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Small non-coding RNAs (sRNAs) are important players of gene expression regulation in bacterial pathogens. MtvR is a 136-nucleotide long sRNA previously identified in the human pathogen Burkholderia cenocepacia J2315 and with homologues restricted to bacteria of the Burkholderia cepacia complex. In this work we have investigated the effects of expressing MtvR in Escherichia coli and Pseudomonas aeruginosa. Results are presented showing that MtvR negatively regulates the hfq mRNA levels in both bacterial species. In the case of E. coli, this negative regulation is shown to involve binding of MtvR to the 5′-UTR region of the hfqEc mRNA. Results presented also show that expression of MtvR in E. coli and P. aeruginosa originates multiple phenotypes, including reduced resistance to selected stresses, biofilm formation ability, and increased susceptibility to various antibiotics. [ABSTRACT FROM AUTHOR]

We report DNA binding studies ofthe dinuclear ruthenium ligand[{Ru(phen)2}2tpphz]4+in enantiomericallypure forms. As expected from previous studies of related complexes,both isomers bind with similar affinity to B-DNA and have enhancedluminescence. However, when tested against the G-quadruplex from humantelomeres (which we show to form an antiparallel basket structurewith a diagonal loop across one end), the ΛΛ isomer bindsapproximately 40 times more tightly than the ΔΔ, witha stronger luminescence. NMR studies show that the complex binds atboth ends of the quadruplex. Modeling studies, based on experimentallyderived restraints obtained for the closely related [{Ru(bipy)2}2tpphz]4+, show that the ΛΛisomer fits neatly under the diagonal loop, whereas the ΔΔisomer is unable to bind here and binds at the lateral loop end. Moleculardynamics simulations show that the ΔΔ isomer is preventedfrom binding under the diagonal loop by the rigidity of the loop.We thus present a novel enantioselective binding substrate for antiparallelbasket G-quadruplexes, with features that make it a useful tool forquadruplex studies. [ABSTRACT FROM AUTHOR]

We studied the effect of using different heme group chargeparametrizationmethods and schemes (Merz–Kollman, CHELPG, and single- andmulticonformational RESP) on the quality of the results produced bythe constant-(pH,E) MD method, applied to the redoxtitration of Desulfovibrio vulgarisHildenborough cytochrome c3. These newand more accurate charge sets enabled us to overcome the previouslyreported dependence of the method’s performance on the dielectricconstant, ε, assigned to the protein region. In particular,we found a systematic, clear shift of the Emodtoward more negative values than those previously reported, in agreementwith an electrostatics based reasoning. The simulations showed strongcoupling between protonating/redox sites. We were also able to capturesignificant direct and, especially, indirect interactions betweenhemes, such as those mediated by histidine 67. Our results highlightthe importance of having a good quantum description of the systembefore deriving atomic partial charges for classic force fields. [ABSTRACT FROM AUTHOR]

A series of nine new complexes incorporating [RuIICl([n]aneS3)] (n = 12, 14, 16) metal centers bridged by three ditopic ligands containing two monodentate sites (pyrazine, 4,4'-bipyridine, and 3,6-bis(4-pyridyl)-1 ,2,4,5-tetrazine) have been synthesized and fully characterized. The solid-state structures of three of the complexes have been further characterized by X-ray crystallography studies. Intermetallic interactions within the new systems have been probed using electrochemistry and optical spectroscopy. Cyclic voltammetry reveals that the three pyrazine bridged systems display two separate RuIII/III redox couples. Using spectroelectrochemistry, we have investigated the optical properties of these mixed valence, Creutz-Taube ion analogues. An analysis of the intervalence charge transfer bands for the complexes revealed that, despite possessing the same donor sets, the electronic delocalization within these systems is modulated by the nature of the coordinated thiacrown. Computational modeling using density function theory offers further evidence of interaction between metal centers and provides insights into how these interactions are mediated. [ABSTRACT FROM AUTHOR]

Abstract: DFT and TD-DFT calculations (ADF program) were performed in order to analyze the electronic structure of the [M3(CO)12] clusters (M=Ru, Os) and interpret their electronic spectra. The highest occupied molecular orbitals are M–M bonding (σ) involving different M–M bonds, both for Ru and Os. They participate in low-energy excitation processes and their depopulation should weaken M–M bonds in general. While the LUMO is M–M and M–CO anti-bonding (σ*), the next, higher-lying empty orbitals have a main contribution from CO (π*) and either a small (Ru) or an almost negligible one (Os) from the metal atoms. The main difference between the two clusters comes from the different nature of these low-energy unoccupied orbitals that have a larger metal contribution in the case of ruthenium. The photochemical reactivity of the two clusters is reexamined and compared to earlier interpretations. To cite this article: M.J. Calhorda et al., C. R. Chimie 8 (2005) . [Copyright &y& Elsevier]

Sulfate templation has been used in the synthesis of a novel tris-urea-based triply interlocked capsule, whose structure has been verified by DOSY NMR, mass spectrometry and molecular modelling investigations. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is a disease that plagues the frailest members of society. We have developed a family of N-alkyl nitrobenzamides that exhibit promising antitubercular activities and can be considered a structural simplification of known inhibitors of decaprenylphosphoryl-β-D-ribofuranose 2′-oxidase (DprE1), an essential Mycobacterium tuberculosis (Mtb) enzyme and an emergent antitubercular target. Hereby, we report the development of these compounds via a simple synthetic methodology as well as their stability, cytotoxicity, and antitubercular activity. Studying their in vitro activity revealed that the 3,5-dinitro and the 3-nitro-5-trifluoromethyl derivatives were the most active, and within these, the derivatives with intermediate lipophilicities presented the best activities (MIC of 16 ng/mL). Additionally, in an ex vivo macrophage model of infection, the derivatives with chain lengths of six and twelve carbon atoms presented the best results, exhibiting activity profiles comparable to isoniazid. Although the proof is not definite, the assessment of susceptibility over multiple mycobacterial species, together with the structure similarities with known inhibitors of this enzyme, support DprE1 as a likely target of action for the compounds. This idea is also reinforced by the docking studies, where the fit of our more active compounds to the DprE1 binding pocket is very similar to what was observed for known inhibitors like DNB1. [ABSTRACT FROM AUTHOR]

Empirical force field methods typically rely on point charges to describe the electrostatic interactions, which is problematic when anisotropy needs to be considered, as in the case of the electrostatic potential of covalently bound halogens that possess a positive site, termed σ -hole, surrounded by a large negative belt. To address this, an off-center point charge (extra point, EP) is usually placed at a given distance from the halogen to emulate the σ -hole and commonly used implementations are based on the restrained electrostatic potential (RESP) procedure to fit atomic charges, being one of the most used charge models. In this context, no specific Merz–Singh–Kollman (MK) radius for iodine is available in the literature, which is an essential parameter in the RESP fitting procedure. In this work, we explored the impact of the iodine MK radius on the obtained RESP charges for a set of 12 iodinated molecules. We verified that the relative root mean square (RRMS) values obtained with and without an EP kept decreasing with increasing radii for most compounds, thus impairing optimization using such a procedure. Nevertheless, the use of an iodine MK radius lower than 2 Å is not advisable since the RRMS kept decreasing considerably until this value was reached. Moreover, the performance of three iodine MK radii was studied with the estimation of the free energy of hydration (Δ G hyd) values using alchemical free energy calculations, which are particularly sensitive to the charges used. Despite the usage of different radii not leading to remarkable differences, our results indicate that using a value of 2.70 Å leads to lower mean absolute errors (MAE) and root mean squared error (RMSE) values when comparing the calculated with the experimental Δ G hyd values. Restrained Electrostatic Potential (RESP) charges are commonly used in force fields and Merz-Singh-Kollman (MK) radii are needed in the fitting. Since iodine radius is not available, in this work, we explored the impact of changing the iodine MK radius on the RESP charges of a set of 12 iodinated molecules and their hydration free energy predictions. Our results indicate that, although the changes are small, a value of 2.70 Angstrom leads to a better agreement with experimental values. [ABSTRACT FROM AUTHOR]

[Display omitted] • First method for the synthesis of α-hydroxyphosphonates catalyzed by ruthenium(II) complexes. • High scope and chemoselectivity. • CpRu(II) complexes are efficient catalysts for C-P bond formation- Mechanism studies performed by DFT calculations. • The catalyst [CpRu(PPh 3) 2 Cl] can be used for at least 12 catalytic cycles with excellent activity. This work reports the first method for the synthesis of α-hydroxyphosphonates from aldehydes catalyzed by cyclopentadienyl ruthenium(II) complexes. The best results were obtained using the system HP(O)(OEt) 2 /[RuClCp(PPh 3) 2 ] (5 mol%), affording the α-hydroxyphosphonates in good to excellent yields with high chemoselectivity. The catalyst [RuClCp(PPh 3) 2 ] can be used for at least 12 catalytic cycles with excellent activity and the reactions were carried out under solvent free conditions. DFT calculations were performed to rationalize the mechanism showing that the barriers associated with the H-phosphonate tautomer, HP(O)(OR) 2 are unrealistically high. This led us to propose that the catalyst promotes the tautomerization towards phosphite, P(OH)(OR) 2 , via P-atom coordination, which accounts for the observed reactivity. [ABSTRACT FROM AUTHOR]

The gold(I)thiolate complexes [Au(2-SC6H4NH2)(PPh3)] (1), [PPN][Au(2-SC6H4NH2)2] (2) (PPN = PPh3=N=PPh3), and [{Au(2-SC6H4NH2)}2(μ-dppm)] (3) (dppm = PPh2CH2PPh2) have been prepared by reaction of acetylacetonato gold(I) precursors with 2-aminobenzenethiol in the appropriate molar ratio. All products are intensely photoluminescent at 77 K. The molecular structure of the dinuclear derivative 3 displays a gold-gold intramolecular contact of 3.1346-(4) Å. Further reaction with the organometallic gold(III) complex [Au(C6F5)3(tht)] affords dinuclear or tetranuclear mixed gold(I)-gold(II) derivatives with a thiolate bridge, namely, [(AuPPh3){Au(C6F5)3}(μ2-2-SC6H4NH2)] (4) and [(C6F5)3Au(μ2-2-SC6H4NH2)(AudppmAu)( μ2-2-SC6H4NH2)Au(C6F5)3] (5). X-ray diffraction studies of the latter show a shortening of the intramolecular gold(I)-gold(I) contact [2.9353(7) or 2.9332(7) Å for a second independent molecule], and short gold(I)-gold(III) distances of 3.2812(7) and 3.3822(7) Å [or 3.2923(7) and 3.4052(7) Å] are also displayed. Despite the gold-gold interactions, the mixed derivatives are nonemissive compounds. Therefore, the complexes were studied by DFT methods. The HOMOs and LUMOs for gold(I) derivatives 1 and 3 are mainly centered on the thiolate and phosphine (or the second thiolate for complex 2), respectively, with some gold contributions, whereas the LUMO for derivative 4 is more centered on the gold(III) fragment. TD-DFT results show a good agreement with the experimental UV-vis absorption and excitation spectra. The excitations can be assigned as a S ↵ Au-P charge transfer with some mixture of LLCT for derivative 1, an LLCT mixed with ILCT for derivative 2, and a S ↵ Au⋯Au-P charge transfer with LLCT and MC for derivative 3. An LMCT (thiolate ↵ AuIII mixed with thiolate ↵ Au-P) excitation was found for derivative 4. The differing nature of the excited states [participation of the gold(III) fragment and the small contribution of sulfur] is proposed to be responsible for quenching the luminescence. [ABSTRACT FROM AUTHOR]

A comparative analysis was conducted to examine the flow characteristics of two HPMC grades and their fractions. Excipients processing contains critical steps in the manufacturing of solid dosage forms and therefore it is essential to determine their flowability. Flow characterization was done using conventional and shear cell methods. After the division into different particles size, HPMC2910 showed an increase of the ff c for the fractions with the largest particle size and HPMC2208 showed an unprecedented result for the fraction with the smallest size. Thus, for this excipient, the best ff c was obtained with the fraction containing the smallest particles which surprisingly contradicted the literature (shape effect overlapped the size effect). It was also found for different fractions that the ff c increased with the increasing of the σ 1 , showing in some of them a decrease of the same from a certain σ 1 value. Furthermore, caking was not observed in both cases. [Display omitted] • Excipients flow characterization is a critical step in the pharmaceutical development. • Particle shape and size can have an additive or contradictory effect on powder flow. • The shear cell method provides results more rigorous and reliable. • Flow index (ff c) depends on the particle size and shape. • The decreased of particle size does not always worsen the powder flow. [ABSTRACT FROM AUTHOR]

Oral mucositis, a common inflammatory side effect of oncological treatments, is a disorder of the oral mucosa that can cause painful ulcerations, local motor disabilities, and an increased risk of infections. Due to the discomfort it produces and the associated health risks, it can lead to cancer treatment restrains, such as the need for dose reduction, cycle delays or abandonment. Current mucositis management has low efficiency in prevention and treatment. A topical drug application for a local action can be a more effective approach than systemic routes when addressing oral cavity pathologies. Local delivery of growth factors, antibodies, and anti-inflammatory cytokines have shown promising results. However, due to the peptide and protein nature of these novel agents, and the several anatomic, physiological and environmental challenges of the oral cavity, their local action might be limited when using traditional delivering systems. This review is an awareness of the issues and strategies in the local delivery of macromolecules for the management of oral mucositis. [ABSTRACT FROM AUTHOR]

The 21st annual meeting of the Portuguese Society of Human Genetics (SPGH), organized by Luísa Romão, Ana Sousa and Rosário Pinto Leite, was held in Caparica, Portugal, from the 16th to the 18th of November 2017. Having entered an era in which personalized medicine is emerging as a paradigm for disease diagnosis, treatment and prevention, the program of this meeting intended to include lectures by leading national and international scientists presenting exceptional findings on the genetics of personalized medicine. Various topics were discussed, including cancer genetics, transcriptome dynamics and novel therapeutics for cancers and rare disorders that are designed to specifically target molecular alterations in individual patients. Several panel discussions were held to emphasize (ethical) issues associated with personalized medicine, including genetic cancer counseling. [ABSTRACT FROM AUTHOR]

A new family of copper(I) complexes of general formula [Cu(dppe)(NN)] + have been synthesized and fully characterized, with dppe = 1.2-bis(diphenylphosphino)ethane and NN representing several bidentate heteroaromatic ligands: 2,2′-bipy = 2.2′-bipyridine (1), Me 2 bpy = 4.4′-dimethyl-2,2′-bipyridine (2), dpytz = 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (3), dpp = 2.3-bis(2-pyridyl)pyrazine (4), and the metallaligand [Ru(η 5 -C 5 H 5 )(PPh 3 )(dpp)] + (5), yielding the bimetallic copper(I)-ruthenium(II) complex [Cu(dppe)(μ-dpp)Ru(η 5 -C 5 H 5 )(PPh 3 )] 2 + (6). The single crystal structures of complexes (2) and (4) were determined by X-ray diffraction studies. All the complexes exhibit high cytotoxicity against the human cancer cells A2780 and MCF7 with IC 50 values far lower than those found for the antitumor drug cisplatin in the same cell lines and even surpassing cisplatin resistance in the A2780cisR cells. They display IC 50 values on the human embryonic kidney HEK293 non-tumoral cells of the same order of magnitude as those found for the tumoral cells. In the ovarian cells the compounds induce rapid production of reactive oxygen species (ROS) probably through mitochondrial pathways. According to the results reported here, these compounds can be considered as prospective antitumoral agents that deserve further evaluation. [ABSTRACT FROM AUTHOR]

Abstract: The rigid [6]ferrocenophane, L1, was synthesised by condensation of 1,1′-ferrocene dicarbaldehyde with trans-1,2-diaminocyclohexane in high dilution at r.t. followed by reduction. When other experimental conditions were employed, the [6,6,6]ferrocenephane (L2) was also obtained. Both compounds were characterised by single crystal X-ray crystallography. The protonation of L1 and its metal complexation were evaluated by the effect on the electron-transfer process of the ferrocene (fc) unit of L1 using cyclic voltammetry (CV) and square wave voltammetry (SWV) in anhydrous CH3CN solution and in 0.1 M n Bu4NPF6 as the supporting electrolyte. The electrochemical process of L1 between −300 and 900mV is complicated by amine oxidation. On the other hand, an anodic shift from the fc/fc+ wave of L1 of 249, 225, 81 and 61mV was observed by formation of Zn2+, Ni2+, Pd2+ and Cu2+ complexes, respectively. Whereas Mg2+ and Ca2+ only have with L1 weak interactions and they promote the acid-base equilibrium of L1. This reveals that L1 is an interesting molecular redox sensor for detection of Zn2+ and Ni2+, although the kinetics of the Zn2+ complex formation is much faster than that of the Ni2+ one. The X-ray crystal structure of [PdL1Cl2] was determined and showed a square–planar environment with Pd(II) and Fe(II) centres separated by 3.781(1)Å. The experimental anodic shifts were elucidated by DFT calculations on the [ML1Cl2] series and they are related to the nature of the HOMO of these complexes and a four-electron, two-orbital interaction. [Copyright &y& Elsevier]

Abstract: The mechanism of the catalytic formation of pyridines from the coupling of two alkynes and the nitriles Nhsp sp="0.25" />=H, Me, Cl, COOMe) with the fragments CpRuCl, CpCo, and CpRh has been investigated by means of DFT/B3LYP calculations. According to the proposed mechanism, the key reaction step is the oxidative coupling of two alkyne ligands to give metallacyclopentatriene (Ru, Rh) and metallacyclopentadiene (Co) intermediates. In the case of ruthenium, this process is thermodynamically clearly favored over the oxidative coupling between one alkyne and one nitrile ligand to afford an azametallacycle. This alternative pathway however cannot be dismissed in the case of Co and Rh. The rate determining step of the overall catalytic cycle is the addition of a nitrile molecule to the metallacyclopentatriene and metallacyclopentadiene intermediates, respectively, which has to take place in a side-on fashion. Competitive alkyne addition leads to benzene formation. Thus, also the chemoselectivity of this reaction is determined at this stage of the catalytic cycle. In the case of the RuCpCl fragment, the addition of nitriles R–Ctylenes RCen studied in more detail. For R=H, Cl, and COOMe the side-on addition of nitriles is kinetically more favored than alkyne addition and, in accordance with experimental results, pyridine formation takes place. In the case of R=Me nitrile addition could not be achieved and the addition of alkynes to give benzene derivatives seems to be kinetically more favored. Once the nitrile is coordinated facile C–C bond coupling takes place to afford an unusual five- and four-membered bicyclic ring system. This intermediate eventually rearranges to a very unsymmetrical azametallaheptatriene complex which in turn provides CpRuCl(κ1-pyridine) via a reductive elimination step. Completion of the catalytic cycle is achieved by an exergonic displacement of the respective pyridine product by two acetylene molecules regenerating the bisacetylene complex. [Copyright &y& Elsevier]

Oromucosal films and tablets were developed as multifunctional biomaterials for the treatment of oral mucositis. These are intended to function as a hybrid, performing as a controlled drug delivery system and as a wound-dressing device. The dosage forms are precursors for in loco hydrogels that are activated by the saliva. An anti-inflammatory and anesthetic activity is attained from budesonide tripartite polymeric nanoparticles and lidocaine, while the polymeric network allows the protection and cicatrization of the wound. Different biomaterials and blends were investigated, focusing on the capacity to retain and resist on-site, as well as achieve a long-lasting controlled release. As the limiting factor, the choice was made according to the films' results. A polymer mix of Methocel™ K100M and Carbopol® (974P, EDT 2020, or Ultrez 10) blends were used. Overall, regrading critical factors, Carbopol® increased films' elasticity and flexibility, mucoadhesion, and the strength of the hydrogels, while higher concentrations led to thicker, more opaque, and lower strain resistance products. Whereas 974P and Ultrez 10 performed similarly, EDT 2020 led to uniformity problems and weaker films, hydrogels and bioadhesion. The optimized products were enhanced with sodium hyaluronate and drug-loaded for further characterization. Concerning the dosage form, the films' hydrogels were more resilient, while the tablets had higher mucoadhesiveness and longer swelling. Although through different networks and mechanisms, both dosage forms and grades revealed similar release profiles. A Case II time-evolving stereoselectivity for the 22R and 22S budesonide epimers was found, and Fickian-diffusion for lidocaine. Ultimately, the developed formulations show great potential to be used in OM management. Both of the selected grades at 0.6% displayed excellent performance, while Ultrez 10 can be preferable for the films' production due to its lower viscosity before neutralization and higher after activation. Where the tablets are easier to produce and offer better adhesion, the films are more customizable post-production and have higher rheological performance for wound-dressing. Unlabelled Image • Polyacrylic acid in situ neutralization in solvent-casting increases film performance. • Equal polymers in films or tables produce different hydrogels after hydration. • HPMC and polyacrylic acid balance for optimal mechanical and rheological performance. • Polymer state influences water diffusion, initial mass transfer, and holding capacity. • Evolving stereoselectivity and mechanism in the release of budesonide's epimers [ABSTRACT FROM AUTHOR]

Eukaryotic cells possess surveillance mechanisms that detect and degrade defective transcripts. Aberrant transcripts include mRNAs with a premature termination codon (PTC), targeted by the nonsense-mediated decay (NMD) pathway, and mRNAs lacking a termination codon, targeted by the nonstop decay (NSD) pathway. The eukaryotic exosome, a ribonucleolytic complex, plays a crucial role in mRNA processing and turnover through its catalytic subunits PM/Scl100 (Rrp6 in yeast), DIS3 (Rrp44 in yeast), and DIS3L1. Additionally, eukaryotic cells have other ribonucleases, such as SMG6 and XRN1, that participate in RNA surveillance. However, the specific pathways through which ribonucleases recognize and degrade mRNAs remain elusive. In this study, we characterized the involvement of human ribonucleases, both nuclear and cytoplasmic, in the mRNA surveillance mechanisms of NMD and NSD. We performed knockdowns of SMG6, PM/Scl100, XRN1, DIS3, and DIS3L1, analyzing the resulting changes in mRNA levels of selected natural NMD targets by RT-qPCR. Additionally, we examined the levels of different human β-globin variants under the same conditions: wild-type, NMD-resistant, NMD-sensitive, and NSD-sensitive. Our results demonstrate that all the studied ribonucleases are involved in the decay of certain endogenous NMD targets. Furthermore, we observed that the ribonucleases SMG6 and DIS3 contribute to the degradation of all β-globin variants, with an exception for βNS in the former case. This is also the case for PM/Scl100, which affects all β-globin variants except the NMD-sensitive variants. In contrast, DIS3L1 and XRN1 show specificity for β-globin WT and NMD-resistant variants. These findings suggest that eukaryotic ribonucleases are target-specific rather than pathway-specific. In addition, our data suggest that ribonucleases play broader roles in mRNA surveillance and degradation mechanisms beyond just NMD and NSD.

In this work, we investigated the anticancer activity of several novel silver(I) 2,2'-bipyridine complexes containing either triphenylphosphane (PPh 3 ) or 1,2-bis(diphenylphosphino)ethane (dppe) ligands. All compounds were characterized by diverse analytical methods including ESI-MS spectrometry; NMR, UV-vis, and FTIR spectroscopies; and elemental analysis. Moreover, several compounds were also studied by X-ray single-crystal diffraction. Subsequently, the compounds were investigated for their anticancer activity against drug-resistant and -sensitive cancer cells. Noteworthily, neither carboplatin and oxaliplatin resistance nor p53 deletion impacted on their anticancer efficacy. MES - OV cells displayed exceptional hypersensitivity to the dppe-containing drugs. This effect was not based on thioredoxin reductase inhibition, enhanced drug uptake, or apoptosis induction. In contrast, dppe silver drugs induced paraptosis, a novel recently described form of programmed cell death. Together with the good tumor specificity of this compound's class, this work suggests that dppe-containing silver complexes could be interesting drug candidates for the treatment of resistant ovarian cancer.

In recent years, organometallic complexes have attracted much attention as anticancer therapeutics aiming at overcoming the limitations of platinum drugs that are currently marketed. Still, the development of half-sandwich organometallic cobalt complexes remains scarcely explored. Four new cobalt(III)-cyclopentadienyl complexes containing N,N-heteroaromatic bidentate, and phosphane ligands were synthesized and fully characterized by elemental analysis, spectroscopic techniques, and DFT methods. The cytotoxicity of all complexes was determined in vitro by the MTS assay in colorectal (HCT116), ovarian (A2780), and breast (MDA-MB-231 and MCF-7) human cancer cell lines and in a healthy human cell line (fibroblasts). The complexes showed high cytotoxicity in cancer cell lines, mostly due to ROS production, apoptosis, autophagy induction, and disruption of the mitochondrial membrane. Also, these complexes were shown to be nontoxic in vivo in an ex ovo chick embryo yolk sac membrane (YSM) assay.

Compounds containing halogens can form halogen bonds (XBs) with biological targets such as proteins and membranes due to their anisotropic electrostatic potential. To accurately describe this anisotropy, off-center point-charge (EP) models are commonly used in force field methods, allowing the description of XBs at the molecular mechanics and molecular dynamics level. Various EP implementations have been documented in the literature, and despite being efficient in reproducing protein-ligand geometries and sampling of XBs, it is unclear how well these EP models predict experimental properties such as hydration free energies (Δ G hyd ), which are often used to validate force field performance. In this work, we report the first assessment of three EP models using alchemical free energy calculations to predict Δ G hyd values. We show that describing the halogen anisotropy using some EP models can lead to a slight improvement in the prediction of the Δ G hyd when compared with the models without EP, especially for the chlorinated compounds; however, this improvement is not related to the establishment of XBs but is most likely due to the improvement of the sampling of hydrogen bonds. We also highlight the importance of the choice of the EP model, especially for the iodinated molecules, since a slight tendency to improve the prediction is observed for compounds with a larger σ-hole but significantly worse results were obtained for compounds that are weaker XB donors.

Pd(II) catalysts, particularly the acetate salt in acetic acid, tended to favor regioselective C-H activation of quinoline N-oxides (QOs) at the C2 position. However, Pd(II)Cl 2 was shown to catalyze their C-H activation at C8 and, in the presence of water, C8-H activation was accompanied by the formation of 2-quinolinones. The aim of the DFT study described in this work was to shed light on the complete mechanism of these competing catalytic reactions, when PdCl 2 reacts with QO and benzaldehyde in dichloroethane. C-H activation of QO was the first step of the reaction and involved either a metallacycle, with a C QO -Pd(II) σ-bond and a C(8)-H-Pd(II) agostic bond, or an η 3 -QO complex, with three carbon atoms of the heteroring of QO binding PdCl 2 . The first situation led to the unusual C8 activation and the second to C2 activation. The σ-metallacycle undergoes C8-H activation and the energy of the TOF determining the transition state to form the product is ∼17 kcal mol -1 , while for the reaction through the π-metallacycle (C2-H activation) the corresponding energy is higher (∼29 kcal mol -1 ) and thus is not competitive under the same conditions. The reaction proceeding through the σ-complex, activating the C8 position, is preferred, in agreement with experimental results. Both reactions involve oxidation of Pd(II) to Pd(IV) and the catalyst is regenerated. When small amounts of water are added to the reaction mixture, C8-H activation (acylation) results from the same σ-metallacycle with the same barrier, but the simultaneous formation of 2-quinolinones is more complicated. It starts with OH - attack at the C2 position, and is followed by the migration of two hydrogen atoms, and the final reductive elimination step ends with Pd(0). The higher barriers for the migration and reoxidation of Pd(0) are associated with the more demanding reaction conditions. The different reactivity of Pd(II)(OAc) 2 under analogous conditions is clarified, as it is only capable of forming the above mentioned π-complex and thus of activating the C2 position of QO. This catalyst can preferentially activate the C8-H bond under rather different conditions, including in particular acetic acid medium, as shown by other authors.

Several factors affect the passive membrane permeation of small molecules, including size, charge, pH, or the presence of specific chemical groups. Understanding these features is paramount to identifying or designing drug candidates with optimal ADMET properties and this can be achieved through experimental/knowledge-based methodologies or using computational approaches. Empirical methods often lack detailed information about the underlying molecular mechanism. In contrast, Molecular Dynamics-based approaches are a powerful strategy, providing an atomistic description of this process. This technique is continuously growing, featuring new related methodologies. In this work, the recent advances in this research area will be discussed., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Halogen bonds (XBs) have become increasingly popular over the past few years with numerous applications in catalysis, material design, anion recognition, and medicinal chemistry. To avoid a post factum rationalization of XB trends, descriptors can be tentatively employed to predict the interaction energy of potential halogen bonds. These typically comprise the electrostatic potential maximum at the tip of the halogen, V S,max , or properties based on the topological analysis of the electronic density. However, such descriptors either can only be used with confidence for specific families of halogen bonds or require intense computations and, therefore, are not particularly attractive for large datasets with diverse compounds or biochemical systems. Therefore, the development of a simple, widely applicable, and computationally cheap descriptor remains a challenge as it would facilitate the discovery of new XB applications while also improving the existing ones. Recently, the Intrinsic Bond Strength Index (IBSI) has been proposed as a new tool to evaluate any bond strength, however, it has not been extensively explored in the context of halogen bonding. In this work, we show that IBSI values linearly correlate with the interaction energy of diverse sets of closed-shell halogen-bonded complexes in the ground state, and therefore, can be used to quantitatively predict this property. Although the linear fit models that use quantum-mechanics-based electron density provided MAEs typically below 1 kcal mol -1 , this type of calculation might still be computationally heavy in large sets or systems. Therefore, we also explored the exciting possibility of using a promolecular density approach (IBSI PRO ), which only requires the geometry of the complex as an input, being computationally cheap. Surprisingly, the performance was comparable to the QM-based methods, thus opening the door for the usage of IBSI PRO as a fast, yet accurate, XB energy descriptor in large datasets but also in biomolecular systems such as protein-ligand complexes. We also show that the δ g pair descriptor emerging from the Independent Gradient Model that leads to IBSI can be seen as a term proportional to the overlapping van der Waals volume of the atoms at a given interaction distance. Overall, ISBI can be thought of as a complementary descriptor to V S,max for situations where the geometry of the complex is available and QM calculations are not feasible whereas the latter still remains a hallmark of XB descriptors.

DIS3L2 degrades different types of RNAs in an exosome-independent manner including mRNAs and several types of non-coding RNAs. DIS3L2-mediated degradation is preceded by the addition of nontemplated uridines at the 3'end of its targets by the terminal uridylyl transferases 4 and 7. Most of the literature that concerns DIS3L2 characterizes its involvement in several RNA degradation pathways, however, there is some evidence that its dysregulated activity may contribute to cancer development. In the present study, we characterize the role of DIS3L2 in human colorectal cancer (CRC). Using the public RNA datasets from The Cancer Genome Atlas (TCGA), we found higher DIS3L2 mRNA levels in CRC tissues versus normal colonic samples as well as worse prognosis in patients with high DIS3L2 expression. In addition, our RNA deep-sequencing data revealed that knockdown (KD) of DIS3L2 induces a strong transcriptomic disturbance in SW480 CRC cells. Moreover, gene ontology (GO) analysis of significant upregulated transcripts displays enrichment in mRNAs encoding proteins involved in cell cycle regulation and cancer-related pathways, which guided us to evaluate which specific hallmarks of cancer are differentially regulated by DIS3L2. To do so, we employed four CRC cell lines (HCT116, SW480, Caco-2 and HT-29) differing in their mutational background and oncogenicity. We demonstrate that depletion of DIS3L2 results in reduced cell viability of highly oncogenic SW480 and HCT116 CRC cells, but had little or no impact in the more differentiated Caco-2 and HT-29 cells. Remarkably, the mTOR signaling pathway, crucial for cell survival and growth, is downregulated after DIS3L2 KD, whereas AZGP1, an mTOR pathway inhibitor, is upregulated. Furthermore, our results indicate that depletion of DIS3L2 disturbs metastasis-associated properties, such as cell migration and invasion, only in highly oncogenic CRC cells. Our work reveals for the first time a role for DIS3L2 in sustaining CRC cell proliferation and provides evidence that this ribonuclease is required to support the viability and invasive behavior of dedifferentiated CRC cells., (© 2023. The Author(s).)

The synthesis and biological evaluation of novel guanidino sugars as isonucleoside analogs is described. 5-Guanidino xylofuranoses containing 3-O-saturated/unsaturated hydrocarbon or aromatic-containing moieties were accessed from 5-azido xylofuranoses via reduction followed by guanidinylation with N,N'-bis(tert-butoxycarbonyl)-N''-triflylguanidine. Molecules comprising novel types of isonucleosidic structures including 5-guanidino 3-O-methyl-branched N-benzyltriazole isonucleosides and a guanidinomethyltriazole 3'-O-dodecyl xylofuranos-5'-yl isonucleoside were accessed. The guanidinomethyltriazole derivative and a 3-O-dodecyl (N-Boc)guanidino xylofuranose were revealed as selective inhibitors of acetylcholinesterase (K i =22.87 and 7.49 μM, respectively). The latter also showed moderate antiproliferative effects in chronic myeloid leukemia (K562) and breast cancer (MCF-7) cells. An aminomethyltriazole 5'-isonucleoside was the most potent molecule with low micromolar GI 50 values in both cells (GI 50 =6.33 μM, 8.45 μM), similar to that of the drug 5-fluorouracil in MCF-7 cells. Moreover, the most bioactive compounds showed low toxicity in human fibroblasts, further indicating their interest as promising lead molecules., (© 2022 Wiley-VCH GmbH.)

Tau proteins are known to be mainly involved in regulation of microtubule dynamics. Besides this function, which is critical for axonal transport and signal transduction, tau proteins also have other roles in neurons. Moreover, tau proteins are turned into aggregates and consequently trigger many neurodegenerative diseases termed tauopathies, of which Alzheimer's disease (AD) is the figurehead. Such pathological aggregation processes are critical for the onset of these diseases. Among the various causes of tau protein pathogenicity, abnormal tau mRNA metabolism, expression and dysregulation of tau post-translational modifications are critical steps. Moreover, the relevance of tau function to general mRNA metabolism has been highlighted recently in tauopathies. In this review, we mainly focus on how mRNA metabolism impacts the onset and development of tauopathies. Thus, we intend to portray how mRNA metabolism of, or mediated by, tau is associated with neurodegenerative diseases.

The reaction of [{(ArNCMe) 2 CH}Al] (Ar = 2,6-di-iso-propylphenyl) with aryl methyl ethers proceeded with alumination of the sp 3 C-O bond. The selectivity of this reaction could be switched by inclusion of a catalyst. In the presence of [Pd(PCy 3 ) 2 ], chemoselective sp 2 C-O bond functionalisation was observed. Kinetic isotope experiments and DFT calculations support a catalytic pathway involving the ligand-assisted oxidative addition of the sp 2 C-O bond to a Pd-Al intermetallic complex.

The ability of some hydrogels to exhibit a phase transition or change their structure in response to stimuli has been extensively explored for drug depot formation and controlled drug release. Taking advantage of the unique features of the tumor microenvironment (TME) or externally applied triggers, several injectable stimuli-responsive hydrogels have been described as promising candidates for intratumoral drug delivery. In this review, we provide a brief overview of the TME and highlight the advantages of intratumoral administration, followed by a summary of the reported strategies to endow hydrogels with responsiveness to physical (temperature and light), chemical (pH and redox potential), or biological (enzyme) stimuli., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The interaction between human serum transferrin (hTf) and three promising organometallic Ru (II)- (η 5 -C 5 H 5 ) derived complexes, that have already shown strong in vitro cytotoxicity towards human cancer cell lines, has been investigated using fluorescence spectroscopic techniques. The results suggested that the formation of Ru-hTf systems involves a dynamic collision. The binding process occurs spontaneously (ΔG < 0), mainly driven by hydrophobic interactions. Additional docking studies show that all complexes bind preferably to a specific hydrophobic pocket in the C2-subdomain as already observed for other metal-cyclopentadienyl (MCp) complexes and are in agreement with the experimental results. With these studies we hope to contribute to the understanding of the mechanism of action of these promising cytotoxic agents, thus providing clues for a more rational design., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

The objective of this work was to analyze the flow behavior of a commonly used filler (pregelatinised starch) and the effect of two of the most used lubricants (talc and colloidal silicon dioxide). The studies were carried out according to the conventional methods (Angle of Repose, Bulk and Tapped densities and from these the Compressibility Index) and shear cell methods (Brookfield Powder Flow Tester apparatus) described in European Pharmacopeia (Ph. Eur.). The results showed some surprising and unexpected values for the flow behavior of this filler under influence of the methods and the used glidants. Regarding pure starch and mixtures containing talc, the flow behavior was similar between them and the Flow Index (ff c ) values varied between 1.8 and 4 (very cohesive and cohesive) as consolidation stress (σ 1 ) increased. In this case, the glidant effect was not observed. However, for the mixtures of starch with colloidal silicon dioxide this effect was observed providing Flow Index (ff c ) values between 2.6 and 8.9 (cohesive and easy-flowing) as consolidation stress (σ 1 ) increased. Other parameters that are also used to characterize flow properties, more specifically, within silos, chutes and hoppers, such as effective angle of internal friction (φe), effective angle of wall friction (φx), critical arching and critical rathole values, provided similar information. Based in the obtained results from all tests it can be said that the talc did not induce improvement on the starch flow behavior in the used conditions in opposition to the effect produced by colloidal silicon dioxide.HighlightsExample 1. A good flowability of powders is needed in order to be compressed/filled;Example 2. The overcome the poor flow it is usual to use glidants;Example 3. CSD improved the pregelatinised starch (Starch 1500®) flow;Example 4. Talc do not have relevant effect in the pregelatinised starch (Starch 1500®) flow;Example 5. Powder FlowTester method showed more complete and consistent results.

In force-field methods, the usage of off-center point charges, also called extra points (EPs), is a common strategy to tackle the anisotropy of the electrostatic potential of covalently bonded halogens (X), thus allowing the description of halogen bonds (XBs) at the molecular mechanics/molecular dynamics (MM/MD) level. Diverse EP implementations exist in the literature differing on the charge sets and/or the X-EP distances. Poisson-Boltzmann and surface area (PBSA) calculations can be used to obtain solvation free energies (Δ G solv ) of small molecules, often to compute binding free energies (Δ G bind ) at the MM-PBSA level. This method depends, among other parameters, on the empirical assignment of atomic radii (PB radii). Given the multiplicity of off-center point-charge models and the lack of specific PB radii for halogens compatible with such implementations, in this work, we assessed the performance of PBSA calculations for the estimation of Δ G solv values in water (Δ G hyd ), also conducting an optimization of the halogen PB radii (Cl, Br, and I) for each EP model. We not only expand the usage of EP models in the scope of the general AMBER force field (GAFF) but also provide the first optimized halogen PB radii in the context of the CHARMM general force field (CGenFF), thus contributing to improving the description of halogenated compounds in PBSA calculations.

Halogen bonds (XBs) are noncovalent interactions where halogen atoms act as electrophilic species interacting with Lewis bases. These interactions are relevant in biochemical systems being increasingly explored in drug discovery, mainly to modulate protein-ligand interactions, but are also found in engineered protein or nucleic acid systems. In this work, we report direct evidence for the existence of XBs in the context of biological membrane systems, thus expanding the scope of application of these interactions. Indeed, our molecular dynamics simulations show the presence of favorable interactions between halobenzene derivatives and both phosphate or ester oxygen acceptors from a model phospholipid bilayer, thus supporting the existence of XB-mediated phospholipid-halogen recognition phenomena influencing the membrane insertion profile of the ligands and their orientational preferences. This represents a relevant interaction, previously overlooked, eventually determining the pharmacological or toxicological activity of halogenated compounds and hence with potential implications in drug discovery and development, a place where such species account for a significant part of the chemical space. We also provide insights into a potential role for XBs in the water-to-membrane insertion of halogenated ligands as XBs are systematically observed during this process. Therefore, our data strongly suggest that, as the ubiquitous hydrogen bond, XBs should be accounted for in the development of membrane partition models.

Synthetic anion transporters are promising therapeutic agents designed to emulate the specialized role of certain transmembrane proteins that maintain the ion concentration in cells. In the last few years, besides hydrogen bonds and ion pairs, halogen bonds have also been explored to promote the association between the synthetic molecule and the anion and their subsequent transport. This interaction is due to an anisotropic charge distribution on the halogen, and therefore, modeling halogen bonds is not a trivial task using classical force field methods that typically rely on point-charge models.Herein, a computational protocol capable of dealing with halogen bonds is presented. This protocol takes advantage of the addition of an off-center particle during the charge fitting procedure, and the resulting set of charges can be used along with the classical force field parameters from GAFF or GROMOS 54A7., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

In this article, we present supportive data related to the research article "A role for DIS3L2 over natural nonsense-mediated mRNA decay targets in human cells" [1], where interpretation of the data presented here is available. Indeed, here we analyze the impact of the DIS3L2 exoribonuclease over nonsense-mediated mRNA decay (NMD)-targets. Specifically, we present data on: a) the expression of various reporter human β-globin mRNAs, monitored by Northern blot and RT-qPCR, before and after altering DIS3L2 levels in HeLa cells, and b) the gene expression levels of deregulated transcripts generated by re-analyzing publicly available data from UPF1-depleted HeLa cells that were further cross-referenced with a dataset of transcripts upregulated in DIS3L2-depleted cells. These analyses revealed that DIS3L2 regulates the levels of a subset of NMD-targets. These data can be valuable for researchers interested in the NMD mechanism., (© 2019 The Author(s).)

RNA degradation is considered a critical posttranscriptional regulatory checkpoint, maintaining the correct functioning of organisms. When a specific RNA transcript is no longer required in the cell, it is signaled for degradation through a number of highly regulated steps. Ribonucleases (or simply RNases) are key enzymes involved in the control of RNA stability. These enzymes can perform the RNA degradation alone or cooperate with other proteins in RNA degradation complexes. Important findings over the last years have shed light into eukaryotic RNA degradation by members of the RNase II/RNB family of enzymes. DIS3 enzyme belongs to this family and represents one of the catalytic subunits of the multiprotein complex exosome. This RNase has a diverse range of functions, mainly within nuclear RNA metabolism. Humans encode two other DIS3-like enzymes: DIS3L (DIS3L1) and DIS3L2. DIS3L1 also acts in association with the exosome but is strictly cytoplasmic. In contrast, DIS3L2 acts independently of the exosome and shows a distinctive preference for uridylated RNAs. These enzymes have been shown to be involved in important cellular processes, such as mitotic control, and associated with human disorders like cancer. This review shows how the impairment of function of each of these enzymes is implicated in human disease.

Nonsense-mediated mRNA decay (NMD) is a well characterized eukaryotic mRNA degradation pathway, responsible for the identification and degradation of transcripts harboring translation termination codons in premature contexts. Transcriptome-wide studies revealed that NMD is not only an mRNA surveillance pathway as initially thought, but is also a post-transcriptional regulatory mechanism of gene expression, as it fine-tunes the transcript levels of many wild-type genes. Hence, NMD contributes to the regulation of many essential biological processes, including pathophysiological mechanisms. In this chapter we discuss the importance of NMD and of its regulation to organism development and its link to the cellular stress responses, like the unfolded protein response (UPR) and the integrated stress response (ISR). Additionally, we describe how tumor cells have explored both NMD functions to promote tumorigenesis. Using published data and databases, we have also performed a network-based approach that further supports the link between NMD and these (patho) physiological processes.

Density functional theory (DFT) calculations were performed on clusters [Os 3 (CO) 10 (α-diimine)], for α-diimine = 2,2'-bipyridine (BPY), N-isopropyl 2-iminomethylpyridine (IMP), and N, N'-diisopropyl-l,4-diaza-1,3-butadiene (DAB), together with their spectroscopic study. This important family of clusters is known to convert upon irradiation with visible light into short-lived biradicals and long-lived zwitterions from a σπ* (SBLCT) excited state that has not been described accurately thus far by quantum mechanical calculations. On the basis of the combined DFT, UV-vis absorption, and resonance Raman data, the lowest-lying visible absorption band is assigned to a σ(Os1-Os3)-to-π*(α-diimine) CT transition, for α-diimine = bpy and IMP, and to a strongly delocalized σ(Os1-Os3)π*-to-σ*(Os1-Os3)π* transition for conjugated nonaromatic α-diimine = DAB. The DFT calculations rationalize the experimentally determined characteristics of this electronic transition in the studied series: (i) The corresponding absorption band is the dominant feature in the visible spectral region. (ii) The CT character of the electronic excitation declines from α-diimine = bpy to IMP and vanishes for DAB. (iii) The excitation energies decrease in the order α-diimine = DAB > BPY > IMP. (iv) The oscillator strength shrinks in the order α-diimine = DAB > IMP > BPY. Reference photoreaction quantum yields measured accurately for the formation of a cluster zwitterion from [Os 3 (CO) 10 (IMP)] in strongly coordinating pyridine demonstrate that the optical population of the lowest-energy 1 σπ* and relaxed 3 σπ* excited states in the DFT model scheme is still capable of inducing the initial homolytic Os1-Os3 σ-bond splitting, although less efficiently than the optical excitation into neighbor higher-lying electronic transitions due to a higher potential barrier for the reaction from a dissociative (σσ*) state.

Alternative pre-mRNA splicing (AS) affects gene expression as it generates proteome diversity. Nonsense-mediated mRNA decay (NMD) is a surveillance pathway that recognizes and selectively degrades mRNAs carrying premature translation-termination codons (PTCs), preventing the production of truncated proteins that could result in disease. Several studies have also implicated NMD in the regulation of steady-state levels of physiological mRNAs. In addition, it is known that several regulated AS events do not lead to generation of protein products, as they lead to transcripts that carry PTCs and thus, they are committed to NMD. Indeed, an estimated one-third of naturally occurring, alternatively spliced mRNAs is targeted for NMD, being AS coupled to NMD (AS-NMD) an efficient strategy to regulate gene expression. In this review, we will focus on how AS mechanism operates and how can be coupled to NMD to fine-tune gene expression levels. Furthermore, we will demonstrate the physiological significance of the interplay among AS and NMD in human disease, such as cancer and neurological disorders. The understanding of how AS-NMD orchestrates expression of vital genes is of utmost importance for the advance in diagnosis, prognosis and treatment of many human disorders., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The ability of a calix[4]arene derivative (CX-1), bearing four protonated NH3(+) groups located in the upper rim and aliphatic tails in the lower rim, to interact with a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) model bilayer and promote transmembrane chloride transport was investigated by molecular dynamics (MD) simulations. Unconstrained MD simulations show that the interaction of CX-1 with DOPC occurs via the NH3(+) groups, which are able to establish electrostatic interactions and multiple hydrogen bonds with the DOPC phosphate groups, while the aliphatic tails point towards the water phase (when CX-1 starts from the water phase) or to the membrane (when CX-1 is initially positioned within the bilayer). The interaction does not induce any relevant perturbation on the biophysical properties of the bilayer system (area per lipid, thickness, and hydration) apart from a systematic increase in the order parameter of the C2 carbon atom of the sn-1 lipid tail, meaning that the bilayer conserves its integrity. Since total internalization of CX-1 was not observed in the unconstrained MD time-scale, constant velocity steered molecular dynamics (SMD) simulations were performed in order to simulate the CX-1 permeation across the bilayer. At pulling velocities lower than 0.0075 nmps(-1), chloride transport was observed. The Potential of Mean Force (PMF), calculated with the weighted histogram analysis method, indicates a barrier of ca. 58kJmol(-1) for this mobile carrier to cross the membrane., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Three triazolium-based [2]rotaxanes containing different sized axle and macrocycle components were synthesised in good yields (40-57%) through chloride anion templation. The anion recognition properties of the interlocked receptor systems were investigated using (1)H NMR titration experiments: all three rotaxanes display impressive selectivities for halide anions over the more basic oxoanion acetate. The rotaxanes incorporating shorter, more rigid axle components with aryl-substituted triazolium groups display substantially higher anion binding affinities than those with longer, bis-alkyl-substituted heterocycles, which is attributed to the increased intercomponent preorganisation afforded by the smaller axle component. Computational DFT and molecular dynamics simulations composed of unconstrained and umbrella sampling simulations corroborate the experimental observations., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Small non-coding regulatory RNAs (sRNAs) play important roles in regulating gene expression at the post-transcriptional level and often require the RNA chaperone Hfq. The human opportunistic pathogen Burkholderia cenocepacia J2315 encodes two distinct RNA chaperones, Hfq and Hfq2. The present work describes the experimental identification and validation of 24 sRNAs from B. cenocepacia J2315, based on the co-purification of sRNAs with the bacterium Hfq protein, followed by conversion into cDNA, cloning, computational analysis of sequences and validation by Northern blot analysis. The sRNAs here reported escaped identification by previous studies based on transcriptomics or bioinformatic analyses. Results presented indicate that 3 sRNAs are exclusive to bacteria of the Burkholderia cepacia complex and have no homologues in other bacteria, while the other 21 share homology, at different extents, to sRNAs of other bacterial species., (Copyright © 2012 Elsevier Inc. All rights reserved.)