The effect of slow-growth strategy on a production of Petunia × hybrida Vilm. microcuttings

Petunia × hybrida Vilm. is a fast-growing ornamental plant that was cultured under varying storage conditions to address seasonal fluctuations in microcutting demand. The effects of storage period (16 to 32 wk), temperature (15 to 23°C), low and high light intensity, sucrose (1 to 5% w/v), and mannitol (0 to 4% w/v) in factorial arrangements were analyzed. Stored and non-stored shoots were compared for microcutting production, harvested twice at 3-wk intervals, and were subsequently transferred to the greenhouse for 17 d. Nearly all plants from 16-wk storage survived well at all treatment conditions and the quality and quantity of microcuttings were enhanced from shoots stored at 15°C and 3% (w/v) sucrose, without mannitol for all storage periods. Another experiment tested 11- to 25-wk storage period with Petunia hybrida ‘Ragtime’ and ‘Suncatcher’ at 12°C and low light intensity. Repeated cycles of microcutting at 2-wk intervals were extended with ex vitro rooting in the greenhouse for 15 d. More and better quality microcuttings were obtained from the second and third cutting cycles than from the first or fourth cycles. By reducing temperature and light intensity, Petunia hybrida was successfully stored for 32 wk (without mannitol). A seasonal schedule with a short production window, followed by cutting large numbers of high-quality shoot-tips, could be affected and efficiently managed through storage. The value of stored shoots was enhanced by extending the number of times a shoot could be cut over repeated cutting cycles with a gain in microcutting quality.

     

Hydrogen peroxide affects abscisic acid binding to ABAP1 in barley aleurones.

Dramatic increases in H2O2 levels have been observed following abscisic acid (ABA) treatment of plant tissues. Following ABA treatment in aleurone cells, H2O2 reached transient levels of approximately 115 micromol/L H2O2. To determine whether ABA perception was modified by such changes, the effect of H2O2 on a recently characterized ABA-binding protein (ABAP1), cloned from barley aleurone layers, was examined. ABA binding to the protein was weakened by H2O2 in a concentration-dependent manner. A concentration of 75 micromol/L H2O2 gave a 50% decline in ABA binding in a reaction following first-order kinetics, indicative of binding-site susceptibility to its microenvironment. We monitored the unfolding of ABAP1 using steady-state and time-resolved tryptophan fluorescence, while following the capacity of ABAP1 to bind ABA. ABA binding decreased by 50% following ABAP1 denaturation with 1 mol/L guanidine hydrochloride or 2 mol/L urea, while the maximum emission spectra (lambda emi) red shifted from 338 to 347 nm at 3.5 mol/L guanidine hydrochloride and 5 mol/L urea. However, only a slight blue shift of lambda emi was observed following either ABAP1 incubation with H2O2 or binding to (+)-ABA (physiologically active ABA). The equilibrium ABA dissociation rate accelerated in the presence of 250 micromol/L H2O2, with the half-time dissociation reduced to 8 min. A comparison of inactivation kinetics and conformational changes shows that inactivation of ABAP1 occurs before any noticeable conformational change. This suggests that the ABA binding site is highly responsive to its microenvironment and is situated in a region that is more flexible than the protein molecule as a whole. The results demonstrate that H2O2, generated by ABA treatment of aleurone layers, is sufficient to affect the ABA-binding capacity of ABAP1, suggesting that this may be another level of control of ABA signal transduction.     

Effect of gamma irradiation on elimination of aflatoxins produced by apple mycoflora in apple fruits

The influence of ionizing radiation on the growth of apple mycoflora and the aflatoxins production was investigated. Four strains of fungal isolates, Aspergillus flavus, A. fumigatuis, A. niger, Penicillium expansum, were used. Four doses of gamma radiation were applied (0.5, 1.0, 1.5 and 2.0 KGy). The elimination of aflatoxins under selected conditions was detected by using HPLC techniques. Doses of 0.5 KGy stimulated the production of aflatoxins by all fungi tested while 1.0-2.0 KGy reduced the aflatoxins production. The studies were also carried out to investigate the effect of pre- and post-inoculation of both irradiated and non-irradiated fungal spores on irradiated and non-irradiated apples. The results showed the necessity of irradiation of fresh apple fruits followed by good preservation conditions. The results showed also that the effect of radiation is influences on the apple mycoflora producing aflatoxins and not the apple itself.     

Integrin alpha2beta1 inhibits Fas-mediated apoptosis in T lymphocytes by protein phosphatase 2A-dependent activation of the MAPK/ERK pathway

The mechanisms by which T lymphocytes escape apoptosis during their activation are still poorly defined. In this study, we elucidated the intracellular signaling pathways through which beta1 integrins modulate Fas-mediated apoptosis in T lymphocytes. In experiments done in Jurkat T cells and activated peripheral blood T lymphocytes, engagement of alpha2beta1 integrin with collagen type I (Coll I) was found to significantly reduce Fas-induced apoptosis and caspase-8 activation; Annexin V binding and DNA fragmentation were reduced by approximately 42 and 38%, respectively. We demonstrated that the protective action of Coll I does not require new protein synthesis but was dependent on the activation of the MAPK/Erk pathway. Furthermore, we found that activation of protein phosphatase 2A (PP2A) by Coll I was required for both Coll I-mediated activation of Erk, and inhibition of Fas-induced caspase-8 activation and apoptosis. Other ligands of beta1 integrins, fibronectin (Fbn), and laminin (Lam), did not sustain significant Erk activation and had no effect on Fas-induced apoptosis. Taken together, these results provide the first evidence of a PP2A-dependent activation of the MAPK/Erk pathway downstream of alpha2beta1 integrin, which has a functional role in regulating Fas-mediated apoptosis in T lymphocytes. As such, this study emphasizes the potential importance that Coll I interactions may have on the control of T lymphocyte homeostasis and their persistence in chronic inflammatory diseases.     

Dynamics of the cytokine messenger RNA expression pattern in the liver of baboons infected with Schistosoma mansoni

Periovular granulomas are the major lesions in baboons infected with Schistosoma mansoni. Temporal Northern blot analysis of cytokine messenger RNA (mRNA) expression in granulomatous baboon livers demonstrated tissue-specific expression. Interleukin 1 beta (IL-1beta, IL-6, tumor necrosis factor alpha, and migration inhibitory factor (MIF) mRNAs were expressed strongly at week 6 of infection and decayed thereafter, whereas interferon gamma (IFN-gamma), IL-2, IL-10, and IL-12 mRNAs were first expressed at week 12, with IFN-gamma and IL-12 mRNA expression persisting until week 17. IL-4 and IL-5 mRNAs first appeared at week 12, with IL-4 persisting unchanged and IL-5 increasing by week 17. Thus, egg deposition induced strong hepatic expression of proinflammatory and downregulatory cytokines. The cooccurrence of IL-2, IFN-gamma, IL-4, and IL-5 mRNAs at week 12 confirms that baboons, like humans, show a mixed type 1-type 2 cytokine response. When granulomas had become smaller at 17 wk, IFN-gamma, IL-4, and IL-5 were the only cytokine mRNAs that were expressed strongly, implicating them in granuloma modulation. The early expression of MIF mRNA and MIF's role as the main counterregulator of glucocorticoid immunosuppression ties in with our earlier demonstrations of circulating adrenal steroids changing with the progression of schistosomiasis in baboons and of proinflammatory cytokine mRNA expression in the hypothalamic-pituitary-adrenal axis tissues of infected baboons. Together, these data imply neuroendocrinological influences on disease progression in schistosomiasis.     

Visual Cycle Modulation as an Approach toward Preservation of Retinal Integrity

Increased exposure to blue or visible light, fluctuations in oxygen tension, and the excessive accumulation of toxic retinoid byproducts places a tremendous amount of stress on the retina. Reduction of visual chromophore biosynthesis may be an effective method to reduce the impact of these stressors and preserve retinal integrity. A class of non-retinoid, small molecule compounds that target key proteins of the visual cycle have been developed. The first candidate in this class of compounds, referred to as visual cycle modulators, is emixustat hydrochloride (emixustat). Here, we describe the effects of emixustat, an inhibitor of the visual cycle isomerase (RPE65), on visual cycle function and preservation of retinal integrity in animal models. Emixustat potently inhibited isomerase activity in vitro (IC₅₀ = 4.4 nM) and was found to reduce the production of visual chromophore (11-cis retinal) in wild-type mice following a single oral dose (ED₅₀ = 0.18 mg/kg). Measure of drug effect on the retina by electroretinography revealed a dose-dependent slowing of rod photoreceptor recovery (ED₅₀ = 0.21 mg/kg) that was consistent with the pattern of visual chromophore reduction. In albino mice, emixustat was shown to be effective in preventing photoreceptor cell death caused by intense light exposure. Pre-treatment with a single dose of emixustat (0.3 mg/kg) provided a ~50% protective effect against light-induced photoreceptor cell loss, while higher doses (1–3 mg/kg) were nearly 100% effective. In Abca4-/- mice, an animal model of excessive lipofuscin and retinoid toxin (A2E) accumulation, chronic (3 month) emixustat treatment markedly reduced lipofuscin autofluorescence and reduced A2E levels by ~60% (ED₅₀ = 0.47 mg/kg). Finally, in the retinopathy of prematurity rodent model, treatment with emixustat during the period of ischemia and reperfusion injury produced a ~30% reduction in retinal neovascularization (ED₅₀ = 0.46mg/kg). These data demonstrate the ability of emixustat to modulate visual cycle activity and reduce pathology associated with various biochemical and environmental stressors in animal models. Other attributes of emixustat, such as oral bioavailability and target specificity make it an attractive candidate for clinical development in the treatment of retinal disease.     

SARS‐CoV‐2 nucleocapsid protein phase‐separates with RNA and with human hnRNPs

Tightly packed complexes of nucleocapsid protein and genomic RNA form the core of viruses and assemble within viral factories, dynamic compartments formed within the host cells associated with human stress granules. Here, we test the possibility that the multivalent RNA‐binding nucleocapsid protein (N) from severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) condenses with RNA via liquid–liquid phase separation (LLPS) and that N protein can be recruited in phase‐separated forms of human RNA‐binding proteins associated with SG formation. Robust LLPS with RNA requires two intrinsically disordered regions (IDRs), the N‐terminal IDR and central‐linker IDR, as well as the folded C‐terminal oligomerization domain, while the folded N‐terminal domain and the C‐terminal IDR are not required. N protein phase separation is induced by addition of non‐specific RNA. In addition, N partitions in vitro into phase‐separated forms of full‐length human hnRNPs (TDP‐43, FUS, hnRNPA2) and their low‐complexity domains (LCs). These results provide a potential mechanism for the role of N in SARS‐CoV‐2 viral genome packing and in host‐protein co‐opting necessary for viral replication and infectivity.     

Co-Culture of Human Bronchial Fibroblasts and CD4+ T Cells Increases Th17 Cytokine Signature

Background

Airway inflammation is an important characteristic of asthma and has been associated with airway remodelling and bronchial hyperreactivity. The mucosal microenvironment composed of structural cells and highly specialised extracellular matrix is able to amplify and promote inflammation. This microenvironment leads to the development and maintenance of a specific adaptive response characterized by Th2 and Th17. Bronchial fibroblasts produce multiple mediators that may play a role in maintaining and amplifying this response in asthma.

Objective

To investigate the role of bronchial fibroblasts obtained from asthmatic subjects and healthy controls in regulating Th17 response by creating a local micro-environment that promotes this response in the airways.

Methods

Human bronchial fibroblasts and CD4⁺T cells were isolated from atopic asthmatics and non-atopic healthy controls. CD4⁺T were co-cultured with bronchial fibroblasts of asthmatic subjects and healthy controls. RORc gene expression was detected by qPCR. Phosphorylated STAT-3 and RORγt were evaluated by western blots. Th17 phenotype was measured by flow cytometry. IL-22, IL17, IL-6 TGF-β and IL1-β were assessed by qPCR and ELISA.

Results

Co-culture of CD4⁺T cells with bronchial fibroblasts significantly stimulated RORc expression and induced a significant increase in Th17 cells as characterized by the percentage of IL-17⁺/CCR6⁺ staining in asthmatic conditions. IL-17 and IL-22 were increased in both normal and asthmatic conditions with a significantly higher amount in asthmatics compared to controls. IL-6, IL-1β, TGF-β and IL-23 were significantly elevated in fibroblasts from asthmatic subjects upon co-culture with CD4⁺T cells. IL-23 stimulates IL-6 and IL-1β expression by bronchial fibroblasts.

Conclusion

Interaction between bronchial fibroblasts and T cells seems to promote specifically Th17 cells profile in asthma. These results suggest that cellular interaction particularly between T cells and fibroblasts may play a pivotal role in the regulation of the inflammatory response in asthma.