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PubMed2002

Structure and evolution of the Smith-Magenis syndrome repeat gene clusters, SMS-REPs.

An approximately 4-Mb genomic segment on chromosome 17p11.2, commonly deleted in patients with the Smith-Magenis syndrome (SMS) and duplicated in patients with dup(17)(p11.2p11.2) syndrome, is flanked by large, complex low-copy repeats (LCRs), termed proximal and distal SMS-REP. A third copy, the middle SMS-REP, is located between them. SMS-REPs are believed to mediate nonallelic homologous recombination, resulting in both SMS deletions and reciprocal duplications. To delineate the genomic structure and evolutionary origin of SMS-REPs, we constructed a bacterial artificial chromosome/P1 artificial chromosome contig spanning the entire SMS region, including the SMS-REPs, determined its genomic sequence, and used fluorescence in situ hybridization to study the evolution of SMS-REP in several primate species. Our analysis shows that both the proximal SMS-REP (approximately 256 kb) and the distal copy (approximately 176 kb) are located in the same orientation and derived from a progenitor copy, whereas the middle SMS-REP (approximately 241 kb) is inverted and appears to have been derived from the proximal copy. The SMS-REP LCRs are highly homologous (>98%) and contain at least 14 genes/pseudogenes each. SMS-REPs are not present in mice and were duplicated after the divergence of New World monkeys from pre-monkeys approximately 40-65 million years ago. Our findings potentially explain why the vast majority of SMS deletions and dup(17)(p11.2p11.2) occur at proximal and distal SMS-REPs and further support previous observations that higher-order genomic architecture involving LCRs arose recently during primate speciation and may predispose the human genome to both meiotic and mitotic rearrangements.

Abnormalities, Multiple↗

PubMed2002

Limitations on rate discrimination.

We investigated the limits of temporal pitch processing under conditions where the place and rate of stimulation on the basilar membrane were independent. Stimuli were harmonic complexes passed through a fixed bandpass filter and resembled filtered pulse trains. The task was to detect a difference in F0. When the harmonics were filtered between 3900-5400 Hz, presented monaurally, and summed in sine phase, subjects could perform the task at all FOs studied. However, when the pulse rate was doubled by summing components in alternating phase, thresholds increased with increasing F0 until the task was impossible at F0 = 300 Hz (pulse rate=600 pps). Thresholds improved again at higher FOs, presumably because some harmonics became resolved. The F0 at which this breakdown occurred decreased when the complexes were filtered into a lower frequency region, and increased when they were filtered into a higher region. In the highest region tested (7800-10800 Hz), all listeners could detect an increase of less than about 20% re: a pulse rate of 600 pps for alternating-phase complexes. Presenting a copy of the standard (lower-F0) stimulus to the contralateral ear during all intervals of a forced-choice trial improved performance markedly under conditions where monaural rate discrimination was very poor. This showed that temporal information is present in the auditory nerve that is unavailable to the temporal pitch mechanism, but which is accessible when a binaural cue is available. The results are compared to the inability of most cochlear implantees to detect increases in the rate of electrical pulse trains above about 300 pps. It is concluded that this inability is unlikely to result entirely from a central pitch limitation, because, with analogous acoustic stimulation, normal listeners can perform the task at substantially higher rates.

Adolescent↗

PubMed1998

The major structural protein of African swine fever virus, p73, is packaged into large structures, indicative of viral capsid or matrix precursors, on the endoplasmic reticulum.

African swine fever virus (ASFV) is a large enveloped DNA virus that shares the striking icosahedral symmetry of iridoviruses. To understand the mechanism of assembly of ASFV, we have been studying the biosynthesis and subcellular distribution of p73, the major structural protein of ASFV. Sucrose density sedimentation of lysates prepared from infected cells showed that newly synthesized p73 was incorporated into a complex with a size of 150 to 250 kDa. p73 synthesized by in vitro translation migrated at 70 kDa, suggesting that cellular and/or viral proteins are required for the formation of the 150- to 250-kDa complex. During a 2-h chase, approximately 50% of the newly synthesized pool of p73 bound to the endoplasmic reticulum (ER). During this period, the membrane-bound pool of p73, but not the cytosolic pool, formed large complexes of approximately 50,000 kDa. The complexes were formed via assembly intermediates, and the entire membrane-associated pool of p73 was incorporated into the 50,000-kDa complex within 2 h. The 50,000-kDa complexes containing p73 were also detected in virions secreted from cells. Immunoprecipitation of sucrose gradients with sera taken from hyperimmune pigs suggested that p73 was the major component of the 50,000-kDa complex. It is possible, therefore, that the complex contains between 600 and 700 copies of p73. The kinetics of complex formation and envelopment of p73 were similar, and complex formation and envelopment were both reversibly inhibited by cycloheximide, suggesting a functional link between complex assembly and ASFV envelopment. A protease protection assay detected 50,000-kDa complexes on the inside and outside of the membranes forming the viral envelope. The identification of a complex containing p73 beneath the envelope of ASFV suggests that p73 may be a component of the inner core shell or matrix of ASFV. The outer pool may represent p73 within the outer capsid layer of the virus. In summary, the data suggest that the assembly of the inner core matrix and outer capsid of ASFV takes place on the ER membrane during envelopment and that these structures are not preassembled in the cytosol.

African Swine Fever Virus↗

PubMed2006

Overexpression of mitochondrial peroxiredoxin-3 prevents left ventricular remodeling and failure after myocardial infarction in mice.

BACKGROUND: Mitochondrial oxidative stress and damage play major roles in the development and progression of left ventricular (LV) remodeling and failure after myocardial infarction (MI). We hypothesized that overexpression of the mitochondrial antioxidant, peroxiredoxin-3 (Prx-3), could attenuate this deleterious process. METHODS AND RESULTS: We created MI in 12- to 16-week-old, male Prx-3-transgenic mice (TG+MI, n=37) and nontransgenic wild-type mice (WT+MI, n=39) by ligating the left coronary artery. Prx-3 protein levels were 1.8 times higher in the hearts from TG than WT mice, with no significant changes in other antioxidant enzymes. At 4 weeks after MI, LV thiobarbituric acid-reactive substances in the mitochondria were significantly lower in TG+MI than in WT+MI mice (mean+/-SEM, 1.5+/-0.2 vs 2.2+/-0.2 nmol/mg protein; n=8 each, P<0.05). LV cavity dilatation and dysfunction were attenuated in TG+MI compared with WT+MI mice, with no significant differences in infarct size (56+/-1% vs 55+/-1%; n=6 each, P=NS) and aortic pressure between groups. Mean LV end-diastolic pressures and lung weights in TG+MI mice were also larger than those in WT+sham-operated mice but smaller than those in WT+MI mice. Improvement in LV function in TG+MI mice was accompanied by a decrease in myocyte hypertrophy, interstitial fibrosis, and apoptosis in the noninfarcted LV. Mitochondrial DNA copy number and complex enzyme activities were significantly decreased in WT+MI mice, and this decrease was also ameliorated in TG+MI mice. CONCLUSIONS: Overexpression of Prx-3 inhibited LV remodeling and failure after MI. Therapies designed to interfere with mitochondrial oxidative stress including the antioxidant Prx-3 might be beneficial in preventing cardiac failure.

Animals↗

PubMed1995

A functional cyclic AMP response element plays a crucial role in neuroendocrine cell type-specific expression of the secretory granule protein chromogranin A.

Chromogranin A, a soluble acidic protein, is a ubiquitous component of secretory vesicles throughout the neuroendocrine system. We reported previously the cloning and initial characterization of the mouse chromogranin A gene promoter, which showed that the promoter contains both positive and negative domains and that a proximal promoter spanning nucleotides -147 to +42 bp relative to the transcriptional start site is sufficient for neuroendocrine cell type-specific expression. The current study was undertaken to identify the particular elements within this proximal promoter that control tissue-specific expression. We found that deletion or point mutations in the potential cAMP response element (CRE) site at -68 bp virtually abolished promoter activity specifically in neuroendocrine (PC12 chromaffin or AtT20 corticotrope) cells, with little effect on activity in control (NIH3T3 fibroblast) cells; thus, the CRE box is necessary for neuroendocrine cell type-specific activity of the chromogranin A promoter. Furthermore, the effect of the CRE site is enhanced in the context of intact (wild-type) promoter sequences between -147 and -100 bp. DNase I footprint analysis showed that these regions (including the CRE box) bind nuclear proteins present in both neuroendocrine (AtT20) and control (NIH3T3) cells. In AtT20 cells, electrophoretic mobility shift assays and factor-specific antibody supershifts showed that an oligonucleotide containing the chromogranin A CRE site formed a single, homogeneous protein-DNA complex containing the CRE-binding protein CREB. However, in control NIH3T3 cells we found evidence for an additional immunologically unrelated protein in this complex. A single copy of this oligonucleotide was able to confer neuroendocrine-specific expression to a heterologous (thymidine kinase) promoter, albeit with less fold selectivity than the full proximal chromogranin A promoter. Hence, the CRE site was partially sufficient to explain the neuroendocrine cell type specificity of the promoter. The functional activity of the CRE site was confirmed through studies of the endogenous chromogranin A gene. Northern mRNA analysis showed that expression of the endogenous chromogranin A gene was stimulated seven- to eightfold by cAMP in PC12 cells, whereas no induction occurred in the NIH3T3 cells. Similar cAMP induction was obtained with the transfected chromogranin A promoter in PC12 cells, and abolition of the CRE site (by deletion or point mutation) eliminated the induction. Thus, the CRE site in the chromogranin A proximal promoter is functional and plays a crucial, indeed indispensable, role in neuroendocrine-specific expression of the gene. These results also provide insight into transcriptional mechanisms governing acquisition of the neuroendocrine secretory phenotype.

3T3 Cells↗

PubMed2000

Factor analysis of the Neuropsychological Screening Battery for Hispanics (NeSBHIS).

The Neuropsychological Screening Battery for Hispanics (NeSBHIS; Pontón et al., 1996) was developed to provide clinicians and researchers with appropriate tests and norms to assess the Latino population. However, the construct validity of the NeSBHIS is unclear, and its clinical utility is untested. This study provides data on the construct validity of this battery via factor analytic methodology. Five factors were identified: (a) a language factor, which included the Controlled Oral Word Association Test, the Pontón-Satz Boston Naming Test, and the Escala de Inteligencia Wechsler para Adultos (EIWA; Wechsler, Green, & Martinez, 1968) Digit Span; (b) a verbal learning factor, which included all the World Health Organization--University of California, Los Angeles Auditory Verbal Learning Test scores (Trials V, VII, and VIII); (c) an attentional-mental control factor, which included the EIWA Digit Symbol, Color Trails 1 and 2, and the EIWA Block Design; (d) a visuospatial factor, made up of the Rey-Osterrieth Complex Figure Test Copy and Memory and the Raven's Standard Progressive Matrices total score; and (e) a psychomotor factor, the Pin Test. This was a stable factor structure, suggesting that the NeSBHIS has a robust construct validity.

Adolescent↗

PubMed2006

GBF1, a cis-Golgi and VTCs-localized ARF-GEF, is implicated in ER-to-Golgi protein traffic.

The formation and maturation of membrane carriers that transport cargo from the ER to the Golgi complex involves the sequential action of the coat protein complexes COPII and COPI. Recruitment of COPI to nascent carriers requires activation of ADP-ribosylation factors by a BrefeldinA-sensitive guanine nucleotide exchange factor. Using new antisera and a GFP-tagged protein, we demonstrate that the exchange factor GBF1 localized to both Golgi membranes and peripheral puncta, near but separate from ER exit sites. Live cell imaging revealed that GFP-GBF1 associates dynamically with both membranes through rapid exchange with a large cytosolic pool. Treatment with BrefeldinA dramatically altered this rapid exchange, causing accumulation of GBF1 on both Golgi and peripheral puncta before eventual redistribution to the ER in a microtubule-dependent manner. Measurement of diffusion coefficients and subcellular fractionation confirmed this shift in GBF1 from cytosolic to membrane bound. BrefeldinA-induced accumulation of GBF1 coincided with loss of COPI from peripheral puncta. Furthermore, recruitment of GBF1 to cargo-containing peripheral puncta coincided with recruitment of COPI, but not COPII. Strikingly, microinjection of anti-GBF1 antibodies specifically caused dissociation of COPI from membranes. These observations strongly suggest that GBF1 regulates COPI membrane recruitment in the early secretory pathway.

ADP-Ribosylation Factors↗

PubMed1998

Utility of proverb interpretation measures with cardiac transplant candidates.

To assess metaphorical understanding and proverb interpretation in cardiac transplant candidates, the neuropsychological assessment records of 22 adults with end-stage cardiac disease under consideration for transplantation were analyzed. Neuropsychological tests consisted of the Controlled Oral Word Association Test, Halstead Category Test, Rey-Osterrieth Complex Figure Test (Copy), Trial Making Test, and summed scores for the proverb items of the WAIS-R Comprehension subtest. Analysis showed that the group tended to interpret proverbs literally. Proverb scores were significantly associated with scores on the Similarities and Picture Arrangement subtests of the WAIS-R. There was a moderate negative association between number of reported heart attacks and Proverb scores. The need for brief yet robust assessments including measures of inferential thinking and conceptualization in transplant candidates are highlighted.

Adult↗

PubMed2000

Different classes of retrotransposons in coniferous spruce species.

We have used the conservation of reverse transcriptase and integrase domains among retroelements to PCR-amplify three well-known types of these mobile genetic elements. Reverse transcriptase sequences from Ty1-copia were identified in spruce in this way, as well as integrase sequences from the Ty3-gypsy group. Using these sequences as probes against a Picea glauca genomic bank, individual members from the LTR (long terminal direct repeat) groups were obtained. A partial Ty1-copia-type element named Spcl was isolated along with a Ty3-gypsy-type element named Spdl. Genomic Southern hybridizations revealed the complexity and high copy number of LTR retrotransposons in black and white spruce.

Amino Acid Sequence↗

PubMedDate not supplied

Performance on the Hooper Visual Organizational Test in patients diagnosed with subcortical vascular dementia: relation to naming performance.

OBJECTIVE: To examine the performance of individuals with vascular dementia (VaD) on the Hooper Visual Organization Test (HVOT) and to determine the influence of naming on HVOT performance in this population. BACKGROUND: The HVOT is commonly administered to assess visuospatial perception among neurologic patients, but the test requires verbal identification of stimuli as well as spatial ability. Previous studies have examined the influence of naming on the HVOT, but the issue has not been systematically addressed in individuals with subcortical VaD. METHOD: Individuals with a diagnosis of VaD were administered the HVOT, three additional measures of visuospatial function (Block Design and Picture Completion subtests of the Wechsler Adult Intelligence Scale-Revised, Rey-Osterrieth Complex Figure Test copy trial), and the Boston Naming Test (BNT). RESULTS: On average, the VaD patients performed poorly compared with normative data on each of the cognitive measures, with the most pronounced deficit evident on the BNT. Regression analyses revealed that more than 60% of the variance in performance on the HVOT was accounted for by performance on the Block Design subtest of the Wechsler Adult Intelligence Scale-Revised; performance on the BNT did not contribute significantly. CONCLUSIONS: The results suggest that VaD patients perform below expectations on the HVOT and that the measure is robust to naming deficits in this population.

Brain↗

PubMed1990

Hydrodynamic characterization of the major intrinsic protein from the bovine lens fiber membranes. Extraction in n-octyl-beta-D-glucopyranoside and evidence for a tetrameric structure.

The major protein from the bovine lens fiber cell membranes, the 26-kilodalton protein (major intrinsic protein (MIP26)), has been solubilized in n-octyl-beta-D-glucopyranoside and purified by gel filtration. The final preparation was free of detergent micelles. Gel electrophoresis in denaturing conditions has confirmed the purity of the protein sample. A s20,w of 5.55 S, obtained from analytical ultracentrifugation, and a D20,w of 3.62 x 10(-7) cm2 s-1, obtained from photon correlation spectroscopy, resulted in a molar mass of (176,000 +/- 15,000) g/mol for the protein-detergent complex using the Svedberg relation. The measured detergent content of 0.71 g of detergent/g of protein resulted in a calculated partial specific volume of 0.787 cm3/g for the protein-detergent complex and a molar mass of 103,000 g/mol for the protein moiety. This allowed us to conclude that the protein-detergent complex contains four copies of the MIP26 protein, which supports the suggestion that in vivo the MIP26 molecules cluster in tetramers to form a pore-like structure.

Animals↗

PubMed1996

[Influence of the duration of recording in the reproducibility of the signal averaged electrocardiogram].

The authors studied the possibility of improving the reproducibility of the signal averaged ECG by increasing the number of averaged QRS complexes. One hundred patients were included in the study. In each cases, 400 QRS complexes were recorded on twice, consecutively, in strictly identical conditions. During each recording, the total duration of the amplified and averaged QRS complex (tQRS), the duration of the terminal signal below 40 microV (LAS) and the root mean square of the amplitude of the last 40 ms (RMS) were determined for 100, 200, 300 and 400 recorded QRS complexes. The presence of late potentials was defined as the positivity of two of the following criteria: tQRS > 114 ms, LAS > 38 ms, RMS < 20 microV. The number of contradictory diagnostic conclusions between two successive recordings of the same duration decreased progressively with the number of averaged QRS complexes: 10 for 100 QRS, 10 for 200 QRS, 9 for 300 QRS and 6 for 400 QRS complexes, but this improvement was not statistically significant. The absolute differences of tQRS and RMS between two successive recordings of the same duration were statistically different for the four durations of recording (p = 0.05) and there was a tendency towards statistical significance for LAS (p = 0.09). The best quantitative reproducibility of the 3 parameters was obtained with the recording of 300 QRS complexes. In conclusion, the reproducibility of the signal averaged ECG is improved when the number of average QRS complexes is increased. The authors' results suggests that reproducibility this is optimal with the amplification and averaging of 300 QRS complexes.

Action Potentials↗

PubMed1996

The Schizosaccharomyces pombe rad3 checkpoint gene.

The rad3 gene of Schizosaccharomyces pombe is required for checkpoint pathways that respond to DNA damage and replication blocks. We report the complete rad3 gene sequence and show that rad3 is the homologue of Saccharomyces cerevisiae ESR1 (MEC1/SAD3) and Drosophila melanogaster mei-41 checkpoint genes. This establishes Rad3/Mec1 as the only conserved protein which is required for all the DNA structure checkpoints in both yeast model systems. Rad3 is an inessential member of the 'lipid kinase' subclass of kinases which includes the ATM protein defective in ataxia telangiectasia patients. Mutational analysis indicates that the kinase domain is required for Rad3 function, and immunoprecipitation of overexpressed Rad3 demonstrates an associated protein kinase activity. The previous observation that rad3 mutations can be rescued by a truncated clone lacking the kinase domain may be due to intragenic complementation. Consistent with this, biochemical data suggest that Rad3 exists in a complex containing multiple copies of Rad3. We have identified a novel human gene (ATR) whose product is closely related to Rad3/Esr1p/Mei-41. ATR can functionally complement esr1-1 radiation sensitivity in S. cerevisiae. Together, the structural conservation and functional complementation suggest strongly that the mechanisms underlying the DNA structure checkpoints are conserved throughout evolution.

Adenosine Triphosphatases↗

PubMed1998

[A case of agraphia due to cerebral infarction in the left parietal lobe].

A case of agraphia due to cerebral infarction in the left parietal lobe was reported. A 63-year-old right-handed man was admitted to our hospital with writing disturbance. His spontaneous speech was fluent, and object naming, word fluency, repetition, verbal comprehension, and reading were fully preserved. However, his writing was slow and required effort. He showed hesitation in spontaneous writing and dictation. His power to copy was better than his power to write spontaneously or to take dictation, but he had some difficulty in copying letters and complex figures. The patient showed abnormal sequences of strokes and completed his strokes by piecing out of several fragments. CT scan and MRI showed a cerebral infarction in the left parietal lobe which included the superior parietal lobule. The amytal (Wada) test, which was performed via the left internal carotid artery, revealed that the left hemisphere was dominant for language. The characteristics of his agraphia much more closely resembled "apractic agraphia", as reported by Alexander et al (1992), than spatial agraphia or pure agraphia. Agraphia in this patient might result partially from the loss or unavailability of the memory of motor patterns necessary for writing letters.

Agraphia↗

PubMed2003

[Cotransformation of rice by bar and cecropin B gene expression cassettes lacking vector backbone sequences].

Whole plasmids are used in both Agrobacterium-mediated transformation and direct DNA transfer, generally leading to the integration of vector backbone sequences into the host genome along with the transgene(s). The undesirable vector backbone sequences may not only promote transgene rearrangements and affect transgene or endogenous gene expression negatively, but have disadvantage on the safe assessment of the transformants as "desert DNA". The direct DNA transforming systems can transfer minimal gene expression cassettes (promoter, open reading frame, terminator) into plant genome and generate "safer" transformants, also it can delivery multiple genes of agronomic relevance to economically-important crop plants. But there is seldom researching reports on the topic till now. The present paper studied some factors that affecting the transforming efficiency of liner gene expression cassettes to rice varieties by particle bombardment, and the integration patterns of the gene expression cassettes in rice genome were compared with that of the whole plasmids. The results showed: (1) The transforming frequency of gene expression cassettes to rice via particle bombardment is 0.1%-0.5%, the cotransforming frequency of non-selectable gene is about 50%-60% when two separate gene expression cassettes were used for transformation. Increasing the DNA mole content can increase the transforming frequency and the beside sequences of gene constructs may play an important role on the variation of transforming efficiency between different rice varieties. (2) It's reported that the selectable and non-selectable transgene expression cassettes generated low-copy-number transgenic plants with simple integration patterns. While our results showed that the non-selectable cecropin B gene cassette generated simple integration patterns with 1-3 copies in the rice genome, but the selectable bar gene cassette which got 4-14 copies had much more complex integration patterns than that of the whole plasmids which got 1-3 copies only. As the bar gene is promoted by the CaMV35 promoter, in which there is a 19 bp palindromic sequence could act as recombination hot spot and lead to DNA rearrangement, we presumed that the transgene recombination events happened during the integration course have generated the complex Southern patterns of bar gene expression cassette. The recombination character, the heredity behavior and the expression law of gene expression cassettes in the rice genomes will be reported in our future papers.

Acetyltransferases↗

PubMed1990

Characterization of Mycobacterium paratuberculosis and organisms of the Mycobacterium avium complex by restriction polymorphism of the rRNA gene region.

Nineteen Mycobacterium paratuberculosis strains, including strains of bovine, caprine, ovine, cervid, subhuman primate, and human origins, were compared with organisms of the M. avium complex by restriction fragment length polymorphism with a 5S rRNA gene probe as the reference DNA. Mycobacterial DNA was extracted, digested with several restriction enzymes, subjected to electrophoresis and Southern blotting, and then hybridized with a 5S rRNA gene probe from Escherichia coli. Hybridizing bands were visualized by autoradiography, and the sizes of the resulting rRNA fragments in kilobases were determined. Base substitutions were calculated on the basis of the number of shared fragments between species and strains. It was determined that M. paratuberculosis and the M. avium complex possess a single copy of the rRNA genes within their genomes and that the M. avium complex and M. paratuberculosis are a group of closely related organisms, likely with a common ancestral link. In proximity to the 5S rRNA gene exists a region or regions which display polymorphisms that are capable of species and subspecies differentiation. M. paratuberculosis strains isolated from humans, subhuman primates, and animals were found to be genetically identical to each other. M. paratuberculosis strains lacked the genetic heterogeneity (restriction fragment length polymorphisms) characteristic of most species, suggesting that this organism has unidirectional genetic selection. It is therefore assumed to be biologically isolated, occupying a unique and specific biological niche. This homogeneity was present in all strains, including those of animal and primate (subhuman and human) origin and strains isolated from different parts of the world.

Animals↗

PubMed1988

Multiple mechanisms for transcriptional regulation of the myc gene family in small-cell lung cancer.

The molecular mechanisms reported to regulate the expression of myc family genes are multiple and complex and include gene amplification, transcriptional activation, transcriptional attenuation, and mRNA stability. We have investigated which of these mechanisms are responsible for the extreme variation in myc gene family mRNA levels observed in human small-cell lung cancer cell lines. In addition to gene amplification, a block to nascent mRNA chain elongation, causing attenuation of transcription, is an important regulatory mechanism controlling the steady-state levels of c-myc and L-myc mRNA. The loss of transcriptional attenuation is correlated with overexpression of these two genes in cell lines which do not show gene amplification. Expression of c-myc mRNA appears to be dependent on promoter activity and attenuator function. In contrast, regulation of expression of the N-myc gene does not involve transcriptional attenuation; steady-state mRNA levels are correlated with promoter activity as well as gene amplification. We conclude that transcriptional regulation of each member of the myc gene family is accomplished by a different assortment of complex mechanisms, including gene copy number, promoter activation, and transcriptional attenuation. Interference at multiple points in this complex regulatory process appears to be an important mechanism by which small-cell lung cancer and other human tumors evade growth control.

Carcinoma, Small Cell↗

PubMed2000

IS1607, a single-copy insertion sequence-related element of the Mycobacterium tuberculosis complex.

The species specificity of IS1607, a new Mycobacterium tuberculosis complex insertion sequence-related element, was investigated. IS1607 was present as a single copy in M. tuberculosis, M. bovis and M. bovis BCG strains. This sequence also existed in M. africanum and M. microti, but was not present in 69 strains of 19 atypical mycobacterial species analyzed by using polymerase chain reaction (PCR) or Southern hybridization assay. IS1607 appears to be specific for the M. tuberculosis complex.

DNA Transposable Elements↗