Unusual Proximity Research Articles

An ubiquitously expressed gene 3.5 kilobases upstream of the glycerol-3-phosphate dehydrogenase gene in mice.

While studying the organization of the mouse glycerol-phosphate dehydrogenase gene (Gdc-1 on chromosome 15), we identified a novel transcriptional unit located only 3.4 kilobases (kb) upstream of the 5' end of the Gdc-1 gene. This gene has been provisionally named D15Kz1. The unusual proximity of these two genes led us to investigate the pattern of expression and sequence characteristics of the new gene for comparison with those of Gdc-1. D15Kz1 was found to have transcripts of 3.2 and 3.4 kb in length. The 3.4-kb transcript was expressed at low levels in all tissues examined, whereas the 3.2-kb transcript was detected only in the cerebral cortex and the brown fat. D15Kz1 and Gdc-1 are not coordinately regulated, as evidenced by the characteristics of their expression in several tissues and in differentiating 3T3-F442A adipocyte cultures. A cDNA sequence of 3,105 bases isolated from an embryonal carcinoma lambda gt10 cDNA library had a large open reading frame of 461 amino acids at one end followed by 1.6 kb of sequence with multiple stop codons. Algorithms used to search the protein and nucleic acid data bases detected no significant sequence similarity to any other protein or gene. Southern blot analysis of genomic DNA using the D15Kz1 cDNA as a probe indicated that D15Kz1 is a single-copy gene in the mouse genome and that it is conserved in humans, rats, and chickens. This conservation of gene sequences suggests that D15Kz1 encodes a protein with an important cellular function.

An ubiquitously expressed gene 3.5 kilobases upstream of the glycerol-3-phosphate dehydrogenase gene in mice.

While studying the organization of the mouse glycerol-phosphate dehydrogenase gene (Gdc-1 on chromosome 15), we identified a novel transcriptional unit located only 3.4 kilobases (kb) upstream of the 5' end of the Gdc-1 gene. This gene has been provisionally named D15Kz1. The unusual proximity of these two genes led us to investigate the pattern of expression and sequence characteristics of the new gene for comparison with those of Gdc-1. D15Kz1 was found to have transcripts of 3.2 and 3.4 kb in length. The 3.4-kb transcript was expressed at low levels in all tissues examined, whereas the 3.2-kb transcript was detected only in the cerebral cortex and the brown fat. D15Kz1 and Gdc-1 are not coordinately regulated, as evidenced by the characteristics of their expression in several tissues and in differentiating 3T3-F442A adipocyte cultures. A cDNA sequence of 3,105 bases isolated from an embryonal carcinoma lambda gt10 cDNA library had a large open reading frame of 461 amino acids at one end followed by 1.6 kb of sequence with multiple stop codons. Algorithms used to search the protein and nucleic acid data bases detected no significant sequence similarity to any other protein or gene. Southern blot analysis of genomic DNA using the D15Kz1 cDNA as a probe indicated that D15Kz1 is a single-copy gene in the mouse genome and that it is conserved in humans, rats, and chickens. This conservation of gene sequences suggests that D15Kz1 encodes a protein with an important cellular function.

C mu-containing transcripts initiate heterogeneously within the IgH enhancer region and contain a novel 5'-nontranslatable exon.

Transcriptional competence of the immunoglobulin heavy-chain locus (IgH) is established at an early stage of lymphoid cell development, leading to the appearance of RNA components, previously called C mu RNA1 or sterile-mu RNA2, which contain constant-region sequences but lack variable-region sequences. These components are of two types: those which initiate in the D region of alleles that have undergone DJH (diversity-joining region) rearrangement (D mu transcripts) and those which initiate within the JH-C mu intron (hereafter termed I mu transcripts). In pre-B and early B cells, D mu and I mu transcripts are nearly as abundant as the messenger RNA encoding mu heavy chain. The D mu transcripts are spliced into RNAs containing D, JH and C mu sequences, and in some, but not all, cases these RNAs are translated into D mu proteins. To establish whether the I mu transcripts have any translational potential and to elucidate the structure of their promoter region, we have determined their transcription initiation sites and their mode of splicing. As reported here, by using sequence analysis of cloned I mu complementary DNAs, primer extension and S1 nuclease mapping, we have found that these transcripts have remarkable 5' heterogeneity: there are more than five distinct start sites spanning a region of 44 nucleotides that is located downstream of an octanucleotide found in all variable-region promoters. Such imprecise initiation may result from the lack of a well-defined TATAA motif and the unusual proximity of the octanucleotide to the enhancer region. Approximately 700 nucleotides downstream from these initiation sites, a cryptic splice site is used to create a nontranslatable exon ('nontron') which is joined to the C mu 1 domain. The properties of the nontron may be important for the mechanism of allelic exclusion.

Benzyl alcohol poisoning in a premature newborn infant

later stages often result in stillbirth or premature delivery. The most common site of union is thoracopagus (anterior thoracoabdominal fusion) and is found in 75% of cases. Gray and associates established a list of criteria for the antepartum diagnosis of conjoined twins: (1) The heads are at the same level and body plane; (2) the spines are in unusual proximity; (3) the spines are unusually extended; (4) the fetuses do not change position relative to one another after movement or manipulation. We found the fourth criterion to be most important since ultrasound scanning of the patient on several occasions always showed the area of the two chests to be in the same position relative to each fetus whenever fetal movement occurred. The single shared fetal heart also remained in the same position relative to each fetus whenever fetal movement occurred. It is suggested that whenever genetic amniocentesis reveals twins one should carefully ascertain if one or more amniotic sacs are present. This may be confirmed with indigo carmine dye injected into the amniotic cavity at the first puncture site and blue amniotic fluid obtained at a second puncture site. When monoamniotic twins are diagnosed, the fetuses should be carefully studied with ultrasound for the possibility of conjoined twins. The diagnosis of conjoined twins at an early stage of pregnancy allows the option of termination of the pregnancy. This is important because the chance of successful separation of the twins is usually low, especially if only one heart is present. I Many conjoined twins also have malformations not associated with the site of conjoining.

Electron impact studies—LXV: Negative‐ion mass spectrometry of functional groups 2‐aryl‐1,3‐dithianes

AbstractThe negative‐ion mass spectra of 2‐aryl‐1,3‐dithianes contain pronounced molecular anions together with fragment ions which are produced by both simple and complex cleavage reactions. These spectra contain further examples of specific hydrogen scrambling processes in negative ions. Nitroaryldithianes give intense negative‐ion spectra, and that of the o‐nitro derivative exhibits an unusual proximity effect. The fragmentation patterns have been examined using both 2H and 13C labelling and the metastable defocusing technique.