Cooperative microbial interactions drive spatial segregation in porous environments.

The role of microbial interactions and the underlying mechanisms that shape complex biofilm communities are poorly understood. Here we employ a microfluidic chip to represent porous subsurface environments and show that cooperative microbial interactions between free-living and biofilm-forming bacteria trigger active spatial segregation to promote their respective dominance in segregated microhabitats. During initial colonization, free-living and biofilm-forming microbes are segregated from the mixed planktonic inoculum to occupy the ambient fluid and grain surface. Contrary to spatial exclusion through competition, the active spatial segregation is induced by cooperative interactions which improves the fitness of both biofilm and planktonic populations. We further show that free-living Arthrobacter induces the surface colonization by scavenging the biofilm inhibitor, D-amino acids and receives benefits from the public goods secreted by the biofilm-forming strains. Collectively, our results reveal how cooperative microbial interactions may contribute to microbial coexistence in segregated microhabitats and drive subsurface biofilm community succession.

Tumor Targeting and pH-Sensitive Inclusion Complex Based on HP-ß-CD as a Potential Carrier for Paclitaxel: Fabrication, Molecular Docking, and Characterization.

In this study, a tumor-targeting and pH-sensitive inclusion complex based on the host-guest recognition between the chitosan and folic acid grafted HP-ß-CD (FA-CS-CD) and stearic acid modified 2-benzimidazolemethanol (BM-SA) was designed and fabricated for the controlled delivery of paclitaxel (PTX). Through the combination of computational simulations and experiments, the interaction between FA-CS-CD, BM-SA, and PTX was investigated, and the optimized preparation method was obtained. For the optimized PTX-loaded FA-CS-CD/BM-SA inclusion complex, the particle size and zeta potential were 146 nm and +15.4 mV, respectively. In vitro drug release study revealed the pH-triggered drug release behavior of the inclusion complex. Both in vitro and in vivo evaluations demonstrated that the PTX-loaded FA-CS-CD/BM-SA inclusion complex exhibited enhanced antitumor efficiency and minimized systemic toxicity. This system might be a promising carrier for PTX.

AIE-Featured Redox-Sensitive Micelles for Bioimaging and Efficient Anticancer Drug Delivery.

In the present study, an amphiphilic polymer was prepared by conjugating methoxy poly(ethylene glycol) (mPEG) with tetraphenylethene (TPE) via disulfide bonds (Bi(mPEG-S-S)-TPE). The polymer could self-assemble into micelles and solubilize hydrophobic anticancer drugs such as paclitaxel (PTX) in the core. Combining the effect of TPE, mPEG, and disulfide bonds, the Bi(mPEG-S-S)-TPE micelles exhibited excellent AIE feature, reduced protein adsorption, and redox-sensitive drug release behavior. An in vitro intracellular uptake study demonstrated the great imaging ability and efficient internalization of Bi(mPEG-S-S)-TPE micelles. The excellent anticancer effect and low systemic toxicity were further evidenced by the in vivo anticancer experiment. The Bi(mPEG-S-S)-TPE micelles were promising drug carriers for chemotherapy and bioimaging.

Induction of a Cellular DNA Damage Response by Porcine Circovirus Type 2 Facilitates Viral Replication and Mediates Apoptotic Responses.

Cellular DNA damage response (DDR) triggered by infection of DNA viruses mediate cell cycle checkpoint activation, DNA repair, or apoptosis induction. In the present study, infection of porcine circovirus type 2 (PCV2), which serves as a major etiological agent of PCV2-associated diseases (PCVAD), was found to elicit a DNA damage response (DDR) as observed by the phosphorylation of H2AX and RPA32 following infection. The response requires active viral replication, and all the ATM (ataxia telangiectasia-mutated kinase), ATR (ATM- and Rad3-related kinase), and DNA-PK (DNA-dependent protein kinase) are the transducers of the DDR signaling events in the PCV2-infected cells as demonstrated by the phosphorylation of ATM, ATR, and DNA-PK signalings as well as reductions in their activations after treatment with specific kinase inhibitors. Inhibitions of ATM, ATR, and DNA-PK activations block viral replication and prevent apoptotic responses as observed by decreases in cleaved poly-ADP ribose polymerase (PARP) and caspase-3 as well as fragmented DNA following PCV2 infection. These results reveal that PCV2 is able to exploit the cellular DNA damage response machinery for its own efficient replication and for apoptosis induction, further extending our understanding for the molecular mechanism of PCV2 infection.