Bisulfite genomic sequencing: systematic investigation of critical experimental parameters

Bisulfite genomic sequencing is the method of choice for the generation of methylation maps with single-base resolution. The method is based on the selective deamination of cytosine to uracil by treatment with bisulfite and the sequencing of subsequently generated PCR products. In contrast to cytosine, 5-methylcytosine does not react with bisulfite and can therefore be distinguished. In order to investigate the potential for optimization of the method and to determine the critical experimental parameters, we determined the influence of incubation time and incubation temperature on the deamination efficiency and measured the degree of DNA degradation during the bisulfite treatment. We found that maximum conversion rates of cytosine occurred at 55 degrees C (4-18 h) and 95 degrees C (1 h). Under these conditions at least 84-96% of the DNA is degraded. To study the impact of primer selection, homologous DNA templates were constructed possessing cytosine-containing and cytosine-free primer binding sites, respectively. The recognition rates for cytosine (>/=97%) and 5-methylcytosine (>/=94%) were found to be identical for both templates.

Identification and localization of a new human myotubularin-related protein gene, mtmr8, on 8p22-p23

Myotubularin and myotubularin-related proteins are dual-specificity phosphatases. Several myotubularin-related proteins have been identified in humans and mice. The members of the myotubularin protein family are highly conserved, from humans to yeast. Mutations in the human myotubularin gene (MTM1) lead to X-linked myotubular myopathy. Here we isolate and localize a novel putative myotubularin-related protein gene (MTMR8) on chromosome 8p22--p23,between the markers D8S550 and D8S265, by exon-trapping experiments and RT-PCR. Genomic sequencing revealed that the gene consists of 10 exons and spans approximately 43 kb. The corresponding cDNA is 7081 bp. The open reading frame predicts a protein of 549 amino acids and a calculated molecular mass of 63 kDa. Like myotubularin-related protein-5, MTMR8 has no dual-specificity phosphatase domain. It contains a double-helical motif similar to the SET interaction domain, which is thought to have a role in the control of cell proliferation.

Comparison of the ocular hypotensive lipid AGN 192024 with timolol: dosing, efficacy, and safety evaluation of a novel compound for glaucoma management

OBJECTIVE

To compare the safety and efficacy of the ocular hypotensive lipid AGN 192024 (Lumigan) with those of timolol.

METHODS

A 30-day, randomized, investigator-masked, clinical trial involving 100 patients with elevated intraocular pressure (IOP). Study medications were instilled topically. Doses of 0.003%, 0.01%, or 0.03% AGN 192024 were given once daily for 3 weeks then twice daily for 1 week, and vehicle control or 0.5% timolol was given twice daily for 4 weeks. Mean change in IOP from baseline was the primary efficacy variable. Safety parameters included adverse events, hyperemia grading, laser flare meter analysis, heart rate, and blood pressure.

RESULTS

Timolol and all 3 concentrations of AGN 192024 lowered IOP from baseline (P < .001). A dosage of 0.03% AGN 192024 once daily lowered IOP significantly more than timolol (P < or = .02) at every study visit except day 21 (P = .053) and provided better diurnal IOP control. Twice-daily dosing of AGN 192024 provided no clinically significant benefit over once-daily dosing. All treatment regimens were safe and well tolerated, with no clinically significant effects on heart rate or blood pressure and no between-group differences in the incidence of adverse events. The only significant ocular safety finding with AGN 192024 was a dose-related mild increase in conjunctival hyperemia.

CONCLUSIONS

Of the 3 concentrations tested, 0.03% AGN 192024 once daily had the best therapeutic profile. AGN 192024 was safe and well tolerated, and it provided superior ocular hypotensive efficacy and diurnal IOP control compared with timolol in patients with ocular hypertension and glaucoma.

Human-mouse comparative sequence analysis of the NEMO gene reveals an alternative promoter within the neighboring G6PD gene

NEMO (NFkappaB essential modulator) is a non-catalytic subunit of the cytokine-dependent IkappaB kinase complex that is involved in activation of the transcription factor NFkappaB. The human NEMO gene maps to Xq28 and is arranged head to head with the proximal G6PD gene. Mutations in NEMO have recently been associated with Incontinentia Pigmenti (Smahi et al., Nature 405 (2000) 466), an X-linked dominant disorder. Three alternative transcripts with different non-coding 5' exons (1a, 1b and 1c) of NEMO have been described. In order to identify regulatory elements that control alternative transcription we have established the complete genomic sequence of the murine orthologs Nemo and G6pdx. Sequence comparison suggests the presence of two alternative promoters for NEMO/Nemo. First, a CpG island is shared by both genes driving expression of the NEMO/Nemo transcripts containing exons 1b and 1c in one direction and the housekeeping gene G6PD/G6pdx in the opposite direction. In contrast to human, an additional variant of exon 1c, named 1c+, was identified in several tissues of the mouse. This larger exon utilizes an alternative donor site located 1594 bp within intron 1c. The putative second promoter for NEMO/Nemo transcripts starting with exon 1a is unidirectional, and not associated with a CpG island. Surprisingly, this promoter is located in the second intron of G6PD/G6pdx. It shows very low basal activity and may be involved in stress/time- and/or tissue-dependent expression of NEMO. To our knowledge, an overlapping gene order similar to the G6PD/NEMO complex has not been described before.

Combined effect of operational variables and enzyme activity on aqueous enzymatic extraction of oil and protein from soybean

The individual effect of two different enzymes-protease and cellulase-on oil and protein extraction yields combined with other process parameters-enzyme concentration, time of hydrolysis, particle size and solid-to-liquid ratio-was evaluated by Response Surface Methodology. The selection of the enzymes for the study was based on preliminary experiments that showed higher increments in the extraction yield with the use of the two enzymes when compared to hemicellulase and pectinase. The levels of the quantitative parameters studied were: i) enzyme concentration: 0.1, 0.45, 2 w/w %; ii) liquid-to-solid ratio: 0.05, 0.125, 0.2; iii) mean particle size: 212.5, 449.5, 855 µm; iv) time of hydrolysis: 30; 60; 120 min. Experimental data for both oil and protein extraction yields obtained with and without enzymes correlated very well with process parameters (P < 0.0001), resulting in models with high coefficient of determination for oil and protein extraction yields (r(2) = 0.9570 and r(2) = 0.9807, respectively). The use of protease resulted in significantly higher yields over the control (protein yield increased from 27.8 to 66.2%, oil yield increased from 41.8 to 58.7%) only when heat treated flour was used, or when non-heat treated flour with large particle sizes was used in the extraction. The yields of protein and oil from non-heat treated material in general decreased slightly with the use of enzymes.

Elevated DNA sequence diversity in the genomic region of the phosphatase PPP2R3L gene in the human pseudoautosomal region

The evolution, inheritance and recombination rate of genes located in the pseudoautosomal region 1 (PAR1) is exceptional within the human genome. Pseudoautosomal genes are identical on X and Y chromosomes and are not inherited in a sex linked manner. Due to an obligatory recombination event in male meiosis, pseudoautosomal genes are exchanged frequently between X and Y chromosomes. During the isolation, characterization and sequencing of a novel gene PPP2R3L, which was classified by sequence homology as a novel member of the protein phosphatase regulatory subunit families, it became apparent that cosmids of different origin harboring this gene are highly polymorphic between individuals, both at the nucleotide level and in the number.

The complex repeats of Dictyostelium discoideum

In the course of determining the sequence of the Dictyostelium discoideum genome we have characterized in detail the quantity and nature of interspersed repetitive elements present in this species. Several of the most abundant small complex repeats and transposons (DIRS-1; TRE3-A,B; TRE5-A; skipper; Tdd-4; H3R) have been described previously. In our analysis we have identified additional elements. Thus, we can now present a complete list of complex repetitive elements in D. discoideum. All elements add up to 10% of the genome. Some of the newly described elements belong to established classes (TRE3-C, D; TRE5-B,C; DGLT-A,P; Tdd-5). However, we have also defined two new classes of DNA transposable elements (DDT and thug) that have not been described thus far. Based on the nucleotide amount, we calculated the least copy number in each family. These vary between <10 up to >200 copies. Unique sequences adjacent to the element ends and truncation points in elements gave a measure for the fragmentation of the elements. Furthermore, we describe the diversity of single elements with regard to polymorphisms and conserved structures. All elements show insertion preference into loci in which other elements of the same family reside. The analysis of the complex repeats is a valuable data resource for the ongoing assembly of whole D. discoideum chromosomes.

Complex Arrangement of Genes within a 220-kb Region of Double-Duplicated DNA on Human 2q37.1

Gene duplication events are followed by divergence of initially identical gene copies, due to the subsequent accumulation of mutations. These mutations tend to be degenerative and may lead to either nonfunctionalization or subfunctionalization of the gene copies. Here we report the molecular characterization of a 220-kb genomic DNA fragment from human 2q37.1, in which a double duplication and a partial triplication event has taken place. As a result, this region contains four copies of alkaline phosphatase (P), four copies of the ECEL1 gene (X), two copies of a newly identified gene (N), and two copies of a cholinergic receptor subunit (R), in the order N-P-X-P-X-P-X-N-P-X-R-R. While three of the four ECEL1 copies, one copy of the phosphatase gene and one copy of the newly identified gene have lost their function, three phosphatase gene copies and the two receptor subunits are still functionally active and thus may provide an example for subfunctionalization of duplicated genes.

Molecular cloning of Xp11 breakpoints in two unrelated mentally retarded females with X;autosome translocations

Mental retardation is a very common and extremely heterogeneous disorder that affects about 3% of the human population. Its molecular basis is largely unknown, but many loci have been mapped to the X chromosome. We report on two mentally retarded females with X;autosome translocations and breakpoints in Xp11, viz., t(X;17)(p11;p13) and t(X;20)(p11;q13). (Fiber-) FISH analysis assigned the breakpoints to different subbands, Xp11.4 and Xp11.23, separated by approximately 8 Mb. High-resolution mapping of the X- chromosome breakpoints using Southern blot hybridization resulted in the isolation of breakpoint-spanning genomic subclones of 3 kb and 0. 5 kb. The Xp11.4 breakpoint is contained within a single copy sequence, whereas the Xp11.23 breakpoint sequence resembles an L1 repetitive element. Several expressed sequences map close to the breakpoints, but none was found to be inactivated. Therefore, mechanisms other than disruption of X-chromosome genes likely cause the phenotypes.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

A physical map of the human genome

The human genome is by far the largest genome to be sequenced, and its size and complexity present many challenges for sequence assembly. The International Human Genome Sequencing Consortium constructed a map of the whole genome to enable the selection of clones for sequencing and for the accurate assembly of the genome sequence. Here we report the construction of the whole-genome bacterial artificial chromosome (BAC) map and its integration with previous landmark maps and information from mapping efforts focused on specific chromosomal regions. We also describe the integration of sequence data with the map.

The DAPIN family: a novel domain links apoptotic and interferon response proteins

We report the discovery of a protein domain, hereafter referred to as DAPIN, in diverse vertebrate and viral proteins that is associated with tumor biology, apoptosis and inflammation. Based on a secondary structure prediction, we suggest an all-alpha fold for DAPIN, which is also adopted by apoptotic protein domains of the CARD, death domain and death effector domain type.

Topical ketorolac tromethamine 0.5% ophthalmic solution in ocular inflammation after cataract surgery

PURPOSE

To compare the efficacy and safety of ketorolac 0.5% ophthalmic solution with its vehicle in the treatment of ocular inflammation after cataract surgery and intraocular lens implantation.

DESIGN

Multicenter clinical study.

PARTICIPANTS

One hundred four patients were prospectively randomized, 52 patients in treatment group, 52 patients in control group.

METHODS

Patients received either ketorolac or vehicle four times daily in the operated eye for 14 days starting the day after surgery in a prospective, double-masked, randomized, parallel group study. Only patients with moderate or greater postoperative inflammation the day after surgery were enrolled.

MAIN OUTCOME MEASURES

The main outcome measures include inflammation (cell, flare, ciliary flush), intraocular pressure and visual acuity.

RESULTS

Ketorolac was significantly more effective than vehicle in reducing the manifestations of postoperative ocular inflammation, including: anterior chamber cells (P: = 0.002) and flare (P: = 0.009), conjunctival erythema (P: = 0.010), ciliary flush (P: = 0.022), photophobia (P: = 0.027), and pain (P: = 0.043). Five times as many patients were dropped from the study for lack of efficacy from the vehicle group (22/52) than from the ketorolac group (4/52; P: = 0.001). Ketorolac was found to be equally as safe as vehicle in terms of adverse events, changes in visual acuity, intraocular pressure, and biomicroscopic and ophthalmoscopic variables.

CONCLUSIONS

Ketorolac tromethamine 0.5% ophthalmic solution was significantly more effective than vehicle in the treatment of moderate or greater ocular inflammation following routine cataract surgery, while being as safe as vehicle.

Genome sequence of bovine herpesvirus 4, a bovine Rhadinovirus, and identification of an origin of DNA replication

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus of cattle. The complete long unique coding region (LUR) of BoHV-4 strain 66-p-347 was determined by a shotgun approach. Together with the previously published noncoding terminal repeats, the entire genome sequence of BoHV-4 is now available. The LUR consists of 108,873 bp with an overall G+C content of 41.4%. At least 79 open reading frames (ORFs) are present in this coding region, 17 of them unique to BoHV-4. In contrast to herpesvirus saimiri and human herpesvirus 8, BoHV-4 has a reduced set of ORFs homologous to cellular genes. Gene arrangement as well as phylogenetic analysis confirmed that BoHV-4 is a member of the genus Rhadinovirus. In addition, an origin of replication (ori) in the genome of BoHV-4 was identified by DpnI assays. A minimum of 1.69 kbp located between ORFs 69 and 71 was sufficient to act as a cis signal for replication.

Discovery of new human beta-defensins using a genomics-based approach

Epithelial beta-defensins are broad-spectrum cationic antimicrobial peptides that also act as chemokines for adaptive immune cells. In the human genome, all known defensin genes cluster to a <1 Mb region of chromosome 8p22-p23. To identify new defensin genes, the DNA sequence from a contig of large-insert genomic clones from the region containing human beta-defensin-2 (HBD-2) was analyzed for the presence of defensin genes. This sequence survey identified a novel beta-defensin, termed HBD-3. The HBD-3 gene contains two exons, is located 13 kb upstream from the HBD-2 gene, and it is transcribed in the same direction. A partial HBD-3 cDNA clone was amplified from cDNA derived from IL-1beta induced fetal lung tissue. The cDNA sequence encodes for a 67 amino acid peptide that is approximately 43% identical to HBD-2 and shares the beta-defensin six cysteine motif. By PCR analysis of two commercial cDNA panels, HBD-3 expression was detected in adult heart, skeletal muscle, placenta and in fetal thymus. From RT-PCR experiments, HBD-3 expression was observed in skin, esophagus, gingival keratinocytes, placenta and trachea. Furthermore, in fetal lung explants and gingival keratinocytes, HBD-3 mRNA expression was induced by IL-1beta. Additional sequence analysis identified the HE2 (human epididymis secretory protein) gene 17 kb upstream from the HBD-3 gene. One splice variant of this gene (HE2beta1) encodes a beta-defensin consensus cysteine motif, suggesting it represents a defensin gene product. HE2beta1 mRNA expression was detected in gingival keratinocytes and bronchial epithelia using RT-PCR analysis. The discovery of these novel beta-defensin genes may allow further understanding of the role of defensins in host immunity at mucosal surfaces.

Architecture and anatomy of the genomic locus encoding the human leukemia-associated transcription factor RUNX1/AML1

The RUNX1 gene on human chromosome 21q22.12 belongs to the 'runt domain' gene family of transcription factors (also known as AML/CBFA/PEBP2alpha). RUNX1 is a key regulator of hematopoiesis and a frequent target of leukemia associated chromosomal translocations. Here we present a detailed analysis of the RUNX1 locus based on its complete genomic sequence. RUNX1 spans 260 kb and its expression is regulated through two distinct promoter regions, that are 160 kb apart. A very large CpG island complex marks the proximal promoter (promoter-2), and an additional CpG island is located at the 3' end of the gene. Hitherto, 12 different alternatively spliced RUNX1 cDNAs have been identified. Genomic sequence analysis of intron/exon boundaries of these cDNAs has shown that all consist of properly spliced authentic coding regions. This indicates that the large repertoire of RUNX1 proteins, ranging in size between 20-52 kDa, are generated through usage of alternatively spliced exons some of which contain in frame stop codons. The gene's introns are largely depleted of repetitive sequences, especially of the LINE1 family. The RUNX1 locus marks the transition from a ~1 Mb of gene-poor region containing only pseudogenes, to a gene-rich region containing several functional genes. A search for RUNX1 sequences that may be involved in the high frequency of chromosomal translocations revealed that a 555 bp long segment originating in chromosome 11 FLI1 gene was transposed into RUNX1 intron 4.1. This intron harbors the t(8;21) and t(3;21) chromosomal breakpoints involved in acute myeloid leukemia. Interestingly, the FLI1 homologous sequence contains a breakpoint of the t(11;22) translocation associated with Ewing's tumors, and may have a similar function in RUNX1.

MethDB--a public database for DNA methylation data

Methylation of cytosine in the 5 position of the pyrimidine ring is a major modification of the DNA in most organisms. In eukaryotes, the distribution and number of 5-methylcytosines (5mC) along the DNA is heritable but can also change with the developmental state of the cell and as a response to modifications of the environment. While DNA methylation probably has a number of functions, scientific interest has recently focused on the gene silencing effect methylation can have in eukaryotic cells. In particular, the discovery of changes in the methylation level during cancer development has increased the interest in this field. In the past, a vast amount of data has been generated with different levels of resolution ranging from 5mC content of total DNA to the methylation status of single nucleotides. We present here a database for DNA methylation data that attempts to unify these results in a common resource. The database is accessible via WWW (http://www.methdb.de). It stores information about the origin of the investigated sample and the experimental procedure, and contains the DNA methylation data. Query masks allow for searching for 5mC content, species, tissue, gene, sex, phenotype, sequence ID and DNA type. The output lists all available information including the relative gene expression level. DNA methylation patterns and methylation profiles are shown both as a graphical representation and as G/A/T/C/5mC-sequences or tables with sequence positions and methylation levels, respectively.

Downregulation of Hedgehog signaling is required for organogenesis of the small intestine in Xenopus

Hedgehog ligands interact with receptor complexes containing Patched (PTC) and Smoothened (SMO) proteins to regulate many aspects of development. The mutation W535L (SmoM2) in human Smo is associated with basal cell skin cancers, causes constitutive, ligand-independent signaling through the Hedgehog pathway, and provides a powerful means to test effects of unregulated Hedgehog signaling. Expression of SmoM2 in Xenopus embryos leads to developmental anomalies that are consistent with known requirements for regulated Hedgehog signaling in the eye and pancreas. Additionally, it results in failure of midgut epithelial cytodifferentiation and of the intestine to lengthen and coil. The midgut mesenchyme shows increased cell numbers and attenuated expression of the differentiation marker smooth muscle actin. With the exception of the pancreas, differentiation of foregut and hindgut derivatives is unaffected. The intestinal epithelial abnormalities are reproduced in embryos or organ explants treated directly with active recombinant hedgehog protein. Ptc mRNA, a principal target of Hedgehog signaling, is maximally expressed at stages corresponding to the onset of the intestinal defects. In advanced embryos expressing SmoM2, Ptc expression is remarkably confined to the intestinal wall. Considered together, these findings suggest that the splanchnic mesoderm responds to endodermal Hedgehog signals by inhibiting the transition of midgut endoderm into intestinal epithelium and that attenuation of this feedback is required for normal development of the vertebrate intestine.

Drinks like a fish: zebra fish (Danio rerio) as a behavior genetic model to study alcohol effects

Zebra fish may be an ideal vertebrate model system for numerous human diseases with which the genetics and biological mechanisms of the disease may be studied. Zebra fish has been successfully used in developmental genetics, and recently, neurobiologists have also started to study this species. A potentially interesting target disease amenable for analysis with zebra fish is drug addiction, e.g. alcoholism. Although genetic tools to manipulate the genome of zebra fish are available, appropriate phenotypical testing methods are often lacking. In this paper, we describe basic behavioral tests to investigate the acute effects of alcohol on zebra fish. These behavioral paradigms will be useful for the genetic and biological analysis of acute and chronic drug effects as well as addiction. In addition to presenting findings for the acute effects of alcohol, we briefly describe our strategy for generating and screening mutants. We hope that our pilot work will facilitate the future development of behavioral tests and the use of zebra fish in the genetic analysis of the biological effects of drugs of abuse.

A regulator of transcriptional elongation controls vertebrate neuronal development

The development of distinct vertebrate neurons is defined by the unique profiles of genes that neurons express. It is accepted that neural genes are regulated at the point of transcription initiation, but the role of messenger RNA elongation in neural gene regulation has not been examined. Here we describe the mutant foggy, identified in a genetic screen for mutations that affect neuronal development in zebrafish, that displayed a reduction of dopamine-containing neurons and a corresponding surplus of serotonin-containing neurons in the hypothalamus. Positional cloning disclosed that Foggy is a brain-enriched nuclear protein that is structurally related to the transcription elongation factor Spt5 (refs 5-12). Foggy is not part of the basic transcription apparatus but a phosphorylation-dependent, dual regulator of transcription elongation. The mutation disrupts its repressive but not its stimulatory activity. Our results provide molecular, genetic and biochemical evidence that negative regulators of transcription elongation control key aspects of neuronal development.

Large-scale methylation analysis of human genomic DNA reveals tissue-specific differences between the methylation profiles of genes and pseudogenes

Cytosine in CpG dinucleotides is frequently found to be methylated in the DNA of higher eukaryotes and differential methylation has been proposed to be a key element in the organization of gene expression in man. To address this question systematically, we used bisulfite genomic sequencing to study the methylation patterns of three X-linked genes and one autosomal pseudogene in two adult individuals and across nine different tissues. Two of the genes, SLC6A8 and MSSK1, are tissue-specifically expressed. CDM is expressed ubiquitously. The pseudogene, psi SLC6A8, is exclusively expressed in the testis. The promoter regions of the SLC6A8, MSSK1 and CDM genes were found to be essentially unmethylated in all tissues, regardless of their relative expression level. In contrast, the pseudogene psi SLC6A8 shows high methylation of the CpG islands in all somatic tissues but complete demethylation in testis. Methylation profiles in different tissues are similar in shape but not identical. The data for the two investigated individuals suggest that methylation profiles of individual genes are tissue specific. Taken together, our findings support a model in which the bodies of the genes are predominantly methylated and thus insulated from the interaction with DNA-binding proteins. Only unmethylated promoter regions are accessible for binding and interaction. Based on this model we propose to use DNA methylation studies in conjunction with large-scale sequencing approaches as a tool for the prediction of cis-acting genomic regions, for the identification of cryptic and potentially active CpG islands and for the preliminary distinction of genes and pseudogenes.

The structure and gene repertoire of an ancient red algal plastid genome

Photosynthetic eukaryotes can, according to features of their chloroplasts, be divided into two major groups: the red and the green lineage of plastid evolution. To extend the knowledge about the evolution of the red lineage we have sequenced and analyzed the chloroplast genome (cp-genome) of Cyanidium caldarium RK1, a unicellular red alga (AF022186). The analysis revealed that this genome shows several unusual structural features, such as a hypothetical hairpin structure in a gene-free region and absence of large repeat units. We provide evidence that this structural organization of the cp-genome of C. caldarium may be that of the most ancient cp-genome so far described. We also compared the cp-genome of C. caldarium to the other known cp-genomes of the red lineage. The cp-genome of C. caldarium cannot be readily aligned with that of Porphyra purpurea, a multicellular red alga, or Guillardia theta due to a displacement of a region of the cp-genome. The phylogenetic tree reveals that the secondary endosymbiosis, through which G. theta evolved, took place after the separation of the ancestors of C. caldarium and P. purpurea. We found several genes unique to the cp-genome of C. caldarium. Five of them seem to be involved in the building of bacterial cell envelopes and may be responsible for the thermotolerance of the chloroplast of this alga. Two additional genes may play a role in stabilizing the photosynthetic machinery against salt stress and detoxification of the chloroplast. Thus, these genes may be unique to the cp-genome of C. caldarium and may be required for the endurance of the extreme living conditions of this alga.

Propofol versus midazolam for conscious sedation guided by processed EEG during endoscopic retrograde cholangiopancreatography: a prospective, randomized, double-blind study

BACKGROUND AND STUDY AIMS

Endoscopic retrograde cholangiopancreatography (ERCP) is a complex procedure, which requires appropriate sedation. The aim of this prospective, randomized, double-blind study was to compare the quality and characteristics of sedation with midazolam or propofol in patients undergoing ERCP.

PATIENTS AND METHODS

A total of 32 patients undergoing ERCP were randomly allocated for sedation with propofol (n = 15) or midazolam (n = 17). Blood pressure, heart rate, and O2 saturation were monitored. Sedation was maintained at near constant levels by use of the spectral edge frequency (SEF) technique, an EEG-based method for measuring the depth of sedation. Clinical variables, patient cooperation, time to recovery, and amnesia served as outcome variables.

RESULTS

There was no significant difference between the two study groups in patient characteristics. The "target SEF" was 13.6 +/- 0.7 Hz for the propofol group and 14.8 +/- 1.1 Hz for the midazolam group (n.s.). The only clinical parameter with a significant difference between the groups was the percent of time in which the heart rate deviated more than 20% from baseline for at least 2 minutes, i.e. 14.6 +/- 2.0 % for propofol and 48.2 +/- 38.0% for midazolam (P<0.01). Patient cooperation was better in the propofol group than in the midazolam group (full cooperation, 13/15 vs. 1/17, respectively; P<0.001). Patient recovery was significantly quicker in the propofol group (P<0.001). The degree of amnesia was similar in both groups; no patient in either group remembered details of the procedure.

CONCLUSIONS

ERCP is better tolerated by patients sedated with propofol compared with midazolam, with a shorter recovery time and lesser hemodynamic side effects. Propofol should be considered to be the sedative drug of choice for ERCP.

N-myc downstream-regulated gene 1 is mutated in hereditary motor and sensory neuropathy-Lom

Hereditary motor and sensory neuropathies, to which Charcot-Marie-Tooth (CMT) disease belongs, are a common cause of disability in adulthood. Growing awareness that axonal loss, rather than demyelination per se, is responsible for the neurological deficit in demyelinating CMT disease has focused research on the mechanisms of early development, cell differentiation, and cell-cell interactions in the peripheral nervous system. Autosomal recessive peripheral neuropathies are relatively rare but are clinically more severe than autosomal dominant forms of CMT, and understanding their molecular basis may provide a new perspective on these mechanisms. Here we report the identification of the gene responsible for hereditary motor and sensory neuropathy-Lom (HMSNL). HMSNL shows features of Schwann-cell dysfunction and a concomitant early axonal involvement, suggesting that impaired axon-glia interactions play a major role in its pathogenesis. The gene was previously mapped to 8q24.3, where conserved disease haplotypes suggested genetic homogeneity and a single founder mutation. We have reduced the HMSNL interval to 200 kb and have characterized it by means of large-scale genomic sequencing. Sequence analysis of two genes located in the critical region identified the founder HMSNL mutation: a premature-termination codon at position 148 of the N-myc downstream-regulated gene 1 (NDRG1). NDRG1 is ubiquitously expressed and has been proposed to play a role in growth arrest and cell differentiation, possibly as a signaling protein shuttling between the cytoplasm and the nucleus. We have studied expression in peripheral nerve and have detected particularly high levels in the Schwann cell. Taken together, these findings point to NDRG1 having a role in the peripheral nervous system, possibly in the Schwann-cell signaling necessary for axonal survival.

Comparative genome sequence analysis of the Bpa/Str region in mouse and Man

The progress of human and mouse genome sequencing programs presages the possibility of systematic cross-species comparison of the two genomes as a powerful tool for gene and regulatory element identification. As the opportunities to perform comparative sequence analysis emerge, it is important to develop parameters for such analyses and to examine the outcomes of cross-species comparison. Our analysis used gene prediction and a database search of 430 kb of genomic sequence covering the Bpa/Str region of the mouse X chromosome, and 745 kb of genomic sequence from the homologous human X chromosome region. We identified 11 genes in mouse and 13 genes and two pseudogenes in human. In addition, we compared the mouse and human sequences using pairwise alignment and searches for evolutionary conserved regions (ECRs) exceeding a defined threshold of sequence identity. This approach aided the identification of at least four further putative conserved genes in the region. Comparative sequencing revealed that this region is a mosaic in evolutionary terms, with considerably more rearrangement between the two species than realized previously from comparative mapping studies. Surprisingly, this region showed an extremely high LINE and low SINE content, low G+C content, and yet a relatively high gene density, in contrast to the low gene density usually associated with such regions.

The DNA sequence of human chromosome 21

Chromosome 21 is the smallest human autosome. An extra copy of chromosome 21 causes Down syndrome, the most frequent genetic cause of significant mental retardation, which affects up to 1 in 700 live births. Several anonymous loci for monogenic disorders and predispositions for common complex disorders have also been mapped to this chromosome, and loss of heterozygosity has been observed in regions associated with solid tumours. Here we report the sequence and gene catalogue of the long arm of chromosome 21. We have sequenced 33,546,361 base pairs (bp) of DNA with very high accuracy, the largest contig being 25,491,867 bp. Only three small clone gaps and seven sequencing gaps remain, comprising about 100 kilobases. Thus, we achieved 99.7% coverage of 21q. We also sequenced 281,116 bp from the short arm. The structural features identified include duplications that are probably involved in chromosomal abnormalities and repeat structures in the telomeric and pericentromeric regions. Analysis of the chromosome revealed 127 known genes, 98 predicted genes and 59 pseudogenes.

Differential gene expression by endothelial cells in distinct angiogenic states

Angiogenesis is a complex process that can be regarded as a series of sequential events comprising a variety of tissue cells. The major problem when studying angiogenesis in vitro is the lack of a model system mimicking the various aspects of the process in vivo. In this study we have used two in vitro models, each representing different and distinct aspects of angiogenesis. Differentially expressed genes in the two culture forms were identified using the suppression subtractive hybridization technique to prepare subtracted cDNA libraries. This was followed by a differential hybridization screen to pick up overexpressed clones. Using comparative multiplex RT-PCR we confirmed the differential expression and showed differences up to 14-fold. We identified a broad range of genes already known to play an important role during angiogenesis like Flt1 or TIE2. Furthermore several known genes are put into the context of endothelial cell differentiation, which up to now have not been described as being relevant to angiogenesis, like NrCAM, Claudin14, BMP-6, PEA-15 and PINCH. With ADAMTS4 and hADAMTS1/METH-1 we further extended the set of matrix metalloproteases expressed and regulated by endothelial cells.

Criteria for gene identification and features of genome organization: analysis of 6.5 Mb of DNA sequence from human chromosome 21

To establish criteria for and the limitations of novel gene identification, to identify novel genes of potential relevance to Down Syndrome and to investigate features of genome organization, 6. 550kb. In total, 41 novel gene models were predicted, and for a subset of these, RT-PCR experiments helped to verify and refine the models, and were used to assess expression in early development and in adult brain regions of potential relevance to Down syndrome. Results suggest generally low and/or restricted patterns of expression, and also reveal examples of complex alternative processing, especially in brain, that may have important implications for regulation of protein function. Analysis of complete gene structures of the known genes identified a number of very large introns, a number of very short intergenic distances, and at least one potentially bi-directional promoter. At least 3/4 of known genes and 1/2 of predicted genes are associated with CpG islands. For novel genes, three cases of overlapping genes are predicted. Results of these analyses illustrate some of the complexities inherent in mammalian genome organization and some of the limitations of current sequence analysis technologies. They also doubled the number of potential genes within the region.

Characterization of a novel gene, C21orf6, mapping to a critical region of chromosome 21q22.1 involved in the monosomy 21 phenotype and of its murine ortholog, orf5

Phenotypic and molecular analyses of patients with partial chromosome 21 monosomy enabled us to define a region, spanning 2.4 Mb between D21S190 and D21S226, associated with arthrogryposis, mental retardation, hypertonia, and several facial anomalies. The markers of the region were used to screen a total human PAC library (Ioannou, RZPD). We isolated 57 PACs, which formed primary contigs. EST clusters (UNIGENE collection) located in a 6-Mb interval, between D21S260 and D21S263, were mapped in individual bacterial clones. We mapped the WI-17843 cluster to the PAC clone J12100, which contains the two anchor markers LB10T and LA329. The open reading frame extends over 960 bp, with three putative start codons. The 1695-bp cDNA containing a polyadenylation signal should correspond to the full-length cDNA. From the genomic sequence, we deduced that the gene contained five exons and that there was a putative promoter sequence upstream from exon 1. In silico screening of DNA databases revealed similarity with a murine EST. The corresponding cDNA (1757 bp) sequence was very similar (>85%) to the human cDNA and had an open reading frame of 876 nucleotides. Somatic hybrid mapping localized the cDNA to mouse chromosome 16. EST analyses and RT-PCR indicated that the third exon in the human gene (exon 2 in the mouse) undergoes alternative splicing. Northern blot hybridization showed that the gene was ubiquitously expressed in humans and mice. The longest mouse clone was used to generate riboprobes, which were hybridized to murine embryos at stages E-9.5, E-10.5, E-12.5, E-13.5, and E-14.5-15, to study the pattern of expression during development. Ubiquitous labeling was observed, with strong signals restricted to limited areas of the telencephalon, the mesencephalon, and the interrhombomeric regions in the central nervous system, and other regions of the body such as the limb buds, branchial arches, and somites.

Comparative sequence analysis of the MECP2-locus in human and mouse reveals new transcribed regions

Comparative sequence analysis facilitates the identification of evolutionarily conserved regions, that is, gene-regulatory elements, which can not be detected by analyzing one species only. Sequencing of a 152-kb region on human Chromosome (Chr) Xq28 and of the synthenic 123 kb on mouse Chr XC identified the MECP2/Mecp2 locus, which is flanked by the gene coding for Interleukin-1 receptor associated kinase (IRAK/Il1rak) and the red opsin gene (RCP/Rsvp). By comparative sequence analysis, we identified a previously unknown, non-coding 5' exon embedded in a CpG island associated with MECP2/Mecp2. Thus, the MECP2/Mecp2 gene is comprised of four exons instead of three. Furthermore, sequence comparison 3' to the previously reported polyadenylation signal revealed a highly conserved region of 8.5 kb terminating in an alternative polyadenylation signal. Northern blot analysis verified the existence of two main transcripts of 1.9 kb and approximately 10 kb, respectively. Both transcripts exhibit tissue-specific expression patterns and have almost identical short half-lifes. The approximately 10-kb transcript corresponds to a giant 3' UTR contained in the fourth exon of MECP2. The long 3' UTR and the newly identified first intron of MECP2/Mecp2 are highly conserved in human and mouse. Furthermore, the human MECP2 locus is heterogeneous with respect to its DNA composition. We postulate that it represents a boundary between two H3 isochores that has not been observed previously.

MethTools--a toolbox to visualize and analyze DNA methylation data

The Bisulfite Genomic Sequencing technique has found wide acceptance for the generation of DNA-methylation maps with single-base resolution. The method is based on the selective deamination of cytosine to uracil (and subsequent conversion to thymine via PCR), whereas 5-methylcytosine residues remain unchanged. Methylation maps are created by the comparison of bisulfite converted sequences with the untreated genomic sequence. 'MethTools' is a collection of software tools that replaces the time-consuming manual comparison process, generates graphical outputs of methylation patterns and methyl-ation density, estimates the systematic error of the experiment and searches for conserved methylated nucleotide patterns. The programs are written in Perl 5 and C, and the source code can be downloaded. All tools run independently but the programs are interfaced. Thus, a script can perform the entire analysis procedure automatically. In addition, a web-based remote analysis service is offered. Both the source code and the remote analysis are available at http://genome.imb-jena.de/methtools/

Comparative analysis of the PCOLCE region in Fugu rubripes using a new automated annotation tool

The Japanese pufferfish Fugu rubripes with a genome of about 400 Mb is becoming increasingly recognized as a vertebrate model organism for comparative gene analysis (see Elgar 1996 for review). We have isolated and sequenced two Fugu cosmids spanning a genomic region of 66 kb containing the Fugu homolog to the human PCOLCE-I (Glöckner et al. 1998). We then examined if RUMMAGE-DP, a newly developed analysis tool for gene discovery which was designed for human and mouse genomic DNA, can be used for automatic annotation of Fugu genomic sequence. The exon prediction programs contained in RUMMAGE-DP performed better overall for the human sequence than for the Fugu contig. The GENSCAN program was the only exon prediction programme that performed equally well for both organisms. We show that RUMMAGE-DP is very useful in automatic analysis of Fugu sequences. Comparative analysis of the genomic structure of the PCOLCE-I genes in Fugu and human reveals that the exon/intron structure throughout the protein coding region is almost identical. We defined an additional domain based on the high degree of similarity of 26 aa between mammals and Fugu. The PCOLCE-I protein in both organisms contains two highly conserved CUB domains. Exons 6 and 7 are the only coding exons that differ in length between the two species. We assume that these exons do not code for any catalytic domain of the protein. Analysis of the remaining five Fugu genes within the 66 kb interval revealed no conserved synteny with the corresponding human 7q22 region.

A genome-wide survey of RAS transformation targets

An important aspect of multi-step tumorigenesis is the mutational activation of genes of the RAS family, particularly in sporadic cancers of the pancreas, colon, lung and myeloid system. RAS genes encode small GTP-binding proteins that affect gene expression in a global way by acting as major switches in signal transduction processes, coupling extracellular signals with transcription factors. Oncogenic forms of RAS are locked in their active state and transduce signals essential for transformation, angiogenesis, invasion and metastasis via downstream pathways involving the RAF/MEK/ERK cascade of cytoplasmic kinases, the small GTP-binding proteins RAC and RHO, phosphatidylinositol 3-kinase and others. We have used subtractive suppression hybridization (SSH), a PCR-based cDNA subtraction technique, to contrast differential gene expression profiles in immortalized, non-tumorigenic rat embryo fibroblasts and in HRAS- transformed cells. Sequence and expression analysis of more than 1,200 subtracted cDNA fragments revealed transcriptional stimulation or repression of 104 ESTs, 45 novel sequences and 244 known genes in HRAS- transformed cells compared with normal cells. Furthermore, we identified common and distinct targets in cells transformed by mutant HRAS, KRAS and NRAS, as well as 61 putative target genes controlled by the RAF/MEK/ERK pathway in reverted cells treated with the MEK-specific inhibitor PD 98059.

Sequence, structure, and evolution of a complete human olfactory receptor gene cluster

The olfactory receptor (OR) gene cluster on human chromosome 17p13.3 was subjected to mixed shotgun automated DNA sequencing. The resulting 412 kb of genomic sequence include 17 OR coding regions, 6 of which are pseudogenes. Six of the coding regions were discovered only upon genomic sequencing, while the others were previously reported as partial sequences. A comparison of DNA sequences in the vicinity of the OR coding regions revealed a common gene structure with an intronless coding region and at least one upstream noncoding exon. Potential gene control regions including specific pyrimidine:purine tracts and Olf-1 sites have been identified. One of the pseudogenes apparently has evolved into a CpG island. Four extensive CpG islands can be discerned within the cluster, not coupled to specific OR genes. The cluster is flanked at its telomeric end by an unidentified open reading frame (C17orf2) with no significant similarity to any known protein. A high proportion of the cluster sequence (about 60%) belongs to various families of interspersed repetitive elements, with a clear predominance of LINE repeats. The OR genes in the cluster belong to two families and seven subfamilies, which show a relatively high degree of intermixing along the cluster, in seemingly random orientations. This genomic organization may be best accounted for by a complex series of evolutionary events.

Mice lacking alpha-synuclein display functional deficits in the nigrostriatal dopamine system

alpha-Synuclein (alpha-Syn) is a 14 kDa protein of unknown function that has been implicated in the pathophysiology of Parkinson's disease (PD). Here, we show that alpha-Syn-/- mice are viable and fertile, exhibit intact brain architecture, and possess a normal complement of dopaminergic cell bodies, fibers, and synapses. Nigrostriatal terminals of alpha-Syn-/- mice display a standard pattern of dopamine (DA) discharge and reuptake in response to simple electrical stimulation. However, they exhibit an increased release with paired stimuli that can be mimicked by elevated Ca2+. Concurrent with the altered DA release, alpha-Syn-/- mice display a reduction in striatal DA and an attenuation of DA-dependent locomotor response to amphetamine. These findings support the hypothesis that alpha-Syn is an essential presynaptic, activity-dependent negative regulator of DA neurotransmission.

Mutations in a new gene, encoding a zinc-finger protein, cause tricho-rhino-phalangeal syndrome type I

Tricho-rhino-phalangeal syndrome type I (TRPS I, MIM 190350) is a malformation syndrome characterized by craniofacial and skeletal abnormalities and is inherited in an autosomal dominant manner. TRPS I patients have sparse scalp hair, a bulbous tip of the nose, a long flat philtrum, a thin upper vermilion border and protruding ears. Skeletal abnormalities include cone-shaped epiphyses at the phalanges, hip malformations and short stature. We assigned TRPS1 to human chromosome 8q24. It maps proximal of EXT1, which is affected in a subgroup of patients with multiple cartilaginous exostoses and deleted in all patients with TRPS type II (TRPS II, or Langer-Giedion syndrome, MIM 150230; ref.2-5). We have positionally cloned a gene that spans the chromosomal breakpoint of two patients with TRPS I and is deleted in five patients with TRPS I and an interstitial deletion. Northern-blot analyses revealed transcripts of 7 and 10.5 kb. TRPS1has seven exons and an ORF of 3,843 bp. The predicted protein sequence has two potential nuclear localization signals and an unusual combination of different zinc-finger motifs, including IKAROS-like and GATA-binding sequences. We identified six different nonsense mutations in ten unrelated patients. Our findings suggest that haploinsufficiency for this putative transcription factor causes TRPS I.

The seven-transmembrane receptor smoothened cell-autonomously induces multiple ventral cell types

Sonic Hedgehog (Shh) is a secreted protein that controls cell fate and mitogenesis in the developing nervous system. Here we show that a constitutively active form of Smoothened (Smo-M2) mimics concentration-dependent actions of Shh in the developing neural tube, including activation of ventral marker genes (HNF3beta, patched, Nkx2.2, netrin-1), suppression of dorsal markers (Pax-3, Gli-3, Ephrin A5) and induction of ventral neurons (dopaminergic, serotonergic) and ventrolateral motor neurons (Islet-1+, Islet-2+, HB9+) and interneurons (Engrailed-1+, CHX10+). Furthermore, Smo-M2's patterning activities were cell autonomous, occurring exclusively in cells expressing Smo-M2. These findings suggest that Smo is a key signaling component in the Hh receptor and that Shh patterns the vertebrate nervous system as a morphogen, rather than through secondary relay signals.

Microarrays--chances and challenges

Microarrays are a powerful tool in modern genome analysis. The massive parallel analysis of the RNA expression level of thousands of genes accelerates the research in molecular biology and leads to new insights in signalling pathways. Furthermore, genomic gains or losses can be analyzed for complete genomes in a single experiment. This creates new opportunities for understanding distinct chromosomal changes in the development of cancer. The ability to genotype patients using single nucleotide polymorphisms is of primordial interest to the pharmaceutical industry and may result in a more individualized medicine. Tissue microarrays are very useful in the investigation of the expression of a particular gene in hundreds of specimens by in situ hybridization. Also, protein microarrays are currently being developed for studying protein-protein interactions. In conclusion, microarrays will revolutionize all aspects of molecular biology, and will probably have the same impact as the polymerase chain reaction.

Non-LTR retrotransposons with unique integration preferences downstream of Dictyostelium discoideum tRNA genes

Retrotransposable elements are genetic enti ties which move and replicate within host cell genomes We have previously reported on the structures and ge nomic distributions of two non-long terminal repea (non-LTR) retrotransposons, DRE and Tdd-3, in the eukaryotic microorganism Dictyostelium discoideum DRE elements are found inserted upstream, and Tdd-3 elements downstream, of transfer RNA (tRNA) genes with remarkable position and orientation specificities The data set currently available from the Dictyostelium Genome Project led to the characterisation of two repetitive DNA elements which are related to the D. discoideum non-LTR retrotransposon Tdd-3 in both their structural properties and genomic distributions. It appears from our data that in the D. discoideum genome tRNA genes are major targets for the insertion of mobilised non-LTR retrotransposons. This may be interpreted as the consequence of a process of coevolution, allowing a viable population of retroelements to transpose without being deleterious to the small microbial host genome which carries only short intergenic DNA sequences. A new nomenclature is introduced to designate all tRNA gene-targeted non-LTR retrotransposons (TREs) in the D. discoideum genome. TREs inserted 5' and 3' of tRNA genes are named TRE5 and TRE3, respectively. According to this nomenclature DRE and Tdd-3 are renamed TRE5-A and TRE3-A, respectively. The new retroelements described in this study are named TRE3-B (formerly RED) and TRE3-C.

Characterization of the human suppressor of fused, a negative regulator of the zinc-finger transcription factor Gli

Drosophila Suppressor of fused (Su(fu)) encodes a novel 468-amino-acid cytoplasmic protein which, by genetic analysis, functions as a negative regulator of the Hedgehog segment polarity pathway. Here we describe the primary structure, tissue distribution, biochemical and functional analyses of a human Su(fu) (hSu(fu)). Two alternatively spliced isoforms of hSu(fu) were identified, predicting proteins of 433 and 484 amino acids, with a calculated molecular mass of 48 and 54 kDa, respectively. The two proteins differ only by the inclusion or exclusion of a 52-amino-acid extension at the carboxy terminus. Both isoforms were expressed in multiple embryonic and adult tissues, and exhibited a developmental profile consistent with a role in Hedgehog signaling. The hSu(fu) contains a high-scoring PEST-domain, and exhibits an overall 37% sequence identity (63% similarity) with the Drosophila protein and 97% sequence identity with the mouse Su(fu). The hSu(fu) locus mapped to chromosome 10q24-q25, a region which is deleted in glioblastomas, prostate cancer, malignant melanoma and endometrial cancer. HSu(fu) was found to repress activity of the zinc-finger transcription factor Gli, which mediates Hedgehog signaling in vertebrates, and to physically interact with Gli, Gli2 and Gli3 as well as with Slimb, an F-box containing protein which, in the fly, suppresses the Hedgehog response, in part by stimulating the degradation of the fly Gli homologue. Coexpression of Slimb with Su(fu) potentiated the Su(fu)-mediated repression of Gli. Taken together, our data provide biochemical and functional evidence for the hypothesis that Su(fu) is a key negative regulator in the vertebrate Hedgehog signaling pathway. The data further suggest that Su(fu) can act by binding to Gli and inhibiting Gli-mediated transactivation as well as by serving as an adaptor protein, which links Gli to the Slimb-dependent proteasomal degradation pathway.

Hedgehog signal transduction: from flies to vertebrates

The patterning and morphogenesis of multicellular organisms require a complex interplay of inductive signals which control proliferation, growth arrest, and differentiation of different cell types. A number of such signaling molecules have been identified in vertebrates and invertebrates. The molecular dissection of these pathways demonstrated that in vertebrates, mutations or abnormals function of these signaling pathways were often associated with developmental disorders and cancer formation. The Hedgehog (Hh) family of secreted proteins provides a perfect example of such signaling proteins. In the following review, we will not discuss in detail the role of Hh as a morphogen, but rather focus on its signal transduction pathway and its role in various human disorders.