Transient expression of a Ca2+-activated Cl- current during development of quail sensory neurons

The expression of a calcium-activated chloride current (ICl(Ca)) was studied during the development of the sensory neurons of quail trigeminal ganglia. This current is expressed in 20% of the neurons by the 5th day of embryonic development; it can be found in nearly all neurons by the 7th day and subsequently disappears in half of them. Similar results were obtained with dorsal root ganglion neurons. The disappearance of ICl(Ca) in part of the sensory neurons during development is not due to a selective death of the neurons possessing this current and our results suggest that it is mediated by an interaction of the sensory neurons with their target tissue.     

EPR study of the redox interactions in cytochrome c3 from Desulfovibrio vulgaris Miyazaki

We present a new examination of the EPR redox titration data for the tetraheme cytochrome c3 from Desulfovibrio vulgaris Miyazaki. Our analysis includes the contribution of the interaction potentials between the four redox sites and is based on the model previously developed for the study of cytochrome c3 from Desulfovibrio desulfuricans Norway. We observed, as for D. desulfuricans Norway cytochrome c3, that the conformation of the heme with the lowest redox potential, heme 4, is sensitive to the redox state of the heme with the highest potential, heme 1. However in D. vulgaris Miyazaki cytochrome c3 spectral simulations show that heme 4 is present in two conformational states which interconvert partially when heme 1 is reduced. The sets of redox parameters which satisfy the fitting procedure of the titration curves are in the following domain: -250 mV less than or equal to e41 less than or equal to -220 mV, -325 mV less than or equal to e2 less than or equal to -320 mV, -335 mV less than or equal to e3 less than or equal to -330 mV, -360 mV less than or equal to e4 less than or equal to -355 mV, -5 mV less than or equal to I12 less than or equal to 20 mV, -10 mV less than or equal to I13 less than or equal to 5 mV, -15 mV less than or equal to I23 less than or equal to -5 mV, -15 mV less than or equal to I24 less than or equal to -10 mV, -25 mV, less than or equal to I34 less than or equal to -15 mV. As in D. desulfuricans Norway cytochrome c3 the interactions are moderate. Simple electrostatic considerations suggest that these moderate values could be related to the large accessibility of the hemes to the solvent. Our work does not confirm the existence of a cooperative interaction between heme 2 and heme 3 which has been proposed on the basis of electrochemical measurements.     

Atrazine and diuron resistant plants from photoautotrophic protoplast-derived cultures of Nicotiana plumbaginifolia

Atrazine and diuron resistant clones were isolated from diploid photoautotrophic protoplastderived colonies of Nicotiana plumbaginifolia. Protoplasts were mutagenised with 0.1 mM N-ethyl-N-nitrosourea and colonies were screened for resistance after plating. Selection of calli was carried out on their ability to grow and green on a selective medium containing either atrazine or diuron. Plants were regenerated from most tolerant calli. Herbicide spray showed that plants of 6 and 4 clones were resistant to atrazine and diuron, respectively.Abbreviations Atrazine 2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine - diuron 3-(3,4-dichlorophenyl)-1,1-dimethylurea - NEU N-ethyl-N-nitrosourea - PSII photosystem II     

Medicago truncatula,a model plant for studying the molecular genetics of theRhizobium-legume symbiosis

Medicago truncatula has all the characteristics required for a concerted analysis of nitrogen-fixing symbiosis withRhizobium using the tools of molecular biology, cellular biology and genetics.M. truncatula is a diploid and autogamous plant has a relatively small genome, and preliminary molecular analysis suggests that allelic heterozygosity is minimal compared with the cross-fertilising tetraploid alfalfa (Medicago sativa). TheM. truncatula cultivar Jemalong is nodulated by theRhizobium meliloti strain 2011, which has already served to define many of the bacterial genes involved in symbiosis with alfalfa. A genotype of Jemalong has been identified which can be regenerated after transformation byAgrobacterium, thus allowing the analysis ofin-vitro-modified genes in an homologous transgenic system. Finally, by virtue of the diploid, self-fertilising and genetically homogeneous character ofM. truncatula, it should be relatively straightforward to screen for recessive mutations in symbiotic genes, to carry out genetic analysis, and to construct an RFLP map for this plant.     

Temperature-dependent osmotic permeability in glycoproteion containing liposomes

The osmotic water outflow of large multilamellar liposomes containing ₁-acid glycoprotein was measured at a temperature near the lipid's phase transition temperature. The liposomes were formed from a mixture of DPPC, cholesterol and glycoprotein in molar ratios 100:20:1, by continuous sucrose density gradient centrifugation. These liposomes captured 35% of the radiolabeled glycoprotein. The temperature-dependent experiments showed that near phase transition temperature the initial rate of water outflow increased drastically in comparison with glycoprotein free liposomes incubated in buffer containing glycoprotein. We suggested that eventual a channel mechanism may be involved due to spontaneous incorporation of glycoprotein into the bilayer.     

Differential sensitivity to natural cell-mediated cytotoxicity of two rat colon adenocarcinoma variants differing in their tumorigenicity: identification of the effector cells as natural killer cells

Summary DHD/K12 TRb (PROb) and DHD/K12 TSb (REGb) are two cancer cell variants originating from the same rat colon adenocarcinoma. They differ in their tumorigenicity: when inoculated into syngeneic BDIX rats, PROb cells induce progressive tumors whereas REGb cells induce tumors which always regress. As previously described, there is an inverse relation between their tumorigenicity and their susceptibility to NCMC mediated by syngeneic spleen or peripheral blood lymphocytes: PROb cells are significantly less sensitive to NCMC than REGb cells. This suggests a role for NCMC in the regression of REGb tumors. In this work the BDIX NCMC effector cells active in vitro against REGb cells were identified as NK cells according to four criteria: (1) efficacy in a 4-h ⁵¹Cr release assay, (2) sensitivity to anti-asGM1 antibody plus complement, (3) LGL morphology, and (4) ability to bind with the same affinity REGb and YAC-1 cells. In spleen, these NK cells were heterogeneous with respect to their asGM1 surface density and their morphology. PROb cells were not lysed by these NK cells in a short-term cytotoxicity assay, but only in a 16-h assay. It was shown that PROb and REGb cells were bound with the same affinity by NK cells, thus they certainly differ in their ability to resist to NK lytic mechanisms. This difference could play a role in the different tumorigenicity of the two variants. Abbreviations used: NK, natural killer; NC, natural cytotoxic; NCMC, natural cell-mediated cytotoxicity; asGM1, asialo GM1; LL, large lymphocytes; LGL, large grnular lymphocytes; LAL, large agranular lymphocytes; PBMNC, peripheral blood mononuclear cells; E:T, effector to target cell ratio; C:H, cold to hot cell ratio; FBS, fetal bovine serum     

Serum copper,zinc levels,and copper

Serum copper and zinc levels were determined in 20 healthy women and in 100 women with gynecological tumors. Malignant and benign tumor cases were separated according to their postoperative, histopathological examinations. The stages of malignant and benign tumors were also established histologically. Seventy benign and 30 malignant genital tumors (carcinoma of cervix in situ, cervix, ovary endometrium, and vulva) of the patients were differentiated histopathologically. The serum Cu/Zn ratios of patients were increased significantly from the control group (0.32±0.35) to the benign group (1.22±0.63) and from the benign group to the malignant group (2.24±1.03). Nine of 30 malignant cases were determined as false negative (30%) and 15 of 70 benign cases were determined as false positive (14.2%) according to the serum Cu/Zn ratios of patients. Serum copper levels of 30 malignant and 10 benign tumor cases showed linear correlation with serum ceruloplasmin values.     

Structure and carcinogenicity of Dibenzo(c,g)carbazole derivatives

The carcinogenicity of several groups of carcinogens is evoked with particular reference to Dibenzo(c,g)carbazole derivatives. The activity of these derivatives is discussed with respect to their species and organ specificity. The enzymatic equipment is decisive as to whether the compounds formed can react with DNA or are simply detoxified and eliminated. All these carcinogens are complete carcinogens, i.e. they have the property of both initiation and promotion.