Remdesivir as a broad-spectrum antiviral drug against COVID-19.

OBJECTIVE: List the clinical data of the role of remdesivir in COVID-19, and try to make an objective evaluation and analyze its feasibility. MATERIALS AND METHODS: The keywords of "remdesivir", "COVID-19" and "SARS-CoV-2" were systematically searched in PubMed and Web of Science. After removing the repetitions, we summarize articles, letters, and comments on remdesivir in the treatment of COVID-19. RESULTS: In this review, we summarize clinical case of using remdesivir in the treatment of COVID-19, analyzed the final treatment results, and judged whether the drug was effective for the treatment of COVID-19. Also, attention was paid to the side effects of the drug. CONCLUSIONS: According to the clinical results, it was found that remdesivir was effective in the treatment of COVID-19. The drug has side effects, but the symptoms were mild and disappeared immediately after discontinuation of medication.

Polysaccharides and phytochemicals: a natural reservoir for the green synthesis of gold and silver nanoparticles.

Currently, sustainability initiatives that use green chemistry to improve and/or protect our global environment are becoming focal issues in many fields of research. Instead of using toxic chemicals for the reduction and stabilisation of metallic nanoparticles, the use of various biological entities has received considerable attention in the field of nanobiotechnology. Among the many possible natural products, polysaccharides and biologically active plant products represent excellent scaffolds for this purpose. Polysaccharides have hydroxyl groups, a hemiacetal reducing end, and other functionalities that can play important roles in both the reduction and the stabilisation of metallic nanoparticles. Among the various categories of compounds in plants that have potent biological activities, phytochemicals are emerging as an important natural resource for the synthesis of metallic nanoparticles. The focus of this review is the application of polysaccharides and phytochemicals in the green synthesis of gold and silver nanoparticles to afford biocomposites with novel uses in nanomedicine and as nanocomposites.

Constitutive expression of rice MADS box gene using seed explants in hot pepper (Capsicum annuum L.).

Two transgenic pepper plants were obtained from 255 seed explants that were infected with Agrobacterium LBA4404 (pGA1209). One of them (PT2) showed morphological change, such as dwarfism and early flowering by the constitutive expression of the rice OsMADS1 gene. The in vitro condition of the plant regeneration has been optimized from hypocotyl explants on a MS medium that was supplemented with zeatin 3 mg/L, IAA 0.3 mg/L for shoot induction. The optimal rooting condition was at NAA 0.3 mg/L. The transformation frequency was 0.8% from the total hypocotyls. DNA and RNA hybridization analyses showed that the introduced gene was integrated and stably expressed in regenerated plants.

Photoinactivation of photosystem II complexes and photoprotection by non-functional neighbours in Capsicum annuum L. leaves.

Leaf segments from Capsicum annuum plants grown at 100 micromol photons m(-2) s(-1) (low light) or 500 micromol photons m(-2) s(-1) (high light) were illuminated at three irradiances and three temperatures for several hours. At various times, the remaining fraction (f) of functional photosystem II (PS II) complexes was measured by a chlorophyll fluorescence parameter (1/Fo -1/Fm, where Fo and Fm are the fluorescence yields corresponding to open and closed PS II traps, respectively), which was in turn calibrated by the oxygen yield per saturating single-turnover flash. During illumination of leaf segments in the presence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis, the decline of f from 1.0 to about 0.3 was mono-exponential. Thereafter, f declined much more slowly, the remaining fraction (approximately equals 0.2) being able to survive prolonged illumination. The results can be interpreted as being in support of the hypothesis that photoinactivated PS II complexes photoprotect functional neighbours (G. Oquist et al. 1992, Planta 186: 450-460), provided it is assumed that a photoinactivated PS II is initially only a weak quencher of excitation energy, but becomes a much stronger quencher during prolonged illumination when a substantial fraction of PS II complexes has also been photoinactivated. In the absence of lincomycin, photoinactivation and repair of PS II occur in parallel, allowing f to reach a steady-state value that is determined by the treatment irradiance, temperature and growth irradiance. The results obtained in the presence and absence of lincomycin are analysed according to a simple kinetic model which formally incorporates a conversion from weak to strong quenchers, yielding the rate coefficients of photoinactivation and of repair for various conditions, as well as gaining an insight into the influence off on the rate coefficient of photoinactivation. They demonstrate that the method is a convenient alternative to the use of radiolabelled amino acids for quantifying photoinactivation and repair of PS II in leaves.

Regulation of nitrite reductase by light and nitrate in the cotyledons of hot pepper (Capsicum annuum L.).

Light and nitrate are the major factors regulating the nitrite reductase (NiR) amongst various environmental and metabolic cues in plants. Hot pepper was used to investigate this regulatory mechanism of the NiR gene expression and its dependency on light and nitrate. The major results from this study are: (I) the nir partial clone (581 bp) obtained from hot pepper genomic DNA by degenerative polymerase chain reaction exhibited an amino acid sequence that is highly homologous with other plants. (II) Genomic DNA blot analysis and the NiR electrophoretic assay revealed that a small multigene family encodes NiR, which exists at least in two isoforms. (III) The light-mediated increase of NiR activity is correlated with the nitrate concentration, showing saturation kinetics above 50 mM of nitrate. (IV) Exogenous nitrate was required for the appearance of nir transcripts, but not for the enzyme activity. These results suggest that the gene expression of NiR in hot pepper is determined by the presence of nitrate at the transcriptional level. Furthermore, light has a synergistic effect on the action of nitrate on NiR levels.

Acid- and Enzyme-Mediated Solubilization of Cell-Wall beta-1.3,beta-1.4-d-Glucan in Maize Coleoptiles : Implications for Auxin-Mediated Growth.

The release of soluble carbohydrates from isolated cell wall of maize (Zea mays L.) was investigated in the range of pH 1 to 8.5. The pH profile demonstrated two peaks, a broad peak at pH 6 due to enzymatic breakdown of beta-glucan to monosaccharides (wall autolysis) and a sharp peak at pH 2.5 due to acid-mediated, nonenzymatic liberation of macromolecular beta-glucan from the wall. The pH dependence of acid-induced growth and cell-wall extensibility of coleoptile segments closely agrees with the pH dependence of acid-mediated beta-glucan solubilization in the isolated wall. However, there is no evidence that enzymatic or nonenzymatic beta-glucan solubilization is involved in the mechanism of auxin-mediated growth.

Control by phytochrome of urate oxidase and allantoinase activities during peroxisome development in the cotyledons of mustard (Sinapis alba L.) seedlings.

The peroxisomal enzyme, urate oxidase (EC 1.7.3.3), and the next enzyme of the urate pathway, allantoinase (EC 3.5.2.5), demonstrate a lightmediated rise of activity in the cotyledons of mustard (Sinapis alba L.). The capacity of the peroxisomes for urate breakdown, marked by the time course of urate oxidase, develops distinctly later than the two other peroxisome functions (fatty acid breakdown, "glyoxysomal" function; glycolate breakdown, "leaf peroxisomal" function). The light effect on urate oxidase and allantoinase is mediated through the phytochrome system in all three seedling organs (cotyledons, hypocotyl, radicle), as revealed by induction/reversion experiments with red/far-red light pulses and continuous irradiation with far-red light (high irradiance reaction of phytochrome). Both enzyme activities can be induced by phytochrome in the seedling cotyledons only during a sensitive period of about 48 h prior to the actual light-mediated rise of activity, making it necessary to assume the existence of a long-lived intermediate ("transmitter") in the signal response chain connecting enzyme formation to the phytochrome system. Detailed kinetic investigation, designed to test whether urate oxidase and allantoinase are controlled by phytochrome via the same signal response chain (coordinate induction), revealed large differences between the two enzymes: (i) a different onset of the loss of reversibility of a red light induction by a far-red light pulse (=onset of transmitter formation=coupling point; 48 h/24 h after sowing for urate oxidase/allantoinase); (ii) a different onset of the response (=onset of competence for transmitter= starting point; 72 h/48 h); (iii) full loss of reversibility (=completion of transmitter formation) is reached at different times (independence point, 90 h/52 h). These differences show that phytochrome controls urate oxidase and allantoinase via separate signal response chains. While urate oxidase can be localized in the peroxisomal fraction isolated from crude organelle extracts of the cotyledons by density gradient centrifugation, most of the allantoinase activity found in the peroxisomal fraction did not appear to be an integral part of the peroxisome but originated presumably from adhering membrane fragments.

Density of Microbodies on Sucrose Gradients during Phytochrome-mediated Glyoxysome Peroxisome Transformation in Cotyledons of Mustard Seedlings.

The microbodies extracted from the cotyledons of mustard seedlings (Sinapis alba L.) form two bands (at 1.18 kilograms per liter together with the mitochondria, and at 1.24 kilograms per liter) on conventional isopycnic sedimentation density gradients. The artifactual co-banding of part of the microbodies with the mitochondria can be prevented by using flotation gradients. Using this procedure, a systematic investigation revealed no effect of seedling age and irradiation (far red or white light) on the density of the microbody population (1.242 +/- 0.002 kilograms per liter). Thus, although light, through phytochrome, induces conspicuous changes in their enzyme composition the microbodies appear as a homogeneous population of constant density on a sucrose gradient.

Formation of oleosomes (storage lipid bodies) during embryogenesis and their breakdown during seedling development in cotyledons of Sinapis alba L.

Electron microscopic and biochemical investigations of developing embryonic mustard cotyledons provided no evidence for the widely accepted hypothesis that oleosomes of fat-storing tissues originate from the endoplasmic reticulum and are surrounded by a unit- or half-unit membrane. In contrast, it was found that the first lipid droplets appear (about 12-14 d after pollination) in the ground cytoplasm near the surface of plastids. Subsequently these nascent lipid droplets, which lack any detectable boundary structure at this stage, become encircled by a cisterna of rough endoplasmic reticulum. At the same time an osmiophilic coat of about 3 nm thickness becomes detectable at the lipid/water interface. In the cotyledon cells of germinating seedlings a centrifugally moving front of fat degradation moves from the central vacuoles(s) towards the cell periphery, leaving behind collapsed coats of oleosomes which are depleted of their lipid contents (saccules). Although saccules appear tripartite in cross section, they are structurally different from endoplasmic reticulum membranes. The oleosome coats can be isolated from oleosome preparations by extracting lipids with organic solvents. The coat material is insoluble in detergents like Triton X-100 or deoxycholate and shows a tripartite, lamellar structure (similar to collapsed saccules) under the electron microscope. Upon dissolution with dodecylsulfate, polyacrylamide gel electrophoresis revealed a polypeptide composition (9 major bands) which is qualitatively different from that of the endoplasmic reticulum membrane. Also the buoyant densities of defatted oleosome coats and defatted endoplasmic reticulum membranes are very different. It is concluded that oleosome lipids accumulate in the ground cytoplasm and are bounded by a lamellar structure originating de novo from proteinaceous elements synthesized by specific regions of the endoplasmic reticulum.