ZmCYP90D1 regulates maize internode development by modulating brassinosteroid-mediated cell division and growth

Plant height(PH)is associated with lodging resistance and planting density,which is regulated by a complicated gene network.In this study,we identified a spontaneous dwarfing mutation in maize,m30,with decreased internode number and length but increased internode diameter.A candidate gene,ZmCYP90D1,which encodes a member of the cytochrome P450 family,was isolated by map-based cloning.ZmCYP90D1 was constitutively expressed and showed highest expression in basal internodes,and its protein was targeted to the nucleus.A G-to-A substitution was identified to be the causal mutation,which resulted in a truncated protein in m30.Loss of function of ZmCYP90D1 changed expression of hormoneresponsive genes,in particular brassinosteroid(BR)-responsive genes which is mainly involved in cell cycle regulation and cell wall extension and modification in plants.The concentration of typhasterol(TY),a downstream intermediate of ZmCYP90D1 in the BR pathway,was reduced.A haplotype conferring dwarfing without reducing yield was identified.ZmCYP90D1 was inferred to influence plant height and stalk diameter via hormone-mediated cell division and cell growth via the BR pathway.

A peptide chain release factor 2a gene regulates maize kernel development by modulating mitochondrial function

Mitochondrial protein translation that is essential for aerobic energy production includes four essential steps of the mitochondrial ribosome cycle,namely,initiation,elongation,termination of the polypeptide,and ribosome recycling.Translation termination initiates when a stop codon enters the A site of the mitochondrial ribosome where it is recognized by a dedicated peptide release factor(RF).However,RFs and mechanisms involved in translation in plant mitochondria,especially in monocotyledons,remain largely unknown.Here,we identified a crumpled kernel(crk5 allele)mutant,with significantly decreased kernel size,100-kernel weight,and an embryo-lethal phenotype.The Crk5 allele was isolated using map-based cloning and found to encode a mitochondrial localization RF2a.As it is an ortholog of Arabidopsis mitochondrial RF2a,we named the gene ZmmtRF2a.ZmmtRF2a is missing the 5th–7th exons in the crk5 resulting in deletion of domains containing motifs GGQ and SPF that are essential for release activity of RF,mitochondrial ribosome binding,and stop codon recognition.Western blot and qRT-PCR analyses indicate that the crk5 mutation results in abnormal mitochondrion structure and function.Intriguingly,we observed a feedback loop in the crk5 with up-regulated transcript levels detected for several mitochondrial ribosome and mitochondrial-related components,in particular mitochondrial complexes CI,CIV,and a ribosome assembly related PPR.Together,our data support a crucial role for ZmmtRF2a in regulation of mitochondrial structure and function in maize.

遂川江流域雨量站网密度分析研究

确定雨量站网密度是水文规划的重要问题之一,也对开展水资源评价和水文预报至关重要。本文采用抽站法、江西雨量站网密度公式,对遂川江夏溪站流域的雨量站网密度进行研究,揭示了影响面雨量计算精度的主要因素,确定了给定精度要求下区域的合理雨量站布站的密度,为江西省遂川江流域及其他类似地区的雨量站网布设提供参考。

中国少数民族贫困学前儿童的双语词汇发展研究:以维吾尔族和哈萨克族为例

词汇知识是学前儿童语言发展的重要组成部分。儿童的早期双语词汇发展通常能预示他们未来的双语成就。本文对新疆维吾尔自治区三个国家级贫困县(2020年之前)中的维吾尔族和哈萨克族聚居区的135个学前儿童接受性词汇进行了调查。运用国际通行的儿童接受性词汇测试工具PPVT IV的译版对两组儿童分别进行了汉维或汉哈的双语测试。一般线性模型的分析结果显示:两组儿童的本族语词汇得分都高于普通话,而哈萨克族儿童的母语成绩略低于维吾尔族儿童。性别、年龄、母语和居住地对总体儿童的普通话都没有产生显著性影响。但哈萨克儿童的母语知识有显著的年龄主效应,而维吾尔儿童母语则受到居住地的显著影响。两组儿童的词类习得(名词、动词、修饰词)正确率有显著差异,表现在维吾尔儿童的母语和普通话的动词准确率均为最高。本文对确保经济欠发达地区的少数民族学前儿童的双语教育的质量有一定启示意义。

Preparation and Tribological Behavior of BiIn/In_2O_3 Composite Dendritic Nanocrystals

Biln/In2O3 composite dendritic nanocrystals were prepared by dispersing alloy droplets in paraffin oil. The morphology and structure of the alloy nanocrystals were characterized by transmission electron microscopy （TEM）, X-ray photoelectron spectra （XPS）, and X-ray powder diffraction （XRD）. The.composite nanocrystals have dendritic morphology, with an average diameter of 10 nm and lengths up to tens and even hundreds of nanometers. Tribological results indicate that the composite nanocrystals as oil additives can improve antiwear ability of base oil, which is better than that of the corresponding monometallic particles. In addition, the lubricating mechanism of the composite nanocrystals was also discussed.

The Effects of Shared Singing Picture Book Instruction on Chinese Immersion Kindergarteners’Spoken Vocabulary Recall and Retention

The present study investigates the effects of shared singing of a picture book on the Chinese vocabulary recall and retention of young bilingual learners in Chinese immersion programs using an experimental study design.One hundred and six immersion kindergarteners from three different school districts in the U.S.Midwest were assigned to the experimental group(n=53)and the control group(n=53)at the class level.The experimental group listened to a song-based storybook(also known as a story song)and shared in singing it,while the control group heard the same story,read aloud and shared in reading it.The pre-test was administered to determine the participants’vocabulary level before the study.Immediate and delayed post-tests were used to assess their immediate recall and delayed retention of vocabulary targeted in the shared reading/singing.Independent t-test and one-way ANOVA analysis were employed to examine differences between the two groups in vocabulary recall and retention.The results showed that the experimental group achieved greater improvement in their vocabulary than the control group.This finding suggests that shared singing can be a useful pedagogical tool for spoken vocabulary acquisition and retention in picture books.

A Multilevel Analysis of Asian Immigrant Children’s Reading Achievement in the Early Years:Evidence from the ECLS-K Data

This study investigates 1.5 generation1 Asian immigrant children’s(n=264)early literacy achievement patterns,treating them as a heterogeneous group.Specifically,the within-group variances in reading achievement from kindergarten to third grade are examined,drawing on four waves of data from the ECLS-K class of 1998-1999.Our analysis shows that ethnicity plays a role in shaping the children’s initial reading readiness and later growth,but the effects of languages spoken at home are not significant.Our analysis also demonstrates a persistent achievement gap between low-and high-socioeconomic status(SES)Asian groups.However,gender difference in terms of children’s reading development is not found to be significant.There is also no interaction between SES and the other factors such as gender,ethnicity and language backgrounds.