Biomedical subjects

Genomics

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PubMed2025

Genome reorganisation and expansion shape 3D genome architecture and define a distinct regulatory landscape in coleoid cephalopods.

How genomic changes translate into organismal novelties is often confounded by the multi-layered nature of genome architecture and the long evolutionary timescales over which molecular changes accumulate. Coleoid cephalopods (squid, cuttlefish, and octopus) provide a unique system to study these processes due to a large-scale chromosomal rearrangement in the coleoid ancestor that resulted in highly modified karyotypes, followed by lineage-specific fusions, translocations, and repeat expansions. How these events have shaped gene regulatory patterns underlying the evolution of coleoid innovations, including their large and elaborately structured nervous systems, novel organs, and complex behaviours, remains poorly understood. To address this, we integrate Micro-C, RNA-seq, and ATAC-seq across multiple coleoid species, developmental stages, and tissues. We find that while topological compartments are broadly conserved, hundreds of chromatin loops are species- and context-specific, with distinct regulation signatures and dynamic expression profiles. CRISPR-Cas9 knockout of a putative regulatory sequence within a conserved region demonstrates the role of loops in neural development and the prevalence of long-range, inter-compartmental interactions. We propose that differential evolutionary constraints across the coleoid 3D genome allow macroevolutionary processes to shape genome topology in distinct ways, facilitating the emergence of novel regulatory entanglements and ultimately contributing to the evolution and maintenance of complex traits in coleoids.

Journal Article↗

PubMed1981

Reexamination of the genome size of myxobacteria, including the use of a new method for genome size analysis.

The genome sizes of two myxobacteria, Myxococcus xanthus and Stigmatella aurantiaca, were measured by renaturation analysis and also by a new method involving the quantitation of individual restriction fragments. In contrast to several previous reports, which indicate that M. xanthus has a genome size which is three to four times that of Escherichia coli, the present measurements indicated that the M. xanthus genome is only about 24 to 53% larger than that of E. coli. S. aurantiaca had a genome size nearly identical to that of M. xanthus. Of possible significance is the fact that the renaturation curves of M. xanthus and S. aurantiaca deoxyribonucleic acid both exhibited significant fractions which renatured with rapid, unimolecular kinetics. However, we were unable to establish that these fractions represented inverted repeats of repetitive sequences.

Chromosomes, Bacterial↗

PubMed1986

Human cardiac myosin heavy chain genes. Isolation of a genomic DNA clone and its characterization and of a second unique clone also present in the human genome.

A gene sequence coding for myosin heavy chain (MHC) of human cardiac muscle was isolated by screening a human genomic library with a 32P-labelled 1.1kb SacI restriction fragment from a previously characterized cDNA clone specifying the light meromyosin and 3' untranslated region of mRNA encoding rabbit cardiac alpha-MHC. The DNA of this human genomic clone (lambda HCMHC8) hybridized much more strongly than did other clones isolated under similar, low stringency conditions both to the rabbit cDNA probe and to mRNA isolated from rat cardiac, but not skeletal, muscle tissue. Probe made from a DNA restriction fragment of lambda HCMHC8 hybridized a single 31S band of human ventricular mRNA. This size is identical to that of cardiac MHC mRNA of other species. Heteroduplex analysis showed hybridization of lambda HCMHC8 with exon segments in a rabbit cardiac MHC genomic clone (lambda MHC alpha 12/1). It also showed that lambda HCMHC8 spanned 14 kb of DNA and contained exon segments estimated to code for two-thirds of a MHC including the carboxylic acid terminus. By rescreening the library under more stringent conditions, where only DNA sequences having strong homology to cardiac MHC genes would be expected to hybridize, clones having restriction maps overlapping lambda HCMHC8 were isolated together with a unique clone (lambda HCMHC9). DNA gel blot hybridization of human genomic DNA with lambda HCMHC8 probe at medium stringency gave a pattern of restriction fragments similar to the restriction map of lambda HCMHC8. A weaker set of bands also appeared which corresponded in pattern to the map of lambda HCMHC9.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

The difference in tumorigenicity between Epstein-Barr virus (EBV) genome-positive and genome-negative epithelial hybrid cell lines derived from the human nasopharynx.

An epithelial/hybrid cell line was previously established (A2L/AH) by the fusion of 8-azaguanine-resistant epithelial cells (Ad-AH) with Epstein-Barr virus (EBV)-transformed lymphoblastoid cells (A2L), as a nasopharyngeal carcinoma (NPC) model cell line in vitro. However, the A2L/AH cells were nontumorigenic in nude mice during early passage levels. In this study, an EBV genome-negative clone and two EBV genome-positive clones of the A2L/AH cells have been successfully cloned. We have continued to culture these three clones, as it is possible that EBV may disturb mechanisms that regulate tumorigenicity when cells are grown in vitro for long periods of time. Two EBV genome-positive A2L/AH clones have become tumorigenic in nude mice after long periods in culture, whereas EBV genome-negative A2L/AH cells were nontumorigenic after the same period of time. The data suggest that EBV may be associated with tumorigenicity in nude mice, at least in part.

Animals↗

PubMed2026

Complete mitochondrial genomes of eight cyclophyllidean tapeworms: genome pattern and phylogenetic analysis.

Cyclophyllidean tapeworms are widespread parasites of significant medical and veterinary importance. However, mitochondrial (mt) genomic resources for cyclophyllideans from China, particularly those recovered from wildlife hosts, remain comparatively limited. In this study, we sequenced and characterized the complete mt genomes of eight cyclophyllidean isolates collected from diverse wild and domestic hosts in China, including two Hymenolepis sp. isolates and two Raillietina sp. isolates from China, and four additional isolates of previously sequenced Taenia species. The circular mt genomes ranged from 13,387 to 14,021 bp in length, encoding 36 typical genes with variable non-coding regions. Comparative analysis revealed highly conserved gene composition and mostly conserved mt architecture, with localized rearrangement patterns detected among the cyclophyllidean lineages examined. In particular, all sampled Taeniidae exhibited a consistent trnL1-trnS2 arrangement, whereas the examined non-Taeniidae families showed the trnS2-trnL1 arrangement, confirming and extending, across additional wildlife-associated isolates, a previously proposed family-associated gene-order marker within Cyclophyllidea. Phylogenetic analyses based on concatenated amino acid sequences of the 12 protein-coding genes placed the eight isolates within their expected families, in topologies broadly consistent with previous mitogenomic studies. These data provide additional Chinese mitogenomic references, especially for underrepresented wildlife-associated isolates, and support family-associated gene-order patterns in Cyclophyllidea.

Animals↗

PubMed2025

The T2T genome assembly of watershield (Brasenia schreberi) unveils genomic insights into aquatic adaptation.

Watershield (Brasenia schreberi), belonging to Cabombaceae within the order Nymphaeales, represents one of the early-diverged angiosperm lineages. This perennial floating leaf freshwater aquatic plant features submerged juvenile leaves enveloped in a thick layer of transparent gelatinous mucilage, aiding in its resistance to aquatic stress. However, the evolutionary history of the mechanisms underlying its specific phenotype remains unclear. In this study, we present the telomere-to-telomere level genome of B. schreberi, unveiling that it underwent two rounds of whole-genome duplications (WGDs) and a recent whole-genome triplication, with the most ancient WGD being shared by Nymphaeaceae. WGD and dispersed duplication significantly contributed to the expansion of gene families, which are primarily associated with environmental adaptation. Additionally, we discovered that mature leaves primarily conduct photosynthesis and may transport nutrients to underwater juvenile leaves for polysaccharide synthesis. We also identified an ancestral broad expression pattern of ABC genes, and the similar expression of anthocyanin biosynthesis genes across all flower organs resulted in entirely purple flowers. Our findings deepen the understanding of the evolution of this specific aquatic plant phenotypes.

Genome, Plant↗

PubMed2026

Pleomorphic Liposarcoma: Comprehensive Genomic Analysis of 39 Cases With Comparison to Other Genomically Complex Sarcomas.

Pleomorphic liposarcoma (PLPS) is an aggressive high-grade sarcoma that often shows diverse morphological features and can mimic high-grade undifferentiated pleomorphic sarcoma (UPS)/spindle cell sarcoma or myxofibrosarcoma (MFS), especially when pleomorphic lipoblasts are sparse. The molecular profile of PLPS is distinct from well differentiated/dedifferentiated liposarcoma and myxoid liposarcoma. In this study, we investigate 39 cases of PLPS by comprehensive genomic profiling, occurring in 32 patients with available molecular data. Cases were reviewed and morphologic parameters-lipoblastic component, UPS-like, and MFS-like areas were estimated. The genomic findings were collected and compared to UPS and MFS groups studied using the same platform. The cohort included 15 females and 17 males, with a median age of 56.5 (range, 34-78). The lower extremity (n = 17) was the most common site involved, followed by upper extremity (n = 5) and pelvis (n = 5). UPS-like and MFS-like patterns were the most common morphologic variants, ranging from 15% to 95% and 20% to 90%, respectively. TP53 (87%) and RB1 (51%) mutations and copy number alterations were the most common alterations seen, followed by ATRX (36%). Compared to UPS and MFS, TP53 and RB1 gene alterations were significantly more common in PLPS. Conversely, CDKN2A/B deletions were infrequent in PLPS. Survival analysis showed that MYC amplification was associated with significantly shorter overall survival in PLPS. Among histologic variants, CYSLTR2 alterations were found to be highest in cases with predominantly pleomorphic lipoblasts; additionally, strong correlations were found between gene alteration frequencies of MFS and MFS-like PLPS, and between UPS and UPS-like PLPS. RB1 allele-specific copy number analysis showed loss of heterozygosity in 82% of cases. Our cohort of PLPS showed a complex molecular landscape with distinct genetic alterations, histologic correlations, and clinical outcomes, highlighting its unique position among genomically complex sarcomas and providing insights that may inform future diagnostic and therapeutic approaches.

Humans↗

PubMed2025

Genome-scale evolution and phylodynamics of swine influenza A viruses in China: a genomic epidemiology study.

BACKGROUND: Pigs are recognised as crucial intermediate hosts for the emergence of influenza viruses of pandemic potential. As the largest pork-producing nation, China hosts a complex ecosystem of swine influenza viruses (SIVs). We aimed to investigate the evolutionary processes, spatiotemporal dynamics, and biological characteristics of SIVs in China. METHODS: From Jan 15, 2016, to Dec 22, 2020, we collected nasal swabs from pigs at eight abattoirs and 16 swine farms in the Guangdong, Henan, and Shandong provinces of China, as part of SIV surveillance. SIVs were detected with RT-PCR. Positive samples underwent viral isolation and genome sequencing. We analysed evolution and spatiotemporal dynamics using the whole genomes of isolated SIVs, as well as genome sequences of SIV isolates from human infections worldwide retrieved from the Global Initiative on Sharing All Influenza Data and GenBank Flu databases up to April 28, 2024. Viral sequences without a sample collection area or date were excluded from the analysis. Viral receptor-binding properties and in-vitro replication of strains isolated in this study were evaluated with a solid-phase binding assay and various cell lines, including Madin-Darby canine kidney cells, porcine alveolar macrophages, primary porcine trachea epithelial cells, human bronchial epithelioid, and human lung adenocarcinoma epithelial (A549) cells. Viral replication and transmission studies were conducted in 33 guinea pigs and 13 pigs. Additionally, we collected serum samples from pig farm workers and members of the general public recruited by the Third Affiliated Hospital of Sun Yat-sen University between Feb 28 and May 11, 2023, to detect specific antibodies against Eurasian avian-like A(H1) and human-like A(H3N2) SIVs using the haemagglutination inhibition assay. FINDINGS: 23 (1·3%) of 1818 nasal swabs collected in abattoirs had SIVs; 22 (0·9%) of 2375 swabs from swine farms had SIVs. Further viral isolation yielded 39 strains of SIV. We identified 534 A(H1N1), 69 A(H1N2), and 92 A(H3N2) SIVs, representing 20 genotypes within the Eurasian avian-like lineage, 14 within the classical swine A(H1) lineage, and 16 within the human-like A(H3N2) lineage. The introduction of the A(H1N1)pdm/09 virus significantly influenced the internal gene pool of SIVs, enhancing genotypic diversity in China. Notably, the Eurasian avian-like A(H1), classical swine A(H1), and human-like A(H3N2) lineages showed human-mediated spread over long distances between provinces, with the Eurasian avian-like A(H1) lineage showing the most prevalent spread pathways. Eurasian avian-like A(H1) SIVs showed a preference for binding to sialic acid α-2,6 glycan receptors, predominantly found in humans, resulting in an increased production of progeny viruses in human airway epithelial cells, as well as effective transmission and infectivity among guinea pigs and pigs. Among 54 eligible serum samples collected from pig farm workers (24 from slaughterhouses and 30 from swine farms), 23 (43%) were seropositive for Eurasian avian-like A(H1) SIVs and 46 (85%) for human-like A(H3N2) SIVs. Among 100 eligible samples from members of the general public, 14 (14%) were seropositive for Eurasian avian-like A(H1) SIVs and 85 (85%) for human-like A(H3N2) SIVs. INTERPRETATION: This study elucidates the evolutionary processes and spatiotemporal patterns of SIVs, highlighting potential risks to public health. These findings are crucial for informing public health interventions that aim to prevent future SIV epidemics in China and other countries worldwide. FUNDING: Scientific Innovation Strategy-Construction of High-Level Academy of Agriculture Science-Distinguished Scholar (R2020PY-JC001).

Animals↗

PubMed2025

Efficacy of EGFR tyrosine kinase inhibitors in patients with non-small cell lung cancer with EGFR exon 19 insertions: clinical-genomic, preclinical analysis through LC-SCRUM-Asia (multi-institutional genomic screening registry).

BACKGROUND: EGFR exon 19 insertions (EGFRex19ins) are rare EGFR mutations. Their clinical-genomic characteristics and outcomes with EGFR-tyrosine kinase inhibitors (TKIs) remain uncertain. METHODS: We evaluated the clinical-genomic characteristics and outcomes of EGFR-TKIs for EGFRex19ins in the multi-institutional prospective lung cancer genomic screening project (LC-SCRUM-Asia). We also studied preclinical Ba/F3 models expressing EGFR-K745_E746insIPVAIK (Ba/F3-IPVAIK) to investigate their sensitivity to 1st-, 2nd-, 3rd-generation, and EGFR exon 20 insertion-active TKIs. RESULTS: In LC-SCRUM-Asia, 16,204 NSCLC patients were enrolled from March 2015 to December 2023. EGFRex19ins were detected in 13 samples (0.1 % of NSCLC). The median age was 72 years (range, 38-80); most patients were female (77 %), had adenocarcinoma (92 %), and were never-smokers (62 %). Twelve patients (93 %) had EGFR-K745_E746insIPVAIK, while one (7 %) had EGFR-K745_E746insVPVAIK. The most frequent co-mutation was TP53 (62 %); no patients had other driver alterations. Six patients (46 %) tested positive for EGFR exon 19 deletions with PCR-based Cobas EGFR test, likely due to cross-reactivity arising from sequence homology. Twelve patients received EGFR-TKIs; five (42 %) experienced partial response. In the preclinical study, Ba/F3-IPVAIK showed the highest sensitivity to 2nd-generation EGFR-TKIs compared to other EGFR-TKIs. Structural studies supported these consistent results. When broken down by EGFR-TKI generations, response rates for 1st-, 2nd-, and 3rd-generation TKIs were 50 % (1/2), 80 % (4/5), and 0 % (0/5), respectively. The median PFS for 1st-, 2nd-, and 3rd-generation TKIs were 8.7 (95 % CI, 7.4-NR), 14.7 (95 % CI, 8.0-NR), and 4.4 (95 % CI, 3.4-NR) months, respectively. CONCLUSION: Our preclinical, structural, and clinical findings indicate 2nd-generation EGFR-TKIs are more effective for EGFRex19ins compared to other TKIs.

Adult↗

PubMed1992

The herpes simplex virus type 1 (HSV-1) a sequence serves as a cleavage/packaging signal but does not drive recombinational genome isomerization when it is inserted into the HSV-2 genome.

We inserted the terminal repeat (a sequence) of herpes simplex virus type 1 (HSV-1) strain KOS into the tk gene of HSV-2 strain HG52 in order to assess the ability of the HSV-1 a sequence to provoke genome isomerization events in an HSV-2 background. We found that the HSV-1 a sequence was cleaved by the HSV-2 cleavage/packaging machinery to give rise to novel genomic termini. However, the HSV-1 a sequence did not detectably recombine with the HSV-2 a sequence. These results demonstrate that the viral DNA cleavage/packaging system contributes to a subset of genome isomerization events and indicate that the additional recombinational inversion events that occur during infection require sequence homology between the recombination partners.

Base Sequence↗

PubMed2025

SIGEL: a context-aware genomic representation learning framework for spatial genomics analysis.

Spatial transcriptomics (ST) integrates spatial information into genomics, yet methods for generating spatially-informed gene representations are limited and computationally intensive. We present SIGEL, a cost-effective framework that derives gene manifolds from ST data by exploiting spatial genomic context. The resulting SIGEL-generated gene representations (SGRs) are context-aware, biologically meaningful, and robust across samples, making them highly effective for key downstream tasks, including imputing missing genes, detecting spatial expression patterns, identifying disease-related genes and interactions, and improving spatial clustering. Extensive experiments across diverse ST datasets validate SIGEL's effectiveness and highlight its potential in advancing spatial genomics research.

Genomics↗

PubMed2025

Evaluating the return of additional findings from the 100,000 Genomes Project: A mixed-methods study exploring participant experiences of receiving secondary findings from genomic sequencing.

PURPOSE: The 100,000 Genomes Project participants could consent to receive additional findings (AFs) for variants associated with susceptibility to cancer and familial hypercholesterolemia. Here, we evaluate stakeholder experiences to inform clinical practice. METHODS: Mixed-methods study conducted at 18 sites across England that comprised a cross-sectional survey and interviews with participants who received a positive AF (PAF) and interviews with participants who had no AFs (NAF). RESULTS: There were 146 surveys followed by 35 interviews with PAF participants and 29 interviews with NAF participants. Surveys found that PAF results were seen as useful and would influence health management (82%). Most (90%) had shared their result with family members. Experiences differed by PAF type; cancer PAF participants were often initially shocked and anxious and found telling family members challenging compared with participants with a familial hypercholesterolemia PAF. Although most experiences of NAF results were positive, some misunderstandings were identified. Participants supported returning AFs when offering genome sequencing. CONCLUSION: Patient experiences of receiving AFs were primarily positive, and there is support for offering AFs routinely. Considerations for offering AFs in clinical practice include adapting approaches tailored to individual conditions and greater support for people with a NAF result.

Humans↗

PubMed2026

Analyzing salinity tolerance in grass carp (Ctenopharyngodon idella): Insights from genome-wide association study and genomic selection.

Grass carp (Ctenopharyngodon idella) is one of the most widely cultured freshwater fish species globally. However, the expansion of its farming scale faces severe limitation owing to freshwater scarcity; therefore, the development of strains with greater salinity tolerance is key for expanding production using brackish water resources. To investigate the genetic basis of salinity tolerance in grass carp, a genome-wide association study (GWAS) was conducted using 200 individuals representing extreme phenotypes, namely salinity-tolerant and salinity-sensitive groups. In total, 17 single nucleotide polymorphisms (SNPs) related to salinity tolerance were detected, which were distributed across 11 chromosomes. Through gene annotation, 38 candidate genes were obtained from these loci. Enrichment analysis revealed these candidate genes are primarily implicated in key biological processes, including osmotic regulation, energy metabolism, and stress responses. Analyses of different SNP densities revealed that the 5 K SNP density panel can balance prediction accuracy and computational efficiency. The BayesA model achieved the highest prediction accuracy under the GWAS_Evenly selection strategy, with substantial reductions in mean absolute error and mean square error. This study reveals the genetic mechanisms of salinity tolerance in grass carp, which might be optimized through genomic selection, and provides insights for selectively breeding new varieties with greater salinity tolerance.

Animals↗

PubMed1991

The male-derived genome after sperm-egg fusion: spatial distribution of chromosomal DNA and paternal-maternal genomic association.

After fusion with an egg, the haploid genome of a mammalian sperm expands from a volume of a few cubic microns to a volume of several thousand cubic microns in a fully developed zygote pronucleus. Using fluorescent in situ hybridization we studied two aspects of the chromatin organization of the sperm-derived genome during this process in a model system involving fusion of human sperm with hamster eggs. We found that (a) from the beginning of sperm head decondensation to early pronuclear stages, the hybridization signal of a probe targeted to the satellite III heterochromatin of chromosome 1 appeared as an irregularly shaped domain. In fully developed pronuclei, the signal became a fiber as much as 20-fold more extended compared with interphase somatic nuclei. The signal appeared as a string of non-uniformly distributed "beads" with interspersed gaps. A similar spatial distribution and appearance recurred after the first cleavage division. (b) Male- and female-derived genomes assembled non-randomly on the first mitotic spindle, and continued to be sequestered from each other in the nuclei of two-cell stages.

Animals↗

PubMed1984

The mitochondrial genome of the fission yeast Schizosaccharomyces pombe. 2. Localization of genes by interspecific hybridization in strain ade7-50h- and cloning of the genome in small fragments.

A series of 18 small overlapping restriction fragments has been cloned, covering the complete mitochondrial genome of Schizosaccharomyces pombe. By hybridizing mitochondrial gene probes from Saccharomyces cerevisiae and Neurospora crassa with restriction fragments of Schizosaccharomyces pombe mitochondrial DNA, the following homologous genes were localized on the mitochondrial genome of S. pombe: cob, cox1, cox2 and cox3, ATPase subunit 6 and 9 genes, the large rRNA gene and both types of open reading frames occurring in mitochondrial introns of various ascomycetes. The region of the genome, hybridizing with cob exon probes is separated by an intervening sequence of about 2500 bp, which is homologous with the first two introns of the cox1 gene in Saccharomyces cerevisiae (class II introns according to Michel et al. 1982). Similarly, in the cox1 homologous region, which covers about 4000 bp, two regions were detected hybridizing with class I intron probes, suggesting the existence of two cox1 introns in Schizosaccharomyces pombe. Hybridization with several specific exon probes with a determined order has revealed that cob, cox1, cox3 and the large rRNA gene are all transcribed from the same DNA strand. The low intensities of hybridization signals suggest a large evolutionary distance between Schizosaccharomyces pombe and Saccharomyces cerevisiae or Neurospora crassa mitochondrial genes. Considering the length of the mitochondrial DNA of Schizosaccharomyces pombe (about 19.4 kbp) and the expected length of the localized genes and intron sequences there is enough space left for encoding the expected set of tRNAs and the small rRNA gene. The existence of leader-, trailer-, ori- and spacer sequences or further unassigned reading frames is then restricted to a total length of about 3000 bp only.

Ascomycota↗

PubMed1985

Nucleotide sequence and genetic organization of the genome of the N-specific filamentous bacteriophage IKe. Comparison with the genome of the F-specific filamentous phages M13, fd and f1.

The nucleotide sequence and genetic organization of the genome of the N-specific filamentous single-stranded DNA phage IKe has been established and compared with that of the F-specific filamentous phages M13, fd and f1 (Ff). The IKe DNA sequence comprises 6883 nucleotides, which is 476 (475) nucleotides more than the nucleotide sequence of the Ff genome. The data indicate that IKe and Ff have evolved from a common ancestor (overall homology approx. 55%) and that their genomes contain ten homologous genes, the order of which is identical. Similar to Ff, the major coat protein and the gene III-encoded pilot protein of IKe are synthesized via precursor molecules. The extent of homology between the genes of IKe and Ff differs significantly from one gene to another. Genes that code for viral capsid proteins are less homologous than genes whose products are involved in the processes of DNA replication and phage morphogenesis. During evolution, large nucleotide sequence rearrangements have occurred in the gene (gene III) whose product is needed for the attachment of the virion to the conjugative pili of the host cell, suggesting that these rearrangements have led to phages with different host specificities. Extensive nucleotide sequence homology was noted between the structural elements involved in DNA replication and phage morphogenesis, indicating that the mechanisms involved in DNA replication and morphogenesis are highly conserved.

Base Sequence↗

PubMed1987

Tumorigenic poxviruses: genomic organization and DNA sequence of the telomeric region of the Shope fibroma virus genome.

Shope fibroma virus (SFV), a tumorigenic poxvirus, has a 160-kb linear double-stranded DNA genome and possesses terminal inverted repeats (TIRs) of 12.4 kb. The DNA sequence of the terminal 5.5 kb of the viral genome is presented and together with previously published sequences completes the entire sequence of the SFV TIR. The terminal 400-bp region contains no major open reading frames (ORFs) but does possess five related imperfect palindromes. The remaining 5.1 kb of the sequence contains seven tightly clustered and tandemly oriented ORFs, four larger than 100 amino acids in length (T1, T2, T4, and T5) and three smaller ORFs (T3A, T3B, and T3C). All are transcribed toward the viral hairpin and almost all possess the consensus sequence TTTTTNT near their 3' ends which has been implicated for the transcription termination of vaccinia virus early genes. Searches of the published DNA database revealed no sequences with significant homology with this region of the SFV genome but when the protein database was searched with the translation products of ORFs T1-T5 it was found that the N-terminus of the putative T4 polypeptide is closely related to the signal sequence of the hemagglutinin precursor from influenza A virus, suggesting that the T4 polypeptide may be secreted from SFV-infected cells. Examination of other SFV ORFs shows that T1 and T2 also possess signal-like hydrophobic amino acid stretches close to their N-termini. The protein database search also revealed that the putative T2 protein has significant homology to the insulin family of polypeptides. In terms of sequence repetitions, seven tandemly repeated copies of the hexanucleotide ATTGTT and three flanking regions of dyad symmetry were detected, all in ORF T3C. A search for palindromic sequences also revealed two clusters, one in ORF T3A/B and a second in ORF T2. ORF T2 harbors five short sequence domains, each of which consists of a 6-bp short palindrome and a 10- to 18-bp larger palindrome. The significance of these palindromic domains in this ORF is unclear but the coincidence of the end of one larger palindrome with the end of the translated protein sequence that has homology with the B chain of insulin suggests that the palindromes may divide the T2 protein into several functional units. The salient organizational features of the complete SFV TIR are also discussed in light of what is known about other poxviral TIRs.

Amino Acid Sequence↗

PubMed1979

Genome analysis of Amphioxus and speculation as to the origin of contrasting vertebrate genome organization patterns.

1. The genome of Amphioxus was investigated by DNA reassociation techniques for the amount of repetitive and non-repetitive sequences and its pattern of organization. 2. A comparison of the amount of non-repetitive DNA between Amphioxus and the tunicate Ciona intestinalis does not support the hypothesis that the Cephalochordates have arisen from the Tunicates by polyploidy. 3. In the Amphioxus genome repetitive and non-repetitive elements are predominantly arranged in a short period interspersion pattern. Conclusions are presented as to the evolution of contrasting genome organization patterns among vertebrates.

Animals↗