Y.J. Wang

Preparation of coiled hollow-fiber membrane and mass transfer performance in membrane extraction

Abstract Based on the swelling action of organic solvents on hollow-fiber membranes, a new technique of solvent-swelling and dry-shaping for preparing coiled hollow fibers from straight hollow fibers was introduced. The mass transfer performance of these coiled fibers was tested with 30% TBP (in kerosene)–phenol–water as a working system in a membrane extraction process, and compared with the results obtained from the straight fibers. After long time test, it was proved that the coiled fibers were stable when they contacted with the organic solvent in the membrane extraction process. As to the mass transfer performance, it was found that the presence of vortices in the coiled fibers provided better mass transfer performance than the straight fibers. The improvement factor was in the range of 2–4. With an increase of the phase velocity inside the tube, the mass transfer coefficient and energy input in the coiled fibers grew up much more quickly than that in the straight fibers. An empirical correlation for predicting the mass transfer coefficients and an equation for pressure drop in the coiled fibers were suggested.

Autophagy functions as an antiviral mechanism against geminiviruses in plants

Autophagy is an evolutionarily conserved process that recycles damaged or unwanted cellular components, and has been linked to plant immunity. However, how autophagy contributes to plant immunity is unknown. Here we reported that the plant autophagic machinery targets the virulence factor βC1 of Cotton leaf curl Multan virus (CLCuMuV) for degradation through its interaction with the key autophagy protein ATG8. A V32A mutation in βC1 abolished its interaction with NbATG8f, and virus carrying βC1V32A showed increased symptoms and viral DNA accumulation in plants. Furthermore, silencing of autophagy-related genes ATG5 and ATG7 reduced plant resistance to the DNA viruses CLCuMuV, Tomato yellow leaf curl virus, and Tomato yellow leaf curl China virus, whereas activating autophagy by silencing GAPC genes enhanced plant resistance to viral infection. Thus, autophagy represents a novel anti-pathogenic mechanism that plays an important role in antiviral immunity in plants. DOI: http://dx.doi.org/10.7554/eLife.23897.001

CLCuMuB βC1 Subverts Ubiquitination by Interacting with NbSKP1s to Enhance Geminivirus Infection in Nicotiana benthamiana

Viruses interfere with and usurp host machinery and circumvent defense responses to create a suitable cellular environment for successful infection. This is usually achieved through interactions between viral proteins and host factors. Geminiviruses are a group of plant-infecting DNA viruses, of which some contain a betasatellite, known as DNAβ. Here, we report that Cotton leaf curl Multan virus (CLCuMuV) uses its sole satellite-encoded protein βC1 to regulate the plant ubiquitination pathway for effective infection. We found that CLCuMu betasatellite (CLCuMuB) βC1 interacts with NbSKP1, and interrupts the interaction of NbSKP1s with NbCUL1. Silencing of either NbSKP1s or NbCUL1 enhances the accumulation of CLCuMuV genomic DNA and results in severe disease symptoms in plants. βC1 impairs the integrity of SCFCOI1 and the stabilization of GAI, a substrate of the SCFSYL1 to hinder responses to jasmonates (JA) and gibberellins (GA). Moreover, JA treatment reduces viral accumulation and symptoms. These results suggest that CLCuMuB βC1 inhibits the ubiquitination function of SCF E3 ligases through interacting with NbSKP1s to enhance CLCuMuV infection and symptom induction in plants.

Mass transfer characteristics of cadmium(II) extraction in hollow fiber modules

Using di-(2-ethylhexyl) phosphoric acid (D2EPHA)/cadmium ion/water as an experimental system, the mass transfer characteristics in hollow fiber modules (HFMs) were studied by Voronoi tessellation method based on normal distribution function, in which the standard variance could be correlative with the packing irregularity of fibers. The theoretical results showed that not only the packing density but also the packing irregularity significantly influenced the mass transfer characteristics in HFMs. For modules with the same densities, the different packing irregularity led to different mass transfer efficiency. The efficiency of modules with moderate packing density was the lowest because of their most serious packing irregularity. Compared with the exponent distribution function used in previous studies, the normal distribution function can determine the effect of packing irregularity on mass transfer performance accurately. The experimental results also showed a high extraction efficiency of cadmium ion from the wastewater by HFMs.

Cotton Leaf Curl Multan virus C4 protein suppresses both transcriptional and post-transcriptional gene silencing by interacting with SAM synthetase

Gene silencing is a natural antiviral defense mechanism in plants. For effective infection, plant viruses encode viral silencing suppressors to counter this plant antiviral response. The geminivirus-encoded C4 protein has been identified as a gene silencing suppressor, but the underlying mechanism of action has not been characterized. Here, we report that Cotton Leaf Curl Multan virus (CLCuMuV) C4 protein interacts with S-adenosyl methionine synthetase (SAMS), a core enzyme in the methyl cycle, and inhibits SAMS enzymatic activity. By contrast, an R13A mutation in C4 abolished its capacity to interact with SAMS and to suppress SAMS enzymatic activity. Overexpression of wild-type C4, but not mutant C4R13A, suppresses both transcriptional gene silencing (TGS) and post-transcriptional gene silencing (PTGS). Plants infected with CLCuMuV carrying C4R13A show decreased levels of symptoms and viral DNA accumulation associated with enhanced viral DNA methylation. Furthermore, silencing of NbSAMS2 reduces both TGS and PTGS, but enhanced plant susceptibility to two geminiviruses CLCuMuV and Tomato yellow leaf curl China virus. These data suggest that CLCuMuV C4 suppresses both TGS and PTGS by inhibiting SAMS activity to enhance CLCuMuV infection in plants.