In vitro activation and behavior of the ameboid sperm of Ascaris suum (Nematoda)

Summary A system is described for the study of activation and motility of Ascaris spermatozoa in vitro. Activation was accomplished by addition of the sperm-activating substances (SAS), extracted from the male accessory gland, to cells incubated in phosphate-buffered saline (pH 7.4) at 37–39° C under anaerobic conditions (95% N₂, 5% CO₂). Activation is characterized by a change from spherical to ameboid shape with coalescence of the refringent granules. The normal ameboid spermatozoa bear several stubby and needle-like filopodia at the lamellipodial margin. Within the lamellipodium are bundles of microfilament-like structures extending toward the pseudopodial membrane and concentrating within the needle-like filopodia. These filopodia exhibit a pendulous, sweeping motion with subsequent retraction and disappearence within the main lamellipodium. Membranes of the ameboid cells interact at the pseudopodial regions with partial fusion, as suggested by apparent membrane breakdown between interdigitating portions of the pseudopodia. Activation is complete in 5–15 min, is totally inhibited at 4° C and/or by an atmospheric environment, but can be reinitiated by transfer to anaerobic conditions at 22–9° C. Activation also requires favorable pH (6.8–8.7) and continual exposure to sufficiently high sodium concentrations (134–154mM), i.e., lowering of sodium concentration to 10 mM causes irreversible inactivation. Sodium may be replaced by potassium or lithium but not by Tris or sucrose. Proteinases (10 g/ml) can act as activators even though SAS lack detectable proteolytic activity against azoalbumin, azocasein, TAME and BTEE and SAS activation was not inhibited by TLCK or soybean trypsin inhibitor.Adult Ascaris suum were provided through the generosity of Wilson and Company, Cedar Rapids, Iowa, U.SA. This study was supported by grant number 5T01 HD00152 and postdoctoral fellowship 1F 32AI05646 from the National Institute of Health, U.S.A.     

The distribution of Ia antigens on the surfaces of lymphocytes.

The distribution of Ia antigens was studied on murine spleen lymphocytes by an ultrastructural technique employing deep freeze-etched replicas. Ia antigens were labeled on cells from appropriate congenic and recombinant strains of mice by incubating the cells with FITC-conjugated anti-Iak antibody, followed by ferritin-coupled Fab anti-FITC. Ia antigens were detected predominantly on immunoglobulin (Ig)-bearing B lymphocytes. Antigens coded for by the entire Ik region were present on the surfaces of 95% of the positive cells (from B10.BR mice) in densely packed microclusters. Ia specificities coded for by the I-A and I-C subregions (on 4R and B10.HTT mice) exhibited a more variable pattern, with 30 to 35% of the labeled cells having sparsely distributed Ia antigens in relatively discrete microclusters. Binding of anti-Iak antibody at 37 degrees C led to patch formation but not to capping. Modulation of surface Ig left Ia antigens diffusely distributed on the cell surface, indicating that these two membrane proteins are independent molecules.     

Cytoplasmic tail deletion converts membrane immunoglobulin to a phosphatidylinositol-linked form lacking signaling and efficient antigen internalization functions

Membrane-bound immunoglobulin (mIg) is the antigen receptor on B lymphocytes mediating early events in antigen presentation and signal transduction. Wild-type human mIgM constructs transfected into the murine B-cell lymphoma A20 are expressed as transmembrane proteins with antigen presentation and signaling functions comparable to the endogenous mIgG2A; the transfected wild-type mIgM is internalized rapidly after anti-Ig cross-linking. Transfected constructs lacking the normal three-amino acid cytoplasmic tail are expressed exclusively as phosphatidylinositol-linked proteins, lack both antigen presentation and signal transduction functions, and are internalized slowly following anti-Ig binding. The molecular mass of the cytoplasmic tail-deleted phosphatidylinositol-linked Ig molecule is consistent with cleavage of the transmembrane residues during processing. Cytoplasmic domains may therefore regulate the mode of expression of membrane proteins and thereby influence their functional capabilities.     

Expression of Enterocin-P in HEK Platform: Evaluation of Its Cytotoxic Effects on Cancer Cell Lines and Its Potency to Interact with Cell-Surface Glycosaminoglycan by Molecular Modeling

International Journal of Peptide Research and Therapeutics - Cancer remains one of the leading causes of death worldwide. Introduction of natural compounds with anticancer properties can be an...     

Separation and Purification of Antioxidant Peptides from Enzymatically Prepared Scorpion (Buthus martensii Karsch) Protein Hydrolysates

International Journal of Peptide Research and Therapeutics - The purpose of this study was to separate and purify antioxidant peptides from the scorpion (Buthus martensii Karsch) protein...     

Overview of Strain Characterization in Relation to Serological and Molecular Detection of Citrus tristeza <i>Closterovirus</i>

Tristeza is a devastating viral disease in all the citrus growing countries throughout the world and has killed millions of citrus trees in severely affected orchards. The citrus species grafted on sour orange rootstock are affected by this disease. Predominantly, the sweet orange, grapefruit and lime trees grafted on sour orange exhibit severe symptoms like quick decline, vein clearing, pin holing, bark scaling and degeneration leading to variable symptoms. Symptomatic expression of Citrus tristeza virus (CTV) in different hosts has been attributed to virus isolates which are from severe to mild. Different serological and molecular assays have been deployed to differentiate the strains of CTV. Citrus tristeza virus is diversified towards its strains on the basis of biological, serological and molecular characterization. Phenotypic expression is due to genetic alteration and different molecular basis have now been adopted for strain differentiation. This review will give a brief idea about the different CTV isolates, their characterization based on nucleic acid and serological assays. Different methods along with salient features for strain characterization has also been reviewed. This review will also open the new aspects towards formulation of management strategies through different detection techniques.     

First DNA Barcoding-based Inventory of Suez Gulf Fishes in Egypt and its Implication for Species Diversity

Journal of Ichthyology - The Suez Gulf is one of the most important water bodies north of the Red Sea that contribute significantly in fish production in Egypt. The current study represents the...     

MicroRNA-424-5p enhances chemosensitivity of breast cancer cells to Taxol and regulates cell cycle,apoptosis, and proliferation

Molecular Biology Reports - Combination therapy has been considered as a potential method to overcome the BC chemoresistance. MicroRNAs (miRs) have been suggested as a therapeutic factor in the...