Bone marrow derived macrophages have polyamine and ectoenzyme phenotypes distinct from resident macrophages

Several prototype macrophage (MO) populations were compared for differences in ectoenzyme phenotype and polyamine content. Resident peritoneal MO and Corynebacterium parvum (CP)-activated peritoneal MO expressed unique ectoenzyme phenotypes, while bone marrow derived MO (BMDMO), obtained from stem cells after 7 days in culture with colony stimulating factor, and thioglycollate (TG)-elicited peritoneal MO exhibited a similar ectoenzyme phenotype. All of the MO populations, however, differed in polyamine accumulation patterns. These results suggest that ectoenzyme phenotypes do not serve as completely selective markers of MO differentiation. Moreover, BMDMO do not resemble steady state tissue peritoneal MO but appear to resemble inflammatory MO in several respects. Therefore activated BMDMO do not appear to provide an accurate model system for their continued use in studies to characterize the development of resident tissue MO.     

Inhibitor-induced enzyme activation in organic solvents

The enzymatic activity of the protease subtilisin in anhydrous organic solvents can be dramatically increased by pretreating the enzyme before it is placed in the nonaqueous medium. For instance, lyophilization of subtilisin from aqueous solution containing competitive inhibitors (followed by their removal) created an enzyme which was up to 100 times more active than the enzyme lyophilized in the absence of such ligands. This phenomenon of ligand-induced "enzyme memory" also extends to the stability, affinity, and substrate specificity of subtilisin in organic solvents.     

Effects of corticotropin releasing hormone on appetitive behaviors.

Corticotropin releasing hormone (CRH) is a 41-residue hypothalamic neuropeptide that has been shown to have potent behavioral effects in animals and has been implicated in clinical disorders in man. This review focuses on those aspects of the behavioral effects of CRH related to food-associated behaviors. The effects of CRH on food intake are compared with its effects on performances maintained by food presentation, and contrasted with the effects of CRH on performances maintained by other events. The effects of CRH antagonists and drugs that interact with the behavioral effects of CRH are also reviewed, particularly with respect to their direct effects on food intake. Lastly, data assessing the effects of CRH administration on central neurotransmitter levels are presented and compared with levels seen in clinical populations. The effect of CRH on food intake seen in animals is consistent with a putative role for CRH in clinical syndromes where appetite suppression is apparent. Since some of the effects of CRH on food intake are subject to pharmacological intervention, strategies directed at peptidergic mechanisms of psychiatric disorders should be explored.     

Developmentally regulated antigen associated with calcium crystals in tobacco anthers

We have found and characterized an antigen associated with crystal-containing cells in the stomium and connective tissue of the anthers of Nicotiana tabacum L. (tobacco). The antigen, defined by the monoclonal antibody NtF-8B1, localizes to subcellular regions surrounding the crystals. At the light-microscope level, the antigen is detectable just after the first appearance of crystals in the connective tissue of the anther, and at approximately the same time as the appearance of crystals in the stomium. The antigen is not detectable on a Western blot, and gave inconclusive results on a test of periodate sensitivity. It is not the crystals themselves, nor is the presence of the crystals required for antibody recognition. The antigen is sensitive to heat and protease treatment, indicating that it is a protein. The antigen is not tightly membrane-bound, in spite of its localization closely surrounding the crystals. Chemical tests indicate that the druse crystals in the stomium are calcium oxalate.Abbreviations ELISA enzyme-linked immunosorbent assay - FITC fluorescein isothiocyanate This research was supported by a National Science Foundation postdoctoral fellowship to B.L.H., by National Science Foundation grants DMB-87-15799 and to W.E.F. BSR-88-18035, and by U.S. Department of Agriculture grant GAM-89-01056. The authors thank Phillip T. Evans (Louisiana State University, Baton Rouge, USA), Wilma L. Lingle, Harry T. Horner, Jr. (Iowa State University), and A. Jack Fowler, Jr., for advice and helpful discussions.     

Further observations of stage-specific effects seen after short-term hypophysectomy in the rat.

Although hypophysectomy has been a popular tool to study the effects of hormone deprivation as well as concomitant or subsequent hormone supplementation, there is relatively little morphological information available on the structural manifestation of pituitary removal on the testis. In the report, changes, in addition to those previously reported after short-term (6 days) hypophysectomy in the rat (Russell and Clermont, 1977), are described. Membrane-bound vacuoles (primarily) appeared within the basal region of the Sertoli cell at approximately the level of Sertoli-Sertoli junctions. In stages VIII through XI elongating spermatids were abnormal and manifested manchette indentation of the nucleus, a variety of other abnormal head shapes, acrosomal breaks and enlargement of the subacrosomal space. These defects were interpreted as the effect of declining hormonal levels in stage VII on spermatids that had survived the stage VII hormone sensitivity known to occur with severe hormone depletion. Abnormalities in the flagellum involving the mitochondrial sheath and fibrous sheath were detected. Preleptotene spermatocytes degenerated and could be identified in the process of doing so near the base of the seminiferous epithelium. The contact of preleptotene spermatocytes with the basal lamina was also significantly reduced. The results show that both Sertoli cell and germ cell abnormalities were present although germ cell abnormalities could be a secondary consequence of lack of appropriate stimulation of the Sertoli cell. Degeneration of basal compartment germ cells shows that germ cells other than those located in the adluminal compartment are vulnerable to hormonal withdrawal. The question of how hormone effects are mediated in the testis at midcycle to produce these effects is discussed.     

Nonlinear mechanical responses of mouse cochlear hair bundles.

The stiffness of sensory hair bundles of both inner (IHC) and outer (OHC) hair cells was measured with calibrated silica fibres in mouse cochlear cultures to test the hypothesis that the mechanical properties of the hair bundle reflect processes underlying mechanotransduction. For OHCs, the displacement of the hair bundle relaxed with time constants of 6 ms for displacements which open transducer channels and 4 ms for displacements which close the channels. The corresponding values of the time constants for IHCs were 10 ms and 8 ms, respectively. A displacement-dependent change in the stiffness of the hair bundle was not observed when the bundle was displaced orthogonally to the direction of excitation. The stiffness of the hair bundle as a function of nanometre displacements from the resting position was remarkably nonlinear. The stiffness declined to a minimum from the resting stiffness by about 12% for OHCs and 20% for IHCs when the hair bundle was displaced by about 20 nm in the excitatory direction, and it increased by a similar amount when the bundle was displaced by 20 nm in the inhibitory direction. The displacement at which the stiffness reached a minimum was within the most sensitive region of the hair-cell transducer function (receptor potential as a function of hair-bundle displacement), and the displacement at which the stiffness reached a maximum was at the point of saturation of the transducer function in the inhibitory direction. The nonlinear displacement-dependent compliance change is reversibly abolished, and the time constant of relaxation of the bundle for excitatory displacements is reversibly reduced, when mechanotransduction is blocked by the addition of either neomycin sulphate or cobalt chloride to the solution bathing the hair cells. The displacement-dependent compliance change was not apparently reduced when the receptor potential was attenuated through the substitution of sodium in the bathing solution with a less permeant cation, tetraethylammonium. These findings suggest that the nonlinear mechanical properties of the hair bundle are associated with aspects of the hair-cell mechanotransducer process. The mechanical properties of the hair bundle are discussed in relation to the 'gating-spring' hypothesis of hair-cell transduction.     

Reconstruction of a type-B configuration monkey Sertoli cell: size, shape, and configurational and specialized cell-to-cell relationships

A model of a stage-V monkey Sertoli cell was reconstructed from electron micrographs taken of semiserial sections. The configuration (type-B) was one in which spermatids were positioned near the lumen, their heads occupying shallow cylindrical recesses at the apical portion of the Sertoli cell. The cell volume was calculated to be 4,100 micron3, the surface area 2,400.68 micron2, and the surface-to-volume ratio 0.58:1. The reconstructed cell extended from the basal lamina to the tubular lumen and was generally of the tall columnar type although its surface contour was highly irregular. The dimensions of the cell [centripetal (68.46 micron), circumferential (18.40 micron), and longitudinal (21.63 micron)] were determined and cell surfaces designated. Relative and absolute surface areas of the reconstructed cell which faced other Sertoli cells, germ cells, basal lamina, and tubular lumen were calculated. Junctions and surface specializations were enumerated, catalogued, and depicted on diagrams of the cell surface. Where appropriate, type-A rat and type-B monkey Sertoli cells were compared and discussed. Morphometry was utilized to analyze the relative surface areas of germ cells adjoining the reconstructed cell to determine the percentage of their surface facing cellular and acellular elements, and these data were compared to data obtained for the rat.     

The involvement of the major surface glycoprotein (gp63) of Leishmania promastigotes in attachment to macrophages

The interaction between the macrophage and the parasite plays a central role in the continued success of Leishmania infection. The promastigote surface ligand, and its complementary macrophage membrane receptor, involved in attachment and phagocytosis are likely to exert considerable influence over the outcome of a new infection. In this study, we report experiments pertaining to one such parasite membrane protein. Initial examination of promastigote surface proteins by radiolabeling and two-dimensional-polyacrylamide gel electrophoresis revealed an abundant polypeptide with an apparent m.w. of 63,000. Lectin-binding studies indicated that it was a glycoprotein containing mannose, N-acetyl glucosamine, and N-acetyl galactosamine residues. Monospecific antiserum raised against this glycoprotein, gp63, decorated the entire promastigote plasmalemma. Univalent antibody fragments from this antiserum blocked the interaction between promastigotes and macrophages by inhibiting attachment. Anti-gp63-inhibition reduced parasite/macrophage binding to 30 to 35% of the control binding level. Additional evidence of the involvement of gp63 in attachment to macrophages was provided by studies that made use of gp63-containing proteoliposomes. These vesicles were avidly phagocytosed by macrophages. Uptake of the gp63-containing liposomes was suppressed by greater than 90% by both anti-gp63 F(ab) fragments and the oligosaccharide mannan, indicating that their phagocytosis was receptor dependent. These results demonstrate that the abundant glycoprotein gp63 plays an important role in attachment of promastigotes to macrophages, and attachment via this parasite ligand is sufficient to trigger phagocytosis.