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PubMed2006

Piloting the zebrafish genome browser.

This correspondence is a primer for the zebrafish research community on zebrafish tracks available in the UCSC Genome Browser at http://genome.ucsc.edu based on Sanger's Zv4 assembly. A primary capability of this facility is comparative informatics between humans (as well as many other model organisms) and zebrafish. The zebrafish genome sequencing project has played important roles in mutant mapping and cloning, and comparative genomic research projects. This easy-to-use genome browser aims to display and download useful genome sequence information for zebrafish mutant mapping and cloning projects. Its user-friendly interface expedites annotation of the zebrafish genome sequence.

Animals↗

PubMed2026

DNA Extraction Optimisation for Minute Land Snails of Vertigo Müller, 1773 (Gastropoda: Vertiginidae): A Comparative Evaluation of Six Methods, Including a Non-Destructive Shell-Preserving Protocol.

No systematic comparison of DNA extraction strategies exists for minute Vertiginidae (shell height < 3 mm), a group posing a dual analytical challenge: extremely low tissue input and co-purified PCR-inhibitory mucus. For legally protected species, an additional requirement to preserve the shell voucher further constrains available protocols. Using Vertigo antivertigo as the model species, we compared six approaches applied to specimens preserved in 96% ethanol (n = 10 per method): two HotSHOT alkaline-lysis protocols (destructive and non-destructive shell-preserving variants), a modified CTAB protocol supplemented with PVP-40 and DTT, and three commercial silica-column kits (GeneJET Genomic, DNeasy Blood & Tissue, QIAamp DNA Micro). DNA yields were quantified by QuantiFluor fluorometry, and PCR performance was subsequently assessed across four loci (COI barcode, COI mini-barcode, ITS1, ITS2). DNeasy Blood & Tissue produced the highest fluorometric concentrations; QIAamp DNA Micro and CTAB + PVP-40 gave intermediate values. The shell-preserving HotSHOT variant yielded lower concentrations but improved A260/230 ratios. BSA and trehalose supplementation increased PCR success in inhibition-prone HotSHOT extracts from 70% to 100%. ITS1 Sanger sequencing of three Vertigo species listed in Annex II of the EU Habitats Directive, all extracted with the shell-preserving protocol, confirmed species-level identification (99.8%-100% BLASTn identity; mean Phred Q > 51). The shell-preserving non-destructive HotSHOT protocol yields sequenceable DNA from protected Vertiginidae while retaining the morphological voucher, making it the preferred option for conservation-genetic monitoring. The practical decision framework documented here-integrating voucher preservation, amplification robustness and per-sample cost-has broad applicability to other minute terrestrial gastropods processed in large-scale biodiversity surveys.

Habitats Directive↗

PubMed1997

DNA sequencing with pulsed-field capillary electrophoresis in poly(ethylene oxide) matrix.

DNA sequencing by using pulsed-field capillary electrophoresis in a linear polymer matrix was performed in this work. The effects of waveform, frequency, modulation depth and heating were investigated. The separation performance for Sanger DNA fragments up to 1000 bp using a pulsed field was compared to isoelectric and isorheic conditions. A separation mechanism in the flexible poly(ethylene oxide) (PEO) gel was also suggested. We found that temperature change generated by either a pulsed field or ultrasound during DNA sequencing can have a deleterious effect on the separation efficiency.

Electrophoresis, Capillary↗

PubMed1997

Electrophoresis of DNA sequencing fragments at elevated temperature in capillaries filled with poly(N-acryloylaminopropanol) gels.

The performance of poly(N-acryloylaminopropanol) (poly AAP) gel columns, proved to be stable during electrophoresis at elevated temperature, was investigated. The column manufacturing procedure included the preparation of a coating of the inner wall of the fused silica capillary column with linear poly(AAP). Then, a mixture of the AAP monomer, the cross-linker dihydroxyethylenebisacrylamide (DHEBA) and linear poly(AAP) was introduced into the column and in situ polymerized (for preparation of linear gel columns, the addition of DHEBA was omitted). The poly(AAP) columns were first evaluated by electrophoresis of oligonucleotides at room temperature and at 50 degrees C, utilizing 260 nm UV-absorbance detection. In a further evaluation of column performance, samples of T-terminated DNA Sanger fragments from the bacteria Moraxella were separated at 200 V/cm electrical field strength, utilizing a 488 nm argon ion laser and a confocal optical setup for laser-induced fluorescence (LIF) detection. A temperature increase from 25 degrees C to 50 degrees C effectively released a compression of DNA bands. However, for cross-linked poly(AAP) gel columns, the elevated temperature resulted in a considerable reduction of the DNA sequence reading length. When a linear poly(AAP) column was utilized, no detrimental effect of elevated temperature on the separation could be observed.

Acrylic Resins↗

PubMed2003

Multiple-primer DNA sequencing method.

A multiple-primer DNA sequencing approach suitable for genotyping, detection and identification of microorganisms and viruses has been developed. In this new method two or more sequencing primers, combined in a pool, are added to a DNA sample of interest. The oligonucleotide that hybridizes to the DNA sample will function as a primer during the subsequent DNA sequencing procedure. This strategy is suited for selective detection and genotyping of relevant microorganisms and samples harboring different DNA targets such as multiple variant/infected samples as well as unspecific amplification products. This method is used here in a model system for detection and typing of high-risk oncogenic human papilloma viruses (HPVs) in samples containing multiple infections/variants or unspecific amplification products. Type-specific sequencing primers were designed for four of the most oncogenic (high-risk) HPV types (HPV-16, HPV-18, HPV-33, and HPV-45). The primers were combined and added to a sample containing a mixture of one high-risk (16, 18, 33, or 45) and one or two low-risk types. The DNA samples were sequenced by the Pyrosequencing technology and the Sanger dideoxy sequencing method. Correct genotyping was achieved in all tested combinations. This multiple-sequencing primer approach also improved the sequence data quality for samples containing unspecific amplification products. The new strategy is highly suitable for diagnostic typing of relevant species/genotypes of microorganisms.

DNA Primers↗

PubMed2006

What is the future of electrophoresis in large-scale genomic sequencing?

Although a finished human genome reference sequence is now available, the ability to sequence large, complex genomes remains critically important for researchers in the biological sciences, and in particular, continued human genomic sequence determination will ultimately help to realize the promise of medical care tailored to an individual's unique genetic identity. Many new technologies are being developed to decrease the costs and to dramatically increase the data acquisition rate of such sequencing projects. These new sequencing approaches include Sanger reaction-based technologies that have electrophoresis as the final separation step as well as those that use completely novel, nonelectrophoretic methods to generate sequence data. In this review, we discuss the various advances in sequencing technologies and evaluate the current limitations of novel methods that currently preclude their complete acceptance in large-scale sequencing projects. Our primary goal is to analyze and predict the continuing role of electrophoresis in large-scale DNA sequencing, both in the near and longer term.

Animals↗

PubMed2025

Coronavirus Cryptic Landscape and Draft Genome of a Novel CoV Clade Related to MERS From Bats Circulating in Northeastern Brazil.

We identified seven distinct coronaviruses (CoVs) in bats from Brazil, classified into 229E-related (Alpha-CoV), Nobecovirus, Sarbecovirus, and Merbecovirus (Beta-CoV), including one closely related to MERS-like CoV with 82.8% genome coverage. To accomplish this, we screened 423 oral and rectal swabs from 16 different bat species using molecular assays, RNA sequencing, and evolutionary analysis. Notably, gaps in the spike-encoding gene led us to design new primers and perform Sanger sequencing, which revealed high similarities to MERS-related (MERSr) CoV strains found in humans and camels. Additionally, we identified key residues in the receptor-binding domain (RBD) of the spike protein, suggesting potential interactions with DPP4, the receptor for MERSr-CoV. Our analyses also revealed evidence of recombination involving our laboratory-produced sequences. These findings highlight the extensive genetic diversity of CoVs, the presence of novel viral lineages, and the occurrence of recombination events among bat CoVs circulating in Brazil, underscoring the critical role bats play as reservoirs for emerging viruses and emphasizing the necessity of ongoing surveillance to monitor the public health risks associated with CoV spillover events.

Chiroptera↗

PubMed2025

Clinical Impact and Genetic Analysis of Enteric Viruses Associated With Acute Gastroenteritis in Greater Accra, Ghana: A Comprehensive Study of Five Viruses.

Enteric viruses are significantly associated with acute gastroenteritis globally. Despite a decrease in severe rotavirus associated diarrhoea, Ghana still records high diarrhoea burden. Meanwhile aetiological investigations in hospital settings do not routinely include viral testing. Rotavirus vaccination is thought to alter enteric viral populations and impact evolution. To better understand virus-specific effects in acute gastroenteritis in both children and adults, we tested fecal samples from 228 patients at two hospitals in Accra from January to December 2019, using multiplex and singleplex PCR assays. The clinical impact of detected viruses was assessed using a modified Vesikari score system. Partial viral genome sequences were obtained by Sanger Sequencing and their genetic diversity and evolutionary history, traced by phylogenetic analyses. At least one enteric virus was found in 86 (37.7%) patient samples, with 36.9% of the population under five infected. Single infections of rotavirus, norovirus, adenovirus, sapovirus and astrovirus were 33, 14, 8, 6, and 1, respectively, while coinfections were 24. Rotavirus accounted for 33.3% of 24 clinically severe cases (modified Vesikari score > 7). Three out of 10 rotavirus cases with evidence of vaccination experienced severe gastroenteritis. Diverse genotypes, including RVA G2P[4], G1P[8], G12P[8] and G12P[6]; AdV F40 and F41; NoV GII.4 Sydney 2012, GII.6 and GI.3, several of which clustered with contemporary strains from the Americas, Europe and Asia, were detected. This study also provides the first report of SaV GI.1, GI.7 and GII.8 detection in humans in Ghana. RVA G2P[4] and AdV F were associated with higher proportions of hospitalizations. While RVA continues to have a profound clinical impact on gastroenteritis, AdV and SaV produce an equally severe disease. In contrast, NoV and AstV showed a generally mild to moderate impact on clinical disease severity.

Humans↗

PubMed2025

Unraveling the Role of Mutations Outside the Basal Promoter and Precore Regions in the HBeAg-Negative Stage of Chronic Hepatitis B.

Hepatitis B e antigen (HBeAg) seroconversion is a crucial event in the natural history of chronic hepatitis B virus (HBV) infection, marked by a significant decrease in viral load and the emergence of mutations that suppress HBeAg expression. However, these mutations alone do not fully account for the reduction in viral load. This study investigated the biological features and pathogenic roles of mutations outside the basal core promoter (BCP) and precore regions during the HBeAg-negative stage of chronic infection. Full-length HBV genomes from HBeAg-positive (n = 180) and HBeAg-negative (n = 328) genotype D datasets were analyzed, revealing significantly higher genomic heterogeneity in HBeAg-negative sequences compared with HBeAg-positive genomes (50.4 ± 16.0 vs. 26.6 ± 10.5 nucleotide changes per genome). Twenty-six hotspot amino acid mutations associated with the HBeAg-negative stage were identified, with over half located in the Core region. Subsequently, full-length HBV genomes from six HBeAg-negative patient-derived serum samples were obtained by PCR amplification followed by Sanger sequencing. Infectious clones generated from these genomes, each carrying between 21 and 66 amino acid substitutions, were characterized, showing that mutations in this stage differentially affected viral fitness in vitro by up- or downregulating HBV-DNA levels (ranging from 0.2 to 5 times those of the wild-type isolate), modulating capsid assembly, and altering the expression, secretion, and subcellular localization of viral proteins. In conclusion, while mutations in the BCP and precore regions are the primary drivers of HBeAg seroconversion, mutations outside these regions significantly influence HBV biology and potentially contribute to viral pathogenicity, underscoring the complex interplay between host and virus during the HBeAg-negative stage of chronic infection.

Humans↗

PubMed2025

Kaposi Sarcoma-Associated Herpesvirus Sequencing in People Living With HIV in the Southern United States Reveals Subtype Diversity and Multiple Infections.

Kaposi sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma and lymphoproliferative diseases collectively identified as KSHV-associated diseases (KAD). While KAD incidence has decreased across the United States, regional and population-based variability exists, with higher rates in southern states. To understand the molecular epidemiology of KSHV in this region, samples were collected from people living with HIV (PWH) with or without history of KAD. PWH, mainly men who have sex with men (MSM), were recruited from a large, urban hospital system in Dallas, Texas, in two separate studies. The studies included 220 individuals without KAD and 59 patients with KAD. Whole blood and/or oral fluids were collected and tested by qPCR. KSHV subtypes were determined from 66 of 85 individuals with detectable KSHV loads by a combination of next-generation and targeted Sanger sequencing. All major KSHV subtypes, except D, were observed including subtypes E and F. In each of three individuals, multiple KSHV genome variants were identified. This study importantly highlights KSHV subtype diversity in the southern United States, which is an area with a high KS incidence. Genome diversity and multiple infections merit epidemiological consideration, including for the future development of vaccines.

Humans↗

PubMed1984

Colorimetric determination of gentamicin, kanamycin, tobramycin, and amikacin aminoglycosides with 2,4-dinitrofluorobenzene.

The reaction of 2,4-dinitrofluorobenzene (Sanger's reagent) is used to form colored products with aminoglycoside antibiotics. Stopping the progress of the reaction with acid after a fixed time allows aqueous solubility to be maintained while discharging any color due to excess reactant. The choice of an appropriate analytical wavelength results in adherence to Beer's law. Although this colorimetric method is not expected to be stability-indicating, it is convenient and should be useful in content uniformity determinations for pharmaceutical dosage forms (e.g., ointments).

Amikacin↗

PubMed2004

Gene expression microarray analysis and genome databases facilitate the characterization of a chromosome 22 derived homogeneously staining region.

Karyotype and fluorescence in situ hybridization (FISH) analyses previously identified a homogeneously staining region (HSR) derived from chromosome 22 in OV90, an epithelial ovarian cancer (EOC) cell line. Affymetrix expression microarrays in combination with the UniGene and Human Genome Browser databases were used to identify the candidate genes comprising the amplicon of the HSR, based on comparison of expression profiles of OV90, EOC cell lines lacking HSRs and primary cultures of normal ovarian surface epithelial (NOSE) cells. A group of probe sets displaying a minimum 3-fold overexpression with a high reliability score (P-call) in OV90 were identified which represented genes that mapped within a 1-2 Mb interval on chromosome 22. A large number of probe sets, some of which represent the same genes, displayed no evidence of overexpression and/or low reliability scores (A-call). An investigation of the probe set sequences with the Affymetrix and Sanger Institute Chromosome 22 Group databases revealed that some of the probe sets displaying discordant results for the same gene were complementary to intronic sequences and/or the antisense strand. Microarray results were validated by RT-PCR. Genomic analysis suggests that the HSR was derived from the amplification of a 1.1 Mb interval defined by the chromosomal map positions of ZNF74 and Hs.372662, at 22q11.21. The deduced amplicon is derived from a complex region of chromosome 22 that harbors low-copy repeats (LCRs). The amplicon contains 18 genes as likely targets for gene amplification. This study illustrates that large-scale expression microarray analysis in combination with genome databases is sufficient for deducing target genes associated with amplicons and stresses the importance of investigating probe set design before engaging in validation studies.

Cell Line, Tumor↗

PubMed2026

Molecular Characterisation of Treacher Collins Syndrome in a South African Cohort: Novel Disease-Causing Variants in TCOF1 and POLR1D.

BACKGROUND: Treacher Collins syndrome (TCS) is a rare craniofacial disorder characterised by variable expressivity. It is caused by pathogenic variants in the TCOF1, POLR1D, POLR1C, or POLR1B genes. Common clinical features include hypoplasia of the zygomatic complex and mandible, downward-slanting palpebral fissures, lower eyelid anomalies, microtia, and hearing loss. Owing to its phenotypic overlap with other craniofacial syndromes, molecular testing is essential for establishing an accurate diagnosis and guiding effective clinical management. METHODS: Ten South African patients with a suspected clinical diagnosis of TCS underwent targeted next-generation sequencing (NGS) using a custom gene panel including TCOF1, POLR1C, and POLR1D genes. Variants were classified according to ACMG/AMP guidelines, with validation by Sanger sequencing where necessary. RESULTS: Disease-causing variants were identified in six of the ten patients (60%). These included five heterozygous variants in TCOF1 and one homozygous variant in POLR1D. Notably, five of the six variants were identified for the first time in this study. Additionally, a recurrent TCOF1 deletion was identified for the first time in an African family. CONCLUSION: This study expands the mutational spectrum of TCS in general and provides African data in particular. Findings support the use of panel-based NGS for diagnosis in resource-limited settings and highlight the need for population-specific variant data to improve diagnostic accuracy, guide clinical care, and support genetic counselling for affected individuals and their families.

Humans↗

PubMed2026

Novel TCOF1 Frameshift Variant and Phenotypic Heterogeneity in a Chinese Family With Treacher Collins Syndrome.

BACKGROUND: Treacher Collins syndrome (TCS) is a congenital craniofacial disorder characterized by malar and mandibular hypoplasia, downward-slanting palpebral fissures, and conductive hearing loss. Pathogenic variants in TCOF1 account for most cases, with POLR1D, POLR1C, and POLR1B also implicated. METHODS: Whole-exome sequencing was performed in a two-generation Chinese family with TCS, followed by Sanger sequencing validation. Clinical features were systematically evaluated, and bioinformatic analyses combined with structural modeling were employed to assess the potential pathogenicity of the identified variant. RESULTS: In this study, a novel heterozygous frameshift variant in TCOF1 (NM_001371623.1:c.1601_1602delCC, p.Pro534Leufs*15) was identified in the proband and his affected father. The proband presented classic TCS features including craniofacial skeletal hypoplasia, downward-slanting palpebral fissures, and conductive hearing loss. He also carried a right-sided preauricular fistula, a nonclassical feature of TCS. The same variant was detected in his affected father with a substantially milder phenotype, indicating marked intrafamilial phenotypic variability. Bioinformatic analysis and structural modeling predicted that this variant produces a severely truncated Treacle protein lacking key functional domains, which is predicted to disrupt nucleolar localization and ribosome biogenesis. CONCLUSION: Our findings expand the variant spectrum of TCOF1, highlight phenotypic heterogeneity in TCS, and reinforce the critical role of molecular diagnosis in distinguishing TCS from phenotypically overlapping craniofacial syndromes.

Humans↗

PubMed2026

Compound Heterozygous PCDH15 Variants Associated With Cone-Rod Dystrophy in a Chinese Pedigree.

BACKGROUND: This study aimed to characterize the clinical and genetic features of a Chinese family with cone-rod dystrophy in which compound heterozygous PCDH15 variants were identified. METHODS: A Chinese pedigree with autosomal recessive cone-rod dystrophy was investigated. A comprehensive ophthalmic assessment was performed in the proband, a 42-year-old woman, together with genetic evaluation of her family members. Candidate variants were identified using whole-exome sequencing and subsequently assessed by Sanger sequencing and family segregation analysis. RESULTS: Ophthalmoscopic examination revealed pigmentary changes and atrophic lesions affecting the posterior pole and peripapillary area bilaterally. Optical coherence tomography (OCT) demonstrated bilateral outer retinal layer atrophy with disruption of the ellipsoid zone at the posterior pole. Multifocal electroretinography (mfERG) revealed attenuated central responses, while full-field electroretinography (ffERG) documented a more pronounced reduction in cone-mediated (photopic) responses. Two novel compound heterozygous variants in PCDH15, namely c.4903_4906del (p.Glu1635Lysfs*4) and c.3470C>A (p.Ala1157Glu), were identified in this autosomal recessive cone-rod dystrophy pedigree. Family co-segregation analysis provided supportive evidence for their potential association with the disease phenotype. Cross-species analysis revealed high evolutionary conservation of the PCDH15 protein. Three-dimensional structural modeling predicted potential alterations in protein structure. CONCLUSION: To our knowledge, this is the first report describing an association between compound heterozygous PCDH15 variants and cone-rod dystrophy, thereby providing preliminary evidence that may broaden the mutational spectrum associated with this gene.

Adult↗

PubMed1997

Kaj Ulrik Linderstrøm-Lang (1896-1959).

The Carlsberg Laboratory in Copenhagen has had a long tradition of outstanding science. At the time covered by this discussion, Kjeldahl, Sørensen, and Linderstrøm-Lang had been consecutive directors of the Chemical Laboratory for 83 years. Lang's inspired leadership began in the 1930s with a number of innovations (study of metabolism in single cells, titrations in non-aqueous solvents, relation of proteolysis to structure) but it was not until the early 1950s that Denmark had sufficiently recovered from the war for the laboratory to enter world science again. During World War II, Lang had been active in the Danish resistance movement. After the war, a number of major advances were being made that would revolutionize the field of protein chemistry (Pauling and Corey's H-bonded structures, Sanger's sequencing techniques, chromatography, Watson and Crick structures, modern instrumentation). The time for the new field of the physical biochemistry of proteins had arrived. Lang, with his broad experience, adventurous spirit, and genius for innovation, created an environment that was ideal for the convergence of these disconnected advances into a uniform science. The emphasis was to be on quantitative measurements on proteins in solution with interpretations based on molecular structures. During an all-too-brief period of time, Lang's laboratory attracted a large fraction of those who were destined to be the leaders of the next generation of protein chemists. At this time, the Carlsberg Laboratory was probably the most scientifically exciting environment for a protein chemist. The methods developed at that time-hydrogen exchange, limited proteolysis, optical rotatory dispersion, volume changes accompanying protein reactions, automatic titrations-are still all in common use and many of the visitors to the laboratory in that period and their students are still playing major roles in protein research. Lang's other qualities should not be ignored. He was not only a great scientist but also a musician, raconteur, artist, and an exceptionally warm and compassionate human being.

Chemistry↗

PubMed2001

Genotyping single nucleotide polymorphisms using intact polymerase chain reaction products by electrospray quadrupole mass spectrometry.

Both single nucleotide polymorphisms (SNPs) and mutations are commonly observed in the gene encoding the tumor suppressor protein, p53. SNPs occur at specific locations within genes whereas mutations may be distributed across large regions of genes. When determining nucleotide differences, mass spectrometry is the only method other than Sanger sequencing which offers direct structural information. Electrospray ionization (ESI) quadrupole mass spectrometry (MS) analysis of intact polymerase chain reaction (PCR) products was performed following a simple purification and on-line heating to limit ion adduction. The PCR products were amplified directly from genomic DNA rather than plasmids, as in our previous work. Two known polymorphisms of the p53 gene were genotyped. A cytosine (C) or guanine (G) transversion, designated C <--> G (G <--> C on the opposite strand), were each detected by a 40.0 Da change upon ESI quadrupole MS analysis. Using known PCR products as standards, the genotypes determined for 10 human samples corresponded with restriction fragment length polymorphism (RFLP) analysis. Cytosine/thymine (T) transitions, designated C <--> T (G <--> A on the opposite strand), were also genotyped by ESI-MS. This SNP is discriminated by a 15.0 Da change on one strand (C <--> T) and a 16.0 Da change on the other (G <--> A). Appropriate sample preparation and instrumental configuration (including heated sample inlet syringe and MS source), to limit adducts, are both vital for successful ESI quadrupole MS analysis of intact PCR products.

DNA↗

PubMed1993

Method for sequencing synthetic oligodeoxynucleotide phosphorothioates.

Sequencing of oligodeoxynucleotide phosphorothioate by a modified Sanger method of sequencing is described. The procedure involves ligation of synthetic oligodeoxynucleotide phosphorothioate to an oligodeoxynucleotide, referred to here as "helper oligonucleotide." The helper oligonucleotide has a region which is complementary to T7 primer. By using DNA polymerase and nucleoside triphosphate mixture, 5'-labeled T7 primer is extended onto ligated oligodeoxynucleotide phosphorothioate, which is then analyzed on gel electrophoresis.

Base Sequence↗