Transfer Of Genetic Information Research Articles

Biomimetic radical polymerization via cooperative assembly of segregating templates

Segregation and templating approaches have been honed by billions of years of evolution to direct many complex biological processes. Nature uses segregation to improve biochemical control by organizing reactants into defined, well-regulated environments, and the transfer of genetic information is a primary function of templating. The ribosome, wherein messenger RNA is translated into polypeptides, combines both techniques to allow for ideal biopolymer syntheses. Herein is presented a biomimetic segregation/templating approach to synthetic radical polymerization. Polymerization of a nucleobase-containing vinyl monomer in the presence of a complementary block copolymer template of low molecular weight yields high molecular weight (M(w) up to ~400,000 g mol(-1)), extremely low polydispersity (≤1.08) daughter polymers. Control is attained by segregation of propagating radicals in discrete micelle cores (via cooperative assembly of dynamic template polymers). Significantly reduced bimolecular termination, combined with controlled propagation along a defined number of templates, ensures unprecedented control to afford well-defined high molecular weight polymers.

LC–MS/MS with 2D mass mapping of skin secretions’ peptides as a reliable tool for interspecies identification inside Rana esculenta complex

Identification of species constituting Rana esculenta complex represents a certain problem as two parental species Rana ridibunda and Rana lessonae form their hybrid R. esculenta, while external signs and sizes of the members of this complex are intersected. However the composition of skin secretion consisting mainly of peptides is different for the species of the complex. LC–MS/MS is an ideal analytical tool for the quantitative and qualitative analysis of these peptides. The results covering elemental composition of these peptides, their levels in the secretion, as well as their belonging to a certain family of peptides may be visualized by means of 2D mass maps. The proposed approach proved itself to be a perspective tool for the reliable identification of all 3 species constituting R. esculenta complex. Easy distinguishing between the species may be achieved using 2D maps as fingerprints. Besides this approach may be used to study hybridogenesis and mechanisms of hemiclonal transfer of genetic information, when rapid and reliable identification of species involved in the process is required.

A Strong Deletion Bias in Nonallelic Gene Conversion

Gene conversion is the unidirectional transfer of genetic information between orthologous (allelic) or paralogous (nonallelic) genomic segments. Though a number of studies have examined nucleotide replacements, little is known about length difference mutations produced by gene conversion. Here, we investigate insertions and deletions produced by nonallelic gene conversion in 338 Drosophila and 10,149 primate paralogs. Using a direct phylogenetic approach, we identify 179 insertions and 614 deletions in Drosophila paralogs, and 132 insertions and 455 deletions in primate paralogs. Thus, nonallelic gene conversion is strongly deletion-biased in both lineages, with almost 3.5 times as many conversion-induced deletions as insertions. In primates, the deletion bias is considerably stronger for long indels and, in both lineages, the per-site rate of gene conversion is orders of magnitudes higher than that of ordinary mutation. Due to this high rate, deletion-biased nonallelic gene conversion plays a key role in genome size evolution, leading to the cooperative shrinkage and eventual disappearance of selectively neutral paralogs.

Calculations on Noncovalent Interactions and Databases of Benchmark Interaction Energies

Although covalent interactions determine the primary structure of a molecule, the noncovalent interactions are responsible for the tertiary and quaternary structure of a molecule and create the fascinating world of the 3D architectures of biomacromolecules. For example, the double helical structure of DNA is of fundamental importance for the function of DNA: it allows it to store and transfer genetic information. To fulfill this role, the structure is rigid to maintain the double helix with a proper positioning of the complementary base, and floppy to allow for its opening. Very strong covalent interactions cannot fulfill both of these criteria, but noncovalent interactions, which are about 2 orders of magnitude weaker, can. This Account highlights the recent advances in the field of the design of novel wave function theory (WFT) methods applicable to noncovalent complexes ranging in size from less than 100 atoms, for which highly accurate ab initio methods are available, up to extended ones (several thousands atoms), which are the domain of semiempirical QM (SQM) methods. Accurate interaction energies for noncovalent complexes are generated by the coupled-cluster technique, taking single- and double-electron excitations iteratively and triple-electron excitation perturbatively with a complete basis set description (CCSD(T)/CBS). The procedure provides interaction energies with high accuracy (error less than 1 kcal/mol). Because the method is computationally demanding, its application is limited to complexes smaller than 30 atoms. But researchers would also like to use computational methods to determine these interaction energies accurately for larger biological and nanoscale structures. Standard QM methods such as MP2, MP3, CCSD, or DFT fail to describe various types of noncovalent systems (H-bonded, stacked, dispersion-controlled, etc.) with comparable accuracy. Therefore, novel methods are needed that have been parametrized toward noncovalent interactions, and existing benchmark data sets represent an important tool for the development of new methods providing reliable characteristics of noncovalent clusters. Our laboratory developed the first suitable data set of CCSD(T)/CBS interaction energies and geometries of various noncovalent complexes, called S22. Since its publication in 2006, it has frequently been applied in parametrization and/or verification of various wave function and density functional techniques. During the intense use of this data set, several inconsistencies emerged, such as the insufficient accuracy of the CCSD(T) correction term or its unbalanced character, which has triggered the introduction of a new, broader, and more accurate data set called the S66 data set. It contains not only 66 CCSD(T)/CBS interaction energies determined in the equilibrium geometries but also 1056 interaction energies calculated at the same level for nonequilibrium geometries. The S22 and S66 data sets have been used for the verification of various WFT methods, and the lowest RMSE (S66, in kcal/mol) was found for the recently introduced SCS-MI-CCSD/CBS (0.08), MP2.5/CBS (0.16), MP2.X/6-31G* (0.27), and SCS-MI-MP2/CBS (0.38) methods. Because of their computational economy, the MP2.5 and MP2.X/6-31G* methods can be recommended for highly accurate calculations of large complexes with up to 100 atoms. The evaluation of SQM methods was based only on the S22 data set, and because some of these methods have been parametrized toward the same data set, the respective results should be taken with caution. For really extended complexes such as protein-ligand systems, only the SMQ methods are applicable. After adding the corrections to the dispersion energy and H-bonding, several methods exhibit surprisingly low RMSE (even below 0.5 kcal/mol). Among the various SMQ methods, the PM6-DH2 can be recommended because of its computational efficiency and it can be used for optimization (which is not the case for other SQM methods). The PM6-DH2 is the base of our novel scoring function used in in silico drug design.

Sequence Selective Recognition of Biologically Relevant RNA Duplexes

Compared to DNA, molecular recognition of double helical RNA has received relatively little attention. Until early 90’s, RNA was viewed mostly as a passive messenger in the transfer of genetic information from DNA to proteins. However, since the discovery that RNA can catalyze chemical reactions, the number and variety of non-coding RNAs and the important roles they play in biology has been growing steadily

Reproductive biology studies towards the conservation of two rare species of Colchic flora, Arbutus andrachne and Osmanthus decorus

Our study examines the structural peculiarities of the generative sphere at different phases of development, and the processes of pollination, fertilisation, and seed formation in 2 species of wild flora: Arbutus andrachne L. (Ericaceae), the eastern strawberry tree, and Osmanthus decorus (Boiss. & Balansa) Kasapligil (Oleaceae), Caucasian osmanthus. These Arcto-Tertiary plants are included in the Red Data Book of the Georgian SSR. As germinable seeds are the main factor determining species distribution and the complete transfer of genetic information, the aim of our research was to establish the self-regeneration capacity of the species under study and choose optimum conditions for seed germination, the further development of seedlings, and their ex situ conservation. It has been stated that abnormalities taking place at different stages of sexual reproduction are responsible for the low capacity for seed formation found in the studied species. In particular, these factors are as follows: a limited capacity for allogamy; a low percentage of pollen tube development, at 20%-30% for Arbutus andrachne and 15%-20% for Osmanthus decorus, despite the high fertility of pollen grain of both species (approximately 70%-80%); and the frequent occurrence of embryo degeneration. The germination of Arbutus andrachne seeds on petri dishes on agar reached 80%. The results of the present study allow for the elaboration of protocol for the propagation of these relic species and for their further ex situ conservation on the collection plot of the Department of Plant Conservation.

Analysis of bacteria from intestinal tract of FAP patients for the presence of APC-like sequences

SummaryBackgroundFamilial adenomatous polyposis (FAP) is a hereditary disease induced by germ-line mutations in the tumor suppressor APC gene. These initiate the early stages of the adenoma-carcinoma sequence in familial, but also in sporadic (in 80% to 90%), colon tumorigenesis. We found the presence of APC-like sequences in bacteria of FAP patients.Material/MethodsWe analyzed bacteria isolated from FAP patients’ rectal swabs. Total bacterial DNA was isolated and analyzed for detection of APC-like sequences using PCR. We also tested DNA homology rate and APC-like protein production.ResultsWe collected blood samples and rectal swabs from patients with confirmed diagnosis of FAP. They were analyzed for presence of sections from exon 15 of the APC gene. Most positive results were found in sections located exactly in the area called the MCR (mutation cluster region), where the highest frequency of APC gene mutations were identified. By sequencing PCR products from bacteria in section F–G together with a patient’s DNA sample and human APC gene, we found a more than 90% DNA homology rate. We also confirmed production of APC-like protein using Western blotting.ConclusionsOur results suggested two hypotheses. The APC-like protein might have same function as a truncated APC product, which is synthesized in most cases of mutations of APC gene in the MCR region in colorectal cancer cells. Alternatively, we can consider the possible existence of horizontal transfer of genetic information between eukaryotic and prokaryotic cells. Our study can be considered as a pilot project. For confirmation of our hypotheses, further research is needed.

On genetic information uncertainty and the mutator phenotype in cancer

Recent evidence supports the existence of a mutator phenotype in cancer cells, although the mechanistic basis remains unknown. In this paper, it is shown that this enhanced genetic instability is generated by an amplified measurement uncertainty on genetic information during DNA replication. At baseline, an inherent measurement uncertainty implies an imprecision of the recognition, replication and transfer genetic information, and forms the basis for an intrinsic genetic instability in all biological cells. Genetic information is contained in the sequence of DNA bases, each existing due to proton tunnelling, as a coherent superposition of quantum states composed of both the canonical and rare tautomeric forms until decoherence by interaction with DNA polymerase. The result of such a quantum measurement process may be interpreted classically as akin to a Bernoulli trial, whose outcome X is random and can be either of two possibilities, depending on whether the proton is tunnelled (X=1) or not (X=0). This inherent quantum uncertainty is represented by a binary entropy function and quantified in terms of Shannon information entropy H(X)=−P(X=1)log2P(X=1)−P(X=0)log2P(X=0). Enhanced genetic instability may either be directly derived from amplified uncertainty induced by increases in quantum and thermodynamic fluctuation, or indirectly arise from the loss of natural uncertainty reduction mechanisms.

Solution Structure and Conformational Dynamics of Deoxyxylonucleic Acids (dXNA): An Orthogonal Nucleic Acid Candidate

Orthogonal nucleic acids are chemically modified nucleic acid polymers that are unable to transfer information with natural nucleic acids and thus can be used in synthetic biology to store and transfer genetic information independently. Recently, it was proposed that xylose-DNA (dXNA) can be considered to be a potential candidate for an orthogonal system. Herein, we present the structure in solution and conformational analysis of two self-complementary, fully modified dXNA oligonucleotides, as determined by CD and NMR spectroscopy. These studies are the initial experimental proof of the structural orthogonality of dXNAs. In aqueous solution, dXNA duplexes predominantly form a linear ladderlike (type-1) structure. This is the first example of a furanose nucleic acid that adopts a ladderlike structure. In the presence of salt, an equilibrium exists between two types of duplex form. The corresponding nucleoside triphosphates (dXNTPs) were synthesized and evaluated for their ability to be incorporated into a growing DNA chain by using several natural and mutant DNA polymerases. Despite the structural orthogonality of dXNA, DNA polymerase β mutant is able to incorporate the dXNTPs, showing DNA-dependent dXNA polymerase activity.

Nonallelic Gene Conversion Is Not GC-Biased in Drosophila or Primates

Gene conversion is the unidirectional transfer of genetic information between allelic (orthologous) or nonallelic (paralogous) DNA segments. Recently, there has been much interest in understanding how gene conversion shapes the nucleotide composition of the genomic landscape. A widely held hypothesis is that gene conversion is universally GC-biased. However, direct experimental evidence of this hypothesis is limited to a single study of meiotic crossovers in yeast. Although there have been a number of indirect studies of gene conversion, evidence of GC-biased replacements gathered from such studies can also be attributed to positive selection, which has the same evolutionary dynamics as biased gene conversion. Here, we apply a direct phylogenetic approach to examine nucleotide replacements produced by nonallelic gene conversion in Drosophila and primate genomes. We find no evidence for GC-biased gene conversion in either lineage, suggesting that previously observed GC biases may be due to positive selection rather than to biased gene conversion.

Stroma-Derived Exosomes Mediate Oncogenesis in Multiple Myeloma

Abstract 625 Background.Bone marrow (BM)-derived mesenchymal stem cells (MSCs) support multiple myeloma (MM) cell growth, but little is know about the putative mechanisms that may regulate the interaction between clonal MM plasma cells and the surrounding BM milieu. It is known that cell-to-cell communication is partially mediated by exosomes. We therefore characterized the role BM-MSCs-derived exosomes as key regulators of MM pathogenesis in vivo and in vitro. Methods.MSCs were collected from BM of either healthy subjects or relapsed/refractory MM patients. MM cell lines (MM.1S; RPMI.8226) and normal BM stromal cell line (HS-5) were used. Purity of BM-MSCs was evaluated by flow cytometry (CD34−,14−, 45−, 19−, 138−; CD73+, 90+, 105+, 106+). Exosomes were collected from conditioned medium of either normal and MM BM-MSCs, or HS-5 cells; and studied using electron microscopy, immunogold labeling, and western blot for the detection of CD63 and CD81. Transfer of PKH67-fluorescently labeled exosomes to MM cells was evaluated by confocal microscopy and fluorescence plate reader. Transfer of murine-derived miRNA-containing exosomes into human MM cell lines was evaluated by qRT-PCR (exosomes were collected from BM-MSCs of C57BL/6 miRNA-15a/16-1−/− or C57BL/6 mice). miRNA expression profiling was obtained from normal (n=4) and MM (n=9) BM-MSCs-derived exosomes (TaqMan human miRNA profiling). Normal and MM BM-MSCs-derived exosomes were loaded into tissue-engineered bones (TEB) with MM.1S-GFP+/Luc+ cells: MM cell homing and MM tumor growth has been tested in vivo by using in vivo confocal microscopy and bioluminescence (BLI) imaging, respectively. Normal and MM BM-MSCs, as well as HS-5 cells, were transfected with either anti- or pre-miRNA-15a or scramble probe; and evaluated for their ability to modulate MM cell proliferation and adhesion in vitro. Results.Primary normal and MM BM-MSCs release CD63+/CD81+ exosomes, as confirmed by electron microscopy, immunogold labeling, and western blot. BM-MSCs exosomes are transferred into MM cells, as shown by confocal microscopy. This transfer was further confirmed in human MM cell lines incubated with murine (C57BL/6 miRNA-15a/16-1−/− and wild type) BM-MSCs-derived exosomes: qRT-PCR showed presence of murine miRNAs in human MM cell lines. The impact of normal and MM BM-MSCs-derived exosomes on MM cell behavior in vivo was next evaluated. MM cells co-cultured with exosomes derived from MM BM-MSCs induced rapid tumor growth at the site of the TEB scaffold, as well as rapid dissemination in the BM niches. In contrast, MM cells co-cultured with exosomes derived from normal BM-MSCs led to minimal tumor growth and minimal dissemination at distant BM niches. These results indicate that MM BM-MSCs-derived exosomes contribute to tumor growth and dissemination of MM. To further explore the mechanisms by which exosomes induce tumor growth, we performed miRNA expression profiling on exosomes isolated from both normal and MM BM-MSCs: supervised hierarchical clustering analysis showed increased expression of 24 miRNAs and reduced expression of 3 miRNAs in MM BM-MSCs-derived exosomes versus normal (1.5 fold change; P<0.05). Notably, we found that miRNA15a is significantly lower in exosomes derived from BM-MSCs of MM patients. We previously showed that miRNA15a shows lower expression in primary MM cells. We therefore sought to examine whether genetic transfer of miRNAs or lack of transfer of tumor suppressor miRNAs (such as miRNA15a) can lead to the significant change in tumor growth and dissemination in MM that we observed in vivo. We therefore transfected HS-5 stromal cells and primary normal BM-MSCs with pre-miRNA15a, and found that by over-expressing miRNA-15a in BM-MSCs inhibited MM cell proliferation and adhesion to fibronectin. Next MM cells were cultured in presence of BM-MSCs isolated from either C57BL/6 mice or C57BL/6 miRNA15a/16−/: miRNA15a-deficient BM-MSCs significantly induced MM cell proliferation (P<0.05). Moreover, exosomes isolated from HS-5 pre-miRNA15a-transfected cells both inhibited MM cell proliferation and reduced their adhesion properties. Conclusions.These findings demonstrate the existence of exosome-driven interactions between the BM milieu and MM cells, and suggest that exosomes might constitute a novel mechanism for intercellular transfer of genetic information in the form of miRNAs in clonal plasma cell disorders, such as MM. Disclosures:Roccaro:Roche: Advisory Board. Anderson:Celgene: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Ghobrial:Novartis: Advisory Board; Celgene: Advisory Board; Millennium: Advisory Board; Noxxon: Advisory board; Millennium: Research Funding; Bristol-Myers Squibb: Research Funding.

Widespread Promiscuous Genetic Information Transfer From DNA to RNA

### Widespread RNA and DNA Sequence Differences in the Human Transcriptome Li et al Science . 2011;333:53–58. New genomic studies show that the transfer of genetic information from DNA to RNA within humans is not very faithful. If true, frequent, or purposeful, then the implications for human health and disease are significant, but the burden of proof required is significant. Commentary: Molecular biology and genetics has a “central dogma.” First postulated by Francis Crick1,2 in 1958, shortly after the discovery of the double helix, it states that the molecular transfer or flow of genetic information occurs only as DNA→RNA→ protein. This argument is intrinsic to our understanding of genotypes, phenotypes, and human disease. The central “dogma,” a word whose precise meaning Crick acknowledged he did not precisely know3 and that could have been given the less glamorous moniker “hypothesis,” is frequently misunderstood as also implying high accuracy or even inflexibility.2 We now know that genetic information flow can be sometimes corrupted and can also occur in other directions in particular biological systems. A recent study by Li and colleagues,4 from the laboratory of Vivian Cheung at the University of Pennsylvania, now demonstrates apparent widespread DNA→RNA sequence differences in humans. The experiments they conducted involved sequencing reverse-transcribed RNA from cultured B cells isolated from 27 different humans and comparing them with their host genome sequences. Surprisingly, after appropriate quality controls, they discovered numerous base positions at which the RNA sequence was different from the DNA sequence in multiple molecules, a phenomenon they refer to as RDD (RNA-DNA difference). Specifically, they identified 28766 RDDs in the 27 individuals at 10210 exonic sites within 4741 genes. Each individual had high-quality RNA-based sequence data at 9.8 million sites: so, RDD was detected at a rate of 1.1×10−4 per exonic site (base) across human genes. Interestingly, they observed all 12 types …

Exclusion of plastid nucleoids and ribosomes from stromules in tobacco and Arabidopsis

Stromules are stroma-filled tubules that extend from the surface of plastids and allow the transfer of proteins as large as 550 kDa between interconnected plastids. The aim of the present study was to determine if plastid DNA or plastid ribosomes are able to enter stromules, potentially permitting the transfer of genetic information between plastids. Plastid DNA and ribosomes were marked with green fluorescent protein (GFP) fusions to LacI, the lac repressor, which binds to lacO-related sequences in plastid DNA, and to plastid ribosomal proteins Rpl1 and Rps2, respectively. Fluorescence from GFP-LacI co-localised with plastid DNA in nucleoids in all tissues of transgenic tobacco (Nicotiana tabacum L.) examined and there was no indication of its presence in stromules, not even in hypocotyl epidermal cells, which contain abundant stromules. Fluorescence from Rpl1-GFP and Rps2-GFP was also observed in a punctate pattern in chloroplasts of tobacco and Arabidopsis [Arabidopsis thaliana (L.) Heynh.], and fluorescent stromules were not detected. Rpl1-GFP was shown to assemble into ribosomes and was co-localised with plastid DNA. In contrast, in hypocotyl epidermal cells of dark-grown Arabidopsis seedlings, fluorescence from Rpl1-GFP was more evenly distributed in plastids and was observed in stromules on a total of only four plastids (<0.02% of the plastids observed). These observations indicate that plastid DNA and plastid ribosomes do not routinely move into stromules in tobacco and Arabidopsis, and suggest that transfer of genetic information by this route is likely to be a very rare event, if it occurs at all.

Opportunistic routing through conjugation in bacteria communication nanonetwork

As the field of molecular communication continues to grow, numerous solutions have been proposed to enable communication between nanomachines. Amongst these solutions, bacteria communication nanonetworks has been proposed as a promising approach for molecular communication. This is driven by a number of attractive properties found in bacteria, which includes biased motility toward the destination through chemotaxis process, as well as the ability of bacteria to transfer genetic information between each other using conjugation. Bacterial conjugation is a major mechanism for Lateral Gene Transfer (LGT) that enables information transfer among bacteria. In this paper, we propose an opportunistic routing process in bacteria communication network using these two properties. The paper presents the simulation work to analyze the performance of message delivery for three different topology shapes, which includes grid, hexagon, and T-shape topologies. The aim of simulating on different shape topologies is to determine the impact that conjugation will have to improve message delivery. In all topologies, the use of conjugation helped improve the reliability of message delivery to the destination point. The paper will analyze various commonly used metrics used in communication networks, such as the average delay, the number of messages, as well as the distribution of messages and their originating node. The conjugation process is most beneficial in complexed shaped topologies, where the directionality from the source to the destination is a number of hops apart, as represented in the T-shape topology.

Hydrogen Peroxide-Dependent DNA Release and Transfer of Antibiotic Resistance Genes in Streptococcus gordonii

Certain oral streptococci produce H(2)O(2) under aerobic growth conditions to inhibit competing species like Streptococcus mutans. Additionally, H(2)O(2) production causes the release of extracellular DNA (eDNA). eDNA can participate in several important functions: biofilm formation and cell-cell aggregation are supported by eDNA, while eDNA can serve as a nutrient and as an antimicrobial agent by chelating essential cations. eDNA contains DNA fragments of a size that has the potential to transfer genomic information. By using Streptococcus gordonii as a model organism for streptococcal H(2)O(2) production, H(2)O(2)-dependent eDNA release was further investigated. Under defined growth conditions, the eDNA release process was shown to be entirely dependent on H(2)O(2). Chromosomal DNA damage seems to be the intrinsic signal for the release, although only actively growing cells were proficient eDNA donors. Interestingly, the process of eDNA production was found to be coupled with the induction of the S. gordonii natural competence system. Consequently, the production of H(2)O(2) triggered the transfer of antibiotic resistance genes. These results suggest that H(2)O(2) is potentially much more than a simple toxic metabolic by-product; rather, its production could serve as an important environmental signal that facilitates species evolution by transfer of genetic information and an increase in the mutation rate.

Localization Pattern of Conjugation Machinery in a Gram-Positive Bacterium

Conjugation is an efficient way for transfer of genetic information between bacteria, even between highly diverged species, and a major cause for the spreading of resistance genes. We have investigated the subcellular localization of several conserved conjugation proteins carried on plasmid pLS20 found in Bacillus subtilis. We show that VirB1, VirB4, VirB11, VirD2, and VirD4 homologs assemble at a single cell pole, but also at other sites along the cell membrane, in cells during the lag phase of growth. Bimolecular fluorescence complementation analyses showed that VirB4 and VirD4 interact at the cell pole and, less frequently, at other sites along the membrane. VirB1 and VirB11 also colocalized at the cell pole. Total internal reflection fluorescence microscopy showed that pLS20 is largely membrane associated and is frequently found at the cell pole, indicating that transfer takes place at the pole, which is a preferred site for the assembly of the active conjugation apparatus, but not the sole site. VirD2, VirB4, and VirD4 started to localize to the pole or the membrane in stationary-phase cells, and VirB1 and VirB11 were observed as foci in cells resuspended in fresh medium but no longer in cells that had entered exponential growth, although at least VirB4 was still expressed. These data reveal an unusual assembly/disassembly timing for the pLS20 conjugation machinery and suggest that specific localization of conjugation proteins in lag-phase cells and delocalization during growth are the reasons why pLS20 conjugation occurs only during early exponential phase.

Horizontal transmission and retention of malignancy, as well as functional human genes, after spontaneous fusion of human glioblastoma and hamster host cells in vivo

Cell fusion in vitro has been used to study cancer, gene mapping and regulation, and the production of antibodies via hybridomas. However, in-vivo heterosynkaryon formation by cell-cell fusion has received less attention. This investigation describes the spontaneous fusion of a human glioblastoma with normal hamster cells after xenogeneic transplantation, resulting in malignant cells that express both human and hamster genes and gene products, and retention of glioblastoma traits with an enhanced ability to metastasize. Three of 7 human genes found showed translation of their proteins during serial propagation in vivo or in vitro for years; namely, CD74, CXCR4 and PLAGL2, each implicated with malignancy or glioblastoma. This supports the thesis that genetic hybridization of cancer and normal cells can transmit malignancy and also, as first described herein, regulatory genes involved in the tumor's organotypic morphology. Evidence also is increasing that even cell-free human cancer DNA can induce malignancy and transfer genetic information to normal cells. Hence, we posit that the transfer of genetic information between tumor and stromal cells, whether by cell-cell fusion or other mechanisms, is implicated in the progression of malignancy, and may further define the crosstalk between cancer cells and their stromal neighbors.

Efficient enzyme-free copying of all four nucleobases templated by immobilized RNA

The transition from inanimate materials to the earliest forms of life must have involved multiplication of a catalytically active polymer that is able to replicate. The semiconservative replication that is characteristic of genetic information transfer requires strands that contain more than one type of nucleobase. Short strands of RNA can act as catalysts, but attempts to induce efficient self-copying of mixed sequences (containing four different nucleobases) have been unsuccessful with ribonucleotides. Here we show that inhibition by spent monomers, formed by the hydrolysis of the activated nucleotides, is the cause for incomplete extension of growing daughter strands on RNA templates. Immobilization of strands and periodic displacement of the solution containing the activated monomers overcome this inhibition. Any of the four nucleobases (A/C/G/U) is successfully copied in the absence of enzymes. We conclude therefore that in a prebiotic world, oligoribonucleotides may have formed and undergone self-copying on surfaces.

Circulating Micro–RNAs in Acute Kidney Injury

Acute kidney Injury (AKI) remains a diagnostic and therapeutic dilemma. Translation of excellent basic science information into therapeutic advances in AKI now depends on early diagnosis and drug delivery before elimination of the potential for this target to influence cell injury. For instance,

An Adamantane‐Based Building Block for DNA Networks

DNA governs the storage and transfer of genetic information through generations in all living systems with the exception of some viruses. Its physicochemical nature and the Watson-Crick base pairing properties allow molecular constructions at nanometer length, thereby enabling the design of desired structural motifs, which can self-assemble to form large supramolecular arrays and scaffolds. The tailor-made DNAs have been an interesting material for such designed nanoscale constructions. However, the synthesis of specific structures with a desired molecular function is still in its infancy and therefore has to be further explored. To add a new dimension to this approach, we have synthesized a rigid three-way branched adamantane motif, which is capable of forming highly stable DNA networks. The moiety generated could serve as a useful building block for DNA-based nanoconstructions.