Plant peptidoglycan precursor biosynthesis: Conservation between moss chloroplasts and Gram negative bacteria

An accumulation of evidence suggests that peptidoglycan, consistent with a bacterial cell wall, is synthesised around the chloroplasts of many photosynthetic eukaryotes, from glaucophyte algae to land plants at least as evolved as pteridophyte ferns, but the biosynthetic pathway has not been demonstrated. We employed mass spectrometry and enzymology in a two fold approach to characterize the synthesis of peptidoglycan in chloroplasts of the moss Physcomitrium (Physcomitrella) patens. To drive the accumulation of peptidoglycan pathway intermediates, P.patens was cultured with the antibiotics phosphomycin, D-cycloserine and carbenicillin, which inhibit key peptidoglycan pathway proteins in bacteria. Mass spectrometry of the TCA-extracted moss metabolome revealed elevated levels of five of the predicted intermediates from UDP-GlcNAc through to the UDP-MurNAc-D,L-diaminopimelate (DAP)-pentapeptide. Most Gram negative bacteria, including cyanobacteria, incorporate meso-diaminopimelate (D,L-DAP) into the third residue of the stem peptide of peptidoglycan, as opposed to L-Lysine, typical of most Gram positive bacteria. To establish the specificity of D,L-DAP incorporation into the P.patens precursors, we analysed the recombinant protein that appends the third stem peptide amino acid, UDP-MurNAc-tripeptide ligase (MurE), from both P.patens and the cyanobacterium Anabaena sp. strain PCC 7120. Both ligases incorporated D,L-DAP in almost complete preference to L-Lys, consistent with the mass spectrophotometric data, with catalytic efficiencies similar to previously documented Gram negative bacterial MurE ligases. We discuss how these data accord with the conservation of active site residues common to DL-DAP-incorporating bacterial MurE ligases and of the probability of a horizontal gene transfer event within the plant peptidoglycan pathway.

Multivariate Model Update Chemometric Methods for Determination of Prednisolone and Esomeprazole in Spiked Human Plasma: a Comparative Study

Background Prednisolone is immunosuppressant and anti-inflammatory drug; it may cause peptic ulcers as a side effect. Esomeprazole is used for treatment of peptic ulcers therefore; the two drugs are co-administered in case of organ transplantation and autoimmune diseases. Objective This work aims to determine simultaneously the two drugs together in bulk and spiked human plasma by eliminating the overlapping between the spectra of each other and the interference of plasma matrix. Methods Two simple and effective model updated chemometric models called principal component analysis (PCA) and partial least square (PLS) were established using UV spectrophotometric data. Results The two updated models have been validated according to the U.S. Food and Drug Administration guidelines with accepted results. The results were statistically compared with those of the reported methods, where no significant difference was found, indicating the validity of the developed methods. The two updated models have been successfully applied for prediction of the proposed drugs with good results regarding accuracy and precision. Conclusion The two updated models are simple, rapid, sensitive, and precise and could be easily applied in quality control laboratories for determination of PRD and ESO, without any preliminary separation steps or interference from plasma matrix. Highlights Two model updated chemometric models called PCA and PLS were established for determination of prednisolone and esomeprazole in spiked human plasma using UV spectrophotometric data.

CHARACTERISATION OF COAT COLOUR IN THE SLOVENIAN POSAVJE HORSE

Different approaches and classification systems have been established to describe equine coat colour, which varies between breeds and countries. In the present study, we first characterised the coat colour variability in the Slovenian Posavje Horse applying colour spectrophotometry following the CIE L*a*b system. As derived from the classification system of Sponenberg (light bay, bay, mahogany bay, brown and seal brown), the phenotype categories could be confirmed by spectrophotometric data. Furthermore, L*a*b values revealed comparable high phenotypic variability of bay coat colour in the Posavje breed, and the darker shades of bay coat colour were associated with the ASIP and MC1R genotype combination A/a E/E. CIE L*a*b colour spectrophotometry represents an effective tool to characterise and quantify coat colour in horses, especially in chestnut horses, for which the underlying genetic background of coat colour variation remains unknown.Key words: Posavje Horse; MC1R; ASIP; coat colour; spectrophotometry; CIE L*a*b KARAKTERIZACIJA BARVE DLAKE PRI POSAVSKEM KONJU Izvleček: Za opis barv konj se uporabljajo različni pristopi in klasifikacijski sistemi, ki se razlikujejo med posameznimi pasmami in državami. V raziskavi smo najprej opredelili različne barve dlake pri posavskem konju z metodo barvne spektrofotometrije po sistemu CIE L*a*b*. Fenotipsko razdelitev barv dlake po Sponenbergu (light bay/svetli rjavec, bay/rjavec, mahogany bay/kostanjev, brown/temni rjavec and seal brown/črnkast rjavec) smo potrdili s spektrofotometričnimi podatki. Vrednosti L*a*b so pri posavskem konju pokazale primerljivo visoko fenotipsko variabilnost rjave barve, pri tem so bili temnejši odtenki povezani z ASIP in MC1R kombinacijo genotipa A/a E/E. Barvna spektrofotometrija po sistemu CIE L*a*b predstavlja učinkovito orodje za kvalitativno in kvantitativno opredelitev/določanje barv pri konjih, zlasti pri lisjakih, pri katerih še vedno ni znana genska osnova variabilnosti v barvi dlake.Ključne besede: posavski konj; MC1R; ASIP; barva dlake; spektrofotometrija; CIE L*a*b

Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

Colorimetric Chemosensor Array for Determination of Halides

The halide anions are essential for supporting life. Therefore, halide anion analyses are of paramount importance. For this reason, we have performed both qualitative and quantitative ana- lyses of halides (chloride, bromide, iodide) using the Tl(III) complex of azodye, 4-(2-pyridylazo)re- sorcinol (PAR), a potential new chemical reagent/sensor that utilizes the substitution reaction whereas the Tl(III)PAR complex reacts with a halide to yield a more stable thallium(III)-halide while releasing the PAR ligand in a process accompanied by color change of the solution. The experimental conditions (e.g., pH, ratio metal ion-to-ligand ratio, etc.) for the substitution reaction between the metal complex and a halide were optimized to achieve increased sensitivity and a lower limit of detection (chloride 7 mM, bromide 0.15 mM, iodide 0.05 mM). It is demonstrated that this single chemosensor can, due to release of colored PAR ligand and the associated analyte-specific changes in the UV/VIS spectra, be employed for a multicomponent analysis of mixtures of anions (chloride + bromide, chloride + iodide, bromide + iodide). The spectrophotometric data evaluated by artificial neural networks (ANNs) enable distinguishing among the halides and to determine halide species concentrations in a mixture. The Tl(III)-PAR complex was also used to construct sensor arrays utilizing a standard 96-well plate format where the output was recorded at several wavelengths (up to 7) using a conventional plate reader. It is shown that the data obtained using a digital scanner employing only three different input channels may also be successfully used for a subsequent ANN analysis. The results of all approaches utilized for data evaluation were similar. To increase the practical utility of the chemosensor, we have developed a test paper strip indicator useful for routine naked-eye visual determination of halides. This test can also be used for halide anion determination in solutions using densitometer. The methodology described in this paper can be used for a simple, inexpensive, and fast routine analysis both in a laboratory as well as in a field setting.

Controlling the adsorption of mineral porous particles by chelation

Problem formulating. To increase the sorption capacity of calcium carbonate microparticles used as core for the development of targeted drug delivery, EDTA chelation of calcium ions was used to form a developed active surface of the particles. Goal. Is in modification of the surface of micron and submicron calcium carbonate vaterite particles using EDTA chelation of calcium ions and studying the effect of particle processing on their sorption capacity. Result. It was shown using scanning electron microscopy that EDTA treatment of the CaCO3 surface leads to an increase on the surface roughness of the particles, as well as an increase on their sorption capacity according to spectrophotometric data. Practical meaning. Use of adsorption to encapsulate the active substance inside the carriers. It is shown that an increase in the sorption capacity of particles leads to an increase in the amount of a substance inside its volume.

Identification of pigments in artworks by inverse tangent derivative of spectrum and a new filtering method

Employing an economical and non-destructive method for identifying pigments utilized in artworks is a significant aspect for preserving their antiquity value. One of the non-destructive methods for this purpose is spectrophotometry, which is based on the selected absorption of light. Mathematical descriptive methods such as derivatives of the reflectance spectrum, the Kubelka–Munk function and logarithm have been employed for the characterization of the peak features corresponding to the spectrophotometric data. In the present study, the mentioned mathematical descriptive methods were investigated with the aim to characterize the constituents of an Iranian artwork but were not efficient for the samples. Therefore, inverse tangent derivative equation was developed on spectral data for the first time, providing considerable details in the profile of reflectance curves. In the next part, to have a simpler and more practical method it was suggested to use filters made up of pure pigments. By using these filters and placing them on the samples, imaging was done. Then, images of samples with and without filter were evaluated and pure pigments were distinguished. The mentioned methods were also used to identify pigments in a modern Iranian painting specimen. The results confirmed these methods with reliable answers indicating that physical methods (alongside chemical methods) can also be effective in determining the types of pigments.

Identification of pigments in artworks by inverse tangent derivative of spectrum and a new filtering method

Employing an economical and non-destructive method for identifying pigments utilized in artworks is a significant aspect for preserving their antiquity value. One of the non-destructive methods for this purpose is spectrophotometry, which is based on the selected absorption of light. Mathematical descriptive methods such as derivatives of the reflectance spectrum, the Kubelka-­Munk function and logarithm have been employed for the characterization of the peak features corresponding to the spectrophotometric data. In the present study, the mentioned mathematical descriptive methods were investigated with the aim to characterize the constituents of an Iranian artwork but were not efficient for the samples. Therefore, inverse tangent derivative equation was developed on spectral data for the first time, providing considerable details in the profile of reflectance curves. In the next part, to have a simpler and more practical method it was suggested to use filters made up of pure pigments. By using these filters and placing them on the samples, imaging was done. Then, images of samples with and without filter were evaluated and pure pigments were distinguished. The mentioned methods were also used to identify pigments in a modern Iranian painting specimen. The results confirmed these methods with reliable answers indicating that physical methods (alongside chemical methods) can also be effective in determining the types of pigments.

Application of Rank Annihilation Factor Analysis for Antibacterial Drugs Determination by Means of pH Gradual Change-UV Spectral Data

The main objective of this study was to develop a simple and efficient spectrophotometric technique combined with chemometrics for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) in drug formulations. Specifically, we sought: (i) to evaluate the potential use of rank annihilation factor analysis (RAFA) to pH gradual change spectrophotometric data in order to provide sufficient accuracy and model robustness; and (ii) to determine SMX and TMP concentration in drug formulations without tedious pre-treatments such as derivatization or extraction techniques which are time-consuming and require hazardous solvents. In the proposed method, the spectra of the sample solutions at different pH values were recorded and the pH-spectra bilinear data matrix was generated. On these data, RAFA was then applied to estimate the concentrations of SMX and TMP in synthetic and real samples. Applying RAFA showed that the two drugs could be determined simultaneously with concentration ratios of SMX to TMP varying from 1:30 to 30:1 in the mixed samples (concentration range is 1–30 µg mL−1 for both components). The limits of detection were 0.25 and 0.38 µg mL−1 for SMX and TMP, respectively. The proposed method was successfully applied to the simultaneous determination of SMX and TMP in some synthetic, pharmaceutical formulation and biological fluid samples. In addition, the means of the estimated RSD (%) were 1.71 and 2.18 for SMX and TMP, respectively, in synthetic mixtures. The accuracy of the proposed method was confirmed by spiked recovery test on biological samples with satisfactory results (90.50–109.80%).