Toll-Like Receptor 22 in Labeo rohita: Molecular Cloning,Characterization, 3D Modeling,and Expression Analysis Following Ligands Stimulation and Bacterial Infection

Toll-like receptors (TLRs) are a class of innate immune receptors that sense pathogens or their molecular signatures and activate signaling cascades to induce a quick and non-specific immune response in the host. Among various types of TLRs, TLR22 is exclusively present in teleosts and amphibians and is expected to play the distinctive role in innate immunity. This report describes molecular cloning, three-dimensional (3D) modeling, and expression analysis of TLR22 in rohu (Labeo rohita), the most commercially important freshwater fish species in the Indian subcontinent. The open reading frame (ORF) of rohu TLR22 (LrTLR22) comprised of 2,838 nucleotides (nt), encoding 946 amino acid (aa) residues with the molecular mass of ～107.6 kDa. The secondary structure of deduced LrTLR22 exhibited the presence of signal peptide (1–22 aa), 18 leucine-rich repeat (LRR) regions (79–736 aa), and TIR domain (792–935 aa). The 3D model of LrTLR22-LRR regions together elucidated the horse-shoe-shaped structure having parallel β-strands at the concave surface and few α-helices at the convex surface. The TIR domain structure revealed alternate presence of five α-helices and β-sheets. Phylogenetically, LrTLR22 was closely related to common carp and exhibited significant similarity (92.2 %) and identity (86.1 %) in their amino acids. In rohu, TLR22 was constitutively expressed in all embryonic developmental stages, and tissue-specific analysis illustrated its expression in all examined tissues, highest was in liver and lowest in brain. In vivo modulation of TLR22 gene expression was analyzed by quantitative real-time PCR (qRT-PCR) assay following stimulation with lipopolysaccharide (LPS), synthetic double stranded RNA (polyinosinic-polycytidylic acid), and bacterial (Aeromonas hydrophila) RNA. Among these ligands, bacterial RNA most significantly (p?A. hydrophila infection, induction of TLR22 gene expression was also observed in majority of the tested tissues. Together, these data suggested that in addition to sensing other microbial signatures, TLR22 can recognize bacterial RNA and may play the important role in augmenting innate immunity in fish.     

A comparative metal ion adsorption study by trimesic acid coated alumina: a potent adsorbent

Benzene-1,3,5-tri-carboxylic acid (trimesic acid, TMA) coated on basic alumina has been shown to be an effective adsorbent for Fe(III) and Fe(II) from aqueous solution. A comparative study on the adsorption of Fe(III) and Fe(II) revealed that TMA coated alumina is more selective towards Fe(III) than Fe(II). The maximum adsorptions of Fe(III) and Fe(II) were 26.6 mg/g and 8.4 mg/g, respectively. Fe(III)/Fe(II) adsorption was also compared in some cases with adsorption of Co(II) and Ni(II). Maximum uptakes (Qm) for Co(II) and Ni(II) were found much lower (approximately 1 mg/g) than Fe(III)/Fe(II). pH dependent studies have revealed that Fe(III) was adsorbed efficiently at high acidic condition (pH approximately 1.5) compared to Fe(II), Co(II) and Ni(II), while temperature did not have significant effect on the adsorption processes. Adsorption of Fe(III) and Fe(II) was quite rapid and thermodynamically favourable. Adsorption processes fitted well in Langmuir isotherm model and followed second order rate kinetics in all cases.     

Regioselective Synthesis of Quinazolinone‐/Phenanthridine‐Fused Heteropolycycles by Pd‐Catalyzed Direct Intramolecular Aerobic Oxidative C−H Amination from Aromatic Strained Amides

A new route for the expedient synthesis of specific regioisomer of quinazolinone‐ and phenanthridine‐fused heterocycles through a palladium‐catalyzed regioselective intramolecular oxidative C?H amination from cyclic strained amides of aromatic amido–amidine systems (quinazolinones) has been developed. The amine functionalization of an aromatic C?H bond from a strained amide nitrogen involved in aromaticity has been a challenging work so far. The fusion of two heterocyclic cores, quinazolinone and phenanthridine, can occur in two different ways (linear and angular), but under the conditions reported here, only linear type isomer is exclusively produced. This approach provides a variety of substituted quinazolinone‐ and phenanthridine‐fused derivatives in moderate to excellent yields. Moreover, such fused molecules show excellent fluorescent properties and have great potential to be a new type of fluorophores for the use in medicinal and material science.     

An Efficient Fluorescence “Turn-On” Chemosensor Comprising of Coumarin and Rhodamine Moieties for Al<Superscript>3+</Superscript> and Hg<Superscript>2+</Superscript>

A potent fluorescence ‘turn-on’ receptor (HL) based on rhodamine and coumarin moieties for the detection of Hg²⁺ and Al³⁺ is synthesized by condensation of rhodamine 6G hydrazide and 4-hydroxy-3-acetylcoumarin. In presence of Al³⁺ and/or Hg²⁺ the receptor (HL) exhibits deep pink colouration and a sharp band at 528 nm is appeared in UV–vis titration. Upon gradual addition of Al³⁺ and/or Hg²⁺ to the solution of HL significant enhancement of fluorescence intensity is observed at 564 nm in MeCN:H₂O (1:5, v/v) medium. The receptor is strongly bound to Al³⁺ and/or Hg²⁺ and the association constants (K_a) are found to be 1.74?×?10⁴ and 1.04?×?10⁴ M^??1 for Al³⁺ and Hg²⁺ respectively.

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Graphical Abstract A potent fluorescence ‘turn-on’ receptor (HL) based on rhodamine and coumarin moieties for the detection of Hg²⁺ and Al³⁺ is synthesized and characterized. In presence of Al³⁺ and/or Hg²⁺ the receptor (HL) exhibits deep pink colouration and significant enhancement of fluorescence intensity is observed at 564 nm in MeCN:H₂O (1:5, v/v) medium. The receptor is strongly bound to Al³⁺ and/or Hg²⁺ and the association constants (K_a) are found to be 1.74?×?10⁴ and 1.04?×?10⁴ M^??1 for Al³⁺ and Hg²⁺ respectively.

     

Importance of steric factors in face-selective cycloadditions: 1,6-annulated cyclohexa-1,3-dienes

Diastereotopically nonequivalent π-facial 1,6-annulated-1,3-cyclohexadienes have been explored as probe molecules to assess the face-selectivities in cycloadditions. Steric factors have been found to be important in controlling the face-selectivities with these dienes. Studies with the hitherto unexplored diene 5 were also consistent with the order C-H > C-C for hyperconjugative stabilization of the transition state.     

Face-selective Diels-Alder reactions between unsymmetrical cyclohexadienes and symmetric trans-dienophile: an experimental and computational investigation

A combined experimental and theoretical study of the Diels-Alder reactions between 2-trimethylsiloxy-1,3-cyclohexadienes (2-11) and (E)-1,4-diphenylbut-2-ene-1,4-dione (1) is reported. Two diastereomeric products, 5-endo-6-exo- (nx) and 5-exo-6-endo- (xn) dibenzoyl derivatives, are possible with symmetric trans-dienophile (1). While in many cases 5-endo-6-exo product is preferred over the corresponding 5-exo-6-endo product, the product ratio nx:xn is found to vary with the position of substituents on the diene. The density functional theory studies with the mPW1PW91/6-31G* as well as the B3LYP/6-31G* levels reveal that the electrostatic repulsion between the oxygen lone pairs on the diene and the dienophile is critical to the observed product selectivities. The optimized transition state geometries though appeared to involve secondary orbital interactions, careful examination of the frontier Kohn-Sham orbitals as well as calculations with the natural bond orbital (NBO) analyses confirm the absence of SOI in these transition states. In the case of methyl-substituted dienes, a cumulative effect of steric and electrostatic interactions between the diene and the dienophile is found to be the controlling element toward the observed selectivity.     

Hydroxamic acid dinuclear complexes of molybdenum(V) and molybdenum(III)

Summary Molybdenum(V) and molybdenum(III) complexes [Mo₂O₃L₄] and [Mo₂L₆] derived from hydroxamic acids (HL) were prepared and identified by Raman, i.r., e.s.r., electronic spectra and analytical data. The low magnetic moments of the dinuclear complexes are due to in part to intramolecular interactions. Electronic spectra and vibrational studies indicate the presence of a Mo₂O₃ core in the molybdenum(V) complexes. The relative intensities of the, main and satellite peaks in e.s.r. spectra indicate the dinulcear nature of molybdenum(III) hydroxamates.