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.

The parasitic dinoflagellate Haplozoon is found in the intestine of marine polychaetes. It is composed of a chain of cells that hang from the intestinal wall into the lumen, and releases daughter cells from the posterior end of the chain which leave the host and reinfect other polychaetes. Few studies exist in the recent literature regarding Haplozoon and it has not been reported from the Gulf Coast of the United States. This study reports the genus Haplozoon from the maldanid polychaete Axiothella mucosa in St. Andrew Bay, Florida, and examines the structure of the organism by light and electron microscopy.

Axiothella mucosa was collected in St. Andrew Bay, Florida and maintained in seawater at the Troy State University campus. Haplozoon spp. was prepared for whole mounts by smearing minced setigers of the worms onto a slide with a drop of seawater.

The effect of starvation on the mucosa of the Aphanius dispar stomach is investigated. The gastric erosion resulting from stress due to starvation over a period of 24 - 120 hours has been described at the ultrastructural level.

Specimens of A. dispar with a total length (TL) range of 30.4-46.3 mm, weighing from 0.43-0.70 gm were collected from Wadi Al-Khod, Sultanate of Oman (Lat. 23° 30’ N; Long. 58 ° 40'E). Thirty six fish were acclimatized for two weeks and were fed with Tetramin flakes, ad libitum, twice daily. Thirty of these fish were subsequently starved in a chamber separated from the six control fish that were fed normally in the same tank. Six starving fish were randomly sacrificed at 24, 48, 72, 96 and 120 hr intervals for histological studies. At the end of the experiment, the six control fish were also sacrificed. Stomachs were fixed and processed for TEM.

In the present study, the myofibril regeneration in the long-term cultured fish cardiomyocytes was studied with immunocytochemistry.

Adult Tilapia heart was dissociated into a single-cell suspension with collagenase and protease-minced tissue method. The culture medium was Eagle's minimal essential medium (MEM) with Earle's salts, supplemented with 10% fetal calf serum, 1 x nonessential amino acid mixture, 100 IU/ml penicillin G, and 100 μg/ml streptomycin. The cultured cells were grown in a humidified CO2 incubator at 28°Cand in a medium without glutamine for eliminating fibroblast contamination. In the initial 24 h culture, the elongated-shape cells gradually shortened from their both ends and rounded up. Over 5 to 6 days postcultivation, the cells attached to the bottom of the culture flask and began to protrude pseudopodia. The cells could not be subcultured and also proliferated indefinitely. The life span of cells in culture was 30 to 60 days.

Apoptosis (programmed cell death) is an important form of physiological cell death displayed under divergent conditions by an enormous variety of tissues. Apoptosis can be characterized by cell shrinkage, membrane blebbing, and DNA fragmentation (1). Data from recent reports have suggested that many types of cancer are accompanied by the loss of apoptotic ability (2). Many manufacturers have hailed colloidal silver as an effective treatment of many diseases including cancer (3). The FDA has recently finalized a rule stating that drug products containing colloidal silver or silver salts are not recognized as safe and effective. They conclude that product labels claiming that scientific evidence suggests otherwise are incorrect (4). In this study we undertook to examine the effects of colloidal silver on both Raji cells, a B lymphocyte lymphoma, (ATCC # CCL-86) and normal, peripheral blood lymphocytes (PBL). We noted a decrease in viability of 90% in both Raji cells and lymphocytes after exposure to colloidal silver.

Proper nutrition and vitamin consumption have long been associated with lower risks for many human cancers. Data from recent studies have suggested that exposure to antioxidant vitamins and vitamin combinations can induce genetic programed cell death, apoptosis, in human cancer cells. ‘“3 In this study, we report on the induction of apoptosis in HT-29 human colon adenocarcinoma cells after exposure to low doses of 13- c/s-retinoic acid (RA) and vitamin E succinate (VES). Induction of apoptosis was seen only in cancerous colon cells and not in normal human colon cells when exposed to RA and VES in combination, but not when exposed to either vitamin alone.

Cultures of HT-29 cells were seeded in 6 well plates at 10,000 cells/well and grown at 37°C, 5% C02 in RPMI 1640 medium supplemented with 10% fetal bovine serum.