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PubMed1986

Proenkephalin A gene expression in bovine adrenal chromaffin cells is regulated by changes in electrical activity.

Concentrations of mRNA coding for the opioid peptide precursor proenkephalin A (mRNAENK) were measured in primary cultures of bovine adrenal chromaffin cells maintained in serum-free medium. Using a sensitive solution hybridization assay, an increase in mRNAENK levels from 45 to 300% above control with K+ (10-20 mM), Ba2+ (1 mM) and veratridine (5 microM) was found. The highest increase (300% above control) was obtained with the Na+ channel agonist veratridine. This effect was nearly abolished in the presence of the Na+ channel antagonist tetrodotoxin (TTX) (1 microM). Moreover, TTX partially inhibited the increase in mRNAENK levels caused by K+ (20 mM) depolarization (from 185 to 130% of control), but had no effect on the stimulation by Ba2+ (1 mM). The Ca2+ channel antagonists D600 (50 microM) verapamil (50 microM) and Co2+ (1 mM) inhibited the responses to either K+, Ba2+ or veratridine, whereas the Ca2+ channel agonist Bay K 8644 (0.1 microM) potentiated the effect of 20 mM K+ from 185 to 230% of control. The K+-induced increase in the mRNAENK levels was associated with an increase of immunoreactive proenkephalin A-derived peptides in both tissue and medium, indicating an enhanced production of opioid peptides. These results suggest that membrane depolarization may play an important role in the regulation of proenkephalin A gene expression in bovine adrenal chromaffin cells. It may represent a mode by which substances acting directly on Na+ or Ca2+ channels may modulate the regulation of proenkephalin A mRNA biosynthesis and opioid peptide production.

Adrenal Medulla↗
PubMedDate not supplied

Genetic instability in human mismatch repair deficient cancers.

Cancers showing microsatellite instability (MSI-H) are frequent tumors characterized by inactivating alterations of mismatch repair (MMR) genes that lead to an incapacity to recognize and repair errors that occur during DNA replication. These cancers can be inherited as in the human non-polyposis colorectal cancer syndrome, or can occur sporadically in 10-15% of colorectal, gastric and endometrial cancers. MSI-H tumors have different clinicopathological features compared to cancers without this phenotype, termed MSS, and the repertoire of genetic events involved in tumoral progression of both phenotypes is thought to be different. In MSI-H tumors, most of the genetic changes occur at both non-coding and coding microsatellites that are particularly prone to errors during replication due to their repetitive sequence. This mechanism appears to be the main "genetic pathway" by which functional changes with putative oncogenic effects are accumulated in these tumors.

Base Pair Mismatch↗
PubMed1990

Regulation by a protein-free carbohydrate-rich diet of rat pancreatic mRNAs encoding trypsin and elastase isoenzymes.

The levels of mRNAs coding for trypsin and elastase isoenzymic forms were determined in the pancreatic tissue of rats fed a high-carbohydrate protein-free diet for a 0-5-day period. No change in the amounts of mRNAs coding for the two isoelastases was observed, although previous results showed that the biosynthesis of anionic elastase was markedly increased, whereas the biosynthesis of cationic elastase decreased, suggesting the existence of a translational-control mechanism in response to nutritional substrates. In contrast, the levels of mRNAs specific for the three isotrypsins were significantly enhanced, possibly as a result of transcriptional regulation and/or a change in messenger stability. In combination with earlier observations of an overall decrease in cationic trypsin biosynthesis during the same nutritional manipulation, these results suggest that formation of this enzyme is also subject to translational control.

Animals↗
PubMed1989

Cloning and sequencing of the gamma-subunit of retinal cyclic-GMP phosphodiesterase from rd mouse.

Molecular cloning, sequencing and Northern blot analysis have been performed on the gamma-subunit of cyclic-GMP phosphodiesterase (cGMP-PDE gamma) from the retina of mice affected with the rd mutation. The full length cDNA has a total of 926 bp which include 261 bp of coding region, 121 bp of 5'-untranslated and 544 bp of 3'-untranslated regions. The latter contains a poly A tail of 50 bp. The coding region has only one base changed from the normal mouse cGMP-PDE gamma cDNA, a C replaced by an A at position 105 (Tuteja and Farber, 1988), and 91% homology with the coding region of the bovine retinal enzyme (Ovchinnikov et al., 1986). The mRNA of cGMP-PDE gamma is 900 bp long in both normal and rd mouse retinas and codes for a protein containing 87 amino acids. The deduced amino acid sequence of cGMP-PDE gamma from rd retina has 100% homology with that of the enzyme from normal mouse retina and 97.7% homology with that of the bovine cGMP-PDE gamma suggesting that if this subunit of cGMP-PDE is properly transcribed and translated, it is not defective in the degenerative rd mouse retina.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1985

Coding of amplitude-modulated tones in the central auditory system of catfish.

In the catfish central acoustic system information is coded by two subsets of units. Type I units show little or no adaptation, type II units adapt rapidly, and some units are transitional, showing moderate adaptation. The two groups of units also respond differently when exposed to sinusoidal amplitude modulation of the signal's carrier frequency. The tonic, less readily adapting type I units code over an intensity range of about 30 dB, are fairly insensitive to intensity changes, and follow stimulus envelopes of 60 Hz and less. They apparently discharge in response to the actual intensity of the signal rather than in response to something in its temporal pattern. The onset-sensitive, fast-adapting type II units on the other hand are restricted to an intensity range of only 10 dB, show greater sensitivity to intensity changes, and are capable of following the temporal pattern of amplitude-modulated stimuli exceeding 100 Hz. These units appear to code the temporal changes in the stimulus intensity irrespective of the absolute intensity of the signal.

Adaptation, Physiological↗
PubMed1989

The codon CUG is read as serine in an asporogenic yeast Candida cylindracea.

Deviations from the universal genetic code have been reported for several microorganisms. Termination codons are used for coding some amino acids in Paramecium, Mycoplasma or Tetrahymena, and in Escherichia coli, the UGA termination codon is used to code for selenocysteine. In mitochondria, the changes of sense codons to termination codons or to codons encoding other amino acids have also been reported. Here we report another example of divergence from the universal code, this time in a non-spore-forming yeast Candida cylindracea, in which the universal codon for leucine, CUG, is used to code for serine. This conclusion is based on the observations that: (1) the amino-acid composition and the partial amino-acid sequences of an extracellular lipase from this yeast agreed with those deduced from the complementary DNA if CUG was assumed to specify serine; and (2) serine, but not leucine, was incorporated into a polypeptide in a cell-free translation system from this yeast in the presence of a synthetic CUG oligomer.

Amino Acid Sequence↗
PubMed2005

Neural correlates of switching from auditory to speech perception.

Many people exposed to sinewave analogues of speech first report hearing them as electronic glissando and, later, when they switch into a 'speech mode', hearing them as syllables. This perceptual switch modifies their discrimination abilities, enhancing perception of differences that cross phonemic boundaries while diminishing perception of differences within phonemic categories. Using high-density evoked potentials and fMRI in a discrimination paradigm, we studied the changes in brain activity that are related to this change in perception. With ERPs, we observed that phonemic coding is faster than acoustic coding: The electrophysiological mismatch response (MMR) occurred earlier for a phonemic change than for an equivalent acoustic change. The MMR topography was also more asymmetric for a phonemic change than for an acoustic change. In fMRI, activations were also significantly asymmetric, favoring the left hemisphere in both perception modes. Furthermore, switching to the speech mode significantly enhanced activation in the posterior parts of the left superior gyrus and sulcus relative to the non-speech mode. When responses to a change of stimulus were studied, a cluster of voxels in the supramarginal gyrus was activated significantly more by a phonemic change than by an acoustic change. These results demonstrate that phoneme perception in adults relies on a specific and highly efficient left-hemispheric network, which can be activated in top-down fashion when processing ambiguous speech/non-speech stimuli.

Adult↗
PubMed1993

Variation and genetic control of surface antigen expression in mycoplasmas: the Vlp system of Mycoplasma hyorhinis.

Surface antigenic diversity in the swine pathogen Mycoplasma hyorhinis is generated by random combinatorial expression and high-frequency phase variation of multiple, size-variant membrane surface lipoproteins (Vlps) which represent the major coat proteins of this wall-less procaryote. The distinctive structural basis for Vlp variation was revealed in a family of several related but divergent vlp genes. These occur in one cluster as single chromosomal copies, each encoding a conserved domain for membrane insertion and lipoprotein processing, and a divergent external domain that changes size by deletion or insertion of repetitive intragenic coding sequences while retaining a distinctive charge motif. Lack of detectable changes in restriction fragment patterns or DNA sequence of vlp structural genes during phase transitions between ON and OFF expression states ruled out long range genomic rearrangements and frameshift mutations as a means of controlling Vlp phase variation. However, highly homologous vlp promoter regions contain a homopolymeric tract of contiguous adenine residues [poly(A)] upstream of the transcriptional start site which is subject to frequent mutations altering its length. These mutations are the only sequence changes detected during phase transitions, and are highly correlated with the expression state of each vlp gene. This suggests a mechanism of transcriptional control regulating Vlp phase variation by critical changes within the poly(A) region affecting the spacing between the -10 and -35 hexamers or a putative regulator binding site. The multiple levels of structural and antigenic diversity embodied in the vlp gene family may provide essential adaptive capabilities for this wall-less microbial pathogen.

Animals↗
PubMed2006

Analysis of the Leishmania donovani transcriptome reveals an ordered progression of transient and permanent changes in gene expression during differentiation.

Leishmania donovani is an intracellular protozoan parasite that causes kala-azar in humans. During infection the extracellular insect forms (promastigotes) undergo rapid differentiation to intracellular amastigotes that proliferates in phagolysosomes of mammalian macrophages. We used microarray-based expression profiling to investigate the time-course of changes in RNA abundance during promastigote-to-amastigote differentiation in a host-free system that mimics this process. These studies revealed that several hundred genes underwent an ordered progression of transient or permanent up- and down-regulation during differentiation. Genes that were permanently up-regulated in amastigotes were enriched for transporters and surface proteins, but under-represented in genes involved in protein and other metabolism. Most of these changes occurred late in the differentiation process, when morphological differentiation was essentially complete. Down-regulated genes were over-represented in those involved in cell motility, growth and/or maintenance, and these changes generally occurred earlier in the process. Genes that were transiently up- or down-regulated during differentiation included those encoding heat shock proteins, ubiquitin hydrolases, RNA binding proteins, protein kinases, a protein phosphatase, and a histone deacetylase. These results suggest that changes in mRNA abundance may be important in signal transduction, as well as protein and mRNA turnover, during differentiation. In addition to these mRNA changes, other transcripts including one or more rRNAs and snoRNAs, and non-coding RNAs from several telomeres, also showed substantial changes in abundance during the differentiation process. This paper provides the first genome-scale quantitative analysis of gene expression during the transition from promastigotes to amastigotes and demonstrates the utility of the host-free differentiation system.

Animals↗
PubMed1983

The F1F0-ATPase of Escherichia coli. Substitution of proline by leucine at position 64 in the c-subunit causes loss of oxidative phosphorylation.

The uncE410 allele differs from the normal uncE gene in that C leads to T base changes occur at nucleotides 190 and 191, resulting in proline at position 64 in the c-subunit of the F1F0-ATPase being replaced by leucine. Two partial-revertant strains were isolated in which alanine-20 of the c-subunit was replaced by proline, owing to a G leads to C base change at nucleotide 58. These c-subunits, coded for by the uncE501 and uncE502 alleles, therefore contained two amino acid changes, namely proline-64 leads to leucine, and alanine-20 leads to proline. Membranes prepared from the partial-revertant strains lacked ATP-dependent atebrin-fluorescence-quenching activity but were able to carry out oxidative phosphorylation. The ATPase activity of the F1-ATPase was inhibited when bound to membranes from strains carrying the uncE410, uncE501 and uncE502 alleles. It is concluded that a bend in the helix axis in one of the arms of the c-subunit hairpin structure is required for integration of the c-subunit into a functional F1F0-ATPase.

Adenosine Triphosphatases↗
PubMed2005

Genomic characterization of KIR2DL4 in families and unrelated individuals reveals extensive diversity in exon and intron sequences including a common frameshift variation occurring in several alleles.

The KIR2DL4 gene including a portion of exon 1 through exon 9 was sequenced from two families and eight cell lines from the International Histocompatibility Workshop (IHWS). Two known alleles and eight variants were detected. Overall, there were five synonymous and three non-synonymous changes when the variants were compared to the coding sequences of the most closely related known alleles plus a common frameshift change in five of the variant alleles. Alignment of the new variants with all known alleles showed that the regions encoding the extracellular region and the cytoplasmic tail were the most polymorphic. Two non-synonymous changes, P146H and L161V, occurred in an extracellular immunoglobulin-like domain. Five of the eight variants had a single adenine deletion in the exon encoding the transmembrane region, potentially resulting in a truncated protein lacking the cytoplasmic tail. The distribution of the deletion variant among many KIR2DL4 alleles may explain the high frequency of this variation in the population. Four of the eight consanguineous IHWS cell lines were found to be heterozygous for KIR2DL4 carrying two alleles that differed from one another by a few nucleotide substitutions. Analysis of intron sequences in the families revealed the nature and distribution of interspersed repeat elements which comprise 46% of the KIR2DL4 nucleotide sequence and consist of 12 elements including six SINEs (13.73% of the total length), one LINE (12.41%), and five LTR elements (19.51%). The results revealed the presence of extensive diversity in the KIR2DL4 gene. This is the first extensive report providing both exon and intron data in related individuals.

Alleles↗
PubMed2002

Coding and billing for gastrointestinal endoscopy.

The complexities associated with the coding, billing, and reimbursement process seem to increase daily. Keeping abreast of the changes in this environment is, to say the least, a challenge. To succeed in today's billing environment the gastroenterologist should surround his or her practice with staff, resources, and education. Experienced skilled staff, preferably a certified professional coder should be employed. Certified coders bring advanced coding skills to ones practice, which allows increased proficiency with the coding and billing process. Provide the necessary resources for staff. Current coding material is crucial to the financial success of the practice. CPT-4, ICD-9, and Correct Coding Guide are the bare basics of the resource material available to staff. Maintaining a library of resource material (i.e., Medicare bulletins, managed care newsletters, and so forth) aids the staff with the necessary tools to carry out their duties. In addition, specific gastroenterology coding subscriptions are available to assist in staying ahead of the ever-changing billing and coding environment. Continuing education in the billing and coding process for both the physician and staff is essential. Numerous workshops are offered periodically. It is imperative that staff attends all Medicare-sponsored workshops in addition to gastroenterology-specific coding seminars. More and more physicians are now aware of their responsibility in the billing process and have begun to participate in the coding education along with their staff. This is a significant indicator of a physicians' intent to have a compliant and financially successful practice.

Cost-Benefit Analysis↗
PubMed1992

Differentiation of neuroblastoma cells correlates with an altered splicing pattern of tau RNA.

Morphological differentiation of N2A neuroblastoma cells is associated with an altered splicing of the gene of the microtubule-associated protein, tau. Two populations of RNA (coding for tau proteins containing three or four tubulin-binding motifs) are present in a similar proportion in undifferentiated neuroblastoma cells while in differentiated cells the proportion is changed in favour of that population coding for tau protein containing four tubulin-binding motifs. An increase in a high molecular weight tau isoforms correlates with the increase in the RNA population coding for four tubulin-binding motifs. A possible consequence of expressing a higher proportion of the tau protein containing four tubulin-binding motifs could be an increase in microtubule stability of differentiated neuroblastoma cells.

Animals↗
PubMed2004

Conservation and developmental control of alternative splicing in maebl among malaria parasites.

Genes of malaria parasites and other unicellular organisms have larger exons with fewer and smaller introns than metaozoans. Such differences in gene structure are perceived to extend to simpler mechanisms for transcriptional control and mRNA processing. Instead, we discovered a surprisingly complex level of post-transcriptional mRNA processing in analysis of maebl transcripts in several Plasmodium species. Mechanisms for internal alternative cis-splicing and exon skipping were active in multiple life cycle stages to change exon structure in the deduced coding sequence (CDS). The major alternatively spliced transcript utilized a less favorable acceptor splice site, which shifted codon triplet usage to a different CDS with a hydrophilic C terminus, changing the canonical type I membrane MAEBL product to a predicted soluble isoform. We found that developmental control of the alternative splicing pattern was distinct from the canonical splicing pattern. Western blot analysis indicated that MAEBL expression was better correlated with the appearance of the canonical ORF1 transcript. Together these data reveal that RNA metabolism in unicellular eukaryotes like Plasmodium is more sophisticated than believed and may have a significant role regulating gene expression in Plasmodium.

Alternative Splicing↗
PubMed1989

Induction of anaerobic gene expression in Rhodobacter capsulatus is not accompanied by a local change in chromosomal supercoiling as measured by a novel assay.

In the photosynthetic bacterium Rhodobacter capsulatus, the enzyme DNA gyrase has been implicated in the expression of genes for anaerobic metabolic processes such as nitrogen fixation and photosynthesis. To assess the involvement of supercoiling in anaerobic gene expression, we have developed an assay to detect in vivo changes in superhelicity of small regions of the bacterial chromosome. Our method is based on the preferential intercalaction of psoralen into supercoiled versus relaxed DNA, and we have demonstrated the sensitivity of the assay in vivo on chromosomal regions from 2 to 10 kilobases in size. In experiments with inhibitors of gyrase, the reactivity of individual chromosomal fragments to psoralen decreases by a factor of 1.8 compared with DNA from control cultures. We used our assay to determine whether there is a change in superhelicity near the genes coding for essential proteins for photosynthesis upon a shift from respiratory to anaerobic photosynthetic growth. For comparison, we also examined a restriction fragment containing the fbc operon, which codes for the subunits of cytochrome bc1, a membrane-bound electron transport complex utilized during both aerobic and anaerobic photosynthetic growth. During this shift in growth conditions, the puf and puh mRNAs, coding for structural polypeptides of the photosynthetic apparatus, underwent a six- to eightfold induction, while the amount of mRNA from the fbc locus remained constant. However, we detected no change in the superhelicity of either the genes for photosynthesis or those for the bc1 complex during this metabolic transition. Our data thus do not support a model in which stable changes in chromosomal superhelicity regulate anaerobic gene expression. We suggest instead that the requirement for DNA gyrase in the transcription of photosynthesis genes results from the requirement for a swivel near heavily transcribed regions of the chromosome.

Aerobiosis↗
PubMed1990

Diabetes-induced changes in guanine-nucleotide-regulatory-protein mRNA detected using synthetic oligonucleotide probes.

Synthetic oligonucleotide probes were designed to detect the alpha-subunits of the guanine-nucleotide-regulatory proteins (G-proteins) Gi-1, Gi-2, Gi-3 and Gs (Gi is inhibitory and Gs is stimulatory). Each probe detected a single major mRNA species in Northern blots of RNA extracted from a variety of tissues. A probe was designed to identify the two forms of G-protein beta-subunits, beta 1 and beta 2. This probe hybridised with a single 1.8-kb transcript (beta 2) in RNA from all tissues studied except for brain, where a less-abundant 3.4-kb transcript (beta 1) was also detected. These probes were used to assess whether the induction of diabetes, using streptozotocin, altered the levels of mRNA coding for specific G-protein components. In hepatocytes, diabetes caused a significant reduction in the number of transcripts coding for alpha-Gs, alpha-Gi-2 and alpha-Gi-3; mRNA for alpha-Gi-1 was undectable. In adipocytes, diabetes increased dramatically the mRNA coding for alpha-Gi-1 and alpha-Gi-3, whilst no significant changes occurred in the fractions coding for alpha-Gi-2 and alpha-Gs. No significant changes in the mRNA coding for G-protein alpha-subunits were observed in either brain, heart, skeletal muscle or kidney. Diabetes did not cause any significant changes in the mRNA coding for beta 2 in any tissue or cell population studied. Such results on the relative levels of mRNA encoding G-protein components was obtained by comparing equal amounts of total RNA from tissues of control and diabetic animals. G-protein mRNA levels were expressed relative to ribosomal 28S RNA levels and, in some instances, relative to transcripts for a structural protein called CHO-B. The total cellular levels of both RNA and DNA were assessed in the various tissues and cells studied. Major falls in RNA levels/cell appeared to occur in hepatocytes and to a lesser extent in adipocytes and skeletal muscle. Thus major reductions in G-protein transcripts occurred in hepatocytes. The detected changes in G-protein mRNA are discussed in relation to the available evidence on G-protein expression. We suggest that diabetes causes tissue-specific changes in the levels of mRNA for particular G-protein species; this may have consequences for the functioning of cellular signal-transduction mechanisms in the affected tissues.

Animals↗
PubMed1996

Cystic fibrosis deaths in the United States from 1979 through 1991. An analysis using multiple-cause mortality data.

OBJECTIVE: To analyze mortality trends among people who died with a diagnosis of cystic fibrosis from January 1, 1979, through December 31, 1991. METHODS: We reviewed death certificate reports in the Multiple-Cause Mortality Files compiled by the National Center for Health Statistics. RESULTS: Of the 26,866,600 decedents in the study period, 6500 had a diagnosis of cystic fibrosis listed on their death certificates; of these, 6014 (92.5%) had cystic fibrosis listed as the underlying cause of death. The age-adjusted mortality rate decreased 21%, from 2.4 per 1 million in 1979 to 1.9 per 1 million in 1991, with similar decrements among males and females. The median age of death increased from 15 years in 1979 to 23 years in 1991. During the study period, whites were 6 times more likely to die with a diagnosis of cystic fibrosis than were blacks, and 8 times more likely than were people of other races. Comorbid conditions mentioned on death certificates included obstructive lung disease in 744 (11.5%), pneumonia in 1192 (18.3%), and right heart failure in 986 (15.2%). CONCLUSIONS: From 1979 through 1991, the age-adjusted mortality rate for cystic fibrosis decreased and the median age of death among decedents with a diagnosis of cystic fibrosis increased. These results probably are due to improved treatment of the disease in children, although we cannot exclude other explanations for these findings, such as changes in death certification and coding or better diagnosis of the disease.

Adolescent↗