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.     

Mapping of Col3a1 and Col6a3 to proximal murine chromosome 1 identifies conserved linkage of structural protein genes between murine chromosome 1 and human chromosome 2q

We have investigated the degree of synteny between the long arm (q) of human chromosome 2 and the proximal portion of mouse chromosome 1. To define the limits of synteny, we have determined whether mouse homologs of seven human genes mapping to chromosome 2q cosegregated with anchor loci on mouse chromosome 1. The loci investigated were NEB/Neb, ELN/Eln, COL3A1/Col3a1, CRYG/Len-2, FN1/Fn-1, VIL/Vil, and COL6A3/Col6a3. Ren-1,2 and Acrg were included as two proximal mouse chromosome 1 anchor loci. The segregation of restriction fragment length polymorphisms at these loci was analyzed in the progeny of Mus spretus x C57BL/6J hybrids backcrossed to the C57BL/6J inbred strain. We found that five of the structural protein loci and the two anchor loci form a linkage group on proximal murine chromosome 1. The proposed gene order of this group of linked markers is centromere - Col3a1 - Len-2-Fn-1-Vil-Acrg-Col6a3-Ren1,2. Neb and Eln are linked neither to each other nor to any other marker on proximal mouse chromosome 1. Therefore, the mouse loci Col3a1 and Col6a3 are identified as flanking markers of the linkage group of structural protein loci. The estimated genetic map distances are Col3a1-13.3 cM-Len-2-3.4 cM-Fn-1-3.8 cM-Vil-9.6 cM-Acrg-2.1 cM-Col6a3-18.3 cM-Ren1,2. The available map information for human chromosome 2q markers and mouse chromosome 1 markers presented here tentatively identifies Col3a1 and Col6a3 as the border markers that define the limits of the syntenic chromosome segment. The order of mouse genes on chromosome 1 and their human homologs on chromosome 2q also appears to be conserved, suggesting that mapping of murine genes on the conserved segment may be useful to predict gene order in man.     

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.     

Chromium in plants

Chromium is an essential trace element and is associated with some biological pathways, especially with glucose tolerance. For these reasons, we decided to determine the concentration of chromium in two sets of Brazilian medicinal plants. The first group consisted of plants that are considered as antidiabetic, whereas the second included plants that do not have this therapeutic property. The concentration of chromium was determined by flameless atomic absorption. All the plants analyzed contain chromium in the normal range for this element, but the hypoglycemic plants contain more chromium than the others (1–4 μg/g compared to 0.5–1.5 μg/g).