Natural Variations in Comet-Aggregate Meteoroid Compositions

Author(s):  
Frans J. M. Rietmeijer
Keyword(s):  
2021 ◽  
Author(s):  
Jilong Li ◽  
Yawen Zeng ◽  
Yinghua Pan ◽  
Lei Zhou ◽  
Zhanying Zhang ◽  
...  

2021 ◽  
Vol 22 (10) ◽  
pp. 5069
Author(s):  
Naoto Sano ◽  
Annie Marion-Poll

Abscisic acid (ABA) is a key hormone that promotes dormancy during seed development on the mother plant and after seed dispersal participates in the control of dormancy release and germination in response to environmental signals. The modulation of ABA endogenous levels is largely achieved by fine-tuning, in the different seed tissues, hormone synthesis by cleavage of carotenoid precursors and inactivation by 8′-hydroxylation. In this review, we provide an overview of the current knowledge on ABA metabolism in developing and germinating seeds; notably, how environmental signals such as light, temperature and nitrate control seed dormancy through the adjustment of hormone levels. A number of regulatory factors have been recently identified which functional relationships with major transcription factors, such as ABA INSENSITIVE3 (ABI3), ABI4 and ABI5, have an essential role in the control of seed ABA levels. The increasing importance of epigenetic mechanisms in the regulation of ABA metabolism gene expression is also described. In the last section, we give an overview of natural variations of ABA metabolism genes and their effects on seed germination, which could be useful both in future studies to better understand the regulation of ABA metabolism and to identify candidates as breeding materials for improving germination properties.


2021 ◽  
Author(s):  
Tongbing Su ◽  
Weihong Wang ◽  
Peirong Li ◽  
Xiaoyun Xin ◽  
Yangjun Yu ◽  
...  

2020 ◽  
pp. 1-32
Author(s):  
John D. Bonvillian ◽  
Nicole Kissane Lee ◽  
Tracy T. Dooley ◽  
Filip T. Loncke

Chapter 10 provides an introduction to the organization of the Simplified Sign System lexicon and its supporting materials. This chapter explains the various conventions used in the sign illustrations so that learners can accurately interpret the drawings, including the numbering of initial, intermediate, and final positions; the size, shape, and repetition of arrows, quotes, and other marks that depict the sign’s movement; and the provision of facial expressions on signs that convey emotional information. Drawings and expanded written descriptions of the handshapes used in the Simplified Sign System are provided, along with information on how prevalent each handshape is in the system and a sampling of the particular meanings that a handshape can convey within the system. Drawings and written descriptions of the various palm orientations and finger/knuckle orientations used in the system are provided as well so that family members, educators, and other professionals will be able to accurately interpret each sign’s written description. Also discussed in this chapter are the memory aids provided with each sign, natural variations in sign formation and production that are to be expected, as well as what to do if a sign learner has functional use of only one hand and arm.


2021 ◽  
Author(s):  
Bin Tang ◽  
Meijie Luo ◽  
Yunxia Zhang ◽  
Huanle Guo ◽  
Jingna Li ◽  
...  

SummaryCadmium (Cd) accumulation in maize grains is detrimental to human health. Developing maize varieties with low-Cd contents via marker-assisted selection is important for ensuring the production of maize grains safe for consumption. However, the key gene controlling maize grain Cd accumulation has not been cloned. In this study, we identified two major loci for maize grain Cd accumulation (qCd1 and qCd2) on chromosome 2 during a genome-wide association study (GWAS). The qCd1 locus was analyzed by bulked segregant RNA-seq and fine mapping with a biparental segregating population of Jing724 (low-Cd line) and Mo17 (high-Cd line). The ZmCd1 candidate gene in the qCd1 locus encodes a vacuolar membrane-localized heavy metal P-type ATPase transporter, ZmHMA3, which is orthologous to the tonoplast Cd transporter OsHMA3. Genomic DNA sequence and transcript analyses suggested that a transposon in intron 1 of ZmCd1 is responsible for the abnormal amino acid sequence in Mo17. An EMS mutant analysis and an allelism test confirmed ZmCd1 influences maize grain Cd accumulation. The natural variations in ZmCd1 were used to develop four PCR-based molecular markers, which revealed five ZmCd1 haplotypes in the GWAS population. The molecular markers were also used to predict the grain Cd contents in commonly cultivated maize germplasms in China. The predicted Cd contents for 36 inbred lines and 13 hybrids were consistent with the measured Cd contents. Furthermore, several low-Cd elite inbred lines and hybrids were identified, including Jing2416, MC01, Jingnonke728, and Jingke968. Therefore, the molecular markers developed in this study are applicable for molecular breeding and developing maize varieties with low grain Cd contents.


1965 ◽  
Vol 70 (2) ◽  
pp. 479-491 ◽  
Author(s):  
W. R. Shields ◽  
S. S. Goldich ◽  
E. L. Garner ◽  
T. J. Murphy

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