Chromosomal Location Of Gene Research Articles

How obesity develops: insights from the new biology.

Molecular and genetic studies of animal models have identified numerous genes that may cause or contribute to the development of obesity. They have also provided significant insight into the peripheral and central pathways that control energy intake and expenditure. Genetic studies of families and populations have generated useful information on genes and mutations associated with or linked to obesity, body fat distribution, and other relevant phenotypes. This information, combined with knowledge of the chromosomal location of genes identified from animal studies, has made it possible to identify specific mutations that contribute to the development of obesity in humans.

Antibodies to N-terminal Peptides of Low MrSubunits of Wheat Glutenin. II. Detection of Subunits Encoded by Different Loci

A panel of anti-peptide antibodies specific for each of the different N-terminal sequence types of B- and C-low molecular mass glutenin subunits (L MrGS) were utilised in immunoblotting studies to identify the chromosomal location of genes encoding different sequences and to characterise the allelic variation of the encoding loci. The MET-type sequences were predominantly found among the B- subunits, while the α- and γ- sequences predominated in the C- subunits. The quantitatively major SHIPGLERPS sequence was found in both the B- and C- mobility regions. Using either biotypes in the cultivar, Aroona or genetic lines containing double rye chromosome 1 substitutions and thus expressing only single LMr GS alleles, the sequences were determined for most of the major polypeptides expressed by each LMr GS allele. The L MrGS from different genomes encoded different numbers of each sequence type. Furthermore, different polypeptides within a particular «block» of subunits encoded by a given allele often had differing N-terminal sequences. However, subunits of similar electrophoretic mobilities encoded by different alleles at each locus usually had identical N-terminal sequences, suggesting that they may instead differ in the number of repeats. In Chinese Spring, genes encoding the SHIPGLERPS and METSHIPGL sequence types were predominantly present on chromosomes 1B and 1D, while the related METSRVPGL sequence was only encoded on 1D. In contrast, the METSCIPGL, α- and γ-sequences were encoded on each of chromosomes 1A, 1B and 1D. Several different electrophoretic and immunoblotting approaches using null lines suggested that some of the α-type L MrGS may also be encoded by group 6 chromosomes, particularly 6D. The anti- SHIPGLERPS antibody also recognised chromosome 1B encoded β-, γ- and ω-gliadins, while the anti-METSRVPGL antibody recognised 1D encoded α- and β-gliadins. The absence of sequences within the major gliadin families that are highly homologous to the latter two N-terminal L MrGS sequences may suggest that some monomeric L MrGS could exist within the electrophoretically-resolved gliadins. These antibodies will provide valuable reagents for the study of the roles of particular L MrGS families in the structure and function of the glutenin macropolymer, the role of different LMr GS types in determining the influence of allelic variation of L MrGS composition on dough properties, and potentially in the development of diagnostics for these flour components.

Chromosome location of genes affecting polyphenol oxidase activity in seeds of common and durum wheat

This study used cytogenetic stocks to investigate the chromosomal location of genes responsible for polyphenol oxidase (PPO) activity in common and durum wheat seeds. Substitution lines of chromosome 2A of hexaploid varieties ‘Cheyenne’, ‘Thatcher’ and ‘Timstein’ in ‘Chinese Spring’ showed significantly higher PPO activity than all other substitution lines of the same variety, with the exception of substitutions of ‘Cheyenne’ chromosome 3A and ‘Thatcher’ chromosome 4B. Substitution lines of chromosome 2A of Triticum turgidum var. dicoccoides and of chromosome 2D of ‘Chinese Spring’ into the tetraploid variety ‘Langdon’ showed a significant increase in PPO activity relative to all other substitution lines in Langdon. The gene(s) responsible for high PPO activity in chromosome 2D from ‘Chinese Spring’ was mapped on the long arm within a deletion that represents 24% of the distal part of the arm. This study shows that genes located in homoeologous group 2 play a major role in the activity of PPO in wheat.

Chromosomal location effects on gene sequence evolution in mammals

Background: Nucleotide substitution rates and G + C content vary considerably among mammalian genes. It has been proposed that the mammalian genome comprises a mosaic of regions – termed isochores – with differing G + C content. The regional variation in gene G + C content might therefore be a reflection of the isochore structure of chromosomes, but the factors influencing the variation of nucleotide substitution rate are still open to question.Results: To examine whether nucleotide substitution rates and gene G + C content are influenced by the chromosomal location of genes, we compared human and murid (mouse or rat) orthologues known to belong to one of the chromosomal (autosomal) segments conserved between these species. Multiple members of gene families were excluded from the dataset. Sets of neighbouring genes were defined as those lying within 1 centiMorgan (cM) of each other on the mouse genetic map. For both synonymous substitution rates and G + C content at silent sites, neighbouring genes were found to be significantly more similar to each other than sets of genes randomly drawn from the dataset. Moreover, we demonstrated that the regional similarities in G + C content (isochores) and synonymous substitution rate were independent of each other.Conclusions: Our results provide the first substantial statistical evidence for the existence of a regional variation in the synonymous substitution rate within the mammalian genome, indicating that different chromosomal regions evolve at different rates. This regional phenomenon which shapes gene evolution could reflect the existence of ‘evolutionary rate units’ along the chromosome.

Unc-45 gene of Caenorhabditis elegans encodes a muscle-specific tetratricopeptide repeat-containing protein.

The unc-45 gene of the nematode, Caenorhabditis elegans, is essential for muscle organization and embryonic development. Genetic evidence suggests the unc-45 gene product controls muscle thick filament assembly. We report here on the determination of the gene's chromosomal location and the isolation and sequencing of its cDNA. The amino terminus of the predicted unc-45 protein contains three tandem repeats that belong in the tetratricopeptide repeat family. Tetratricopeptide motifs have been shown to be involved in protein interactions, and some of the closest homologues have chaperone-like activity. The carboxy terminus of the protein has homology with the related fungal proteins, CRO1 and She4p, which have been postulated to play a role in assembly of or interactions with a cytoplasmic myosin. We have also determined the sequence of the homologous gene from C. briggsae, which demonstrates a high level of conservation. We show that the unc-45 gene promoter can drive reporter gene expression, which is limited to muscle tissues (pharyngeal, body wall, vulval, and anal muscles), consistent with a role for the unc-45 gene in muscle development or function.

Reciprocal chromosome painting shows that genomic rearrangement between rat and mouse proceeds ten times faster than between humans and cats

Reciprocal chromosome painting between mouse and rat using complete chromosome probe sets of both species permitted us to assign the chromosomal homology between these rodents. The comparative gene mapping data and chromosome painting have a better than 90% correspondence. The reciprocal painting results graphically show that mouse and rat have strikingly different karyotypes. At least 14 translocations have occurred in the 10–20 million years of evolution that separates these two species. The evolutionary rate of chromosome translocations between these two rodents appears to be up to 10 times greater than that found between humans and cats, or between humans and chimpanzees, where over the last 5–6 million years just one translocation has occurred. Outgroup comparison shows that the mouse genome has incorporated at least three times the amount of interchromosomal rearrangements compared to the rat genome. The utility of chromosome painting was also illustrated by the assignment of two new chromosome homologies between rat and mouse unsuspected by gene mapping: between mouse 11 and rat 20 and between mouse 17 and rat 6. We conclude that reciprocal chromosome painting is a powerful method, which can be used with confidence to chart the genome and predict the chromosome location of genes. Reciprocal painting combined with gene mapping data will allow the construction of large-scale comparative chromosome maps between placental mammals and perhaps other animals.

Chromosome location of genes encoding human blood groups

The chromosomal locations of genes controlling the expression of some 200 antigens constituting the 23 established human blood group systems have been reviewed. Twenty-one of the these genes are located on 12 autosomes, and two are located on the X chromosome. Refined chromosomal positions, to a single cytogenetically distinguishable band, have been established for 13 of the 23 genes. For the remainder, continued investigation will achieve the same result. The genes (RD, MER2, and OK) controlling the expression of one low-incidence and two high-incidence erythrocyte antigens have also been presented. Of these, OK is the most likely candidate for blood group system status, because its chromosomal location distinguishes it from all established system genes except LE and LW, and, the product of the OK gene is different from those of LE and LW (Table 3). This issue will be considered at the next meeting (scheduled for July 1998) of the ISBT Working Party. Alternatively, RD and MER2 are not good candidates for blood group system status because RD and MER2 reside in chromosomal regions containing genes for other blood group systems. In addition, the products of RD and SC have similar biochemical characteristics, and the product of MER2 has not yet been defined (Table 3). The challenge remaining for blood group scientists is characterization of genes that control expression of the approximately 50 other known erythrocyte antigens. Most of these are members of the ISBT's 700 (low-incidence) or 901 (high-incidence) series. Because the current genetic information for each of these antigens (attained by serologic investigation) varies considerably, future studies will have to rely on "tools" from related disciplines to provide the additional information. Use of resources such as molecular biological protocols and GBD should facilitate the effort.

Chromosomal location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L. em Thell.). 5. Alleles at the Pm1 locus

The chromosomal location and genetic characterization of powdery mildew resistance genes were determined in the common wheat lines MocZlatka, Weihenstephan Stamm M1N and in a resistant line of Triticum aestivum ssp. spelta var. duhamelianum. Monosomic analyses revealed that one major dominant gene is located on chromosome 7A in each of the lines tested. Allelism tests with Pm1 in the backcross-derived line Axminster/8*Cc on 7A indicated that the resistance genes are alleles at the Pm1 locus. These alleles are now designated Pm1a in line Axminster/8*Cc, Pm1b in MocZlatka, Pm1c in Weihenstephan Stamm M1N, and Pm1d in T. spelta var. duhamelianum, respectively.

Electrophoretic karyotypes and genome sizing of the pathogenic fungus Paracoccidioides brasiliensis.

Here we present the karyotype analysis and genome sizing of Paracoccidioides brasiliensis, a pathogen refractory to conventional genetic analysis. We have established pulsed-field gel electrophoresis (PFGE) conditions to resolve the high-molecular-weight chromosomal bands of two clinical isolates of P. brasiliensis. Both isolates showed four megabase-sized bands, ranging from 2.0 to 10.0 Mbp. Significant differences in chromosome sizes and in the chromosomal location of genes for the gp43 antigen and chitin synthase were found. Different technical approaches were employed to estimate the DNA content and to define the ploidy of P. brasiliensis. An estimated genome size in the range of 45.7 to 60.9 Mbp was provided by the analysis of data generated by measuring the amplitude of fluorescence intensity of DAPI (4',6-diamidino-2-phenylindole)-stained nuclei (by confocal microscopy). The nuclear genome size estimated by confocal microscopy is twice that estimated by the average sum of the molecular weight of chromosome-sized DNA molecules by PFGE, suggesting that each separated P. brasiliensis chromosomal band is diploid.

Chromosomal location of genes for resistance to Puccinia striiformis in the wheat line TP1295 selected from the cross of Soissonais-Desprez with Lemhi

Crosses of a wheat line TP1295 with the cultivar Chinese Spring monosomic series were used to locate, on chromosome 1D, a major gene for resistance to isolate WYR 85-22 of race 6E0 of Puccinia striiformis. The gene is designated as Yr25 and is probably present in several of the cultivars currently widely used for differentiating races of this pathogen. The expression of the gene was modified by the environment and by at least one minor gene which may be located on chromosome 6A. In F2 and F3 generations from a cross between TP1295 and euploid Chinese Spring, a wide range of variation in infection type (IT) was observed. This precluded the classification of the plants as either resistant or susceptible, so they were assigned to 6 classes and analyzed by factorial correspondence analysis and non-hierarchical classification. When all F3 plants in a family were fully resistant, like TP1295 itself (IT ;), both Yr25 and the modifying gene were assumed to be present and homozygous. In environments favourable to expression of the gene, families thought to carry Yr25 alone had a distribution of ITs from fully resistant (IT ;) to intermediate (IT 2, rarely 3 or 3+). This F3 analysis indicated that use of IT data alone, in the monosomic analysis, would not reveal the chromosomal location of the genes and that chromosome counting of numerous plants was necessary. As well as indicating the chromosomes carrying the genes for resistance to isolate WYR 85-22, the data showed that plants monosomic for chromosomes 5B and 5D were more resistant than the corresponding disomics, indicating that these chromosomes promote susceptibility and supporting other evidence of the effects of these chromosomes on yellow rust resistance.

Chromosomal location of genes for supernumerary spikelet in bread wheat

The supernumerary spikelet (SS) character of bread wheat (Triticum aestivum L.) is an abnormal spike morphology expressing extra spikelets per spike. Chromosomal location of the genes for the SS character in the bread wheat line, Yupi Branching was determined by monosomic analysis. The normal-spiked bread wheat Chinese Spring monosomic series were used as testing lines. Data indicated that chromosomes 2D, 4A, 4B and 5A of bread wheat carry genes for SS character (bh genes). Among them, the gene on chromosome 2D has the strongest effect on the expression of the SS character. Comparison of disomic and monosomic plants in 2D, 4A, 4B and 5A F2 populations revealed that the bh genes are hemizygous-effective and dosage-independent. The F1 monosomic analysis showed that the bh genes of Yupi Branching are recessive.

Chromosomal Location of Genes for Resistance to Karnal Bunt in Wheat

Karnal bunt (Tilletia indica Mitra) infestation of wheat (Triticum aestivum L.) kernels reduces grain quality. Deployment of genetic resistance would be preferable to chemical applications for control of the disease. Inoculation studies were carried out in a wheat mapping population with the aim of locating genes for resistance. Recombinant inbred (RI) lines from a cross between a resistant synthetic wheat (Triticum turgidum ‘Altar 84’ × T. tauschii) and the susceptible common wheat cultivar ‘Opata 85’ were inoculated with Karnal bunt sporidial suspension and evaluated for symptom development in the field for three seasons and in the greenhouse. Based on restriction fragment length polymorphism (RFLP) analyses, regions on chromosome arms 3BS and SAL carrying marker alleles from the Altar durum parent were consistently associated with reduced kernel disease. Main marker effects accounted for up to 32% of disease variation in the field but only 15% in the greenhouse, where the level of disease was higher, suggesting an environmental component of resistance. The tagging of these Karnal bunt partial‐resistance genes in tetraploid and hexaploid backgrounds may facilitate the accumulation of resistance via marker‐assisted transfer to susceptible durum and common wheat cultivars. This practice should reduce laborious disease screening requirements.

Coding sequence, exon–intron structure and chromosomal localization of murine TNF-stimulated gene 6 that is specifically expressed by expanding cumulus cell–oocyte complexes

Tumor necrosis factor stimulated gene-6 (TSG-6) has been previously shown to be induced in vitro in several cell types by proinflammatory cytokines, and in vivo in pathological conditions such as rheumatoid arthritis. In this study, we report the complete coding sequence for the mouse TSG-6 protein, and the exon–intron structure and the chromosomal localization of the gene. We have identified a 1605 nt cDNA sequence from mouse cumulus cell–oocyte complexes (COCs) induced to expand in vivo. The sequence contains an open reading frame of 825 nt that codes for the 275 amino acid TSG-6 protein. The gene contains six exons separated by 1.1–5.8 kb introns and has been localized to the murine chromosome 2 by linkage analysis. Comparative reverse transcription–polymerase chain reaction studies have revealed that TSG-6 mRNA is specifically expressed after COC expansion induced in vivo, identifying the first non-pathological process in which TSG-6 may play an important role. Since TSG-6 binds to hyaluronan and interacts with inter- α-trypsin inhibitor (I αI), molecules that are essential for matrix formation by COCs, this protein may have a structural role in the matrix or may enhance the antiproteolytic effect of I αI to protect the matrix from degradation.

Chromosomal location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L. em. Thell.) 4. Gene Pm 24 in Chinese landrace Chiyacao

Chinese wheat landrace Chiyacao exhibited a response pattern different from that of the cultivars/lines possessing documented Pm genes after inoculation with 106 isolates of Erysiphe graminis f. sp. tritici. To characterize this resistance and to determine the chromosomal location of the gene or genes present, we crossed the landrace to susceptible cultivar ‘Chinese Spring’ and also to a set of 21 ‘Chinese Spring’ monosomic lines. Monosomic F1 plants were allowed to self-pollinate and to produce F2 seeds. Seedlings of F2 plants and their parents were inoculated with isolates nos. 5 and 12 of Erysiphe graminis f. sp. tritici. The results revealed that one major dominant gene is located on chromosome 6D of Chinese common wheat landrace Chiyacao. The new gene is designated Pm 24.

Contribution of zebrafish-mouse cell hybrids to the mapping of the zebrafish genome

The zebrafish, Danio rerio, is becoming an increasingly popular model for the study of vertebrate development. Indeed, the biology of the fish offers great advantages for such studies. The life cycle of the zebrafish is relatively short (2-3 months) and the embryos develop outside the mother, facilitating the visualization of any mutated phenotype. At present, more than 1000 embryonic mutations have been reported. However, until recently, there was no physical or genetic map for this organism. In an effort to generate such a map, we have produced and characterized a panel of zebrafish-mouse cell hybrids. We have used whole-cell fusion to transfer zebrafish chromosomes from two different zebrafish cell lines into mouse recipient cells, thus generating more than 100 hybrids. Using fluorescence in situ hybridization and polymerase chain reaction analysis, we have determined the zebrafish chromosome composition of these hybrids. Here we report that elements from the 25 linkage groups of the zebrafish genome are present in our hybrids. These hybrids could identify the chromosomal location of genes affected in zebrafish mutants.

Varietal differences and chromosome locations of multiple isoforms of starch branching enzyme in wheat endosperm

Starch branching enzyme isolated from wheat endosperm was fractionated into two distinct isoforms, BE I and BE II, using anion-exchange column chromatography on Q-Sepharose Fast Flow. Both BE I and BE II were separated precisely into several isoforms using native polyacrylamide electrophoresis coupled with enzyme activity staining, and varietal differences in the major BE I isoforms expressed in the endosperm 21 days after flowering were observed. Chromosome locations of genes controlling the expression of the three BE I isoforms of ‘Chinese Spring’ were determined using aneuploid analysis, which indicated that two isoforms, BE I-1 and BE I-2, are controlled by 1DL and the other isoform, BE I-4, is 7BL. © 1997 Elsevier Science Ltd. All rights reserved

Seed banks and molecular maps: unlocking genetic potential from the wild.

Nearly a century has been spent collecting and preserving genetic diversity in plants. Germplasm banks-living seed collections that serve as repositories of genetic variation-have been established as a source of genes for improving agricultural crops. Genetic linkage maps have made it possible to study the chromosomal locations of genes for improving yield and other complex traits important to agriculture. The tools of genome research may finally unleash the genetic potential of our wild and cultivated germplasm resources for the benefit of society.

Chromosomal location of genes for hydroxamic acid accumulation in Triticum aestivum L. (wheat) using wheat aneuploids and wheat substitution lines

Chromosomal location of genes for hydroxamic acid accumulation in Triticum aestivum L. (wheat) using wheat aneuploids and wheat substitution lines

Chromosomal location of genes for hydroxamic acid accumulation in Triticum aestivum L. (wheat) using wheat aneuploids and wheat substitution lines

Hydroxamic acids are defensive secondary metabolites in wheat, the most abundant aglucones being DIMBOA and DIBOA. The location of genes coding for the accumulation of hydroxamic acids by wheat (Triticum aestivum L.) seedlings was explored comparing the euploid of cultivar Chinese Spring with aneuploids of the same cultivar, and substitution lines of cultivar Chinese Spring with cultivar Cheyenne. Significant differences in DIBOA and DIMBOA concentrations in young seedlings with respect to the euploid (0.08 and 5.9 mmol kg−1 fresh weight, respectively) were found in the following lines: monosomic lines 4A (3.9 and 2.8) and 5B (0.29 and 2.7), substitution line 4A (1.7 and 3.2) and nulli/tetra lines N4AT4B (0.39 and 7.0), N4AT4D (0.20 and 0.48), N5BT5A (0.12 and 0.34) and N5BT5D (0.06 and 0.63). These results suggest the involvement of chromosomes of group 4 and also chromosome 5B in the accumulation of hydroxamic acids in wheat seedlings.

Effects of loci on chromosomes 2 (2H) and 7 (5H) on developmental patterns in barley (Hordeum vulgare L.) under different photoperiod regimes

Heading-date in cereals is the final result of a number of interacting characters that include vernalization requirement, photoperiod sensitivity, and earliness per se. Progress in developing adapted varieties may be achieved by determining the chromosomal locations of genes controlling these characters. Nineteen doubled-haploid (DH) lines from the Dicktoo×Morex mapping population were phenotyped in controlled- environment photoperiod experiments to determine the role of two previously detected QTLs on the developmental patterns of barley. The QTLs are hypothesised to represent the effects of the Ppd and Sh2 loci on chromosomes 2 (2H) and 7 (5H), respectively. Alleles at the Ppd locus were found to be vary in response to photoperiod duration. Vernalization had some effect on alleles at both loci. The presence of early and late- flowering transgressive segregants in this mapping population can be explained by interactions between the Ppd and Sh2 loci. The Ppd and Sh2 loci are hypothesised to be homoeologous with the Ppd and Vrn1 loci of wheat.