Virulence and pathogenicity of Candida albicans is enhanced in biofilms containing oral bacteria

This study examined the influence of bacteria on the virulence and pathogenicity of candidal biofilms. Mature biofilms (Candida albicans-only, bacteria-only, C. albicans with bacteria) were generated on acrylic and either analysed directly, or used to infect a reconstituted human oral epithelium (RHOE). Analyses included Candida hyphae enumeration and assessment of Candida virulence gene expression. Lactate dehydrogenase (LDH) activity and Candida tissue invasion following biofilm infection of the RHOE were also measured. Candida hyphae were more prevalent (p < 0.05) in acrylic biofilms also containing bacteria, with genes encoding secreted aspartyl-proteinases (SAP4/SAP6) and hyphal-wall protein (HWP1) up-regulated (p < 0.05). Candida adhesin genes (ALS3/EPA1), SAP6 and HWP1 were up-regulated in mixed-species biofilm infections of RHOE. Multi-species infections exhibited higher hyphal proportions (p < 0.05), up-regulation of IL-18, higher LDH activity and tissue invasion. As the presence of bacteria in acrylic biofilms promoted Candida virulence, consideration should be given to the bacterial component when managing denture biofilm associated candidoses.     

Neotyphodium endophyte strain and superoxide dismutase activity in perennial ryegrass plants under water deficit

The presence of Neotyphodium endophyte in forage grass tillers has been associated with increased tolerance of abiotic stresses. The effect of four endophyte treatments (plants with three different strains of Neotyphodium lolii compared with plants without endophyte) on superoxide dismutase (SOD) (EC1.15.1.1) activity in Lolium perenne cv ‘Grasslands Samson’ was measured under high and low dehydration regimes in a glasshouse experiment. SOD activity was assayed by a microplate method utilising the inhibition of reduction of a tetrazolium dye by superoxide radicals. A progressive increase in dehydration over 2 weeks reduced shoot fresh weight, dry weight and shoot water content for high, compared with low, moisture-stressed plants. Mean shoot fresh weight was significantly lower for plants with strain AR37 endophyte than for plants with strain AR1 endophyte, wild-type or endophyte-free plants, but there was no interaction between endophyte treatment and dehydration treatment. There were no differences in mean SOD activity between the dehydration treatments, and the four endophyte treatments at any of the harvests. All harvest mean SOD levels for plants in both stress groups, however, were significantly different from the preceding harvest value. Between the first and second week of moisture stress there was a significant endophyte by harvest interaction for mean percentage change in SOD activity when activity in plants with wild-type strain endophyte increased more rapidly than in AR1, AR37 or endophyte-free plants. The results are in agreement with earlier reports suggesting that Neotyphodium endophytes do not have major effects on the water stress physiology of perennial ryegrass, although water deficits applied were not extreme.     

A novel melatonin agonist Neu-P11 facilitates memory performance and improves cognitive impairment in a rat model of Alzheimer' disease

Previous studies have shown that melatonin is implicated in modulating learning and memory processing. Melatonin also exerts neuroprotective activities against Aβ-induced injury in vitro and in vivo. Neu-P11 (piromelatine, N-(2-(5-methoxy-1H-indol-3-yl)ethyl)-4-oxo-4H-pyran-2-carboxamide) is a novel melatonin (MT1/MT2) receptor agonist and a serotonin 5-HT1A/1D receptor agonist recently developed for the treatment of insomnia. In the present study we firstly investigated whether Neu-P11 and melatonin enhance memory performance in the novel object recognition (NOR) task in rats, and then assessed whether Neu-P11 and melatonin improve neuronal and cognitive impairment in a rat model of Alzheimer' disease (AD) induced by intrahippocampal Aβ_(1–42) injection. The results showed that a single morning or afternoon administration of Neu-P11 enhanced object recognition memory measured at 4 or 24 h after training. Melatonin was effective in the memory facilitating effects only when administered in the afternoon. Further results showed that intrahippocampal Aβ_(1–42) injection resulted in hippocampal cellular loss, as well as decreased learning ability and memory in the Y maze and NOR tasks in rats. Neu-P11 but not melatonin attenuated cellular loss and cognitive impairment in the rat AD model. The current data suggest that Neu-P11 may serve as a novel agent for the treatment of AD.     

Identification of novel caspase/autophagy‐related gene switch to cell fate decisions in breast cancers

Objectives

Caspases, a family of cysteine proteases with unique substrate specificities, contribute to apoptosis, whereas autophagy‐related genes (ATGs) regulate cytoprotective autophagy or autophagic cell death in cancer. Accumulating evidence has recently revealed underlying mechanisms of apoptosis and autophagy; however, their intricate relationships still remain to be clarified. Identification of caspase/ATG switches between apoptosis and autophagy may address this problem.

Materials and methods

Identification of caspase/ATG switches was carried out using a series of elegant systems biology & bioinformatics approaches, such as network construction, hub protein identification, microarray analyses, targeted microRNA prediction and molecular docking.

Results

We computationally constructed the global human network from several online databases and further modified it into the basic caspase/ATG network. On the basis of apoptotic or autophagic gene differential expressions, we identified three molecular switches [including androgen receptor, serine/threonine‐protein kinase PAK‐1 (PAK‐1) and mitogen‐activated protein kinase‐3 (MAPK‐3)] between certain caspases and ATGs in human breast carcinoma MCF‐7 cells. Subsequently, we identified microRNAs (miRNAs) able to target androgen receptor, PAK‐1 and MAPK‐3, respectively. Ultimately, we screened a range of small molecule compounds from DrugBank, able to target the three above‐mentioned molecular switches in breast cancer cells.

Conclusions

We have systematically identified novel caspase/ATG switches involved in miRNA regulation, and predicted targeted anti‐cancer drugs. These findings may uncover intricate relationships between apoptosis and autophagy and thus provide further new clues towards possible cancer drug discovery.

     

Gene cloning and functional analysis of yellow green leaf3 (ygl3) gene during the whole-plant growth stage in rice

Chlorophyll is an important photosynthetic pigment in the process of photosynthesis in plants and photosynthetic bacteria. Genes involved in chlorophyll biosynthesis in Arabidopsis and photosynthetic bacteria have been well documented. In rice, however, these genes have not been fully annotated. In this paper, a yellow-green leaf gene, yellow green leaf3 (ygl3) was cloned and analyzed. ygl3 encodes magnesium chelation ChlD (D) subunit, a key enzyme for chlorophyll synthesis, resulting in a yellow-green leaf phenotype in all growth stages in rice. Expression content of ygl3 is highest in the leaf blades, followed by the leaf sheaths, while there is virtually no expression of the gene in the stems and seeds. The sub-cellular structure and protein content of the photosynthetic system of the ygl3 mutant were revealed by transmission electron microscopy, BN-PAGE, and western blotting. The results show that the mutation of the ygl3 gene indirectly leads to a decrease in the protein content of the photosynthetic system and severely obstructs the formation of granum thylakoids.     

Three‐dimensional neural differentiation of embryonic stem cells with ACM induction in microfibrous matrices in bioreactors

The clinical use of pluripotent stem cell (PSC)‐derived neural cells requires an efficient differentiation process for mass production in a bioreactor. Toward this goal, neural differentiation of murine embryonic stem cells (ESCs) in three‐dimensional (3D) polyethylene terephthalate microfibrous matrices was investigated in this study. To streamline the process and provide a platform for process integration, the neural differentiation of ESCs was induced with astrocyte‐conditioned medium without the formation of embryoid bodies, starting from undifferentiated ESC aggregates expanded in a suspension bioreactor. The 3D neural differentiation was able to generate a complex neural network in the matrices. When compared to 2D differentiation, 3D differentiation in microfibrous matrices resulted in a higher percentage of nestin‐positive cells (68% vs. 54%) and upregulated gene expressions of nestin, Nurr1, and tyrosine hydroxylase. High purity of neural differentiation in 3D microfibrous matrix was also demonstrated in a spinner bioreactor with 74% nestin + cells. This study demonstrated the feasibility of a scalable process based on 3D differentiation in microfibrous matrices for the production of ESC‐derived neural cells. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1013–1022, 2013     

Contribution of cytoskeletal elements to the axonal mechanical properties

Background

Microtubules, microfilaments, and neurofilaments are cytoskeletal elements that affect cell morphology, cellular processes, and mechanical structures in neural cells. The objective of the current study was to investigate the contribution of each type of cytoskeletal element to the mechanical properties of axons of dorsal root and sympathetic ganglia cells in chick embryos.

Results

Microtubules, microfilaments, and neurofilaments in axons were disrupted by nocodazole, cytochalasin D, and acrylamide, respectively, or a combination of the three. An atomic force microscope (AFM) was then used to compress the treated axons, and the resulting corresponding force-deformation information was analyzed to estimate the mechanical properties of axons that were partially or fully disrupted.

Conclusion

We have found that the mechanical stiffness was most reduced in microtubules-disrupted-axons, followed by neurofilaments-disrupted- and microfilaments-disrupted-axons. This suggests that microtubules contribute the most of the mechanical stiffness to axons.

     

Reducing AsA Leads to Leaf Lesion and Defence Response in Knock-Down of the AsA Biosynthetic Enzyme GDP-D-Mannose Pyrophosphorylase Gene in Tomato Plant

As a vital antioxidant, L-ascorbic acid (AsA) affects diverse biological processes in higher plants. Lack of AsA in cell impairs plant development. In the present study, we manipulated a gene of GDP-mannose pyrophosphorylase which catalyzes the conversion of D-mannose-1-P to GDP-D-mannose in AsA biosynthetic pathway and found out the phenotype alteration of tomato. In the tomato genome, there are four members of GMP gene family and they constitutively expressed in various tissues in distinct expression patterns. As expected, over-expression of SlGMP3 increased total AsA contents and enhanced the tolerance to oxidative stress in tomato. On the contrary, knock-down of SlGMP3 significantly decreased AsA contents below the threshold level and altered the phenotype of tomato plants with lesions and further senescence. Further analysis indicated the causes for this symptom could result from failing to instantly deplete the reactive oxygen species (ROS) as decline of free radical scavenging activity. More ROS accumulated in the leaves and then triggered expressions of defence-related genes and mimic symptom occurred on the leaves similar to hypersensitive responses against pathogens. Consequently, the photosynthesis of leaves was dramatically fallen. These results suggested the vital roles of AsA as an antioxidant in leaf function and defence response of tomato.