Ribonucleic Acid Synthesis During the Differentiation of Sporangia in the Water Mold Achlya

The role of ribonucleic acid (RNA) synthesis in the development of sporangia in the saprolegniaceous mold Achlya was studied. Methods were developed for growing and treating large populations of mycelia so that the hyphal tips would differentiate into sporangia with considerable synchrony. Under the starvation conditions imposed for the differentiation of sporangia, net RNA, deoxyribonucleic acid (DNA), and protein synthesis ceased. However, incorporation of radioactive precursors into RNA continued at a high rate throughout the period of differentiation, showing that the enzymatic mechanism for RNA synthesis was still in an active state. Actinomycin D inhibited the differentiation of sporangia and the incorporation of labeled precursors into RNA. The level of actinomycin used did not inhibit the normal outgrowth and branching of the mycelia that occurred during differentiation. Thus, DNA-dependent RNA synthesis was required for the differentiation of sporangia. Sucrose gradient analysis of newly synthesized RNA showed that only the ribosomal and soluble fractions of RNA were labeled during vegetative growth. During the differentiation of sporangia, ribosomal and soluble RNA fractions were also labeled, and, in addition, a heterodisperse fraction of labeled RNA which was heavier than ribosomal RNA appeared; this fraction was not evident in the newly synthesized RNA from vegetative mycelia.     

Plasma 11-Hydroxycorticoid Levels after Carbenoxolone Sodium

A definite rise in plasma 11-hydroxycorticoid levels has been shown in eight patients with duodenal ulcer following the oral administration of carbenoxolone sodium. A similar rise was seen in one patient with sarcoidosis whose pituitary A.C.T.H. secretion had been acutely suppressed with dexamethasone. No such rise, however, was seen in three patients suffering from adrenal insufficiency. It is suggested that carbenoxolone acts directly on the adrenal cortex, causing an increased production of corticosteroids.     

Characterization of human mammary cell types in primary culture: Immunofluorescent and immunocytochemical indicators of cellular heterogeneity

Summary Parenchymal organoidal structures that were obtained from collagenase digestion of reduction mammoplasty specimens of apparently normal human breasts have been grown in short-term primary cultures, either on plastic or on floating gels of polymerized rat-tail collagen. Three morphologically distinct major cell types are readily observed in both systems: cuboidal cells, which occupy apical positions on collagen gels; larger, epithelioid, or basal cells on gels; and elongated cells which penetrate into the gel. In addition, a fourth cell type, that of a large, flat cell, is observed less readily by phase contrast microscopy on the surface of cultures grown on plastic. Immunofluorescent and immunocytochemical staining of cultures on plastic or histologic sections of cultures on gels have been undertaken with antisera and other histochemical reagents that stain the different parenchymal cell types in vivo. Thus antisera to epithelial membrane antigen(s), monoclonal antibodies (MABs) to the defatted mammary milk fat globule membrane, peanut lectin, and keratin MAB LE61, which preferentially stain the epithelial cells of ducts in vivo, also stain the cuboidal/apical cells in vitro. The large, flat cells are stained intensely by the first three reagents but not by the last one. Antisera to collagen IV, laminin, fibronectin, actin, keratin MAB LP34, MABs to the common acute lymphoblastic leukemia antigen, and MAB LICR-LON-23.10, which showed enhanced staining for the ductal myoepithelial cells in vivo, also stain the epithelioid/elongated cells in vitro. However, the effect of the last four reagents is reduced considerably in most elongated cells, and MAB LP34 stains the large, flat cells intensely. Heterogeneous cells of intermediate morphologies and staining patterns between the cuboidal/flat cells and large epithelioid cells have also been identified. The results suggest that the cuboidal cells and large, flat cells are related to mammary epithelial cells, whereas the large epithelioid/elongated cells have some characteristics of myoepithelial cells, and that intermediate forms may exist in culture between the two parenchymal cell types. This work was supported in part by the Ludwig Institute for Cancer Research and the Cancer and Polio Research Fund. Dr. M. J. Warburton is supported by the Cancer Research Campaign.     

Anatomical Studies of Haustorium Ontogeny and the Remarkable Mode of Penetration of the Haustorium in Nuytsiafloribunda (Labill.) R. Br.

The development and structure of secondary haustoria of Nuytsia floribunda are described and compared with other Santalalean haustoria. After establishing contact with the host root, cortical folds of the haustorium grow around the root in separate directions and fuse forming a ring around it. At an early stage of development, meristematic tissue differentiates in the interior proximal part of the haustorium. Zones of collapsed layers are present in the outer cortical region. Subsequently, in the proximal part, two vascular cores, two lysigenous cavities and extensive masses of sclerenchyma develop prior to penetration of the host root. The sclerenchymatous cells form a characteristic structure, described as the sclerenchyma prong. During penetration the intrusive part of the haustorium reaches not only the host xylem but continues growing downwards until it entirely splits the host root. Comparable to a guillotine, the sclerenchyma prong is directly involved in this remarkable process. The sclerenchyma prong finally lies in the distal part of the haustorium. Following this mechanical slicing of the host root, tube-like cells of the intrusive part actively penetrate the host xylem in an axial direction.     

Release of iron from ferritin by semiquinone, anthracycline, bipyridyl, and nitroaromatic radicals

The cytotoxicity of many xenobiotics is related to their ability to undergo redox reactions and iron dependent free radical reactions. We have measured the ability of a number of redox active compounds to release iron from the cellular iron storage protein, ferritin. Compounds were reduced to their corresponding radicals with xanthine oxidase/hypoxanthine under N₂ and the release of Fe²⁺ was monitored by complexation with ferrozine. Ferritin iron was released by a number of bipyridyl radicals including those derived from diquat and paraquat, the anthracycline radicals of adriamycin, daunorubicin and epirubicin, the semiquinones of anthraquinone-2-sulphonate, 1,5 and 2,6-dihydroxyanthraquinone, 1-hydroxyanthraquinone, purpurin, and plumbagin, and the nitroaromatic radicals of nitrofurantoin and metronidazole. In each case, iron release was more efficient than with an equivalent flux of superoxide. Introduction of air decreased the rate of iron release, presumably because the organic radicals reacted with O₂ to form superoxide. In air, iron release was inhibited by superoxide dismutase. Semiquinones of menadione, benzoquinone, duroquinone, anthraquinone 1,5 and 2,6-disulphonate, 1,4 naphthoquinone-2-sulphonate and naphthoquinone, when formed under N₂, were unable to release ferrin iron. In air, these systems gave low rates of superoxide dismutase-inhibitible iron release. Of the compounds investigated, those with a single electron reduction potential less than that of ferritin were able to release ferritin iron.     

Two different sets of cis elements regulate scute to establish two different sensory patterns

Summary We have analysed the role of the achaete-scute gene complex in the development of the pattern of campaniform sensilla on the wing blade of Drosophila. We show that the complete pattern results from the superimposition of two independent subpatterns, one of which depends on the achaete gene and the other on scute. The scute subpattern comprises several clusters of sensilla, most of which seem to require the presence of control regions located upstream of the transcribed region. This is in contrast with the pattern of scute-dependent bristles, most of which depends on control elements located downstream of the transcribed region.     

Discrete Distributions of Adenosine Receptors in Mammalian Retina

Binding sites for both the adenosine A1 receptor agonists [3H]phenylisopropyladenosine and [3H]cyclohexyladenosine and the mixed A1-A2 agonist N-[3H]ethylcarboxamidoadenosine [( 3H]NECA) were localized in rabbit and mouse retinas using autoradiographic techniques. These two classes of agonists bound to very different regions of mammalian retinas. A1 agonist binding was localized to the inner retina, particularly over the inner plexiform layer. The binding of [3H]NECA was observed primarily over the retinal pigmented epithelium and the outer and inner segments of photoreceptors. [3H]NECA labeling was not affected either by including a low concentration of unlabeled A1 agonist or by pretreating tissue with N-ethylmaleimide to inhibit ligand binding at A1 sites. While virtually all of the [3H]NECA binding was displaced by an excess of unlabeled NECA, displacement with antagonist or a large excess of cyclohexyladenosine revealed that approximately 30% of the [3H]NECA binding was at non-A1,A2 sites. The majority of the binding in the outer retina thus labeled A2 receptor sites. The unique localizations of the two classes of adenosine receptors suggest different functions in visual processing.     

Extensive changes in cytokeratin expression patterns in pathologically affected human gingiva

The stratified squamous epithelium of the oral gingiva and the hard palate is characterized by a tissue architecture and a cytoskeletal composition similar to, although not identical with, that of the epidermis and fundamentally different from that of the adjacent non-masticatory oral mucosa. Using immunocytochemistry with antibodies specific for individual cytokeratins, in situ hybridization and Northern blots of RNA with riboprobes specific for individual cytokeratin mRNAs, and gel electrophoresis of cytoskeletal proteins of microdissected biopsy tissue samples, we show changes in the pattern of expression of cytokeratins and their corresponding mRNAs in pathologically altered oral gingiva. Besides a frequently, although not consistently, observed increase in the number of cells producing cytokeratins 4 and 13 (which are normally found as abundant components in the sulcular epithelium and the alveolar mucosa but not in the oral gingiva) and a reduction in the number of cells producing cytokeratins 1, 10 and 11, the most extensive change was noted for cytokeratin 19, a frequent cytokeratin in diverse one-layered and complex epithelia. While in normal oral gingiva cytokeratin 19 is restricted to certain, sparsely scattered cells of --or near--the basal cell layer, probably neuroendocrine (Merkel) cells, in altered tissue of inflamed samples it can appear in larger regions of the basal cell layer(s) and, in apparently more advanced stages, also in a variable number of suprabasal cells. Specifically, our in situ hybridization experiments show that this altered suprabasal cytokeratin 19 expression is more extended at the mRNA than at the protein level, indicating that cytokeratin 19 mRNA synthesis may be a relatively early event during the alteration. These changes in cytokeratin expression under an external pathological influence are discussed in relation to other factors known to contribute to the expression of certain cytokeratins and with respect to changes occurring during dysplasia and malignant transformation of oral epithelia.     

Linkage analysis of the Duffy blood group marker with several chromosome 1 genes in an extended pedigree with Charcot-Marie-Tooth disease

Summary We have recently demonstrated tight linkage of the Duffy blood group marker to the -spectrin gene in an extended pedigree with Charcot-Marie-Tooth neuropathy. To determine a more precise location of the Duffy blood group locus on the chromosome 1 map we have tested several more chromosome 1 genes for linkage with this marker. We found suggestive linkage with the antithrombin III and apolipoprotein A2 genes and conclusive linkage with the gene coding for -nerve growth factor.