Correlation between interaction strengths drives stability in large ecological networks

Food webs have markedly non‐random network structure. Ecologists maintain that this non‐random structure is key for stability, since large random ecological networks would invariably be unstable and thus should not be observed empirically. Here we show that a simple yet overlooked feature of natural food webs, the correlation between the effects of consumers on resources and those of resources on consumers, substantially accounts for their stability. Remarkably, random food webs built by preserving just the distribution and correlation of interaction strengths have stability properties similar to those of the corresponding empirical systems. Surprisingly, we find that the effect of topological network structure on stability, which has been the focus of countless studies, is small compared to that of correlation. Hence, any study of the effects of network structure on stability must first take into account the distribution and correlation of interaction strengths.     

Chrysin and Capsaicin induces premature senescence and apoptosis via mitochondrial dysfunction and p53 elevation in Cervical cancer cells

Current studies are focusing on the anti-cancerous properties of natural bioactive compounds, primarily those included in the human diet. These compounds have the potential to alter the redox balance that can hinder cancer cell's growth. In cancer cells, an abnormal rate of ROS production is balanced with higher antioxidant activities, which if not maintained, results in cancer cells being prone to cell death due to oxidative stress. Here, we have analyzed the effects of Chrysin and Capsaicin on the HeLa cells viability and cellular redox signaling. Both these compounds stimulate cellular and mitochondrial ROS overproduction that perturbs the cellular redox state and results in mitochondrial membrane potential loss. Apart from this, these compounds induce cell cycle arrest and induce premature senescence, along with the overexpression of p21, p53, and p16 protein at lower concentration treatment of Chrysin or Capsaicin. Moreover, at higher concentration treatment with these compounds, pro-apoptotic activity was observed with the high level of Bax and cleaved caspase-3 along with suppression of the Bcl-2 protein levels. In-Silico analysis with STITCH v5 also confirms the direct interaction of Chrysin and Capsaicin with target protein p53. This suggests that Chrysin and Capsaicin trigger an increase in mitochondrial ROS, and p53 interaction leading to premature senescence and apoptosis in concentration dependent manner and have therapeutic potential for cancer treatment.     

Auxin-like activity of extract from hypertrophied tissue of <Emphasis Type="Italic">Acacia eburnea</Emphasis> infected with <Emphasis Type="Italic">Ravenelia esculenta</Emphasis>

Ravenelia esculenta Naras. and Thirum. is a rust, pathogenic to Acacia eburnea Willd. The infection leads to hypertrophy changing the morphology with bizarre shapes of plant organs. Healthy and infected tissues were subjected to extraction of IAA and indole derivatives and were estimated by spectrophotometric methods. The hypertrophy produced was presumed to be due to increase in the indole-3-acetic acid (IAA) content in the infected tissue, however, the amount of IAA in infected tissues decreased with the progression of disease. Concomitantly, the infected tissue showed the presence of a novel, slow migrating, indole derivative on TLC. Cultured shoot tips of Withania somnifera were dosed with the methanolic extract of the infected hypertrophied tissue (MEHT) (0.25, 0.5, 0.75, 1.00 and 1.25 mg/l). The stimulation in shoot growth along with profuse rooting was observed in a dose dependent manner with maximum at 1.00 and 1.25 mg/l concentration.     

Anti-biofilm potential of a glycolipid surfactant produced by a tropical marine strain of Serratia marcescens

A tropical marine bacterium isolated from the hard coral, Symphyllia sp. was identified as Serratia marcescens on the basis of morphological, biochemical and 16S rDNA analysis. The bacterium showed antimicrobial activity towards the pathogens Candida albicans and Pseudomonas aeruginosa and the marine biofouling bacterium Bacillus pumilus. S. marcescens displayed biosurfactant activity as evidenced by drop collapse, blood hemolysis and surface tension reduction (52.0-27 mN m(-1)). The active compound was purified by solvent extraction and silicic acid chromatography. Characterization was by thin layer chromatography, gas chromatography mass spectroscopy (GC-MS), Fourier transform infrared (FTIR) spectroscopy and (1)H as well as (13)C nuclear magnetic resonance (NMR) analysis. The surfactant was found to be a glycolipid composed of glucose and palmitic acid. The glycolipid prevented adhesion of C. albicans BH, P. aeruginosa PAO1 and B. pumilus TiO1. The glycolipid also disrupted preformed biofilms of these cultures in microtitre plates. Confocal laser scanning microscopy and electron microscopy confirmed the effective removal of biofilms from glass surfaces. The glycolipid derived from S. marcescens could thus serve as a potential anti-biofilm agent.     

A Novel Folate-Targeted Nanoliposomal System of Doxorubicin for Cancer Targeting

Targeted drug delivery systems for cancer improves anti-tumor efficacy and reduces systemic toxicity by restricting availability of cytotoxic drugs within tumors. Targeting moieties, such as natural ligands (folic acid, transferrin, and biotin) which are overexpressed on tumors, have been used to enhance liposome-encapsulated drug accumulation within tumors and resulted in better control. In this report, we explored the scope of targeting ligand folic acid, which is incorporated in liposome systems using folic acid-modified cholesterol (CPF), enabled highly selective tumor-targeted delivery of liposome-encapsulated doxorubicin and resulted in increased cytotoxicity within tumors. Folate-tagged poloxamer-coated liposomes (FDL) were found to have significantly higher cellular uptake than conventional poloxamer-coated liposomes (DL), as confirmed by fluorometric analysis in B16F10 melanoma cells. Biodistribution study of the radiolabeled liposomal system indicated the significantly higher tumor uptake of FDL as compared to DL. Anti-tumor activity of FDL against murine B16F10 melanoma tumor-bearing mice revealed that FDL inhibited tumor growth more efficiently than the DL. Taken together, the results demonstrated the significant potential of the folate-conjugated nanoliposomal system for drug delivery to tumors.     

Influence of Nutrient Availability and Quorum Sensing on the Formation of Metabolically Inactive Microcolonies Within Structurally Heterogeneous Bacterial Biofilms: An Individual-Based 3D Cellular Automata Model

The resistance of bacterial biofilms to antibiotic treatment has been attributed to the emergence of structurally heterogeneous microenvironments containing metabolically inactive cell populations. In this study, we use a three-dimensional individual-based cellular automata model to investigate the influence of nutrient availability and quorum sensing on microbial heterogeneity in growing biofilms. Mature biofilms exhibited at least three structurally distinct strata: a high-volume, homogeneous region sandwiched between two compact sections of high heterogeneity. Cell death occurred preferentially in layers in close proximity to the substratum, resulting in increased heterogeneity in this section of the biofilm; the thickness and heterogeneity of this lowermost layer increased with time, ultimately leading to sloughing. The model predicted the formation of metabolically dormant cellular microniches embedded within faster-growing cell clusters. Biofilms utilizing quorum sensing were more heterogeneous compared to their non-quorum sensing counterparts, and resisted sloughing, featuring a cell-devoid layer of EPS atop the substratum upon which the remainder of the biofilm developed. Overall, our study provides a computational framework to analyze metabolic diversity and heterogeneity of biofilm-associated microorganisms and may pave the way toward gaining further insights into the biophysical mechanisms of antibiotic resistance.     

Investigating microscale patchiness of motile microbes under turbulence in a simulated convective mixed layer

Microbes play a primary role in aquatic ecosystems and biogeochemical cycles. Spatial patchiness is a critical factor underlying these activities, influencing biological productivity, nutrient cycling and dynamics across trophic levels. Incorporating spatial dynamics into microbial models is a long-standing challenge, particularly where small-scale turbulence is involved. Here, we combine a fully 3D direct numerical simulation of convective mixed layer turbulence, with an individual-based microbial model to test the key hypothesis that the coupling of gyrotactic motility and turbulence drives intense microscale patchiness. The fluid model simulates turbulent convection caused by heat loss through the fluid surface, for example during the night, during autumnal or winter cooling or during a cold-air outbreak. We find that under such conditions, turbulence-driven patchiness is depth-structured and requires high motility: Near the fluid surface, intense convective turbulence overpowers motility, homogenising motile and non-motile microbes approximately equally. At greater depth, in conditions analogous to a thermocline, highly motile microbes can be over twice as patch-concentrated as non-motile microbes, and can substantially amplify their swimming velocity by efficiently exploiting fast-moving packets of fluid. Our results substantiate the predictions of earlier studies, and demonstrate that turbulence-driven patchiness is not a ubiquitous consequence of motility but rather a delicate balance of motility and turbulent intensity.     

Studies on inhibitory activities of antibodies against phytopathogenic fungi: an immunological approach

The major problem in agriculture is that of the fungal pathogens. In this era, where biological control is at focus, and is the centre of crop protection as well as environmental protection, the synthesis of new bio bodies is of utmost need. Fungicides available in the market, though of potential, are pathogen specific and highly pollutive. An attempt was made to raise polyclonal antibodies against Aspergillus niger. Following the particular standardised immunisation schedule, regular injections and periodic tapping were carried out. The IgG purified was used to check cross-reactivity with different crop fungi like Fusarium solani, Fusarium oxysporum f. sp. cicer (FOC), Rhizoctonia bataticola, Botryodiplodia theobromae, Curvularia sp., Alternaria porri and also with Aspergillus niger by two different methods. Liquid test media and the radial growth inhibition test performed in solid media were used to check the inhibition of fungi and cross-reactivity. The results were subjected to analysis of variance (ANOVA) by using Tukey's test at the significance level of p < 0.05. The antibodies were active against all the fungi for more than 15 days except for A. niger in which from the seventh day onwards spore germination was observed. The probable role of antibodies to detect the common antigenic molecule that may be present in all the tested fungi and their role in inhibiting these fungi is discussed.     

Effect of oleanane triterpenoids from Terminalia arjuna — a cardioprotective drug on the process of respiratory oxyburst

The oleanane triterpenes arjunic acid, arjungenin and their glucosides, arjunetin and arjunglucoside II, were isolated from the bark of Terminalia arjuna. Arjungenin and its glucoside exhibited a moderate free radical scavenging activity while all the compounds showed no effect on the superoxide release from PMN cells. Further arjungenin also exhibited greater inhibitory action on the hypochlorous acid production from human neutrophils.     

Mixotrophic cultivation of microalgae to enhance the quality of lipid for biodiesel application: effects of scale of cultivation and light spectrum on reduction of α-linolenic acid

Bioprocess and Biosystems Engineering - The research on microalgal biodiesel is focused not only on getting the highest lipid productivity but also desired quality of lipid. The experiments were...