Formaldehyde-induced appearance of septate junctions between digestive vacuoles

Tissue biopsies from (1) some chronic inflammatory diseases, (2) a necrotic tumoral process, (3) normal human lymphatic ganglia, and (4) two congenital diseases of the adrenal cortex were selected for study. A block from each biopsy was fixed in glutaraldehyde-paraformaldehyde; a second block was fixed in 10% formaldehyde. In all cases septate junctions between digestive vacuoles did occur in phagocytic cells and some adrenal cortex cells fixed in formaldehyde. These junctions were similar to those reported recently for malakoplakia phagocytes. Consistently, they were not found to attach organelles other than lysosomes derivatives. Both phagocytes and adrenal cortex cells in the material fixed in glutaraldehyde-paraformaldehyde did not display adhesive specializations between digestive vacuoles. This suggests that the septate junctions described herein are artifactuous structures induced by formaldehyde. There is, however, a certain degree of specificity of cells having the capability of developing these septate junctions. It is assumed that the coating material of digestive organelles in phogocytes and some other cells would be responsible for both cell specificity and organelle specificity of the formaldehyde-induced septate junctions.     

Oviposition and development of Drosophila modified by magnetic fields

Drosophila flies placed in a habitat with two lateral boxes demonstrated sensitivity to magnetic fields: Oviposition decreased by exposure to pulsated extremely low frequency (ELF) (100)Hz, 1.76 miliTesla (mT) and sinusosidal fields (50 Hz, 1 mT), while there was no initial effect of exposure to a static magnetic field (4.5 mT). Drosophila eggs treated for 48 h with the above described fields showed that (1) mortality of eggs was lower in controls than in eggs exposed to all tested magnetic fields; (2) mortality of larvae increased when a permanent magnet was used; (3) mortality of pupae was highest when a permanent magnet was used; and (4) general adult viability was highest in controls (67%) and diminished progressively when eggs were exposed to pulsated (55%), sinusoidal (45%), and static (35%) magnetic fields.     

Nigericin forms highly stable complexes with lithium and cesium

Nigericin is a monocarboxylic polyether molecule described as a mobile K⁺ ionophore unable to transport Li⁺ and Cs⁺ across natural or artificial membranes. This paper shows that the ion carrier molecule forms complexes of equivalent energy demands with Li⁺, Cs⁺, Na⁺, Rb⁺, and K⁺. This is in accordance with the similar values of the complex stability constants obtained from nigericin with the five alkali metal cations assayed. On the other hand, nigericinalkali metal cation binding isotherms show faster rates for Li⁺ and Cs⁺ than for Na⁺, K⁺, and Rb⁺, in conditions where the carboxylic proton does not dissociate. Furthermore, proton NMR spectra of nigericin-Li⁺ and nigericin-Cs⁺ complexes show wide broadenings, suggesting strong cation interaction with the ionophore; in contrast, the complexes with Na⁺, K⁺, and Rb⁺ show only clear-cut chemical shifts. These latter results support the view that nigericin forms highly stable complexes with Li⁺ and Cs⁺ and contribute to the explanation for the inability of this ionophore to transport the former cations in conditions where it catalyzes a fast transport of K⁺>Rb⁺>Na⁺.Part of the results of this paper were presented at the 14th International Congress of Biochemistry in Prague, Czechoslovakia.     

Persistence of Cell Division Synchrony in Spirogyra Insignis (Gamophyceae): Membrane Proteoglycans Transmitting Synchronizing Information Throughout Generations

Spirogyra insignis shows a long-term persistence of cell division synchrony in the absence of the synchronizing Zeitgeber, so that at least six generations are involved in the process. This tentatively suggests that a mechanism of transmission throughout generations of synchronizing information could maintain this synchrony. Apparently, a vital part of the molecular basis of this mechanism is a membrane proteoglycan complex. This complex could obtain temporal information from a synchronizing Zeitgeber and be transmitted to the progeny by distribution of plasma membrane between daughter cells.     

Primitive streak-forming cells of the chick invaginate through a basement membrane

Summary Recently fibronectin was shown to appear in the development of the chick for the first time as a thin band on the epiblastic side facing the hypoblast just prior to primitive streak formation. It was thus suggested that fibronectin might be instrumental in the migration of cells that lead to axis formation during primitive streak formation. In the present work we have examined simultaneously for the presence of fibronectin and the specific basement membrane glycoprotein laminin during primitive streak formation using immunofluorescence methods. Laminin was found to be expressed between the epiblast and the hypoblast of stage XIII¹ chick blastoderms. During the immediately following process of streak formation the laminin was found to be continuously detectable throughout the area covered by the hypoblast, but disrupted on the streak area. Fibronectin was found to co-distribute with laminin in stage XIII and in the early primitive streak chick blastoderms. It is concluded that at stage XIII laminin and fibronectin form part of a basement membrane that is partially disrupted during the immediately following process of primitive streak formation in order to allow the migration of the streak-forming epiblastic cells during this morphogenetic process.     

The taxonomy of the family Paramphistomidae Fischoeder, 1901 with special reference to the morphology of species occurring in ruminants. II. Revision of the genus Paramphistomum Fischoeder, 1901

Summary The genus Paramphistomum Fischoeder, 1901 is redefined and restricted and only the following species are retained and considered valid: P. cervi (Zeder, 1790) (type species); P. liorchis Fischoeder, 1901; P. gracile Fischoeder, 1901 P. epiclitum Fischoeder, 1904; P. gotoi Fukui, 1922, P. ichikawai Fukui, 1922; P. leydeni Näsmark, 1937 and P. hiberniae Willmott, 1950. These are redescribed and illustrated. A new species, Paramphistomum cephalophi is described and illustrated from the black-fronted duiker (Cephalophus nigrifrons) in Rwanda. It differs from the rest of the species in the genus by the presence of an anterior sphincter in the pharynx and the characteristic posterior notch of the acetabular rim. Scanning electron photomicrographs of the tegumental surfaces of the species in the genus are provided. Cotylophoron indicum Stiles & Goldberger, 1910 (=Paramphistomum thapari Price & McIntosh, 1953), C. madrasense Gupta, 1958, C. chauhani Gupta & Gupta, 1972, Paramphistomum indicum Stiles & Goldberger, 1910 (in part), P. malayi Lee & Lowe, 1971 and Srivastavaia indica Singh, 1970 are considered synonyms of Paramphistomum epiclitum Fischoeder, 1904. Paramphistomum indicum Stiles & Goldberger, 1910 (in part) and P. bombayiensis Gupta & Verma in Gupta & Nakhasi, 1977 are regarded as synonyms of Paramphistomum gracile Fischoeder, 1901. P. scotiae Willmott, 1950, P. julimarinorum Velázquez-Maldonado, 1976, P. nicabrasilorum Velázquez- Maldonado, 1976, P. procapri Wang, 1979 and Cotylophoron skrjabini Mitskevich, 1958 are considered synonyms of Paramphistomum leydeni Näsmark, 1937. Cotylophoron vigisi Davydova, 1963 is considered synonymous with Paramphistomum ichikawai Fukui, 1922. Paramphistomum birmense Railliet, 1924, P. microon Railliet, 1924, P. chinensis Hsu, 1935 and P. pseudocuonum Wang, 1979 are regarded as species inquirendae.The genera Liorchis Velichko, 1966 and Srivastavaia Singh, 1970 are synonymized with Paramphistomum Fischoeder, 1901.A key to the species of the genus is provided.Part of a thesis approved by the University of London for the award of the Ph.D. degree.Part of a thesis approved by the University of London for the award of the Ph.D. degree.     

Degradation of [α-14C]hordenine in Hordeum vulgare plants

Evidence is presented indicating that intact plants of Hordeum vulgare degrade [α- ¹⁴C]hordenine to ¹⁴CO ₂.     

Novel Tools to Analyze the Function of Salmonella Effectors Show That SvpB Ectopic Expression Induces Cell Cycle Arrest in Tumor Cells

In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ∆purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors.