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At least 181 records · Page 10Linked to original sources
PubMed1985

Protoplast fusion as a tool for genetic analysis in Cephalosporium acremonium.

Protoplasts of nutritionally complementary strains of Cephalosporium acremonium were fused and plated onto media which supressed the growth of both parents. The regenerating colonies were used for genetic analysis and were found to be of two types, stable haploid recombinants and unstable heterozygotes (aneuploids and/or diploids). Analysis of these colonies provided evidence for eight linkage groups and a relatively high rate of mitotic crossing-over. The gene order for three of the markers on one linkage group was also determined.

Acremonium↗
PubMed2002

Transformation of the cyanobacterium Synechocystis sp. PCC 6803 as a tool for genetic mapping: optimization of efficiency.

The cyanobacterium Synechocystis sp. PCC 6803 is transformable at high efficiency and integrates DNA by homologous double recombination. However, several genetic mapping procedures depend on the ability to generate transformants even with very small amounts of added DNA. This study is aimed at optimizing the transformation efficiency at limiting concentrations of exogenous DNA. The transformation efficiency showed little sensitivity to experimental conditions. Transformation with circular plasmid DNA was found to be no more than 30% more efficient than with linearized plasmid DNA. The efficiency of transformation remained essentially the same in the presence of competing DNA, indicating that the capacity of DNA uptake by the cells is not limiting. The incubation time of cells with DNA before plating (0-8 h) affected the transformation efficiency by up to 3-fold. Only minor changes in the efficiency were observed as a function of the presence of a membrane filter on the plate or the presence of TAE or TBE gel buffer residues in the transformation mixture. However, transformability of the host strain of Synechocystis sp. PCC 6803 was increased by two orders of magnitude if the sll1354 gene encoding the exonuclease RecJ was deleted. Therefore, the transformation efficiency of Synechocystis sp. PCC 6803 with exogenous DNA appears to be determined primarily by intracellular processes such as the efficiency of DNA processing and homologous recombination.

Bacterial Proteins↗
PubMed1998

Characterization of genes involved in biosynthesis of a novel antibiotic from Burkholderia cepacia BC11 and their role in biological control of Rhizoctonia solani.

Genetic manipulation of fluorescent pseudomonads has provided major insight into their production of antifungal molecules and their role in biological control of plant disease. Burkholderia cepacia also produces antifungal activities, but its biological control activity is much less well characterized, in part due to difficulties in applying genetic tools. Here we report genetic and biochemical characterization of a soil isolate of B. cepacia relating to its production of an unusual antibiotic that is very active against a variety of soil fungi. Purification and preliminary structural analyses suggest that this antibiotic (called AFC-BC11) is a novel lipopeptide associated largely with the cell membrane. Analysis of conditions for optimal production of AFC-BC11 indicated stringent environmental regulation of its synthesis. Furthermore, we show that production of AFC-BC11 is largely responsible for the ability of B. cepacia BC11 to effectively control the damping-off of cotton caused by the fungal pathogen Rhizoctonia solani in a gnotobiotic system. Using Tn5 mutagenesis, we identified, cloned, and characterized a region of the genome of strain BC11 that is required for production of this antifungal metabolite. DNA sequence analysis suggested that this region encodes proteins directly involved in the production of a nonribosomally synthesized lipopeptide.

Amino Acid Sequence↗
PubMed2001

Nickel-resistance-based minitransposons: new tools for genetic manipulation of environmental bacteria.

The ncc and nre nickel resistance determinants from Ralstonia eutropha-like strain 31A were used to construct mini-Tn5 transposons. Broad host expression of nickel resistance was observed for the nre minitransposons in members of the alpha, beta, and gamma subclasses of the Proteobacteria, while the ncc minitransposons expressed nickel resistance only in R. eutropha-like strains.

Conjugation, Genetic↗
PubMed1999

Risk estimation as a decision-making tool for genetic analysis of the breast cancer susceptibility genes. EC Demonstration Project on Familial Breast Cancer.

For genetic counselling of a woman on familial breast cancer, an accurate evaluation of the probability that she carries a germ-line mutation is needed to assist in making decisions about genetic-testing. We used data from eight collaborating centres comprising 618 families (346 breast cancer only, 239 breast or ovarian cancer) recruited as research families or counselled for familial breast cancer, representing a broad range of family structures. Screening was performed in affected women from 618 families for germ-line mutations in BRCA1 and in 176 families for BRCA2 mutations, using different methods including SSCP, CSGE, DGGE, FAMA and PTT analysis followed by direct sequencing. Germ-line BRCA1 mutations were detected in 132 families and BRCA2 mutations in 16 families. The probability of being a carrier of a dominant breast cancer gene was calculated for the screened individual under the established genetic model for breast cancer susceptibility, first, with parameters for age-specific penetrances for breast cancer only [7] and, second, with age-specific penetrances for ovarian cancer in addition [20]. Our results indicate that the estimated probability of carrying a dominant breast cancer gene gives a direct measure of the likelihood of detecting mutations in BRCA1 and BRCA2. For breast/ovarian cancer families, the genetic model according to Narod et al. [20] is preferable for calculating the proband's genetic risk, and gives detection rates that indicate a 50% sensitivity of the gene test. Due to the incomplete BRCA2 screening of the families, we cannot yet draw any conclusions with respect to the breast cancer only families.

Adult↗
PubMed1990

Crossbreeding as a tool for genetic improvement of chickens in suboptimum environments.

A 2-phase crossbreeding study was undertaken to explore prospects of improving the performance of chickens under extensive production conditions in Tanzania. The first phase was carried out under reasonably good feeding and housing conditions and involved one imported meat and egg type each as well as a local breed and their crosses. In the second phase, 15 genetic groups with graded proportions of inheritance from the 3 parental breeds were compared for their performance under relatively poor conditions of feeding and general management. The results revealed that under good production conditions the performance in a particular trait increased with increasing levels of inheritance from the exotic breed which had been developed mainly for that trait. Under poor management conditions, the trend was rather obscure, with the superiority of germ plasma from the exotic breeds expressed in the crosses rather than in the parental breeds. The disparity between the results obtained in the two phases is attributed to genotype x environmental interaction, heterosis, heterosis x environment interaction, and maternal and sex-linked influences. It is concluded that the genetic disposition of the high performers should be adapted to the local production conditions by forming synthetic breeds based on crossbreeding.

Animals↗
PubMed1988

Molecular biology as a tool for genetic research in hypertension: application to the renin gene.

Hypertension is a multifactorial and heterogeneous disease caused by the addition of environmental and genetic factors. Heritability of systolic and diastolic blood pressure has been well established. Among 6,594 hypertensive patients studied in our clinic, 42% had a history of hypertension in one of their parents and in this group, 13% also had a hypertensive sibling. Anamnestic but not clinical features of patients with familial hypertension slightly differ from patients without familial hypertension. A general strategy is proposed to test the hypothesis that genes known to regulate blood pressure are also responsible for liability to hypertension. In a preliminary report, a study of the TaqI polymorphism of the human renin gene did not reveal a significant difference between hypertensive patients with a family history of hypertension and normotensive controls. A linkage study with DNA markers in informative families is also proposed as an alternative.

Humans↗
PubMed1995

Chromosome 8 congenic strains: tools for genetic analysis of limb malformation, plasma triglycerides, and blood pressure in the rat.

Congenic strains with the polydactyly-luxate syndrome (PLS), the BN.lx and Lew.lx, were originally derived to study the expression and mode of inheritance of the lx mutant gene on rat chromosome 8. The BN.lx PLS congenic strain together with the spontaneously hypertensive SHR strain served as progenitors for the production of the HXB/BXH recombinant inbred (RI) strains. One of the RI strains, the BXH11, carrying PLS was used for the transfer of PLS determining lx allele onto the SHR strain genetic background. Using PCR analysis, differential segments of chromosome 8 of BN.lx and SHR.lx congenic strains were described and shown to carry also genes associated with blood pressure and plasma triglyceride regulation. Possible experimental exploitation of chromosome 8 congenic strains in these respects is thus discussed.

Animals↗