Ascospore abortion in crosses of Cochliobolus heterostrophus heterozygous for the virulence locus Tox1

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Charlotte R. Bronson
Keyword(s):  
Key Words ◽  
Reciprocal Translocation ◽  
High Frequency ◽  
Chromosome Rearrangement ◽  
Cochliobolus Heterostrophus ◽  
Bipolaris Maydis ◽  
Field Isolates

Crosses heterozygous for the virulence locus Tox1 show a high frequency of nonrandom ascospore abortion, in addition to a high frequency of random abortion seen in homozygous crosses. In crosses among closely related laboratory strains, the frequency of asci with eight mature, viable spores dropped from 35–47% of asci with mature spores in crosses homozygous for Tox1 to 3–17% in heterozygous crosses. Segregation for alternate alleles of Tox1 was 2:2 in 98% of asci with four viable spores. Patterns of abortion in crosses involving field isolates were similar to the patterns in crosses among laboratory strains. No recombinants between Tox1 and the abortion-inducing factor were detected among 112 progeny of laboratory strains. The results suggest that race T (TOX1) and race O (tox1) strains of C. heterostrophus differ by a chromosome rearrangement, possibly a reciprocal translocation, with a breakpoint at or near Tox1.Key words: fertility, T-toxin, Cochliobolus heterostrophus, Helminthosporium maydis, Bipolaris maydis, Drechslera maydis, chromosome rearrangement, reciprocal translocation.

A reciprocal translocation and possible insertion(s) tightly associated with host-specific virulence in Cochliobolus heterostrophus

Genome ◽  
1996 ◽  
Vol 39 (3) ◽  
pp. 549-557 ◽  
Author(s):  
Hsin-Ru Chang ◽  
Charlotte R. Bronson
Keyword(s):  
Reciprocal Translocation ◽  
Chromosome Rearrangement ◽  
Natural Populations ◽  
Toxin Production ◽  
Cochliobolus Heterostrophus ◽  
Pulsed Field ◽  
Field Isolates ◽  
Pulsed Field Electrophoresis ◽  
Additional Chromosome ◽  
Tight Association

A reciprocal translocation and one or more apparent insertions are shown to be tightly associated with Tox1, a locus controlling T-toxin production and host-selective virulence in race T of the maize pathogen Cochliobolus heterostrophus. Chromosome arrangements were examined by separating chromosomal DNAs of a variety of Tox+ and Tox− strains by pulsed-field gel electrophoresis and hybridizing with probes known to detect RFLPs genetically linked to Tox1. The existence of the translocation was demonstrated by chromosome hybridization patterns; the existence of the putative insertion(s) was deduced from chromosome migration rates. Both differences in chromosome arrangement were detected between 8 Tox+ and 8 Tox− near-isogenic laboratory strains, suggesting that the differences are tightly linked to Tox1. The reciprocal translocation was also detected between all 7 Tox+ and 8 Tox− field isolates examined, suggesting that the translocation is common in natural populations. The field isolates may also differ by the insertion(s); however, numerous additional chromosome size polymorphisms in the field isolates prevented a firm conclusion. The tight association of the translocation and insertion(s) with T-toxin production suggests that chromosome rearrangements may have been involved in the evolution of race T and Tox1. These genomic differences may be causally related to the previously reported reduced fitness of race T relative to race O on N-cytoplasm maize. Key words : chromosome rearrangement, southern corn leaf blight, pulsed-field electrophoresis, T-toxin, evolution.

Nonrandom abortion of ascospores containing alternate alleles at the Tox-1 locus of the fungal plant pathogen Cochliobolus heterostrophus

1985 ◽  
Vol 27 (4) ◽  
pp. 450-456 ◽  
Author(s):  
M. Taga ◽  
C. R. Bronson ◽  
O. C. Yoder
Keyword(s):  
Plant Pathogen ◽  
Toxin Production ◽  
Low Fertility ◽  
Cochliobolus Heterostrophus ◽  
Bipolaris Maydis ◽  
High Frequencies ◽  
Field Isolates ◽  
Fungal Plant Pathogen ◽  
Inducing Factors ◽  
Aberrant Segregation

Crosses involving lab strains of C. heterostrophus that were previously selected for improved fertility yielded high frequencies of four-spored asci and only occasional asci with the full set of eight spores. Fertility in crosses between field isolates was low. Most asci contained two haploid spores; no asci had more than four spores. We investigated the distribution of aborted spores with respect to the three defined genetic loci Mat (mating type), Alb-1 (albinism), and Tox-1 (T-toxin production) and determined the frequency of mitotic twins in four-spored asci. Nonrandom spore abortion was evident from the observations that 80–100% of four-spored asci contained two sets of twins (9% expected for random abortion of mitotic products) and up to 95% of four-spored asci segregated 2:2 for alleles at the Tox-1 locus (67% expected for random abortion of meiotic products), suggesting preferential recovery of nonsister meiotic products. Segregation in crosses between field isolates tended to be skewed in favor of the tox-1a allele (specifies no toxin production). Alleles at Mat and Alb-1 segregated as expected for random abortion of meiotic products in both types of crosses. Low fertility and aberrant segregation among progeny segregating for ability to produce T toxin are likely due in part to abortion-inducing factors linked to Tox-1.Key words: fertility, ascomycetes, T toxin, Helminthosporium maydis, Bipolaris maydis.

Features of obstetric and perinatal pathology at women with an undifferentiated dysplasia of connecting tissue

2017 ◽  
pp. 96-98
Author(s):  
A.L. Kostiuk ◽  
Keyword(s):  
Pregnant Women ◽  
Key Words ◽  
High Frequency ◽  
Clinical Laboratory ◽  
Perinatal Pathology

The objective: to study features of obstetric and perinitalny pathology at women with undifferentiated dysplasia of a connecting tissue. Patients and methods. 100 patients with clinical-laboratory signs of an undifferentiated dysplasia of connecting tissue are surveyed. On the basis of the received results of the patient were divided into two groups: the main – 50 women (expression of і6 points) whom regarded as patients with the expressed undifferentiated dysplasia of connecting tissue, and group of comparison – 50 women (expression <6 points) whom regarded as patients without the expressed undifferentiated dysplasia of connecting tissue. Results. Results of the conducted researches testify to the high frequency of obstetric and perinatal pathology at pregnant women with clinical-laboratory and functional signs of an undifferentiated dysplasia of connecting tissue. Conclusion. The received results are the basis for algorithm improvement the diagnostical and treatment-and-prophylactic actions at women with an undifferentiated dysplasia of connecting tissue. Key words: undifferentiated dysplasia of connecting tissue, obstetric and perinatal pathology.

Features of professional disease of women–medical workers

2017 ◽  
pp. 70-71
Author(s):  
A.S. Shelygin ◽  
Keyword(s):  
Key Words ◽  
Functional Assessment ◽  
High Frequency ◽  
Clinical Laboratory ◽  
State Of Health ◽  
Case Rate ◽  
Working Out ◽  
Doctors And Nurses

The objective: an assessment of a professional case rate of women–medical workers. Patients and methods. The complex clinical-laboratory and functional assessment of a state of health, including genesial, at 100 women of doctors of various specialties and at 100 women of average medical workers is carried out. Results. Results of the spent researches testifies to high frequency of professional disease of medical workers of a various link – doctors and nurses. Conclusion. The received results are necessary for considering by working out of algorithm of diagnostic and treatment-and-prophylactic actions. Key words: medical workers, professional disease.

scholarly journals Characterization of Natural Isolates of Bipolaris maydis Associated with Mating Types, Genetic Diversity, and Pathogenicity in Fujian Province, China

Plant Disease ◽  
2020 ◽  
Vol 104 (2) ◽  
pp. 323-329
Author(s):  
Yuli Dai ◽  
Lin Gan ◽  
Hongchun Ruan ◽  
Niuniu Shi ◽  
Yixin Du ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Mating Type ◽  
Dna Polymorphism ◽  
Sweet Corn ◽  
Issr Markers ◽  
Bipolaris Maydis ◽  
Fujian Province ◽  
Field Isolates ◽  
Rational Distribution

Due to the natural destructiveness and persistence of the southern corn leaf blight (SCLB) fungus Bipolaris maydis (Nisikado et Miyake) Shoem, the characterization of B. maydis field isolates is essential to guide the rational distribution of resistant materials in corn-growing regions. In the present study, 102 field isolates collected from seven locations covering the entire region of Fujian Province, China, were assessed for mating type distribution, genetic diversity, and pathogenicity toward local sweet corn cultivars. Mating type detection via polymerase chain reaction indicated that 36.3 and 63.7% of isolates were MAT1-1 and MAT1-2, respectively; more than 80% of these isolates were confirmed using cross assays with known mating type isolates. Thirteen intersimple sequence repeat (ISSR) markers within and among two mating type populations revealed a high level of DNA polymorphism for all combined isolates and between MAT1-1 and MAT1-2 populations. The MAT1-2 population was more diverse based on DNA polymorphism than the MAT1-1 population. The value of GST was 0.0070, ranging from 0.0399 to 0.3044 based on analysis of combined isolates and individual regional populations, respectively, suggesting the presence of genetic differentiation in the two mating type populations from different locations. Pathogenicity assays revealed that both MAT1-1 and MAT1-2 populations were pathogenic to all 11 local sweet corn cultivars tested in this study. The potential of sexual reproduction, existence of genetic diversity in the two mating type populations, and pathogenicity suggest that B. maydis populations have independently clonally adapted under natural field conditions during corn cultivation.

scholarly journals Studies on High Frequency Shoot Regeneration in Sesame (Sesamum indicum L.)

2012 ◽  
Vol 21 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Bangaramma S. Wadeyar ◽  
R. Lokesha
Keyword(s):  
Key Words ◽  
Shoot Regeneration ◽  
Plant Tissue ◽  
High Frequency ◽  
Sesamum Indicum ◽  
Direct Seeding ◽  
The Other ◽  
Seeding Method ◽  
Regeneration Response ◽  
High Sucrose

High frequency shoot regeneration was attempted in sesame (Sesamum indicum L. Pedaliaceae), using five genotypes/varieties viz. Tumkur and Gulbarga Locals (land races), W-II, E-8 and DS-1 (varieties). The hypocotyl-derived callus obtained through direct seeding method was placed on MS with five different treatments viz. pre-culture of callus on high sucrose (6 - 9%) for two weeks and transferring on to plain MS with 3% sucrose, MS with variable concentrations of TDZ alone, MS with constant TDZ and variable concentrations of BA and IAA, MS with variable concentrations of BA and IAA without TDZ, MS with ABA and AgNO3 and MS with BAP, NAA and AgNO3.  Highest frequency of cent per cent shoot regeneration was initiated in variety DS-1on MS containing NAA 2.5 mg/l, BAP 3.5 mg/l and 20 µM AgNO3 with 2.50 mean shoots/callus followed by 91.6% in variety W-II on MS containing 25 µM TDZ with 2.20 mean shoots/callus. The other treatments had poor shoot regeneration response. The results have been discussed in the light of sesame improvement through biotechnological ways.   Key words: Sesamum indicum, hypocotyl, high frequency,  shoot regeneration   D. O. I. 10.3329/ptcb.v21i1.9562   Plant Tissue Cult. & Biotech. 21(1): 45-52, 2011 (June)

The orientation behaviour of multiple chromosome configurations in acridid grasshoppers

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 292-308 ◽  
Author(s):  
B. John
Keyword(s):  
Key Words ◽  
Reciprocal Translocation ◽  
Chiasma Frequency ◽  
The Other ◽  
Robertsonian Fusion ◽  
Orientation Behaviour ◽  
Chiasma Distribution ◽  
First Time ◽  
Existing Data ◽  
Combined Data

The existing data on the behaviour of multiple chromosome configurations arising from single interchanges between either metacentric–telocentric or telocentric–telocentric nonhomologues in 10 species of acridid grasshoppers are compared with data from four new cases. Two of these new cases involve metacentric–telocentric exchanges but the other two, for the first time in acridids, deal with a reciprocal translocation between two nonhomologous metacentrics. The combined data are used to evaluate the factors that influence multiple orientation in this family of grasshoppers and reemphasize the importance of chiasma frequency and chiasma distribution for multiple behaviour. This conclusion is reinforced by a consideration of the known cases of chain of three multiples originating from the Robertsonian fusion of nonhomologous telocentrics in acridoids. Key words: acridid grasshoppers, multiple chromosome configurations, chiasma distribution, orientation behaviour.

Genetic and macromorphologic evidence bearing on the evolution of members of Carex section Vesicariae (Cyperaceae) and their natural hybrids

1993 ◽  
Vol 71 (3) ◽  
pp. 486-500 ◽  
Author(s):  
Bruce A. Ford ◽  
Peter W. Ball ◽  
Kermit Ritland
Keyword(s):  
Key Words ◽  
High Frequency ◽  
Genetic Distances ◽  
Natural Hybrids

A comparison of genetic distances between the short-beaked species (C. saxatilis, C. membranacea, and C. rotundata) and some long-beaked species (C. utriculata, C. rostrata, and C. vesicaria) of Carex section Vesicariae indicates that the short-beaked group is not monophyletic. Carex saxatilis is closely related to C. vesicaria, while C. membranacea and C. rotundata are related to C. utriculata. It is proposed that C. saxatilis is derived from a vesicaria-like ancestor, while C. membranacea and C. rotundata have evolved from a utriculata-like progenitor. Taxa identified as hybrids between various short- and long-beaked species are intermediate in morphology, heterozygous for diagnostic loci (which exhibited a high frequency of alternative alleles in the putative parents), and often sterile. On the basis of the evidence presented the following hybrids are recognized: C. × paludivagans (C. rotundata × utriculata); C. × stenolepis (incl. C. × grahamii, C. × mainensis, C. × anticostensis; C. saxatilis × vesicaria); C. × physocarpoides (C. saxatilis × utriculata); and C. membranacea × utriculata. Key words: Carex, evolution, hybridization, systematics, morphology, isozymes.

The Research on Chinese Automatic Segmentation

2013 ◽  
Vol 798-799 ◽  
pp. 818-821
Author(s):  
Huan Qin Li ◽  
Shi Tao Yan
Keyword(s):  
Natural Language ◽  
Key Words ◽  
Statistical Method ◽  
High Frequency ◽  
Fundamental Problem ◽  
Automatic Segmentation ◽  
Abstract Word ◽  
Word Segmentation ◽  
Key Issues

Abstract. Word Segmentation is a fundamental problem of the Chinese natural language progressing. Based on the analysis of the state on research and key issues of it .The paper introduces a tree structure statistical method of word frequency, which enables key words to match one another highly-efficiently. by which we can rapidly express texts as the set of high-frequency words,so the classification of texts is conveniently reached.

The Key Concept of “Preparation” in K. K. Rokossovsky’s Memoir “Soldier’s Duty”

2021 ◽  
pp. 64-71
Author(s):  
Ma Ruye ◽  
Keyword(s):  
Key Words ◽  
High Frequency ◽  
Special Role ◽  
Evaluation Tool ◽  
High Importance ◽  
Dominant Component ◽  
Frequency Of Use ◽  
The World ◽  
Key Concepts

The defining feature of memoirs as a genre is the understanding of the events and the author’s own role in them. The world of the language personality of the author-narrator becomes the dominant component, which forms the meaning of the text. One of the possibilities of its linguistic study is to rely on key concepts, which are implemented by some lexical units, reflecting the worldview of the narrator and showing the conceptual and idiostylistic nature of the text. Studying military memoirs of Marshal Rokossovsky allowed to reveal a special role of the word preparation, which has a high frequency of use and is of a high importance as an evaluation tool. It may be considered one of the key words of the text because it refl ects one of the major areas of focus of Rokossovsky during the war. Thus, the meaning of the text in the genre of memoirs and personality of its creator can be interpreted by considering the important components in the activities of the author-narrator. One concept predominates the meaning of their work and becomes one of the key-concepts. From the perspective of this key concept the author evaluates events and their participants as positive or negative.

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