase (ALP) activity of osteoblasts and in the initial biological MVs‐mediated mineral deposition. STUDY DESIGN: Osteoblasts were treated with varying concentrations of Zn dissolved in culture medium. After three, five, and seven days of culture, ALP activity was assayed. For the detection of a low level of calcium concentration in MVs, X‐ray fluorescence (XRF) analyses were applied. The effect of Zn for the transformation of calcium phosphate was analyzed using a scanning electron microscope fitted with an energy dispersive X‐ray microanalysis (EDX) system. RESULTS: The ALP activity of osteoblasts in culture medium supplemented with 1 × 10^?5M of Zn was significantly increased at both five and seven days. XRF data demonstrated higher levels of calcium concentration over time in the Zn‐supplemented group. EDX data showed that mineral deposits beginning on day 3 were transformed from whitlockite to calcium phosphate near hydroxyapatite, and that Zn accelerated this transformation. CONCLUSIONS: The proper concentration of Zn increased the ALP activity of osteoblasts after five and seven days of incubation. The present XRF and EDX data suggest that the increase of mineral deposition with Zn exposure for one to five days might be mediated by the activation of ALP and calcium‐binding proteins. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.     

Mineral-related proteins of sea urchin teeth: Lytechinus variegatus

Sea urchins have a set of five continuously growing teeth, each of which has a very complex structure. The mineral phase is calcite of varying Mg content, depending on the location within a tooth. The calcium carbonate is present in amorphous, plate-like and rod-like forms. It has been hypothesized that the mineral deposition is a matrix-mediated process, similar to that in vertebrate bone and tooth, wherein certain macromolecules within the organic matrix of the mineralized tissue play an important role in nucleating and controlling the growth habit of the mineral crystals. It has also been hypothesized that the mineral-related macromolecules involved in urchin teeth might bear a direct evolutionary relationship to those of the vertebrate tooth. These hypotheses are explored here by examining the pattern and nature of the mineral distribution, using microCT of intact teeth, and the nature of the mineral-related matrix proteins. The mineral-related proteins were extracted and fractionated by anion exchange chromatography. The relationship of certain fractions to vertebrate matrix proteins was established by immunoblots using antibodies to vertebrate tooth proteins. The antibodies were then used to localize the proteins within the teeth, by immunocytochemistry and histology with specific staining. The microCT data on mineral density has been correlated with the patterns of cellular migration and mineral deposition within the tooth as it grows. It appears that the mineralization within the different tooth compartments might take place under the influence of different matrix proteins. Further studies are in progress to more completely describe the vertebrate-invertebrate immunologically cross-reactive proteins of the urchin teeth.     

Early mineralization of matrix vesicles in the epiphyseal growth plate

Matrix vesicles (MVs) induce the primary mineralization in collagen-rich hard tissues such as bone, mineralizing cartilage and dentine. Calcium and phosphate ions accumulate at the inner MV membrane. This accumulation takes place in association with phospholipids alone and/or in association with Annexin V, which displays Ca ion channel activity when inserted in membranes; consequently, Annexin V may be involved in Ca uptake by matrix vesicles. The first crystal nuclei are formed at these macromolecules of the MV inner membrane. They grow to stable nanometre-sized particles, dots, which coalesce to form chains of dots along the macromolecules of the MV inner membrane. At the same time, or shortly afterwards, chains of these Ca phosphate dots also develop inside the MVs. The measured centre-to-centre distances between these dots represent approximately the distances between the nucleating sites, called active sites, along the MV matrix molecules. The mineralization does not stop at the MV membrane but expands continuously into the extravesicular region in radial directions to form nodules. These radiating Ca phosphate chains, which coalesce to form needles, are composed of such primary dots, which have developed at the nucleating sites of the corresponding macromolecules.     

Image analysis of electron micrographs relating to mineralization in calcifying cartilage: Theoretical considerations

Biological mineralization is a cell-mediated process which is believed to be triggered by a “nucleating agent.” Various matrix structures, such as matrix vesicles, collagen fibrils and macromolecules, have been claimed to be the source of this substance, since these components have been found by transmission electron microscopy (TEM) of thin sections to be associated with early mineral crystals. Systematic image analysis of the relationships revealed in electron micrographs between specific matrix components and early mineral deposits has shown that unequivocal image interpretation is not possible. This is due principally to the problems posed by overprojection and truncation phenomena, since the structures being analyzed lie within the same dimensional range as thin section thickness. Various examples are illustrated and discussed. The site at which mineral crystals are initially laid down thus cannot be identified with any matrix structure using thin section TEM. Possible technical approaches to resolve this problem of image analysis are discussed.     

Therapeutic application of mesenchymal stem cells-derived extracellular vesicles in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and the leading cause of cancer death globally. Resistance to therapy is a challenge for CRC treatment. Mesenchymal stem cells (MSCs) have become one of the furthermost effective approaches for tumor treatment due to their specific feature; however, their therapeutic function is controversial. Recently, extracellular vesicles (EVs) derived from MSCs (MSCs-EVs) have attracted extensive research attention due to their promising role in CRC treatment. EVs are cell-derived vesicles that transfer different biomolecules between cells, contributing to intracellular communication. MSCs-EVs can suppress CRC by delivering therapeutic agents to tumor cells. Several studies indicate that MSCs-EVs can serve as a drug delivery system for the treatment of different cancers. Various methods are used to modify (engineer) MSCs-EVs for loading therapeutic agents. Modified MSCs-EVs have improved specificity, targeting ability, and immunogenicity compared to synthetic carriers. Furthermore, CRC-EVs participate in regulating different cells, such as immune cells, fibroblasts, and endothelial cells, promoting tumorigenesis. MSCs-EVs-based therapy indicates a high potential in the treatment of cancer; however, the majority of studies have been conducted in the pre-clinical, and their clinical applications need further scrutiny. In this review, we describe the biogenesis of EVs, focusing on the effect of MSCs-EVs on CRC cells and CRC-derived EVs on other cells. Furthermore, MSCs-EVs as a drug delivery system for cancers is also reviewed, and perspectives regarding the therapeutic application of MSCs-EVs are discussed.     

鱼类干扰素系统的研究进展

干扰素系统是非特异性免疫系统的重要组成部分。干扰素作为先天性免疫系统的关键因子,在鱼类抵抗病毒感染中发挥了非常重要的作用。近年来,鱼类干扰素系统研究得到了迅速的发展。本文介绍了鱼类Ⅰ型和Ⅱ型干扰素及其受体、干扰素调节因子、JAK—STAT信号途径、干扰素诱导蛋白等的研究进展。     

鱼类干扰素系统的研究进展

干扰素系统是非特异性免疫系统的重要组成部分。干扰素作为先天性免疫系统的关键因子,在鱼类抵抗病毒感染中发挥了非常重要的作用。近年来,鱼类干扰素系统研究得到了迅速的发展。本文介绍了鱼类I型和II型干扰素及其受体、干扰素调节因子、JAK-STAT信号途径、干扰素诱导蛋白等的研究进展。     

The cytoskeleton in fish melanophore melanosome positioning

Melanophore melanosomes organelles can be regulated to move and locate correspondingly to many other different organelle types. Comparing lessons from analysis of a specific melanosome distribution can, therefore, contribute to the understanding of distribution of other organelles, and vice versa. From such data, it is now generally accepted that microtubules provide directed long-distance movement, while cell peripheral movements include microfilaments. In fish melanophores, both actin and dynein exhibit counter-forces to the kinesin-like protein in maintaining the evenly dispersed state, while actin and kinesin exhibit counter-forces to dynein in many other systems. Lessons from elevating cAMP levels indicate the presence of a peripheral feedback regulatory system involved in maintaining the evenly dispersed state. Studies from dynein inhibition suggest that the kinesin-like protein involved in fish melanosome dispersal is regulated in contrast to many other systems. One would further expect melanosome transport to be regulated also on actin/myosin, in order to prevent actin-dependent capture of melanosomes during the microtubule-dependent aggregation and dispersion. General findings will be discussed in comparison with positioning and movement of other organelle types in cells. Finally, recent data on melanosome-dependent organising of microtubules show that dynein is involved in nucleating microtubules extending from melanosome aggregates in melanophore fragments.     

Quantitative backscattered electron imaging of bone in proximal femur fragility fracture and medical illness

Bone quality consists of a number of factors including the amount of bone, bone architecture and the degree of bone mineralization. Quantitative backscattered electron imaging is a technique that allows the degree of mineralization of trabeculae to be assessed and in this study is applied to inter‐trochanteric bone biopsies of the proximal femur. Biopsy cores from 22 controls, nine individuals with acute and chronic medical conditions and 22 fragility fracture individuals undergoing total hip replacement were processed into methyl methacrylate, polished and analysed in a Philips XL20 scanning electron microscope. A mean and distribution of weight percent calcium were determined for each individual, and for the control, medically ill and fragility fracture groups. All individuals and groups of individuals showed normal distributions of percent calcium with both the ill and fragility fracture groups being under mineralized relative to the control group. The shape and position of the mineralization distributions suggest that the fragility group resulted from increased bone turnover with a slow progression to under mineralization. In contrast, the ill group appears to have had a more rapid change in the mineralization dynamic. Clear distinctions between the control, fragility fracture and medically ill groups could be seen when the mineralization data were plotted as a scatter graph against age. Graphing the data in this way showed an age‐related increase in the degree of mineralization in control individuals with the under‐mineralized, fragility fracture group scattered below this normal trend. The medically ill group was similarly less mineralized which highlighted the degree to which medical conditions and treatments can alter bone matrix mineralization.     

Analysis of tumor-draining vein secretome: A direct access to tumor-derived extracellular vesicles in surgical lung cancer patients

Tumor-secreted extracellular vesicles (EVs) participate in the metastasis process through different mechanisms, including the preparation of the pre-metastatic niche to grant circulating tumor cells (CTCs) implantation and growth. The study of the metastasis process through the analysis of CTCs and tumor-derived EVs is difficult because of the dilution grade of these elements in peripheral blood. In early-stage lung cancer patients, the tumor-secreted products are even more diluted. An attractive strategy in surgical lung cancer patients is to purify them from a pulmonary tumor-draining vein where they are enriched. The information obtained from the analysis of EVs and CTCs purified from this source could give more accurate information about tumor biology and could be an important source of biomarkers to identify patients at high risk of relapse after curative surgery.     

鱼类淋巴囊肿病的研究进展

鱼类淋巴囊肿病是一种慢性病毒性疾病,可以感染100种以上的温水域和低温水域的海、淡水鱼类,给水产养殖业造成了巨大的经济损失。文章综述了近年来鱼类淋巴囊肿病的研究现状,重点介绍了鱼类淋巴囊肿病的病原、传播途径、发病机理、诊断和防治等方面的研究进展,并对今后鱼类淋巴囊肿病的研究趋势进行了展望。     

石墨炉原子吸收法测定鱼肉中的铅

结合微波消解石墨炉原子吸收法测定鱼肉中的铅,快速、高效,结果令人满意。     

Fluorescence microscopy study on the cytoskeletal displacements during sperm differentiation in the bush‐cricket Tylopsis liliifolia (Fabricius) (Orthoptera: Tettigoniidae)

A study by fluorescence microscopy has been carried out on male gametes from testicular follicles, seminal vesicles, spermatophores, and seminal receptacles of the bush‐cricket Tylopsis liliifolia, focusing the attention on localization and movements of F‐actin and α‐tubulin during sperm differentiation, since data in this respect are lacking in the Orthoptera. F‐actin and α‐tubulin positivity was detected in the testicular follicles, in particular at the bridges connecting spermatids of a same clone and around their nucleus, during the first differentiation stages. During the following differentiation stages in the testes, F‐actin was found at one of the spermatid poles and then, during nucleus elongation, at the whole acrosomal region. A peculiar F‐actin‐positivity was found at the flagellum, more markedly immediately posterior to the nucleus, at the basal body region of the gametes from the testicular follicles and from the other examined districts. Other interesting data from our investigations concerns the α‐tubulin displacements during the differentiation stages of the spermatid and a constant absence of α‐tubulin‐positivity where the centrioles are located. No positivity was also found for both α‐tubulin and nuclear markers at the anterior region of the gamete, where the acrosomal wings are localized. Our results, compared with what is so far known in literature for the insects, lead us to assert that microfilaments and microtubules undergo gradual displacements, markedly in the testicular follicles, during the morphogenesis of the male gamete of T. liliifolia aimed to its organization and motility and probably also to its interaction with the female gamete. Microsc. Res. Tech. 79:81–88, 2016. © 2015 Wiley Periodicals, Inc.     

Proteomics in gram-negative bacterial outer membrane vesicles

Gram-negative bacteria constitutively secrete outer membrane vesicles (OMVs) into the extracellular milieu. Recent research in this area has revealed that OMVs may act as intercellular communicasomes in polyspecies communities by enhancing bacterial survival and pathogenesis in hosts. However, the mechanisms of vesicle formation and the pathophysiological roles of OMVs have not been clearly defined. While it is obvious that mass spectrometry-based proteomics offers great opportunities for improving our knowledge of bacterial OMVs, limited proteomic data are available for OMVs. The present review aims to give an overview of the previous biochemical, biological, and proteomic studies in the emerging field of bacterial OMVs, and to give future directions for high-throughput and comparative proteomic studies of OMVs that originate from diverse Gram-negative bacteria under various environmental conditions. This article will hopefully stimulate further efforts to construct a comprehensive proteome database of bacterial OMVs that will help us not only to elucidate the biogenesis and functions of OMVs but also to develop diagnostic tools, vaccines, and antibiotics effective against pathogenic bacteria.     

工厂化鱼类养殖池监测系统的开发

水质参数监测是工厂化水产养殖的重要组成部分,是工厂化养殖向自动化、大规模、高产量和高质量发展的关键环节。针对我国工厂化养殖水质监测手段落后、自动化水平低的现状,研制了一套适合国情的在线多参数水质监测系统,可对水温、水位、酸碱度（PH值）、溶解氧含量4个水质参数进行连续在线监测。以一台PC工业控制计算机作为现场上位机,以多台单片机作为现场鱼池的下位机,一旦发生故障,养殖池发生环境变化,能够及时报警,从而实现了对养殖现场中鱼类生长的实时监控。实际应用结果表明,系统运行稳定、安全可靠,测量数据的精确度完全可以达到工厂化渔业生产的要求。     

GIS中几种数据管理方式的比较

GIS系统的数据有其独有的特点,如何根据这些特点和不同的需求选择适当的数据管理方式,是关系着一个GIS系统成败的问题。本文阐述了几种数据管理方式,比较了每种方式相对的优缺点,得出在不同的场合中选择何种方式的结论。