BackgroundFatty acids synthesized in chloroplast are transported to endoplasmic reticulum (ER) for triacylglycerols (TAGs) resembling. The development of chloroplast also requires lipids trafficking from ER to chloroplast. The membrane contact sites (MCSs) between ER and chloroplast has been demonstrated to be involved for the trafficking of lipids and proteins. Lipids trafficking between ER and chloroplast is often accompanied by lipids interconversion. However, it is rarely known how lipids interconversion happens during their trafficking.Methodology/Principal FindingsWe cloned a lipase gene from Brassica napus L., designated as BnCLIP1. Green fluorescence protein (GFP)-tagged BnCLIP1 was shown to locate at the MCSs between ER and chloroplasts in tobacco leaves. Heterogeneous expression of BnCLIP1 in Saccharomyces cerevisiae (pep4) reduced the total amount of fatty acid. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the truncated BnCLIP1 had a substrate preference for C16:0 lipids in Saccharomyces cerevisiae (pep4). To probe the physiological function of BnCLIP1, two Brassica napus lines with different oil-content were introduced to investigate the transcript patterns of BnCLIP1 during seed development. Intriguingly, the transcript level of BnCLIP1 was found to be immediately up-regulated during the natural seed senescence of both lines; the transcription response of BnCLIP1 in the high oil-content seeds was faster than the lower ones, suggesting a potential role of BnCLIP1 in affecting seed oil synthesis via regulating chloroplast integrity. Further researches showed that chemical disruption of leaf chloroplast also activated the transcription of BnCLIP1.Conclusions/SignificanceThe findings of this study show that BnCLIP1 encodes a lipase, localizes at the MCSs and involves in chloroplast development.

No abstract

The advent of Z-scheme heterojunction makes it possible to improve the CO 2 photoreduction efficiency of photocatalyst significantly. However, the reasonable construction of heterojunction and study of the photocatalytic mechanism remains a major challenge. Here, the Z-scheme heterojunction photocatalyst (BP:La/InVO 4 :La) based on La single atom anchored on black phosphorus for photocatalytic CO 2 reduction with ≈100% CO selectivity is successfully constructed. The CO generation rate of BP:La/5-InVO 4 :La is ≈7.9 and 4.9 times higher than black phosphorus and InVO 4 , respectively. The results of X-ray photoelectron spectroscopy, photoluminescence, and density functional theory indicate that the BP:La/InVO 4 :La belongs to the Z-scheme heterojunction, and the La single atom plays multiple roles such as regulating surface active sites, promoting CO 2 absorption, and increasing O defects, which can further contribute to the improvement of photocatalytic performance. The enhanced selectivity of the Z-scheme heterojunction is further demonstrated by calculating the rate-determining steps and selectivitydetermining steps. The results are expected to provide unique ideas for the rational design of rare earth composite photocatalyst.

Numerical software is widely used in safety-critical systems such as aircrafts, satellites, car engines and many other fields, facilitating dynamics control of such systems in real time. It is therefore absolutely necessary to verify their correctness. Most of these verifications are conducted under ideal mathematical models, but their real executions may not follow the models exactly. Factors that are abstracted away in models such as rounding errors can change behaviors of systems essentially. As a result, guarantees of verified properties despite the present of disturbances are needed. In this paper, we attempt to address this issue of nontermination analysis of numerical software. Nontermination is often an unexpected behaviour of computer programs and may be problematic for applications such as real-time systems with hard deadlines. We propose a method for robust conditional nontermination analysis that can be used to under-approximate the maximal robust nontermination input set for a given program. Here robust nontermination input set is a set from which the program never terminates regardless of the aforementioned disturbances. Finally, several examples are given to illustrate our approach.

In this paper we propose a convex programming based method to compute robust domains of attraction for state-constrained perturbed polynomial continuous-time systems. The robust domain of attraction is a set of states such that every trajectory starting from it will approach the equilibrium while never violating the specified state constraint, irrespective of the actual perturbation. With Kirszbraun's extension theorem for Lipschitz maps, we first characterize the interior of the maximal robust domain of attraction for state-constrained polynomial systems as the strict one sub-level set of the unique viscosity solution to a generalized Zubov's equation. Instead of solving this Zubov's equation based on traditional grid-based numerical methods, we synthesize robust domains of attraction via solving semi-definite programs, which are constructed from the generalized Zubov's equation. A robust domain of attraction could be obtained by solving a single semi-definite program, rendering our method simple to implement. We further show that the existence of solutions to the constructed semi-definite program is guaranteed and there exists a sequence of solutions such that their strict one sub-level sets inner-approximate the interior of the maximal robust domain of attraction in measure under appropriate assumptions. Finally, we evaluate our semi-definite programming based method on three case studies.