29 research outputs found
The cooling of atomic and molecular gas in DR21
We present an overview of a high-mass star formation region through the major
(sub-)mm, and far-infrared cooling lines to gain insight into the physical
conditions and the energy budget of the molecular cloud. We used the KOSMA 3m
telescope to map the core () of the Galactic star forming region
DR 21/DR 21 (OH) in the Cygnus X region in the two fine structure lines of
atomic carbon CI and four mid- transitions of CO and CO, and CS
J=7\TO6. These observations have been combined with FCRAO J=1\TO0
observations of CO and CO. Five positions, including DR21, DR21
(OH), and DR21 FIR1, were observed with the ISO/LWS grating spectrometer in the
\OI 63 and 145 m lines, the \CII 158 m line, and four high- CO
lines. We discuss the intensities and line ratios at these positions and apply
Local Thermal Equilibrium (LTE) and non-LTE analysis methods in order to derive
physical parameters such as masses, densities and temperatures. The CO line
emission has been modeled up to J=20. From non-LTE modeling of the low- to
high- CO lines we identify two gas components, a cold one at temperatures of
T_\RM{kin}\sim 30-40 K, and one with T_\RM{kin}\sim 80-150 K at a local
clump density of about n(H) cm. While the cold
quiescent component is massive containing typically more than 94 % of the mass,
the warm, dense, and turbulent gas is dominated by mid- and high- CO line
emission and its large line widths. The medium must be clumpy with a
volume-filling of a few percent. The CO lines are found to be important for the
cooling of the cold molecular gas, e.g. at DR21 (OH). Near the outflow of the
UV-heated source DR21, the gas cooling is dominated by line emission of atomic
oxygen and of CO
Expression of three rare fragile sites: chromosomal truncation, amplification of distal segment and telomeric renewal
Fluorescence in situ hybridization with a telomeric probe was used to monitor telomeric renewal following breakage induced by the rare fragile sites FRA10A, FRA12A and FRA16B. Interstitial telomere-like sequences were detected only at the break sites of FRA10A
Prenatal diagnosis of an extranumerary i(22p) with normal phenotype
A DA-Dapi and AgNOR-negative extranumerary chromosome was identified prenatally in a male fetus and also found in his normal father. Fluorescence in situ hybridization using repetitive DNA probes showed that the minute marker was positive at both ends for beta-satellite sequences, while its centromere was recognized by a 22 alphoid probe. It is concluded that the non-mosaic familial marker represents a 22p isochromosome
Different phenotypes in two cases of an apparently identical familial (Yq;13p) translocation
A chromosome 13 with extra material on the short arm was observed in a 17-year-old boy showing defects in skeletal growth, an altered hormone profile and asthenoteratozoospermia, and in a 46 XX fetus subjected to prenatal diagnosis. The abnormal chromosome 13 had been transmitted from phenotypically normal parents who were the mother (case 1) and the father (case 2). The extra material on the abnormal chromosome 13 was brightly fluorescent after Q-banding, and positive in C-banding (CBG) and distamycin A-Dapi (DA-Dapi) banding. Staining of the nucleolus organizer region indicated its retention. In-situ hybridization of a Yq-specific repetitive DNA probe to chromosomal spreads from both cases demonstrated that the der(13) chromosome contains sequences of the Yq heterochromatic region. However, the apparently identical unbalanced (Y;13) translocation may either interfere (case 1) or not (father of case 2) with meiotic or postmeiotic sperm cell development
Characterization of the genomic structure of the human neuronal nicotinic acetylcholine receptor CHRNA5/A3/B4 gene cluster and identification of novel intragenic polymorphisms
Genes coding for the alpha5, alpha3, and beta4 subunits (CHRNA5, CHRNA3, and CHRNB4) of the neuronal nicotinic acetylcholine receptors (nAChRs) are clustered on chromosome 15q24. Linkage of this chromosomal region to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), an idiopathic partial epilepsy, was reported in one family. Moreover, mutations in other neuronal nAChR subunit genes coding for the alpha4 (CHRNA4) and the beta2 (CHRNB2) subunits were associated with ADNFLE. Apart from the exon-intron structure of CHRNA3, the genomic organization of this gene cluster was unknown, making comprehensive mutational analyses impossible. The genomic structure of CHRNA5 and CHRNB4 is here reported. Moreover, two hitherto unknown introns were identified within the 3' untranslated region of CHRNA3, causing a partial tail-to-tail overlap with CHRNA5. Four novel intragenic polymorphisms were identified and characterized in the cluster
Characterization of a non-recurrent familial translocation t(7;9)(q11.23;p24.3) points to a recurrent involvement of the Williams-Beuren syndrome region in chromosomal rearrangements
Recurrent and non-recurrent chromosomal
rearrangements seem to reflect susceptibility to DNA
rearrangements due to the presence of recombinogenic
motifs in at least one partner chromosomal region.
While specific genomic motifs such as AT-rich repeats,
fragile sites and Alu repeats are often found in recurrent
translocations, the molecular mechanisms underlying
non-recurrent chromosomal rearrangements remain
largely unknown. Here, we map the breakpoint region of
a non-recurrent translocation, t(7;9)(q11.23;p24.3),
present in a healthy woman who inherited the apparently
balanced translocation from her mother and
transmitted the same rearrangement to two sons
\u2014respectively healthy and aborted. Characterisation by
a two-step FISH analysis, first with BAC clones and
then with small locus-specific probes, restricted the
breakpoint intervals to 8\u201310 kb. Both regions contained
specific Alu sequences, which, together with the flanking
low copy repeat block Ac in 7q11.23, might stimulate the
translocation. We noted that, although the translocation
is non-recurrent, 7q11.23 is recurrently involved in different
chromosomal rearrangements, supporting the
hypothesis that the 7q11.23 genomic structure is prone
to recombination event
A complete duplication of X chromosome resulting in a tricentric isochromosome originated by centromere repositioning
Neocentromeres are rare and considered chromosomal aberrations, because a non-centromeric region evolves in an active centromere by mutation. The literature reported several structural anomalies of X chromosome and they influence the female reproductive capacity or are associated to Turner syndrome in the presence of monosomy X cell line