Imre Olah

Immunocytochemical evidence for a peroxisomal localization of manganese superoxide dismutase in leaf protoplasts from a higher plant

The controversial question of the intracellular location of manganese-containing superoxide dismutase in higher plants was examined under a new experimental approach by applying the more rigorous and specific methods of immunocytochemistry to protoplasts isolated fromPisum sativum L. leaves. Manganese superoxide dismutase (EC 1.15.1.1) was purified to homogeneity from 15 kg of leaves ofPisum sativum L. Rabbits were immunized with the mangano enzyme and the antibody specific for pea manganese superoxide dismutase was purified and found not to contain antigenic sites in common with (i) human manganese superoxide dismutase, (ii) iron superoxide dismutase from eitherEscherichia coli or higher plants, or (iii) plant or animal cuprozinc-superoxide dismutase.Pisum sativum L. manganese superoxide dismutase only appears to have antigenic determinants similar to other manganese superoxide dismutases from higher land plants. The antibody to pea Mn-superoxide dismutase was used to locate the enzyme in protoplasts isolated from young pea leaves by indirect immunofluorescence, and by electron microscopy using the unlabelled antibody peroxidase-antiperoxidase method. Results from immunofluorescence showed that chloroplasts were devoid of specific fluorescence which appeared scattered over the cytosolic spaces among chloroplasts, and demonstrate the absence of manganese superoxide dismutase inside chloroplasts. The metalloenzyme was found to be localized only in peroxisomes, whereas mitochondria, the traditionally accepted site for this enzyme in many eukaryotic organisms, did not show any specific staining. The possible subcellular roles of manganese superoxide dismutase inPisum sativum L. leaves are discussed in the light of its peroxisomal location.

Light and electron microscope structure of secretory cells in the medulla of bursal follicles of normal and cyclophosphamide treated chickens.

Abstract A specialized cell was identified in the medulla of bursal follicles referred to as a secretory cell (SC). The SC, present at all ages was concentrated in the vicinity of the corticomedullary border. Each secretory cell near the nucleus usually possessed a single long process containing 3–10 dark granules surrounded by a membrane. The SC increased in number and apparent secretory activity after cyclophosphamide treatment. All medullary pores were filled with a darkly staining substance, apparently secreted by the SC.

A continuum of cells leading to an in-vivo humoral response

A fortuitous series of observations reported in 1955-56 allowed the first demonstration that a lymphoid structure, the bursa of Fabricius, exerts a profound influence on humoral immunity. These and later studies contributed to our understanding of the role of the cell in immunology and, in particular, to the T- and B-cell concept. The bursa gained acceptance as an exporter of specialized lymphocytes following the demonstration of certain bursa-dependent cell populations in specific regions of peripheral lymphoid tissue such as thegerminal centre. Here Bruce Glick and Imre Olah discuss a newly identified family of cells which they believe may influence B-cell differentiation.

Effect of soluble antigen on the ellipsoid-associated cells of the chicken's spleen.

The ellipsoid‐associated cells (EAC) localize on the surface of the ellipsoid. They bind the IV injected horseradish peroxidase (HRP) and bovine serum albumin (BSA), migrate to the red pulp and then enter the systemic circulation. After protein injection, the number of white blood cells increased above the normal level. The highest number of white blood cells occurred between 4 and 6 hr after HRP injection. In this period, the cell enhancement resulted in HRP‐positive mononuclear cells which might come from the spleen. This cell population may vary in size and number in the blood and may be identical with the dendritic cell of the chicken. The other type of blood mononuclear cell is histologically identical with the classical monocyte endogenous peroxidase positive type and their number is lower than that of the former. This type of monocytic (MN) cell could be of bone marrow origin.

Lymphopineal tissue in the chicken

We have studied the chickens pineal gland by light and electron microscopy at 3 and 4 weeks of age. The results indicated that lymphocytes, plasma cells, secretory cells, basophil and eosinophil granulocytes enter the parenchyma and a new histologically defined tissue is formed which we call lymphopineal tissue. Inside the pineal parenchyma, the number of thymidine labeled cells is almost three times higher than in the interstitium suggesting that the pineals products might be blastogenic for the cells and/or exert an influence on post-thymic T-cell differentiation.

Effect of surgical bursectomy on the ellipsoid, ellipsoid-associated cells, and periellipsoid region of the chicken's spleen.

Surgical bursectomy resulted in cellular depletion of the periellipsoid white pulp, confirming its bursa dependency. Also, in bursectomized birds, the ellipsoid could not be identified, although a small number of abnormal ellipsoid‐associated cells (EAC) were observed in the periellipsoid region. The most characteristic finding was the degeneration of the EAC. Degeneration of EAC indicated that the intact bursa was mandatory for normal differentiation of cells of the periellipsoid white pulp into EAC. The promoting effect of the bursa might take place by a bursal hormone. The histological impairment of the EAC was followed by reduced carbon binding and migrating capabilities. Bursectomy resulted in a shift in bacterial phagocytosis in that many cells of the periellipsoid phagocytosed Salmonella. The reduced heterophil infiltration of the ellipsoid in bursectomized birds might be explained by the impaired granular content of the EAC. The impaired migration capability of the EAC might contribute to the low number of germinal centers in bursectomized birds.

Secretory cells in the medulla of the bursal follicle: the small lymphocyte-like cells are precursors of the secretory cells.

Abstract In our morphological study we have identified Sll which are structurally similar to small lymphocytes. It is suggested that the Sll belong to the null cell population of the bursa of Fabricius are blood-borne cells with proliferative capabilities and are precursors of the secretory cells. The transformation of Sll into Sc may be facilitated by Cy treatment.

An electron and light microscope study of the caecal tonsil: The basic unit of the caecal tonsil

Abstract The caecal tonsil (CT) develops in the initial 4–18 mm of each of the chickens caecal pouches. Utilizing scanning and transmission electron microscopy and light microscopy we identified the basic unit of the CT. The basic unit contains a central crypt with several primary branches, dense lymphoid tissue and germinal centers. The main structural design of the CT appears to correspond to the mammalian palatine and lingual tonsils.