中华鲟授精过程扫描电镜观察

在扫描电镜下观察到:中华鲟的成熟卵具有一层放射膜,两层卵黄膜;卵的动物极端有9—15个受精孔,受精孔直径约为12.7—13.9μm;精子由伞状顶体、棍棒状头部、漏斗状中段及扁平细长的尾部组成;各受精孔都能接纳多个精子;卵受精5秒后,精子才开始入卵,且精子入卵速度各不相同。受精时间持续较长,可由5秒延长至5分钟;卵受梢后,受精管道内除缠绕成团的精子尾部外,未发现其他堵塞物。     

Confocal Raman microspectroscopy on excised human skin: uncertainties in depth profiling and mathematical correction applied to dermatological drug permeation

Confocal Raman microspectroscopy represents the advantage of giving structural and conformational information on samples without any destructive treatment. Recently, several studies were achieved to study the skin hydration, endogenous and exogenous molecules repartition in the skin using the confocal feature of this technique. Meanwhile, when working through a material boundary with a different refractive index, the main limitation remains the spatial precision, especially the distortion in the depth and the depth resolution. Recently, several authors described mathematical models to correct the depth and the resolution values. In this study, we combined theoretical approaches, proposed by different authors with experimental measurements to try to find out the most appropriate approach for correction. We then applied the corrections on in‐depth profiles tracking the penetration of Metronidazole, a drug produced by Galderma for rosacea treatment, through excised human skin. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The neuromuscular system of the cyclostome bryozoan Crisia eburnea (Linnaeus, 1758)

The cyclostome bryozoans constitute an old and divergent group of bryozoans, whose muscle and nervous systems are poorly known. The entire neuromuscular system of the cyclostome Crisia eburnea is here mapped with phalloidin, DAPI and antibodies directed against acetylated α-tubulin and serotonin. Innervation of most muscles as well as the ganglion of C. eburnea is described, and several new details are reported, for example, on the additional and branched ectodermal muscles of the cystid, the presence of subtentacular muscles, the retractor muscles being distinctly striated and the presence of an additional pair of lateroabfrontal nerves in the proximal part of the tentacles. The serotonin-like immunoreactivity in the nervous system of C. eburnea shares many features with those of the other bryozoans studied so far, which probably reflects a common ancestry of the neural architecture. However, the nervous system shows somewhat less complexity compared to that of the sister clade, Eurystomata, and contains fewer cells and nerves compared to the cyclostome Cinctipora which has much larger zooids and more than eight tentacles. No interzooidal neural connections were found in C. eburnea, which is in agreement with the individual response of the zooids.     

Stable isotope compounds - production,detection, and application

Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies.     

Simplified Equation to Extract Diffusion Coefficients from Confocal FRAP Data

Quantitative measurements of diffusion can provide important information about how proteins and lipids interact with their environment within the cell and the effective size of the diffusing species. Confocal fluorescence recovery after photobleaching (FRAP) is one of the most widely accessible approaches to measure protein and lipid diffusion in living cells. However, straightforward approaches to quantify confocal FRAP measurements in terms of absolute diffusion coefficients are currently lacking. Here, we report a simplified equation that can be used to extract diffusion coefficients from confocal FRAP data using the half time of recovery and effective bleach radius for a circular bleach region, and validate this equation for a series of fluorescently labeled soluble and membrane‐bound proteins and lipids. We show that using this approach, diffusion coefficients ranging over three orders of magnitude can be obtained from confocal FRAP measurements performed under standard imaging conditions, highlighting its broad applicability.     

Testing for Starch,Respiring Tissues,and Vascular Bundles: Inquiry-Based Seed and Stem Anatomy Labs

In this article, the authors present lab exercises in which students use the microscope to study cells. After learning how to recognize the parts of a cell, differentiate between types of cells, and identify the nucleus, the students study blood samples from both familiar and “unknown” animals. The activities allow students to work independently and to become more proficient at microscope use. Students also gain a deeper understanding of the more “invisible” world of science.     

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a modified two-photon microscope¹. As opposed to conventional approaches (raster scan or wide field based on a stack of frames), the 3D orbital tracking allows to localize and follow with a high spatial (10 nm accuracy) and temporal resolution (50 Hz frequency response) the 3D displacement of a moving fluorescent particle on length-scales of hundreds of microns². The method is based on a feedback algorithm that controls the hardware of a two-photon laser scanning microscope in order to perform a circular orbit around the object to be tracked: the feedback mechanism will maintain the fluorescent object in the center by controlling the displacement of the scanning beam^3-5. To demonstrate the advantages of this technique, we followed a fast moving organelle, the lysosome, within a living cell^6,7. Cells were plated according to standard protocols, and stained using a commercially lysosome dye. We discuss briefly the hardware configuration and in more detail the control software, to perform a 3D orbital tracking experiment inside living cells. We discuss in detail the parameters required in order to control the scanning microscope and enable the motion of the beam in a closed orbit around the particle. We conclude by demonstrating how this method can be effectively used to track the fast motion of a labeled lysosome along microtubules in 3D within a live cell. Lysosomes can move with speeds in the range of 0.4-0.5 µm/sec, typically displaying a directed motion along the microtubule network⁸.