Abstract

In this work, it was found that the composition of hydroxyapatite coatings deposited on a titanium substrate depends on the temperature of detonation products and on the composition of the initial explosive mixture. Depending on the detonation mode, it was possible to obtain a coating of oxyhydroxyapatite containing or not containing an admixture of other calcium orthophosphates. It was shown for the first time that the structure of multisubstituted Zn–Si-hydroxyapatite and Ag–Zn–Si-hydroxyapatite with substitution degree x(Zn) = x(Si) = 0.2 and x(Ag) = 0.1 has lower thermal stability as compared to unsubstituted hydroxyapatite. The formation of a small amount of the α-Ca₃(PO₄)₂ phase upon detonation deposition of the multisubstituted hydroxyapatites was obviously due to structural transformations that occurred when the material was heated by the detonation products. In vivo biological testing of titanium implants coated or not coated with hydroxyapatite revealed that the coating significantly accelerates osteogenesis in the gap between native bone and the implant; this acceleration improved implant fixation. In animals with the uncoated plates, fibrogenesis processes significantly outstripped the osteogenesis. The presence of Zn and Si ions in the apatite coating had a potentiating influence on the osteoinduction caused by hydroxyapatite. Osteogenesis in this case was more complete and characterized by pronounced processes of mineralization of the bone plates. The addition of Ag ions to the Zn–Si-hydroxyapatite at a concentration of 1 at.% did not impair its osteogenic activity and did not have a toxic effect on bone tissue, while imparting antibacterial properties to the material.

 

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Simple Summary

The surface lipids of insects protect them from desiccation and may modulate susceptibility to fungal infections. We conducted a comparative analysis of cuticular lipids of the migratory locust and Italian locust. The former inhabits relatively wet landscapes and the latter more arid ones. We analyzed cuticular lipids of these species by gas chromatography with mass spectrometry and found that the Italian locust has a hydrocarbon profile shifted toward long chains as well as a higher content of di- and trimethyl branched hydrocarbons, which is most likely an adaptation to the arid climate and strong temperature fluctuations in its habitats. Meanwhile, the surface of the Italian locust proved to be more hospitable for fungi. The number of Metarhizium conidia attached to the Italian locust cuticle was three-fold greater as compared to the migratory locust. Mortality due to the fungal infection was faster in the Italian locust under laboratory conditions. We propose that species inhabiting arid landscapes rarely encounter fungal pathogens and primarily deal with the problem of desiccation. Therefore, they can afford a cuticle that is hospitable to fungal pathogens.

Abstract

Cuticular lipids protect insects from desiccation and may determine resistance to fungal pathogens. Nonetheless, the trade-off between these lipid functions is still poorly understood. The migratory locust Locusta migratoria and the Italian locust Calliptamus italicus have dissimilar hygrothermal preferences: L. migratoria inhabits areas near water bodies with a reed bed, and C. italicus exploits a wide range of habitats and prefers steppes and semideserts with the predominance of sagebrushes. This paper presents significant differences between these species’ nymphs in epicuticular lipid composition (according to gas chromatography with mass spectrometry) and in susceptibility to Metarhizium robertsii and Beauveria bassiana. The main differences in lipid composition are shifts to longer chain and branched hydrocarbons (di- and trimethylalkanes) in C. italicus compared to L. migratoria. C. italicus also has a slightly higher n-alkane content. Fatty acids showed low concentrations in the extracts, and L. migratoria has a wider range of fatty acids than C. italicus does. Susceptibility to M. robertsii and the number of conidia adhering to the cuticle proved to be significantly higher in C. italicus, although conidia germination percentages on epicuticular extracts did not differ between the species. We propose that the hydrocarbon composition of C. italicus may be an adaptation to a wide range of habitats including arid ones but may make the C. italicus cuticle more hospitable for fungi. View Full-Text

Keywords: alkanes; insect cuticle; climatic adaptations; mycoses; Metarhizium

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Abstract

Barley (Hordeum vulgare L.) grain pigmentation is caused by two types of phenolic compounds: anthocyanins (which are flavonoids) give a blue or purple color, and melanins (which are products of enzymatic oxidation and polymerization of phenolic compounds) give a black or brown color. Genes Ant1 and Ant2 determine the synthesis of purple anthocyanins in the grain pericarp, whereas melanins are formed under the control of the Blp1 gene in hulls and pericarp tissues. Unlike anthocyanin synthesis, melanin synthesis is poorly understood. The objective of the current work was to reveal features of the phenylpropanoid biosynthesis pathway functioning in melanin-accumulating barley grains. For this purpose, comparative transcriptomic and metabolomic analyses of three barley near-isogenic lines accumulating anthocyanins, melanins, or both in the grain, were performed. A comparative analysis of mRNA libraries constructed for three stages of spike development (booting, late milk, and early dough) showed transcriptional activation of genes encoding enzymes of the general phenylpropanoid pathway in all the lines regardless of pigmentation; however, as the spike matured, unique transcriptomic patterns associated with melanin and anthocyanin synthesis stood out. Secondary activation of transcription of the genes encoding enzymes of the general phenylpropanoid pathway together with genes of monolignol synthesis was revealed in the line accumulating only melanin. This pattern differs from the one observed in the anthocyanin-accumulating lines, where — together with the genes of general phenylpropanoid and monolignol synthesis pathways — flavonoid biosynthesis genes were found to be upregulated, with earlier activation of these genes in the line accumulating both types of pigments. These transcriptomic shifts may underlie the observed differences in concentrations of phenylpropanoid metabolites analyzed in the grain at a late developmental stage by high-performance liquid chromatography. Both melanin-accumulating lines showed an increased total level of benzoic acids. By contrast, anthocyanin-accumulating lines showed higher concentrations of flavonoids and p-coumaric and ferulic acids. A possible negative effect of melanogenesis on the total flavonoid content and a positive influence on the anthocyanin content were noted in the line accumulating both types of pigments. As a conclusion, redirection of metabolic fluxes in the phenylpropanoid biosynthesis pathway occurs when melanin is synthesized.

 

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