Chromosomes variations

Heywood, J. S. and Levin, D. A. 1984. Allozyme variation in Gaillardia pulchella and G. amblyodon (Compositae) Relation to morphological and chromosomal variation and to geographicalisola-tion. Syst. Bot. 9 448-457. 

Hammer MF, Karapet T, Rasanayagam A, Wood ET, Althiede TK, Jenkins T et al. Out of Africa and back again Nested cladistic analysis of human Y chromosome variation. Mol Biol Evol 1998 15 427-441. 

Goswami HK, Chandorkar M, Bhattacharya K, et al Search for chromosomal variations among gas-exposed persons in Bhopal. Hum 84(2) 172-176, 1990... 

Schleper, C., DeLong, E. P., et al. (1998). Genomic analysis reveals chromosomal variation in natural populations of the uncultured psychrophilic Archaeon Cenarchaeum symbiosum. J. Bacterial. 180, 5003-5009. 

D9. De Carli, L., Maio, J. J., and Nuzzo, F., Alkaline phosphatase activity and chromosome variations in human cells in culture. J. Natl. Cancer Inst. 31, 1501-1509 (1963). 

Hammer, Michael, A B Spurdle, T Karafet, M R Bonner, E T Wood, A NoveUetto, P Malaspina, R J Michell, S Horai, T Jenkins, S L Zegura The geographic distribution of human Y chromosome variation. Genetics 1997, Mar 145(3) 787-805... 

Hammer, Michael, T Karafet, A Rasanayagam, E T Wood, T K Altheide, T Jenkins, R C Griffiths, A R Templeton S L Zegura Out of Africa and back again nested cladistic analysis of human Y chromosome variation Mol Biol Evol 1998 Apr, 15(4) 427-441... 

Bayliss MW (1980) Chromosomal variations in plant tissues in culture. In Vasil IK (ed) Perspectives in plant cell and tissue culture. Supplement 11 A, International review of cytology. Academic New York, pp 113-144 Behre K (1929) Physiologische und zytologische Untersuchungen iiber Drosera. Planta (Berl) 7 208-306... 

These findings were unexpected because previous studies had demonstrated that the y2 subunit is required for potentiation of GABAa receptor function by low concentrations of ethanol [2]. The y2 subunit gene is located within a definitely mapped quantitative trait locus (QTL) for acute alcohol withdrawal on mouse chromosome 11 [1]. Allelic variation was genetically... 

Figure 1. Immunofluorescent labeling of dystrophin in the Xp21 muscular dystrophies. In normal muscle, clear uniform labeling is present at the membrane of each muscle fiber. In Becker muscular dystrophy (BMD), there is inter- and intrafiber variation in labeling intensity. In Duchenne muscular dystrophy (DMD), most fibers are devoid of labeling (note, however, that in most biopsies occasional fibers exhibit weak labeling). In the biopsy from a manifesting carrier, some fibers show normal labeling and others are negative. In the former, the normal X-chromosome is active while in the latter the abnormal X-chromosome is active.

Short-chain acyl-CoA dehydrogenase (SCAD) deficiency has been recorded in only a few patients and these show wide variation in clinical presentation. The defect has been seen in infants with a syndrome of psychomotor retardation and failure to thrive. These infants showed abnormal organic aciduria, and drastically decreased SCAD activity was demonstrable in cultured fibroblasts. Muscle symptoms were only part of a wider syndrome in all infants and children so far reported to have SCAD deficiency, but were the sole presenting feature in two adult patients, in whom lipid storage was demonstrable in skeletal muscle. The gene encoding for human SCAD has been mapped to chromosome 12. 

A third class of sequence elements can either increase or decrease the rate of transcription initiation of eukaryotic genes. These elements are called either enhancers or repressors (or silencers), depending on which effect they have. They have been found in a variety of locations both upstream and downstream of the transcription start site and even within the transcribed portions of some genes. In contrast to proximal and upstream promoter elements, enhancers and silencers can exert their effects when located hundreds or even thousands of bases away from transcription units located on the same chromosome. Surprisingly, enhancers and silencers can function in an orientation-independent fashion. Literally hundreds of these elements have been described. In some cases, the sequence requirements for binding are rigidly constrained in others, considerable sequence variation is... 

SNP Single nucleotide polymorphism. Refers to the fact that single nucleotide genetic variation in genome sequence exists at discrete loci throughout the chromosomes. Measurement of allelic SNP differences is useful for gene mapping studies. 

There are wide variations in features of individual chromosomes (eg, in gene number per Mb, SNP density, GC content, numbers of transposable elements and CpG islands, recombination rate). 

Tishler, P. V. Lamborot-Manzur, M. and Atkins, L. "Polymorphism of the Human Y Chromosome Fluorescence Microscopic Studies on the Sites of Morphological Variation". 

It is clear that both intact cell MALDI-TOF and PFGE have their limitations. PFGE analyses probes the chromosomal DNA of microorganisms for variations in the locations of specific restriction enzyme cleavage sites, while MALDI-TOF mass spectrometry of intact cells primarily examines abundant proteins such as ribosomal proteins35 and those associated with or near bacterial cell walls.58 In order for MALDI-TOF to detect a variation, a mutation must lead to noticeable changes in the expression of cell wall—associated... 

Allele Variations in the recipe between individuals just as there are slightly different recipes for the same dish, there are slightly different genes for the same protein since humans have pairs of each chromosome (one from each parent), for each gene a given individual can have two alleles that are the same or different. 

Rapid sequencing and single nucleotide polymorphisms (SNPs) will play a major role in associating sequence variations with heritable clinical phenotypes of drug or xenobiotic response. SNPs occur approximately once every 300-3,000 base pairs if one compares the genomes of two unrelated individuals [13, 14]. Any two individuals thus differ by approximately 1-10 million base pairs, i.e., in < 1% of the approximately 3.2 billion base pairs of the haploid genome (23 chromosomes). 

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