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Transfer region of a Bacteroides conjugative transposon contains regulatory as well as structural genes.

Conjugative transposons (CTns) are integrated elements that excise themselves from the chromosome to form a circular transfer intermediate that is transferred by conjugation to a recipient. In an earlier paper, the excision step was shown to be regulated by tetracycline and to be dependent on the regulatory gene, rteC. In this paper, we report that genes involved in conjugal transfer are also regulated by tetracycline but that regulation is more complex. Genes contained within a 20-kbp region that is sufficient for conjugal transfer were disrupted by single crossover integration events. Most of the disruptions abolished transfer of the CTn. None of them abolished excision. Antibodies to two of the proteins encoded in this region (TraG and TraN) were obtained and used to show that production of these proteins was dependent on tetracycline stimulation. Both TraG and TraN were membrane proteins. A surprising finding was that a disruption in the gene traQ increased transfer of CTnERL over 100-fold. Thus, TraQ may be a repressor protein that controls expression of transfer genes. If so, TraQ is not the only protein that controls expression of transfer genes because production of TraG and TraN in the traQ disruption mutant was still dependent on tetracycline stimulation.

Bacterial Proteins↗

German politics of genetic engineering and its deconstruction.

Policy-making, as exemplified by biotechnology policy, can be understood as an attempt to manage a field of discursivity, to construct regularity in a dispersed multitude of combinable elements. Following this perspective of politics as a textual process, the paper interprets the politicization of genetic engineering in Germany as a defence of the political as a regime of heterogeneity, as a field of 'dissensus' rather than 'consensus', and a rejection of the idea that the framing of technological transformation is an autonomous process. From its beginning in the early 1970s, genetic engineering was symbolically entrenched as a key technology of the future, and as an integral element of the German politics of modernization. Attempts by new social movements and the Green Party to displace the egalitarian imaginary of democratic discourse into the politics of genetic engineering were construed by the political élites as an attack on the political order of post-World War II Germany. The 1990 Genetic Engineering Law attempted a closure of this controversy. But it is precisely the homogenizing idiom of this 'settlement' which continues to nourish the social movements and their radical challenge to the definitions and codings of the politics of genetic engineering.

Genetic Engineering↗

Insertion of L1 elements into sites that can form non-B DNA. Interactions of non-B DNA-forming sequences.

Three rat L1 element integration (target) sites chosen at random can adopt non-B DNA structures in vitro at normal bacterial superhelical densities. These target sites contain, respectively, short, mixed (AT)n tracts that we show can form one or more cruciforms, short (GT)n tracts, or polypurine:polypyrimidine regions. These sites share no sequence homology, and a non-B DNA structure appears to be the only feature common to them all. When the right end of the L1Rn3 element which forms a complex series of non-B DNA structures including two triplexes, and its target site which undergoes cruciform extrusion, are present on the same supercoiled molecule, they compete for available supercoil energy. The amount of non-B DNA formed at each site varies with pH, the concentration of cations, and the size of the topological domain. The implication of our findings for recombination of L1 elements and for the effect of these elements on contiguous DNA sequences is discussed.

Acetaldehyde↗

An integrated culturomic and genomic database and analysis platform for methanogenic archaea.

Methanogenic archaea research is challenged by limited strain resources, fragmented genomic data, inconsistent genome quality, substantial uncultured lineages, and difficulties in laboratory culturing, hindering advances in biogas production, climate mitigation, and microbial ecology. These archaea play crucial roles in global carbon cycling and anaerobic environments, yet scattered data and unculturable strains limit systematic studies and applications. To address this, we created MethArDB (Methanogenic Archaeal Genome Database), a specialized database for methanogenic archaea, compiling 3919 genomes, 87 host-associated plasmids, and 42 phages, with standardized quality classifications (complete, scaffold, draft), protein sequences, and metadata on geography, habitats, metabolism, and inheritable elements. Integrated MethArCT (Methanogenic Archaeal Culturomics Toolkit) employs a dual-threshold orthologous/paralogous protein analysis to evaluate metabolic pathway completeness, predicting cultivation parameters and suggesting candidate cultivation strategies, including potential medium formulations and conditions, to support strain isolation. Overall, MethArDB and MethArCT form an integrated platform combining genomics and culturomics to facilitate methanogenic archaea research. Database URL:  http://methardb.cn.

Genome, Archaeal↗

The impact of psychoanalytic theory and a two-person psychology on the empathising analyst.

Traditionally 'empathy' has been viewed from the perspective of a one-person psychology and 'the facts' discovered via empathic understanding have been thought to reflect accurately what the patient was experiencing, ideally uncontaminated by anything coming from the analyst. In contrast to this position, the author argues that the analyst always actively influences what he discovers empathically. Specifically, the analyst's theoretical biases always shape what he empathically understands. The contributions of Owen Renik and, to a lesser extent, Irwin Hoffman are critically examined, with a focus on how their two-person perspectives shape the analyst's ability to empathise. Their clinical stances, which emphasise the role of corrective emotional experiences and countertransference enactments, are compared to what the author calls an 'integrated stance', which attempts to integrate elements of one- and two-person psychologies while retaining interpretation as primary in bringing about change. It is concluded that the techniques advocated by Renik and Hoffman potentially restrict empathic understanding in two ways. First, they take positions that limit the development of regressive transference reactions. Second, because they de-emphasise monitoring countertransference urges, they actively facilitate more frequent countertransference enactments, which then may not be interpreted as fully as by the analyst working from an 'integrated stance'. Clinical examples are used to illustrate differences between these two stances.

Adult↗

Buprenorphine: blending practice and research.

Although pharmacotherapy has been a mainstay in opiate addiction, not much research in the development of new opiate medications has been translated into clinical practice. In part, this is because opiate pharmacotherapy has not been an integral element of mainstream medical practice and because new medications developed by research are not available to clinicians. All that will change with the availability of buprenorphine for addiction treatment. For the first time in nearly a century, clinicians will be able to treat opiate addicts in the general medical setting, in the same manner they treat other patients. The unique pharmacological properties of buprenorphine, with its high patient acceptance, favorable safety profile, and ease of clinical administration, should facilitate its clinical integration. However, successful implementation will require changes in the understanding and attitude of clinicians, policymakers, and society.

Australia↗

Directional avoidance turns encoded by single interneurons and sustained by multifunctional serotonergic cells.

Avoidance turns in the sea slug Pleurobranchaea are responses to noxious stimuli and replace orienting turns to food stimuli after avoidance conditioning or satiation. Avoidance turns proved to be centrally patterned behaviors, the fictive expression of which could be elicited in reduced preparations and the isolated CNS. Activity in one of a bilateral interneuron pair, the A4 cells, was necessary and sufficient to drive the avoidance turn toward the contralateral side. Single A4 cells appeared to encode both turn direction and angle, in contrast to directional behaviors of other animals in which displacement angle is usually encoded by multiple units. The As1-4 cells, bilateral serotonergic cell clusters, excited the prolonged A4 burst during the turn through electrical and chemical coupling. However, during the escape swim, As1-4 became integral elements of the swim motor network, and A4 activity was entrained to the swim rhythm by alternating excitatory-inhibitory inputs, with only weak spiking. This provides a likely mechanism for the previously observed suppression of the avoidance turn by escape swimming. These observations add significant new aspects to the multiplying known functions of As1-4 and their homologs in other molluscs and point to a pivotal role of these neurons in the organization of gastropod behavior. Simple functional models predict (1) the essential actions of inhibitor neurons in the directionality of the turning network motor output and (2) an integrating role for As1-4 in the behavioral switch between turning avoidance and swimming escape, on the basis of their response to increasing stimulus intensity.

Animals↗

Cloning and expression of the human gene for transaldolase. A novel highly repetitive element constitutes an integral part of the coding sequence.

A novel highly repetitive retrotransposable element was cloned based on a limited sequence homology to the human T-cell leukemia virus and a related endogenous retroviral sequence, HRES-1. This repetitive element was found to constitute an integral part of the coding sequence of the human gene for transaldolase. In comparison with the intronless yeast gene, structural analysis of the human transaldolase genomic locus revealed that the human gene is comprised of five exons, second and third of which uniquely developed by insertion of a retrotransposable element. The 1329-base pair full-length cDNA, clone 4/2-4/1, contains an open reading frame coding for a protein of 336 amino acids with a predicted molecular mass of 38 kDa. This protein shows a 58% overall sequence homology with the 37-kDa yeast transaldolase. Antibodies raised against a 22-kDa recombinant polypeptide expressed from a 474-base pair 5' fragment of clone 4/2-4/1, containing repetitive exons 2 and 3, cross-reacted with yeast transaldolase and recognized the 38-kDa native human protein. Detection of a retrotransposon in the coding sequence of the human transaldolase gene demonstrates the importance of these repetitive elements in evolution of the eukaryotic genome.

Amino Acid Sequence↗

Integrative vectors for heterologous gene expression in Streptomyces spp.

Integrative expression vectors for heterologous expression of the genes in Streptomyces were developed. The vectors are comprised of a strong constitutive promoter, PE, a synthetic ribosome-binding site, ATG start codon, multiple cloning site, transcription terminator and hygromycin-resistance-encoding gene. The vectors also contain a ColE1 replicon for propagation in Escherichia coli and a wide-host-range Streptomyces integration element, the mini-circle, to direct the insertion of the vectors into the Streptomyces genome at the mini-circle attachment site. HyR transformants are stable in the absence of drug selection. Conjugative derivatives were also constructed by incorporating oriT, the origin of transfer of the IncP plasmid RK2, into these vectors, and conjugal transfer was demonstrated from an appropriate E. coli donor to Steptomyces lividans (Sl). Derivatives of these vectors potentially useful for gene disruption, as well as complementation, are also described. Replicative forms of the constructed mini-circle-based vectors in Sl, that co-exist with the integrated copy of the vector, were also present without any apparent instability problems. The utility of the vectors was demonstrated by expression of the gene encoding 31-O-methyltransferase, which is involved in methylation at position 31 of the immunosuppressive drug FK506, in Sl.

Base Sequence↗

Insertional inactivation of binding determinants of Streptococcus crista CC5A using Tn916.

Intermicrobial binding plays an important role in the ecology of the oral cavity because it represents one mechanism by which specific bacteria colonize dental plaque. The formation of "corncobs", a morphologically distinct microbial unit composed of Streptococcus crista and Fusobacterium nucleatum, is a highly specific binding interaction that depends on the presence of polar tufts of fimbriae on the streptococci. We have used a genetic approach to examine the role of streptococcal cell surface components involved in the binding of S. crista to F. nucleatum. Such binding may be an important component of corncob formation. A method for the genetic transformation of S. crista was used to transfer the broad host range transposon, Tn916, into the bacteria. Cells were grown to early log phase in brain heart infusion broth containing 10% fetal calf serum. The competent cells were mixed with purified DNA from pDL916, a plasmid construct consisting of Tn916 and the streptococcal/Escherichia coli shuttle vector pDL278. Over 300 transformants were screened for a reduction in binding to F. nucleatum. Five of the transformants showed a change in binding ranging from 59% to 29% of the positive control values. Southern blots revealed that the binding-deficient transformants contained the Tn916 element integrated into one of 4 different sites in the chromosome. The transposon, integrated into 4 different sites, appeared to be stable in the absence of selective pressure. Based on these findings, it appears that some strains of S. crista are naturally competent and that insertional inactivation methods can be used to facilitate the study of binding receptors in this group of oral streptococci.

Adhesins, Bacterial↗

Synchronous oscillatory activity in immature cortical network is driven by GABAergic preplate neurons.

Neurons dissociated from embryonic cerebral rat cortex form a differentiated network of synaptic connections and develop synchronous oscillatory network activity with the beginning of the second week in culture. During an initial phase lasting 3-4 d, synchronous calcium transients can be blocked completely by either CNQX or bicuculline, showing that both glutamatergic and GABAergic neurons are required for the generation of this form of activity. By manipulating dissociation and growth conditions, cultures containing different populations of GABAergic neurons were obtained. These cultures revealed that a distinct population of large GABAergic neurons is a key element in the generation of synchronous oscillatory network activity. A minimal number of two large GABAergic neurons per square millimeter are required for the occurrence of synchronous activity. Changes in the density of all other types of GABAergic or non-GABAergic neurons has no influence on the synchronous activity. Electron microscopic analysis shows that the large GABAergic neurons form an interconnected network. Exceptionally high somatodendritic innervation and extended axonal arborization enable these neurons to collect electric network activity and to distribute it effectively throughout the neuronal network. Additional experiments indicated that most neurons developing in culture to large GABAergic neurons are derived from the primordial plexiform layer and reside in the subplate at the time of birth. We suggest that they function as an integrating element that synchronizes neuronal activity during early cortical development by collecting incoming extrinsic and intrinsic signals and distributing them effectively throughout the developing cortical plate.

Animals↗

Expression, isolation, and crystallization of the catalytic domain of CopB, a putative copper transporting ATPase from the thermoacidophilic archaeon Sulfolobus solfataricus.

The P-type CPX-ATPases are responsible for the transport of heavy metal ions in archaea, bacteria, and eukaryotes. We have chosen one of the two CPX-ATPases of the thermophile Sulfolobus solfataricus, CopB (= SSO2896) for the investigation of the molecular mechanism of this integral membrane protein. We recombinately expressed three different soluble domains of this protein (named CopB-A, CopB-B, and CopB-C) in Escherichia coli and purified them to homogeneity. 3D crystals of CopB-B, the 29 kDa catalytic ATP binding/phosphorylation domain were produced, which diffracted to a resolution of 2.2 A. CopB-B has heavy metal stimulated phosphatase activity, which was half maximal in the presence of 80 microM Cu2+. The protein forms a phosphorylated intermediate with the substrate gamma-(32P)-ATP. No specific activation of the polypeptide was observed, when CopB-B phosphatase activity was tested in the presence of the purified CopB-C and CopB-A proteins, which provide the cation binding and the phosphatase domains. We conclude that CopB is a putatively copper translocating ATPase, in which structural elements integrally located in the membrane are required for full, coordinated activation of the catalytic ATP binding domain.

Adenosine Triphosphatases↗

Deciphering estrogen receptor alpha-driven transcription in human endometrial stromal cells via transcriptome, cistrome, and integration with chromatin landscape.

OBJECTIVE: To investigate estrogen receptor gene 1 (ESR1) and estrogen-driven transcription in human endometrial stromal cells. DESIGN: RNA sequencing (RNA-seq) and Cleavage Under Targets and Release Using Nuclease (Cut&Run) were performed on telomerase-immortalized human endometrial stromal cells with Clustered Regularly Interspaced Short Palindromic Repeats-mediated ESR1 activation. Hi-C-based chromatin architecture analysis (H3K27ac HiChIP) was conducted in primary endometrial stromal cells. SUBJECTS: Biopsies from two healthy, reproductive-aged volunteers with regular menstrual cycles and no history of gynecological malignancies. EXPOSURE: The ESR1-activated and control endometrial stromal cells were treated with estradiol (E2) or vehicle. Primary endometrial stromal cells were treated with vehicle or a decidualization cocktail. MAIN OUTCOME MEASURES: Differential gene expression analysis (RNA-seq) identified ligand-independent and -dependent ESR1 activity. Cut&Run profiled ESR1 genomic binding in ESR1-activated cells. H3K27ac HiChIP mapped hormone-induced changes in chromatin looping in primary cells. RESULTS: Among seven tested guide RNAs (gRNA), the ESR1-3 gRNA induced robust ESR1 activation and restored E2 responsiveness. Bulk RNA-seq revealed both ligand-dependent and -independent ESR1 transcriptional programs regulating inflammation, proliferation, and cancer-related pathways. Notably, 72% of differentially expressed genes overlapped with genes active in human endometrial tissue during the proliferative estrogen-dominant phase, supporting their physiological relevance. The Cut&Run-seq identified genome-wide ESR1 binding sites, with most binding sites located at distal regulatory elements. Integration of Cut&Run data with H3K27ac HiChIP chromatin loops linked distal ESR1 binding sites to gene promoters, including genes involved in decidualization (e.g., FOXO1) and endometrial cancer (e.g., ERRFI1, NRIP1, and EPAS1). Functional assays showed that ESR1 promotes cell viability and, in the presence of E2, enhances migration. CONCLUSION: The CRISPR-mediated ESR1 activation restores estrogen responsiveness in endometrial stromal cells. Combined transcriptomic, cistromic, and chromatin architecture analyses reveal ESR1's role in regulating decidualization and inflammation-related gene networks, with relevance to endometrial pathologies including endometrial cancer. This model serves as a powerful tool to study estrogen signaling in endometrial stromal cell biology and related pathologies.

Humans↗

Structurally distinct elements mediate internal ribosome entry within the 5'-noncoding region of a voltage-gated potassium channel mRNA.

The approximately 1.2-kb 5'-noncoding region (5'-NCR) of mRNA species encoding mouse Kv1.4, a member of the Shaker-related subfamily of voltage-gated potassium channels, was shown to mediate internal ribosome entry in cells derived from brain, heart, and skeletal muscle, tissues known to express Kv1.4 mRNA species. We also show that the upstream approximately 1.0 kb and the downstream approximately 0.2 kb of the Kv1.4 5'-NCR independently mediated internal ribosome entry; however, separately, these sequences were less efficient in mediating internal ribosome entry than when together in the complete (and contiguous) 5'-NCR. Using enzymatic structure probing, the 3'-most approximately 0.2 kb was predicted to form three distinct stem-loop structures (stem-loops X, Y, and Z) and two defined single-stranded regions (loops Psi and Omega) in the presence and absence of the upstream approximately 1.0 kb. Although the systematic deletion of sequences within the 3'-most approximately 0.2 kb resulted in distinct changes in expression, enzymatic structure probing indicated that local RNA folding was not completely altered. Structure probing analysis strongly suggested an interaction between stem-loop X and a downstream polypyrimidine tract; however, opposing changes in activity were observed when sequences within these two regions were independently deleted. Moreover, deletions correlating with positive as well as negative changes in expression altered RNase cleavage within stem-loop X, indicating that this structure may be an integral element. Therefore, these findings indicate that Kv1.4 expression is mediated through a complex interplay between many distinct RNA regions.

5' Flanking Region↗

Point mutations implicate repeated sequences as essential elements of the CYC7 negative upstream site in Saccharomyces cerevisiae.

The transcription of the CYC7 gene of Saccharomyces cerevisiae, encoding the iso-2-cytochrome c protein, is controlled by two upstream regulatory elements, a positive element and a negative element. The nature of the DNA sequences in the negative element were investigated in a two-part approach. The first involved the construction of a CYC7-galK fusion gene which placed the coding sequence of the Escherichia coli galactokinase gene under the regulation of the CYC7 upstream sequences. This fusion allowed the quantitation by galactokinase enzyme assays of the effects on gene expression of a variety of previously isolated deletion mutations within the negative site. The results suggested that the negative site contained three related sequences. This hypothesis was tested in the second part of these studies, the selection of point mutations within the region of the negative site which led to increased CYC7 expression. Point mutations were introduced by a technique which induced mutations within a localized region at high efficiency. All but one of the mutations involved more than a single base-pair change. The mutations followed the pattern that multiple base-pair changes occurred in one repeat or single base-pair changes occurred in two repeats, with the exception of one mutant, which had a single base-pair change in one repeat. This pattern of mutations and the base pairs that were altered strongly supported the hypothesis that the repeats are integral elements of the negative site.

Base Sequence↗

Laminin-5 and hemidesmosomes: role of the alpha 3 chain subunit in hemidesmosome stability and assembly.

Hemidesmosomes are complex macromolecular structures which integrate elements of the extracellular matrix and the cytoskeleton of epithelial cells. To characterize cell-matrix interactions in the hemidesmosome, we have made use of 804G cells which possess the unusual ability to assemble hemidesmosomes in vitro. During the course of our studies, we have raised a set of monoclonal antibodies against rat laminin-5, the major structural element comprising 804G matrix. One of these, termed CM6, recognizes the 150 kDa alpha chain of rat laminin-5 and binds the globular (G) domain of intact laminin-5 molecules as determined by rotary shadowing. CM6 antibodies perturb formed hemidesmosomes in 804G cells. In particular, within 1 hour of incubation of 804G cells with CM6 antibodies, colocalization of laminin-5 and alpha 6 beta 4 integrin is lost and by 2 hours, staining generated by hemidesmosomal antibodies appears primarily cytoplasmic in the perinuclear zone. Ultrastructurally, CM6 antibodies first appear to induce detachment of hemidesmosomes from the underlying matrix. Next, portions of the basal cell surface invaginate to form vesicles whose cytoplasmic-facing surface is coated with hemidesmosomes still associated with keratin intermediate filaments. Anchoring filaments extend into the inside compartment of the vesicles. We have also studied the impact of CM6 antibodies on a model system in which the matrix of 804G cells induces de novo assembly of hemidesmosomes in human keratinocytes. This process involves the plasma membrane reorganization of the hemidesmosome associated integrin alpha 6 beta 4 as well as a redistribution of other hemidesmosome components such as the 230 kDa bullous pemphigoid antigen. Pretreatment of 804G matrix with CM6 antibodies blocks such plasma membrane reorganization of hemidesmosome components and inhibits hemidesmosome formation. Our studies indicate a crucial role for the G domain of the alpha chain of laminin-5 in both nucleation of hemidesmosome assembly as well as maintenance of hemidesmosome structural integrity.

Amino Acid Sequence↗

Purified mariner (Mos1) transposase catalyzes the integration of marked elements into the germ-line of the yellow fever mosquito, Aedes aegypti.

Derivatives of the mariner transposable element, Mos1, from Drosophila mauritiana, can integrate into the germ-line of the yellow fever mosquito, Aedes aegypti. Previously, the transposase required to mobilize Mos1 was provided in trans by a helper plasmid expressing the enzyme under the control of the D. psuedoobscura heat-shock protein 82 promoter. Here we tested whether purified recombinant Mos1 transposase could increase the recovery of Ae. aegypti transformants. Mos1 transposase was injected into white-eyed, kh(w)/kh(w), Ae. aegypti embryos with a Mos1 donor plasmid containing a copy of the wild-type allele of the D. melanogaster cinnabar gene. Transformed mosquitoes were recognized by partial restoration of eye color in the G(1) animals and confirmed by Southern analyses of genomic DNA. At Mos1 transposase concentrations approaching 100 nM, the rate of germ-line transformants arising from independent insertions in G(0) animals was elevated 2-fold compared to that seen in experiments with helper plasmids. Furthermore, the recovery of total G(1) transformants was increased 7.5-fold over the frequency seen with co-injected helper plasmid. Southern blot analyses and gene amplification experiments confirmed the integration of the transposons into the mosquito genome, although not all integrations were of the expected cut-and-paste type transposition. The increased frequency of germ-line integrations obtained with purified transposase will facilitate the generation of Mos1 transgenic mosquitoes and the application of transgenic approaches to the biology of this important vector of multiple pathogens.

Aedes↗

Identification and Ds-tagged isolation of a new gene at the Cf-4 locus of tomato involved in disease resistance to Cladosporium fulvum race 5.

Leaf mould disease in tomato is caused by the biotrophic fungus Cladosporium fulvum. An Ac/Ds targeted transposon tagging strategy was used to isolate the gene conferring resistance to race 5 of C. fulvum, a strain expressing the avirulence gene Avr4. An infection assay of 2-week-old seedlings yielded five susceptible mutants, of which two had a Ds element integrated in the same gene at different positions. This gene, member of a gene family, showed high sequence homology to the C. fulvum resistance genes Cf-9 and Cf-2. The gene is predicted to encode an extracellular transmembrane protein containing a divided domain of 25 leucine-rich repeats. Three mutants exhibited a genomic deletion covering most of the Lycopersicon hirsutum introgressed segment, including the Cf-4 locus. Southern blot analysis revealed that this deletion includes the tagged gene and five homologous sequences. To test whether the tagged gene confers resistance to C. fulvum via Avr4 recognition, the Avr4 gene was expressed in planta. Surprisingly, expression of the Avr4 gene still triggered a specific necrotic response in the transposon-tagged plants, indicating that the tagged resistance gene is not, or is not the only gene, involved in Avr4 recognition. Mutants harbouring the genomic deletion did not show this Avr4-specific response. The deleted segment apparently contains, in addition to the tagged gene, one or more other genes, which play a role in the Avr4 responses. The tagged gene is present at the Cf-4 locus, but it does not necessarily recognize Avr4 and is therefore designated Cf-4A.

Amino Acid Sequence↗