High temperature treatment induced production of unreduced 2n pollen in Camellia oleifera

Unreduced gametes through chromosome doubling play a major role in the process of plant polyploidization.Our previous work confirmed that Camellia oleifera can produce natural 2n pollen,and it is possible to induce the 2n pollen formation by high temperature treatment.This study focused on the optimization of the 2n pollen induction technique and the mechanisms of high temperature-induced2n pollen formation in C.oleifera.We found that the optimal protocol for inducing 2n pollen via high temperature was to perform 45℃with4 h at the prophaseⅠstage of the pollen mother cells(PMCs).Meanwhile,high temperature significantly decreased the yield and fertility of2n pollen.Through the observation of meiosis,abnormal chromosome and cytological behaviour was discovered under high-temperature treatment,and we confirmed that the formation of 2n pollen is caused by abnormal cell plate.Based on weighted gene co-expression network analysis,fifteen hub genes related to cell cycle control were identified.After male flower buds were exposed to heat shock,polygalacturonase gene(CoPGX3)was significantly upregulated.We inferred that high temperature causes the CoPGX3 gene to be overexpressed and that CoPGX3 is redistributed into the cytosol where it degrades cytoplasmic pectin,which leads to an abnormal cell plate.Furthermore,abnormal cytokinesis resulted in the formation of dyads and triads,and PMCs divided to produce 2n pollen.Our findings provide new insights into the mechanism of 2n pollen induced by high temperature in a woody plant and lay a foundation for further ploidy breeding of C.oleifera.

Hexamerin and allergen are required for female reproduction in the American cockroach,Periplaneta americana

Reproduction is of great importance for the continuation of the species.In insects,the fat body is the major tissue for nutrient storage and involved in vitellogenesis,which is essential for female reproduction.Here,2 proteins,hexamerin and allergen,were separated from the fat bodies of adult female American cockroaches(Periplaneta americana)and identified as storage proteins,encoding for 733 amino acids with molecular weight of 87.88 kDa and 686 amino acids with molecular weight of 82.18 kDa,respectively.The encoding genes of these 2 storage proteins are mainly expressed in the fat body.RNA interference-mediated knockdown of Hexamerin and Allergen in the early stage of the first reproductive cycle in females suppressed vitellogenesis and ovarian maturation,indicating that these storage proteins are involved in controlling reproduction.Importantly,the expression of Hexamerin and Allergen was repressed by knockdown of the juvenile hormone(JH)receptor gene Met and the primary response gene Kr-h1,and was induced by methoprene,a JH analog,in both in vivo and in vitro experiments.Altogether,we have determined that hexamerin and allergen are identified as storage proteins and play an important role in promoting female reproduction in the American cockroach.The expression of their encoding genes is induced by JH signaling.Our data reveal a novel mechanism by which hexamerin and allergen are necessary for JH-stimulated female reproduction.

Downstream Competition and Upstream Innovation:Theory and Evidence from China

Competition is the catalyst of corporate innovation,which is the foundation of a country's core competitiveness.From the view of vertical industrial chain,this paper examines how downstream competition affects upstream firms'innovation output.Given innovation helps reduce the production cost of each product,increasing demand of intermediate products caused by downstream competition enhances the marginal revenue of upstream firms'innovation,thus leading to an innovation incentive effect.To identify causality,we utilize China's WTO accession,a quasinatural experiment,to calculate downstream competition combined with import tariff reduction and input-output table,and then run a difference-in-difference regression.Using the data of Annual Survey of Industrial Firms and State Intellectual Property Office,our results find that downstream competition has a significantly positive impact on upstream firms'innovation,and this effect is more pronounced in firms with less industry competition,greater initial innovation capacity and weaker financial constraints.Moreover,the number of firms,the degree of industry competition and the scale of intermediate products in the downstream sector increase,confirming the market size channel.In sum,our findings document that downstream competition can motivate upstream firms to innovate through vertical industrial chain,providing some useful insights for China to build a fair market competition environment and promote innovation-driven growth regime.

Self-filtering illumination source and application in fluorescence imaging

To date,fluorescence imaging systems have all relied on at least one beam splitter(BS)to ensure the separation of excitation light and fluorescence.Here,we reported SiO2=TiO2 multi-layer long pass filter integrated GaN LED.It is considered as the potential source for imaging systems.Experimental results indicate that the GaN LED shows blue emission peaked at 470.3 nm and can be used to excite dye materials.Integrating with a long pass filter(550 nm),the light source can be used to establish a real-time fluorescence detection for dyes that emit light above 550 nm.More interestingly,with this source,a real-time imaging system with signature words written with the dyes,such as‘NJUPT’,can be converted into CCD images.This work may lead to a new strategy for integrating light sources and BS mirrors to build mini and smart fluorescence imaging systems.

Nickel-Catalyzed Regiodivergent Asymmetric Cycloadditions of α,β-Unsaturated Carbonyl Compounds

Regiodivergent asymmetric cycloadditions from the same set of starting materials offer interesting opportunities for rapid construction of optically active cyclic molecules with structural diversity.However,this remains a challenging task due to the difficulty of simultaneously controlling the regio-,diastereo-,and enantioselectivity in the ring formation processes.To address this long-standing problem.

Haplotype-resolved and chromosome-level genome assembly of Colorado potato beetle

As the most important non-cereal food crop,potatoes are a staple food for 1.3 billion people(Stokstad,2019).However,these cultivated potatoes are challenged with multiple biotic stresses(i.e.,pathogens and pests),some of which can evade host resistance,leading to a serious dampening of potato yield.One of these pests is the Colorado potato beetle(hereafter referred to as CPB,Leptinotarsa decemlineata Say).CPB is a member of the order Coleoptera,and originated in the southwestern United States and Mexico(Alyokhin et al.,2008).

Transition metal-free photocatalytic reductive deuteration of ketone derivatives

Deuterium labelling techniques have shown widespread applications in organic synthesis,analytic chemistry,life science and material science.The design of practical deuteration reactions which is environmentally friendly is highly desired for pharmaceutical development and industrial processes while remaining underexplored.We herein report a convenient,transition metal-free strategy for reductive deuteration of ketone derivatives toα-deuterated alcohols by employing a conjugated aryl amine-based organophotocatalyst,a dipropyl disulfide cocatalyst and an inorganic reductant.Upon irradiation with visible light and under an air atmosphere,a variety of diaryl ketones,heteroaryl ketones,cyclic ketones,α-ketoesters,benzil derivatives,aliphatic ketones and drug-like molecules were converted into correspondingα-deuterated aryl alcohols in good to excellent yields and with high deuterium incorporation(up to 99%D-incorporation).Only low toxic side-products,such as sodium salts and carbon dioxide,were generated.Consequently,the synthetic utility of this method is highlighted by the preparation of several D-labeled drug-like molecules,including orphenadrine,carbinoxamine and modafinil.