The semaphorin family consists of a set of secreted and transmembrane proteins which contain a domain of approximately 500 amino acids called the semaphorin domain. The investigation of the role of semaphorin proteins in the nervous system has established them as chemorepellents of axons. Recent studies have identified the semaphorin proteins on the surface of cells in the immune system and in the genomes of two lytic viruses. These strongly suggest the possible involvement of the semaphorin proteins in the immune system. This study aims to understand the expression patterns of four semaphorin genes, Sema3B, Sema4A, Sema4F, and Sema6C in the lymphoid tissues of wild type mice. These proteins were chosen to represent the three subfamilies III, IV, and VI. The first family contains secreted proteins which have immunoglobulin domains (III), the second contains transmembrane proteins which have immunoglobulin domains (IV), and the third contains transmembrane proteins which do not have immunoglobulin domains (VI).

During fertilization in the sea squirt, Ascidia ceratodes,the penetration process of requires mitochondrial translocation, a process that defines sperm activation in this species, to generate the driving force for passage through the vitelline coat. When a sperm cell come into contact with an egg, the mitochondrion translocates off the head and migrates along the tail via an actimmyosin-dependent process. The presence of actin and myosin on the head and tail has been demonstrated. However, the nature of the relative distribution of filamentous actin (F-actin) and monomeric actin (G-actin) has not been thoroughly studied. And, whereas the signaling cascade that leads to myosin activation has been studied, the events leading to actin polymerization and whether it is required for mitochondrial translocation has not.

This project addresses two research questions: What is the distribution of F-actin and G-actin in unactivated and activated sperm cells? And, can preexisting F-actin support mitochondrial translocation or must actin polymerization occur simultaneously with the mitochondrial translocation process?

The earliest events in ascidian fertilization require sperm-egg recognition, sperm activation and penetration of the egg's protective barriers before sperm-egg fusion can occur. Species selective recognition is known to depend on recognition by sperm of egg N-acetylglucosamine sites. Binding to these sites triggers the defining event of ascidian sperm activation called mitochondrial translocation. in this process, the mitochondrion becomes anchored to follicles cells surrounding the egg and then rounds up, moves to the base of the head and translocates onto the tail. This actimmyosin-dependent process provides the force for penetration. Activation of myosin depends on a signaling pathway that leads to internal Ca2+ release and external Ca2+ entry.

In order for actimmyosin interactions to provide the force for penetration, the mitochondrion must be anchored to the outer surface of the egg complex. Presumably this anchor must also attach to actin filaments that serve as the track for the mitochondrial translocation process.

Among land plants, lower vascular plants produce the most elaborate of all male gametes. in order to characterize the degree of variability in sperm cell architecture among ferns, this scanning electron microscope study was undertaken on three highly disparate genera: Ceratopteris(a derived leptosporangiate fern) Angiopteris(a derived eusporangiate fern) and Psilotum(a putatively basal eusporangiate fern).

Mature gametophytes were placed in 0.01M phosphate buffer (pH ca. 7.2) or distilled water until spermatozoids were released. Gametophyte portions were removed and the spermatozoid suspension fixed with 2% glutaraldehyde in 0.05M phosphate buffer. Post-fixation utilized 1% aqueous osmium tetroxide for lhr, followed by rinsing and dehydration in ethanol (10 min @ 25, 50, 75 and 100%). The dehydrated pellet was suspended in 100% hexamethyldisilazane, immediately centrifuged and the pellet deposited onto clean glass coverslips. Specimens were dried at 60°C, sputtered with ca. 350 A of palladium/gold and imaged in a Hitachi S570 SEM.

Toxic dinoflagellates gained notoriety for their devastation to coastal and island economies, causing damages totaling in the millions of dollars that included losses of harvestable resources, clean-up costs, as well as cancellation of holiday reservations in popular tourist/recreational areas.3 These red tide blooms sparked an urgency for obtaining information pertaining to the dynamics of toxin production, but understanding the mechanisms of toxin production have proven to be difficult to pin point. This study tested the hypothesis that cells grown under various light intensities undergo structural and compositional changes and served as a basis for future biochemical studies of Prorocentrumhoffmanianum.

We examined ultrastructural changes to the chloroplast in cells from monocultures of Prorocentrum hoffmanianum grown in three different light intensities, via a transmission electron microscope and a fluorescent light microscope. The full or normal growth chamber intensity of ca. 5000 lux represented the control group referred to as the full light treatment.

Mature sperm cells of Ceratopteris richardiiare spiraled over three revolutions and contain a locomotory apparatus with approximately 70 flagella attached at the cell anterior (Fig. 1). Abundant organelles are dispersed along the inner surface of an elongated, coiled nucleus (Figs. 1, 3, 8). The cytoskeleton comprises a network of microfilaments that encases the nucleus (Fig. 6) and two distinct microtubule arrays: a microtubular ribbon (spline) and flagella with anchoring basal bodies (Fig. 3). This study uses light, fluorescence, transmission electron (TEM), and scanning electron microscopy (SEM) to characterize cell organization in a motility impaired mutant sperm line of Ceratopteris.Because motility mutations likely involve the cytoskeleton, emphasis was placed on observing microtubule and actin arrays in the mutant compared to wild-type spermatozoids. Protocols follow Hoffman and Vaughn for TEM and Schmitt and Renzaglia for SEM. Microfilament arrays in relation to the nucleus were examined by rhodamine-phalloidin and DAPI fluorescence.

The field number of the objective lens limits the field of view in a conventional compound microscope; even at very low magnification, the microscope does not allow observation of large pieces of specimen at once. This made the observation of organs and large pieces of tissue sections inconvenient. in the course of studying the development of maize stem, we encountered the need of digitizing large hand sections for 3D reconstruction. Splicing a series of images that are taken at different positions to form a montage is not acceptable, because the jointed image suffers from mismatch due to lens distortion. Considering the resolution needed in our study, one alternative is to use a consumer flatbed scanner designed for a personal computer. in order to adapt the conventional scanner for wet tissue scanning, an Acer 620TPC flatbed scanner, equipped with a trans-illuminator, was modified (FIG 1).

Thermal environment exerts a strong influence on lizard life histories by constraining seasonal activity time, fecundity, growth, and embryonic development. in cold climates, extending the duration of egg retention within the female's body permits embryos to develop more rapidly than would be possible at ambient nest temperatures. The duration of egg retention time in the oviduct is largely constrained by the ability of the growing embryo to uptake oxygen and release carbon dioxide. Parchment shelled eggs of most squamates (lizards, snakes, and amphisbaenians) while permeable to water and gases, also acts as a diffusive barrier to gas exchange. As a result, most taxa with extended egg retention exhibit a concomitant reduction in eggshell thickness.

To assess the influence of thermal environment on egg retention time, I sampled eggs from the lizards Sceloporus occidentalis and Sceloporus graciosus(Phrynosomatidae) from three populations at high, intermediate, and low elevation, in the San Gabriel Mountains of Southern California.

A database cataloguing SEM micrographs of pollen specimens can be useful for several purposes. The primary reason would be for educational purposes. The images could be used to study pollen structure, as well as the relationship between pollen and pollinator species. Identification of pollen can be of potential use for medical purposes (such as combating allergic reactions to pollen), and for comparison in a forensic investigation. At the Biology Department of California State University, San Bernardino an ongoing project is underway to construct a database of pollen samples, focusing on local species. The micrographs are created at the Electron Microscope and Images Analysis Center located in the School of Natural Sciences at Cal State San Bernardino using a Hitachi S-2700 SEM. The database will be made available to the public and updated periodically via the Biology Department website (http://biology.csusb.edu).

All specimens were first fixated by placing the pollen grains in a syringe filter and injecting a 2% formaldehyde/4% glutaraldehyde formula and incubating overnight.

Electrodeposition of molybdenum dioxide (using the step edges of highly oriented pyrolytic graphite as nucleation templates) is used to form precursor nanowires ranging in diameter from 10 nm to one micron with many exceeding one-half millimeter in length. Subsequent treatment with hydrogen gas above 500°C reduces the wires to conductive metallic molybdenum. (Science, December 15, 2000, 290 (5499) 2120, selected as cover story). Currently, this is the only method which exists to create millions of ordered nanowire arrays with such high aspect ratios. A film of either polystyrene or cyanoacrylate polymer is used to lift the wires off of the conductive graphite substrate making electronically isolated wires. Electronically isolated wires such as these hold promise to be sensors, electronic interconnects or as precursors for growing more complex electrodeposited circuitry.

The discovery of a method to deposit nanowires is just the beginning. By using a piece of a double-sided copper-clad circuit board as a support, the polymer containing nanowires can be made into a robust sensor device.

Introduction: “In time, and with water, everything changes.” —Leonardo da Vinci The crystallization of soluble salts in porous building materials is a widespread weathering process that results in damage to important monuments and archaeological sites. Salt weathering by thenardite (sodium sulfate) and mirabilite (sodium sulfate decahydrate) is especially destructive, yet is still not fully understood. Halite (sodium chloride) in contrast, is one of the least damaging salts. Previous work has also demonstrated the importance of airflow in salt weathering. Here we present new data that help explain why sodium sulfate is so damaging and also show how crystallization modifiers and changes in airflow can reduce salt damage in laboratory experiments.

Damage Mechanism: The behavior of sodium sulfate was documented using saturated solutions and oolites from Monks Park limestone (a stone well known to be vulnerable to salt damage) as test samples. Damage was evaluated based on the degree of cracking of the oolite.

Forensic science incorporates many different scientific disciplines: criminalistics, toxicology, pathology, entomology, engineering, psychology, accounting, etc. Criminalistics incorporates such diverse areas as crime scene investigation, sexual assault evidence, DNA analysis, firearms identification and comparison, drug analysis, impression evidence, and trace evidence.

A variety of microscopes and microscopical techniques are used to answer “real world” questions about physical evidence in criminalistics. The microscopes most often used include stereo (dissecting), biological (brightfield), polarizing light, phase contrast, fluorescence, transmitted light comparison, reflected light comparison, and scanning electron. Additionally, detectors from different areas of the electromagnetic spectrum have been added to microscopes to enhance the information obtained from a specimen: infrared, visible-ultraviolet, and x-ray. to gather more information about the specimen with visible light microscopes, dispersion staining(1), contrast enhancement techniques(2) fusion methods(3), chemical staining(4), and micro-chemical tests(5,6) can be integrated into the analytical scheme.

The economic importance of animal hides and skins as the source material for the natural leather industry is significant world-wide, and in some countries of the developing world the livelihood of a large proportion of the population depends upon it. Consequently, it is understandable that anything affecting the quality of the source material and the finished product has major economic, industrial and sociological significance. It is also inevitable that a product that is so widely-used in many ways by most of the population will become an important source of evidence in forensic investigations.

Quality control procedures in the leather industry involve monitoring the progress of the hides and skins from the growth stages of the animal, through the slaughter, storage, transportation, curing, tanning and finishing processes, to the sale and distribution of the finished product. There are many factors during these stages that can affect quality of finished leather, amongst the most important of which are mechanical and parasite damage during growth, biodeterioration and mechanical damage between slaughter and curing, mechanical, heat and chemical damage during curing, tanning and finishing.

Fiber cement roofing shingles from condominiums in Hawaii were examined for deterioration using optical and scanning electron microscopy. The product has a 50 year warranty and had been in service since 1994. Shingle samples were taken in August and September, 2000 after a growing volume of reports of roofing deterioration were received by the condominium association. Close-up visual inspection confirmed that the roof areas showing deterioration were covered with a black growth. Roofing samples from areas exhibiting deterioration, areas with no deterioration, and new material were compared by microscopy.

Examination of the black growth by optical microscopy revealed it to be primarily the Cyanobacterium, Scytonema sp.This is a filamentous organism found from the Arctic to the Antarctic, and is common to Oahu and Maui.’ Other organisms observed to be present are Chroococus sp., Gloeocapsa sp., Aphanocapsa sp., Oscillatoria sp.,a very few Trebouxia sp.and lichens.

The rapid rise of energy costs in the 1970's and early 1980's brought about a number of energy conservation measures which are still in use today. Changes made in heating, ventilating and air conditioning (HVAC) systems increased the recirculation of conditioned air within buildings, while leakage of air through the building shell was sharply reduced. Air movement in modern buildings is typically under the control of centrally operated HVAC systems which do not allow for local control of airflow in particular areas by the occupants. Problems with the quality of indoor air in the work environment have resulted from some of these measures and collectively many of these phenomena have been referred to as the Sick Building Syndrome (SBS). SBS is a complex of symptoms, including eye and mucous membrane irritation, headache, cough, dizziness, chest tightening, fatigue and general malaise, which occur more frequently than would normally be expected (greater than 20%) among the occupants of a building.

Indoor air quality concerns are becoming increasingly important in the United States as a result of a greater awareness of the harm fungi can cause to structures and the people living in those structures. By making our homes and offices more energy efficient and by making heating and ventilation systems more complex we have also created some indoor air quality problems.

Microscopical indoor air investigations are growing rapidly as evidenced by the number of asbestos and other labs getting into the fungal spore identification business. Many companies are growing by 20% a month and cannot find enough qualified microscopists to perform the identification of the fungi..

There is a real need to revitalize the teaching of light microscopy to solve indoor air problems. Fungal spores and pollen are the common culprits that cause indoor air quality problems that can be studied with the light microscope. with proper training, an indoor air quality investigator can make better use of their elegant analytical tool, viz.

Atmospheric aerosols are often investigated in order to gain insight into their effects on the global radiative heat budget, optical properties of the atmosphere, and their effects on human health. Characterizing the seasonal behavior of these aerosols is fundamental in understanding their climatological and air quality impacts. As part of a larger program to study the present and recent history of chemical species transported to Greenland, we analyzed a seasonal cycle of total aerosol matter scavenged from the air by surface snow.

During a “winter-over” experiment in Summit, Greenland, extending from June 1997 through March 1998, kilogram quantities of surface snow were collected, melted, and filtered onto high-purity quartz fiber filters in the field. Upon the receipt of these filters at NIST, the total particulate matter was removed from the filters and transferred to boron substrates with protocols involving resuspension, centrifugation, and filtration.’ Previous techniques that quantified multi-element particles used several different substrates.

The Indian Ocean Experiment (INDOEX) was conducted in Feb.-Mar. 1999 in a large area of the Indian Ocean, Bay of Bengal, and Arabian Sea to investigate climate forcing produced by pollutant aerosol particles being transported out of India, Pakistan, and Indochina during the Northeast (“Dry“) Monsoon2. Pollutant aerosols can be transported a thousand km or more by prevailing winds as far south as the Inter-tropical Convergence Zone (ITCZ), the convective band that separates Northern and Southern Hemisphere tropospheric air. We present here results from TEM examination of aerosol particles collected on INDOEX research flights of the NCAR C-130 aircraft.

The climate forcing properties of sulfate aerosols over the oceans have long been recognized2. Sulfate and other particles scatter incoming solar radiation, reducing the amount of light (and heat) incident on the ocean surface and thus causing a cooling effect which may locally counter some of the warming effect due to greenhouse gases.

The present work is a small portion of a multi-disciplinary science-based study of the physicochemical properties of respirable aerosols containing beryllium. The working hypothesis is that Chronic Beryllium Disease (CBD) is by controlled dissolution of Be particles in the lung. Recent studies have shown correlations between specific Be production processes and the development of Be sensitivity and CBD. in Beryllium Oxide (BeO) production, 9.8% of the workers develop a sensitivity to Be and 4.9% develop CBD. in vitro cellular dose-response relations have been observed for BeO particles.

This study involves a characterization of BeO materials sampled from the air stream around the production process at Brush Wellman Inc. (Elmore, OH) and laboratory-prepared BeO. One purpose of this work is to determine if lab-prepared material is a good surrogate for the process-generated aerosols for cellular dissolution studies. Both materials were size-separated into six fractions using a five-stage cyclone followed by a electrostatic precipitator (ESP).

In the paper, we firstly publish a new method of internal micrographic visualization of semiconductor and IC. The quality and reliability of the semiconductor materials (SM) and the integrated circuits (IC) have always been concerned Having a high resolution, high reliable and nondestructive detection method is the key element for their improvements.

Silicon oxide layers are used to provide the electrical insulation in the multi-structured ICs. The IC device surfaces are often protected by silicon oxide and silicon nitride layers. Therefore, these insulation layers also cover any inhomogeneity and defect located within the IC devices. It is necessary to have an examining method to detect those defects that are under the insulation layers without damaging the samples. However, the conventional scanning electron microscope (SEM) cannot be utilized to image and examine the surfaces that are positioned below the insulation layers.

Novel nondestructive and contactless method has been developed in our laboratory to obtain the internal micrograph that crosses the surface of the semiconductor material and the integrated circuit.