Functional characterization of two flavone synthase Ⅱ members in citrus

Polymethoxylated flavones(PMFs),the main form of flavones in citrus,are derived from the flavone branch of the flavonoid biosynthesis pathway.Flavone synthases(FNSs)are enzymes that catalyze the synthesis of flavones from flavanones.However,the FNS in citrus has not been characterized yet.Here,we identified two type II FNSs,designated CitFNSII-1 and CitFNSII-2,based on phylogenetics and transcriptome analysis.Both recombinant CitFNSII-1 and CitFNSII-2 proteins directly converted naringenin,pinocembrin,and liquiritigenin to the corresponding flavones in yeast.In addition,transient overexpression of CitFNSII-1 and CitFNSII-2,respectively,in citrus peel significantly enhanced the accumulation of total PMFs,while virus-induced CitFNSII-1 and CitFNSII-2 genes silencing simultaneously significantly reduced the expression levels of both genes and total PMF content in citrus seedlings.CitFNSII-1 and CitFNSII-2 presented distinct expression patterns in different cultivars as well as different developmental stages.Methyl salicylate(MeSA)treatment reduced the CitFNSII-2 expression as well as the PMFs content in the peel of Citrus sinensis fruit but did not affect the CitFNSII-1 expression.These results indicated that both CitFNSII-1 and CitFNSII-2 participated in the flavone biosynthesis in citrus while the regulatory mechanism governing their expression might be specific.Our findings improved the understanding of the PMFs biosynthesis pathway in citrus and laid the foundation for further investigation on flavone synthesis regulation.

A high-order full-discretization method using Hermite interpolation for periodic time-delayed differential equations

A high-order full-discretization method （FDM） using Hermite interpolation （HFDM） is proposed and implemented for periodic systems with time delay. Both Lagrange interpolation and Hermite interpolation are used to approximate state values and delayed state values in each discretization step. The transition matrix over a single period is determined and used for stability analysis. The proposed method increases the approximation order of the semidiscretization method and the FDM without increasing the computational time. The convergence, precision, and efficiency of the proposed method are investigated using several Mathieu equations and a complex turning model as examples. Comparison shows that the proposed HFDM converges faster and uses less computational time than existing methods.

Naringin,neohesperidin and their corresponding dihydrochalcones as bioactive substances:a symphony of bitter–sweet

Bitter is generally undesirable,although it is an important part of flavor.Bitter substances exhibit diverse health-promoting activities,which is in line with the famous Chinese saying‘a good medicine tastes bitter’.Naringin(NAG)and neohesperidin(NHP),two important flavanones that give bitterness to citrus fruits,show various pharmacological activities.Interestingly,their hydrogenation products,i.e.naringin dihydrochalcone(NDC)and neohesperidin dihydrochalcone(NHDC),undergo a dramatic taste shift from bitter to intensely sweet,which can be 300 and 1000 times sweeter than sucrose,respectively.Such sweeteners not only provide a sweet taste without the burden of increased calorie intake and glycemia,but also may exert multiple bioactivities.This review summarizes common dietary bitter and sweet compounds with sensory scores.Taste conversions induced by structural changes from bitter NAG and NHP to sweet NDC and NHDC are particularly discussed.In addition,the taste-sensing mechanisms,pharmacological characteristics,dietary distribution,synthesis,and food industry applications of these bitter–sweet interchangeable compounds are outlined.In conclusion,the bitter NAG and NHP are promising therapeutic candidates for management of diverse etiologically complex diseases while their corresponding dihydrochalcones NDC and NHDC are promising sweeteners,which might be a blessing for those who need to control sugar intake.

The chemistry,stability and health effects of phenolic compounds in cultivated hawthorn(Crataegus pinnatifida var.major):a review

Cultivated hawthorn(Crataegus pinnatifida var.major),the principal cultivated hawthorn species in China,is rich in phenolic compounds.These phytochemicals are considered essential bioactive ingredients in different organs of cultivated hawthorn,contributing to its health effects.However,there is lack of a comprehensive review that systematically summarizes the chemistry,health effects,and stability of phenolic substances.This review summarizes recent progress in the characterization,classification,and distribution of phenolic compounds in C.pinnatifida var.major,including procyanidins,flavonoids,phenolic acids,lignans,and others.Importantly,the stability of these compounds was found to be influenced by factors such as the hawthorn development process,postharvest storage,postharvest processing,and the gastrointestinal tract environment.Additionally,the health effects of phenolic compounds in cultivated hawthorn and their underlying mechanisms were discussed.This review provides valuable insights into the utilization of hawthorn resources and the development of the hawthorn industry.

Point-defect-driven flattened polar phonon bands in fluorite ferroelectrics

The scale-free ferroelectric polarization of fluorite MO_(2)(M=Hf,Zr)due to flat polar phonon bands are promising for nonvolatile memories.Defects are also widely introduced to improve the emergent ferroelectricity.However,their roles are still not fully understood at the atomic-level.Here,we report a significant effect of point-defect-driven flattening of polar phonon bands with more polar modes and polarization contribution in doped MO_(2).The polar phonon bands in La-doped MO_(2)(M=Hf,Zr)can be significantly flattened,compared with pure ones.However,the lower energy barrier with larger polarization of VO-only doped MO_(2) compared with La-doped cases suggest that VO and local lattice distortion should be balanced for high-performance fluorite ferroelectricity.The work is believed to bridge the relation between point defects and the generally enhanced induced ferroelectricity in fluorite ferroelectrics at the atomic-level and inspire their further property optimization via defect-engineering.

在西准噶尔晚泥盆世陆相地层中发现首例缺棘短胸节甲鱼类

记述了新疆西准噶尔晚泥盆世早法门期月骨鱼科(属于盾皮鱼纲节甲鱼目短胸节甲鱼亚目缺棘短胸节甲鱼超科)一新属——布龙鱼(Bulongosteus gen.nov.).新属发现于朱鲁木特组上部辫状河相砾岩和含砾砂岩中,新属的主要特征是:中颈片呈前缘前凸、后缘前凹的三角形,两侧微内凹;副颈片后缘超过中颈片后缘,发育两条感觉管;眶前片加大以致形成眼眶的前背缘,表面具有较为密集的瘤点;缘片前缘加厚形成眼眶后缘,3条感觉管呈明显"Y"字形;后腹侧片细长.布龙鱼是在新疆首次发现的节甲鱼类,也是缺棘短胸节甲鱼类在陆相沉积中的首次发现,丰富了我国缺棘短胸节甲鱼类的化石记录,扩展了缺棘短胸节甲鱼类的地理分布和生态范围,也表明缺棘短胸节甲鱼类同晚泥盆世众多鱼类一样也是一类广盐性鱼类.