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At least 649 records · Page 36Linked to original sources

PubMed2006

Natural genetic transformation: A novel tool for efficient genetic engineering of the dairy bacterium Streptococcus thermophilus.

Streptococcus thermophilus is widely used for the manufacture of yoghurt and Swiss or Italian-type cheeses. These products have a market value of approximately 40 billion dollars per year, making S. thermophilus a species that has major economic importance. Even though the fermentation properties of this bacterium have been gradually improved by classical methods, there is great potential for further improvement through genetic engineering. Due to the recent publication of three complete genome sequences, it is now possible to use a rational approach for designing S. thermophilus starter strains with improved properties. Progress in this field, however, is hampered by a lack of genetic tools. Therefore, we developed a system, based on natural transformation, which makes genetic manipulations in S. thermophilus easy, rapid, and highly efficient. The efficiency of this novel tool should make it possible to construct food-grade mutants of S. thermophilus, opening up exciting new possibilities that should benefit consumers as well as the dairy industry.

DNA, Bacterial↗

PubMed1987

Measuring genetic stability in bacteria of potential use in genetic engineering.

Four commonly used conjugation techniques, colony cross streak (CCS), broth mating (BM), combined spread plate (CSP), and membrane filtration (MF), were compared with each other regarding reliability, sensitivity, and complexity in evaluating the transfer of conjugative plasmids. Five plasmids representing several incompatibility groups plus a variety of laboratory and environmental isolates were used as mating pairs. The suitability of each method was evaluated for use in a routine assessment of the genetic stability of genetically engineered microorganisms. By the CSP and MF techniques with laboratory strains such as Escherichia coli and Pseudomonas species as recipients, transconjugants were usually produced in 100% of the mating trials. However, when environmental strains isolated from plants and soil were used as recipients, transconjugants were detected in 100% of some crosses and in as little as 30% in other crosses depending on the plasmid and recipient used. In general, differences in the percentage of successful matings between the CSP and MF techniques compared with the BM and CCS techniques were not statistically significant at the P less than or equal to 0.05 level. Occasionally, certain mating pairs consistently produced transconjugants by CCS or BM but not by CSP or MF. Since any single conjugation mating technique is not completely reliable in detecting transconjugants, we have developed a combined mating technique which integrates the CCS, CSP, BM, and MF methods as a single procedure to assess the mobility of plasmid DNA of genetically engineered microorganisms.

Conjugation, Genetic↗

PubMed1995

Genetic elements of plant viruses as tools for genetic engineering.

Viruses have developed successful strategies for propagation at the expense of their host cells. Efficient gene expression, genome multiplication, and invasion of the host are enabled by virus-encoded genetic elements, many of which are well characterized. Sequences derived from plant DNA and RNA viruses can be used to control expression of other genes in vivo. The main groups of plant virus genetic elements useful in genetic engineering are reviewed, including the signals for DNA-dependent and RNA-dependent RNA synthesis, sequences on the virus mRNAs that enable translational control, and sequences that control processing and intracellular sorting of virus proteins. Use of plant viruses as extrachromosomal expression vectors is also discussed, along with the issue of their stability.

DNA Replication↗

PubMed2006

'Genetics home reference': helping patients understand the role of genetics in health and disease.

The surge of information generated by the Human Genome Project has left many health professionals and their patients struggling to understand the role of genetics in health and disease. To aid the lay public and health professionals, the US National Library of Medicine developed an online resource called 'Genetics Home Reference' (GHR), located at http://ghr.nlm.nih.gov/. Launched in April 2003, GHR's goal is to help the public interpret the health implications of the Human Genome Project. It bridges the clinical questions of consumers and the rich technical data emerging from the sequenced human genome. The GHR web site is designed for easy navigation among summaries for genetic conditions and the related gene(s) and chromosome(s). This design strategy enhances the user's appreciation of how genes, chromosomes, and conditions are interrelated.

Genetic Diseases, Inborn↗

PubMed2005

Community involvement in developing policies for genetic testing: assessing the interests and experiences of individuals affected by genetic conditions.

Because the introduction of genetic testing into clinical medicine and public health creates concerns for the welfare of individuals affected with genetic conditions, those individuals should have a role in policy decisions about testing. Mechanisms for promoting participation range from membership on advisory committees to community dialogues to surveys that provide evidence for supporting practice guidelines. Surveys can assess the attitudes and the experiences of members of an affected group and thus inform discussions about that community's concerns regarding the appropriate use of a genetic test. Results of a survey of individuals affected with inherited dwarfism show how data can be used in policy and clinical-practice contexts. Future research of affected communities' interests should be pursued so that underrepresented voices can be heard.

Achondroplasia↗

PubMed1994

Biometrical genetic analysis of blood pressure level in the genetically hypertensive mouse.

Hypertensive mice of the inbred strain BPH/2 were mated to mice of the inbred hypotensive BPL/1, and their hybrid offspring were crossed and intercrossed. The systolic blood pressures of the resulting ten populations were then subjected to a biometrical genetic analysis to determine the mode of inheritance of genes regulating blood pressure in these strains. It was found that the inheritance of elevated blood pressure was due, primarily, to the additive effects of three to five genes. There was no evidence that genetic dominance or epistasis were involved in the genetic control of blood pressure in these strains.

Animals↗

PubMed2000

Cancer genetics in primary care. When is genetic screening an option and when is it the standard of care?

In some families, predisposition to cancer is caused by a germline mutation in a single gene, which produces an autosomal dominant pattern of cancer transmission. Several hereditary cancer syndromes have been identified and for many of them, genetic testing is clinically available. Determining which patients are at risk for hereditary cancer begins by taking a complete family history. In particular, a three-generation family history and pedigree can provide valuable information for both patients and primary care physicians. When the history supports the possibility of hereditary cancer, a qualified genetic professional can assist with specific advice about testing and treatment options for the entire family. If pedigree analysis substantiates a heritable form of cancer, patients should be thoroughly informed about potential benefits, limitations, and risks of genetic screening and offered testing as appropriate. The ultimate goal is to reduce cancer morbidity and mortality through interventions that decrease cancer risk or increase early detection.

Adenomatous Polyposis Coli↗

PubMed1999

[Molecular genetic analysis of hobo mobile genetic element polymorphism in the genome of Drosophila melanogaster line subjected to long-term selection].

The distribution of mobile genetic element hobo was examined in Drosophila melanogaster lines HA (high male mating activity) and LA (low male mating activity) before and after their isogenization using Southern blot hybridization. The probe containing a full-size hobo copy was shown to produce polymorphic multilocus hybridization with chromosomal DNA. The polymorphism was line-specific. A comparison of hybridization patterns in isogenic and original lines showed that isogenization in dysgenic crosses resulted in the appearance of additional hobo localization sites in LA but not in HA. The hobo destabilization in the LA genome correlated with genetic instability and the ability to induce H-E hybrid dysgenesis. The results obtained are discussed in relation to the possible role of hobo in inducing genetic variability in lines with low male mating activity, which may counteract deleterious consequences of inbreeding and selection in the negative direction.

Animals↗

PubMed1999

Secretary's advisory committee on genetic testing: its emerging role in public policy deliberation on genetic tests.

The Secretary's Advisory Committee on Genetic Testing (SACGT) was established by the U.S. Secretary of Health and Human Services, Donna E. Shalala, to provide a public forum for the formulation of policy advice in the complex and growing area of genetic testing. After a careful nomination and selection process, the Secretary announced the appointment of thirteen advisors to the SACGT in June 1999. The first meeting of the SACGT was held June 30, 1999. This article describes the purpose, formation, and function of the SACGT. Before addressing these questions about the role of the SACGT, we first will explain what genetic testing is, how it is currently used, and what new uses it may be put to in the future.

Advisory Committees↗

PubMed1991

Innovations in human genetics education. Medical student elective in clinical genetics.

The fourth-year medical student elective in clinical genetics has been enhanced by the addition of a problem-solving project. The assignment requires students to pose and answer a practical question about a professionally relevant genetic problem. Exemplary questions and the details of the exercise are given. Six of 10 students choosing an elective in clinical genetics have undertaken the project. Their feedback suggests that the requirements of decision making, library research, discussion with consultants, and medical writing in a limited time period are beneficial additions to the standard elective.

Curriculum↗

PubMed1989

[Genetic variation and genetic diseases].

Detailed knowledge of the genetic make-up of individuals, revealed by examination of their DNA, is emerging as a significant component in medical diagnosis. Sometimes direct examination of DNA can determine whether a mutant gene is present or not. In other instances the genetic constitution of an individual can be inferred by use of genetic markers known to be close to the gene. The applications of this new level of knowledge are far reaching, extending to disease predisposition to several illness and responses to infectious agents. The use of DNA polymorphisms associated with linked DNA segments should permit diagnosis of hitherto undetectable disease states and also chromosomal localization of the loci responsible. The eventual isolation of the gene itself should lead to a better understanding of the molecular basis of inherited disease.

Chromosome Mapping↗

PubMed1989

[Genetic analysis of Streptomyces erythreus heteroclones. II. Determination of the distances between genetic loci on the map].

As a result of recombination experiments between auxotrophic mutants of S. erythreus BTCC2 haploid recombinants and heteroclones were isolated. A genetic map of S. erythreus, including 15 auxotrophic loci was constructed by genetic analysis of the segregants of the heteroclones obtained. The genetic distances between 7 key loci on the map were determined and the entire length of the map of about 105 standard recombination units was calculated.

Amino Acid Sequence↗

PubMed1987

[Genetic structure of aboriginal populations of northeastern USSR. VI. Correlations of genetic and geographic distances between populations and subpopulations].

Significant correlation of genetic distances (estimated for 17 polymorphic loci) between populations of Asia and Alaska Eskimos, coast and reindeer chuckchies, Kamchatka koryaks and Chuckotka even with geographic distances (r = 0.650; P less than 0.01) is shown. Also, significant correlation of genetic and geographic distances between 5 coast chuckchies subpopulations have been revealed (r = 0.871; P less than 0.001). The findings can indicate some ecological conditionality of population and subpopulation genetic structure's features.

Alaska↗

PubMed1995

[Comparative analysis of patterns of localization of mobile genetic elements in genetic selection experiments on Drosophila melanogaster].

A comparative selection-genetic analysis of three heterogeneous lines of Drosophila melanogaster with an interrupted longitudinal wing vein was performed. In the control line, riC, and two selection lines, riSP and riSN, overall patterns of localization of six families mobile genetic elements (MGE) (MGE) (MDG1, MDG2, MDG3, MDG4, copia, and 297) were compared. In all, the lines contained 220 sites (copies) in 153 segments of the Bridges' map. According to response to selection, six classes of sites were identified: strong positive (P), weak positive (p), neutral (n), weak negative (n), strong negative (N), and abnormal (A). More than 50% of the sites (P+N+p+n) were shown to respond to selection; the contrasting classes (P and N and p and n) counterbalanced each other. These sites are assumed to mark actual parts of the genome, where polygenes are located. In other words, more than 50% of the total number of the genome sites act as polygenes controlling this quantitative character and respond to selection. Pleiotropy of polygenes in such a system must be very high. 22.2% of sites are neutral (class 0); apparently, they do not mark polygenes. The remaining 21.8% of sites (class A) show an anomalous response to selection. They are assumed to mark the polygenes of another genetic system, which participated in the maintenance of homeostasis in the original line riC. On the basis of this evidence, the concept of oligogenes and polygenes is developed. Oligogenes and polygenes are genes that occupy respectively limiting and nonlimiting positions in systems of expression. Adaptive properties of oligogenes are evaluated first and evolve rapidly. Adaptive properties of polygenes are evaluated only with regard to their total set and are limited by oligogenes. Variation of polygenic systems is generated by polygenic combination and spontaneous transpositions and excisions of MGE.

Animals↗

PubMed1993

[Feasibility of establishing genetic homeostasis in human populations using a complex of genetic markers].

The information that we have about functional connection of different phenotypes of independent loci served for identification of their reciprocal behavior in cohorts differed in healthy status from the same population. Coefficients of correlation were computed between phenotypes according to the scheme: everyone with all in a Buryat, on the basis of the distribution of 17 genetic loci. Their space was transformed to a standardized one of eigenvectors. Calculation of the distances between genotypes was performed using the Euclidean formula. The same distances were estimated using an alternative formula of reverse cosine from correlation. It was determined: 1) subgroups of ecological risk and adaptive norm have peculiarities of phenotypical combinations; 2) the number of reliable correlations between phenotypes 2.5 times exceeded that in the adaptive part of the population as compared with unfavourable cohort (according to the health status); 3) the proportion of attractably connected phenotypes (the effect of their interaction) was higher than the corresponding repulsive connected ones (the effect of their repulsion) in the adaptive standard subgroup; 4) on the contrary, the proportion of repulsively connected phenotypes prevailed over the corresponding attractably associated ones in the ecological risk subgroup; 5) there were smaller genetic distances between phenotypes in the adaptive norm subgroup as compared with those in the ecological risk cohort. All these data permit to narrate about considerably greater functional balance of the studied portion of the genome in the clinically healthy subgroups that express the display of genetic homeostasis in complex discrete nonlinked characters. Interloci correlation between Hp and Cerumen systems in the three populations studied were obtained.

Adaptation, Physiological↗

PubMed1998

[Clinics for counseling on cancer genetics. Experiences with genetic studies and counseling on familial breast cancer and colorectal cancer].

Five to ten percent of cases of breast cancer and colorectal cancer are familial. These families can be divided into high-risk families and moderate-risk families. Cancer in high-risk families can often be explained by dominant inheritance of a gene causing increased susceptibility to cancer. There is a great demand for genetic counseling in these families, and the structure of and experiences from a familial cancer clinic at Odense University Hospital is described. The establishment of a familial cancer clinic involves three steps: 1) Identification of families with increased cancer susceptibility; 2) Molecular tests to identify gene carriers; 3) Clinical examinations for early detection of tumors. Achievement of these three steps requires the involvement of several medical specialties to ensure patient care. Experience with familial cancer clinics is still limited and the involvement of genetic testing and clinical examination programs at risk individuals are insufficiently examined. The rapidly improving techniques for genetic testing make it urgent that it is implemented as part of already established clinical programs.

Adult↗

PubMed2001

Predictive genetic testing in children.

Predictive genetic testing should only be performed on children if it is in their best interests. "Interests" include psychosocial elements. Predictive testing is performed on children when there are interventions to prevent disease or to detect and treat it early and it is necessary to begin these interventions in childhood. It is also performed for diseases known to commence in childhood. Predictive testing in children for adult-onset conditions for which there is no medical intervention is highly controversial. Competent children and adolescents can consent to predictive genetic testing. Predictive testing can result in harm, such as discrimination (eg, in insurance entitlement or employment) and stigmatisation. Predictive testing can have important non-medical benefits in terms of self-knowledge and life planning.

Australia↗

PubMed1982

Use of restriction fragment length polymorphisms for genetic counseling: population genetic considerations.

Two-locus population genetic models are analyzed to evaluate the utility of restriction fragment length polymorphisms for purposes of genetic counseling. It is shown that the linkage disequilibrium between a neutral marker and a tightly linked overdominant mutant will increase rapidly as the mutant moves to its polymorphic equilibrium. The linkage disequilibrium decays for deleterious recessive mutants. Two measures involving the linkage disequilibrium are investigated to determine how much information the transmission of the neutral marker provides about the transmission of the selected gene. In certain kinds of matings, where the parental two-locus genotypes and linkage phases are known, it is possible to determine whether or not a progeny is homozygous for the selected gene on the basis of the fetal genotype at the marker locus. A quantity of primary interest is the fraction of matings between individuals heterozygous for the selected gene in which exact diagnosis can be made in this way. The expected proportion of such matings, taken over all two-locus matings involving heterozygotes at the selected locus, is calculated as a function of the gene frequencies at the two loci and the linkage disequilibrium between them. This expected value is maximized when the linkage disequilibrium is at its maximum in absolute value. Fewer than half of all matings are informative if the linkage disequilibrium is small in magnitude or if the gene frequencies at the two loci are quite different. Consideration is also given to various conditional measures of association that may be useful when the parental two-locus genotypes are unknown. The results suggest that the utility of tightly linked neutral marker genes in predicting the transmission of a selected gene is generally less when selection acts against a recessive gene than for overdominant selection.

Base Sequence↗