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The snpA, a temperature-sensitive suppressor of npgA1, encodes the eukaryotic translation release factor, eRF1, in Aspergillus nidulans.

The npgA1 mutation causes defects in the outer layer of the cell wall resulting in a colorless colony. In this study, a temperature-sensitive suppressor of npgA1 named snpA was isolated by UV mutagenesis. The suppressing mutant showed pleiotropic phenotypes in cellular structure and developmental processes when incubated at a temperature of 37 degrees C or above. At 37 degrees C, multiple germ tubes emerged from germinating conidia. Moreover, at 42 degrees C conidia germination was delayed more than 12h and hyphal growth was strongly inhibited. The suppressor allele, snpA6, is recessive and maps to the linkage group III. A gene complementing the mutation was identified employing the chromosome III-specific cosmid library. Sequencing analysis revealed that the snpA gene encodes the eukaryotic polypeptide release factor, eRF1. The snpA6 allele contains a G-A mutation resulting in SnpA(E117K), which may allow read-through of the nonsense mutation in the npgA1 allele in a similar manner to the yeast omni-potent suppressor SUP45 and SUP35.

Amino Acid Sequence↗

Integrative dual-track transcriptomics reveals stage-specific coordination, regulatory divergence, and HSP90AA1-associated remodeling in human folliculogenesis.

Human folliculogenesis depends on coordinated yet non-identical developmental remodeling in the oocyte and its surrounding granulosa cells. When these two compartments remain synchronized and when they diverge into lineage-specific regulatory states, however, remains incompletely resolved. Here we performed an integrative dual-track re-analysis of the human RNA-seq dataset GSE107746, modeling oocytes and granulosa cells as distinct but developmentally linked compartments across follicular progression. Analysis of 148 sequencing libraries showed that compartment identity was the dominant source of transcriptomic variation, supporting compartment-aware downstream interpretation. Within this framework, oocytes followed a relatively continuous developmental trajectory, with substantial transcriptional remodeling already evident across adjacent stages, whereas granulosa cells showed weaker early-stage contrasts but markedly stronger late-stage reorganization, particularly around the antral and preovulatory transitions. Functional enrichment indicated that oocyte maturation was associated with RNA-processing and broader genome-regulatory remodeling, whereas granulosa maturation was dominated by progressive mitochondrial and bioenergetic activation. Co-expression analysis showed that both compartments contained strong late-stage programmes together with inverse early-state modules, indicating a shared systems-level architecture of maturation, although the hub-gene composition and biological content of these programmes were largely compartment-specific. Machine-learning validation reinforced this asymmetry: oocyte stage classification was best recovered from a compact eigengene-based representation, whereas granulosa stage discrimination was better resolved by a broader differential-expression-derived feature set. At the gene level, HSP90AA1 emerged as a stage-associated marker with compartment-specific behavior, showing progressive attenuation across oocyte development, assignment to the selected oocyte blue module, and sharper transitional dynamics in granulosa cells. Together, these findings support a model in which human folliculogenesis proceeds through coordinated but non-equivalent transcriptomic remodeling, with shared developmental logic at the systems level but distinct molecular execution in germline and somatic compartments.

Co-expression networks↗

Structure of the mouse activin receptor type II gene.

Knowledge of the structures of the activin receptor genes is crucial to our understanding of the role of the activins, inhibins, and their receptors in developmental and physiological processes. The type II activin receptor (ActRc) has been shown to be a transmembrane protein with putative serine/threonine kinase activity. Using a human ActRc type II cDNA as a probe, 18 overlapping lambda clones containing portions of the mouse ActRc type II gene were isolated from a mouse 129SvE genomic library. Sequence analysis of the exons, exon-intron boundaries, and 5' and 3' non-translated regions as well as Southern blot analysis of mouse genomic DNA were used to establish the structure of the mouse ActRc type II gene. The mouse ActRc type II gene is encoded by 11 exons and spans greater than 66 kilobases. Two large introns (introns 1 and 4) contribute the majority of the gene size and are found to delineate exons which encode important domains of the activin receptor. Analysis of the 5' region of the gene reveals several putative transcription factor binding sites which may be important for the complex transcriptional regulation of this gene.

Activin Receptors↗

Isolation and characterization of a novel cytochrome P-450-like pseudogene.

A rabbit liver P-450-like pseudogene has been isolated from a lambda phage genomic library. Sequence analysis revealed structural homology with respect to the rat P-450b and P-450e genes as well as a similar intron-exon organization. A 5'-proximal TATA box-like sequence and two 3'-distal putative polyadenylation signals were identified, and all putative intron-exon boundaries except at the 3'-splice site of intron 2 were found to follow the GT/AG rule. With allowance for apparent deletions and insertions, the structural homology of the amino acid sequence deduced from the pseudogene with respect to rabbit P-450 isozyme 2 is lower for exons 1 through 4 (18-28%) than for exons 5 through 9 (42-65%). S1 nuclease mapping showed that mRNAs complementary to the DNA sequence of exon 9 are expressed. However, due to the alterations in the pseudogene, it appears that functional P-450 would not be produced from such mRNAs.

Amino Acid Sequence↗

Molecular cloning and characterization of mouse CYP2J6, an unstable cytochrome P450 isoform.

A cDNA encoding a new cytochrome P450 was cloned from a mouse liver library. Sequence analysis revealed that this 2046-bp cDNA encodes a 501-amino acid polypeptide that is 72-94% identical to other CYP2J subfamily P450s and is designated CYP2J6. Northern analysis demonstrated that CYP2J6 transcripts are abundant in the small intestine and present at lower levels in other mouse tissues. In situ hybridization revealed that CYP2J6 mRNAs are present in luminal epithelial cells of the gastrointestinal mucosa. The CYP2J6 cDNA was expressed in Sf9 cells using baculovirus. The heterologously expressed CYP2J6 protein displayed a typical P450 CO-difference spectrum; however, the protein was unstable as evidenced by the loss of the Soret maxima at 450nm and the appearance of a 420nm peak when CYP2J6-expressing cells were disrupted by mechanical homogenization, sonication, or freeze-thaw. Immunoblotting of mouse microsomes with the anti-human CYP2J2 IgG, which cross-reacts with rodent CYP2Js, demonstrated the presence of multiple distinct murine CYP2J immunoreactive proteins in various tissues. Immunoblotting with an antibody to a CYP2J6-specific peptide detected a prominent 55-57kDa protein in Sf9 cell extracts expressing recombinant CYP2J6 but did not detect a protein of similar molecular mass in mouse small intestinal microsomes. Mixing experiments demonstrated that recombinant CYP2J6 is degraded rapidly in the presence of small intestinal microsomes consistent with proteolysis at highly sensitive sites. Sf9 cells, which express both CYP2J6 and NADPH-P450 oxidoreductase, metabolized benzphetamine but not arachidonic acid. We conclude that CYP2J6 is an unstable P450 that is active in the metabolism of benzphetamine, but not arachidonic acid.

Amino Acid Sequence↗

Isolation and expression of a mouse CB1 cannabinoid receptor gene. Comparison of binding properties with those of native CB1 receptors in mouse brain and N18TG2 neuroblastoma cells.

The predominant animal model in which the pharmacology of cannabinoids is studied is the mouse. Nonetheless, the structure and functional expression of the mouse cannabinoid receptor (CB1) gene have not been reported. We have cloned and expressed the gene for the mouse CB1 receptor and compared its properties with those of native mouse CB1 receptors in brain and N18TG2 neuroblastoma cells. The mouse CB1 gene was isolated from a mouse 129 strain genomic library. Sequence analysis of a 6-kb BamHI fragment of the mouse CB1 genomic clone indicates 95% nucleic acid identity between mouse and rat (99.5% amino acid identity) and 90% nucleic acid identity (97% amino acid identity) between mouse and human. Examination of the 5' untranslated sequence of the mouse CB1 genomic clone revealed a splice junction site approximately 60 bp upstream from the translation start site, indicating the possibility of splice variants of the CB1 receptors. The coding region of the mouse CB1 receptor was stably expressed in 293 cells, and binding by [3H]SR 141716A and [3H]CP-55,940 was determined. The Bmax and Kd values obtained with [3H]SR 141716A (921 +/- 58 fmol/mg and 0.73 +/- 0.13 nM, respectively) were similar to those of native mouse CB1 receptors in brain (Bmax of 1.81 +/- 0.44 pmol/mg, Kd of 0.16 +/- 0.01 nM) and N18TG2 cells (Bmax of 197 +/- 29 fmol/mg, Kd of 0.182 +/- 0.08 nM). The mouse CB1 receptor genomic clone will be a useful tool for studying the function and regulation of the CB1 receptor in mice.

Animals↗

Structural, functional analysis and localization of the human CAP18 gene.

CAP18 is an antimicrobial protein found in specific granules of PMNs. The human CAP18 (HCAP18) gene was cloned from a human genomic phage library. Sequence analysis revealed the HCAP18 gene to have 4 exons spanning 3 kb, including 700 bp of upstream DNA. Using 3' RACE no homologs of human HCAP18 were found in human bone marrow or leukocyte populations. By PCR analysis of a somatic cell mapping panel and fluorescence in situ hybridization of a genomic clone to metaphase chromosomes the gene was mapped to chromosome band 3p21.3. Like several other genes expressed late in PMN development the CAP18 gene did not contain typical TATA box or CCAAT sequences. Expression in Cos 7 cells permitted limited mapping of the promoter function in upstream fragments of the HCAP18 gene. Western blot, Northern blot and RT-PCR analysis show HCAP18 to be produced specifically in granulocytes. This work forms the groundwork for future analysis of the genetic regulation of this antimicrobial protein during PMN differentiation.

Antimicrobial Cationic Peptides↗

Cloning and expression analysis of a Petunia hybrida flower specific mitotic-like cyclin.

A cyclin cDNA clone (Pethy;CycB1;1) was isolated from a Petunia hybrida ovary specific cDNA library. Sequence comparison revealed that Pethy;CYCB1;1 protein is highly homologous to mitotic B1 cyclins. Northern analysis and in situ hybridisation experiments showed that its expression is developmentally regulated and restricted to flower organs. We have attempted to define some of the cell division patterns which contribute to shaping each floral organ by analysing Pethy;CycB1;1 expression on Petunia flower sections. While in sepals, epidermis and parenchyma cell division patterns were comparable, there were two distinct cell division patterns in petals. In the epidermis, Pethy;CYCB1;1 expression was found both at the petal tip and along epidermis, whereas in the parenchyma only at the petal tips. In reproductive organs cell divisions were detected only in sporophytic tissues. No signals were detected inside meiotic cells.

Cloning, Molecular↗

Cloning and characterisation of a cysteine proteinase gene expressed in amastigotes of Leishmania (L.) amazonensis.

The present study describes the cloning and characterisation of a gene encoding a cysteine proteinase isoform, Llacys1, expressed in amastigote forms of Leishmania (L.) amazonensis. Recombinant clones containing the Llacys1 gene were isolated from genomic DNA by PCR amplification and screening of an amastigote cDNA library. Sequence analysis of the Llacys1 gene showed a high identity to sequence of Leishmania (L.) pifanoi Lpcys1, Leishmania (L.) major cpa, Leishmania (L.) mexicana LCPa, and Leishmania (L.) chagasi Ldccys2. The Llacys1 gene is present in a single copy per L. (L.) amazonensis haploid genome and was mapped on a chromosome of approximately 700 kb. Two transcripts of the Llacys1 gene were identified, one of 2.4 kb transcribed in both forms of L. (L.) amazonensis, and another of 1.6 kb weakly expressed in amastigotes. Related forms of Llacys1 gene exist in other species of Leishmania genus, including L. (L.) major, L. (L.) mexicana, L. (L.) chagasi and Leishmania (V.) braziliensis. The Llacys1 expression in Escherichia coli was obtained when the nucleotide sequence corresponding to the signal sequence was deleted, suggesting that this signal sequence was recognised by Escherichia coli and cleaved, generating a truncated protein.

Amino Acid Sequence↗

Olfactory-specific cytochrome P-450. cDNA cloning of a novel neuroepithelial enzyme possibly involved in chemoreception.

We isolated cDNA clones for cytochrome P-450 genes expressed in the olfactory neuroepithelium by screening a corresponding rat cDNA library. Sequence analysis and RNA blot hybridization revealed a new cytochrome P-450, designated cytochrome P-450olf1, which is the first reported cytochrome P-450 mRNA uniquely expressed in the chemosensory organ. Cytochrome P-450olf1 shows intermediate level of sequence similarity (38-53% identity) to several liver cytochrome P-450 enzymes, suggesting that it belongs to the cytochrome P-450II family, but defines a new subfamily (cytochrome P-450IIG) within it. Cytochrome P-450II enzymes are known to process diverse organic compounds, including odorants. This, together with the specificity of cytochrome P-450olf1 to the sensory neuroepithelium, may indicate a role for this protein in olfactory reception.

Amino Acid Sequence↗

A unique Babesia bovis spherical body protein is conserved among geographic isolates and localizes to the infected erythrocyte membrane.

Using monoclonal antibody (mAb) 70/52.9, generated from a Babesia bovis fraction enriched for spherical body organelles, we have identified a 135-kDa protein containing an epitope conserved in B. bovis strains from Texas, Mexico, and Australia. The protein was localized to the spherical bodies of the babesial apical complex and was designated spherical body protein 3 (SBP3), according to the established nomenclature. Immunofluorescence studies showed binding of the 70/52.9 mAb to the infected-erythrocyte membrane region but not to their uninfected counterparts, demonstrating a host-cell association shared with the previously isolated B. bovis spherical body proteins, SBP1 and SBP2. Using mAb 70/52.9, the full-length cDNA encoding SBP3 was isolated from an expression library, sequenced, and oligonucleotide primers synthesized to amplify the genomic copy by polymerase chain reaction. The genomic copy contained no introns and was identical to the cDNA sequence with each containing a single, large open reading frame encoding a protein of 1089 residues. Analysis of the SBP3 amino acid sequence revealed no significant amino acid identity to SBP1 and SBP2 and a lack of repeated epitopes, a notable feature of the other two spherical body proteins. Labeled probes derived from the coding region of SBP3 hybridized to single fragments on Southern blots containing B. bovis genomic DNA indicating a single copy gene. With the identification of this third spherical body protein, which associates with the cytoplasmic face of the infected-erythrocyte membrane, a complement of distinct B. bovis proteins have been identified that are likely to contribute to intracellular survival, growth, and development for this parasite. The encoded protein should be valuable for functional investigations and evaluation of potential targets for host immunity.

Amino Acid Sequence↗

Mouse connexin37: gene structure and promoter analysis.

Connexin37 (Cx37) is a subunit gap junction protein which exhibits limited expression in only a few cell types, predominantly in endothelial cells and in the lung. To begin to analyze Cx37 expression, we isolated a 1.6 kb mouse Cx37 cDNA from a mouse lung cDNA library and isolated corresponding mouse genomic clones from a bacterial artificial chromosome library. Sequencing and comparison of these clones showed that the Cx37 gene contained a short first exon, an 1.0 kb single intron and a second exon containing the complete coding region and 3'-untranslated region (UTR). The 5'-UTR of the mouse cDNA showed 70% identity to that of human Cx37. Primer extension experiments performed using mouse lung RNA gave two bands of sizes consistent with the transcription start site predicted from the cDNA. Sequence analysis showed that the regions flanking exon I contained a consensus 'TATA box' 43 bp 5' from the transcription start site preceded by several putative transcription factor binding sites and a 282 bp truncated L1Md interspersed element. Luciferase reporter gene transfections suggested that an area of 268 bp 5' from the first exon acted as a basal promoter for Cx37 and that there was a strong negative regulatory element in the intron.

3' Untranslated Regions↗

Genomic organization and characterization of the promoter of rat malonyl-CoA decarboxylase gene.

Malonyl-CoA decarboxylase (MCD) catalyzes the decarboxylation of malonyl-CoA, an elongating agent for fatty acid synthesis and also known as a fuel-sensing mediator. In order to elucidate the genome organization, we isolated a 2020 bp rat MCD cDNA from rat brain cDNA library and isolated the corresponding rat genomic clones from the rat genomic PAC library. Sequencing and comparison of these clones showed that the MCD genome consists of five exons and four introns spanning approximately 17 kb. The proximal upstream region is GC-rich, lacks a TATA box, and contains a variety of putative transcriptional regulatory elements within 2 kb. A major transcriptional initiation site was identified by a primer extension at a site 157 nucleotides upstream of the translational initiation site. To investigate the transcriptional regulation of MCD, a series of 5'-deletion constructs of the 5'-flanking region were generated and cloned upstream from the luciferase reporter gene. By comparing promoter activity in CV-1 cells, we suggest that an area of -15 bp 5' from the first exon acted as a basal promoter for MCD and that there are positive cis-regulatory elements in the region from -55 to -325 bp and negative regulator elements in the region -1380 to -2240 bp.

5' Flanking Region↗

A putative pyruvate dehydrogenase alpha subunit gene from Trypanosoma cruzi.

A full-length DNA clone encoding a putative pyruvate dehydrogenase alpha subunit (E1 alpha) gene was isolated from a Trypanosoma cruzi (RA strain) DNA library. Sequencing of this clone revealed it to encode a 378 amino acid protein (M(r) 42774) with high sequence similarity to E1 alpha obtained from different sources. The highest score is obtained with human E1 alpha: 43,3% similarity. Southern blot analysis is consistent with the existence of a single copy of this putative T. cruzi E1 alpha gene per haploid genome in different parasite strains. Expression of this gene was demonstrated by Northern blot analysis and its trans-splicing acceptor site was identified by Polymerase Chain Reaction-mediated amplification of its cDNA.

Amino Acid Sequence↗

Isolation of a novel human cDNA (rhoHP1) homologous to rho genes.

A novel full-length cDNA showing homology with rho genes was isolated from a human placenta cDNA library. Sequencing of a total of 1086 nucleotides of this clone revealed an open reading frame of 630 nucleotides (210 amino acids). In view of its degree of homology to members of the Rho family of molecules (50-54% identical amino acids, 60-63% identical nucleotides within the coding region), the predicted product was designated RhoHP1(Rho-related protein HP1). Northern analysis indicated that a message about 1.2-kb long is expressed in human heart, placenta, liver, skeletal muscle, and pancreas and, with weaker intensity, in several other tissues.

Amino Acid Sequence↗

The melanoma progression-associated antigen P3.58 is identical to the intercellular adhesion molecule, ICAM-1.

The 89kd cell surface glycoprotein, P3.58, is expressed on human malignant melanomas in situ where it is associated with an increased risk of metastatic disease. Monoclonal antibodies detecting denatured P3.58 were produced and used to isolate a P3.58 encoding cDNA clone from a human melanoma lambda expression library. Sequencing of the cDNA revealed that the P3.58 antigen is identical to the leukocyte intercellular adhesion molecule 1 (ICAM-1).

Amino Acid Sequence↗

Application of molecular biology in veterinary parasitology.

The number of applications of molecular biology in veterinary parasitology is increasing rapidly. The techniques used with eukaryotic cells are generally applicable to the study of parasites and their hosts. The polymerase chain reaction is particularly important for identification and diagnosis of parasites, as well as for many other applications. With species and type specific probes or primers, sensitivities and specificities unheard of with conventional techniques can be achieved. The accumulation of more information on the DNA sequences of parasites will reveal many more unique sequences which can be used for identification, diagnosis, molecular epidemiology, vaccine development and for studying the evolutionary biology and the physiology of parasites and the host-parasite relationship. Similarly, the completion of genome projects on host organisms will greatly assist efforts to select for hosts that are genetically resistant to parasite infection. The study of the molecular biology of antiparasitic drug receptors, potential targets for chemotherapy, and the molecular genetics of drug resistance will allow molecular screens to be used with combinatorial chemistry in the search for new antiparasitic drugs, improvements to existing chemotherapeutic families and better diagnosis and monitoring of drug resistance. While there is a proliferation of molecular biology techniques, the availability of simple kits and of automated techniques and services for sequencing, library construction and oligonucleotide synthesis and other procedures is making it easier for non-specialists to apply many of the common techniques of molecular biology. Molecular biology and the benefits from its application are relevant for veterinary parasitologists in developing countries as well as developed countries and we should introduce aspects of molecular biology to the teaching and training of veterinary parasitologists.

Animals↗

Molecular cloning and expression study of Xenopus latent TGF-beta binding protein-1 (LTBP-1).

Latent transforming growth factor beta binding protein-1 (LTBP-1) is important in regulating the localization and activation of transforming growth factor beta. In this paper is reported the isolation of the full-length Xenopus LTBP-1 cDNA from screening a neurula embryo cDNA library. Sequence analysis of XLTBP-1 cDNA revealed an open reading frame of 4518 bp encoding a 1398 amino acid protein with a molecular mass of 154.1 kDa and an isoelectric point of 4.65. The Xenopus XLTBP-1 shares 61 and 65% amino acid identity with the mouse and human LTBP-1, respectively. It contains 17 epidermal growth factor-like motifs and four eight-cysteine repeats (8-Cys). RNase protection assay revealed that XLTBP-1 is a maternal and zygotic gene, while whole-mount in situ hybridization analysis performed on embryos at different stages showed that during early Xenopus development, XLTBP-1 mRNA is expressed in the Spemann organizer, prechordal and chordal mesoderm, and later on in the organizer derived tissues. These findings suggest an important role for XLTBP-1 in embryo axis formation.

Amino Acid Sequence↗