Micromorphological studies of the leaf epidermis of Iranian Cotoneaster Medik

In this study, micromorphological features of the leaf epidermal cells of 17 species of Iranian Cotoneaster were determined. The studied species were compared with each other and with phylogenetic relationships established by previous studies. Three populations of C. integerrimus and C. multiflorus were studied as representatives of C. subgen. Cotoneaster and Chaenopetalum, respectively. To evaluate quantitative and qualitative characters, multiple correspondence analysis (MCA) and factor analysis of mixed data (FAMD) were performed. Finally, relationships among the taxa were illustrated by hierarchical clustering analysis. Three stomatal types were identified, i.e. anomocytic, stephanocytic and actino‐stephanocytic. The wax and cuticle density was higher in species from semi‐moist habitats than in those from dry and semi‐dry habitats. The patterns formed by the anticlinal walls of the epidermal cells were sinuous, repand and straight‐curved. Interestingly, there was a significant relationship between the length of leaves, the density of the indumentum and the pattern formed by the anticlinal cell walls. The leaves of species with large leaves also have lower hair density and more curved anticlinal cell walls. It appears probable that climatic conditions affected the evolution of leaf micro‐morphological characters during the early diversification of the genus, but that these characters have subsequently been permanently fixed by phylogenetic constraints and thus appear diagnostic for extant species.     

A possible role for C4 photosynthetic enzymes in tolerance of Zea mays to NaCl

Treatment of 14-day-old maize cultivars (Hybrid351 and Giza2) with 250 mM NaCl significantly reduced shoot fresh and dry weights and protein content during the subsequent 12 days. The magnitude of reduction was more pronounced in Giza than Hybrid. Both cultivars contained converging levels of protein for the enzymes phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), pyruvate phosphate dikinase (PPDK) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) under normal conditions; however, NaCl led to increase these levels in Hybrid and decrease them in Giza. Moreover, NaCl significantly inhibited the activities of PEPC, MDH and PPDK in both cultivars during the first 2 days, thereafter the inhibition nullified only in Hybrid; nonetheless, Rubisco was the least affected enzyme in both cultivars. In addition, NaCl slightly increased V _max of PEPC, MDH and PPDK in Hybrid with no change in K _m; nevertheless V _max dropped in Giza with an increase in K _m of only PEPC and MDH. Also K _cat, K _cat/K _m and V _max/K _m of all enzymes were lower in treated Giza than in treated Hybrid. The increased V _max of all enzymes in only Hybrid by NaCl confirms that they were synthesised more in Hybrid than in Giza. However, the decreased V _max in Giza concomitant with the increased K _m points to an interference of salinity with synthesis of enzymes and their structural integrity. This would lead to a noncompetitive inhibition for the enzymes. These findings declare that maize tolerance to NaCl was larger in Hybrid compared to Giza due to a role for C4 enzymes.     

Impact of inflammatory cytokine and adipokine gene variations in the development of HIV-associated lipodystrophy

Cytokines affect lipid and glucose metabolism and also alter the body's habitus. They play a role in the development of lipodystrophy syndrome. Adipocytes secrete the pro-inflammatory cytokines IL-1, TNF-α and IL-6. The plasma cytokine concentration is associated with the percentage and distribution of fat tissue in the body. The metabolic disturbances are strongly associated with increased levels of pro-inflammatory cytokines (IL-1, IL-6 and TNF-α). Plasma levels of cytokines such as TNF-α, IL-6 and leptin were found to be increased while plasma resistin levels were found to be variable in patients suffering from obesity and type II diabetes mellitus. Until now, limited information has been available on the polymorphism of cytokine and adipokine genes in patients of HIV-associated lipodystrophy (HIVLD), which can contribute to individual variations in susceptibility to metabolic diseases, especially to HIVLD. Hence, we studied the association of cytokine and adipokine gene polymorphisms in various diseases and their impact on HIVLD. We carry out an extensive search using several databases, including PubMed, EMBASE and Google Scholar. The distribution of cytokine and adipokine gene polymorphisms and their expression levels varied among various populations. We examined the variants of cytokine and adipokine genes, which can contribute to individual variations in susceptibility to metabolic diseases, especially to HIVLD. In the current review, we present a brief account of the risk factors of HIVLD, the pathogenesis of HIVLD and the polymorphism of cytokine and adipokine genes in various diseases with special reference to their impact on HIVLD.     

Protective effect of diosmin against doxorubicin-induced nephrotoxicity

Doxorubicin (Dox) is an anthracycline antibiotic that is primarily used for treating various solid tumors including that of pulmonary, ovary, breast, uterine, cervix, and several blood cancers. However, nephrotoxicity associated with Dox treatment limits its clinical use. Administration of Dox in combination with compounds exhibiting antioxidant properties are being used to minimize the side effects of Dox. Diosmin is a flavonoid glycoside with numerous beneficial properties that is found in the pericarp of many citrus fruits. Diosmin has demonstrated antioxidant, anti-inflammatory, and anti-apoptotic effects in response to various insults, although the exact mechanism remains unknown. Therefore, this study was designed to evaluate the effect of diosmin in preventing kidney damage in response to Dox treatment. Male Wistar rats were randomly divided into four groups: control group, Dox group (20 mg/kg, i.p.), Dox plus low-dose diosmin group (100 mg/kg orally), and Dox plus high-dose diosmin group (200 mg/kg orally). A single intraperitoneal injection of Dox resulted in kidney damage as evidenced by significant alterations in kidney markers, histological abnormalities, and the attenuation of antioxidant defense mechanisms (GSH, SOD, and CAT). Moreover, Dox treatment significantly altered the expression of oxidative stress, inflammatory, and anti-apoptotic protein markers. Diosmin pretreatment alleviated Dox-induced nephrotoxicity by ameliorating the antioxidant mechanism, decreasing inflammation and apoptosis, and restoring kidney architecture. In conclusion, our results indicate that diosmin is a promising therapeutic agent for the prevention of nephrotoxicity associated with DOX.     

CYP52X1, representing new cytochrome P450 subfamily, displays fatty acid hydroxylase activity and contributes to virulence and growth on insect cuticular substrates in entomopathogenic fungus Beauveria bassiana

Infection of insects by the entomopathogenic fungus Beauveria bassiana proceeds via attachment and penetration of the host cuticle. The outermost epicuticular layer or waxy layer of the insect represents a structure rich in lipids including abundant amounts of hydrocarbons and fatty acids. A member of a novel cytochrome P450 subfamily, CYP52X1, implicated in fatty acid assimilation by B. bassiana was characterized. B. bassiana targeted gene knockouts lacking Bbcyp52x1 displayed reduced virulence when topically applied to Galleria mellonella, but no reduction in virulence was noted when the insect cuticle was bypassed using an intrahemoceol injection assay. No significant growth defects were noted in the mutant as compared with the wild-type parent on any lipids substrates tested including alkanes and fatty acids. Insect epicuticle germination assays, however, showed reduced germination of ΔBbcyp52x1 conidia on grasshopper wings as compared with the wild-type parent. Complementation of the gene-knock with the full-length gene restored virulence and insect epicuticle germination to wild-type levels. Heterologous expression of CYP52X1 in yeast was used to characterize the substrate specificity of the enzyme. CYP52X1 displayed the highest activity against midrange fatty acids (C12:0 and C14:0) and epoxy stearic acid, 4-8-fold lower activity against C16:0, C18:1, and C18:2, and little to no activity against C9:0 and C18:0. Analyses of the products of the C12:0 and C18:1 reactions confirmed NADPH-dependent regioselective addition of a terminal hydroxyl to the substrates (ω-hydroxylase). These data implicate CYP52X1 as contributing to the penetration of the host cuticle via facilitating the assimilation of insect epicuticle lipids.     

Effect of kinetin on photosynthetic activity and carbohydrate content in waterlogged or seawater-treated Vigna sinensis and Zea mays plants

ABSTRACT

Waterlogging decreased carotenoid content of Vigna sinensis and Zea mays, whilst salinity provoked increases in the former and decreases in the latter. Both treatments showed significant reductions in chlorophyll content and in photosynthetic activity (Hill reaction and ¹⁴CO₂-light fixation). Meanwhile, a significant decrease in the activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was detected in both plants. These reductions could result in losses in the photosynthetic activity with a drop in the net formation of carbohydrates. Waterlogging markedly increased glucose and sucrose in shoots and roots of both species throughout the experimental period but greatly decreased polysaccharides, whilst salinity reduced all carbohydrate fractions. Foliar application of 50 ppm kinetin to treated plants mostly counterbalanced the observed changes in pigments, as well as in the Hill reaction and ¹⁴CO₂ assimilation. Kinetin also rendered carbohydrate levels in shoots and roots of treated plants and activity of Rubisco closer to control values. The increased levels of glucose and sucrose concomitant with decreased polysaccharides might point to a block in their transport rather than to an over-production. Kinetin counterbalanced the effects of waterlogging or salinity on photosynthetic activity, probably through enhanced production of enzyme and/or delay of senescence.     

Reduced efficacy of multiple doses of CpG-matured dendritic cell tumor vaccine in an experimental model

CpG motifs have been advanced as agents that stimulate the maturation of DCs for immunotherapy. The present study tested the hypothesis that multiple doses of CpG-matured DC vaccine would be efficacious for complete eradication of experimentally-induced tumor. Accordingly, WEHI164 cells were implanted subcutaneously in the flank of BALB/c mice. During DC culture, tumor lysate was added to immature DCs followed by addition of CpG or non-CpG control 4–6 h later. A total of three doses of CpG or non-CpG control-matured DCs were injected around tumors. The results showed that multiple doses of CpG-matured DCs led to considerable decrease in cytotoxicity of lymphocytes and significantly increased tumor growth rate compared to a single dose. Further, mice which received three doses of the vaccine also displayed significant FoxP3 in tumor tissue. In conclusion, multiple doses of CpG-matured DCs exhibited decreased anti-tumor immunity in association with increased expression of FoxP3.     

High-throughput insertion mutagenesis and functional screening in the entomopathogenic fungus Beauveria bassiana

The entomopathogenic fungus Beauveria bassiana displays a broad insect host range and serves as a model for examining host-pathogen interactions. Rapid construction and screening of random-insertion mutants of B. bassiana provides a powerful tool to dissect the molecular mechanisms of fungal virulence. LiAc/DMSO treated B. bassiana blastospores were found to be highly competent to transformation using linear DNA and a polyethylene glycol-based method. Selection on cellophane-layered Czapek-Dox agar at a lowered pH (from 7.5 to 6.3) greatly decreased background growth of non-transformed cells and improved screening of transformants. Optimization of the protocol using integration of the bar phosphinothricin resistance gene resulted in high transformation rates (200-250 transformants/μg DNA/10⁸ cells). A collection of ∼4000 insertion mutants was examined via high-throughput screens for hydrocarbon utilization. One mutant was isolated that grew poorly on both n-hexadecane and tributyrin. The random insertion site was mapped to a gene that displayed homology to vitamin H (biotin)/tartrate transporters. Insect bioassays using Galleria mellonella as the target host revealed decreased virulence in the mutant. This system provides a simple and rapid method for the generation and screening of insertion mutants and should expand our ability to genetically analyze the B. bassiana lifestyle.     

Pyrokinin β-neuropeptide affects necrophoretic behavior in fire ants (S. invicta), and expression of β-NP in a mycoinsecticide increases its virulence

Fire ants are one of the world's most damaging invasive pests, with few means for their effective control. Although ecologically friendly alternatives to chemical pesticides such as the insecticidal fungus Beauveria bassiana have been suggested for the control of fire ant populations, their use has been limited due to the low virulence of the fungus and the length of time it takes to kill its target. We present a means of increasing the virulence of the fungal agent by expressing a fire ant neuropeptide. Expression of the fire ant (Solenopsis invicta) pyrokinin β-neuropeptide (β-NP) by B. bassiana increased fungal virulence six-fold towards fire ants, decreased the LT(50), but did not affect virulence towards the lepidopteran, Galleria mellonella. Intriguingly, ants killed by the β-NP expressing fungus were disrupted in the removal of dead colony members, i.e. necrophoretic behavior. Furthermore, synthetic C-terminal amidated β-NP but not the non-amidated peptide had a dramatic effect on necrophoretic behavior. These data link chemical sensing of a specific peptide to a complex social behavior. Our results also confirm a new approach to insect control in which expression of host molecules in an insect pathogen can by exploited for target specific augmentation of virulence. The minimization of the development of potential insect resistance by our approach is discussed.