Characterization of transcription factor MYB59 and expression profiling in response to low K+ and NO3− in indica rice (Oryza sativa L.)

Background Nitrogen and potassium are crucial supplements for plant development and growth. Plants can detect potassium and nitrate ions in soils and in like way, they modify root-to-shoot transport of these ions to adjust the conveyance among roots and shoots. Transcription factor MYB59 plays essential roles in numerous physiological processes inclusive of hormone response, abiotic stress tolerance, plant development, and metabolic regulation. In this study, we retrieved 56 MYB59 proteins from different plant species. Multiple sequence alignment, phylogenetic tree, conserved motif, chromosomal localization, and cis-regulatory elements of the retrieved sequences were analyzed. Gene structure, protein 3D structure, and DNA binding of OsMYB59 indica were also predicted. Finally, we characterized OsMYB59 and its function under low K+/NO3− conditions in Oryza sativa subsp. indica. Results Data analysis showed that MYB59s from various groups separated in terms of conserved functional domains and gene structure, where members of genus Oryza clustered together. Plants showed reduced height and yellowish appearance when grown on K+ and NO3− deficient medium. Quantitative real-time PCR uncovered that the OsMYB59 reacted to abiotic stresses where its expression was increased in BRRI dhan56 but decreased in other varieties on K+ deficient medium. In addition, OsMYB59 transcript level increased on NO3− deficient medium. Conclusions Our results can help to explain the biological functions of indica rice MYB59 protein and gave a theoretical premise to additionally describe its biological roles in response to abiotic stresses particularly drought.

Genome-Wide Analysis and Expression Tendency of Banana (Musa acuminata L.) Calcineurin B-Like (MaCBL) Genes under Potassium Stress

Calcineurin B-like (CBL) proteins are reported to play significant roles in plant development and ion-transport regulation. Potassium shortages are a serious problem in banana cultivation. However, to date, the members of the banana CBL gene family, and their function in regulating potassium stress, remain unclear. In this study, 11 CBL genes were identified from the banana genome and grouped into four groups (Group I–IV) based on their phylogenetic relationships. The genomic features of these MaCBL genes were analyzed, focusing on their gene structures, standpat motifs, chromosomal distributions, and evolutionary history. Expression pattern analysis revealed that the MaCBLs were function-specific. Further qRT-PCR analysis indicated that the presence of MaCBL2 was indeed a response to potassium deficiency stress. The MaCBL2 gene was cloned, and sequence alignment indicated that it contained four elongation factor hand (EF-hand) domains, the conserved N-terminal myristoylation domain “MGCXXS/K(T)” and the “FPSF” motif. Subcellular location analysis showed that MaCBL2 was located in the plasma membrane, nucleus and cytoplasm. The overexpression of MaCBL2 could restore the growth of the yeast mutant R5421 on a K+-deficient medium. The overexpression of MaCBL2 could promote the root length of transgenic seedlings on K+-deficient medium. These findings indicate that MaCBL2 was, in our study, the key gene of the CBL family in responding to potassium deficiency in bananas. Our discoveries have established a considerable basis for the further study and application of MaCBL genes.

Haloferax mediterranei Cells as C50 Carotenoid Factories

Haloarchaea produce C50 carotenoids such as bacterioruberin, which are of biotechnological in-terest. This study aimed to analyze the effect of different environmental and nutritional conditions on the cellular growth and dynamics of carotenoids accumulation in Haloferax mediterranei. The maximum production of carotenoids (40 µg·mL−1) was obtained during the stationary phase of growth, probably due to nutrient-limiting conditions (one-step culture). By seven days of culture, 1 mL culture produced 22.4 mg of dry weight biomass containing 0.18 % (w/w) of carotenoids. On the other hand, carbon-deficient cultures (low C/N ratio) were observed to be optimum for C50 bacterioruberin production by Hfx. mediterranei, but negatively affected the growth of cells. Thus, a two-steps process was evaluated for optimum carotenoids yield. In the first step, a nutri-ent-repleted culture medium enabled the haloarchaea to produce biomass, while in the second step, the biomass was incubated under osmotic stress and in a carbon-deficient medium. Under the conditions used, the obtained biomass contained 0.27% (w/w) of carotenoids after seven days, which accounts for 58.49 µg·mL−1 of carotenoids for a culture with turbidity 14.0.

Calcifying Bacteria Flexibility in Induction of CaCO3 Mineralization

Microbially induced CaCO3 precipitation (MICP) is considered as an alternative green technology for cement self-healing and a basis for the development of new biomaterials. However, some issues about the role of bacteria in the induction of biogenic CaCO3 crystal nucleation, growth and aggregation are still debatable. Our aims were to screen for ureolytic calcifying microorganisms and analyze their MICP abilities during their growth in urea-supplemented and urea-deficient media. Nine candidates showed a high level of urease specific activity, and a sharp increase in the urea-containing medium pH resulted in efficient CaCO3 biomineralization. In the urea-deficient medium, all ureolytic bacteria also induced CaCO3 precipitation although at lower pH values. Five strains (B. licheniformis DSMZ 8782, B. cereus 4b, S. epidermidis 4a, M. luteus BS52, M. luteus 6) were found to completely repair micro-cracks in the cement samples. Detailed studies of the most promising strain B. licheniformis DSMZ 8782 revealed a slower rate of the polymorph transformation in the urea-deficient medium than in urea-containing one. We suppose that a ureolytic microorganism retains its ability to induce CaCO3 biomineralization regardless the origin of carbonate ions in a cell environment by switching between mechanisms of urea-degradation and metabolism of calcium organic salts.

Gm9795 Promotes Inflammation in Non-Alcoholic Steatohepatitis via NF-κB/JNK Pathway by Endoplasmic Reticulum Stress

Background: Non-alcoholic steatohepatitis (NASH) is a key stage in leading development of non-alcoholic simple fatty liver (NAFL) into cirrhosis and even liver cancer. This study aimed at exploring the lncRNA expression profifile in NASH and the biological function of a novel LncRNA-gm9795. Methods: Microarray analysis was performed to compare the expression profifiles of lncRNAs in the liver of NASH, NAFLD and normal mice. Methionine-choline-deficient Medium(MCD) with Lipopolysaccharide(LPS) or palmitic acid（PA）were used to built NASH cell models.The role and mechanism of LncRNA-gm9795 in NASH were explored by knocking down or over-expressing its expression. Results: A total of 381 lncRNAs were found to be not only highly expressed in NAFLD, but also is going to go even higher in NASH. A novel LncRNA-Gm9795 was significantly highly expressed in liver tissues of NASH animal models and NASH cell models. By staining with Nile red, we found that Gm9795 did not affect the fat accumulation of NASH. However, Gm9795 in NASH cell models significantly promoted the expression of TNFα, IL-6, IL-1β, the important inflammatory mediators in NASH. At the same time, we found that Gm9795 upregulated the key molecules in endoplasmic reticulum stress (ERS), while NF-κB/JNK pathways were also activated. When ERS activator Thapsigargin(TG) was introduced in cells with Gm9757 si-RNA, NF-κB and JNK pathways were activated. Conversely, ERS inhibitor Tauroursodeoxycholic(TUDCA) acid inhibited NF-kB and JNK pathways in cells with Gm9795 overexpression plasmid. Conclusion: LncRNA-gm9795 promotes inflammatory response in NASH through NF-kB and JNK pathways by ERS, which might provide theoretical basis for revealing the pathogenesis of NASH and discovering new therapeutic targets

Study on RNA Regulating Iron Transport in Outer Membrane Vesicles of Hypervirulent Klebsiella Pneumoniae

Background: The iron acquisition ability of hypervirulent Klebsiella pneumoniae (hvKP) is an important part of its super virulence mechanism, increasing studies have proved that outer membrane vesicles (OMVs) are involved in the iron acquisition process of bacteria. Thus, we compared the difference in RNA expression in OMVs of hvKP in iron-rich and iron-deficient medium, and explore the possible mechanism of RNA in OMVs involved in hvKP iron acquisition. Results: The results of high-throughput sequencing showed that in iron-deficient medium, there were 239 up-regulated and 89 down-regulated mRNAs in OMVs of hvKP, of which 20 mRNAs related to iron transport was up-regulated, mainly including siderophore synthesis and receptor genes, ATP binding cassette transporter family and iron sulfur cluster. Only two of the differential ncRNAs that regulate these mRNAs are up-regulated, which are lncRNAs.Conclusion: We demonstrated that mRNA and lncRNA in OMVs were directly or indirectly involved in the iron acquisition mechanism of hvKP under iron deficiency environment, which enhanced the adaptive survival ability of hvKP. It provided a basis for further exploring the iron acquisition mechanism of OMVs involved in hvKP.

Manganese Treatment Alleviates Zinc Deficiency Symptoms in Arabidopsis Seedlings

Plant phenotypes caused by mineral deficiencies differ depending on growth conditions. We recently reported that the growth of Arabidopsis thaliana was severely inhibited on MGRL-based zinc (Zn)-deficient medium but not on Murashige–Skoog-based Zn-deficient medium. Here, we explored the underlying reason for the phenotypic differences in Arabidopsis grown on the different media. The root growth and chlorophyll contents reduced by Zn deficiency were rescued by the addition of extra manganese (Mn) during short-term growth (10 or 14 d). However, this treatment did not affect the growth recovery after long-term growth (38 d). To investigate the reason for plant recovery from Zn deficiency, we performed the RNA-seq analysis of the roots grown on the Zn-basal medium and the Zn-depleted medium with/without additional Mn. Principal component analysis of the RNA-seq data showed that the gene expression patterns of plants on the Zn-basal medium were similar to those on the Zn-depleted medium with Mn, whereas those on the Zn-depleted medium without Mn were different from the others. The expression of several transcription factors and reactive oxygen species (ROS)-related genes was upregulated in only plants on the Zn-depleted medium without Mn. Consistent with the gene expression data, ROS accumulation in the roots grown on this medium was higher than those grown in other conditions. These results suggest that plants accumulate ROS and reduce their biomass under undesirable growth conditions, such as Zn depletion. Taken together, this study shows that the addition of extra Mn to the Zn-depleted medium induces transcriptional changes in ROS-related genes, thereby alleviating short-term growth inhibition due to Zn deficiency.

CHO/LY-B cell growth under limiting sphingolipid supply: correlation between lipid composition and biophysical properties of sphingolipid-restricted cell membranes+

ABSTRACTSphingolipids (SL) are ubiquitous in mammalian cell membranes, yet there is little data on the behavior of cells under SL-restriction conditions. LY-B cells derive from a CHO line in which serine palmitoyl transferase (SPT), thus de novo SL synthesis, is suppressed, while maintaining the capacity of taking up and metabolizing exogenous sphingoid bases from the culture medium. In the present study LY-B cells were adapted to grow in a fetal bovine serum (FBS)-deficient medium to avoid external uptake of lipids. The lowest FBS concentration that allowed LY-B cell growth, though at a slow rate, under our conditions was 0.04%, i.e. 250-fold less than the standard (10%) concentration. Cells grown under limiting SL concentrations remained viable for at least 72 h. Enriching with sphingomyelin the SL-deficient medium allowed the recovery of control LY-B cell growth rates. Studies including whole cells, plasma membrane preparations, and derived lipid vesicles were carried out. Laurdan fluorescence was recorded to measure membrane molecular order, showing a significant decrease in the rigidity of LY-B cells, not only in plasma membrane but also in whole cell lipid extract, as a result of SL limitation in the growth medium. Plasma membrane preparations and whole cell lipid extracts were also studied using atomic force microscopy in the force spectroscopy mode. Force measurements demonstrated that lower breakthrough forces were required to penetrate samples obtained from SL-poor LY-B cells than those obtained from control cells. Mass-spectroscopic analysis was also a helpful tool to understand the rearrangement undergone by the LY-B cell lipid metabolism. The most abundant SL in LY-B cells, sphingomyelin, decreased by about 85% as a result of SL limitation in the medium, the bioactive lipid ceramide and the ganglioside precursor hexosylceramide decreased similarly, together with cholesterol. Quantitative SL analysis showed that a 250-fold reduction in sphingolipid supply to LY-B cells led to a 6-fold decrease in membrane sphingolipids, underlining the resistance to changes in composition of these cells. Plasma membrane compositions exhibited similar changes, at least qualitatively, as the whole cells with SL restriction. A linear correlation was observed between the sphingomyelin concentration in the membranes, the degree of lipid order as measured by laurdan fluorescence, and membrane breakthrough forces assessed by atomic force microscopy. Concomitant changes were detected in glycerophospholipids under SL-restriction conditions.

Arabidopsis thaliana Tolerates Iron Deficiency more than Thellungiella Salsuginea by Inducing Metabolic Changes at the Root Level

Several studies have used A. thaliana as a model to identify the physiological and molecular mechanisms underlying iron deficiency tolerance in plants. Here, Arabidopsis thaliana and Thellungiella salsuginea were used to investigate the differential responses to iron deficiency of these two species. Plants were cultivated in hydroponic medium containing 5 or 0 μM Fe, for 10 days. Results showed that rosette biomass was more reduced in T. salsuginea than in A. thaliana when grown on Fe-deficient medium. As a marker for iron deficiency tolerance, the induction of ferric chelate reductase (FCR) and phosphoenolpyruvate carboxylase (PEPC) activities was observed only in A. thaliana roots. In addition, we found that the accumulation of phenolic acids in roots of N1438 ecotype of A. thaliana was stimulated by Fe deficiency. Furthermore, an increase of flavonoids content in the root and exudates was observed under Fe-deficiency in this ecotype. Unlike other abiotic stresses, it appears that iron deficiency effects were more pronounced in Thellungiella than in Arabidopsis. The higher tolerance of the Arabidopsis plant to iron deficiency may be due to the metabolic changes occurring in the roots.

Saksenaea erythrospora infection following a serious sailing accident

Saksenaea erythrospora is a species of the order Mucorales recently described and reported as a cause of human mucormycosis. We report a case of S. erythrospora in a man involved in a serious sailing accident causing deep skin and soft tissue contamination with soil and water. Direct microscopic examination of the clinical sample with Giemsa stains showed hyaline and non-septate hyphae belonging to the order Mucorales. Fungal identification was performed by culture of biopsy material on SDA, and identification of species by floating an agar block containing the fungus in a nutritionally deficient medium consisting of sterile distilled water supplemented with 0.05 % yeast extract; and by sequencing the ITS region of the rDNA. This is the first report to our knowledge of infection with S. erythrospora in Argentina, confirming the presence of this fungus in this country.