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Since the end of the 1980s and the advent of molecular biology, then the beginning of the 2000s with the sequencing of whole genomes, modern tools have never ceased to amaze us and provide answers to questions that we didn't even dare ask ourselves before: Why do elephants have fewer cancers than humans? Why do humans have such big brains? How does a eukaryotic cell recognize a "foreign" DNA sequence? Are there molecular crossroads of incompatible functions? Can cells count each other? These fascinating questions have made biology in recent years almost crazy.

In the present review, numerous experimental and theoretical data describing the properties of non-canonical DNA structures (NSs) are analyzed. NSs (G-quadruplex, i-motif, hairpin, and triplex) play an important role in epigenetic processes (including the genetic variability of viruses), are prone to energetically low-cost conformational transformations and can very effectively be used in the design of nanoscale devices. Numerous experimental data have been analyzed in connection with the so-called oligonucleotides-transformers (nucleotide sequences that able to fold not only into one, but also into several NSs). These sequences were recently predicted by our calculations using automata and graph theories ("Dafna" algorithm). Possible applications of the oligonucleotides-transformers in nanoengineering and genetic editing of organisms are considered., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A systematic search for non-conventional open reading frames in human DNA reveals a large number of small ORFs encoding peptides generally smaller than 100 amino-acids. These ORFs are transcribed and translated into small proteins, which are demonstrated to have functional significance by bulk CRISPR inactivation. Evidence is also found for bicistronic mRNAs including such a small ORF upstream of a canonical coding sequence. These findings add a new facet to our understanding of biological processes., (© 2020 médecine/sciences – Inserm.)

Gene structure and expression regulation mechanism are the research hotspots and focus of modern life sciences. The lac operon is a cluster of genes through which Escherichia coli catabolizes lactose. It was first proposed by F. Jacob and J. Monod, who were also awarded the Nobel Prize in Physiology or Medicine in 1965 for their contributions. Thereafter, the lac operon has become the classic teaching case of the gene regulation mechanism in microbiology, genetics and molecular biology, and been highly valued by teachers and students alike. Although the conclusion is easy to follow and memorize, its rich connotation and esoteric reasoning has rendered it difficult to understand, neither is it easy for teachers to fully exploit the advantages of this teaching case. Therefore it is necessary to have an in-depth understanding of the genetic structure and working principle of the lac operon, especially the scientific background and thinking process through which scientists revealed these mysteries. In this paper, the historical discovery and analysis process of the E. coli lac operon was reviewed by following their footprints, listening to their analysis of experimental results. Based on the DNA sequences, the reasons for several unusual phenomena of lac operon expression were also discussed to exemplify the teaching value of the classic cases in genetics and molecular biology.

In this study, we develop a program that allows us to reveal DNA receptors, i.e. nucleotide sequences that may form more than one non-canonical structure. The data obtained may be analysed either experimentally or using DNA banks, and refers to the coding, non-coding or promotor region of the gene. These results provide a better understanding of the role that non-canonical structures play in pathological modifications of the genetic apparatus, resulting in tumour formation or inherited disease. They also reveal the effect of single nucleotide polymorphisms on gene expression, indicate so-called "risk regions" in which the substitution of a single nucleotide may lead to increased formation of non-canonical structures, and elucidate the epigenetic mechanisms of microorganism adaptation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Recent methodological advances allowed the identification of an increasing number of RNA-binding proteins (RBPs) and their RNA-binding sites. Most of those methods rely, however, on capturing proteins associated to polyadenylated RNAs which neglects RBPs bound to non-adenylate RNA classes (tRNA, rRNA, pre-mRNA) as well as the vast majority of species that lack poly-A tails in their mRNAs (including all archea and bacteria). We have developed the Phenol Toluol extraction (PTex) protocol that does not rely on a specific RNA sequence or motif for isolation of cross-linked ribonucleoproteins (RNPs), but rather purifies them based entirely on their physicochemical properties. PTex captures RBPs that bind to RNA as short as 30 nt, RNPs directly from animal tissue and can be used to simplify complex workflows such as PAR-CLIP. Finally, we provide a global RNA-bound proteome of human HEK293 cells and the bacterium Salmonella Typhimurium.

Many developmental processes involve transitions between different cell identities as cells differentiate or undergo reprogramming. Cell identity specifications are generally associated with the activation and suppression of specific sets of genes mediated by transcription factors. Therefore, transcriptional reporters, such as promoters of cell-type-specific genes, are broadly used as cell identity markers in developmental biology. In Arabidopsis (Arabidopsis thaliana), a collection of GAL4/UAS enhancer trap lines is an established standard for inferring cell identity. However, only a few of these enhancer trap lines have been molecularly characterized, which limits their potential. Here, we describe an approach for a detailed characterization of expression and mapping of T-DNA insert location of GAL4/UAS enhancer trap lines. Additionally, we demonstrate how the acquired information can be further used for the generation of novel cell-type-specific promoters as well as for genotyping of enhancer trap lines.

The potential of alternative oxidase (AOX) genes to develop functional markers for plant breeding programs has been emphasized. In this sense, it is essential to have a reliable classification system, which could aid in the selection of candidate AOX genes from different species. In the case of angiosperms AOX, a robust classification system is required because this enzyme is encoded by variable gene numbers (1-6 genes) with variable AOX subfamilies and subtypes. Thus, in this protocol, we present a detailed guideline to application of a classification scheme of AOX based on specific amino acids and phylogeny. We believe that this classification protocol provides an easier and practical way of classifying new angiosperm AOX genes besides that it can help to standardize AOX gene names used in AOX research community.

Silencing of cardiac genes by RNA interference (RNAi) has developed into a powerful new method to treat cardiac diseases. Small interfering (si)RNAs are the inducers of RNAi, but cultured primary cardiomyocytes and heart are highly resistant to siRNA transfection. This can be overcome by delivery of small hairpin (sh)RNAs or artificial microRNA (amiRNAs) by cardiotropic adeno-associated virus (AAV) vectors. Here we describe as example of the silencing of a cardiac gene, the generation and cloning of shRNA, and amiRNAs directed against the cardiac protein phospholamban. We further describe the generation of AAV shuttle plasmids with self complementary vector genomes, the production of AAV vectors in roller bottles, and their purification via iodixanol gradient centrifugation and concentration with filter systems. Finally we describe the preparation of primary neonatal rat cardiomyocytes (PNRC), the transduction of PNRC with AAV vectors, and the maintenance of the transduced cell culture.

Single nucleotide polymorphisms (SNPs) in DNA can result in phenotypes where the biochemical basis may not be clear due to the lack of protein structures. With the growing number of modeling and simulation software available on the internet, students can now participate in determining how small changes in genetic information impact cellular protein structure and function. We have developed a modular series of activities to engage lab or lecture students in examining the basis for common phenotypes. The activities range from basic phenotype testing/observation to DNA sequencing and simulation of protein structure and dynamics. We provide as an example study of the bitterness receptor TAS2R38 and PTC tasting, however these activities are applicable to other SNPs or genomic variants with a direct connection to an observable phenotype. These activities are modular and can be mixed to meet the student capabilities and infrastructure availability. The complete sequence of activities will demonstrate the direct connection between gene structure, protein structure and organism function. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(6):526-536, 2016., (© 2016 The International Union of Biochemistry and Molecular Biology.)

Background: As an agriculturally important oomycete genus, Phytophthora contains a large number of destructive plant pathogens that severely threaten agricultural production and natural ecosystems. Among them is the broad host range pathogen P. palmivora, which infects many economically important plant species. An essential way to dissect their pathogenesis mechanisms is genetic modification of candidate genes, which requires effective transformation systems. Four methods were developed for transformation of Phytophthora spp., including PEG(polyethylene glycol)/CaCl2 mediated protoplast transformation, electroporation of zoospores, microprojectile bombardment and Agrobacterium-mediated transformation (AMT). Among them, AMT has many advantages over the other methods such as easy handling and mainly generating single-copy integration in the genome. An AMT method previously reported for P. infestans and P. palmivora has barely been used in oomycete research due to low success and low reproducibility., Results: In this study, we report a simple and efficient AMT system for P. palmivora. Using this system, we were able to reproducibly generate over 40 transformants using zoospores collected from culture grown in a single 100 mm-diameter petri dish. The generated GFP transformants constitutively expressed GFP readily detectable using a fluorescence microscope. All of the transformants tested using Southern blot analysis contained a single-copy T-DNA insertion., Conclusions: This system is highly effective and reproducible for transformation of P. palmivora and expected to be adaptable for transformation of additional Phytophthora spp. and other oomycetes. Its establishment will greatly accelerate their functional genomic studies.

Zona radiata proteins are essential for ensuring bactericidal resistance, oocyte nutrients uptake and functional buoyancy, sperm binding and guidance to the micropyle, and protection to the growing oocyte or embryo from the physical environment. Such glycoproteins have been characterized in terms of molecular structure, protein composition and phylogenetics in several chordate models. Nevertheless, research on teleost has not been extensive. In Clupeiformes, one of the most biologically relevant and commercially important order which accounts for over 400 species and totally contributes to more than a quarter of the world fish catch, Egg Envelope Protein (EEP) information exist only for the Clupea pallasii and Engraulis japonicus species. The European anchovy, Engraulis encrasicolus, the target of a well-consolidated fishery in the Mediterranean Sea, has been ignored until now and the interest on the Otocephala superorder has been fragmentally limited to some Cypriniformes and Gonorynchiformes, as well. The aim of the present study was to fill the ZP protein-wise gap of knowledge afflicting the understanding of the European anchovy's reproductive process and to expand the background on Clupeiformes. We cloned the five Engraulis encrasicolus' zp genes and deduced their products, determined their tissue distribution, quantified their mRNA expression throughout the reproductive cycle and provided an insight into their evolution through phylogenetic tools. Furthermore, we proposed a multivariate statistics-based method to objectively infer and/or confirm the classification of Engraulis encrasicolus' sexual maturity stages by analyzing data of zp mRNAs' relative abundance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

CRISPR/Cas9 genome editing technology is used in the manipulation of genome sequences and gene expression. Because of the ease and rapidity with which genes can be mutated using CRISPR/Cas9, we sought to determine if a single-semester undergraduate class could be successfully taught, wherein students isolate mutants for specific genes using CRISPR/Cas9. Six students were each assigned a single Drosophila gene, for which no mutants currently exist. Each student designed and created plasmids to encode single guide RNAs that target their selected gene; injected the plasmids into Cas9-expressing embryos, in order to delete the selected gene; carried out a three-generation cross to test for germline transmission of a mutated allele and generate a stable stock of the mutant; and characterized the mutant alleles by PCR and sequencing. Three genes out of six were successfully mutated. Pre- and post- survey evaluations of the students in the class revealed that student attitudes towards their research competencies increased, although the changes were not statistically significant. We conclude that it is feasible to develop a laboratory genome editing class, to provide effective laboratory training to undergraduate students, and to generate mutant lines for use by the broader scientific community. © 2016 by The International Union of Biochemistry and Molecular Biology, 44:263-275, 2016., (© 2016 The International Union of Biochemistry and Molecular Biology.)

In an effort to gain greater understanding of the biology and infection processes of Helicobacter pylori, we have expanded the functionality of the tetracycline-dependent gene regulation (tet) system to provide more improved and versatile genetic control and facilitate the generation of conditional mutants to study essential genes. Second-generation tetracycline-responsive H. pylori uPtetO5 promoters were based on the mutated core ureA promoter. Single point mutations at either the ribosomal binding site or the start codon were introduced to shift the regulatory range of three uPtetO5 derivatives. All promoters were tested for regulation by TetR and revTetR using dapD, a gene essential to peptidoglycan biosynthesis, as a reporter. All tet promoters were effectively regulated by both TetR and revTetR, and their regulation windows overlapped so as to cover a broad range of expression levels. tet promoters uPtetO5m1 and uPtetO5m2 could be sufficiently silenced by both TetR and revTetR so that the conditional mutants could not grow in the absence of diaminopimelic acid (DAP). Furthermore, through the use of these inducible promoters, we reveal that insufficient DAP biosynthesis results in viable cells with altered morphology. Overall, the development and optimization of tet regulation for H. pylori will not only permit the study of essential genes but also facilitate investigations into gene dosage effects on H. pylori physiology., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Here we describe approaches and methods to assaying in vitro the major variant bacterial sigma factor, Sigma 54 (σ(54)), in a purified system. We include the complete transcription system, binding interactions between σ54 and its activators, as well as the self-assembly and the critical ATPase activity of the cognate activators which serve to remodel the closed promoter complexes. We also present in vivo methodologies that are used to study the impact of physiological processes, metabolic states, global signalling networks, and cellular architecture on the control of σ(54)-dependent gene expression.

The domains of large ribozymes are composed of secondary structural elements that fold independently in solution. Interactions between these structures contribute to the overall structure of the ribozyme. These elements can also be deleted, reducing catalytic activity, and their structure-function relationships determined by assaying the ability of variant elements to activate the deleted ribozyme in trans. This is illustrated for an unusual loop structure from Bacillus subtilis Ribonuclease P RNA.

Heavy metal cleavage mapping analysis of both assembling and fully mature ribonucleoprotein (RNP) complexes are informative techniques for assessing the intermolecular base pairing between small non-coding RNAs and their interacting target RNAs. Lead cleavage of the RNA in partially or fully assembled RNPs in the absence or presence of the interacting RNA can determine both the accessibility of the base pairing sequence within the RNP itself as well as its interaction with the target RNA. In this chapter, we detail how this technique was used to map the intermolecular RNA:RNA base pairing of a box C/D RNA with its target RNA within the assembling archaeal RNP complex.

Construction of long RNAs can be achieved in vitro by using ribozymes to recombine shorter RNAs. This can be a useful technique to prepare RNAs when the final product is either very long or contains chemical modifications that are difficult to incorporate using standard in vitro transcription techniques. Here, we describe the use of the Azoarcus group I intron ribozyme to recombine shorter RNAs into longer ones. This ribozyme is a generalized RNA recombinase ribozyme that operates rapidly and with high efficiency.

RNA polymerase is a complex machinery, which is further embedded in interactions with other cellular components that interplay with either the transcribed DNA (DNA polymerases, topoisomerases, etc.) or the nascent RNA (RNA processing enzymes, ribosomes, etc.). In prokaryotes, coupling of transcription and translation is thought to play many regulatory roles but the mechanistic understanding of their interactions has been hindered by the lack of a defined experimental system. Here, we describe a pure transcription-coupled-to-translation system in which control of the ribosome has been achieved through its stepwise translocation towards RNA polymerase. This system can be used to study the effects of concurrent translation on RNA chain elongation and to elucidate the interface between the two macromolecular complexes.

RNA-protein interactions play important roles in gene regulation, functional RNA-protein complexes such as the ribosome, and in viral replication. Molecules that regulate specific RNA-protein interactions may be used to dissect biological processes, and to establish the validity of targeting an RNA-protein interaction. There are many examples of biological regulation by antisense RNA stem-loops that form loop-loop and loop-linear RNA-RNA interactions. Here, a bacterial reporter system for the identification of RNA stem-loops that inhibit the formation of RNA-protein complexes through RNA-RNA interactions is described.

Infectious cDNA clones are now indispensible tools for the genetic analysis of viral factors involved in viral virulence and host resistance. In addition, infectious cDNA-derived virus vectors that express foreign genes in infected plants enable the production of useful proteins at low cost and can confer novel crop traits. We constructed infectious cDNA clones derived from two potyviruses, Clover yellow vein virus and Bean yellow mosaic virus, which infect legume plants and cause disease. Here, we present our procedure for constructing these potyvirus infectious clones.

High-efficiency DNA ligation is vital for many molecular biology experiments, and it is best achieved using reactants with non-palindromic sticky ends to maximize specificity. However, optimizing such multi-parametric ligation reactions often involves extensive trial and error. We have developed a freely available Web-based ligation calculator, NP-Sticky (http://sarkarlab.umn.edu/npsticky/), that predicts product distribution for given reactant concentrations, thus enabling straightforward computational optimization of these reactions. Built-in schemes include two-piece and three-piece linear ligation, as well as insert-vector circular ligation. The only parameters needed for the underlying thermodynamic model are the free energies of ligation for each sticky end, which can be estimated by the calculator from the overhang sequences or provided by the user from direct experimental measurement. Free energies of sticky-end mismatches are also calculated for determining the extent of byproduct formation. This ligation calculator allows rapid identification of the optimal conditions for maximizing incorporation, efficiency, and/or accuracy, based on specific needs., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The Standard European Vector Architecture (SEVA) toolkit is a simple and powerful resource for constructing optimal plasmid vectors based on a backbone and three interchangeable modules flanked by uncommon restriction sites. Functional modules encode several origins of replication, diverse antibiotic selection markers, and a variety of cargoes with different applications. The backbone and DNA modules have been minimized and edited for flaws in their sequence and/or functionality. A protocol for the utilization of the SEVA platform to construct transcriptional and translational fusions between a promoter under study (the arsenic-responsive Pars of Pseudomonas putida KT2440) and the reporter lacZ gene is described. The resulting plasmid collection was instrumental to measure and compare the β-galactosidase activity that report gene expression (i.e., transcription and translation) in different genetic backgrounds.

Pre-mRNA splicing is a critical step in eukaryotic gene expression, which involves removal of noncoding intron sequences from pre-mRNA and ligation of the remaining exon sequences to make a mature message. Splicing is carried out by a large ribonucleoprotein complex called the spliceosome. Since the first description of the pre-mRNA splicing reaction in the 1970s, elegant genetic and biochemical studies have revealed that the enzyme that catalyzes the reaction, the spliceosome, is an exquisitely dynamic macromolecular machine, and its RNA and protein components undergo highly ordered, tightly coordinated rearrangements in order to carry out intron recognition and splicing catalysis. Studies using the genetically tractable unicellular eukaryote budding yeast (Saccharomyces cerevisiae) have played an instrumental role in deciphering splicing mechanisms. In this chapter, we discuss how yeast genetics has been used to deepen our understanding of the mechanism of splicing and explore the potential for future mechanistic insights using S. cerevisiae as an experimental tool.

The discovery of 5-hydroxymethylcytosine (5hmC) as an abundant base in mammalian genomes has excited the field of epigenetics, and stimulated an intense period of research activity aimed at decoding its biological significance. However, initial research efforts were hampered by a lack of assays capable of specifically detecting 5hmC. Consequently, the last 3 years have seen the development of a plethora of new techniques designed to detect both global levels and locus-specific profiles of 5hmC in mammalian genomes. This research effort has culminated in the recent publication of two complementary techniques for quantitative, base-resolution mapping of 5hmC in mammalian genomes, the first true mammalian hydroxymethylomes. Here, we review the techniques currently available to researchers studying 5hmC, discuss their advantages and disadvantages, and explore the technical hurdles which remain to be overcome.

Cordyceps militaris and Ophiocordyceps sinensis (syn. Cordyceps sinensis), 2 well-known traditional Chinese medicines, contain the same bioactive components and share a similar developmental process. In this study, one C. militaris strain preserved in our laboratory was proven to be a MAT1 mating-type strain using a polymerase chain reaction-based mating-type assay. A 5000-bp nucleotide sequence of the mating-type MAT1-1 from C. militaris was amplified by thermal asymmetric interlaced polymerase chain reaction, but genes within the mating-type MAT1-2 remain undetectable. Sequence analysis shows that the mating-type gene MAT1-1 idiomorph contains 2 genes, MAT1-1-1 and MAT1-1-2. The MAT1-1-1 gene consists of 1480-bp nucleotides that encode 456 amino acids and contain the conserved a-box domain interrupted by 2 introns; the MAT1-1-2 gene consists of 1066 nucleotides that encode 377 amino acids interrupted by one intron. The intervening distance between MAT1-1-1 and MAT1-1-2 is 778 bp. The C. militaris MAT1-1 idiomorph organization is the same as that of Cordyceps takaomontana. The MAT1-1 mating-type idiomorph of both Cordyceps species lacks the MAT1-1-3 gene, which is typically present in Pyrenomycetes. These studies provide some insights for further study of the morphological development of C. militaris and will eventually benefit the domestication of O. sinensis.

In eukaryotic organisms, nascent transcripts of protein-coding genes contain intronic sequences that are not present in mature mRNAs. Pre-mRNA splicing removes introns and joins exons to form mature mRNAs. It is catalyzed by a large RNP complex called the spliceosome. Sequences within the pre-mRNA determine intron recognition and excision. This process occurs with a high degree of accuracy to generate the functional transcriptome of a cell.

RNA processing by the splicing machinery removes intronic sequences from pre-mRNA to generate mature mRNA transcripts. Many splicing events occur co-transcriptionally when the pre-mRNA is still associated with the transcription machinery. This mechanism raises questions regarding the number of spliceosomes associated with the pre-mRNA at a given time. In this protocol, we present a quantitative FISH approach that measures the ratio of intensities between two different spliceosomal components associated on a nascent mRNA, and compares to the number of introns in the mRNA, thereby calculating the number of spliceosome complexes assembled with each transcript.

Pre-messenger RNA splicing is a surprisingly complex and dynamic process, the details of which remain largely unknown. One important method for studying splicing involves the replacement of endogenous splicing components with their synthetic counterparts. This enables changes in protein or nucleic acid sequence to be tested for functional effects, as well as the introduction of chemical moieties such as cross-linking groups and fluorescent dyes. To introduce the modified component, the endogenous one must be removed and a method found to reconstitute the active splicing machinery. In extracts prepared from S. cerevisiae, reconstitution has been accomplished with the small, nuclear RNAs U6, U2, and U5.We describe a comparable method to reconstitute active U4 small, nuclear RNA (snRNA) into a splicing extract. In order to remove the endogenous U4 it is necessary to target it for oligo-directed RNase H degradation while active splicing is under way, i.e., in the presence of a splicing transcript and ATP. This allows complete degradation of endogenous U4 and subsequent replacement with an exogenous version. In contrast to the procedures described for depletion of U6, U2, or U5 snRNAs, depletion of U4 requires concurrent active splicing. The ability to reconstitute U4 in yeast extract allows a variety of structural and functional studies to be carried out.

The evolution of RNA interference (RNAi) and the development of technologies exploiting its biology have enabled scientists to rapidly examine the consequences of depleting a particular gene product in cells. Design tools have been developed based on experimental data to increase the knockdown efficiency of siRNAs. Not all siRNAs that are developed to a given target mRNA are equally effective. Currently available design algorithms take an accession, identify conserved regions among their transcript space, find accessible regions within the mRNA, design all possible siRNAs for these regions, filter them based on multi-scores thresholds, and then perform off-target filtration. These different criteria are used by commercial suppliers to produce siRNA genome-wide libraries for different organisms. In this article, we analyze existing siRNA design algorithms and evaluate weight of design parameters for libraries produced in the last decade. We proved that not all essential parameters are currently applied by siRNA vendors. Based on our evaluation results, we were able to suggest an siRNA sequence pattern. The findings in our study can be useful for commercial vendors improving the design of RNAi constructs, by addressing both the issue of potency and the issue of specificity.

In this report, we describe a 5-week laboratory exercise for undergraduate biology and biochemistry students in which students learn to sequence DNA and to genotype their DNA for selected single nucleotide polymorphisms (SNPs). Students use miniaturized DNA sequencing gels that require approximately 8 min to run. The students perform G, A, T, C Sanger sequencing reactions. They prepare and run the gels, perform Southern blots (which require only 10 min), and detect sequencing ladders using a colorimetric detection system. Students enlarge their sequencing ladders from digital images of their small nylon membranes, and read the sequence manually. They compare their reads with the actual DNA sequence using BLAST2. After mastering the DNA sequencing system, students prepare their own DNA from a cheek swab, polymerase chain reaction-amplify a region of their DNA that encompasses a SNP of interest, and perform sequencing to determine their genotype at the SNP position. A family pedigree can also be constructed. The SNP chosen by the instructor was rs17822931, which is in the ABCC11 gene and is the determinant of human earwax type. Genotypes at the rs178229931 site vary in different ethnic populations., (© 2013 by The International Union of Biochemistry and Molecular Biology.)

Evolution is a defining criterion of life and is central to understanding biological systems. However, the timescale of evolutionary shifts in phenotype limits most classroom evolution experiments to simple probability simulations. In vitro directed evolution (IVDE) frequently serves as a model system for the study of Darwinian evolution but produces noticeable phenotypic shifts in a matter of hours. An IVDE demonstration lab would serve to both directly demonstrate how Darwinian selection can act on a pool of variants and introduce students to an essential method of modern molecular biology. To produce an IVDE demonstration lab, continuous IVDE of a T500 ribozyme ligase population has been paired with a fluorescent strand displacement reporter system to visualize the selection of improved catalytic function. A ribozyme population is taken through rounds of isothermal amplification dependent on the self-ligation of a T7 promoter. As the population is selectively enriched with better ligase activity, the strand displacement system allows for the monitoring of the population's ligation rate. The strand displacement reporter system permits the detection of ligated ribozyme. Once ligated with the T7 promoter, the 5' end of the ribozyme displaces paired fluorophore-quencher oligonucleotides, in turn, generating visible signal upon UV light excitation. As the ligation rate of the population increases, due to the selection for faster ligating species, the fluorescent signal develops more rapidly. The pairing of the continuous isothermal system with the fluorescent reporting scheme allows any user, provided with minimal materials, to model the continuous directed evolution of a biomolecule., (Copyright © 2013 Wiley-Liss, Inc.)

Intracellular folate homeostasis and metabolism is regulated by numerous genes. Among them, 5,10-methylenetetrahydrofolate reductase (MTHFR) is of special interest because of its involvement in regulation of the homocysteine level in the body as a result of folate metabolism. Moreover, some studies demonstrated that the homocysteine plasma level in individuals may be influenced by polymorphisms present in the MTHFR gene. Two common, clinically relevant mutations have been described: MTHFR C677T and MTHFR A1298C. Although several laboratory techniques allow genotyping of both polymorphisms, PCR-RFLP analysis is simple to perform, relatively cheap, and thus one of the most utilized. In the case of A1298C, the PCR-RFLP technique that utilizes MboII endonuclease class II requires an acrylamide gel electrophoresis, since agarose gel electrophoresis is unable to resolve short deoxyribonucleic acid (DNA) fragments after restriction digestion. Agarose gel electrophoresis is commonly preferred over that of acrylamide. To resolve this inconvenience, a novel PCR-RFLP, AjuI-based method to genotype A1298C alleles has been developed that can be performed on standard agarose gel.

The genotype-phenotype relation is at the core of theoretical biology. It is argued why a mathematically based explanatory structure of this relation is in principle possible, and why it has to embrace both sequence to consequence and consequence to sequence phenomena. It is suggested that the primary role of DNA in the chain of causality is that its presence allows a living system to induce perturbations of its own dynamics as a function of its own system state or phenome, i.e. it capacitates living systems to self-transcend beyond those morphogenetic limits that exist for non-living open physical systems in general. Dynamic models bridging genotypes with phenotypic variation in a causally cohesive way are shown to provide explanations of genetic phenomena that go well beyond the explanatory domains of statistically oriented genetics theory construction. A theory originally proposed by Rupert Riedl, which implies that the morphospace that is reachable by the standing genetic variation in a population is quite restricted due to systemic constraints, is shown to provide a foundation for a mathematical conceptualization of numerous evolutionary phenomena associated with the phenotypic consequence to sequence relation. The paper may be considered a call to arms to mathematicians and the mathematically inclined to rise to the challenge of developing new formalisms capable of dealing with the deep defining characteristics of living systems., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

HLA typing by sequence-specific primers (PCR-SSP) is a commonly used technique in HLA typing in which multiple pairs of cis-located allele-specific primers are used to determine the alleles present in a given DNA sample. Although the technique is around two decades old, it still offers a relatively straight forward way of typing and has the benefit of using commonly available laboratory equipment. Here we describe the background of the PCR-SSP, how to design and validate reactions, and common problems that arise.

One of the key questions of biology is the nature and mechanisms of gene function. It has been 60 years since proposing the right-handed model of DNA double helix in 1953. This discovery was honored with Nobel Prize in 1962 and become a breakthrough in knowing and understanding mechanisms of heredity and genetic code. Since that time a great deal of data have been gathered considering functions, structure and DNA application. It became the basis of modern molecular biology, chemical biology and biotechnology. Today we know, that double helix is characterized by its dynamics and plasticity, which depend on its nucleotide sequence. Chromatin structure and DNA mediated charge transport have a crucial role in understanding mechanisms of its damage and repair. Progress in epigenetics allowed to identify new DNA bases, such as 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxycytosine. Design of new catalytic nucleic acids and the nanotechnology field of DNA origami reveal its application potential.

Maize Activator (Ac) is one of the prototype transposable elements of the hAT transposon superfamily, members of which were identified in plants, fungi, and animals. The autonomous Ac and nonautonomous Dissociation (Ds) elements are mobilized by the single transposase protein encoded by Ac. To date Ac/Ds transposons were shown to be functional in approximately 20 plant species and have become the most widely used transposable elements for gene tagging and functional genomics approaches in plants. In this chapter we review the biology, regulation, and transposition mechanism of Ac/Ds elements in maize and heterologous plants. We discuss the parameters that are known to influence the functionality and transposition efficiency of Ac/Ds transposons and need to be considered when designing Ac transposase expression constructs and Ds elements for application in heterologous plant species.

DNA extraction from microdissected cells has become essential for handling clinical specimens with advances in molecular pathology. Conventional methods have limitations for extracting amplifiable DNA from specimens containing a small number of cells. We developed an ammonium sulfate DNA extraction method (A) and compared it with two other methods (B and C). DNA quality and quantity, β-globin amplification, and detectability of two cancer associated gene mutations were evaluated. Method A showed the best DNA yield, particularly when the cell number was very low. Amplification of the β-globin gene using DNA from the SNU 790 cell line and papillary thyroid carcinoma (PTC) cells extracted with Method A demonstrated the strongest band. BRAF(V600E) mutation analysis using ethanol-fixed PTC cells from a patient demonstrated both a "T" peak increase and an adjacent "A" peak decrease when 25 and 50 cells were extracted, whereas mutant peaks were too low to be analyzed using the other two methods. EGFR mutation analysis using formalin-fixed paraffin-embedded lung cancer tissues demonstrated a mutant peak with Method A, whereas the mutant peak was undetectable with Methods B or C. Method A yielded the best DNA quantity and quality with outstanding efficiency, particularly when paucicellular specimens were used.

The Prkar1b gene encodes regulatory type 1 beta subunit of protein kinase A. Here we report that mouse R1β gene produces three alternative splice variants (designated as mR1β1, mR1β2 and mR1β3) that have different N-terminal protein structures. New splice variants were identified using combinatorial approach of bioinformatics pipeline involving online available tools and databases, and molecular biology techniques involving RT-PCR, semi-nested PCR and sequencing. Except mR1β3, which was not detected by RT-PCR in brain and muscle tissues of 3day old mice, all three spliced isoforms were found to be ubiquitously expressed in tissues and postnatal developmental stages examined. The presence of different N-termini in isoforms may be important for unique docking interactions with A kinase anchoring proteins., (Copyright © 2012 Elsevier B.V. All rights reserved.)

This protocol describes a rapid, precise method for generating sets of embryonic stem (ES) cells or mouse embryonic fibroblasts (MEFs) harboring point mutations in the p53 tumor suppressor gene (officially known as Trp53). The strategy uses cells from the Trp53 (p53-null) 'platform' mouse, which allows site-specific integration of plasmid DNA into the Trp53 locus. Simple PCR protocols identify correctly targeted clones and immunoblots verify re-expression of the protein. We also present protocol modifications needed for efficient recovery of MEF clones expressing p53 constructs that retain wild-type function, including growth at low (3%) oxygen and transient downregulation of p53 regulators to forestall cell senescence of primary MEFs. A library of cell lines expressing various p53 mutants derived from the same population of primary fibroblasts or platform ES cells can be acquired and screened in less than 1 month.

A number of molecular biology techniques are available to generate variants from a particular start gene for eventual protein expression. We discuss the basic principles of these methods in a repertoire that may be used to achieve the elemental steps in protein engineering. These include site-directed, deletion and insertion mutagenesis. We provide detailed case studies, drawn from our own experiences, packaged together with conceptual discussions and include an analysis of the techniques presented with regards to their uses in protein engineering.

RNA silencing has been exploited to produce transgenic plants with resistance to viral pathogens via posttranscriptional gene silencing (PTGS). In some cases, this technology is difficult to apply due to the instability of inverted repeat (IR) constructs during cloning and plant transformation. Although such constructs have been shown to be stabilized with introns and efficiently induce RNA silencing, we found that the Pdk intron did not stabilize South African cassava mosaic virus (SACMV) silencing constructs. Therefore, we developed a method for producing long SACMV IR constructs through bisulfite-induced base pair mismatches on the sense arm prior to IR assembly. Expression of SACMV BC1 mismatched IR constructs in the model test plant Nicotiana benthamiana resulted in a reduction in viral BC1 transcript levels, hence viral replication, upon SACMV infection. Mismatched SACMV AC1 IR constructs induced PTGS more efficiently in a N. benthamiana callus system than nonmismatched IR constructs. Our novel method for IR construct generation should be applicable to many sequences where the generation of these constructs has proven difficult in the past.

Bisulfite genomic sequencing provides a single-molecule view of cytosine methylation states. After deamination, each cloned molecule contains a record of methylation within its sequence. The full power of this technique is harnessed by treating nuclei with an exogenous DNMT prior to DNA extraction. This exogenous methylation marks regions of accessibility and footprints nucleosomes, as well as other DNA-binding proteins. Thus, each cloned molecule records not only the endogenous methylation present (at CG sites, in mammals), but also the exogenous (GC, when using the Chlorella virus protein M.CviPI). We term this technique MAPit, methylation accessibility protocol for individual templates.

Site-specific recombinases have been harnessed for a variety of genetic manipulations involving the gain, loss, or rearrangement of genomic DNA in a variety of organisms. The enzymes have been further exploited in the model eukaryote Saccharomyces cerevisiae for mechanistic studies involving chromosomal context. In these cases, a chromosomal element of interest is converted into a DNA circle within living cells, thereby uncoupling the element from neighboring regulatory sequences, obligatory chromosomal events, and other context-dependent effects that could alter or mask intrinsic functions of the element. In this chapter, I discuss general considerations in using site-specific recombination to create DNA circles in yeast and the specific application of the R recombinase.

Immunizing a camelid (camels and llamas) with soluble, properly folded proteins raises an affinity-matured immune response in the unique camelid heavy-chain only antibodies (HCAbs). The peripheral blood lymphocytes of the immunized animal are used to clone the antigen-binding antibody fragment from the HCAbs in a phage display vector. A representative aliquot of the library of these antigen-binding fragments is used to retrieve single domain antigen-specific binders by successive rounds of panning. These single domain antibody fragments are cloned in tandem to generate manifold constructs (bivalent, biparatopic or bispecific constructs) to increase their functional affinity, to increase specificity, or to connect two independent antigen molecules.

A vast body of evidence in the literature indicates that nucleosomes can act as barriers to transcriptional initiation. The nucleosome at the promoter inhibits association of transcription factors disallowing active transcription of the gene. We have found a nucleosome on tobacco pathogenesis-related gene-1a (PR-1a) core promoter and mapped its boundaries and extension to find its span. The nucleosome covers the TATA box and Inr region of the core promoter and gets disassembled upon induction. Prior to its removal, modifications (i.e., acetylation and methylation of histones) occur at the nucleosome, proving a role of epigenetic modifications in transcriptional regulation. We summarize here various methodologies to analyze promoter chromatin structure in plants using the PR-1a core promoter as an example.

We overexpressed and purified enzymes involved in the pyrimidine catabolic pathway in the yeast Saccharomyces (Lachancea) kluyveri. A new vector was therefore designed, providing the first specific expression system in Saccharomyces kluyveri. The URC1 gene was overexpressed and a soluble protein obtained and successfully purified using the C-terminally added His-tag. Our system will be used for further studies of the structure and function of the enzymes belonging to the URC pyrimidine degradation pathway.

Dengue virus RNA purification from human plasma is useful for research and clinical purposes. Dengue is endemic in the Espirito Santo State, Brazil, and it is progressively becoming a hard-to-control public health problem. Dengue virus types 1, 2 and 3 are currently found in Brazilian territory, and recently Dengue virus type 4 has been reported to enter Brazilian borders. This virus spreads rapidly during epidemic outbreaks, and thousands of patients are infected annually, with an underestimated number of deaths in consequence of hemorrhagic Dengue. Because this disease affects mainly developing countries, it is imperative that a robust, rapid and low cost method for viral nucleic acid purification is found. In this manuscript we compare two RNA extraction methods from serum/plasma of patients with clinical diagnosis of dengue. The QIAamp(®) UltraSens Virus Kit (Qiagen Inc., Valencia, USA) and the less expensive Chomczynski-Sacchi method were used to analyze a total of 47 samples. After nucleic acid purification, reverse transcription and polymerase chain reaction amplification with dengue virus type 2 specific primers were performed. This subtype is the most prevalent in our geographical location. Thirty-four samples were positive when RNA was extracted by the Chomczynski-Sacchi technique, whereas only 27 of these were positive when the QIAamp(®) UltraSens Virus Kit was used. These results favor the utilization of the more affordable technique for the purification of viral RNA, which is especially important for developing countries.

A suite of protein fusion vectors is presented that has been designed so that nine separate fusion vectors can be constructed from one PCR product using InFusion™ cloning. These vectors in combination with a small scale Escherichia coli expression screen can be used to assess in parallel the effect of fusion tags on solubility. The vectors were tested with 20 target proteins and the results suggest that the vectors are useful both as a rescue strategy if the N-terminal hexa-histidine tagged construct does not express and also as part of a primary expression experiment., (Copyright © 2011 Elsevier Inc. All rights reserved.)