PubMed · 4712822
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R Marks, G C Wells. 1973. Lichen simplex: morphodynamic correlates.. https://doi.org/10.1111/j.1365-2133.1973.tb07543.x
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Mating-type (MT) switching in homothallic (h90) strains of Schizosaccharomyces pombe is initiated by a DNA double-strand break (DSB) at the distal end of the expression cassette mat1. The cis-acting smt-s1 mutation C13-P11 reduces the frequency of MT switching. It is a small deletion mapping approximately 50 bp distal to the site of the DSB. From the h90 smt-s1 strain we isolated 13 mutants with a hyperspeckled iodine reaction. In these mutants the frequency of MT switching is increased. The mutations define nine different hsp genes, none of which maps in or close to the MT region. We tested one mutant of each gene for the presence of DSBs at mat1. Curiously, in none of the h90 smt-s1 hsp strains could DSBs be detected, although some sporulate nearly as efficiently as the h90 smt-n wild type. The hsp mutations show no effect in smt-0 strains; the smt-0 deletion abolishes MT switching completely. Furthermore, we tested the interaction of hsp1-1 with swi1, swi2 and swi7 mutations. hsp1-1 has no effect in swi2 strains, whereas it increases MT switching in swi7 and, to a lesser degree, in swi1 mutants.
We reported earlier the presence of a 40 kDa plasma membrane fatty acid-binding protein (FABPpm) in human placenta. This protein is thought to be involved in the sequestration of unesterified free fatty acids bound to albumin from the maternal plasma for delivery to the fetus. However, its location in human placental syncytiotrophoblasts is not known. These cells are bipolar; one side facing maternal circulation (microvillous membranes), and the other side facing fetal circulation (basal membranes). Therefore, it is important to resolve the location of this protein in trophoblast membranes in order to understand fatty acid transport and metabolism in human placenta. Isolated plasma membranes vesicles were prepared respectively from the maternal facing microvillous and fetal facing surface of the human full-term placental syncytiotrophoblast. Using these membrane preparations, fatty acid binding activity, the polyacrylamide gel electrophoresis radiobinding assay for FABPpm, and Western blot analysis of FABPpm were carried out to determine the location of this protein in these membranes. Based on the above studies we conclude that the FABPpm is located exclusively in the microvillous membranes. Since FABPpm may be responsible for FFA uptake, its location in the microvillous membranes favours the unidirectional flow of maternal FFA to the fetus.
High affinity [3H]bradykinin binding sites have been identified in human skin cryosections by in vitro autoradiography. Equilibrium binding studies were performed with increasing concentrations of [3H]bradykinin for 120 min in the presence of protease inhibitors at 4 degrees C. In saturation experiments a single class of high affinity binding sites was identified with a dissociation constant Kd of 1.2 +/- 0.8 nM (mean +/- S.E.M., n = 3) and a maximal binding capacity Bmax of 33 +/- 8 fmol [3H]bradykinin specifically bound/mg protein (mean +/- S.E.M., n = 3). Competition experiments revealed a rank order of potency with bradykinin being most effective (bradykinin = [Lys]bradykinin > [Met- Lys]bradykinin > [Tyr]bradykinin > [des-Arg9]bradykinin), whereas [des-Arg9]bradykinin was ineffective. This indicates a B2 subtype of bradykinin receptors in normal human skin. Morphological data: autoradiography revealed that bradykinin receptors were localized in the stratum basale of the epidermis. The data are consistent with the hypothesis, that these mitotic active keratinocytes express bradykinin binding sites, that fulfil the pharmacological criteria for true receptors. Diverse stimuli, including bradykinin, play a role in the mediation of cutaneous inflammatory responses (e.g. fluid extravasation, reactive cell proliferation, hyperalgesia). Our data indicate that specific kinin receptors of the stratum basale are likely to contribute to these effects.