Fertilization-Induced changes in the vitelline envelope of echinoderm and amphibian eggs: Self-assembly of an extracellular matrix

The surface of the unfertilized sea urchin egg is covered by the vitelline layer (VL), a fibrous extracellular matrix that contains receptors for sperm. At fertilization, cortical granule exocytosis releases enzymes and structural proteins that cause the VL to elevate and become remodelled into the mechanically and chemically tough fertilization envelope. This envelope prevents further penetration of sperm and protects the embryo during early development. A thicker, more complex vitelline envelope surrounds the Xenopus laevis egg. This fibrous coat is also restructured at fertilization to produce an impenetrable barrier to sperm. The biochemical steps that occur during self-assembly of these fertilization envelopes are reviewed, and the ultrastructural changes that occur, as seen in platinum replicas of quick-frozen, deep-etched, and rotaryshadowed eggs, are illustrated.     

Gamete interactions and the fate of sperm organelles in fertilized echinoderm eggs

Investigations of gamete fusion, sperm entry and the fate of the sperm nucleus, plasma membrane, mitochondrion, and axonemal complex in fertilized echinoderm eggs are reviewed. The timing of gamete fusion with respect to the onset of electrical activity characteristic of the activated egg and the affects of fixation conditions on the stability of fusing membranes are discussed. Observations from investigations using cationized ferritin labeled gametes and immunogold cytochemistry to demonstrate the mixing of sperm plasma membrane components within the egg plasma membrane, in particular along the surface of the fertilization cone, are compared with results from studies in somatic cells. Transformations of the sperm nucleus into a male pronucleus, consisting of sperm nuclear envelope breakdown, chromatin dispersion, and formation of a pronuclear envelope, are correlated with recent biochemical observation of similar processes in other cellular systems. Fates of the sperm mitochondrion and axonemal complex are examined.     

HVAF-ARC喷涂Cr2C3活性功能涂层性能的研究

本文采用HYAF-ARC喷涂系统制造的NiCrFe-Cr2C3活性功能涂层。通过金相组织研究、SEM检测．X射线衍射以及涂层结合强度分析．证明其具有良好的组织形貌;同时HVAF-ARC所制备的Cr2C3合金除层的性能相对于普通电弧喷涂涂层的性能在同等试验条件下优于普通高速电弧喷涂。     

Preservation and visualization of the sea urchin embryo blastocoelic extracellular matrix.

Several methods were utilized to visualize the structure and orientation of the blastocoelic extracellular matrix (ECM) in Strongylocentrotus purpuratus embryos at the mesenchyme blastula stage. Rapid freezing in liquid propane cooled to LN2 temperatures followed by freeze substitution was used to preserve the ECM without shrinkage due to dehydration. Scanning, transmission, and light microscopy were employed to elucidate the ECMs' structure. The blastocoelic ECM consisted of parallel fibrillar sheets that were interconnected by finer filaments and oriented along the animal-vegetal axis. The ECM completely filled the blastocoelic cavity as viewed by scanning electron microscopy. The basal lamina could be distinguished from the blastocoelic ECM as a thin coat on the plasma membrane of epithelial cells; the ECM was in contact with this coat. In contrast, the blastocoelic ECM attached directly to the plasma membrane of primary mesenchyme cells (PMC) which did not possess a basal lamina. The blastocoelic ECM was isolated as an intact "bag" and probed in a hydrated state with Con A and alcian blue. Confocal microscopy confirmed that the entire blastocoel was filled with a fibrillar ECM. These approaches offer advantages for future studies of the ECMs of sea urchin embryos and their roles in gastrulation.     

一种简明易用的结构优化的包络函数

利用包络函数可以使数目庞大的多个约束转化为一个约束或少数几个约束,目前流行的是K-S熵包络函数。介 绍K-R.M.S.均方根包络函数,与熵包络函数相比,这种包络函教具有表达简捷、意义明确、方便易用的优点。     

Biochemical and morphological alterations of the extracellular matrix of chicken calcaneal tendon during maturation

The region in tendons that surrounds bone extremities adapts to compression forces, developing a fibrocartilaginous structure. During maturation, changes occur in the amount and organization of macromolecules of the extracellular matrix of tendons, changing the tissue morphology. To study the effect of maturation on tendons, Pedrês chickens were sacrificed at 1, 5, and 8 months old and had the calcaneal tendon (CT) divided into proximal region, submitted to tension/compression forces ( p ), and distal region submitted to tension force ( d ). Morphological analysis of the p region showed the presence of fibrocartilage in all ages. In the central part of the fibrocartilage, near a diminishment of the metachromasy, there was also a development of a probable fat pad that increased with the maturation. The activity of MMP‐2 and MMP‐9 was higher at 5 and 8 months old, in both regions, compared with 1‐month‐old animals. In SDS‐PAGE analysis, components with electrophoretic migration similar to decorin and fibromodulin increased with maturation, particularly in the d region. The Western blotting confirmed the increased amount of fibromodulin with maturation. In conclusion, our results show that process of maturation leads to the appearance of a probable fat pad in the center of the fibrocartilage of CT, with a reduced amount of glycosaminoglycans and an increased activity of MMPs. Microsc. Res. Tech. 78:949–957, 2015. © 2015 Wiley Periodicals, Inc.     

Possible roles of extracellular matrix and cytoskeleton in leech body wall muscles

Round circomyarian fibres of leeches are peculiar helical muscles. The fibres are characterized by a lack of junctions, being separated by a thick extracellular matrix, and by scarce end-plates. Even so, the fibres grouped in units show the same degree of contraction. Biochemical, immunocytochemical and ultrastructural studies were performed in order: (a) to demonstrate the presence in the extracellular matrix of fibronectin, collagen type IV and laminin and in the cytoskeleton of desmin and α-actinin; (b) to show the possible link of extracellular matrix with the scaffold of intermediate filaments; (c) to evaluate how the extracellular matrix can play a role in the transduction of a signal during contraction–relaxation–superelongation phases.     

A method for TEM visualization of the extracellular matrix three-dimensional organization in tissues

A method for obtaining high-resolution three-dimensional images of the extracellular matrix organization in tissues is described. It consists of TEM observation of rotary-shadowed platinum–carbon replicas obtained from critical-point dried resinless sections of polyethylene glycol-embedded specimens. The procedure is simple and rapid, with high rates of sample recovery. An example of its application to EM immunocytochemistry (fibronectin localization) is presented. The utilization of the method to demonstrate cell-extracellular matrix relationships, and its limitations in the study of cells are discussed.     

Microscopical evaluation of extracellular matrix and its relation to the palatopharyngeal muscle in obstructive sleep apnea

Obstructive sleep apnea hypopnea syndrome (SAHS) is a complex disease of the upper respiratory airways. SAHS physiopathology is multifactorial in which airway compliance is a very important component. To evaluate the tissue changes in the palatopharyngeal muscle by morphometric, histochemical, immunohistochemical, and stereological quantification, with special attention to extracellular matrix associated with this muscle at the structural and ultrastructural levels. Thirty patients with SAHS were divided into groups of 10 according to disease severity: mild, moderate, and severe SAHS. In addition, the control group consisted of 10 patients. Fragments of palatopharyngeal muscle removed from patients with SAHS and tonsillectomies from patients in the control group were histopathologically submitted to light microscopy and transmission electron microscopy. Histopathological evaluations by light and transmission electron microscopes showed differences in analyzed groups, such as reduction of the muscle fiber diameter in patients with SAHS, taking disease severity into consideration. In contrast, stereological analysis showed a gradual increase of the collagen and elastic system fibers relative frequencies, proportionally to SAHS seriousness. MMP‐2 and MMP‐9 immunostaining also showed an increased reaction in the muscle fiber cytoplasm and endomisium during SAHS progression. The ultrastructural analysis showed that palatopharyngeal muscle fibers presented cytoplasmic residual corpuscles, a sign of early cell aging. In conclusion, the increase of tissue compliance in individuals with SAHS can be, in addition to other factors, consequence of diminished contractile activity of the muscle fibers, which exhibited clear signs of early senescence. Moreover, extracellular matrix components changes may contribute to muscle myopathy during SAHS progression. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Structure and function of endothelial caveolae

Caveolae are spherical invaginations of the plasma membrane and associated vesicles that are found at high surface densities in most cells, endothelia included. Their structural framework has been shown to consist of oligomerized caveolin molecules interacting with cholesterol and sphingolipids. Caveolae have been involved in many cellular functions such as endocytosis, signal transduction, mechano-transduction, potocytosis, and cholesterol trafficking. Some confusion still persists in the field with respect to the relationship between caveolae and the lipid rafts, which have been involved in many of the above functions. In addition to all these, endothelial caveolae have been involved in capillary permeability by their participation in the process of transcytosis. This short review will focus on their structure and components, methods used to determine these components, and the role of caveolae in the transendothelial exchanges between blood plasma and the interstitial fluid.     

CCD辐射响应函数矩阵的建立与应用

为了能采用物理意义明确的函数式来表述大格式电荷耦合器件(CCD)的性能参数,直观地实现对面阵CCD辐射性能的评价,本文提出利用“辐射响应函数矩阵”概念来表述CCD每个像元的辐射性能参量.首先,分析了该矩阵各元素的物理意义,提出了对CCD每个像元的绝对辐射响应度、响应非线性度、暗噪声、信噪比以及非均匀性的描述方法.其次,对面阵CCD KAI-16000进行辐射性能检测,并利用回归分析计算出各像元的响应系数.最后,以测试结果为例,讨论和描述该矩阵的应用和结果.实验结果表明:该CCD近似成线性响应,通过矩阵函数可以计算出CCD非均匀性为3.1％,暗噪声为3.84.此方法实用,满足对大格式CCD直观表述的要求.     

Three-dimensional investigation and scoring of extracellular matrix remodeling during lung fibrosis using multiphoton microscopy

The organization of collagen during fibrotic processes is poorly characterized because of the lack of appropriate methodologies. Here we show that multimodal multiphoton microscopy provides novel insights into lung fibrosis. We characterize normal and fibrotic pulmonary tissue in the bleomycin model, and show that second-harmonic generation by fibrillar collagen reveals the micrometer-scale three-dimensional spatial distribution of the fibrosis. We find that combined two-photon excited fluorescence and second-harmonic imaging of unstained lung tissue allows separating the inflammatory and fibrotic steps in this pathology, underlining characteristic features of fibroblastic foci in human Idiopathic Pulmonary Fibrosis samples. Finally, we propose phenomenological scores of lung fibrosis and we show that they unambiguously sort out control and treated mice, with a better sensitivity and reproducibility in the subpleural region. These results should be readily generalized to other organs, as an accurate method to assess extracellular matrix remodeling during fibrosis.     

Structure and function of the bat superior olivary complex

The superior olivary complex (SOC) is a mammalian auditory brainstem structure that contains several nuclei. Some of them are part of the ascending system projecting to higher auditory centers, others belong to the descending system projecting to the cochlear nuclei or the cochlea itself. The main nuclei of the ascending system, the lateral and medial superior olive (LSO, MSO), as well as the lateral and medial nuclei of the trapezoid body (LNTB, MNTB), have been traditionally associated with sound localization. Here we review the results of recent studies on the main SOC nuclei in echolocating bats. These studies suggest that some SOC structures and functions are highly conserved across mammals (e.g., the LSO, which is associated with interaural intensity difference processing), while others are phylogenetically highly variable in both form and function (e.g., the MSO, traditionally associated with interaural time difference processing). For the MSO, these variations indicate that we should broaden our view regarding what functions the MSO might participate in, since its function in echolocation seems to lie in the context of pattern recognition rather than sound localization. Furthermore, across bat species, variations in the form and physiology of the MSO can be linked to specific behavioral adaptations associated with different echolocation strategies. Finally, the comparative approach, including auditory specialists such as bats, helps us to reach a more comprehensive view of the functional anatomy of auditory structures that are still poorly understood, like the nucleus of the central acoustic tract (NCAT).     

Use of membrane filters and osmium tetroxide etching in the preparation of sperm for scanning electron microscopy

A new method was developed which is suitable for the preparation of mammalian sperm for scanning electron microscopy under either laboratory or field conditions. Samples of ejaculates from humans, two ferret species, and epididymal sperm from the African elephant were diluted in Millonig phosphate buffer and then fixed in glutaraldehyde solution. A small sample of the fixed sperm suspension was diluted in the same buffer, withdrawn with a syringe, and injected very slowly onto either a cellulose acetate or a polycarbonate membrane filter. This step was essential to concentrate the dilute sperm samples. During the various dilution steps most of the granular prostatic secretions were lost. However, a protein-like sheath, which remained attached to most sperm, obscured the surface features and had to be removed for SEM studies. It was removed by prolonged fixation/etching in 1% osmium tetroxide. Membrane filters containing sperm on their surfaces then were dehydrated, dried by the critical point drying method, and sputter coated with gold. Polycarbonate filters were superior to cellulose acetate filters in producing a flat and homogeneous background.     

有效改善凸轮硬度和耐磨性的措施

介绍了几种能有效改善凸轮型面硬度和耐磨性的方法。凸轮磨损种类繁多,因根据具体情况选用适合的凸轮基材,并进行合理有效的热处理。合金涂层在不改变凸轮基材的情况下,能够有效提高凸轮的硬度和耐磨性。     

Structure and function of the yeast vacuole and its role in autophagy

The vacuole of the yeast Saccharomyces cerevisiae plays an important role in pH- and ion-homeostasis, and is used as a storage compartment for ions. Another important function of the vacuole, especially during nutrient limitation, is the bulk degradation of proteins and even whole organelles. To carry these proteins into the vacuolar lumen, sophisticated transport pathways have evolved. In this review, starvation-induced autophagy and its relationship to the specific cytoplasm to vacuole targeting (cvt-) pathway of proaminopeptidase I is discussed. A further topic is the specific vacuolar uptake and degradation of peroxisomes in Pichia pastoris cells via micro- and macroautophagy.     

CAD齿轮齿形生成及应用

以插入算法实现齿廓的电脑图形生成熏进一步设计成菜单命令。通过对输出齿形进行编辑分析熏为齿轮、滚刀设计提供直观的分析手段。     

Simulating gear and bearing interactions in the presence of faults: Part II: Simulation of the vibrations produced by extended bearing faults

This paper presents a combined dynamic model for gears and bearings, in which an extended fault in the inner/outer race of rolling element bearings can be studied in the presence of gear interaction. A combined gear/bearing model has been made to obtain a better understanding of the interaction of the two components. The essentials of the gear/bearing model and the results of simulating the vibration of localized faults in rolling element bearings in a gearbox environment have been discussed and illustrated in the first part of this paper (part I). The simulation model has now been modified to model extended faults of the type that do not necessarily produce high frequency impact responses, but do modulate the gearmesh signals. The paper compares the simulated and actual signals from the gear/bearing test rig for inner and outer race extended faults, and in particular demonstrates that they react similarly to existing diagnostic techniques.