Cytogenetic relationship within cultivated Brassica analyzed in amphihaploids from the three diploid ancestors

1986 ◽  
Vol 28 (3) ◽  
pp. 323-329 ◽  
Author(s):  
T. Attia ◽  
G. Röbbelen
Keyword(s):  
Chromosome Pairing ◽  
Common Ancestor ◽  
Diploid Species ◽  
Ancestral Genome ◽  
Homologous Pairing ◽  
B Genome ◽  
Close Relationship ◽  
Chromosomal Interchange ◽  
Low Degrees ◽  
High Level

To investigate the factors controlling evolutionary differentiation within the genus Brassica, chromosome pairing in amphihaploids from crosses between the three elementary diploid species B. campestris (AA), B. oleracea (CC), and B. nigra (BB) was analyzed. The amphihaploid AC showed a high amount of pairing, while the two amphihaploids AB and BC, both including the genome of B. nigra, exhibited only low degrees of chromosome association. By the occurrence of tetra- and penta-valents, auto- as well as allo-syndetic pairing was demonstrated to exist in the AC amphihaploid. True homologous pairing between the genomes A and C was deduced from the occurrence of chromosomal interchange configurations. Although the genomes of B. oleracea and B. campestris are evolutionarily distinct, as shown by the different number and structure of their chromosomes, their close relationship is readily evident from the high level of pairing observed in the AC amphihaploids. On the other hand, the much lower pairing within the amphihaploids including the B genome is unexpected in view of the hypothesis of a common ancestor for all three of the cultivated Brassica diploids from an ancestral genome with x = 6 chromosomes. It is discussed whether B. nigra is indeed more distantly related to the two other species or whether this genome carries a suppressor of chromosome pairing.Key words: chromosome pairing, amphihaploids, evolutionary relations.

Assessment of chromosome associations in haploids and their parental accessions in Hordeum

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 204-210 ◽  
Author(s):  
R. von Bothmer ◽  
N. C. Subrahmanyam
Keyword(s):  
Genetic Variation ◽  
Chromosome Pairing ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Homoeologous Chromosome ◽  
Homologous Pairing ◽  
Homoeologous Chromosome Pairing ◽  
Chromosome Associations

Meiotic pairing was studied in the following species and their haploid derivatives: Hordeum cordobense 2x, H. marinum 2x and 4x, H. secalinum 4x, H. capense 4x, H. jubatum 4x, H. brachyantherum 4x and 6x, H. lechleri 6x, and H. procerum 6x. The study revealed (i) homologous pairing in diploid species and very little nonhomologous associations in their mono-haploids; (ii) the alloploid nature of the polyploid taxa; (iii) a certain degree of homoeologous pairing in polyhaploids despite the diploid-like meiotic behaviour of the polyploids; (iv) genetic variation in the suppression of homoeologous chromosome pairing in different Hordeum species.Key words: Hordeum, meiotic pairing, haploids.

scholarly journals LATENT NONSTRUCTURAL DIFFERENTIATION AMONG HOMOLOGOUS CHROMOSOMES AT THE DIPLOID LEVEL: CHROMOSOME 6Be OF AEGILOPS LONGISSIMA

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 579-592
Author(s):  
Rama S Kota ◽  
Patrick E McGuire ◽  
Jan Dvořák
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Constitutive Heterochromatin ◽  
Diploid Species ◽  
Triticum Aestivum L ◽  
Homologous Chromosomes ◽  
B Genome ◽  
Aegilops Longissima ◽  
Chinese Spring Wheat ◽  
Diploid Level

ABSTRACT Previous work has shown that chromosome pairing at metaphase I (MI) of wheat homologous chromosomes from different inbred lines (heterohomologous chromosomes) is reduced relative to that between homologous chromosomes within an inbred line (euhomologous chromosomes). In order to determine if a potential for this phenomenon exists in diploid species closely related to the wheat B genome, MI chromosome pairing was investigated between euhomologous and heterohomologous 6Be (=6Se) chromosomes, each from a different population of Aegilops longissima Schweinf. et Muschl. (2n = 2x = 14) substituted for chromosome 6B of Chinese Spring wheat (Triticum aestivum L., 2n = 6x = 42). Euhomologous and heterohomologous monotelodisomics, i.e., plants with one complete chromosome 6Be and a telosome of either 6Bep or 6Beq, were constructed in the isogenic background of Chinese Spring. Pairing at MI of the Ae. longissima chromosomes was reduced in heterohomologous monotelodisomics compared to that in the corresponding euhomologous monotelodisomics. The remaining 20 pairs of Chinese Spring chromosomes paired equally well in the euhomologous and heterohomologous monotelodisomics. Thus, the cause of the reduced pairing must reside specifically in the Ae. longissima heterohomologues. In the hybrids between the Ae. longissima lines that contributed the substituted chromosomes, pairing between the heterohomologous chromosomes was normal and did not differ from that of the euhomologous chromosomes. These data provide evidence that a potential for reduced pairing between the heterohomologues is present in the diploid species, but is expressed only in the polyploid wheat genetic background. The reduction in heterohomologous chromosome pairing was greater in the p arm than in the q arm, exactly as in chromosome 6B of wheat. It is concluded that the reduced pairing between Ae. longissima heterohomologues has little to do with constitutive heterochromatin. The value of chromosome pairing as an unequivocal means of determining the origin of genomes in polyploid plants is questioned.

The genomic relationship of the diploid Bromus variegatus to Bromus inermis

1984 ◽  
Vol 26 (4) ◽  
pp. 469-474 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Chromosome Pairing ◽  
Diploid Species ◽  
Bromus Inermis ◽  
Genomic Relationship ◽  
Diploid Genome ◽  
B Genome ◽  
Hybrid Plants ◽  
Relationship Of ◽  
Genomic Model

The diploid species Bromus variegatus Bieb. was crossed to Bromus inermis Leyss (4x, 8x). Chromosome pairing in each of the six F1 hybrid plants of B. variegatus × B. inermis (4x) fit a 2:1 genomic model of chromosome pairing, which indicated that the B. variegatus genome was more closely related to the A or B genome of B. inermis than A and B were related to each other. A breakdown of microsporocytes was observed in the B. variegatus × B. inermis (8x) hybrid. However, chromosome pairing suggested that the B. variegatus genome was differentiated from the A and B genomes of octoploid B. inermis.Key words: Bromus, diploid, genome, affinity.

CHROMOSOME RELATIONSHIPS BETWEEN THE CULTIVATED OAT AVENA SATIVA (6x) AND A. VENTRICOSA (2x)

1970 ◽  
Vol 12 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Hugh Thomas
Keyword(s):  
Chromosome Pairing ◽  
Avena Sativa ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Hexaploid Species ◽  
C Genome

Chromosome pairing in the F1 hybrid between the cultivated oat Avena sativa and a diploid species A. ventricosa, and in the derived amphiploid, shows that the diploid species is related to one of the genomes of the hexaploid species. The amount of chromosome pairing observed in complex interamphiploid hybrids demonstrates further that A. ventricosa is related to the C. genome of A. sativa. However, the chromosomes of the diploid species have become differentiated from that of the C genome of A. sativa and this is readily apparent in the meiotic behaviour of both the F1 hybrid and the amphiploid.

A Centromeric Tandem Repeat Family Originating From a Part of Ty3/gypsy-Retroelement in Wheat and Its Relatives

Genetics ◽  
2003 ◽  
Vol 164 (2) ◽  
pp. 665-672 ◽  
Author(s):  
Zhi-Jun Cheng ◽  
Minoru Murata
Keyword(s):  
In Situ Hybridization ◽  
Tandem Repeats ◽  
Diploid Species ◽  
Upstream Region ◽  
Aegilops Speltoides ◽  
Repeat Family ◽  
B Genome ◽  
Intervening Sequences ◽  
Wild Diploid Species

AbstractFrom a wild diploid species that is a relative of wheat, Aegilops speltoides, a 301-bp repeat containing 16 copies of a CAA microsatellite was isolated. Southern blot and fluorescence in situ hybridization revealed that ∼250 bp of the sequence is tandemly arrayed at the centromere regions of A- and B-genome chromosomes of common wheat and rye chromosomes. Although the DNA sequence of this 250-bp repeat showed no notable homology in the databases, the flanking or intervening sequences between the repeats showed high homologies (>82%) to two separate sequences of the gag gene and its upstream region in cereba, a Ty3/gypsy-like retroelement of Hordeum vulgare. Since the amino acid sequence deduced from the 250 bp with seven CAAs showed some similarity (∼53%) to that of the gag gene, we concluded that the 250-bp repeats had also originated from the cereba-like retroelements in diploid wheat such as Ae. speltoides and had formed tandem arrays, whereas the 300-bp repeats were dispersed as a part of cereba-like retroelements. This suggests that some tandem repeats localized at the centromeric regions of cereals and other plant species originated from parts of retrotransposons.

scholarly journals Global Expansion of Linezolid-Resistant Coagulase-Negative Staphylococci

2021 ◽  
Vol 12 ◽  
Author(s):  
Vladimir Gostev ◽  
Semen Leyn ◽  
Alexander Kruglov ◽  
Daria Likholetova ◽  
Olga Kalinogorskaya ◽  
...  
Keyword(s):  
Compact Group ◽  
Common Ancestor ◽  
Bioinformatic Analysis ◽  
Coagulase Negative Staphylococci ◽  
Single Nucleotide ◽  
Warm Blooded Animal ◽  
Long Time ◽  
High Level ◽  
Rooted Phylogenetic Tree ◽  
Emergence Of Resistance

Coagulase-negative staphylococci (CoNS) for a long time were considered avirulent constituents of the human and warm-blooded animal microbiota. However, at present, S. epidermidis, S. haemolyticus, and S. hominis are recognized as opportunistic pathogens. Although linezolid is not registered for the treatment of CoNS infections, it is widely used off-label, promoting emergence of resistance. Bioinformatic analysis based on maximum-likelihood phylogeny and Bayesian clustering of the CoNS genomes obtained in the current study and downloaded from public databases revealed the existence of international linezolid-resistant lineages, each of which probably had a common predecessor. Linezolid-resistant S. epidermidis sequence-type (ST) 2 from Russia, France, and Germany formed a compact group of closely related genomes with a median pairwise single nucleotide polymorphism (SNP) difference of fewer than 53 SNPs, and a common ancestor of this lineage appeared in 1998 (1986–2006) before introduction of linezolid in practice. Another compact group of linezolid-resistant S. epidermidis was represented by ST22 isolates from France and Russia with a median pairwise SNP difference of 40; a common ancestor of this lineage appeared in 2011 (2008–2013). Linezolid-resistant S. hominis ST2 from Russia, Germany, and Brazil also formed a group with a high-level genome identity with median 25.5 core-SNP differences; the appearance of the common progenitor dates to 2003 (1996–2012). Linezolid-resistant S. hominis isolates from Russia demonstrated associated resistance to teicoplanin. Analysis of a midpoint-rooted phylogenetic tree of the group confirmed the genetic proximity of Russian and German isolates; Brazilian isolates were phylogenetically distant. repUS5-like plasmids harboring cfr were detected in S. hominis and S. haemolyticus.

scholarly journals Bioindication of soil of unauthorized landfills in the Carpathian region

2021 ◽  
Author(s):  
L. Symochko ◽  
О. Hafiiyak ◽  
O. Demyanyuk
Keyword(s):  
Solid Waste ◽  
Ecological Status ◽  
Biosphere Reserve ◽  
Soil Microbial ◽  
Microbiological Processes ◽  
Waste Storage ◽  
Carpathian Region ◽  
Close Relationship ◽  
Organotrophic Bacteria ◽  
High Level

The article presents the results of monitoring the area adjacent to the Carpathian Biosphere Reserve for the detection of unauthorized landfills and examines the ecological status of these soils. Four unauthorized landfills of solid waste in Pidhirna, Stanislav, Steryshora, and Feresok tracts with an area of 0.15 to 1.5 ha with a waste accumulation period of 12–22 years and different morphological composition which had a significant impact on the ecological status of the soil have been identified. Bioindication methods have shown changes in the soil microbial cenoses under the direct influence of unauthorized landfills of solid waste, namely increased the number of organotrophic bacteria and micromycetes and decreased number of nitrogen-fixing microorganisms. The highest number of bacteria using nitrogen of organic compounds (25.36–28.61 million CFU/g soil) and micromycetes (51.8–76.8 thousand CFU/g soil) was fixed in the soils in the tract PidhirnaandFeresok with advantage of 1.5–1.7 times and 2.5–3.8 times compared to the soil of the protected area. Increasing the number of pedotrophic and oligotrophic microorganisms and microorganisms that assimilate organic forms of nitrogen, on average, 2.70, 2.84 and 1.48 times has been affected the direction of the main soil-microbiological processes. The coefficient of oligotrophicity varied in the range of 0.21–0.30, mineralization-immobilization one — 1.22–1.38, pedotrophic one — 0.55–0.96 with a maximum in the soil of the landfill in the tracts of Feresok and Pidhirna, which indicates the strengthening of microbiological processes of mineralization and decomposition of soil organic matter, including humus compounds. A close relationship was established between the duration of solid waste storage in a certain area and the level of soil phytotoxicity (r = 0.92). In the soil of landfills in Pidhirna, Steryshora and Feresok tracts, the phytotoxicity index is significant (over 50%), which indicates a high level of soil ecosystem pollution and increased environmental risks in the area of unauthorized accumulation of solid waste.

scholarly journals Microtomographic Analysis of Impact Damage in FRP Composite Laminates: A Comparative Study

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
M. Alemi-Ardakani ◽  
A. S. Milani ◽  
S. Yannacopoulos ◽  
L. Bichler ◽  
D. Trudel-Boucher ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Impact Damage ◽  
Glass Fibers ◽  
Impact Testing ◽  
Frp Composites ◽  
Frp Composite ◽  
Flexural Testing ◽  
Close Relationship ◽  
High Level ◽  
Tomographic Analysis

With the advancement of testing tools, the ability to characterize mechanical properties of fiber reinforced polymer (FRP) composites under extreme loading scenarios has allowed designers to use these materials in high-level applications more confidently. Conventionally, impact characterization of composite materials is studied via nondestructive techniques such as ultrasonic C-scanning, infrared thermography, X-ray, and acoustography. None of these techniques, however, enable 3D microscale visualization of the damage at different layers of composite laminates. In this paper, a 3D microtomographic technique has been employed to visualize and compare impact damage modes in a set of thermoplastic laminates. The test samples were made of commingled polypropylene (PP) and glass fibers with two different architectures, including the plain woven and unidirectional. Impact testing using a drop-weight tower, followed by postimpact four-point flexural testing and nondestructive tomographic analysis demonstrated a close relationship between the type of fibre architecture and the induced impact damage mechanisms and their extensions.

2021 AAHA Working, Assistance, and Therapy Dog Guidelines

2021 ◽  
Vol 57 (6) ◽  
pp. 253-277
Author(s):  
Cynthia M. Otto ◽  
Tracy Darling ◽  
Lisa Murphy ◽  
Zenithson Ng ◽  
Bess Pierce ◽  
...  
Keyword(s):  
Therapy Dogs ◽  
Goal Directed Therapy ◽  
Therapy Dog ◽  
Extensive Training ◽  
Close Relationship ◽  
Working Dogs ◽  
Scent Detection ◽  
Physical Limitations ◽  
High Level ◽  
Consensus Report

ABSTRACT The guidelines are the first comprehensive consensus report on veterinary healthcare recommendations for working, assistance, and therapy dogs. This category of canine patients includes a broad assortment of animals, some with well-defined functions and others that provide a more generalized support role. The guidelines discuss recommendations for dogs trained for protection, odor/scent detection, service functions for people with diagnosed disabilities or physical limitations, emotional support, and therapeutic intervention. Although the term is often used to describe dogs providing animal-assisted activities, true therapy dogs provide goal-directed therapy, often under the supervision of a healthcare professional such as an occupational therapist or psychologist. Many working dogs undergo extensive training and have rigorous physical demands placed upon them. These factors make working, assistance, and therapy dogs inherently valuable and impose a need for a high level of primary veterinary care as described in the guidelines. Because working dogs have a particularly close relationship with their handlers, a trust relationship between the practice team and the working-dog client is imperative.

Online Community Bonds as a Method of Mitigating Toxicity in an Interactive Livestream

2020 ◽  
pp. 303-322
Author(s):  
Olivia Rines
Keyword(s):  
Online Community ◽  
Well Being ◽  
Significant Issue ◽  
Close Relationship ◽  
High Level

Toxicity—aggressive, discriminatory, or hostile behavior that impacts a group or community—is a significant issue on the livestreaming platform Twitch, where a single toxic utterance can disrupt the dynamic between a streamer and their fans. This chapter examines the ways in which a female Twitch streamer combats issues of toxicity by creating and supporting a fan community that is heavily invested in her and therefore endeavors to conform to the norms and regulations of her community. Through the analysis of a single two-hour stream, this chapter considers the ways in which a streamer can balance the appearance of a close relationship with her community with a high level of moderation and regulation to resist toxic behavior and thus ensure her and her fan community's well-being and happiness.

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