Samples of albino mice cerebellar cortex were processed by the cryofracture method for scanning electron microscopy and examined with the field emission scanning electron microscope (FESEM). Albino mouse cerebellar cortex was excised, cut into 1-2 mm slices and inmersed in 4% glutaraldehyde in O. l M phosphate buffer solution, pH 7.4, for 24h at 4°C; and postfixed for 1 h in a similarly buffered 1% osmium tetroxide solution. Specimens were dehydrated in a graded serie of ethanol (30, 50, 70, 80, 90 2x100%) prior to wrapping individual tissue pieces in preformed absolute ethanol filled parafilm cryofracture packets. Rapid freezing of packets was performed by plunging into LN2. First, the packet was transferred from the LN2 storage vessel with LNT chilled forceps in order to avoid themial damage. Secondly, the cooled fracture blade was removed from the LN2, the packet was orientated under the blade, and immediately struck with a heavy tool.

The bone interface to implanted biomaterials (both orthopaedic and dental implants) is the critical component for initial fixation of these uncemented biomedical devices. The mechanism of osteogenesis at the biomaterial surface after surgical placement is critical to understand to enhance osseointegration , and thereby implant success. The purpose of this paper is to report comprehensive and correlative electron and light microscopic observations from a five-year study involving the bone interface to 120 implants placed into 30 adult animals.

As a model system to evaluate bone and associated tissue interfaces to implanted biomaterials, 120 endosteal dental implants were placed into the mandibles of 30 adult mongrel dogs. Premolars were extracted and the sites were allowed to heal for 2 months prior to implantation. Surgery employed low speed drilling, copious internal and external irrigation and followed manufacturer recommendations for these commercially available implants.

Aqueous mixtures of oppositely charged surfactants spontaneously form equilibrium phases of unilamellar vesicles.1 The wide variety of surfactants that display this behavior allows control over vesicle charge, size, and polydispersity. This may be useful for new applications in drug delivery, nanomaterials synthesis, and as tests of theoretical concepts of membrane organization and interactions.

A subtle competition between the entropy of mixing and the elastic properties of surfactant and lipid bilayers determines their phase behavior and morphology. The curvature energy per unit area of bilayer, fc, is

where R1 and R2 are the principle radii of curvature, K is the curvature modulus, and is the saddle-splay modulus. The spontaneous curvature, l/ro, is nonzero only if there is asymmetry between the two sides of the bilayer.

A highly significant correlation between reduced incidence of breast cancer in Asian countries and consumption of soy suggests that specific components in soy may have anticarcinogen activity. The soy ingredients genistein and daidzein have been found to inhibit induced breast tumors in animal and cell culture models. These isoflavones are known to be both agonists and antagonists of estrogen activity but only genistein is also a potent inhibitor of tyrosine kinases which are the primary intracellular signalling mechanisms associated with the regulation of cell proliferation.

Genistein promotes cell proliferation in breast cancer cells at low concentrations in its function as estrogen agonist but inhibits cell proliferation at high concentrations (30 μM). In order to investigate the underlying mechanisms by which high concentration of genistein inhibit cell proliferation we treated MCF-7 cells with increasing concentrations of genistein and analyzed cells by immunofluorescence and transmission electron microscopy (TEM).

Striated skeletal muscle has been considered radioresistant because it is highly differentiated and post-mitotic. Striated muscle does, however, respond to irradiation with morphological and biochemical changes after short and long latency periods; vascular and/or neurological impairments might contribute to the delayed responses to irradiation.

The objective of the present study was to determine the susceptibility of three amphibian muscle fiber types to Co60 irradiation. In amphibians, the three major fiber types are 1) large twitch fibers, which contain low levels of mitochondrial enzymes and lipids, but intermediate levels of glycogen; 2) small twitch fibers, which contain high levels of both glycolytic and mitochondrial enzymes (FIG. 1); and tonic fibers, which contain low levels of all three histochemical markers. Thus, the determination of susceptibility of different amphibian fiber types to irradiation might indicate whether the metabolic characteristics of the fibers, rather than morphological or electrical properties, could serve as an early indicator of radiation damage.

Complexes formed during interaction of cationic liposomes with polynucleotides such as DNA (CLDC) self-assemble into a variety of polymorphic structures. They display bilayer (FIG. 1-5) and non-bilayer structures (FIG. 6). We have recorded bilayer structures such as spaghetti/meatball-type structures (FIG. I), map-pins (FIG. 2) spherical particles and invaginated liposomes (FIG. 3, 4) and oligolamellar structures (FIG. 5). The non-bilayer lipid arrangements include honeycombtype structure (Hn, FIG. 6) and cubic phase lipids.

We have chosen mainly freeze-fracture electron microscopy (FIG. 1-3, 5,6) but also cryo-electron microscopy (FIG.4) for recording polymorphic structures, and for studying factors and conditions triggering the formation and stabilization of specific structure types. Furthermore, we took microscopically snapshots of the interaction of specific structure types with cultured cells. In order to find out the “active” structure in terms of transfection, we investigated the transfection activity both in vivo and in vitro of CLDC, and studied in parallel their morphology in serum as well as in cell medium.

Single molecule detection has been achieved via many highly sophisticated microscopic techniques. Here we describe the detection of single molecules with conventional epifluorescent microscopy. The key to the technique is the use of DNA dendrimers DNA dendrimers have demonstrated utility in nucleic acid blots, Southerns, Northerns, etc. Typically DNA dendrimers yield 50-100 fold gain in signal over comparably labeled oligonucleotides. Immunodendrimers, DNA dendrimers conjugated to antibody molecules, have also been constructed and utilized in western blot assays. Individual, i.e. single molecule, 4- layer dendrimers, are readily detectable as point sources via conventional fluorescence microscopy and are useful for in situ hybridization and flow fluorescence quantitation.

Nucleic acid hybridization is the underlying principle behind DNA dendrimer assembly. The “monomer” of DNA dendrimers consists of partially double stranded heteroduplexed DNA. Each monomer has an approximately 50 base double stranded “waist” surrounded by four approximately 30 base single stranded “arms”.

Successful gene therapy is dependent upon well regulated, long-term expression of transgenes in the target tissue. The development and production of very high quality vectors are one of the most important steps leading to delivery of the desired genes. Although several types of vectors have been used for the delivery of transgene to the target cells of the host, our institute routinely uses recombinant viral vectors including adenovirus and adeno-associated virus (rAAV) for gene therapy studies. To assure high quality of the viral vectors being used for animal experiment as well as clinical trials, a number of quality control protocols, including electron microscopy, was developed and implemented to monitor the overall purity, and density of the vectors.

Transmission electron microscopy (TEM), combined with optimized procedure of negative staining for virus, offers a unique means to generate visual data of the vector preparation; and it has gained increasing application to help assess the quality of vectors.

The inducible SOS response increases the ability of bacteria to cope with DNA damage through various DNA repair processes in which the RecA protein plays a central role. We find that induction of the SOS system in wild-type E. coli bacteria results in fast and massive intracellular coaggregation of RecA and DNA into lateral assemblies, which comprise substantial portions of both the cellular RecA and the DNA complement. The structural features of the coaggregates and their relation to in-vitro RecA-DNA are consistent with the possibility that the intracellular assemblies represent a functional entity in which RecA-mediated DNA repair and protection activities occur.

Bacterial chromatin is demarcated in electron micrographs of metabolically active cells as amorphous ribosome-free spaces that are irregularly spread over the cytoplasm (Fig. A). Wild-type E. coli cells exposed to DNA-damaging agents that induce the SOS response reveal a strikingly different morphology (Fig. B).

The Scanning Transmission Electron Microscope (STEM) facility at BNL is an NIH Biotechnology Research Resource and as such is available to users with suitable projects, free of charge. Currently, many of our users' projects involve studying the structures of a variety of filaments. Most of these are of biological origin, although a couple involve conducting polymers. The STEM has a long history of being used to study different types of filaments and resolving controversies about their structure.

The mainstay of the STEM is mass analysis on unstained, isolated, freeze-dried samples. On these, the STEM can collect in-focus digital data directly. In a scan (8 sec. in real time) of a sample, at each of 512x512 picture elements (pixels), the number of electrons scattered into two annular detectors is recorded. For each pixel, the number of scattered electrons is directly proportional to the mass thickness in that pixel.

Type I collagen fibrils provide a structural framework for mineral nucleation, growth, and development during calcification of tissues such as bone, dentin and tendon of many vertebrates. Previous work has described a general mechanistic model of normal collagen- mineral interaction in which nucleation events take place on collagen surfaces and in channels or gaps defined by periodic (64-70 nm) collagen hole and overlap regions. These sites are created in early collagen molecular and macromolecular assembly. The model suggests that, once nucleated, the mineral within channel spaces grows into irregularly shaped platelets of small size and these develop into larger platelets whose detectable crystallographic c-axis direction parallels the long axis direction of the collagen fibrils with which they associate. The fate of mineral nucleated on collagen surfaces is unclear, although it is known that the volume of extracellular tissue space between adjacent collagen fibrils, like that within the fibrils, also becomes mineralized.

Nodes of Ranvier are sites on myelinated axons where the insulating layers of myelin are interrupted. They represent an excellent example of a complex cellular structure that contains highly differentiated sub-regions. At these sites of cell-cell specialization, ion fluxes occur which are required for propagation of action potentials. Myelinated axons and their nodes of Ranvier represent an important evolutionary advance for vertebrates that permit very rapid propagation of action potentials without large increases in axonal diameter. This physiological achievement is based on adaptations at a molecular level resulting in an elegant cooperation between glial cells and the axons of neurons.

The organization and sub-specialization of the molecular components of the node of Ranvier are complex but often inter-related. The nodal region of axons are enriched in several channel and pump proteins including the voltage-gated Na+ channel, Na+-K+ ATPase and a number of different K+ channel isotypes.

Pulmonary surfactant is secreted by alveolar type II cells and reduces the surface tension at the air-liquid interface of alveoli. After pulmonary surfactant is secreted into the alveolar space, it transforms into tubular myelin, a highly ordered 3-dimensional lattice-like structure. Pulmonary surfactant protein C (SP-C), one of four pulmonary surfactant associated proteins, is synthesized as a proprotein which is processed to biologically active 35 amino acid mature peptide by proteolytic cleavage of N- and C-terminal peptides from the SP-C propeptide (Weaver, 1998). Processing of SP-C is linked to the expression of pulmonary surfactant protein B (SP-B): In SP-B deficient mice, SP-C is misprocessed and present in the bronchoalveolar lavage (BAL; Vorbroker et. al., 1995a). Although the intracellular localization of SP-C is well established (Vorbroker et. al., 1995b), there is no ultrastructure study available regarding the localization of misprocessed SP-C in the airway. In this study, we used transgenic mice expressing a truncated human SP-B propeptide (hSP-BΔC+/+) bred into the murine granulocyte macrophage colony stimulating factor (GMCSF) and SP-B double knockout background (hSP-BΔC+/+: GMCSF-/-: mSP-B-/-) as a model to localize the misprocessed SP-C by cryoimmunogold labeling.

Lung surfactant stabilizes the pulmonary air-water interface, by enriching this interface with films of amphipathic phospholipids. These films reduce the surface tension of the air-water interface to very low values (∼ 1 mN/m) at end expiration and prevents alveolar collapse. Surfactant contains mainly phospholipids (90%), and small amounts of associated proteins. Among the phospholipids, saturated dipalmitoylphosphatidylcholine (DPPC) and monounsaturated phosphatidylcholine are the main surfactant components, although significant amounts of other lipids are also present (1). DPPC is the only component of surfactant which exists in gel phase at physiological temperature, films of which can reduce the air-water surface tension to low values. DPPC films can undergo a fluid to gel transition with increase in the molecular packing leading to superstructures or domains (2). However it is not clear how the molecules of surfactant pack at the air-water interface to form highly compact films, and if DPPC phase segregate in such films.

Tadpole shrimp inhabit temporary freshwater pools and ponds where their occurrence is largely regulated by rainfall events and water temperature. When dry basins are flooded, cysts of Triops imbibe water and hatch to produce rapidly growing, carapaced larvae. While previous studies show anostracan (fairy shrimp) cyst-surface morphology often species specific, few studies illustrate shell ultrastructure of Triops and none has considered T. longicaudatus. Here we examine the shell of T. longicaudatus (Notostraca) and compare its fine structure to other species of Triops and to that of Artemiafranciscana(Anostraca), which we previously studied.

Cysts, produced in culture from Utah broodstock, were purchased from Triops, Inc., 1924 Creighton Rd., Pensacola, FL 32504. Thin sections of cysts were prepared for transmission electron microscopy (TEM) as previously described (Fig. 1). Cysts were also examined with scanning electron microscopy (SEM), dry, whole or fractured (Figs. 2,3), or after imbibition and/or hatching in oxygen saturated, double-distilled water, at 25 ° C.

Mites, the second largest arthropod group after insects, occupy every conceivable terrestrial and aquatic habitat in our environment. They feed on plants, infest food products such as meat, cheese and grains, parasitize invertebrates and vertebrates, and transmit fungal, bacterial, rickettsial and viral diseases. Estimates indicate that as many as 1,000,000 species of mites may exist; however, partly because of their microscopic size, only about 40,000 species have been described and classified. During the last 30 years, researchers have increasingly utilized the greater magnification and depth of field available in a conventional scanning electron microscope (SEM) to supplement descriptions of mites that were historically based on light microscopic observations. In addition, this technique provided a better understanding of the relative positions and functionality of organs and improved attempts to elucidate their biology. However, before mites can be imaged with a conventional SEM, they are typically chemically fixed, dehydrated and/or thoroughly dried.

Silverleaf whiteflies, Bemisia argentifolii Bellows and Perring, feed on a wide variety of plants and are capable of causing significant economic damage. Host selection may be determined by a wide variety of factors. Adult whiteflies may feed on one leaf and then move to another, however, their feeding and oviposition choices may well determine the success of egg hatch and nymph survival. Current theory suggests that whiteflies feed (Fig. 1) and oviposit on the abaxial surface of leaves due to the closer proximity of phloem tissue. This is believed to be particularly important for nymphs which are stationary during much of their development and have shorter stylets than adults. We examined whitefly stylet penetration into cotton and hibiscus leaves using both light and scanning electron microscopic techniques.

Adult silverleaf whitefly stylets were found to range from 100 urn to more than 300 um in length.

Introduction:- The metacestode (larval stage) of Taenia multiceps, it is characterized by its big bladder fluid filled and multiple scoleces. Affect very frequently herbivorous mammals like sheeps, hares and rabbits (1); and occasionally humans (2), causing disorders very similars to that caused by Cysticercus cellulosae (3), the larval stage of Taenia solium. The adult parasite, Taenia multiceps, it is found in the intestine of domestic and wild carnivorous like dogs, wolves and coyotes.

In this paper we describe the morphology at the optical and electron microscope level of coenuri collected from hares.

Material and Methods.- Coenuri collected from hares, were dissected from muscle tissues and fixed in glutaraldehyde 2.5% in 0.1M phosphate buffer pH 7.4, postfixed in 1% osmium tetroxide in the same buffer. Inclusion in medcast resin (Pelco). Sections were stained with uranyl acetate and lead citrate, and observed in a Zeiss EM 109 electron microscope.

Pulmonary neuroepithelial bodies (NEBs) consist of clusters of innervated endocrine cells localized in human and animal lungs. They are prominent in late fetal and neonatal lungs and their density declines with increased postnatal age. Gas sensing functions of these structures have been suggested by Lauweryns and Cokelaere. Subsequent experiments show that chronic hypoxia leads to an increase in the size or number of NEBs, and prolonged hyperoxia also causes elevation of NEB numbers. Animals exposed to cigarette smoke also had an increased number of immunoreactive NEBs.

Inhaled nitric oxide (NO) can reverse pulmonary vasoconstriction induced by hypoxic breathing or ligation of ductus arteriosus in newborn and young animals. These studies led to clinical use of NO for treatment of pediatric patients with pulmonary hypertension. However, direct effects of inhaled NO on various components of the lung are not clearly understood.

The nuclear envelope in all eukaryotic cells is perforated by nuclear pores, that consist of the nuclear pore complex (NPC). The NPC is a highly complex supramolecular structure that plays a pivotal role in the trafficking of macromolecules and particles between the nucleus and the cytoplasm. During the past two decades a large body of information has accumulated on both the structure and role of the NPC. The diameter of NPC is about 120 nm and is composed of approximately 100 proteins.

The NPC structure has been elucidated using various electron microscopy techniques. The basic structure of the NPC is comprised of three concentric rings, each displaying an 8-fold symmetry. The cytoplasmic and nuclear rings are vertically integrated by eight spokes that approximately span the width of the nuclear envelope. A set of eight fibers extends from the nucleoplasmic ring into the nucleus, and are joined at the distal ends by a ring to form the so called basket.