Memory shapes microbial populations

Correct decision making is fundamental for all living organisms to thrive under environmental changes. The patterns of environmental variation and the quality of available information define the most favourable strategy among multiple options, from randomly adopting a phenotypic state to sensing and reacting to environmental cues. Cellular memory—the ability to track and condition the time to switch to a different phenotypic state—can help withstand environmental fluctuations. How does memory manifest itself in unicellular organisms? We describe the population-wide consequences of phenotypic memory in microbes through a combination of deterministic modelling and stochastic simulations. Moving beyond binary switching models, our work highlights the need to consider a broader range of switching behaviours when describing microbial adaptive strategies. We show that memory in individual cells generates patterns at the population level coherent with overshoots and non-exponential lag times distributions experimentally observed in phenotypically heterogeneous populations. We emphasise the implications of our work in understanding antibiotic tolerance and, in general, bacterial survival under fluctuating environments.     

Stable suppression of myostatin gene expression in goat fetal fibroblast cells by lentiviral vector‐mediated RNAi

Myostatin (MSTN) is a secreted growth factor that negatively regulates skeletal muscle mass, and therefore, strategies to block myostatin‐signaling pathway have been extensively pursued to increase the muscle mass in livestock. Here, we report a lentiviral vector‐based delivery of shRNA to disrupt myostatin expression into goat fetal fibroblasts (GFFs) that were commonly used as karyoplast donors in somatic‐cell nuclear transfer (SCNT) studies. Sh‐RNA positive cells were screened by puromycin selection. Using real‐time polymerase chain reaction (PCR), we demonstrated efficient knockdown of endogenous myostatin mRNA with 64% down‐regulation in sh2 shRNA‐treated GFF cells compared to GFF cells treated by control lentivirus without shRNA. Moreover, we have also demonstrated both the induction of interferon response and the expression of genes regulating myogenesis in GFF cells. The results indicate that myostatin‐targeting siRNA produced endogenously could efficiently down‐regulate myostatin expression. Therefore, targeted knockdown of the MSTN gene using lentivirus‐mediated shRNA transgenics would facilitate customized cell engineering, allowing potential use in the establishment of stable cell lines to produce genetically engineered animals. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 31:452–459, 2015     

Essential roles of mitochondrial and heme function in lung cancer bioenergetics and tumorigenesis

Contrary to Warburg’s hypothesis, mitochondrial oxidative phosphorylation (OXPHOS) contributes significantly to fueling cancer cells. Several recent studies have demonstrated that radiotherapy-resistant and chemotherapy-resistant cancer cells depend on OXPHOS for survival and progression. Several cancers exhibit an increased risk in association with heme intake. Mitochondria are widely known to carry out oxidative phosphorylation. In addition, mitochondria are also involved in heme synthesis. Heme serves as a prosthetic group for several proteins that constitute the complexes of mitochondrial electron transport chain. Therefore, heme plays a pivotal role in OXPHOS and oxygen consumption. Further, lung cancer cells exhibit heme accumulation and require heme for proliferation and invasion in vitro. Abnormalities in mitochondrial biogenesis and mutations are implicated in cancer. This review delves into mitochondrial OXPHOS and lesser explored area of heme metabolism in lung cancer.     

Smooth muscle cell transplantation improves bladder contractile function in streptozocin-induced diabetic rats

Background aimsDamage to smooth muscle has been the primary cause of dysfunction in diabetic bladders. Major changes in the filling phase of the bladder result in the loss of compliance and incomplete emptying in patients.MethodsCell-based therapies in the lower urinary tract have shown promising results. We argue that because diabetic bladder dysfunction is primarily a problem arising out of altered smooth muscle cells (SMCs), it would be an interesting approach to introduce healthy SMCs into the bladder wall.ResultsFurthering this hypothesis, in this experiment, we were successful in introducing syngeneic, healthy SMCs into diabetic bladders. We attempted a method wherein bladder function can be improved in streptozocin-induced diabetes mellitus. Ex vivo–cultured healthy SMCs were introduced into the diabetic bladders of syngeneic Sprague-Dawley rats during the hypercontractile phase after induction of diabetes. Cystometry, metabolic cage evaluation, organ bath studies and histological analyses were performed on the healthy control, the diabetic and the diabetic group transplanted with SMCs.ConclusionsDuring the 2-week follow-up period after transplantation, we noticed an increase in contractile response of the bladder correlating to a decrease in residual urine. Cell survival studies revealed a cell survival rate close to 1.5%.     

Bacterial Diversity Dynamics Associated with Different Diets and Different Primer Pairs in the Rumen of Kankrej Cattle

The ruminal microbiome in herbivores plays a dominant role in the digestion of lignocellulose and has potential to improve animal productivity. Kankrej cattle, a popular native breed of the Indian subcontinent, were used to investigate the effect of different dietary treatments on the bacterial diversity in ruminal fractions using different primer pairs. Two groups of four cows were assigned to two primary diets of either dry or green forages. Each group was fed one of three dietary treatments for six weeks each. Dietary treatments were; K1 (50% dry/green roughage: 50% concentrate), K2 (75% dry/green roughage: 25% concentrate) and K3 (100% dry/green roughage). Rumen samples were collected using stomach tube at the end of each dietary period and separated into solid and liquid fractions. The DNA was extracted and amplified for V1–V3, V4–V5 and V6–V8 hypervariable regions using P1, P2 and P3 primer pairs, sequenced on a 454 Roche platform and analyzed using QIIME. Community compositions and the abundance of most bacterial lineages were driven by interactions between primer pair, dietary treatment and fraction. The most abundant bacterial phyla identified were Bacteroidetes and Firmicutes however, the abundance of these phyla varied between different primer pairs; in each primer pair the abundance was dependent on the dietary treatment and fraction. The abundance of Bacteroidetes in cattle receiving K1 treatment indicate their diverse functional capabilities in the digestion of both carbohydrate and protein while the predominance of Firmicutes in the K2 and K3 treatments signifies their metabolic role in fibre digestion. It is apparent that both liquid and solid fractions had distinct bacterial community patterns (P<0.001) congruent to changes in the dietary treatments. It can be concluded that the P1 primer pair flanking the V1–V3 hyper-variable region provided greater species richness and diversity of bacterial populations in the rumen of Kankrej cattle.     

Theoretical study on <Emphasis Type="Italic">p</Emphasis>-type D-π-A sensitizers with modified π-spacers for dye-sensitized solar cells

Based on a prototype sensitizer W2, we designed triarylamine-based p-type sensitizers W2-1 to W2-7 that contain modified π-spacers (π'), a π-spacer and two anchors. For W2-1 to W2-4, instead of 2,1,3-benzothiadiazole in W2, thieno[3,4-b]-1,4-dioxin, thiophene, thieno[3,4-c][1,2,5]thiadizole, thiazolo[5,4-d]thiazole are π' and thiophene as π-spacer. For W2-5 to W2-8, π' and π are same, with 2,1,3-benzothiadiazole, thieno[3,4-b]-1,4-dioxin, thieno[3,4-c][1,2,5]thiadiazo, thiazolo[5,4-d]thiazole, respectively, as the π'-spacers. Structure optimization, electronic level and absorption characters were calculated with density functional theory (DFT) and time-dependent DFT (TDDFT) at the CAM-B3LYP/6-311G (d,p). The solvent effect was involved using a polarized continuum model in chloroform. The results showed that the highest occupied molecular orbital and the lowest unoccupied molecular orbital guarantee sufficient hole injection (lower than –0.2 eV), and dye regeneration (lower than –0.2 eV). W2-4 has higher light-harvesting efficiency (LHE) (0.994) and larger overlap with the visible light from 400 nm to 600 nm. Finally, the results suggest that the driving force of hole injection, dye regeneration and charge recombination (ΔG_inj, ΔG_reg and ΔG_CR) of W2-4 are the best, with more negative ΔG_inj (–4.33), ΔG_reg (–1.74) and more positive ΔG_CR (1.92). Replacing 2,1,3-benzothiadiazole with thiazolo[5,4-d]thiazole as π'-spacers is a effective way to improve the performance of the dyes. An introduction of thiazolo[5,4-d]thiazole group can improve the absorption ability and hinder charge recombination.

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Graphical abstract Absorption spectra of p-type D-π-A sensitizers with modified π-spacers

     

Synthesis and anticancer activity studies of indolylisoxazoline analogues

A new library of thirteen indolylisoxazolines 6a–m has been synthesized by the treatment of indolylchalcones with hydroxylamine hydrochloride. Evaluation of anticancer activity of indolylisoxazolines 6a–m led to the identification of potent compounds 6c–d, 6i and 6l, with IC₅₀ ranging 2.5–5.0?µM against the tested cancer cell lines. Using a number of complementary techniques such as acridine orange/ethidium bromide staining, PARP1 cleavage and DNA strand breaks assay, we show that the compounds 6c and 6i induce apoptosis in highly aggressive C4-2 cells. Our data further revealed that 6c and 6i inhibited C4-2 cells proliferation without inducing reactive oxygen species (ROS). Finally, we show that compounds 6c and 6i also potently inhibit cell migration, indicating these compounds have the potential to serve as effective anti-cancer agents.