Longitudinal continuity of the subrhabdomeric cisternae in the photoreceptors of the compound eye of the drone, Apis mellifera

It is shown that the subrhabdomeric cisternae of the honey bee drone photoreceptor cell constitute a single structure with a continuous lumen, that extends over at least 15 micron and perhaps the whole length of the cell. In this case, the structure of the cisternae might subserve the propagation of light adaptation along the cell.     

Polyreactive antibodies in adaptive immune responses to viruses

B cells express immunoglobulins on their surface where they serve as antigen receptors. When secreted as antibodies, the same molecules are key elements of the humoral immune response against pathogens such as viruses. Although most antibodies are restricted to binding a specific antigen, some are polyreactive and have the ability to bind to several different ligands, usually with low affinity. Highly polyreactive antibodies are removed from the repertoire during B-cell development by physiologic tolerance mechanisms including deletion and receptor editing. However, a low level of antibody polyreactivity is tolerated and can confer additional binding properties to pathogen-specific antibodies. For example, high-affinity human antibodies to HIV are frequently polyreactive. Here we review the evidence suggesting that in the case of some pathogens like HIV, polyreactivity may confer a selective advantage to pathogen-specific antibodies.     

The immunopotentiating effect of thiosulphate in vivo

Sodium thiosulphate injected i.v. into mice causes a marked increase in concentration of several serum proteins, particularly immunoglobulins. When given together with antigen, it significantly potentiates the T-dependent humoral responses.     

Molecular recognition in antibodies and its application

The structure and function of immunoglobulins, and the nature of the antibody — antigen interaction are described. Applications of the molecular recognition properties of antibodies are discussed in the areas of immunotherapy, immunoassay, immunotargeting and catalytic antibodies.     

Mode of action of a soluble restricted factor, a suppressor of the allogeneic proliferative response in man

Appearance of "suppressor cells" is induced by in vitro hyperimmunization of lymphocytes against allogeneic cells, incompatible for one HLA-DR antigen. These "suppressor cells under certain conditions, release in the culture medium, "suppressor factors" of the in vitro allogeneic proliferative response in Man. They are not immunoglobulins and act in a non specific way towards the stimulators. Only one of them is restricted to some individuals. This is shown when either responders or stimulators are incubated for different periods, with the "suppressor factors" prior to the primary mixed lymphocyte reaction (MLRI). The beneficial effect of transfusions on kidney graft survival, could be, in part, explained by a suppressor mechanism, analogous to the one described in vitro.     

The immunopotentiating effect of thiosulphate in vivo

Summary Sodium thiosulphate injected i.v. into mice causes a marked increase in concentration of several serum proteins, particularly immunoglobulins. When given together with antigen, it significantly potentiates the T-dependent humoral responses.This work has been supported by grant No. 10.5. from the Polish Academy of Science.     

Apparent transitory hyperthyrotropinemia of mothers and newborn infants related to the presence of maternal immunoglobulins

Some newborns infants (screened for congenital hypothyro?dism) and their mothers were found to present an apparent isolated hyperthyrotropinemia. A large molecular size material (150 000 dalton) was found to carry the apparent immunoreactivity and was characterized as immunoglobulins, capable of binding TSH as well as Rabbit IgG. These maternal immunoglobulins are passively transferred to the newborn infants and interfere in various radioimmunoassays.     

Coating of centrospheres by reticulum cisternae and formation of spindle residues in segmentation mitosis under the action of an antitubulin substance: nocodazole]

When cleaving eggs are treated by nocodazole the reticulum cisternae coat the centrospheres instead of the chromosomes, as normally occurs at the late anaphase. At the same time the spindle is reduced to a common mass or spindle remnant, constituted of unorientated and fragmented microtubules which embed the kinetochores, i. e. the star configuration of the chromosomes. This action is quite similar to that of chloralhydrate but is different from that of colchicine.     

Protein localization in the plant Golgi apparatus and the <Emphasis Type="Italic">trans</Emphasis>-Golgi network

This review presents plant-specific characteristics of the Golgi apparatus and discusses their impact on retention of membrane proteins in the Golgi or the trans-Golgi network (TGN). The plant Golgi consists of distinct stacks of cisternae that actively move throughout the cytoplasm. The Golgi apparatus is a very dynamic compartment and the site for maturation of N-linked glycans. It is also a factory for complex carbohydrates that are part of the cell wall. The TGN is believed to be the site from where vacuolar proteins are sorted by receptors towards each type of vacuole. To maintain the structure and specific features of the Golgi, resident proteins ought to be maintained in the proper Golgi cisternae or in the TGN. Two families of membrane proteins will be taken as examples for Golgi/TGN retention: (i) the enzymes involved in N-glycosylation processes and (ii) a vacuolar sorting receptor. Although the number of available plant proteins localized in Golgi/TGN is low, the basis of retention appears to be shared over all kingdoms and may result from pure retention and recycling mechanisms. In this review, we will summarize the characteristics of a plant Golgi and will discuss especially their consequences on on the study of this highly dynamic structure. We then choose membrane proteins with a single transmembrane domain to illustrate the signals and mechanisms involved in plants to localize and maintain proteins in the Golgi and the TGN.     

Histochemical localization of cholinesterases in the neural tissue of the pineal in the rhesus monkey.

The neural tissue of the monkey pineal contains both acetyl and butyryl cholinesterases. Acetylcholinesterase was localized in the cisternae of the nuclear membrane, rough endoplasmic reticulum, on the plasma membrane of the neurones, and on the axolemma of both non-myelinated and myelinated fibres. The enzyme was not found in the axosomatic or axo-dendritic synapses. It is therefore suggested that the pineal neurones have a cholinergic function rather than a cholinoceptive one.     

Proopiomelanocortin expression in the skin during induced hair growth in mice.

We demonstrate for the first time a hair cycle-dependent gene and protein expression of proopiomelanocortin in mouse skin in vivo. Northern blot detected POMC mRNA with an apparent size of 0.9 kb in anagen but not telogen skin. Western blot emphasized a specific protein of 30-33 kDa recognized by anti beta-endorphin in late but not early anagen or telogen skin. By immunocytochemistry, beta-endorphin antigen was localized in the sebaceous gland in a hair cycle dependent manner.     

Are Rab proteins the link between Golgi organization and membrane trafficking?

The fundamental separation of Golgi function between subcompartments termed cisternae is conserved across all eukaryotes. Likewise, Rab proteins, small GTPases of the Ras superfamily, are putative common coordinators of Golgi organization and protein transport. However, despite sequence conservation, e.g., Rab6 and Ypt6 are conserved proteins between humans and yeast, the fundamental organization of the organelle can vary profoundly. In the yeast Saccharomyces cerevisiae, the Golgi cisternae are physically separated from one another, while in mammalian cells, the cisternae are stacked one upon the other. Moreover, in mammalian cells, many Golgi stacks are typically linked together to generate a ribbon structure. Do evolutionarily conserved Rab proteins regulate secretory membrane trafficking and diverse Golgi organization in a common manner? In mammalian cells, some Golgi-associated Rab proteins function in coordination of protein transport and maintenance of Golgi organization. These include Rab6, Rab33B, Rab1, Rab2, Rab18, and Rab43. In yeast, these include Ypt1, Ypt32, and Ypt6. Here, based on evidence from both yeast and mammalian cells, we speculate on the essential role of Rab proteins in Golgi organization and protein transport.     

Histochemical localization of cholinesterases in the neural tissue of the pineal in the rhesus monkey

Summary The neural tissue of the monkey pineal contains both acetyl and butyryl cholinesterases. Acetylcholinesterase was localized in the cisternae of the nuclear membrane, rough endoplasmic reticulum, on the plasma membrane of the neurones, and on the axolemma of both non-myelinated and myelinated fibres. The enzyme was not found in the axosomatic or axo-dendritic synapses. It is therefore suggested that the pineal neurones have a cholinergic function rather than a cholinoceptive one.This study was supported by the WHO.     

Binding bovine immunoglobulins to anterior lobe cells of the hypophysis.

Cells of the anterior lobe of the bovine hypophysis, show an affinity for immunoglobulins IgG, IgA and IgM. The phenomenon either provides a message to stimulate cellular secretion or to excite mechanisms associated with the synthesis and release of Ig's or their determinants.     

Structural alterations in rat kidney proximal tubules perfused with fresh autologous serum

Two min of intraluminal perfusion of the rat proximal tubules with autologous serum induced marked ultrastructural alterations including extensive cytoplasmic vesiculation due to swelling of rough endoplasmic reticulum cisternae and occasional extrusion of nuclei and cytoplasm into the lumen. Within 4 min pronounced vesiculation of mitochondria was observed. These findings are consistent with the notion that serum-induced inhibition of proximal tubular fluid absorption is due to cell lysis, presumably mediated by complement activation.     

Molecular chaperones in the processing and presentation of antigen to helper T cells

Helper T lymphocytes recognize peptide fragments of antigen bound to Major Histocompatibility Complex (MHC) class II molecules on the surfaces of antigen presenting cells (APC). Antigen processing involves internalization of the antigen into an acidic compartment where the antigen is degraded and the resulting peptide fragments of the antigen are bound to MHC class II molecules and the complexes subsequently displayed at the APC surface. Thus, antigen processing represents a complex, intracellular assembly process which may, like many intracellular protein folding and assembly processes, require the function of molecular chaperones. This contribution focuses on the evidence which suggests that members of the heat shock protein family of molecular chaperones play a role in this pathway.     

Binding bovine immunoglobulins to anterior lobe cells of the hypophysis

Summary Cells of the anterior lobe of the bovine hypophysis, show an affinity for immunoglobulins IgG, IgA and IgM. The phenomenon either provides a message to stimulate cellular secretion or to excite mechanisms associated with the synthesis and release of Ig's or their determinants.This study was supported by a grant from the National Research council of Canada.     

Human peripheral blood monuclear cells transfected with messenger RNA stimulate antigen-specific cytotoxic T-lymphocytes in vitro

The efficiency of test vaccines needs to be evaluated by quantification of the triggered cellular immune response. Usually, for these assays, autologous target cells expressing the vaccine antigen are required. In the context of messenger RNA (mRNA)-based vaccinations, the target cells used for the read-out are mRNA-transfected monocyte-derived dendritic cells (Mo-DCs). Their production typically requires samples of 100 ml blood from the patients, and limits the number of assays that can be performed. We show here that fresh peripheral blood mononuclear cells (PBMCs) can be transfected with mRNA by electroporation. Such cells are as efficient as mRNA-transfected Mo-DCs for their ability to activate memory T cells in vitro. Thus, mRNA-transfected PBMCs are a convenient replacement of mRNA-transfected Mo-DCs for the in vitro monitoring of natural or vaccine-induced immune responses.Received 17 February 2005; received after revision 1 May 2005; accepted 7 Juni 2005     

The plasminogen activator system: biology and regulation

The regulation of plasminogen activation involves genes for two plasminogen activators (tissue type and urokinase type), two specific inhibitors (type 1 and type 2), and a membrane-anchored urokinase-type plasminogen-activator-specific receptor. This system plays an important role in various biological processes involving extracellular proteolysis. Recent studies have revealed that the system, through interplay with integrins and the extracellular matrix protein vitronectin, is also involved in the regulation of cell migration and proliferation in a manner independent of proteolytic activity. The genes are expressed in many different cell types and their expression is under the control of diverse extracellular signals. Gene expression reflects the levels of the corresponding mRNA, which should be the net result of synthesis and degradation. Thus, modulation of mRNA stability is an important factor in overall regulation. This review summarizes current understanding of the biology and regulation of genes involved in plasminogen activation at different levels. Received 21 December 1998; received after revision 8 March 1999; accepted 14 April 1999