Measuring Practical Reversibility of Surface-Bound DNA for Mechanistic Insight into Folding-Based Sensors

In this paper, we characterize the mass-transport-limited response of surface-tethered redox moieties via flexible DNA linkers using measured voltammetric peak current and peak potential splitting. We demonstrate that peak splitting can be used to differentiate between reversible, quasi-reversible, and irreversible electrochemical regimes of the tethered redox molecule. Interestingly, the transition from one regime to another is dependent on the length and structure of the DNA probe. For example, as the probe length increases the transition from reversible to quasi-reversible occurs at lower scan rates. Additionally, we directly compare the dependence of the peak splitting and peak current as a function of scan rate for ssDNA, dsDNA, and other structured nucleic acids such as stem-loop and pseudoknot probes. Lastly, we find that by interrogating our surfaces with cyclic voltammetry we can observe quantitative differences in the peak splitting once the aptamer is in a bound state and correlate this to the extent of conformational change the sequence undergoes. The observations reported herein are consistent with the postulation that signaling in this class of sensor architectures is dictated by changes in nucleic acid structure and flexibility, which controls the mass transfer rate of the redox probe to the surface of the electrode.

Utilization of Biotechnology, Neurotransmitter and Cytogenetic Indices in Selecting Pigeon Breeds

The DNA polymorphism LDH-A and DRD4 gene, some neurotransmitter and cytogenetic indices of three sexed pigeon breeds; non-racing pigeons (wild rock), racing long and short distances pigeons (e.g: Gan aarden) and (e.g: Gansen) have been performed. The long-distance pigeon demonstrated the highest levels of neurotransmitters in brain tissues. Long distance male pigeons have a unique LDH-A polymorphism, so A changed to G, which means that changes in gene expression resulted in differences in amino acid structure K(lys) was converted to E(glu) in the LDH-A gene only in long distance male pigeons compared to other breeds. In addition to this, the DRD4 polymorphism of long distance male pigeons in which A changed to C and A changed to T indicates the presence of a unique diversity in this breed. This means that changes in gene expression resulted in overall amino acid structure differences only in long distance male pigeons when compared to other breeds, where R(arg) and L(leu) were converted to S(ser) and F(phe). Neurotransmitters are synthesised in the body from these amino acids. It concluded that measurements would be useful indices for the differentiation, genetic characterization, provide a foundation for conservation programs of the breeding and selecting racing pigeon breeders.

Beyond G-Quadruplexes—The Effect of Junction with Additional Structural Motifs on Aptamers Properties

G-quadruplexes constitute an important type of nucleic acid structure, which can be found in living cells and applied by cell machinery as pivotal regulatory elements. Importantly, robust development of SELEX technology and modern, nucleic acid-based therapeutic strategies targeted towards various molecules have also revealed a large group of potent aptamers whose structures are grounded in G-quadruplexes. In this review, we analyze further extension of tetraplexes by additional structural elements and investigate whether G-quadruplex junctions with duplex, hairpin, triplex, or second G-quadruplex motifs are favorable for aptamers stability and biological activity. Furthermore, we indicate the specific and pivotal role of the G-quadruplex domain and the additional structural elements in interactions with target molecules. Finally, we consider the potency of G-quadruplex junctions in future applications and indicate the emerging research area that is still waiting for development to obtain highly specific and effective nucleic acid-based molecular tools.

Phosphorylation and Fragmentation of the Cardiac Troponin T: Mechanisms, Role in Pathophysiology and Laboratory Diagnosis

Cardiac troponin T (cTnT), a protein essential for calcium-regulated, myofibrillar ATPase activity, is extremely sensitive to the action of a significant number of intra- and extracellular enzymes, the action of which causes post-translational modifications (PTMs) of amino acid structure and functioning cTnT. PTMs of cTnT may play important roles in the regulation of cardiac contractility. The vast majority of cTnT modifications involve the phosphorylation by a variety of Ser/Thr kinases, including PKC. At the same time, the activity of cTnT phosphorylation can change under physiological conditions and in some CVDs, including HF, AMI, and arrhythmias. Along with cTnT phosphorylation, cTnT fragmentation occurs, the activity of which can also change. This article discusses the mechanisms of cTnT phosphorylation and fragmentation, discusses the important role of these processes in the pathophysiology and laboratory diagnosis of some CVD, and notes promising directions for further research.

(Dys)function Follows Form: Nucleic Acid Structure, Repeat Expansion, and Disease Pathology in FMR1 Disorders

Fragile X-related disorders (FXDs), also known as FMR1 disorders, are examples of repeat expansion diseases (REDs), clinical conditions that arise from an increase in the number of repeats in a disease-specific microsatellite. In the case of FXDs, the repeat unit is CGG/CCG and the repeat tract is located in the 5′ UTR of the X-linked FMR1 gene. Expansion can result in neurodegeneration, ovarian dysfunction, or intellectual disability depending on the number of repeats in the expanded allele. A growing body of evidence suggests that the mutational mechanisms responsible for many REDs share several common features. It is also increasingly apparent that in some of these diseases the pathologic consequences of expansion may arise in similar ways. It has long been known that many of the disease-associated repeats form unusual DNA and RNA structures. This review will focus on what is known about these structures, the proteins with which they interact, and how they may be related to the causative mutation and disease pathology in the FMR1 disorders.

Effect of dehydration and butter-frying on chinicuil (Comadia redtenbacheri Hammershmidt) and maguey white worm (Aegiale hesperiaris Walker)

In the state of Hidalgo, México, chinicuil (CH) and maguey white worm (MW) are consumed as well as used in different culinary preparations. Few studies are available on the effect of butter-frying (BF) and dehydration (DN) on their chemical composition. The objective of this study was to compare the effect of DN and BF on the chemical composition and fatty acids (FA) content of CH and MW. CH and MW were purchased and then fried in butter. The fresh samples were dehydrated at 70 °C for 4 h, and their chemical analysis was performed. The Soxhlet method was used for the extraction of oils (DNCH, DNMW, BFCH, and BFMW), which were analysed with regard to the quality parameters (i.e. moisture, acidity, iodine, and peroxide). The FA contents were determined by gas chromatography coupled with mass spectrometer. The DNCH (72.82%) and DNMW (76.81%), revealed high concentrations of saturated FA. Free FA and hydro-peroxides were produced, which affected the percentage of saturated FA in the BFCH (15%) and BFMW (17%) samples, and unsaturated FA by 85 and 84%, respectively, along with the production of trans-FA. Therefore, it is necessary to regulate the frying conditions, as BF causes harmful changes in their chemical composition and in their fatty acid structure, in CH and MW, which can cause health problems to humans.

Isolation and Identification of two Triterpenoids from Ethyl acetate extract of Bark of Boehmeria rugulosa

Column chromatography of purified ethyl acetate extract of bark part of Boehmeria rugulosa afforded triterpenoids (3-oxo-20-demethylisoaleuritolic-28,29-dioic acid and 3-oxo-20-demethylisoaleuritolic-28,30-dioic acid.). Structure of these compounds was elucidated using spectroscopic techniques. This is the first report of isolation of this compound from bark of B. rugulosa.

Polyunsaturated fatty acid structure determines the strength of potentiation of Acid-sensing ion channels

Acid-sensing ion channels (ASICs) are thought to be endogenous sensors of acidic pain in inflammatory pathways. It has previously been demonstrated that arachidonic acid (AA), a pain and inflammation promoting molecule, potentiates ASICs. However, a mechanistic understanding of how AA regulates ASICs is lacking. Furthermore, little is known regarding modulation by other polyunsaturated fatty acids (PUFAs). Here we show that PUFAs stabilize the open state of the channel by shifting the pH dependence of activation to more alkaline values, increasing max conductance, and slowing channel desensitization. We examine the effects of 35 PUFAs/PUFA derivatives and show that ASICs can be more strongly potentiated by these lipids than was originally seen for AA. In fact, arachidonoyl glycine (AG) can act as a ligand and activate the channel in the absence of acidic pH. We find that the strength of potentiation is critically dependent upon a negatively charged PUFA head group as well as both the length and the number of doubles bonds in the acyl tail. PUFA-induced shifts in the pH dependence of activation could be eliminated upon mutation of a highly conserved, positively charged arginine in the outer segment of TM1 (R64). Combined our results suggest a hypothesis whereby an electrostatic interaction between the charged PUFA head group and the positively charged arginine side chain potentiates ASIC currents by stabilizing the open state of the channel. This work uncovers a novel putative lipid binding site on ASICs and provides the structural basis for future development of compounds targeting ASICs.