Immunologic effects of whole-body ultraviolet (uv) irradiation. III Defective splenic adherent cell function in alloantigen-stimulated T-cell proliferation

The daily exposure of a mouse to ultraviolet (uv) radiation causes a selective depletion of Ia-bearing adherent cells in that animal's spleen. This depletion manifests itself in functional deficiencies in the presentation of protein antigens and haptens to T cells. The present studies demonstrate a defect in splenic adherent cells (SAC) from uv-irradiated mice resulting in defective alloantigen presentation. We show that unfractionated splenocytes and SAC from uv-irradiated mice show decreased stimulatory activity in allogeneic MLR. We then utilize this phenomenon induced by uv radiation to characterize the stimulator cell in the M locus (Mls) determinant-driven MLR. We show that the stimulator cell in Mls determinant-driven MLR is an adherent cell and demonstrate that this stimulator cell bears Ia determinants by showing that whole spleen cells and SAC from mice treated with uv radiation are inefficient stimulators of the Mls determinant-driven MLR. The importance of the Ia determinant on the stimulator cells in Mls determinant-driven MLR is corroborated by the demonstration that a monoclonal antibody directed at this determinant fully blocks the Mls determinant-driven MLR. The significance of these studies to the problem of alloreactions in vivo is discussed.     

PKC-Dependent Long-Term Effect of PMA on Protein Cell Surface Expression in Caco-2 Cells

Several recent data indicate that protein traffic is under the control of different phosphorylation pathways. In previous works, we have shown that cell surface expression of apical hydrolases and of a basolateral protein, “525” antigen, was impaired in Caco-2 cells treated with forskolin, a potent PKA activator (L. Baricaultet al.,1995,J. Cell Sci.,108, 2109–2121). Surprisingly, in these experiments forskolin did not seem to act through PKA activation. These cAMP-independent effects of FK may rely on cross-talk between intracellular phosphorylation pathways as described recently for PKA and PKC pathways. Therefore, we tested the hypothesis that PKC activation may induce effects comparable to those of FK on three brush border hydrolases as well as on 525 antigen cell surface expression in Caco-2 cells. Using enzymatic activity measurements and pulse–chase experiments combined with cell surface biotinylation assays, we show that long-term treatment with phorbol 12-myristate 13-acetate (PMA) impairs the overall expression of neither brush border hydrolases nor that of the 525 antigen but decreases total cell surface expression of these proteins. The apical and basolateral delivery pathways are equally affected. Using confocal laser scanning microscopy we show that the DPP IV and the 525 antigen that were not recovered from the cell surface were sequestrated in Lamp-1-positive lysosomal-related vesicles. PMA stimulates PKC translocation even after a 3-week treatment and induces PKC? redistribution to a vesicular- and membrane-associated compartment also labeled with cytokeratins. These results demonstrate that PMA-dependent PKC activation strongly impairs protein cell surface targeting. They also suggest that these PKC-dependent effects which are similar to those previously obtained with FK are relevant to the described cross-talk between PKA- and PKC-dependent phosphorylation pathways.     

A local regulatory T cell feedback circuit maintains immune homeostasis by pruning self-activated T cells

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Changes in electrical impedance of the vaginal medium during the menstrual cycle of female rhesus monkeys (Macaca mulatta)

Changes in electrical impedance of the vaginal medium during the menstrual cycle were recorded in female Rhesus monkeys using electrical probe and were correlated with estradiol-17 beta and progesterone plasma concentrations. A gradual decrease in impedance was observed during the follicular phase, the lowest values being observed between days 12-17 of the cycle. Impedance increased again during the first third of the luteal phase until day 21. The reversal of the impedance gradient's sign was nearly concomitant with the appearance of a detectable plasma progesterone concentration. These results support the use of vaginal impedance measurements as a help for the diagnosis of the periovulatory time in the female Rhesus monkey.     

Nondisjunction induced by ethanol in Drosophila melanogaster females.

The effect of ethanol on chromosomal segregation was investigated in Drosophila melanogaster females homozygous for a structurally normal X chromosome marked with the recessive mutation yellow (y/y). For chronic treatments the females were kept from eclosion in food supplemented with 10% or 15% (v/v) ethanol, mated 24 or 48 h later to wild-type males and brooded in freshly prepared ethanol food. For the acute treatments 24- or 48-h-old females were exposed for 60 min to a 75% (v/v) ethanol solution by means of soaked tissue paper placed at the bottom of regular culture vials and brooded daily after mating. The results obtained show that: (1) both treatments significantly increased the frequency of X-chromosome nondisjunction; (2) after acute treatment this effect declined in later broods; (3) the yield of malformed flies in the progeny of acutely treated females was significantly higher than control values and also declined in later broods; (4) ovary analysis showed that chronic ethanol treatments caused a cessation of egg production. The induction pattern of nondisjunction and malformed flies is interpreted as giving support to the assumption that these effects may result from a direct action of ethanol. Ethanol toxicity was assessed by exposing females of different ages to a 50% or a 75% (v/v) solution for 60 min and counting the surviving flies 24 h later. The surviving fraction decreased steeply from 1-day-old (100%) to 5-day-old females (1.8%). It is suggested that toxicity may have been due to the action of a metabolite of ethanol, probably acetaldehyde.     

Expansion of penduline tit (Remiz pendulinus) through migration and wintering

Summary The migration and wintering ofRemiz pendulinus in western Europe is updated by analyzing the recoveries available in EURING Data Bank until 1990. The settlement of new winter quarters, the origin of the populations wintering in the Iberian peninsula and the westward shift in the winter and breeding areas, the latter spreading one season slower than the former, are assessed. A process of expansion is suggested based on the association between migration, wintering and the expansion of the breeding areas; this is supported by the parallelism between the advance and creation of new winter quarters and the advance of breeding areas: as juveniles apparently lead the winter expansion wintering farther than the former generation and as the species keeps returning to previous winter quarters, there is a continuous process of wintering expansion. The colonization of new breeding areas (mostly by juveniles) during the spring migration completes the interrelated process. The wintering, a key factor in the process, becomes, then, a hint of future expansion.

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Zusammenfassung Zug und Überwinterung der Beutelmeise in Westeuropa werden nach den Ringfunden der EURING Databank bis 1990 beschrieben. Im einzelnen lassen sich dadurch belegen: Besiedlung neuer Winterquartiere, die Herkunft der auf der Iberischen Halbinsel überwinternden Population und die Westausbreitung der Winterquartiere und Brutareale, letztere mit jeweils einem Jahr Verzögerung. Der Expansionsverlauf wird als Zusammenhang zwischen Zugverhalten, Überwinterung und der Ausdehnung des Brutareals interpretiert. Dies wird durch den parallelen Verlauf zwischen dem Vorrücken und der Wahl neuer Winterquartiere sowie der Ausweitung des Brutareals bestätigt: Jungvögel scheinen weiter zu wandern als die Vögel der vorhergehenden Generation. Da Winterquartiere im Folgejahr wieder aufgesucht werden, entsteht ein kontinuierlicher Prozeß der Ausweitung des Winterareals. Die Kolonisation neuer Brutgebiete (meist durch Einjährige) auf dem Rückzug im Frühjahr vervollständigt den in mehreren Phasen ablaufenden Prozeß. Das Überwinterungsgebiet als Schlüsselfaktor im Ausbreitungsvorgang liefert somit Hinweise auf weitere Arealausdehnung.

     

Raffinose increases sporulation and enterotoxin production by Clostridium perfringens type A.

Replacement of starch with raffinose in Duncan and Strong sporulation medium improved percent sporulation in six of eight strains tested. Enterotoxin concentration in cell extracts was increased in the case of four of five known enterotoxin-positive strains. With strain NCTC 10240, levels of 0.3, 0.4, and 0.5% raffinose produced the highest enterotoxin concentration 300 to 320 micrograms of enterotoxin per mg of cell extract protein. At a level of 0.4% raffinose the highest enterotoxin concentration in cell extracts of NCTC 10240 occurred after 8 h of growth in Duncan and Strong medium. Enterotoxin produced in the presence of starch or raffinose by three separate strains all migrated at similar Rm by polyacrylamide gel electrophoresis.     

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity

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Structure-activity relationship of a series of non peptidic RGD integrin antagonists targeting α5β1: part 1

Potent antagonists of the integrin α(5)β(1), which are RGD mimetics built from tyrosine are described. This letter describes the optimization of in vitro potency obtained by variation of two parts of the molecule, the basic group and the linker between the basic group and the phenyl central core.