Search PubMedSearch

PubMed · 7896288

Predicting progress in directed mapping projects.

Abstract

Several recent mapping efforts have used so-called "directed" approaches to construct their maps. However, most, but not all, published methods for modeling the progress in physical mapping projects have been focused on random approaches, such as bottom-up fingerprinting and STS-content mapping. In addition, those few efforts that did model directed approaches used methods that required assuming that all insert lengths were the same. This assumption is unnecessary. Using properties of stationary processes, one can derive simple asymptotic formulas that apply equally to constant and variable clone lengths. Also, in the case of constant clone lengths, these results are equivalent to, and extend, those published results for directed mapping derived by other methods. Simulations show that these methods provide estimates well within the limits of uncertainty inherent in any mapping project.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

D O Nelson, T P Speed. 1994-11-01. Predicting progress in directed mapping projects.. https://doi.org/10.1006/geno.1994.1580

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Mitotic karyotyping and FISH mapping of the gender-specific locus indicate an advanced XY system in Hippophae rhamnoides.

Hippophae rhamnoides ssp. turkestanica, a subdioecious plant inhabiting the cold desert of the Indian Himalaya, has gained immense recognition for its nutritional and medicinal values. In recent years, the plant species has proven to be a suitable system to understand the evolution of dioecy. Despite its biological significance, the cytogenetics of this dioecious plant is unclear due to various conflicting accounts of its X-Y chromosome system, particularly the length of Y-chromosome. In this study, we resolved these ambiguities through comprehensive cytogenetic analyses across diverse western Himalayan populations. Using morphometric analysis and fluorescence in situ hybridization (FISH) with a gender-specific marker (HRMSSR), we confirmed homomorphic XX chromosomes in females and heteromorphic sex-chromosomes in males with a notably smaller Y-chromosome. The investigation also revealed a predominant somatic chromosome number of 2n = 24, although minor deviations (2n = 18, 20, 22) appeared at the seed level. These findings highlight an evolutionarily advanced sex-chromosome system. This first detailed cytogenetic investigation of Himalayan Seabuckthorn provides critical insights into the chromosomal architecture, laying a crucial foundation for future evolutionary, genomic, and conservation studies in the species.

Chromosome Mapping

Physical mapping of the chromosome 7 breakpoint region in an SLOS patient with t(7;20) (q32.1;q13.2).

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder characterized by multiple congenital anomalies and mental retardation. SLOS has an associated defect in cholesterol biosynthesis, but the molecular genetic basis of this condition has not yet been elucidated. Previously our group reported a patient with a de novo balanced translocation [t(7;20)(q32.1;q13.2)] fitting the clinical and biochemical profile of SLOS. Employing fluorescence in situ hybridization (FISH), a 1.8 Mb chromosome 7-specific yeast artificial chromosome (YAC) was identified which spanned the translocation breakpoint in the reported patient. The following is an update of the on-going pursuit to physically and genetically map the region further, as well as the establishment of candidate genes in the 7q32.1 breakpoint region.

Chromosome Mapping

Toward cloning of a novel ataxia gene: refined assignment and physical map of the IOSCA locus (SCA8) on 10q24.

Infantile onset spinocerebellar ataxia (IOSCA) is a progressive neurological disorder of unknown etiology. It is inherited as an autosomal recessive trait and has so far been reported in just 19 Finnish patients in 13 separate families. We have previously assigned the IOSCA locus (HGMW-approved symbol SCA8) to chromosome 10q, where no previously identified ataxia loci are located. Haplotype analysis combined with genealogical data provided evidence that all the IOSCA cases in Finland originate from a single 30- to 40-generation-old founder mutation. By analyzing extended disease haplotypes observed today, the IOSCA locus can now be restricted to a region between two adjacent microsatellites, D10S192 and D10S1265, with no genetic intermarker distance. We have constructed a detailed physical map of this 270-kb IOSCA region and cytogenetically localized it to 10q24. We have also assigned two previously known genes, PAX2 and CYP17, more precisely into this region, but the sequence analysis of coding regions of these two genes has not revealed mutations in an IOSCA patient. The obtained long-range clones will form the basis for the isolation of a novel ataxia gene.

Chromosome Mapping