Cell-Cell Interactions and Distal Outgrowth in Amphibian Limbs

SYNOPSIS. A current model concerning the process of limb regenerationin vertebrates is examined. According to this model (Bryantet al, 1981), new positional values in the proximal-distal limbaxis are laid down as a result of local interactions betweencells in the limb circumference. Cells with disparate circumferentialpositional values come together at the site of future outgrowthand intercalation between them generates more distal levelsof the pattern. The results of a number of experiments on surgicallycreated symmetrical limb stumps are discussed in relation tothis model. In addition, an extension of this model to accountfor digit formation is presented, and the implications of thisformulation for limb evolution are discussed.     

An Immunohistochemical Study of Localization of the Calcium-Binding Protein Recoverin in Retina of the Newt Pleurodeles waltl

The presence and localization of the calcium-binding protein recoverin, initially found in photoreceptors of the bovine eye, were immunochemically studied in retina of the new Pleurodeles waltl. Polyclonal monospecific antibodies against recoverin were raised and the methods of immunoblotting and indirect immunofluorescence were used. A protein with an apparent molecular mass of 26 kDa was found in the retina extract, which was specifically stained by the antibodies against recoverin. Localization of recoverin was studied on the retina sections: an intense reaction was found in the inner segments and a weak reaction was found in the basal part of the outer segments of photoreceptors and in Landolt's clubs of displaced bipolars. The results we obtained suggest for the first time the presence of recoverin in the retina of a representative of the Urodeles and indicate to interspecific conservativeness of this protein and differences of its localization in the retina photoreceptors in different species. The data obtained open a possibility of using recoverin as a marker protein of photoreceptors and displaced bipolars in studies of retina regeneration in newts.     

Cryofractographic study of intercellular junctions in the populations of agar-cultivated Bordetella pertussis

The characteristic feature of replicas obtained from the freeze-fractures of B. pertussis unfixed cultures developing on casein charcoal agar for 1-7 days is the associative growth of highly polymorphic cells, ensured by the ramified system of intercellular connections (IC) formed by the derivatives of the outer layers of the cell wall. This proves that the associative location of bacterial cells, linked by numerous IC, in the preparation is not the artefact appearing in the process of their chemical fixation. In replicas obtained from the freeze-fractures of B. pertussis cultures, previously fixed with glutaraldehyde, osmic acid and uranyl acetate, oval cells with the cytoplasm having a relatively homogeneous structure and with the smoothed-out three-layer cell wall prevail. As a rule, IC are limited to the sites of direct contacts between individual cells.     

Polymorphism of the SLB serologically defined (non-MHC) alloantigenic system in pigs

Six new antigenic specificities (designated SLB-2 to SLB-7) detectable with polyclonal reagents in the complement-dependent lymphocytotoxic test were determined in the SLB alloantigenic system of pigs. The SLB specificities (including the previously described SLB-1) are controlled by 13 alleles. An analysis of a further 121 double backcross matings (with 817 offspring) confirmed that the products of SLB alleles segregated independently of the SLA haplotypes (swine MHC). In addition, in 112 families of the same mating type (with 746 progeny) the map distance of the SLB locus and the highly polymorphic L blood group locus was found to be 7.82 centimorgans in the heterogametic sex and 12.57 centimorgans in the homogametic sex.     

Metabolism of adenine nucleotides in thymocyte cytoplasm and subcellular fractions after treatment with concanavalin A, papaverine and adenosine

Studies with rat thymocytes labeled with [14C]adenine and fractionated by digitonin treatment revealed that the cytoplasm of these cells contains about 60% of the total adenine nucleotide pool with a higher ATP/ADP ratio and metabolic activity as compared with the structural components. The incorporation of [14C]adenine and [14C]adenosine into thymocyte adenine nucleotides results in predominant labeling of cytoplasmic ATP, in which the specific radioactivity of this nucleoside triphosphate is two and three times as high as in subcellular structures. Concanavalin A decreases the ATP level in thymocytes without changing its specific radioactivity. This compound does not influence the total content and amount labeled adenine nucleotides in the structural fraction. Papaverine accelerates the catabolism of ATP, mainly in thymocyte cytoplasm and, in a lesser degree, in its structural fraction. In each fraction the papaverine-induced catabolism of ATP is localized in the compartment which is more intensively labeled with [14C]adenine than the whole fractionation ATP pool. Adenosine markedly accelerates adenine nucleotide catabolism in the cytoplasmic and structural fractions of thymocytes; however, only in the first one of them this acceleration is due to ATP elevation. Papaverine and adenosine do not directly influence either the content or specific radioactivity of adenine nucleotides of the structural fraction isolated from [14C]adenine-labeled thymocytes.     

Antigenic structure of Salmonella L forms studied by an immunoferritin method

The antigenic structure of the L-forms of salmonellae (S. typhimurium and S. typhi) in comparison with that of the initial bacterial cultures and revertant cultures was studied with the use of the immunoferritin method. The L-forms of salmonellae were found to retain an insignificant amount of O-antigen, as well as to have K-antigen on the surface of the cytoplasmic membrane, but in a lesser amount than the initial strains. In the cultures reverting from the L-forms of S. typhimurium and S. typhi the quantitative and qualitative characteristics of O- and K-antigens were completely restored.     

Determination of antithrombocyte antibodies in the blood serum of patients with idiopathic thrombocytopenic purpura by an immunoenzyme method

Enzyme-linked immunosorbent assay (ELISA) was developed for determination of serum antiplatelet antibodies. Platelets obtained from healthy donors of blood group 0(1) were washed off plasma and sedimented on the bottom of microtest wells. After washing off unattached platelets and blocking of plastic with albumin platelets were incubated with sera under investigation and binding of serum antibodies was detected using antihuman immunoglobulin antibodies conjugated with peroxidase. Ten patients with idiopathic thrombocytopenic purpura (ITP). 1 patient with systemic lupus erythematosus. 1 patient with red blood cell aplasia and 9 healthy donors (negative control) were studied by ELISA. Serum antibodies which effectively bound to platelets were detected in 5 patients with ITP, in patient with lupus erythematosus and in patient with red blood cell aplasia.