scholarly journals Derived alleles of two axis proteins affect meiotic traits in autotetraploid Arabidopsis arenosa

2020 ◽  
Vol 117 (16) ◽  
pp. 8980-8988 ◽  
Author(s):  
Chris Morgan ◽  
Huakun Zhang ◽  
Clare E. Henry ◽  
F. Chris H. Franklin ◽  
Kirsten Bomblies
Keyword(s):  
Meiotic Chromosome ◽  
Interacting Proteins ◽  
Polyploid Evolution ◽  
Sister Chromatids ◽  
Term Evolution ◽  
Chromosome Associations ◽  
Arabidopsis Arenosa ◽  
Axis Length ◽  
Eukaryotic Genomes

Polyploidy, which results from whole genome duplication (WGD), has shaped the long-term evolution of eukaryotic genomes in all kingdoms. Polyploidy is also implicated in adaptation, domestication, and speciation. Yet when WGD newly occurs, the resulting neopolyploids face numerous challenges. A particularly pernicious problem is the segregation of multiple chromosome copies in meiosis. Evolution can overcome this challenge, likely through modification of chromosome pairing and recombination to prevent deleterious multivalent chromosome associations, but the molecular basis of this remains mysterious. We study mechanisms underlying evolutionary stabilization of polyploid meiosis using Arabidopsis arenosa, a relative of A. thaliana with natural diploid and meiotically stable autotetraploid populations. Here we investigate the effects of ancestral (diploid) versus derived (tetraploid) alleles of two genes, ASY1 and ASY3, that were among several meiosis genes under selection in the tetraploid lineage. These genes encode interacting proteins critical for formation of meiotic chromosome axes, long linear multiprotein structures that form along sister chromatids in meiosis and are essential for recombination, chromosome segregation, and fertility. We show that derived alleles of both genes are associated with changes in meiosis, including reduced formation of multichromosome associations, reduced axis length, and a tendency to more rod-shaped bivalents in metaphase I. Thus, we conclude that ASY1 and ASY3 are components of a larger multigenic solution to polyploid meiosis in which individual genes have subtle effects. Our results are relevant for understanding polyploid evolution and more generally for understanding how meiotic traits can evolve when faced with challenges.

scholarly journals Universal constraints on protein evolution in the long-term evolution experiment with Escherichia coli

2020 ◽  
Author(s):  
Rohan Maddamsetti
Keyword(s):  
Protein Evolution ◽  
Long Term Evolution ◽  
Protein Abundance ◽  
Interacting Proteins ◽  
Protein Thermostability ◽  
Protein Protein Interaction ◽  
Term Evolution ◽  
Evolution Experiment ◽  
Positive Correlations

AbstractAlthough it is well known that highly expressed and highly interacting proteins evolve slowly across the tree of life, there is little consensus for why this is true. Here, I report that highly abundant and highly interacting proteins evolve slowly in the hypermutator populations of Lenski’s long-term evolution experiment with E. coli (LTEE). Specifically, the density of observed mutations per gene, as measured in metagenomic time series covering 60,000 generations of the LTEE, strongly anti-correlates with mRNA abundance, protein abundance, and degree of protein-protein interaction. Weaker positive correlations between protein thermostability and mutation density are observed in the hypermutator populations, counterbalanced by negative correlations between protein thermostability and mRNA and protein abundance. These results show that universal constraints on protein evolution are visible in data spanning three decades of experimental evolution. Therefore, it should be possible to design experiments to answer why highly expressed and highly interacting proteins evolve slowly.

Link-Level Simulator for Wireless local Area Network

2018 ◽  
Vol 6 (7) ◽  
pp. 314
Author(s):  
Chaithra. H. U ◽  
Vani H.R
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area Networks ◽  
Local Area ◽  
Long Term Evolution ◽  
Wireless Local Area Networks ◽  
Area Network ◽  
Network Simulator ◽  
Term Evolution

Now a days in Wireless Local Area Networks (WLANs) used in different fields because its well-suited simulator and higher flexibility. The concept of WLAN  with  advanced 5th Generation technologies, related to a Internet-of-Thing (IOT). In this project, representing the Network Simulator (NS-2) used linked-level simulators for Wireless Local Area Networks and still utilized IEEE 802.11g/n/ac with advanced IEEE 802.11ah/af technology. Realization of the whole Wireless Local Area Networking linked-level simulators inspired by the recognized Vienna Long Term Evolution- simulators. As a outcome, this is achieved to link together that simulator to detailed performances of Wireless Local Area Networking with Long Term Evolution, operated in the similar RF bands. From the advanced 5th Generation support cellular networking, such explore is main because different coexistences scenario can arise linking wireless communicating system to the ISM and UHF bands.

Simulación de cobertura del modelo de radio propagación 3GPP para un entorno urbano en una red 4G – LTE

2013 ◽  
Vol 8 (15) ◽  
pp. 33-40
Author(s):  
Javier Enrique Arévalo Peña
Keyword(s):  
Long Term Evolution ◽  
Term Evolution ◽  
Nuevas Tecnologías ◽  
4G Lte ◽  
3Rd Generation Partnership Project

En la planeación de las próximas generaciones de redes inalámbricas es importante contar con estudios de radio propagación que permitan establecer diseños adecuados para ofrecer los servicios proyectados por las nuevas tecnologías a los usuarios móviles. En este artículo se presentan aspectos relacionados con el comportamiento de cobertura de radio propagación del modelo propuesto por el 3GPP (3rd Generation Partnership Project) para un entorno urbano en una red LTE (Long Term Evolution) empleando sistemas de antenas convencionales y sistemas de antena adaptativas (AAS). Para ello se utiliza la herramienta de software ICS Designer y se establece como escenario los alrededores la Fundación Universidad Autónoma de Colombia ubicada en el centro urbano de la ciudad de Bogotá D. C.

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