Research on the drought tolerance mechanism of Pennisetum glaucum (L.) in the root during the seedling stage.

BACKGROUND: Drought is one of the major environmental stresses resulting in a huge reduction in crop growth and biomass production. Pearl millet (Pennisetum glaucum L.) has excellent drought tolerance, and it could be used as a model plant to study drought resistance. The root is a very crucial part of plant that plays important roles in plant growth and development, which makes it a focus of research. RESULTS: In this study, we explored the mechanism of drought tolerance of pearl millet by comparing physiological and transcriptomic data under normal condition and drought treatment at three time points (1 h, 3 h and 7 h) in the root during the seedling stage. The relative electrical conductivity went up from 1 h to 7 h in both control and drought treatment groups while the content of malondialdehyde decreased. A total of 2004, 1538 and 605 differentially expressed genes were found at 1 h, 3 h and 7 h respectively and 12 genes showed up-regulation at all time points. Some of these differentially expressed genes were significantly enriched into 'metabolic processes', 'MAPK signaling pathway' and 'plant hormone signal transduction' such as the ABA signal transduction pathway in GO and KEGG enrichment analysis. CONCLUSIONS: Pearl millet was found to have a quick drought response, which may occur before 1 h that contributes to its tolerance against drought stress. These results can provide a theoretical basis to enhance the drought resistance in other plant species.

Pharmacokinetics and relative bioavailability of meloxicam oil suspension in pigs after intramuscular administration.

This study aimed to develop one novel meloxicam (MEL) oil suspension for sustained-release and compare the pharmacokinetic characteristics of it with MEL conventional formulation in pigs after a single intramuscular administration. Six healthy pigs were used for the study by a crossover design in two periods with a withdrawal interval of 14 days. Plasma concentrations of MEL were measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetic parameters were calculated by noncompartmental methods. The difference was statistically significant (p < .05) between MEL oil suspension and MEL conventional formulation in pharmacokinetic parameters of mean residence time (6.16 ± 4.04) hr versus (2.66 ± 0.55) hr, peak plasma concentration (Cmax ) (0.82 ± 0.12) µg/ml versus (1.12 ± 0.22) µg/ml, time needed to reach Cmax (Tmax ) (2.33 ± 0.82) hr versus (0.59 ± 0.18) hr, and terminal elimination half-life (t1/2λz ) (3.74 ± 2.66) hr versus (1.55 ± 0.37) hr. The mean area under the concentration-time curve (AUC0-∝ ) of MEL oil suspension and MEL conventional formulation was 5.35 and 3.43 hr µg/ml, respectively, with a relative bioavailability of 155.98%. Results of the present study demonstrated that the MEL oil suspension could prolong the effective time of drugs in blood, thereby reducing the frequency of administration on a course of treatment. Therefore, the novel MEL oil suspension seems to be of great value in veterinary clinical application.

The whole-genome and expression profile analysis of WRKY and RGAs in Dactylis glomerata showed that DG6C02319.1 and DgWRKYs may cooperate in the immunity against rust.

Orchardgrass (Dactylis glomerata) is one of the top four perennial forages worldwide and, despite its large economic advantages, often threatened by various environmental stresses. WRKY transcription factors (TFs) can regulate a variety of plant processes, widely participate in plant responses to biotic and abiotic stresses, and are one of the largest gene families in plants. WRKYs can usually bind W-box elements specifically. In this study, we identified a total of 93 DgWRKY genes and 281 RGAs, including 65, 169 and 47 nucleotide-binding site-leucine-rich repeats (NBS-LRRs), leucine-rich repeats receptor-like protein kinases (LRR-RLKs), and leucine-rich repeats receptor-like proteins (LRR-RLPs), respectively. Through analyzing the expression of DgWRKY genes in orchardgrass under different environmental stresses, it was found that many DgWRKY genes were differentially expressed under heat, drought, submergence, and rust stress. In particular, it was found that the greatest number of genes were differentially expressed under rust infection. Consistently, GO and KEGG enrichment analysis of all genes showed that 78 DgWRKY TFs were identified in the plant-pathogen interaction pathway, with 59 of them differentially expressed. Through cis-acting element prediction, 154 RGAs were found to contain W-box elements. Among them, DG6C02319.1 (a member of the LRR-RLK family) was identified as likely to interact with 14 DGWRKYs. Moreover, their expression levels in susceptible plants after rust inoculation were first up-regulated and then down-regulated, while those in the resistant plants were always up-regulated. In general, DgWRKYs responded to both biotic stress and abiotic stress. DgWRKYs and RGAs may synergistically respond to the response of orchardgrass to rust. This study provides meaningful insight into the molecular mechanisms of WRKY proteins in orchardgrass.

Comparative pharmacokinetics of meloxicam oil suspension in pigs at different dosages following intramuscular administration.

This study aimed to evaluate the preliminary safety of self-developed meloxicam (MEL) oil suspension and determine the comparative pharmacokinetics of it at 0.8 and 2mg/kg body weight (b.w.) dosages in pigs following a single intramuscular administration. Six rabbits were used for the study of preliminary safety and six healthy pigs were used for pharmacokinetics study by a crossover design in two periods. The muscle irritation results showed that both of the MEL oil suspension and the conventional injection had no significant changes at the dosage of 0.4 mg/kg b.w.. However, at the dosage of 2 mg/kg b.w., both of the self-developed MEL oil suspension and the MEL conventional injection showed mild irritation to muscle. Plasma concentrations of MEL were measured by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The MEL plasma concentrations were quantified up to 30 h and 72 h after intramuscular administration at the low- and high-dosage, respectively. The difference was statistically significant (P < 0.05) between different dosages in pharmacokinetic parameters of t1/2λz, Cmax, AUC0-t, AUC0-µ, MRT, and Vd. The Cmax values of MEL were 1.92 ± 0.34 µg/ml and 3.03 ± 1.25 µg/ml at dosages of 0.8 and 2 mg/kg b.w. while the tmax values were 3.25 ± 1.04 h and 4.00 ± 1.26 h, respectively. The pharmacokinetics results of self-developed MEL oil suspension demonstrated that the retention time of it in pigs was prolonged, showing the sustained-release effect. Therefore, Oil suspension was an ideal new drug loading form of MEL.

Transcriptome profiling of two Dactylis glomerata L. cultivars with different tolerance in response to submergence stress.

Submergence is one of the environmental stresses that limit plant growth and development. Dactylis glomerata L. is an important cool-season forage grass globally. To investigate the genes related to submergence response and the molecular mechanism associated with submergence tolerance, the transcriptome of D. glomerata in response to waterlogging treatment was analyzed. RNA-sequencing was performed in two D. glomerata cultivars, submergence tolerant 'Dianbei' and submergence sensitive 'Anba'. A total of 50,045 unique genes matched the known proteins in the NCBI nr database by BLAST searches and 60.8% (30,418) of these genes were annotated with GO terms. Among these, 1395 genes only differentially expressed in 'Dianbei' and 18 genes shown different expression all the time were detected between the submergence tolerant 'Dianbei' and sensitive 'Anba'. Gene ontology (GO) and KEGG pathway enrichment analyses demonstrated that the DEGs were mainly implicated in oxidation-reduction system, nucleic acid binding transcription factor activity, and glycerol kinase activity. The D. glomerata assembled transcriptome provided substantial molecular resource for further genomic analysis of forage grasses in response to submergence stress. The significant difference in expression of specific unigenes may account for waterlogging tolerance or acclimation in the two different D. glomerata cultivars. This study provided new insights into the molecular basis of submergence tolerance in D. glomerata.