Virus-Like Particles in an Ultra-Oligotrophic Lake on Vancouver Island, British Columbia

1990 ◽  
Vol 47 (4) ◽  
pp. 725-730 ◽  
Author(s):  
M. Emilia Klut ◽  
John G. Stockner
Keyword(s):  
British Columbia ◽  
Morphological Changes ◽  
Vancouver Island ◽  
Host Cells ◽  
Variable Size ◽  
Free Living ◽  
Virus Like Particles ◽  
Transmission Electron ◽  
Dense Matrices ◽  
Virogenic Stroma

Transmission electron microscopy (TEM) seasonal studies of concentrated water samples from Sproat Lake, Vancouver Island, British Columbia, revealed numerous polygonal virus-like particles of variable size (60–200 nm). These particles (ca. 107/mL) were either free-living or associated with host picoplankters. Negative staining of living samples provides clear evidence of early stages of phage–picoplankton interactions. These phages display a six-sided head (ca. 90 nm dia.) with a distinct appendage (ca. 200 nm) or striated tail (ca. 130 nm). Viruses with dense matrices, deprived of envelopes or occurring as empty shells were found in the marginal area of invaded cells. Morphological changes such as invagination of the photosynthetic lamellae with the appearance of 'virogenic stroma' or with disruption of the cell membrane and the cell wall are described. Comments on the possible functional significance of viral agents in the biology and ecology of host cells are presented.

scholarly journals Interaction of Pasteurella multocida with Free-Living Amoebae

2005 ◽  
Vol 71 (9) ◽  
pp. 5458-5464 ◽  
Author(s):  
Matthew J. Hundt ◽  
Carmel G. Ruffolo
Keyword(s):  
Pasteurella Multocida ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Free Living ◽  
Fowl Cholera ◽  
Transmission Electron ◽  
Membrane Bound ◽  
Green Fluorescent ◽  
First Time

ABSTRACT Pasteurella multocida is a highly infectious, facultative intracellular bacterium which causes fowl cholera in birds. This study reports, for the first time, the observed interaction between P. multocida and free-living amoebae. Amoebal trophozoites were coinfected with fowl-cholera-causing P. multocida strain X-73 that expressed the green fluorescent protein (GFP). Using confocal fluorescence microscopy, GFP expressing X-73 was located within the trophozoite. Transmission electron microscopy of coinfection preparations revealed clusters of intact X-73 cells in membrane-bound vacuoles within the trophozoite cytoplasm. A coinfection assay employing gentamicin to kill extracellular bacteria was used to assess the survival and replication of P. multocida within amoebae. In the presence of amoebae, the number of recoverable intracellular X-73 cells increased over a 24-h period; in contrast, X-73 cultured alone in assay medium showed a consistent decline in growth. Cytotoxicity assays and microscopy showed that X-73 was able to lyse and exit the amoebal cells approximately 18 h after coinfection. The observed interaction between P. multocida and amoebae can be considered as an infective process as the bacterium was able to invade, survive, replicate, and lyse the amoebal host. This raises the possibility that similar interactions occur in vivo between P. multocida and host cells. Free-living amoebae are ubiquitous within water and soil environments, and P. multocida has been observed to survive within these same ecosystems. Thus, our findings suggest that the interaction between P. multocida and amoebae may occur within the natural environment.

scholarly journals Novel Parachlamydia acanthamoebae Quantification Method Based on Coculture with Amoebae

2008 ◽  
Vol 74 (20) ◽  
pp. 6397-6404 ◽  
Author(s):  
Junji Matsuo ◽  
Yasuhiro Hayashi ◽  
Shinji Nakamura ◽  
Marie Sato ◽  
Yoshihiko Mizutani ◽  
...  
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Vero Cells ◽  
Host Cells ◽  
Human Pathogens ◽  
Free Living ◽  
Infectious Dose ◽  
Quantification Method ◽  
Transmission Electron ◽  
Dilution Curves

ABSTRACT Parachlamydia acanthamoebae, belonging to the order Chlamydiales, is an obligately intracellular bacterium that infects free-living amoebae and is a potential human pathogen. However, no method exists to accurately quantify viable bacterial numbers. We present a novel quantification method for P. acanthamoebae based on coculture with amoebae. P. acanthamoebae was cultured either with Acanthamoeba spp. or with mammalian epithelial HEp-2 or Vero cells. The infection rate of P. acanthamoebae (amoeba-infectious dose [AID]) was determined by DAPI (4′,6-diamidino-2-phenylindole) staining and was confirmed by fluorescent in situ hybridization. AIDs were plotted as logistic sigmoid dilution curves, and P. acanthamoebae numbers, defined as amoeba-infectious units (AIU), were calculated. During culture, amoeba numbers and viabilities did not change, and amoebae did not change from trophozoites to cysts. Eight amoeba strains showed similar levels of P. acanthamoebae growth, and bacterial numbers reached ca. 1,000-fold (109 AIU preculture) after 4 days. In contrast, no increase was observed for P. acanthamoebae in either mammalian cell line. However, aberrant structures in epithelial cells, implying possible persistent infection, were seen by transmission electron microscopy. Thus, our method could monitor numbers of P. acanthamoebae bacteria in host cells and may be useful for understanding chlamydiae present in the natural environment as human pathogens.

Ultrastructural Study of Rat Colon Following Psyllium Ingestion

1985 ◽  
Vol 43 ◽  
pp. 580-581
Author(s):  
F.G. Lightfoot ◽  
L.E. Grau ◽  
M.M. Cassidy ◽  
G.R. Tadvalkar ◽  
G.V. Vahouny
Keyword(s):  
Electron Microscopy ◽  
Morphological Changes ◽  
Large Population ◽  
Rat Colon ◽  
Gastrointestinal Disorders ◽  
Luminal Surface ◽  
Fecal Material ◽  
Transmission Electron ◽  
Morphologic Analysis ◽  
Irritable Bowel

Psyllium hydrophillic mucilloid is a natural gelling fiber consumed by a large population of our society. It is used as a bulk-producing laxative and in the treatment of gastrointestinal disorders such as “Irritable Bowel Syndrome”. The literature pertaining to the ultrastructural effects of this agent is sparse.This study documents morphological changes induced by psyllium. Animals fed a diet containing 2% psyllium for four weeks were subsequently sacrificed and processed for scanning and transmission electron microscopy. The colon contained fecal material combined with psyllium which conformed to the contour of the luminal surface. This mixture formed surface replicas of the intestinal mucosa. These replicas and their related colonic sites were processed for morphologic analysis.

Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro

1975 ◽  
Vol 33 ◽  
pp. 600-601
Author(s):  
John C. Garancis ◽  
Robert O. Hussa ◽  
Michael T. Story ◽  
Donald Yorde ◽  
Roland A. Pattillo
Keyword(s):  
Electron Microscopy ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Culture Fluid ◽  
Cellular Functions ◽  
Human Trophoblast ◽  
Transmission Electron ◽  
Marked Activity ◽  
Malignant Trophoblast

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.

The plainfin midshipman’s soundscape at two sites around Vancouver Island, British Columbia

2018 ◽  
Vol 603 ◽  
pp. 189-200 ◽  
Author(s):  
WD Halliday ◽  
MK Pine ◽  
APH Bose ◽  
S Balshine ◽  
F Juanes
Keyword(s):  
British Columbia ◽  
Vancouver Island

Liver Toxicity in Rats Fed A Mixture of Pcb Congeners and 2,3,7,8-Tcdd

1997 ◽  
Vol 3 (S2) ◽  
pp. 51-52
Author(s):  
B.J. Cornell ◽  
A. Singh ◽  
I. Chu
Keyword(s):  
Aromatic Compounds ◽  
Liver Toxicity ◽  
Corn Oil ◽  
Morphological Changes ◽  
Test Substance ◽  
Sprague Dawley ◽  
Morphological Alterations ◽  
Pcb Congeners ◽  
Transmission Electron ◽  
Sprague Dawley Rats

Polyhalogenated aromatic compounds such as polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins (PCDDs) continue to be environmental contaminants because of their bioaccumulation in the food chain and high resistance to biodegradation. The current study was undertaken to determine if a mixture of PCB congeners (WHO-IPCS) were interactive with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in producing morphological changes in the rat liver. Both compounds are known to produce a broad range of biochemical and morphological alterations including enzyme induction.Groups (N=5) of female Sprague-Dawley rats were administered TCDD (0, 2.5, 25, 250, 1000 ng/kg bw/day) or PCB (0, 2, 20 μg/kg bw/day) alone, or in combination with each concentration of both compounds. Incorrect concentrations were published in a previous abstract. The test substance was mixed with corn oil and given by gavage at 2 ml/kg daily for 28 days. At the end of the experiment, the rats were killed and liver samples were prepared for transmission electron microscopy.

scholarly journals Zinc Oxide and Silver Nanoparticle Effects on Intestinal Bacteria

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2489
Author(s):  
Ami Yoo ◽  
Mengshi Lin ◽  
Azlin Mustapha
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Morphological Changes ◽  
Intestinal Bacteria ◽  
Bacterial Cells ◽  
Ag Nps ◽  
Zno Nps ◽  
Bifidobacterium Animalis ◽  
Transmission Electron

The application of nanoparticles (NPs) for food safety is increasingly being explored. Zinc oxide (ZnO) and silver (Ag) NPs are inorganic chemicals with antimicrobial and bioactive characteristics and have been widely used in the food industry. However, not much is known about the behavior of these NPs upon ingestion and whether they inhibit natural gut microflora. The objective of this study was to investigate the effects of ZnO and Ag NPs on the intestinal bacteria, namely Escherichia coli, Lactobacillus acidophilus, and Bifidobacterium animalis. Cells were inoculated into tryptic soy broth or Lactobacilli MRS broth containing 1% of NP-free solution, 0, 12, 16, 20 mM of ZnO NPs or 0, 1.8, 2.7, 4.6 mM Ag NPs, and incubated at 37 °C for 24 h. The presence and characterization of the NPs on bacterial cells were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Membrane leakage and cell viability were assessed using a UV-visible spectrophotometer and confocal electron microscope, respectively. Numbers of treated cells were within 1 log CFU/mL less than those of the controls for up to 12 h of incubation. Cellular morphological changes were observed, but many cells remained in normal shapes. Only a small amount of internal cellular contents was leaked due to the NP treatments, and more live than dead cells were observed after exposure to the NPs. Based on these results, we conclude that ZnO and Ag NPs have mild inhibitory effects on intestinal bacteria.

scholarly journals Human serum activates the tegument of female schistosomes and supports recovery from Praziquantel

2020 ◽  
Author(s):  
Franziska Winkelmann ◽  
Marcus Frank ◽  
Anne Rabes ◽  
Nicole Koslowski ◽  
Cindy Schulz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Human Serum ◽  
Immune Reaction ◽  
Morphological Changes ◽  
Expression Profiles ◽  
Female Worm ◽  
Male Worm ◽  
Transmission Electron ◽  
Gene Expression Analyses ◽  
Males And Females

AbstractSchistosomiasis is one of the most devastating parasitic disease in the world. Schistosoma spp. survive for decades within the vasculature of their human hosts. They have evolved a vast array of mechanisms to avoid the immune reaction of the host. Due to their sexual dimorphism, with the female worm lying within the gynecophoric canal of the male worm, it is the male that is exposed to the immediate environment and the soluble parts of the host’s immune response. To understand how the worms are so successful in fending off the immune attacks of the host, comparative analyses of both worm sexes in human serum (with or without Praziquantel) were performed using scanning electron microscopy, transmission electron microscopy, and immunohistochemistry. Further, gene expression analyses of tegument-specific genes were performed. Following the incubation in human serum, males and females out of pairs show morphological changes such as an altered structure of the pits below the surface and an increased number of pits per area. In addition, female schistosomes presented a marked tuft-like repulsion of their opsonized surface. The observed resistance of females to Praziquantel seemed to depend on active proteins in the human serum. Moreover, different expression profiles of tegument-specific genes indicate different functions of female_single and male_single teguments in response to human serum. Our results indicate that female schistosomes developed different evasion strategies toward the host’s immune system in comparison to males that might lead to more robustness and has to be taken into account for the development of new anti-schistosomal drugs.

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