scholarly journals Outbreak of cryptosporidiosis in African penguins Spheniscus demersus

2020 ◽  
Vol 140 ◽  
pp. 143-149
Author(s):  
R Hurtado ◽  
NJ Parsons ◽  
TA Gous ◽  
Sv der Spuy ◽  
R Klusener ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Signs ◽  
Necrotic Enteritis ◽  
Rehabilitation Center ◽  
Transmission Electron ◽  
Petechial Hemorrhage ◽  
Spheniscus Demersus ◽  
Undigested Food ◽  
African Penguin

Cryptosporidium spp. are parasitic intracellular protozoa that infect the digestive, respiratory, and urinary tracts of vertebrates. The disease affects many different avian species across all continents, and >25 species and genotypes of Cryptosporidium have been documented infecting birds. We report on an outbreak of cryptosporidiosis in African penguin Spheniscus demersus chicks admitted to a rehabilitation center in South Africa from February 2012 to October 2013. Eighteen cases were confirmed through histopathology. The most frequent clinical signs were regurgitation (78%), dyspnea (72%), decreased weight gain or weight loss (72%), and lethargy (50%). Clinical signs began 8-46 d after hatching or admission (median: 13 d), and death followed 1-41 d after the onset of clinical signs (median: 13.5 d). The most frequent necropsy findings were stomach distended with undigested food or gas (78%), mildly reddened lungs (56%), spleen petechial hemorrhage (44%), and kidney congestion (39%). The most frequent histopathological findings were necrotic bursitis (89%), necrotic enteritis (83%), and bursal atrophy (67%). Small round or oval basophilic bodies (3-5 µm diameter) consistent with Cryptosporidium sp. were closely associated with the surface of the epithelial cells or in the lumen of the bursa (89%), large intestine (61%), small intestine (44%), trachea (22%), and ventriculus (6%). Transmission electron microscopy of 1 case confirmed that these organisms were Cryptosporidium sp. To our knowledge, this is the first report of cryptosporidiosis in penguins, raising concern of the potential implications for the conservation of these species.

scholarly journals Clostridium perfringens produces an adhesive pilus required for the pathogenesis of necrotic enteritis in poultry

2021 ◽  
Author(s):  
D. Lepp ◽  
Y. Zhou ◽  
S. Ojha ◽  
I. Mehdizadeh Gohari ◽  
J. Carere ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Surface ◽  
Clostridium Perfringens ◽  
Direct Evidence ◽  
Necrotic Enteritis ◽  
Null Mutant ◽  
Transmission Electron ◽  
Mutant Strains ◽  
Important Disease

Clostridium perfringens Type G strains cause necrotic enteritis (NE) in poultry, an economically important disease that is a major target of in-feed antibiotics. NE is a multifactorial disease, involving not only the critically-important NetB toxin, but also additional virulence and virulence-associated factors. We previously identified a C. perfringens chromosomal locus (VR-10B) associated with disease-causing strains that is predicted to encode a sortase-dependant pilus. In the current study, we sought to provide direct evidence for the production of a pilus by C. perfringens and establish its role in NE pathogenesis. Pilus structures in virulent C. perfringens strain CP1 were visualized by transmission electron microscopy (TEM) of immuno-gold labelled cells. Filamentous structures were observed extending from the cell surface in wild-type CP1, but not from isogenic pilin-null mutant strains. In addition, immuno-blotting of cell surface proteins demonstrated that CP1, but not the null mutant strains, produced a high molecular weight ladder-like pattern characteristic of a pilus polymer. Binding to collagen types I, II and IV was significantly reduced (Tukey’s; p<0.01) in all three pilin mutants compared to CP1, and could be specifically blocked by CnaA and FimA antisera, indicating that these pilins participate in adherence. Furthermore, both fimA and fimB null mutants were both severely attenuated in their ability to cause disease in an in vivo chicken NE challenge model. Together, these results provide the first direct evidence for the production of a sortase-dependant pilus by C. perfringens, and confirm its critical role in NE pathogenesis and collagen-binding. Importance In necrotic enteritis (NE), an intestinal disease of chickens, Clostridium perfringens cells adhere tightly to damaged intestinal tissue, but the factors involved are not known. We previously discovered a cluster of C. perfringens genes predicted to encode a pilus, a hair-like bacterial surface structure commonly involved in adherence. In the current study, we have directly imaged this pilus using transmission electron microscopy (TEM). We also show that inactivation of the pilus genes stops pilus production, significantly reducing the bacterium's ability to bind collagen and cause disease. Importantly, this is the first direct evidence for the production of a sortase-dependant pilus by C. perfringens, revealing a promising new target for developing therapeutics to combat this economically important disease.

scholarly journals Susceptibility of Exopalaemon carinicauda to the Infection with Shrimp Hemocyte Iridescent Virus

2019 ◽  
Author(s):  
Xing Chen ◽  
Liang Qiu ◽  
Hailiang Wang ◽  
Peizhuo Zou ◽  
Xuan Dong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Symptoms ◽  
Histopathological Examination ◽  
Clinical Signs ◽  
Taqman Probe ◽  
Exopalaemon Carinicauda ◽  
Hematopoietic Tissue ◽  
Iridescent Virus ◽  
Transmission Electron

In this study, ridgetail white prawns Exopalaemon carinicauda were infected per os with debris of Shrimp hemocyte iridescent virus (SHIV)-infected Penaeus vannamei and via intramuscular injection (im) with raw extracts of SHIV. The infected E. carinicauda showed obvious clinical symptoms, including weakness, empty gut and stomach, pale hepatopancreas, and partial death with cumulative mortality of (50.0&plusmn;26.5)% and (76.7&plusmn;18.3)%, respectively. Results of TaqMan probe based real-time quantitative PCR showed that the moribund and survival individuals with clinical signs of infected E. carinicauda were SHIV-positive. Histological examination showed that there were dark eosinophilic inclusions, of which some were surrounded with or contained tiny basophilic staining, and pyknosis in cytoplasm of hemocytes in the hepatopancreatic sinus, hematopoietic cells, and cuticular epithelium, etc. Positive hybridization signals were observed in stomach, hematopoietic tissue, cuticular epithelium, and hepatopancreatic sinus of infected prawns from both per os and im groups, according to the results of in situ DIG-labeling-loop-mediated DNA Amplification (ISDL). Transmission electron microscopy of ultrathin sections showed that icosahedral SHIV particles existed in hepatopancreatic sinus and gills of the infected E. carinicauda of the per os group. The viral particles were also observed in the hepatopancreatic sinus, gills, pereiopods, muscles, and uropods of the infected E. carinicauda from the im group. The assembled virions mostly distributed outside of the assembling area near cellular membrane of infected cells, which were with envelope and about 150 nm in diagonal diameter. The results of molecular biological tests, histopathological examination, ISDL, and transmission electron microscopy confirmed that E. carinicauda is one of the susceptible hosts of SHIV. This study also reminded that E. carinicauda showed some degree of tolerance to the infection with SHIV per os challenge mimicking natural pathway.

scholarly journals Ocular Histopathological Findings in Semi-Domesticated Eurasian Tundra Reindeer (Rangifer tarandus tarandus) with Infectious Keratoconjunctivitis after Experimental Inoculation with Cervid Herpesvirus 2

Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1007
Author(s):  
Javier Sánchez Romano ◽  
Karen K. Sørensen ◽  
Anett K. Larsen ◽  
Torill Mørk ◽  
Morten Tryland
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rangifer Tarandus ◽  
Mononuclear Cells ◽  
Clinical Signs ◽  
Histopathological Analysis ◽  
Rangifer Tarandus Tarandus ◽  
Transmission Electron ◽  
Experimental Inoculation ◽  
Infectious Keratoconjunctivitis

Infectious keratoconjunctivitis (IKC) is a common transmissible ocular disease in semi-domesticated Eurasian tundra reindeer (Rangifer tarandus tarandus). In large outbreaks, IKC may affect tens of animals in a herd, with the most severe cases often requiring euthanasia due to the destruction of the affected eyes and permanent blindness. An experimental inoculation with cervid herpesvirus 2 (CvHV2), alone or in combination with Moraxella bovoculi, demonstrated that CvHV2 has the ability to cause clinical signs of IKC in previously unexposed reindeer. Tissues collected from upper and lower eyelids, lacrimal gland and cornea, were processed for light and transmission electron microscopy. Histopathological analysis of the eyes inoculated with CvHV2 showed widespread and severe pathological findings. Mucosal tissues from these eyes showed fibrinous and purulent exudates, hyperemia, hemorrhages, necrosis, vascular thrombosis, vascular necrosis, infiltration of mononuclear cells and neutrophils, and lymphoid follicle reaction, which matches the described histopathology of IKC in reindeer. Characteristic alpha-herpesvirus particles matching the size and morphology of CvHV2 were identified by transmission electron microscopy in the conjunctival tissue. The quantification of viral particles by qPCR revealed high copy numbers of viral DNA in all CvHV2 inoculated eyes, but also in the non-inoculated eyes of the same animals. The histopathology of eye tissues obtained from the CvHV2 inoculated reindeer and the lack of inflammation from bacterial infection, together with the detection of CvHV2 DNA in swabs from the inoculated and non-inoculated eyes of the same animals, verified that CvHV2 was the primary cause of the observed histopathological changes.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Comparative Microstructures of Ion Milled and Electrochemically Thinned Composite Materials

1974 ◽  
Vol 32 ◽  
pp. 546-547
Author(s):  
R.R. Russell
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Composite Materials ◽  
Great Difficulty ◽  
Ion Milling ◽  
Transmission Electron ◽  
Ion Damage ◽  
Intermetallic Composite

Transmission electron microscopy of metallic/intermetallic composite materials is most challenging since the microscopist typically has great difficulty preparing specimens with uniform electron thin areas in adjacent phases. The application of ion milling for thinning foils from such materials has been quite effective. Although composite specimens prepared by ion milling have yielded much microstructural information, this technique has some inherent drawbacks such as the possible generation of ion damage near sample surfaces.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Tumor Diagnosis

1982 ◽  
Vol 40 ◽  
pp. 262-265
Author(s):  
Bruce Mackay
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Diagnosis ◽  
Light Microscopy ◽  
Clinical Examination ◽  
Ultrastructural Study ◽  
Diagnostic Procedures ◽  
Specific Diagnosis ◽  
Transmission Electron ◽  
Microscopic Diagnosis

The broadest application of transmission electron microscopy (EM) in diagnostic medicine is the identification of tumors that cannot be classified by routine light microscopy. EM is useful in the evaluation of approximately 10% of human neoplasms, but the extent of its contribution varies considerably. It may provide a specific diagnosis that can not be reached by other means, but in contrast, the information obtained from ultrastructural study of some 10% of tumors does not significantly add to that available from light microscopy. Most cases fall somewhere between these two extremes: EM may correct a light microscopic diagnosis, or serve to narrow a differential diagnosis by excluding some of the possibilities considered by light microscopy. It is particularly important to correlate the EM findings with data from light microscopy, clinical examination, and other diagnostic procedures.

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