The Flagellar Gene Regulates Biofilm Formation and Mussel Larval Settlement and Metamorphosis.

Biofilms are critical components of most marine systems and provide biochemical cues that can significantly impact overall community composition. Although progress has been made in the bacteria-animal interaction, the molecular basis of modulation of settlement and metamorphosis in most marine animals by bacteria is poorly understood. Here, Pseudoalteromonas marina showing inducing activity on mussel settlement and metamorphosis was chosen as a model to clarify the mechanism that regulates the bacteria-mussel interaction. We constructed a flagellin synthetic protein gene fliP deletion mutant of P. marina and checked whether deficiency of fliP gene will impact inducing activity, motility, and extracellular polymeric substances of biofilms. Furthermore, we examined the effect of flagellar proteins extracted from bacteria on larval settlement and metamorphosis. The deletion of the fliP gene caused the loss of the flagella structure and motility of the ∆fliP strain. Deficiency of the fliP gene promoted the biofilm formation and changed biofilm matrix by reducing ß-polysaccharides and increasing extracellular proteins and finally reduced biofilm-inducing activities. Flagellar protein extract promoted mussel metamorphosis, and ∆fliP biofilms combined with additional flagellar proteins induced similar settlement and metamorphosis rate compared to that of the wild-type strain. These findings provide novel insight on the molecular interactions between bacteria and mussels.

Two-component gas quartz-enhanced photoacoustic spectroscopy sensor based on time-division multiplexing of distributed-feedback laser driver current.

A two-component gas sensor in quartz-enhanced photoacoustic spectroscopy based on time-division multiplexing (TDM) technology of a distributed-feedback (DFB) laser driver current was proposed and experimentally demonstrated. The quartz tuning-fork-based photoacoustic spectroscopy (PAS) cell configuration with two optical collimators and two acoustic microresonators was designed to detect the second-harmonic (${2}f$2f) PAS signal. The two optical collimators guaranteed that the two laser beams would inject the PAS cell conveniently, providing higher power input than a 3 dB optical fiber coupler. Two-component gas sensing was achieved by the TDM of the DFB laser driver current. We used this two-component gas sensing technique to detect acetylene (${{\rm C}_2}{{\rm H}_2}$C2H2) at 1532.83 nm and methane (${{\rm CH}_4}$CH4) at 1653.722 nm. The ${{\rm C}_2}{{\rm H}_2}$C2H2 and ${{\rm CH}_4}$CH4 detection was achieved at a 2.4 s interval. The minimum detection limits of 1 ppmv for ${{\rm C}_2}{{\rm H}_2}$C2H2 and 13.14 ppmv for ${{\rm CH}_4}$CH4 were obtained, and the linear responses reached were 0.99968 and 0.99652 for ${{\rm C}_2}{{\rm H}_2}$C2H2 and ${{\rm CH}_4}$CH4, respectively. Moreover, the continuous monitoring of ${{\rm CH}_4}$CH4 and ${{\rm C}_2}{{\rm H}_2}$C2H2 for 40 min showed a good stability. The TDM technology of the DFB laser driver current would play an important role on the multi-component detection.

Comparison of cardioprotective efficacy resulting from a combination of atorvastatin and ischaemic post-conditioning in diabetic and non-diabetic rats.

The aim of the present study was to investigate whether the combination of acute or chronic atorvastatin treatment with ischaemic post-conditioning (IPost) exerts differential effects within the hearts of diabetic and non-diabetic rats. Diabetic and non-diabetic rats were randomly assigned to one of six groups: (i) a non-conditioned group; (ii) a group subjected to IPost; (iii) acute statin treatment (50 µmol/L atorvastatin during reperfusion) without IPost; (iv) acute statin treatment plus IPost; (v) chronic statin treatment (10 mg/kg atorvastatin per day for 2 weeks) without IPost; and (vi) chronic statin treatment plus IPost. The hearts from rats in each group were subjected to 30 min global ischaemia, followed by 120 min reperfusion. Infarct size, haemodynamics and Akt and endothelial nitric oxide synthase (eNOS) expression were examined. In hearts from diabetic rats, IPost did not limit infarct size or recover contractile dysfunction. Acute atorvastatin treatment with IPost limited infarct size and recovered contractile dysfunction in hearts from both diabetic and non-diabetic rats and further activated Akt and eNOS signalling pathways to enhance these protective effects in hearts from diabetic rats. Chronic statin treatment with IPost neither reduced infarct size nor increased recovery of myocardial dysfunction in hearts from both diabetic and non-diabetic rats; this may be associated with inhibition of Akt and eNOS phosphorylation. The combination of acute atorvastatin treatment with IPost had a greater protective effect within hearts from diabetic rats, but chronic statin treatment with IPost failed to protect against reperfusion injury in hearts from either diabetic or non-diabetic rats. These findings will be important for the design of future clinical investigations.