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At least 1,009 records · Page 56Linked to original sources
PubMed2003

Recombinant congenic strains of mice: a new tool for the genetic dissection of efficacy and toxicity of adjuvants.

The efficacy of immunization of a vaccine depends on an antigen, an adjuvant, and on the expression of multiple genes in the host. The responsiveness of various strains of mice to adjuvants is therefore dependent on their genetic background present as a complex, multigenic trait similarly as in man. We have recently developed a gene-discovery platform, termed recombinant congenic strains (RCS), that greatly facilitates the dissection, localization and characterization of genes that mediate complex traits such as responsiveness to adjuvants. These recombinant congenic mice, which were constructed from two progenitor strains (A/J and C57BL/6) that are phenotypically different for several spontaneous or infectious diseases, were generated such that they carry 13.5% of the one genome in 85% of the other genome. The use of these RCS mice therefore enables a more efficient identification of genes that mediate the responsiveness of the adjuvant.

Adjuvants, Immunologic↗
PubMed2001

Monoclonal antibody-mediated manipulation as a tool for dissecting genetic pathways underlying specific embryonic processes.

The technology to produce monoclonal antibody (mAb) is one of mainstays supporting current biology. Identification and isolation of a specific molecule in situations where many other molecules coexist is the most popular way of using this technology. Some mAb can trigger or suppress the function of a given molecule, thus having a potential for use in manipulating developmental processes. A decade ago, we demonstrated that embryonic components of pigment cell development could be manipulated by injection of a mAb that inhibits the function of the c-Kit tyrosine kinase receptor (RTK) into pregnant mice. While we believe that no other methods were available at that time to freely trigger or suppress the function of such molecules as c-Kit, molecular genetic technologies enabling the same task have been developed recently. In this article, we want to give a general overview of our previous experience of using mAb for manipulating embryonic processes, and discuss the potential of this technology in the age of new molecular genetics.

Animals↗
PubMed1990

Entrapment vectors: a new tool for mammalian genetics.

The use of mouse embryonic stem (ES) cells has facilitated the creation of mouse strains carrying desired genetic alterations. Recently, "entrapment" vectors have been developed to identify and mutate genes active during embryogenesis. These vectors in combination with ES cells may provide an efficient screening strategy to find genes that control mouse development.

Animals↗
PubMed2004

The peptide nucleic acids (PNAs), powerful tools for molecular genetics and cytogenetics.

Peptide nucleic acids (PNAs) are synthetic mimics of DNA in which the deoxyribose phosphate backbone is replaced by a pseudo-peptide polymer to which the nucleobases are linked. PNAs hybridize with complementary DNAs or RNAs with remarkably high affinity and specificity, essentially because of their uncharged and flexible polyamide backbone. The unique physico-chemical properties of PNAs have led to the development of a variety of research assays, and over the last few years, the use of PNAs has proven their powerful usefulness in molecular biology procedures and diagnostic assays. The more recent applications of PNA involve their use as molecular hybridization probes. Thus, several sensitive and robust PNA-dependent methods have been designed for developing antigene and anticancer drugs, modulating PCR reactions, detecting genomic mutation or labelling chromosomes in situ.

Cytogenetics↗
PubMed2004

New tools for preimplantation genetic diagnosis of Huntington's disease and their clinical applications.

Huntington's disease (HD) is a late-onset neurodegenerative disorder transmitted as an autosomal dominant trait. The causative mutation was characterised in 1993. For HD carriers willing to create a family, prenatal diagnosis (PND) or preimplantation genetic diagnosis (PGD) based on the mutation identification can be offered. For at-risk persons who do not want to undergo presymptomatic testing (PT), an exclusion test can be proposed. With such a test, only foetuses or embryos that inherit an allele from the unaffected grandparent are considered as unaffected. In cases of PND, if the foetus has one allele of the affected grandparent, termination of pregnancy is proposed. In cases of PGD, only not at-risk embryos are transferred. Since the beginning of our PGD activity, we have had 43 PGD referrals for HD, of which 24 were from patients who know their genetic status and 19 from patients who do not wish to perform PT. We have developed 12 multiplex fluorescent PCR protocols applied at the single-cell level for PGD, some of which target the CAG repeat while others use two different polymorphic microsatellites. We present here these different protocols and their clinical applications, as well as the characterisation and use of a new highly polymorphic intragenic marker. Between May 2001 and December 2003, 39 PGD cycles have been performed for 17 couples, 11 of whom had a known genetic status and six who did not wish to perform PT, resulting in four pregnancies.

Female↗
PubMed2002

Congenic rat strains are important tools for the genetic dissection of essential hypertension.

The identification of mutated genes and the characterization of disease pathways in monogenetic forms of human arterial hypertension has been very successful during the past decade, although only little progress has been made with regard to the genetic analysis of essential hypertension. Inbred rat strains that display hypertension as an inherited trait represent an attractive substitute for the dissection of the polygenetic basis of human essential hypertension. The power of studying these inbred models with natural allelic variation is that each strain can be thought of as a different subtype of essential hypertension. Thus, to study the genetics of hypertension using a potpourri of inbred hypertensive rat strains may help to identify a set of genes that can give rise to hypertension in the heterogeneous clinical situation of essential hypertension. Indeed, multiple blood pressure quantitative trait loci (QTL) have been identified in the rat genome and a few of those have been implicated in the human disease by homology mapping already. Here, we discuss the role of congenic breeding strategies to further dissect the genetics of hypertension in the rat. Based on recent accomplishments it can be anticipated that by using congenic strains, the genetic sifting of the collection of blood pressure QTLs identified so far will lead to the identification of additional and new candidate genes. This will open the possibility for the development of new diagnostic and therapeutic means contributing to a better control of human essential hypertension.

Animals↗
PubMed1997

DISTREE: a tool for estimating genetic distances between aligned DNA sequences.

MOTIVATION: Substitution rates estimated from aligned DNA data can be used as genetic distances to investigate the phylogenetic relationship of those sequences. For this purpose, a Markov model of nucleotide substitution has to be assumed that describes this process most adequately. RESULTS: A program is presented that estimates substitution rates and their standard errors for a variety of Markov models. The model introduced by Hasegawa et al. (J. Mol. Evol., 22, 160-174, 1985) is the only one for which distances and standard deviations need to be calculated numerically, since analytical formulae cannot be derived. Each model is implemented in two different variants: (i) assuming rate homogeneity or (ii) starting from Gamma-distributed substitution rates across sequence sites. The estimation of heterogeneous substitution rates is based on a method suggested by Tamura and Nei (Mol. Biol. Evol., 10, 512-526, 1993). All required parameters are estimated from sequence data, hence the user is not asked to supply any additional input. One goal of the program is to support the user when choosing a particular model that describes most adequately the evolution of the given data set. For this purpose, a more detailed analysis of this model fit is provided. Phylogenetic trees reconstructed from the inferred distances using the neighbor-joining algorithm are also available.

Algorithms↗
PubMed2000

Single nucleotide polymorphisms as tools in human genetics.

The development of detailed single nucleotide polymorphism (SNP) maps of the human genome coupled with high-throughput genotyping technologies may allow us to unravel complex genetic traits, such as multifactorial disease or drug response, over the next few years. Here we describe the current efforts to identify and characterize the large numbers of SNPs required and discuss the practicalities of association studies for the identification of genes involved in complex traits.

Genetics, Medical↗
PubMed2002

The cpcB-cpcA locus as a tool for the genetic characterization of the genus Arthrospira (Cyanobacteria): evidence for horizontal transfer.

To investigate the genetic diversity of the genus Arthrospira and to compare it with other cyanobacteria, sequences of 670 nt from the phycocyanin operon were determined for 23 natural, cultivated or commercial strains of Arthrospira and compared with sequences from 20 other non-Arthrospira cyanobacterial strains. The sequenced DNA fragment comprises the last 255 nt of cpcB, the cpcB-cpcA spacer and the first 304 nt of cpcA. The resulting phylogenetic tree confirms that the genus Arthrospira is not related to Spirulina. So far, cpcB-cpcA data suggest that the closest relative of Arthrospira is Planktothrix. Based on this locus, the genus Arthrospira consists of three genetically clustered lineages. However, the distribution of nucleotide substitutions indicates that these three lineages are not the result of a simple cladogenesis characterized by the accumulation of independent substitutions. Instead, the observed clustering is the result of horizontal transfers of blocks of sequences. Analysis of the distribution of substitutions in the sequenced fragment indicates a point of intragenic recombination close to the stop codon of cpcB. The capacity of exchange of genetic material among strains probably explains why morphology and geographical origin do not correlate with the cpcB-cpcA clusters. Nevertheless, this study shows for the first time that the genus Arthrospira, represented here by cultivated and wild specimens, is clearly monophyletic. Moreover, the cpcB-cpcA DNA fragment, comprising both highly and moderately variable regions, allows (1) a strict differentiation of the taxon Arthrospira from other cyanobacteria (using the coding regions only) and (2) the study of relationships inside Arthrospira (using both the coding and non-coding regions).

Bacterial Proteins↗
PubMed2006

Use of survival analysis as a tool for the genetic improvement of age at first conception in Nellore cattle.

Restricted breeding seasons in beef cattle lead to censoring of reproductive data. In this paper, age at first conception (AFC) of Nellore females exposed to the sires for the first time between 11 and 16 months of age, was studied aiming to verify the possibility of genetically advance sexual precocity using a survival model. The final data set contained 6699 records of AFC in days. Records of females that did not calve in the next year following exposure to the sire were considered censored (77.5% of total). The model used was a Weibull mixed survival model including effects of contemporary groups, period (fixed) and animal (random). The effect of the contemporary groups on AFC was important (p < 0.01). Heritabilities were 0.51 and 0.76 in logarithmic and original scales respectively. Results indicate that it is possible to genetically advance sexual precocity, using the outcome of survival analysis of AFC as selection criterion. They also suggest that improvements of the environment could advance sexual precocity too, thus an adequate pregnancy rate for farmers could quickly be achieved.

Age Factors↗