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21.
George L. Gabor Miklos Marion J. Healy P. Pain A. J. Howells Robyn J. Russell 《Chromosoma》1984,89(3):218-227
A recombinant Charon 4 bacteriophage has been isolated on the basis of RNAs which are enriched in the head of the adult Drosophila melanogaster and hence are likely to be of neural origin. The cloned insert maps to the near vicinity of the uncoordinated locus in polytene chromosome band 19E8. This band is within the transition zone between the euchromatic and heterochromatic regions of the X chromosome, a region which has been well characterized cytogenetically. The insert contains both repetitious and low copy number sequences, some of which vary extensively in both frequency and restriction fragment size between different laboratory strains. One particular family of moderately repeated sequences occurs predominantly in divisions 19 and 20 of the X chromosome and perhaps the distally located X heterochromatin. The molecular landscape surrounding the initial entry point contains many repeated sequences and is thus unlike those observed in most published chromosomal walks. The possible significance of the presence of repeated sequence families in the distinct properties of this region are discussed. 相似文献
22.
When differences are found between related species of organisms, it is often assumed that the differences themselves are causal factors either in speciation itself or in processes related to speciation. Two recent proposals on the functions of satellite DNA (Hatch et al., 1976 and Fry and Salser, 1977) are that (a) large amounts of satellite DNA are important in facilitating chromosome rearrangements and hence cytogenetic evolution, and (b) satellite DNA differences between homologous chromosomes lead to pairing difficulties and are important in generating infertility barriers and hence speciation. If these proposals were to have some generality, one could expect organisms with very low amounts of highly repeated DNA to exhibit few chromosome rearrangements and to be evolutionarily conservative in a cyto-genetic sense. — We have chosen two very closely related species of rat which are phenotypically almost indistinguishable and which have undergone massive genome reorganization. They differ by 11 major centric rearrangements (2n=32, 2n=50). We have characterised their genomes by restriction endonuclease digestions, thermal denaturations, analytical ultracentrifugations and reassociation techniques, and have found that they have virtually no highly repeated DNA. Thus the 11 major chromosomal rearrangements have been fixed in present day genomes with hardly any highly repeated DNA, centric or otherwise. — It appears therefore that a large amount of highly repeated DNA is not obligatory for the formation and fixation of chromosome rearrangements. In addition, the existing literature reveals that one can find almost any situation at all, from species groups with high amounts of satellite DNA and no gross chromosomal rearrangements, to ones such as those described here, with tiny amounts of highly repeated DNA and massive chromosomal reorganisation. Since direct experimental data indicates that satellite DNA differences per se between homologous chromosomes do not cause infertility, speculations concerning modes of speciation based on satellite DNA differences between otherwise homologous chromosomes would appear to be ill founded. 相似文献
23.
Do Quang Binh László E. Heszky Gabor Gyulai Anikó Csillag 《Plant Cell, Tissue and Organ Culture》1992,29(2):75-82
Cells of a 2-year-old suspension culture of rice (Oryza sativa L.), grown under 1.5% NaCl stress for 3 months, gave rise to plants through embryogenesis in different saline conditions. The high regeneration potential (59.6%) on salt-free medium decreased rapidly with increasing concentration of salt in the regeneration medium. At 1.25% NaCl, healthy shoots were developed in 14.9% of the cultures. Under 1.5% salt stress, embryo formation and embryo germination (6.1%) was observed but further development into plants was inhibited. Cells not pretreated with salt produced plants at a low frequency (2.6–4.2%) both in salt-free and low saline condition (0.75–1% NaCl). Cells pretreated for 3 months with 0.75% salt did not give rise to plants on all tested media. Plants regenerated from the salt-stressed cultures were transferred to soil and grew to maturity in a greenhouse.Abbreviations BA
6-benzyladenine
- CH
casein hydrolysate
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
1-naphthaleneacetic acid 相似文献
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Congenital nephrotic syndrome of the Finnish type maps to the long arm of chromosome 19. 总被引:12,自引:8,他引:4
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M. Kestil M. Mnnikk C. Holmberg G. Gyapay J. Weissenbach E. R. Savolainen L. Peltonen K. Tryggvason 《American journal of human genetics》1994,54(5):757-764
Congenital nephrotic syndrome of the Finnish type (CNF) is an autosomal recessive disease that is characterized by massive proteinuria and nephrotic syndrome at birth. CNF represents a unique, apparently specific dysfunction of the renal basement membranes, and the estimated incidence of CNF in the isolated population of Finland is 1 in 8,000 newborns. The basic defect is unknown, and no specific biochemical defect or chromosomal aberrations have been described. Here we report the assignment of the CNF locus to 19q12-q13.1 on the basis of linkage analyses in 17 Finnish families. Multipoint analyses and observed recombination events place the CNF locus between multiallelic markers D19S416 and D19S224, and the significant linkage disequilibrium observed suggests that the CNF gene lies in the immediate vicinity of the markers D19S224 and D19S220. 相似文献
27.
Anthony Johns K. Rewers-Felkins P. Devesly Gabor M. Rubanyi Lynne H. Parker-Botelho 《Neurochemistry international》1991,18(4):575-580
Specific receptor-induced signal transduction mechanisms for the endothelin-2 isoform (ET-2), a potent vasoconstrictor of vascular smooth muscle, were examined in Swiss 3T3 cells. Half-maximal binding (EC50) and maximal, saturable binding (Bmax) were estimated from Scatchard analyses and were found to be 24.2 ± 3.3 pM and 56500 ± 1700 sites/cells, respectively. A saturating concentration of ET-2 (100 nM) increased intracellular free calcium (measured by Fura-2 fluorescence) from a resting level of 100 nM to a peak level of 600–800 nM. The initial increase in intracellular free calcium was transitory and was followed by a smaller maintained elevation (250 nM). In the absence of extracellular calcium, ET-2 induced a transitory response equal in size to the peak in the presence of extracellular calcium, but the maintained response was absent. ET-2 increased intracellular free calcium in a concentration-dependent manner with an EC50 of 1 nM. In calcium free solution (2 mM EGTA), ET-2 increased the efflux of 45Ca from cells loaded to isotopic equilibrium (3 h) with 45Ca. The intracellular second messenger, IP3, also increased the calcium efflux from saponin permeabilized 3T3 cells loaded with 45Ca (pCa 6) in the presence of MgATP. In the presence of extracellular calcium, ET-2 significantly increased calcium uptake into 3T3 cells by 92 ± 36.6 pmoles/million cells/2 min (n = 8). It is suggested that ET-2 binds to specific, high affinity receptors in 3T3 cells and that this receptor interaction increases the intracellular free calcium by IP3-induced mobilization of calcium from cellular stores and by increasing influx of extracellular calcium. 相似文献
28.
Abdelwahab ElHusseiny M. M. Bovari-Biri Judit Smuk Gabor Fillinger Janos McPhail Donald Krymskaya Vera P. Pongracz Judit E. 《Apoptosis : an international journal on programmed cell death》2021,26(5-6):253-260
Apoptosis - Tuberous sclerosis, angiomyolipoma and lymphangioleiomyomatosis are a group of diseases characterized by mutation in tuberous sclerosis genes (TSC 1-2). TSC mutation leads to continuous... 相似文献
29.
Gabor J. Barton Malcolm B. Hawken Gill Holmes Michael H. Schwartz 《Computer methods in biomechanics and biomedical engineering》2013,16(1):57-63
The ability of the Movement Deviation Profile (MDP) and Gait Deviation Index (GDI) to detect gait changes was compared in a child with cerebral palsy who underwent game training. Conventional gait analysis showed that sagittal plane angles became mirrored about normality after training. Despite considerable gait changes, the GDI showed minimal change, while the MDP detected a difference equal to a shift between 10-9 on the Functional Assessment Questionnaire scale. Responses of the GDI and MDP were examined during a synthetic transition of the patient's curves from before intervention to a state mirrored about normality. The GDI showed a symmetric response on the two opposite sides of normality but the neural network based MDP gave an asymmetric response reflecting faithfully the unequal biomechanical consequences of joint angle changes. In conclusion, the MDP can detect altered gait even if the changes are missed by the GDI. 相似文献
30.
Swee Tin Aw Michael John Todd Nadine Lehnen Grace Elizabeth Aw Konrad Peter Weber Thomas Eggert Gabor Michael Halmagyi 《PloS one》2013,8(12)