scholarly journals Position Effects of Ribosomal RNA Multigene Loci on Meiotic Recombination in Wheat

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 1105-1113 ◽  
Author(s):  
Ming-Cheng Luo ◽  
Zu-Li Yang ◽  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Ribosomal Rna ◽  
Meiotic Recombination ◽  
Recombination Rate ◽  
Wheat Chromosome ◽  
Proximal Region ◽  
Rrna Genes ◽  
Position Effects ◽  
Chromosome Arm ◽  
Genetic Length

Abstract Homeologous wheat chromosome arms that differ by the presence or absence of a Nor locus or greatly differ in the numbers of copies of rRNA genes per Nor locus show conspicuous differences in the distribution of recombination. To assess directly the position effects of Nor loci on recombination across chromosome arms, a Triticum monococcum Nor9 haplotype was substituted for Triticum aestivum Nor9 haplotypes on two T. aestivum 1A chromosomes in the isogenic background of cv Chinese Spring. The numbers of rRNA genes in the 1A Nor9 haplotypes are greatly reduced relative to the T. monococcum haplotype. The substitution resulted in reduced recombination rate in the vicinity of the Nor9 locus. An intra-arm compensatory increase was observed in the proximal region of the arm so that the genetic length of the chromosome arm was unchanged. These findings suggest that Nor loci suppress recombination in their vicinity and change recombination patterns in Nor-bearing chromosome arms.

Molecular cytogenetic analysis of intergeneric chromosomal translocations between wheat (Triticum aestivum L.) and Dasypyrum villosum arising from tissue culture

Genome ◽  
2000 ◽  
Vol 43 (5) ◽  
pp. 756-762 ◽  
Author(s):  
Hong-Jie Li ◽  
Bei-Hai Guo ◽  
Yi-Wen Li ◽  
Li-Qun Du ◽  
Xu Jia ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Tissue Culture ◽  
In Situ Hybridization ◽  
Wheat Chromosome ◽  
Triticum Aestivum L ◽  
Average Frequency ◽  
Dasypyrum Villosum ◽  
Chromosome Translocations ◽  
Chromosome Arm

Fluorescence in situ hybridization (FISH) was applied with total genomic DNA extracted from Dasypyrum villosum (L.) Candargy as a probe to characterize chromosome translocations arising from tissue culture in hybrids of Triticum aestivum × (T. durum - D. villosum, amphiploid). Chromosome translocations between wheat and D. villosum occurred in callus cells at an average frequency of 1.9%. Translocations existed not only in callus cells but also in regenerants. Three plants with translocation chromosomes were characterized among 66 regenerants of T. aestivum 'Chinese Spring' × 'TH1W' and 'NPFP' × 'TH1'. One of them proved to be a reciprocal translocation with an exchange of about one third of a wheat chromosome arm with about one half of a chromosome arm of D. villosum. The breakpoints of the other two translocations were located at, or near centromeres. The results are similar for both callus cells and regenerants and provide further evidence that translocations take place in tissue culture. Other structural chromosomal changes, for example, fragments, telocentrics, dicentromeres, and deletions, as well as numerical alterations including aneuploidy and polyploidy were recorded both in callus cells and regenerants.Key words: wheat, Dasypyrum villosum, translocation, genomic in situ hybridization, tissue culture.

Meiotic pairing control in wheat–rye hybrids. I. Effect of different wheat chromosome arms of homoeologous groups 3 and 5

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 72-75 ◽  
Author(s):  
C. Cuadrado ◽  
C. Romero ◽  
J. R. Lacadena
Keyword(s):  
Triticum Aestivum ◽  
Secale Cereale ◽  
Wheat Chromosome ◽  
Suppressive Effect ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Promoting Effect ◽  
Promotive Effect ◽  
Chromosome Arm ◽  
Homoeologous Chromosomes

Wheat–rye hybrids were analyzed to study how the homoeologous-pairing control of wheat is altered when specific regulators of groups 3 and 5 are lacking or mutated. Lack of the 3DS chromosome arm and the ph2b mutation showed the most significant effect, due to a deficiency or inactivity of the Ph2 suppressor. The 3DL, 5AS, and 5BS chromosome arms have a promoting effect, 5BS being the most effective. A weak suppressive effect of 3AS and 3AL is proposed, and a promotive effect of 5DS was not ruled out. The suppressive effect of 3BS is discussed.Key words: Triticum aestivum, Secale cereale, homoeologous chromosomes, genetic pairing regulation.

Phylogeny of hymenolepidids (Cestoda: Cyclophyllidea) from mammals: sequences of 18S rRNA and COI genes confirm major clades revealed by the 28S rRNA analyses

2021 ◽  
Vol 95 ◽  
Author(s):  
B. Neov ◽  
G.P. Vasileva ◽  
G. Radoslavov ◽  
P. Hristov ◽  
D.T.J. Littlewood ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
18S Rrna ◽  
Phylogenetic Analyses ◽  
The Other ◽  
Rrna Genes ◽  
Host Switching ◽  
28S Rrna ◽  
Mitochondrial Cytochrome ◽  
Rapid Radiation ◽  
18S Rrna Genes

Abstract The aim of the study is to test a hypothesis for the phylogenetic relationships among mammalian hymenolepidid tapeworms, based on partial (D1–D3) nuclear 28S ribosomal RNA (rRNA) genes, by estimating new molecular phylogenies for the group based on partial mitochondrial cytochrome c oxidase I (COI) and nuclear 18S rRNA genes, as well as a combined analysis using all three genes. New sequences of COI and 18S rRNA genes were obtained for Coronacanthus integrus, C. magnihamatus, C. omissus, C. vassilevi, Ditestolepis diaphana, Lineolepis scutigera, Spasskylepis ovaluteri, Staphylocystis tiara, S. furcata, S. uncinata, Vaucherilepis trichophorus and Neoskrjabinolepis sp. The phylogenetic analyses confirmed the major clades identified by Haukisalmi et al. (Zoologica Scripta 39: 631–641, 2010): Ditestolepis clade, Hymenolepis clade, Rodentolepis clade and Arostrilepis clade. While the Ditestolepis clade is associated with soricids, the structure of the other three clades suggests multiple evolutionary events of host switching between shrews and rodents. Two of the present analyses (18S rRNA and COI genes) show that the basal relationships of the four mammalian clades are branching at the same polytomy with several hymenolepidids from birds (both terrestrial and aquatic). This may indicate a rapid radiation of the group, with multiple events of colonizations of mammalian hosts by avian parasites.

scholarly journals Characterization, Comparative Analysis and Phylogenetic Implications of Mitogenomes of Fulgoridae (Hemiptera: Fulgoromorpha)

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1185
Author(s):  
Wenqian Wang ◽  
Huan Zhang ◽  
Jérôme Constant ◽  
Charles R. Bartlett ◽  
Daozheng Qin
Keyword(s):  
Control Region ◽  
Ribosomal Rna ◽  
Phylogenetic Analyses ◽  
Start Codon ◽  
Rrna Genes ◽  
Rich Region ◽  
Protein Coding ◽  
Phylogenetic Implications ◽  
Rna Genes ◽  
Unpaired Base

The complete mitogenomes of nine fulgorid species were sequenced and annotated to explore their mitogenome diversity and the phylogenetics of Fulgoridae. All species are from China and belong to five genera: Dichoptera Spinola, 1839 (Dichoptera sp.); Neoalcathous Wang and Huang, 1989 (Neoalcathous huangshanana Wang and Huang, 1989); Limois Stål, 1863 (Limois sp.); Penthicodes Blanchard, 1840 (Penthicodes atomaria (Weber, 1801), Penthicodes caja (Walker, 1851), Penthicodes variegata (Guérin-Méneville, 1829)); Pyrops Spinola, 1839 (Pyrops clavatus (Westwood, 1839), Pyrops lathburii (Kirby, 1818), Pyrops spinolae (Westwood, 1842)). The nine mitogenomes were 15,803 to 16,510 bp in length with 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs) and a control region (A + T-rich region). Combined with previously reported fulgorid mitogenomes, all PCGs initiate with either the standard start codon of ATN or the nonstandard GTG. The TAA codon was used for termination more often than the TAG codon and the incomplete T codon. The nad1 and nad4 genes varied in length within the same genus. A high percentage of F residues were found in the nad4 and nad5 genes of all fulgorid mitogenomes. The DHU stem of trnV was absent in the mitogenomes of all fulgorids sequenced except Dichoptera sp. Moreover, in most fulgorid mitogenomes, the trnL2, trnR, and trnT genes had an unpaired base in the aminoacyl stem and trnS1 had an unpaired base in the anticodon stem. The similar tandem repeat regions of the control region were found in the same genus. Phylogenetic analyses were conducted based on 13 PCGs and two rRNA genes from 53 species of Fulgoroidea and seven outgroups. The Bayesian inference and maximum likelihood trees had a similar topological structure. The major results show that Fulgoroidea was divided into two groups: Delphacidae and ((Achilidae + (Lophopidae + (Issidae + (Flatidae + Ricaniidae)))) + Fulgoridae). Furthermore, the monophyly of Fulgoridae was robustly supported, and Aphaeninae was divided into Aphaenini and Pyropsini, which includes Neoalcathous, Pyrops, Datua Schmidt, 1911, and Saiva Distant, 1906. The genus Limois is recovered in the Aphaeninae, and the Limoisini needs further confirmation; Dichoptera sp. was the earliest branch in the Fulgoridae.

scholarly journals Genetic variation in recombination rate in the pig

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Martin Johnsson ◽  
Andrew Whalen ◽  
Roger Ros-Freixedes ◽  
Gregor Gorjanc ◽  
Ching-Yi Chen ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Recombination Rate ◽  
Large Scale ◽  
Genome Wide Association Study ◽  
Genetic Material ◽  
A Genome ◽  
Pig Genome ◽  
Genetic Length ◽  
Trait Locus ◽  
Genomic Regions

Abstract Background Meiotic recombination results in the exchange of genetic material between homologous chromosomes. Recombination rate varies between different parts of the genome, between individuals, and is influenced by genetics. In this paper, we assessed the genetic variation in recombination rate along the genome and between individuals in the pig using multilocus iterative peeling on 150,000 individuals across nine genotyped pedigrees. We used these data to estimate the heritability of recombination and perform a genome-wide association study of recombination in the pig. Results Our results confirmed known features of the recombination landscape of the pig genome, including differences in genetic length of chromosomes and marked sex differences. The recombination landscape was repeatable between lines, but at the same time, there were differences in average autosome-wide recombination rate between lines. The heritability of autosome-wide recombination rate was low but not zero (on average 0.07 for females and 0.05 for males). We found six genomic regions that are associated with recombination rate, among which five harbour known candidate genes involved in recombination: RNF212, SHOC1, SYCP2, MSH4 and HFM1. Conclusions Our results on the variation in recombination rate in the pig genome agree with those reported for other vertebrates, with a low but nonzero heritability, and the identification of a major quantitative trait locus for recombination rate that is homologous to that detected in several other species. This work also highlights the utility of using large-scale livestock data to understand biological processes.

scholarly journals Evaluation of 16S, map1 and pCS20 probes for detection of Cowdria and Ehrlichia species

1999 ◽  
Vol 122 (2) ◽  
pp. 323-328 ◽  
Author(s):  
M. T. E. P. ALLSOPP ◽  
C. M. HATTINGH ◽  
S. W. VOGEL ◽  
B. A. ALLSOPP
Keyword(s):  
16S Rrna ◽  
Ribosomal Rna ◽  
Pcr Amplification ◽  
16S Ribosomal Rna ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Amblyomma Hebraeum ◽  
Ribosomal Rna Gene ◽  
Group Iii ◽  
16S Ribosomal Rna Gene

A panel of 16S ribosomal RNA gene probes has been developed for the study of the epidemiology of heartwater; five of these detect different cowdria genotypes, one detects five distinct genotypes; one detects any Group III Ehrlichia species other than Cowdria and one detects any Group II Ehrlichia species. These probes have been used on PCR-amplified rickettsial 16S rRNA genes from over 200 Amblyomma hebraeum ticks. Control ticks were laboratory-reared and either uninfected or fed on sheep experimentally infected with different cowdria isolates, field ticks were collected from animals in heartwater-endemic areas. All tick-derived DNA samples were also examined by PCR amplification and probing for two other cowdria genes (map1 and pCS20) which have previously been used for heartwater epidemiology. This paper describes the first direct comparison of all currently available DNA probes for heartwater-associated organisms.

scholarly journals Genomic Analysis of the Snn1 Locus on Wheat Chromosome Arm 1BS and the Identification of Candidate Genes

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Leela Reddy ◽  
Timothy L. Friesen ◽  
Steven W. Meinhardt ◽  
Shiaoman Chao ◽  
Justin D. Faris
Keyword(s):  
Candidate Genes ◽  
Genomic Analysis ◽  
Wheat Chromosome ◽  
Chromosome Arm

scholarly journals Identification of theVERNALIZATION 4gene reveals the origin of spring growth habit in ancient wheats from South Asia

2015 ◽  
Vol 112 (39) ◽  
pp. E5401-E5410 ◽  
Author(s):  
Nestor Kippes ◽  
Juan M. Debernardi ◽  
Hans A. Vasquez-Gross ◽  
Bala A. Akpinar ◽  
Hikment Budak ◽  
...  
Keyword(s):  
South Asia ◽  
Rna Binding ◽  
Growth Habit ◽  
Regulatory Region ◽  
Proximal Region ◽  
Induced Mutations ◽  
Wheat Varieties ◽  
Density Mapping ◽  
Chromosome Arm ◽  
Delayed Flowering

Wheat varieties with a winter growth habit require long exposures to low temperatures (vernalization) to accelerate flowering. Natural variation in four vernalization genes regulating this requirement has favored wheat adaptation to different environments. The first three genes (VRN1–VRN3) have been cloned and characterized before. Here we show that the fourth gene,VRN-D4, originated by the insertion of a ∼290-kb region from chromosome arm 5AL into the proximal region of chromosome arm 5DS. The inserted 5AL region includes a copy ofVRN-A1that carries distinctive mutations in its coding and regulatory regions. Three lines of evidence confirmed that this gene isVRN-D4: it cosegregated withVRN-D4in a high-density mapping population; it was expressed earlier than otherVRN1genes in the absence of vernalization; and induced mutations in this gene resulted in delayed flowering.VRN-D4was found in most accessions of the ancient subspeciesTriticum aestivumssp.sphaerococcumfrom South Asia. This subspecies showed a significant reduction of genetic diversity and increased genetic differentiation in the centromeric region of chromosome 5D, suggesting thatVRN-D4likely contributed to local adaptation and was favored by positive selection. Three adjacent SNPs in a regulatory region of theVRN-D4first intron disrupt the binding ofGLYCINE-RICH RNA-BINDING PROTEIN 2(TaGRP2), a known repressor ofVRN1expression. The same SNPs were identified inVRN-A1alleles previously associated with reduced vernalization requirement. These alleles can be used to modulate vernalization requirements and to develop wheat varieties better adapted to different or changing environments.

Basonuclin is associated with the ribosomal RNA genes on human keratinocyte mitotic chromosomes

1999 ◽  
Vol 112 (18) ◽  
pp. 3039-3047 ◽  
Author(s):  
H. Tseng ◽  
J.A. Biegel ◽  
R.S. Brown
Keyword(s):  
Ribosomal Rna ◽  
Zinc Fingers ◽  
Hair Follicles ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Control Element ◽  
Rrna Gene ◽  
Metaphase Chromosomes ◽  
Acrocentric Chromosomes ◽  
Rna Genes

Basonuclin is a zinc finger protein mainly expressed in keratinocytes of the basal layer of epidermis and the outer root sheath of hair follicles. It is also found in abundance in the germ cells of testis and ovary. In cultured keratinocytes, basonuclin is associated with chromatin in all phases of the cell cycle, including mitosis. By immunocytochemical methods, we demonstrate here that in mitosis basonuclin is associated with the short arms of the acrocentric chromosomes and with other loci on many metaphase chromosomes of human keratinocytes. Using the evolutionarily highly conserved N-terminal pair of zinc fingers in an electrophoresis mobility shift assay, we demonstrate that the DNA target sequences of basonuclin on the acrocentric chromosomes are likely to be within the promoter region of the 45S rRNA gene transcription unit. DNase I footprinting shows that basonuclin zinc fingers interact with the upstream control element of this promoter, which is necessary for the high level of transcription of the rRNA genes. This result suggests that basonuclin may be a tissue-specific transcription factor for the ribosomal RNA genes.

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