The environment,especially the minimum temperature,affects summer maize grain yield by regulating ear differentiation and grain development

Ear differentiation,grain development and their interaction with factors in the growing environment,such as temperature,solar radiation and precipitation,greatly influence grain number and grain weight,and ultimately affect summer maize production.In this study,field experiments involving different sowing dates were conducted over three years to evaluate the effects of temperature factors,average solar radiation and total precipitation on the growth process,ear differentiation,fertilization characteristics,grain filling and yield of summer maize varieties with different growth durations.Four hybrids were evaluated in Huang-Huai-Hai Plain(HHHP),China from 2018 to 2020 with five different sowing dates.The results showed that the grain yield formation of summer maize was strongly impacted by the environment from the silking(R1)to milking(R3)stage.Average minimum temperature(AT_(min))was the key environmental factor that determined yield.Reductions in the length of the growing season(r=–0.556,P<0.01)and the total floret number on ear(R^(2)=0.200,P<0.001)were found when AT_(min) was elevated from the emerging(VE)to R1 stage.Both grain-filling rate(R^(2)=0.520,P<0.001)and the floret abortion rate on ear(R^(2)=0.437,P<0.001)showed quadratic relationships with AT_(min) from the R1 to physiological maturity(R6)stage,while the number of days after the R1 stage(r=–0.756,P<0.01)was negatively correlated with AT_(min).An increase in AT_(min) was beneficial for the promotion of yield when it did not exceeded a certain level(above 23°C during the R1–R3 stage and 20–21°C during the R1-R6 stage).Enhanced solar radiation and precipitation during R1–R6 increased the grain-filling rate(R^(2)=0.562,P<0.001 and R^(2)=0.229,P<0.05,respectively).Compared with short-season hybrids,full-season hybrids showed much greater suitability for a critical environment.The coordinated regulation of AT_(min),ear differentiation and grain development at the pre-and post-silking stages improved maize yield by increasing total floret number and grain-filling rate,and by reducing the floret abortion rate on ear.

ON THE DIFFERENTIATION OF THE ECONOMIC DEVELOPMENT OF CHINA’S NORTH,CENTRAL & SOUTH COASTAL REGIONS

Ⅰ. An analysis of the development trend of the economy in the north,middle aud south coastal regions or China since China began to implementreform and open

Identification of Differentially Expressed Genes Associated with Cotton Fiber Development in a Chromosomal Substitution Line(CS-B22sh)

One of the impediments in the genetic improvement of cotton fiber is the paucity of information about genes associated with fiber development.Availability of chromosome arm substitution line CS-

DIAGONAL POINT BY POINT SURFACE DEVELOPMENT METHOD BASED ON NURBS SURFACE FOR BLANK SHAPE ESTIMATION OFCOVER PANEL

According to the characteristics of a complex cover panel, its geometry shape is described by the NURBS surface with great description capability. With the reference to the surface classification determined by Gauss curvature, the proportion of the mid-surface area between before and after being developed is derived from the displacement variation of the mid-surface in the normal vector direction of the sheet metal during the sheet metal forming process. Hereby, based on the curve development theory in differential geometry, a novel diagonal point by point surface development method is put forward to estimate a complex cover panel＇s blank contour efficiently. By comparing the sample＇s development result of diagonal point by point surface development method with that of available one-step method, the validity of the proposed surface development method is verified.

Stem cell differentiation and human liver disease

Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approach has the potential to improve our understanding of human biology and treating disease.In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases.In recent years,eff icient hepatic differentiation from human stem cells has been achieved by several research groups including our own.In this review we provide an overview of the f ield and discuss the future potential and limitations of stem cell technology.

Organic matter pores in the chang 7 lacustrine shales from the Ordos Basin and its effect on reflectance measurement

To quantify the pore characteristics of various macerals in Chang 7 lacustrine shales,macerals were effectively identified according to their optical and morphological characteristics,and the nanoscale pore structure of macerals was observed by scanning electron microscope.Meanwhile,the reflectances of different positions in the same pieces of vitrinite or solid bitumen with heterogeneous pores development were measured.The results showed that the average contents of sapropelinite,liptinite,vitrinite,inertinite and solid bitumen are 42.7%,8.7%,13.6%,13.8% and 21.2%,respectively,which suggests that the source of the organic matter of the Chang 7 shales is a mixed source input.The organic pores of Chang 7 shales are enriched,and the pore shapes are mostly round or elliptical.The pore size of organic pores has a wide distribution,mainly concentrate in the range of 100-400 nm,and the average plane porosity of organic pores is 10.13%.The size order of the organic pores in various macerals is:solid bitumen<bituminite<alginite<vitrinite<fusinite<liptinite.The abundance order of organic matter pores of each maceral is as follows:alginite>fusinite>bituminite>solid bitumen>vitrinite>liptinite.OM pores are mainly contributed by bituminite,solid bitumen and fusinite.The plane porosity of bituminite increases with maturity.In the process of thermal evolution,the plane porosity of fusinite is distributed in the two ranges of 20%-28% and 1%-7%.The former is mainly the primary pores of the fusinite itself,and the latter is the secondary pores formed in the thermal evolution.As for the organic pores of other macerals,no obvious thermal evolution law was found.Meanwhile,the surface imperfections of vitrinite or solid bitumen is enhanced by the enrichment of organic pores(an increase in pore size or pore number),which may result in the underestimation of their reflectances.

RNA-Seq transcriptome analysis of porcine cloned and in vitro fertilized blastocysts

Somatic nuclear transfer technology has become increasingly promising in biomedicine and agriculture.Whereas the approach remains inefficient and underlying mechanisms remain ambiguous.Although cloned embryos have similar in vitro developmental capacity as in vitro fertilized（IVF） embryos before implantation,they appeared to have much lower full-term developmental efficiency in pig and cattle,and thus it would be reasonable to postulate that profound distinction at the molecular level should exist between them.Herein,RNA sequencing technique was used to screen differentially expressed genes in cloned and IVF blastocysts,and in total 628 differentially expressed transcripts were obtained,among which,280 transcripts are up-regulated and 348 transcripts are down-regulated in cloned blastocysts.Moreover,one statistically significant pathway associated with endoplasmic reticulum（ER） protein processing was enriched,and some ER-stress markers such as ATF4,ATF6,PDIA3,HSPA1 B,HSP40 and HSP90 between cloned and IVF blastocysts were suggested.Additionally,some developmentally important genes such as lipid metabolism related genes（MGLL,DDHD2 and FADS2） and epigenetic modification genes（DNMT1,KDM5 C and MBD3L5） were found differentially expressed between cloned and IVF embryos.

Molecular regulation of development and differentiation in Streptomyces

Development and differentiation is an important and leading research field in modern biology. Streptomyces has a complicated life cycle of morphological differentiation including the spore germination, aerial mycelium and spore formation. Each developmental stage has a distinguished morphological feature which greatly facilitates the identification of developmental mutants, the complementary cloning and the spatial and temporal expression of the genes involved in differentiation. This characteristic of Streptomyces is comparatively superior to other pro-karyotic bacteria such as Escherichia coli, Bacillus sub-tilis and Myxococcus xanthus. Moreover, Streptomyces also possesses a complicated physiological differentiation in which it produces a wide variety of secondary metabolites (more than half of the 12 000 or so known antibiotics), including many important antibiotics used in medi-

Differential requirement of BAK1 C-terminal tail in development and immunity

Summary BRI1-ASSOCIATED RECEPTOR KINASE 1 （BAK1） plays critical roles in plant developmental and immune signaling pathways. BAKI and a large number of leucine-rich repeat receptor-like kinases （LRR-RLKs） harbor a mysterious carboxyl-terminal tail （CT） beyond their kinase domain. In this study we analyzed the biological significance of this CT region using a unique bak~ mutant allele which causes deletion of the CT region. We showed that BAKt CT promotes its kinase activity and is required for pathogen-associated molec- ular pattern （PAMP）-triggered immunity, but it is dispensable for brassinosteroid responses and BAK1/ BKKl-inhibited cell death signaling. Therefore the BAK1 C-terminal tail is differentially required for its functions in development and immunity.