229 research outputs found

    Histopathological alterations associated with Perkinsus spp. infection in the softshell clam Mya arenaria

    Get PDF
    Softshell clams (Mya arenaria) collected from the Chester River in the upper Chesapeake Bay showed the presence of Perkinsus spp, in similar to 12 % (28/240) Of clams examined. The infection seems to run a mild course with the host prevailing in encapsulating invading parasites. The gills appear to be the major site of infection, however, the parasite was also found in the digestive gland, gonads, and kidneys and occasionally in the tissue and sinuses of adductor muscles. Typically, clusters of protozoal cells were embedded in on amorphous PAS-positive substrate and were surrounded by one or more layers of granulocytes. In heavy infections, both free and encapsulated Perkinsus spp. cells were observed in affected tissue forming aggregations of different sizes. Within the tissues of M. arenaria, the parasite propagated by schizogony. The presence of large encapsulations in vital organs such as the gills and gonads may adversely affect growth and fertility of affected clams

    In vitro propagation of two Perkinsus species from the softshell clam Mya arenaria

    Get PDF
    Two continuous, axenic cultures of Perkinsus spp. (H49 and G117)were obtained from the softshell clam Mya arenaria collected from Swan Point in the Chester River, Chesapeake Bay (Maryland). Isolate H49 was obtained from the hemolymph of a heavily infected clam. Except for their larger size, H49 trophozoites and schizonts exhibited the characteristic morphology of Perkinsus marinus and divided by schizogony. Isolate G117 was obtained from a combined gill/palp sample of a moderately infected clam. Unlike H49, vegetative forms (trophozoites and schizonts) of G117 were present along with prezoosporulation stages in the same culture. In culture, G117 cells multiplied by both schizogony and successive bi-partition. Both H49 and G117 cells reacted positively with anti-Perkinsus marinus polyclonal serum and formed hypnospores upon incubation in Ray\u27s fluid thioglycolate medium that stained black with Lugol\u27s iodine. This is the first isolation of Perkinsus species from the softshell clam. Studies to determine the infectivity, pathogenicity, enzyme activities, and genotyping of both softshell clam Perkinsus spp. are ongoing

    Prevalence Of Perkinsus Spp. In Chesapeake Bay Soft-Shell Clams, Mya Arenaria Linnaeus, 1758 During 1990-1998

    Get PDF
    Prevalence and intensity of Perkinsus spp. infections were determined in soft-shell clams Mya arenaria during 1990 to 1998 based upon incubation of rectal tissues in Ray\u27s fluid thioglycollate medium. During the study, soft-shell clams were collected from 18 sites in the upper Chesapeake Bay in Maryland. Enlarged hypnospores were found in similar to 7% (114/1,705) of the soft-shell clams. Peak prevalences occurred in the fail of 1992 with similar to 53% (16/30) at Piney Point and 50% (15/30) at Eastern Neck, and in August 1995 with similar to 64%(18/28) and similar to 37% (11/30) at Cedar Point and Piney Point, respectively. This investigation provides evidence that Perkinsus spp. infections in soft-shell clams are more common than previously thought

    Revival-collapse phenomenon in the quadrature squeezing of the multiphoton intensity-dependent Jaynes-Cummings model

    Full text link
    For multiphoton intensity-dependent Jaynes-Cummings model (JCM), which is described by two-level atom interacting with a radiation field, we prove that there is a relationship between the atomic inversion and the quadrature squeezing. We give the required condition to obtain best information from this relation. Also we show that this relation is only sensitive to large values of the detuning parameter. Furthermore, we discuss briefly such relation for the off-resonance standard JCM.Comment: 14 pages, 6 figure

    Zoosporulation of a new Perkinsus species isolated from the gills of the softshell clam Mya arenaria

    Get PDF
    A gill-associated Perkinsus sp. isolated from the softshell clam (Myo arenaria) is described as a new species, P. chesapeaki sp. nov. Examination of the parasite in seawater cultures revealed life cycle stages and zoosporulation processes similar to those described for other species of the genus Perkinsus. Prezoosporangia developed thickened cell walls upon contraction of the cytoplasm and development of a distinctive clear area between the cell wall and the protoplast. Successive bipartition of the protoplast led to the formation of hundred\u27s of zoospores within mature sporangia. Zoospores were released into seawater through one or more discharge tubes, Ultrastructural studies revealed an oblong zoospore possessing two flagella that arose from a concave side located in the upper third of the zoospore body. The anterior flagellum possessed a unilateral array of hair-like structures. A large anterior vacuole and basolateral nucleus dominated the cytoplasm of the zoospore body. The presence of a rudimentary apical complex including an open-sided conoid, rhoptries, micronemes, and subpellicular microtubules were also discerned. Differences in zoospore morphology, and sequence analyses of two genes previously reported, support the designation of the gill-associated Perkinsus from the softshell clam as a new species

    The Terminal Immunoglobulin-Like Repeats of LigA and LigB of Leptospira Enhance Their Binding to Gelatin Binding Domain of Fibronectin and Host Cells

    Get PDF
    Leptospira spp. are pathogenic spirochetes that cause the zoonotic disease leptospirosis. Leptospiral immunoglobulin (Ig)-like protein B (LigB) contributes to the binding of Leptospira to extracellular matrix proteins such as fibronectin, fibrinogen, laminin, elastin, tropoelastin and collagen. A high-affinity Fn-binding region of LigB has been localized to LigBCen2, which contains the partial 11th and full 12th Ig-like repeats (LigBCen2R) and 47 amino acids of the non-repeat region (LigBCen2NR) of LigB. In this study, the gelatin binding domain of fibronectin was shown to interact with LigBCen2R (KD = 1.91±0.40 µM). Not only LigBCen2R but also other Ig-like domains of Lig proteins including LigAVar7'-8, LigAVar10, LigAVar11, LigAVar12, LigAVar13, LigBCen7'-8, and LigBCen9 bind to GBD. Interestingly, a large gain in affinity was achieved through an avidity effect, with the terminal domains, 13th (LigA) or 12th (LigB) Ig-like repeat of Lig protein (LigAVar7'-13 and LigBCen7'-12) enhancing binding affinity approximately 51 and 28 fold, respectively, compared to recombinant proteins without this terminal repeat. In addition, the inhibited effect on MDCKs cells can also be promoted by Lig proteins with terminal domains, but these two domains are not required for gelatin binding domain binding and cell adhesion. Interestingly, Lig proteins with the terminal domains could form compact structures with a round shape mediated by multidomain interaction. This is the first report about the interaction of gelatin binding domain of Fn and Lig proteins and provides an example of Lig-gelatin binding domain binding mediating bacterial-host interaction

    Novel thoracoscopic approach to posterior mediastinal goiters: report of two cases

    Get PDF
    Trans-cervical resection of posterior mediastinal goiters is usually very difficult, requiring a high thoracotomy. Until recently, using conventional video-assisted thoracoscopic surgery to resect such tumors has been technically difficult and unsafe. By virtue of 3 dimensional visualization, greater dexterity, and more accurate dissection, the Da Vinci robot, for the first time, enables a completely minimally invasive approach to the posterior superior mediastinum
    • …
    corecore