Brassinosteroids promote development of rice pollen grains and seeds by triggering expression of Carbon Starved Anther,a MYB domain protein

Transport of photoassimilates from leaf tissues (source regions) to the sink organs is essential for plant development. Here, we show that a phytohormone, the brassinosteroids (BRs) promotes pollen and seed development in rice by directly promoting expression of Carbon Starved Anther (CSA) which encodes a MYB domain protein. Over‐expression of the BR‐synthesis gene D11 or a BR‐signaling factor OsBZR1 results in higher sugar accumulation in developing anthers and seeds, as well as higher grain yield compared with control non‐transgenic plants. Conversely, knockdown of D11 or OsBZR1 expression causes defective pollen maturation and reduced seed size and weight, with less accumulation of starch in comparison with the control. Mechanically, OsBZR1 directly promotes CSA expression and CSA directly triggers expression of sugar partitioning and metabolic genes during pollen and seed development. These findings provide insight into how BRs enhance plant reproduction and grain yield in an important agricultural crop.     

pp60c-src在血管平滑肌细胞内丝裂原活化蛋白激酶激活中的作用

观察ｐｐ６０ｃ－ｓｒｃ在血管紧张素Ⅱ（ＡｎｇⅡ）诱导血管平滑肌细胞（ＶＳＭＣｓ）内丝裂原活化蛋白激酶（ＭＡＰＫ）激活中的作用,以了解ＡｎｇⅡ促ＶＳＭＣｓ增殖的信号转导过程。将合成的反义ｃ－ｓｒｃ寡脱氧核苷酸（ｏｌｉｇｏｄｅｏｘｙｎｕｃｌｅ－ｏｔｉｄｅｓ,ＯＤＮｓ）以脂质体包裹转染培养的大鼠ＶＳＭＣｓ,用Ｗｅｓｔｅｒｎ印迹测得细胞裂解液中ｐｐ６０ｃ－ｓｒｃ含量明显下降,免疫沉淀方法测得ｐｐ６０ｃ－ｓ     

Landscape genetic structure of Scirpus mariqueter reveals a putatively adaptive differentiation under strong gene flow in estuaries

Estuarine organisms grow in highly heterogeneous habitats, and their genetic differentiation is driven by selective and neutral processes as well as population colonization history. However, the relative importance of the processes that underlie genetic structure is still puzzling. Scirpus mariqueter is a perennial grass almost limited in the Changjiang River estuary and its adjacent Qiantang River estuary. Here, using amplified fragment length polymorphism (AFLP), a moderate‐high level of genetic differentiation among populations (range F_ST: 0.0310–0.3325) was showed despite large ongoing dispersal. FLOCK assigned all individuals to 13 clusters and revealed a complex genetic structure. Some genetic clusters were limited in peripheries compared with very mixing constitution in center populations, suggesting local adaptation was more likely to occur in peripheral populations. 21 candidate outliers under positive selection were detected, and further, the differentiation patterns correlated with geographic distance, salinity difference, and colonization history were analyzed with or without the outliers. Combined results of AMOVA and IBD based on different dataset, it was found that the effects of geographic distance and population colonization history on isolation seemed to be promoted by divergent selection. However, none‐liner IBE pattern indicates the effects of salinity were overwhelmed by spatial distance or other ecological processes in certain areas and also suggests that salinity was not the only selective factor driving population differentiation. These results together indicate that geographic distance, salinity difference, and colonization history co‐contributed in shaping the genetic structure of S. mariqueter and that their relative importance was correlated with spatial scale and environment gradient.     

Inhibitory effect of α-ketoglutaric acid on α-glucosidase: integrating molecular dynamics simulation and inhibition kinetics

Abstract

The inhibition of α-glucosidase is used as a key clinical approach to treat type 2 diabetes mellitus and thus, we assessed the inhibitory effect of α-ketoglutaric acid (AKG) on α-glucosidase with both an enzyme kinetic assay and computational simulations. AKG bound to the active site and interacted with several key residues, including ASP68, PHE157, PHE177, PHE311, ARG312, TYR313, ASN412, ILE434 and ARG439, as detected by protein–ligand docking and molecular dynamics simulations. Subsequently, we confirmed the action of AKG on α-glucosidase as mixed-type inhibition with reversible and rapid binding. The relevant kinetic parameter IC₅₀ was measured (IC₅₀ = 1.738?±?0.041?mM), and the dissociation constant was determined (K_{i Slope} = 0.46?±?0.04?mM). Regarding the relationship between structure and activity, a high AKG concentration induced the slight modulation of the shape of the active site, as monitored by hydrophobic exposure. This tertiary conformational change was linked to AKG inhibition and mostly involved regional changes in the active site. Our study provides insight into the functional role of AKG due to its structural property of a hydroxyphenyl ring that interacts with the active site. We suggest that similar hydroxyphenyl ring-containing compounds targeting key residues in the active site might be potential α-glucosidase inhibitors. Abbreviations AKG alpha-ketoglutaric acid

pNPG 4-nitrophenyl-α-d-glucopyranoside

ANS 1-anilinonaphthalene-8-sulfonate

MD molecular dynamics.

Communicated by Ramaswamy H. Sarma     

The cellular response to DNA damage induced by the enediynes C-1027 and neocarzinostatin includes hyperphosphorylation and increased nuclear retention of replication protein a (RPA) and trans inhibition of DNA replication

This study examined the cellular response to DNA damage induced by antitumor enediynes C-1027 and neocarzinostatin. Treatment of cells with either agent induced hyperphosphorylation of RPA32, the middle subunit of replication protein A, and increased nuclear retention of RPA. Nearly all of the RPA32 that was not readily extractable from the nucleus was hyperphosphorylated, compared to < or =50% of the soluble RPA. Enediyne concentrations that induced RPA32 hyperphosphorylation also decreased cell-free SV40 DNA replication competence in extracts of treated cells. This decrease did not result from damage to the DNA template, indicating trans-acting inhibition of DNA replication. Enediyne-induced RPA hyperphosphorylation was unaffected by the replication elongation inhibitor aphidicolin, suggesting that the cellular response to enediyne DNA damage was not dependent on elongation of replicating DNA. Neither recovery of replication competence nor reversal of RPA effects occurred when treated cells were further incubated in the absence of drug. C-1027 and neocarzinostatin doses that caused similar levels of DNA damage resulted in equivalent increases in RPA32 hyperphosphorylation and RPA nuclear retention and decreases in replication activity, suggesting a common response to enediyne-induced DNA damage. By contrast, DNA damage induced by C-1027 was at least 5-fold more cytotoxic than that induced by neocarzinostatin.     

Genetic Diversity and Population Structure Patterns in Chinese Cherry (<Emphasis Type="Italic">Prunus pseudocerasus</Emphasis> Lindl) Landraces

Chinese cherry (Prunus pseudocerasus Lindl.) is an ancient fruit crop with highly economic and ornamental values. It originated in China and the cultivation history can be traced back to 3,000 - 4,000 years ago. Over such a long-term domestication process, a large number of genetic variations have been accumulated in different landraces. However, their utilization for cultivar improvement is limited by the scarcity of information involving genetic diversity and population structure. Here, 17 populations comprised of 140 individuals were collected from four geographic areas: Sichuan Basin (SC), Qinglin Mountain (QL), Yungui Plateau (YG) and North of China (NC), and analyzed using a set of 20 microsatellite markers. In total, 126 polymorphic loci were generated, with 6.3 loci per primer. The global expected heterozygosity (He = 0.63) and Shannon information index (I = 1.23) implied a moderately high level of genetic variation. Two major clusters (cluster 1 and cluster 2) were demonstrated based on population structure analysis, which implied the presence of two potential domestication sites of Chinese cherry landraces. Individuals from SC were assigned to cluster 1 and those from QL, YG and NC were grouped into cluster 2. Samples from QL region contained the most plentiful admixture genetic components, implied the possibility of being one transition region of genetic variation. Moreover, botanical characteristics, such as long lifespan, inbreeding preference as well as vegetative propagation, might lead to a relatively low level but significant genetic divergence among populations. Finally, conservation strategies were proposed to protect these valuable natural germplasm based on these results.