bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of Leiomyosarcoma Invasive Phenotype
Authors: Márquez A , Fino HJ , Correa M , Tonino P , Sosa L
Published: July 2020

Malignant tumors are known to have an heterogeneous cell population. Metastases are supposed to be formed by subpopulations with high metastatic capability. These metastatic cells constitute the so called invasive phenotype. In that order of ideas, metastases could be pathologically different from their parent tumors if the invasive phenotype had distinct morphological features. The similarities or differences between primary tumors and their metastases have not been adequately studied at the ultrastructural level. In this work we report an electron microscopic study of liver leiomyosarcoma metastases which shows alterations not described in primary tumors of that kind.

Biopsies of liver metastases from a colon leiomyosarcoma were surgically obtained. Samples were processed with routine techniques for transmission electron microscopy and observed in a Hitachi H-500 electron microscope.

Some alterations usually observed in primary leiomyosarcomas were seen. They were presence of myofilaments with focal densities, nuclear changes, swollen mitochondria, and abundance of rough endoplasmic reticulum (Fig. 1).
Performance of Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) on Ethanol Fixed Microscopically Dissected Colonic Aberrant Crypt Foci (ACF)
Authors: Lasko CM , Salo D , Good CK , Bird RP
Published: July 2020

Identification of altered gene expression in colonie preneoplastic lesions may play a key role in early detection and prevention of colon cancer. Considering carcinogen treated rat colonie mucosa harbors a mixed population of both normal and aberrant crypts, it is of interest to independently examine the genetic profile of these two populations. The present study was designed to use a novel method whereby RT-PCR was performed on alcohol fixed ACF which were micro dissected from normal surrounding crypts.

Male F344 rats were injected with azoxymethane, a colon specific carcinogen, at a dose of 15 mg/kg body weight once weekly for 3 weeks. After 28 weeks colons were excised, flushed with RNAse free ice cold phosphate-buffered saline, fixed flat on filter paper, fixed in 70% ethanol and immediately frozen at -80°C After a minimum 24 hours colons were placed on the lid of a sterile, clear petri dish filled with ice.
Angiogenesis in Neoplasia; Insights from in Situ Hybridization Studies
Authors: Brown LF , Dvorak HF
Published: July 2020

The formation of vascular stroma (angiogenesis) is essential for tumor growth and may also influence invasion and metastasis. Quantitation of angiogenesis may serve as a prognostic marker in certain malignancies and novel therapies targeted at inhibiting angiogenesis may prove to play an important role in control of tumor growth.

In situ hybridization (ISH) studies have helped to define some of the molecular and cellular events responsible for the formation of vascular stroma in malignancy.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a multifunctional cytokine associated with tumor angiogenesis. Vascular endothelial cells express at least two tyrosine kinase receptors for VPF, flt-1 and KDR. VPF acts as an angiogenic factor in several ways. It is an endothelial cell growth factor, alters endothelial cell gene expression, induces endothelial cell migration, and it is also a potent inducer of microvascular hyperpermeability (50,000 times as strong as histamine).
Molecular Pathogenesis of Cerebral Malaria
Authors: Fujioka H , Aikawa M
Published: July 2020

Plasmodium falciparum, the most malignant human malaria, is responsible for 2-3 million deaths annually. These infections often involve blockage of the cerebral microvasculature by P. falciparum-infected erythrocytes (Fig. 1). This aspect is considered the major factor in the pathogenesis of cerebral malaria.

Upon invasion of the erythrocyte, P. falciparum immediately begins to remodel the infected erythrocyte. The adherence points of infected erythrocytes, termed knobs (Fig. 2 and 3), contain antigenically diverse 200-350kDa surface proteins (PfEMPl; Fig. 4). The PfEMPl variant surface proteins are encoded by a large and extremely diverse family of genes (var), and switches in the expression of var genes account for rapid changes in the antigenic and adhesive properties of P. falciparum-inkcted erythrocytes (2.4% per generation). Switches in the PfEMPl expression may not only affect the phenotype of the parasite strain but may also change its sequestration to endothelial cells. Genetic reorganization in this protein can lead to binding any of the following endothelial cell receptors; ICAM-1, CD36, thrombospondin, chondroitin sulfate (Fig. 5),2 ELAM-1, or VCAM-1.
Microscopic Evaluation of Oxidative Damage in Alzheimer Disease
Authors: Smith M A , Perry G
Published: July 2020

In the past five years, a case for oxidative stress in the pathogenesis of Alzheimer disease (AD) has been convincingly made. That link owes most of its existence to the microscopic detection of neuronal oxidative damage. Focusing on damage not only has the advantage that stable products are studied, rather than short-lived radicals, but also that damage can be morphologically defined. This latter aspect is critical since biochemical analysis of whole tissue is mostly of the accumulated damage from normal metabolism with aging of long-lived polymers in the extracellular matrix (Figure 1). The importance of damage is that it is the result most likely to be linked to pathology. Driven by the hypothesis that oxidative damage plays a role in the aggregation of insoluble protein in the lesions of Alzheimer disease, neurofibrillary tangles and senile plaques, we developed reagents to detect protein modifications related to glycoxidation, lipid peroxidation, peroxynitrite, free carbonyls and carbonyl-modification (Figure 2).
Toxic Impacts of Pesticide Mixtures on The Morphology of Red Shiner (Cyprinella Lutrensis) Gills At 23°C and 30°C
Authors: Messaad Ibrahim A
Published: July 2020

Herbicides and insecticides are applied in agriculture sequentially or simultaneously to control broadleaf weeds, corn rootworm larvae, and other soil pests. Pesticide application creates the potential for movement to aquatic habitats via sediment or runoff, hence affects non-target aquatic organisms. Histopathological changes of gill tissues have been suggested as powerful and sensitive measures of stress and well-being offish. Atrazine and terbufos were found to cause tissue damage and mortality in fish. Literature concerning the effects of pesticide mixtures to fish and other animals at the histopathological level are rare. The present study focused on the impacts of atrazine and terbufos mixtures on fish gills.

Cyprinella lutrensis were obtained from the Platte River in Nebraska, USA and maintained in the laboratory at 23 °C and 30 °C. They were exposed to 0, 1μg terbufos + 10 μg atrazine L-1, 10 μg terbufos + 100 μg atrazine L-1, and 100 μg terbufos + 1000 μg atrazine L-1.
Liver Ultrastructural Pathology in Cocaine Users
Authors: Finol HJ , Mondragón DD , González YM , Paradisi C , González N , Márquez A
Published: July 2020

Although liver function tests could be abnormal in humans taking cocaine the histopathological basis for this disorder has not been well established. Light microscopic studies have shown the existence of peripheral, centrilobular or diffuse necrosis. The only electron microscopic investigation we could find reports hepatocyte alterations including dilated rough endoplasmic reticulum, hypertrophy of smooth endoplasmic reticulum, and existence of phagolysosomes. In this work we report the liver ultrastructural pathology in chronic cocaine users.

Liver biopsies were obtained in five male patients, 25-44 years old. These patients had consumed cocaine and other drugs (marihuana, alcohol, amphetamines, etc..) for 7-30 years. All of them had altered liver function tests. Tissue samples were processed with routine techniques for transmission electron microscopy and observed in a Hitachi H-500 electron microscope.

Abnormalities observed included those previously reported as swollen rough and smooth endoplasmic reticulum, presence of autophagic vacuoles and lipid deposition.
The Redox Dysregulation Visualized by Electron Microscopic Localization of Cerium Perhydroxide in The Kidney of (Nzb X Nzw)F1 Mice.
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Nishikawa Megumi , Chen Li-Li , Igarashi Rie , Nakazawa Tomoko , Aikawa Eizo
Published: July 2020

Redox dysregulation is known as pathogenesis of renal involvement in autoimmune lupus mice [1,2]. However, the behavior of reactive oxygen species (ROS) is still unclear [3]. The purpose of this study is to make clear the localization of hydrogen perhydroxide which is generated as intermediate substances of radical reactions.

Modified Brigg's method [4] was used to determine the generation of ROS in renal tissues of (NZB x NZW)F1 mice. The renal specimens were incubated with a standard medium, which consisted of 0. IM tris-malate buffer (pH7.4) with 7% sucrose, lmM CeCl3 and lOmM aminotriazole at 37° C for 30 min and ultrathin sections were prepared and examined by electron microscopy. Lecithinized-recombinant-superoxide dismutase (SOD) was used as redox regulator, which is ROS inhibitor. SOD (1000 U/kg) was injected 3 times a week, tail-intravenously to Fl mice from 4 to 60 weeks of age. The mRNA of inflammatory cytokines and IkB was detected by RT-PCR method.
Programmed Cell Death (Apoptosis) in the Myocardium with Acute Myocarditis.
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Nishikawa T , Ishiyama S , Takeda K , Kasajima T , Abe S , Shimojo T , Ito H , Hiroe M
Published: July 2020

Acute myocarditis is a potentially lethal disease. However, the precise mechanism of myocardial damage in myocarditis is still unknown, although its pathogenesis seems to be involved in the result of natural killer cells, cytotoxic T cells and autoantibodies. Recently, it has been reported that programmed death of cardiac myocytes can be induced by several pathological conditions including infarction and end-stage cardiac failure. However, little is known about the myocardial cell death in myocarditis. In this study, we investigated whether myocardial cell death via apoptosis occurs in the heart tissue with myocarditis.

Since it has been reported that the pathogenesis of the tissue damage in viral myocarditis resembles that in experimental autoimmune myocarditis induced by myosin, we used an experimental model for autoimmune myocarditis induced in Lewis rat with the use of myosin as the antigen. Rats were sacrificed on days 14, 17 and 21 after myosin injection. The tissue specimens were taken from ventricle of the heart.
Mitochondrial Activity and Morphology are Affected by Sphinganine in Neurospora Crassa.
Authors: Gerlach J A , Bart K M , Aaronson L R
Published: July 2020

It has been proposed that sphinganine may function as a natural antifungal barrier in mammals. This sphingoid base is found highly concentrated in epidermis, where it has been documented to inhibit the colonization of pathogenic fungi such as Epidermophyton and Candida. Since Neurospora crassa is sensitive to the effects of sphinganine within the same concentration range as infectious fungi, it is being employed as the model to study the mechanism of sphinganine toxicity in fungal pathogens. With the dramatic increase in fungal mycoses seen in immunocompromised individuals to date, this natural constituent of mammalian epidermis may be employed as a potent, novel antifungal drug.

During this project, radioactive labelling with [3H]sphinganine was employed to observe metabolism of exogenous sphinganine into complex sphingolipids. Transmission electron microscopy analysis was utilized to observe changes in cellular ultrastructure, while fluorescence microscopic techniques were used to assay certain cell functions.

Within 1 hr, exogenous sources of sphinganine are metabolized into dihydroceramides and cerebrosides by the enzymes of complex sphingolipid synthesis.
Changes in the Elemental Composition of Bladder Mucus in Stone and Non-Stone forming Patients following Augmentation Cystoplasty
Authors: Ackerley CA , Tilups A , Khoury AE , Becker LE , Mittleman MW
Published: July 2020

The incidence of bladder stones is increased by 50% following bladder augmentation(l,2). Stones require surgical removal as they are typically too large to pass. A recurrence rate of 19% has been noted(2) necessitating multiple sugical procedures. Etiology of stones in augmented bladders is due to a number of factors including foreign body reactions, metabolic abnormalities, infection and intestinal mucus. In order to determine whether the elemental composition of bladder mucus plays a role in the development of bladder calculi, energy dispersive x-ray spectrometry(EDXS) was done on the mucus from stone and non-stone forming patients. In addition, stones from the same patients were examined and analyzed and the data compared with the composition of the mucus.

Eighteen patients participated in this study, 14 of whom had ileo-cystoplasties and 2 ileo-cecal augments. Two were cloacal extrophy patients where the hind gut was incorporated with the bladder halves. To avoid any foreign body reactions, metal staples were not used in any of the bladder augmentation procedures.
Analysis of Platelet Dense Granules in Storage Pool Deficient Patients
Authors: McKenzie MM , Gunning WT , Smith MR , Lachant NA , Turner JN
Published: July 2020

Prolonged bleeding times may be evident in patients with various conditions. Analysis of platelet function can provide an insight into the cause. Platelets contain substances such as ADP, calcium, epinephrine, and serotonin which are stored in the electron dense or delta granules. Our experience has shown normal platelets to have 4-6 dense granules (Figure 1), which is supported by the literature. The prolonged bleeding times of patients who have less than the normal number of dense granules may be attributed to the lack of adequate factors that aid in the clotting process. These storage pool deficient (SPD) patients are being classified by their low dense granule count. Patients with prolonged bleeding times but normal dense granule counts may need to have their granules evaluated for size and volume (Figure 2).

Whole mounted platelets were placed in the transmission electron microscope (TEM), and negatives were obtained at a magnification of 10,200x. The typical dense granule seen in normal whole mounts is circular.
Ultrastructure of Human Purkinje Fibers in Cases of Sudden Cardiac Death
Authors: Siew S
Published: July 2020

Two fundamental properties of protoplasm: contractility and conductivity, are brought to a high degree of development in muscular tissue. The rhythm of the mammalian heart is initiated and regulated by fibers that have become specialized to conduct the electrical impulse. These fibers comprise the impulse conduction system of the heart, and they are capable of the conduction of an impulse at a faster rate than the rest of the myocardium, whose fibers are specialized for contraction, which has earned them the terminology of “working myocardium”. Conduction tissue has the property of automaticity, which is defined as the ability of a cell to depolarize spontaneously during the diastolic interval and to reach the threshold potential, thus generating an action potential. The conducting cells have a lower internal resistance and a higher conductance than the tension generating cells of the myocardium, which are specialized for contraction. This tissue shows a prepotential rise of the baseline, so that the cells are already partially depolarized.
Ebola Virus Hemorrhagic Fever, Zaire, 1995: an Ultrastructural Study
Authors: Goldsmith C S , Rollin P E , Zhang X H , Peters C J , Zaki S R
Published: July 2020

Ebola and Marburg viruses, members of the family Filoviridae, cause a severe and often fatal hemorrhagic fever. In April and May of 1995, an outbreak of Ebola virus hemorrhagic fever occurred in Kikwit, Zaire, and of 318 known cases, approximately 77% died. The ultrastructural pathology associated with filoviruses has been well described in non-human primates. On the other hand, ultrastructural studies on human tissues have been relatively few, and limited for the most part to examination of the liver. We report here our ultrastructural observations of autopsy tissues from the liver, as well as lung, skin, and testes of infected patients by using both thin section electron microscopy (EM) and immunogold labeling electron microscopy (IEM).

At the hospital in Kikwit, strict barrier precautions were employed to collect tissue specimens. These were diced into small blocks, placed into fixative, and later transferred to phosphate buffer. Specimens were hand-transported to the CDC in Atlanta, gamma-irradiated, and embedded in either Epon-substitute/Araldite for standard EM, or in LR White for IEM.
Transmission Electron Microscopy of Rat Kupffer Cell Activation After Cisplatin Treatment: an in Vivo Study
Authors: Telgenhoff DJ , Aggarwal SK
Published: July 2020

Cisplatin (cis-diamminedichloroplatinum II) is a broad spectrum anti-cancer agent. Its main limitations are its severe toxic side effects. Cisplatin’s major mechanisms of action include inhibition of DNA synthesis by interstrand and intrastrand crosslinking, inhibition of cytokinesis, and macrophage activation. Cisplatin acts through the activation of the immune system by inducing macrophages to form cytoplasmic extensions which seek out and phagocytose tumor cells. More recently, cisplatin has been shown to activate Kupffer cells (macrophages in the liver) by increasing their number and cytoplasmic extensions. Electron microscopic analysis of cisplatin treated rat liver in vivo was performed to examine these extensions in greater detail and relate these to other changes in the liver cells.

Wistar rats (100-130 g) were given intraperitoneal injections of cisplatin (9 mg/kg in 0.9% sodium chloride) over a five day period. Controls were treated with equal amounts of the vehicle of injection. After 9 days the rats were sacrificed. Segments of liver were fixed in 2% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.3).
Cryo-Electron Microscopy of Spiroplasma Virus SpV4
Authors: Chipman PR , Mckenna R , Renaudin J , Baker TS
Published: July 2020

Spiroplasma, a wall-free prokaryote of the class Mollicutes, is host to a small, naked, single-stranded DNA, isometric virus. Spiroplasma virus SpV4 belongs to the Microviridae family, members of which are non-enveloped, have icosahedral capsids, release progeny through a lytic cycle, and contain circular DNA.

Measurements obtained from negatively stained SpV4 particles revealed a nucleocapsid of 27nm in diameter (figure 1). The three-dimensional structure reported here, obtained from unstained particles suspended in a layer of vitreous ice (figure 2), is in agreement with these earlier results, suggesting a 27nm average distance through the nucleocapsid (figure 3). Unreported in earlier studies is the presence of a 6nm, mushroom-shaped protrusion (made up of a stalk, 2.3nm long and 1.3nm wide, and a globular bud of dimensions ≈4.0×4.0×3.7nm) stemming from an ≈1.5nm deep depression at each of the 3-fold icosahedral axes of the virion. A cross section through the longitudinal axis of one protuberance (figure 4) reveals a cylindrical dimple (≈1.0nm in diameter and 2.3nm deep), originating on the axis of the outer surface of the globular bud domain.
Laser Scanning Confocal Microscopic Analysis of Cells Transfected with Genes of Varicella Zoster Virus
Authors: Grose Charles , Hatfield Christopher , Olson Julie , Buranathai Chantee
Published: July 2020

Varicella-zoster virus (VZV) is one of the human herpes viruses. It causes chickenpox in childhood; after chickenpox the virus remains in a latent state in the dorsal root ganglia of the spinal cord. When the virus reactivates in late adulthood, it causes the disease known as shingles or herpes zoster. The VZV genome includes approximately 70 open-reading frames, but only a few of the gene products have been well characterized.

The VZV glycoproteins include gH, gL, gE and gI. The gH:gL complex is an important viral fusogen. Through laser scanning confocal microscopy, we developed an assay to measure VZV-induced fusion and syncytial formation. VZV also encodes a cell surface Fc receptor, glycoprotein gE. VZV gE has previously been shown to display several features common to nonviral cell surface receptors. Attention focused on the ability of VZV gE to undergo receptor-mediated endocytosis. The transient transfection studies demonstrated by confocal microscopy and intemalization assays that VZV gE was endocytosed when expressed in HeLa cells. Endocytosis of gE was shown to be dependent on clathrin-coated vesicle formation within the cells.
Pseudoknot Structures in Retroviral and Bacteriophage Messenger RNA: a Family of Structurally Related RNA Pseudoknots
Authors: Hoffman DW , Du Z , Holland JA , Hansen MR , Wang Y , Giedroc DP
Published: July 2020

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the three-dimensional structure of an RNA pseudoknot with a sequence corresponding to the 5' end region of the gene 32 messenger RNA of bacteriophage T2. NMR results show that the pseudoknot contains two coaxial A-form helical stems connected by two loops. One of the loops consists of a single nucleotide, which spans the major groove of the seven base pair helical stem 2. The second loop consists of 7 nucleotides, and spans the minor groove of stem 1. A three-dimensional model of the pseudoknot that is consistent with the NMR data will be presented, and features that are likely to be important for stabilizing the pseudoknot structure will be described.

A combination of NMR and phylogenetic methods were used to characterize the structural features of RNA pseudoknots that are associated with frameshift and readthrough sites within the retroviral gag-pro messenger RNA. The majority of the retroviral frameshift and readthrough sites were found to be followed by nucleotide sequences that have the potential to form pseudoknots with structures that are remarkably similar to that of the bacteriophage T2 gene 32 mRNA.
Morphology of and Silicon Distribution within the Non-Glandular Trichomes of Soybean
Authors: Paul RN , Elmore CD , Gibson D
Published: July 2020

Three near isolines of soybean [Glycine max (L.) Merr.], glabrous, normal, and dense, were examined by light, scanning electron, and transmission electron microscopy, as well as by energy dispersive x-ray spectroscopy. This was done in order to determine the morphology and possible functions, in addition to conveying insect resistance, of their non-glandular trichomes.

The uppermost fully expanded trifoliate leaf from greenhouse grown juvenile plants was chosen for examination. Fixed tissue was examined by LM, TEM and SEM as previously described. Some tissue was prepared for energy dispersive spectrometry by fixing in glutaraldehyde but omitting osmium. The tissue was then dehydrated, critical point dried, and coated with carbon. Si x-ray maps were made on the adaxial and abaxial leaf surfaces of all three biotypes.

LMs of Spurr embedded toluidine blue stained semithin sections of normal (Fig. 1) and glabrous (Fig. 2) trichomes appear similar in structure.
Immunolocalization of a Phloem Protein in Luffa Cylindrica
Authors: Chang Y Y , Chuang H B , Chen Y R
Published: July 2020

P-proteins are group of proteins that express specifically in the sieve elements or parenchymatous cell of phloem tissues. They are filamentous, spherical, tubular, crystalline and amorphous in shape and their ontogenesis varied from species to species. Some of them are plant lectins and their coding genes have been sequenced. In the previous study, a 24 kDa phloem protein was obtained from phloem exudate of Luffa cylindrica fruits and it was immunofluoresciently located in the bicollateral phloem tissues of vascular bundles. In the present study, the intracellular localization of 24 kDa p-protein was examined with colloidal-gold immunolabelling.

Fruits of L. cylindrica were harvested for study. The outer parts of fruits containing exocarp and mesocarp were firstly cut into small cubes in dimensions of 2 x 2 x 6 mm, prefixed in 0.1 M phosphate buffer containing 4 % aldehyde mixture of paraformaldehyde and glutaraldehyde (3:1) for 4 h and washed with distilled water. The washed cubes were then trimmed into 1 mm cubes and postfixed in OSO4 for 2 h, dehydrated in a graded ethanol series and embedded in Spurr's resin.
An Endophytic Fungus from Cephalotaxus: Phoma SP. which Produces Anti-Fungal Substances
Authors: Li J Y , Strobe G , Hess W M , Ford E
Published: July 2020

Various species of endophytic fungi produce a variety of potentially useful new Pharmaceuticals in host tissue of different plants. As an example, the anti-cancer drug, taxol is produced by several species of fungi isolated from various host species.

A Phoma was isolated from the inner bark of Cephalotaxus fortunei growing near Hangzhou, China. After 7-10 days of incubation at 23C cultures were hyphal tipped and transferred to PDA and gamma-irradiated carnation leaves. Cultures which produced bioactive substances were studied further. This Phoma sp. is particularly active against Pythium ultimum. Another endophytic Phoma sp. isolated from Taxus wallachiana also makes antimetabolite compounds. Presumably these endophytic Phoma spp. exist in a symbiotic relationship with various tree species contributing substances that inhibit or destroy invading pathogenic fungi and bacteria.

The fungus produces globose dark brown, thin-walled pycnidia which are semi-immersed in carnation leaf pieces (Fig. 1). Cream-colored conidia (Fig. 2), which average 4.5-5 × 1.75-3 μm are produced in pycnidia with a single ostiole normally obscured by a gelatinous mass (Fig. 3), which is characteristically not evident on old pycnidia (Fig. 4). Conidia are formed enteroblastically from discrete phialidic conidiogonous cells attached directly to the pycnidial wall. Sclerotia (ca. 1.5-2 mm) are also produced on PDA.
Ceratopteris is a Useful Model Genetic System for Studying Plant Meristem Development.
Authors: Sherman D , Banks J
Published: July 2020

Most tissues of a plant are derived from meristems that reside at the tips of the shoot and root. To identify genes that are involved in the organization and in the coordination of cell division and differentation in the meristem, mutations that affect meristem development have been sought. Several mutations that affect meristem development have been characterized in Arabidopsis and maize; however, the angiosperm meristem is small, inconspicuous and difficult to characterize in a non-destructive way. Gametophytes of the fern Ceratopteris richardii have a meristem that is simple, small and conspicuous and is an ideal system for studying meristem development. In this study, the meristems of wild-type and various mutant gametophytes of Ceratopteris are described using cold stage SEM of hydrated gametophytes.

The haploid gametophytes of the fern Ceratopteris are either male or hermaphroditic and are easily distinguished by size and shape as well as by type of sex organ produced. Hermaphrodites form a distinct meristem; newly divided cells of this meristem have only four possible cells fates: they may differentiate as antheridia, the sperm-forming organs; differentiate as archegonia, the egg-forming organs; enlarge to contribute to the growing two-dimensional sheet of cells; or remain within to maintain the meristem (Fig. 1; an=antheridia; ar=archegonia). Male gametophytes lack a meristem and are thus much smaller than hermphrodites. Almost all cells of the male differentiate as antheridia, the sperm-forming organs (Fig. 2). Because the gametophytes of Ceratopteris are small (<3 mm), conspicious, free-living, and haploid, it is very simple to select mutations that affect the sex of the gametophyte as well the meristem.
The Role of Scanning Electron Microscopy in Taxonomic Studies of Freshwater Bryozoans (Ectoprocta: Phylactolaemata)
Authors: Wood T S , Taylor C A
Published: July 2020

Bryozoans are among the most common multicellular animals that attach to submerged surfaces in fresh waters. Zooids of the colony capture and digest suspended food particles; they also produce distinctive asexual buds called statoblasts. Measuring 0.35 to nearly 1 mm in diameter, statoblasts have a chitinous exterior and are the only truly hard parts of the bryozoan colony. Like the mastax of rotifers or mouthparts of midge larvae, statoblasts show a variety of taxonomically significant features. Scanning electron microscopy reveals clear patterns in statoblast surface topography that suggest many more species than the 60 or so normally recognized.

Statoblast surface features were first used to distinguish species of the genus Fredericella. The European F. sultana, with a smooth statoblast surface, had been assumed to occur worldwide. SEM micrographs showed the statoblast surface of New World Fredericella to be finely pitted, identical to that of F. indica in India (Figure 1). Another Fredericella species, not yet named, is distinguished only by its highly rugose statoblast surface (Figure 2). Such features are retained through generations of laboratory rearing under various controlled conditions.
Scanning Electron Microscopic Study of the Eggs of the Warthog Louse (Haematopinus Phacochoeri)
Authors: Baker C , Green ED
Published: July 2020

The large eggs of Haematopinus phacochoeri are found attached to the long dorsal mane bristles of the diurnal warthog. The eggs are generally exposed to great environmental stresses such as excessive sunlight and temperature as well as the occasional plunge under water or mud during grooming. This investigation was therefore undertaken to determine how the eggs of H. phococoeri are adapted to tolerate the various environmental changes it is constantly exposed to. To our knowledge no other SEM study on the eggs of this species has been performed.

Specimens still attached to the bristles were fixed in 70% ethanol, dehydrated and ultrasonically cleaned. Some eggs were longitudinally sectioned with a razor blade to expose the chorionic layers. The eggs were critical point dried in liquid CO2, mounted and viewed by means of a Leica Stereoscan 420 scanning electron microscope.

The general structure of the shell consists of two layers of chorion, i.e. the endo-and exochorion. These two layers are attached at the pre-formed line of weakness at the operculum and again near the hydropyle. Elsewhere these two layers are completely separated by the respiratory layer.
A Transmission Electron Microscopy Study and Viability Evaluation of the Effect of 2450 MHz Microwaves on Candida albicans.
Authors: Melgoza C , Sepúlveda J , Moreno M , Rodríguez M A
Published: July 2020

Microwaves of 2450 MHz have been used as a heating procedure in food technology, tissue processing for histological studies (1), in medicine (2) and as a sterilization agent for medical devices (3). Experiments were carried out exposing yeast cells of Candida albicans suspended in growth media to different times of radiation at 750 watts in a commercial microwave oven. Batches of 5 tubes containing the cells suspension were radiated from 15 seconds to 3 minutes and colony counts were done after exposure. Viability ceased totally after one minute radiation. Samples were obtained from unexposed controls and tubes radiated for 15, 30, 45 and 60 seconds, centrifuged and the pellets fixed in 1.5% potasium permanganate. After embbeding in Epon, thin sections were obtained and stained with uranyl acetate. Micrographs were taken with a Zeiss EM-109 electron microscope. Cells showed alteration of internal membranes at early times, and later changes indicative of cytoplasmic coagulation and organelle disorganization were seen. At 15 seconds mitochondrial matrix showed alterations followed by damage of its membranes.
Characterization of Ustilago Hordei Fimbriae Using Scanning Transmission Electron Microscopy and Immunocytochemistry
Authors: Henry Caroll E , Salaam TL , Steward-Clark E , Craig Joyce , Reynolds Lennell
Published: July 2020

Sporidia of Ustilago hordei produce surface fimbriae which are important in conjugation and pathogenicity. This work focuses on fimbrial origin and production using transmission electron microscopy (TEM) and immunocytochemistry.

Wild type I4A sporidial cells cultured to log phase with rotary shaking in yeast extract glucose (YEG) growth for 48 h. at 21° C, were harvested by centrifugation at 8000 rpm, placed on formvar coated grids, negatively stained with 2% uranyl acetate and photographed in the JEOL 1200 STEM. Some cells were prepared for sectioning by fixation with gluteraldehyde and cacodylate buffer, post fixed in osmium tetroxide, dehydrated and embedded in epoxy and stained with uranyl acetate. The remainder of the cells were sheared in a blender to remove fimbriae. The defimbriated cells and 1 ml. of fimbrial suspension were presented to TEM. The rest of the fimbrial suspension was centrifuged at 30,000 rpm and he fimbrial pellet protein concentration was determined to be 1.345 nm. as assayed by UV adsorption.
Studies on the Dynamic Localization of GFP-Myosin During Cytokinesis in Live Cells
Authors: Sabry James , Moores Sheri , Ryan Shannon , Zang Ji-Hong , Spudich James A
Published: July 2020

Cell division is thought to be powered by the constriction of an actomyosin containing contractile ring found transiently in the cleavage furrow. Conventional myosin II plays a fundamental role in this process of cytokinesis where, in the form of a multimeric complex known as the bipolar thick filament, it is thought to be the molecular motor that generates the force necessary to cause ring constriction.

In order to study the dynamics of this protein in the dividing cell, we have made a fusion protein of the green fluorescent protein (GFP) and the amino terminus of the Dictyostelium myosin heavy chain (GFP-myosin), and imaged the location of this protein in dividing Dictyostelium cells were it is the only myosin II present in the cell. The addition of GFP does not compromise the functioning of the myosin motor as evidenced by the fact that purified GFP-myosin has solution ATPase and in vitro motility kinetics similar to that of non-labelled myosin. In addition, GFP-myosin fully complements the myosin null mutation for both development and cytokinesis in suspension suggesting that GFP-myosin acts as a regulated motor when expressed in cells.
Alterations in the Molecular Interaction of Bcl-2 and Bax During Apoptosis Assessed Using Fluroescence Resonance Energy Transfer (FRET) Microscopy and Green Fluorescent Protein (GFP)-Bax and Blue Fluorescent Protein (BFP)-Bcl-2 Expressing Proteins
Authors: Mahajan N , Herman B
Published: July 2020

Apoptosis or programmed cell death, is a mechanism of cellular demise which is believed to play a role in many physiological processes, and which when defective, can contribute to the pathogenesis of cancer. Apoptosis is stimulated in cells by the p53 tumor suppresser, Bax and El A proteins and inhibited by overexpression of Bcl-2 and adenovirus E1B 19 kDa oncoproteins. A role for altered apoptosis in cancer comes from recent reports which have documented that inactivation of p53 (which promotes apoptosis) and/or overexpression of bcl-2 (which inhibits apoptosis) occurs in numerous cancers. Recent work from our laboratory has shown that inactivation of p53 (either by physical complex formation between p53 and Human Papillomavirus (HPV) type 16- or 18- E6 protein or by mutation of p53), is associated with increased expression of bcl-2 in cervical carcinoma cells. The combination of inactive p53 and increased expression of bcl-2 may lead to inhibition of apoptosis and thereby contribute to the development or progression of cervical cancer.
Spectral Imaging of Chromogenic Dyes in Cytological Specimens
Authors: Macville Merryn , Speel Ernst-Jan , Soenksen Dirk , Hopman Ton , ThomasRied
Published: July 2020

Recently, spectral imaging has been successfully applied to 24-color fluorescence in situ hybridization (FISH), and it has evolved into a new powerful method for the analysis of structural and numerical chromosomal aberrations on metaphase spreads (spectral karyotyping) For cytological specimens it is often impossible to use fluorescence microscopy because of (fixation-induced) auto-fluorescence or prior cytological staining. Also, re-examination of archived fluorescent specimens is hampered by fading. However, the need for multi-parameter cytochemical analysis remains when rare or unique material is to be studied in research or clinical diagnosis. Multi-color bright-field microscopy using enzyme precipitates has become feasible for in situ hybridization as well as immunohistochemical detection. Conventional transmission microscopy optics have allowed up to three targets to be detected simultaneously. In parallel to 24-color FISH, we explored the potential of spectral imaging to increase the number of parameters to be analyzed in bright-field microscopy.
Measurement of the Dissociation Time Constant of Plasma Membrane Bound Protein Domains Using GFP Fusion Tags
Authors: Teruel Mary , Oancea Elena , Stauffer Thomas , Meyer Tobias
Published: July 2020

We have previously shown that the spatial dynamics of GFP-tagged proteins can be investigated by locally enhancing the fluorescence of GFP using a short UV-laser pulse. 1 We have since developed photobleaching and photoenhancement methods to study binding parameters of GFP-tagged protein domains in intact cells. Here we present an analysis procedure which uses either photobleaching or photoenhancement measurements to determine simultaneously (1) the lateral diffusion coefficient and (2) the dissociation time constant defined for a plasma membrane associated, GFP-tagged protein. The dissociation time constant is defined as the time required for the dissociation of 63% of bound protein and is a functionally relevant parameter related to the binding strength. High affinity interactions are associated with a slow dissociation time constant and low affinity interactions with a fast dissociation time constant. The dissociation time constant of a signaling protein also imposes a critical limit on the cellular response time for signal transduction.
Studies on the Green Fluorescence Protein Marked Autographa Californica Multiple Nucleopolyhedrovirus in Trichoplusia ni Larvae.
Authors: Brownwright AJ , Barrett JW , Palli SR
Published: July 2020

We have investigated the infection process of Green Fluorescence Protein marked Autographa Californica multiple nucleopolyhedrovirusCAcMNPV-GFP) under both light and electron microscopes. Enveloped virus particles were observed in the nucleus of columnar epithelial cells of the midgut 24 hours after feeding Trichoplusia ni larvae with AcMNPV-GFP infected freeze-dried larvae. by this time enveloped virus particles were also observed in the plasma membrane reticular system(PMRS) of midgut epithelial cells and nuclei of the tracheoblasts that are present in the connective tissue of the midgut. by 60 hours post feeding, tissues such as fat body and epidermis were showing enveloped virus particles in their nuclei while the the midgut epithelial cells were now largely devoid of virus.

Based on these results we propose that enveloped virions released from occlusion bodies in the lumen enter columnar epithelial cells and replicate in the nucleus. At the same time some of the virions enter the PMRS and get quick access to tracheoblasts present in the midgut connective tissue and thereafter to hemocytes present in the haemolymph.
Employment of a Bioreactor Vessel to Simulate Elements of Microgravity During Early Chick Heart Development
Authors: Norton WN , Wiens D
Published: July 2020

Formation of the chick heart is initiated when paired regions of the mesoderm migrate to a specific region in the primitive head. Certain cells eventually form a pair of endocardiac tubes that become the lining of the heart, while the remaining precardiac mesoderm ultimately differentiates into the myocardium. Fibronectin is suspected as a crucial component of the migratory process. Very few investigations have been conducted on the relationship between cell motility and microgravity.

The primary objectives of this investigation were to determine the effect of altered gravity on the production and distribution of fibronectin, an extracellular matrix glycoprotein, during embryonic development of the chick heart, and to ascertain the extent to which these alterations affect myogenesis or morphogenesis. A microgravity bioreactor vessel, originally designed by NASA as a low-shear culture system, was employed to culture the cellular expiants in a simulated microgravity environment. Fertile, White-Leghorn chicken eggs were incubated at 38°C for 32 hours in a humidified egg incubator.
The Effect of Tgfß-2 on Inner Ear Development: Light and Electron Microscopy Observations
Authors: Friedman R , Paradies N , Wert S , Doetschman T , Cardell EL
Published: July 2020

Transforming growth factor beta (TGFß) genes are linked to a variety of developmental processes and are the subject of in vivo and in vitro transgene research studies. We are evaluating TGFß-2 effects on mouse inner ear development, with emphasis on the cochlear duct (CD), by comparing plastic sections of intact inner ears from developmental day (D) 16.5,18.5 and 19.5 littermates with wildtype (+/+), heterozygous (+/−) and mutant (−/−) TGFß-2 genotypes as determined by polymerase chain reaction analysis of tail digests. Auditory and vestibular organs of all D16.5 mice appear similar: membranous labyrinth epithelium varies from simple cuboidal/low columnar to pseudostratified/stratified columnar. Surrounding mesenchyme varies in cell density regionally, the most cellular mesenchyme underlies areas of sensory epithelium. Sparse mesenchymal cell distribution in the vestibule and basal CD indicates sites of perilymph channel formation. The spiral and vestibular ganglia and their unmyelinated fibers are prominent. Otoconia and hair cells are present in the utricle (U) and saccule (S) maculae; hair cells are less easily identifiable in the CD.
An Electron Microscopic Study of Developing Synapses in Facial and Hypoglossal Motor Nuclei of the Brazilian Opossum.
Authors: Pepper TM , Swanson JJ , Kuehl-Kovarik MC , Jacobson CD
Published: July 2020

Previously, we have shown the apparent development of synapses utilizing immunohistochemistry (IHC) for synapse-associated proteins in the facial and hypoglossal motor nuclei of the Brazilian opossum. This study suggests that synaptogenesis is delayed in the facial motor nucleus (FMN) as compared to the hypoglossal motor nucleus (HMN). In the present study we plan to confirm and extend these findings at the electron microscopic (EM) level.

We have examined the ultrastructure of the developing FMN from animals 5 to 25 days of postnatal age (PN). The specific nuclei were identified using methylene blue stained 150 μm thick vibratome cut sections. The FMN and HMN were then dissected out for processing, guaranteeing that visualization at the EM level would be confined to areas specific to the nuclei of interest.

Initial analysis of the FMN indicates a marked increase of detectable synapses between 5 and 15PN.
Effects of Transforming Growth Factor-β1 on Decorin Expression by Undifferentiated Osteoblastic Cells
Authors: Bailey GW , Dimlich RVW , Alexander KB , McCarthy JJ , Pretlow TP , Yamada T , Kubushiro N , Shigemasa K , Ikeda T , Takagi M
Published: July 2020

Decorin is the predominant proteoglycan isolated from bone of several animal species. Bone matrix decorin appears to bind transforming growth factor β (TGF-β) and enhances its bioactivity. TGF-β is stored in bone matrix in abundant amounts and modulates the synthesis of bone matrix proteins by osteoblasts. Thus it appears to play a role in regulation of bone formation during the bone remodeling process. The effect of TGF-β on decorin expression in bone cells has been evaluated in murine osteoblastic cells, but the results are divergent depending on the experimental conditions and cell types used. The present study investigated the effect of TGF-βl on the expression of decorin mRNA in two clonal rat osteoblastic cell lines with different stages of differentiation, ROS-C26 (C26) and ROS-C20 (C20); C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; C20 is a more differentiated osteoblastic cell line.
Horse Radish Peroxidase Labelled Oligonucleotides and Tyramide Signal Amplification for Fluorescence in Situ Hybridization to Low Abundant Cytokine Mrnas
Authors: Corput Mariette van de , Gijlswijk Rob van , Bobrow Mark , Erickson Tom , Dirks Roel , Raap Ton
Published: July 2020

In recent years, Tyramide Signal Amplification (TSA) has gained acclaim as a very sensitive detection method for immunocytochemsitry and fluorescence in situ hybridization (FISH). To maximally exploit the great signal generation capacity of TSA in mRNA-FISH, minimizing signals emanating from non-specifically bound nucleic acid probe becomes of prime importance, because a specificity check of the signals observed in the cytoplasm is virtually impossible. We reasoned that utilization of synthetic oligonucleotides (ONTs) in stead of commonly used cDNAs or cRNAs would diminish non-specific probe binding and that direct Horse Radish Peroxidase (HRP) labelling of ONTs and TSA would enable their in situ detection.

This approach was first tested in metaphase DNA-FISH using chromosome-specific repeats as targets. Using bifunctional crosslinking chemistry and HPLC, 5’-hexylamino oligonucleotides for chromosome specific simple satellite and alphoid sequences were conjugated to HRP and purified. Following 15 - 20 min of situ hybridization of a single HRP-ONT probe to metaphase chromosomes and a direct flurochrome-tyramide detection step, such repeat targets could be visualized with high specificity and excellent signal-to noise ratio.
Comparative Genomic Hybridization to Dna Microarrays
Authors: Pinkel D , Segraves R , Sudar D , van Vliet L , Clark S , Chen C , Zhai Y , Gray JW , Albertson D G
Published: July 2020

Comparative genomic hybridization (CGH), which involves the simultaneous hybridization of differentially labeled total genomic DNA from test cells and reference normal cells to metaphase chromosomes, has been used extensively to screen tumor genomes for regions of DNA sequence copy number variation. Analysis of these hybridizations requires quantitative analysis of the ratio of intensities of the fluorescent hybridization signals as a function of position along the chromosomes, which basically serve as a convenient genetic map. The ratios need to be measured very accurately since changes of about ± 20% from the average for the genome indicate important genetic events. Widespread use of CGH over the past several years has identified numerous regions of the genome that may contain currently unknown cancer genes. For example, regions of increased copy number may indicate sites of oncogenes, while regions of copy number decrease relative to average for the genome may signify the presence of a tumor suppressor gene.