Genetic implications of current models of somatic nuclear division in fungi

1972 ◽  
Vol 50 (6) ◽  
pp. 1337-1347 ◽  
Author(s):  
Alan W. Day
Keyword(s):  
Nuclear Division ◽  
Crossing Over ◽  
Somatic Segregation ◽  
The Third ◽  
Chromosome Distribution ◽  
Experimental Approaches ◽  
Distribution Studies

The unusual two-track type of division which is widespread in most fungi other than Phycomycetes is described. Three models which attempt to account for this type of division are discussed in relation to (i) genetical observations on somatic segregation and (ii) chromosome distribution studies which predict that chromosomes of similar genetic 'age' move as a set. The feasibility of two of the models which postulate that the chromosomes are linked in chains is discussed in the light of our knowledge of mitotic crossing-over and haploidization. The third model (Robinow and Caten 1969) is more orthodox and differs from classical mitosis only in the presence of a narrow intranuclear spindle around which the chromosomes attach randomly and disjoin asynchronously. Future experimental approaches to distinguish between these models and to define the mechanism of division more completely are suggested.

SEX AND CROSSING OVER IN LINKAGE GROUP III OF TRIBOLIUM CASTANEUM

1977 ◽  
Vol 19 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Alexander Sokoloff
Keyword(s):  
Sex Differences ◽  
Linkage Group ◽  
Tribolium Castaneum ◽  
Relative Position ◽  
Genetic Background ◽  
Crossing Over ◽  
Group Iii ◽  
The Third ◽  
Main Factors ◽  
Coleoptera Tenebrionidae

The relative position of the genes black (b), light ocular diaphragm (lod) and aureate (au) for the third linkage group of T. castaneum (Herbst) (Coleoptera, Tenebrionidae) has been determined as b – lod – au. The distances between the various genes vary, depending on the cross. The b++/+ lod au ♂ × + lod au/+ lod au ♀ crosses give the following recombination values: au – lod = 18.32 ± 1.21%; b – lod = 21.05 ± 1.51% and b – au = 37.43 ± 1.27%. The reciprocal crosses give au – lod = 27.67 ± 1.62%; b – lod = 13.97 ± 1.26% and b – au = 39.79 ± 1.78%. For the larger distances encompassed in the b – au region the recombination values in the two sexes were not significantly different. For the shorter b – lod region the recombination values were significantly larger in the females than in the males, while for the adjacent lod – au region the opposite was true. On the basis of the current literature it would appear that the main factors contributing to these sex differences in recombination are the modifiers which are different in the genetic background of the two sexes.

RELATIONS BETWEEN FACTORS CONTROLLING CROSSING OVER AND MUTABILITY IN MALES OF DROSOPHILA ANANASSAE

Genetics ◽  
1983 ◽  
Vol 104 (1) ◽  
pp. 95-112
Author(s):  
Claude W Hinton
Keyword(s):  
Regional Distribution ◽  
The Other ◽  
Drosophila Ananassae ◽  
Crossing Over ◽  
The Third

ABSTRACT Several stocks, selected because they carried previously identified factors governing either crossing over in males or mutability, were examined to determine whether the effects of these factors are restricted to one or the other process. Neither of two dominant enhancers of male crossing over had detectable effects on Minute mutation frequencies among progenies of assayed F1 males. Genetically equivalent F1 males monitored for crossing over showed no unequivocal effect of either of three mutators (two dominant and one extrachromosomal) or of a suppressor of mutability. However, one combination of a dominant crossover enhancer with a dominant mutator showed synergistic increases in both crossover and Minute frequencies, and the possibility exists that a single extrachromosomally transmitted element suppresses both male crossing over and mutability. This suppressor element (or elements) had been previously diagnosed in the pc stock which, in this study, was discovered to have also a dominant enhancer of male crossing over and a dominant mutator occupying separable loci in the third chromosome. The pc enhancer of male crossing over differs from the dominant enhancer in another stock with respect to the regional distribution of crossovers, and the pc mutator is distinguished from another 3-linked mutator by its preferential induction of mutations at the Delta locus.

Nonlinear Vibrations of a Composite Beam in Large Displacements: Analytical, Numerical, and Experimental Approaches

2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Mattia Utzeri ◽  
Marco Sasso ◽  
Gianluca Chiappini ◽  
Stefano Lenci
Keyword(s):  
Composite Beam ◽  
Nonlinear Vibrations ◽  
Time History ◽  
Element Model ◽  
Lumped Mass ◽  
The Third ◽  
Amplitude Vibration ◽  
Large Amplitude Vibration ◽  
Experimental Approaches ◽  
The Finite Element Model

Abstract This paper investigates the nonlinear dynamic behavior of a cantilever beam made of composite material without and with lumped mass fixed along its length. The analysis compares the results coming from analytical and numerical modeling with experimental observations. The first part focuses on the analytical model. The model takes into account the nonlinearity derived from large amplitude vibration and inertia. The second part deals with the experimental test, where the specimen and the data acquisition are defined. Then, the nonlinearity of the acquired data is determined by the fitting time history (FTH) technique. The third part deals with the finite element model. Finally, the results obtained by the analytical method, the experimental method, and the numerical method are compared between each other.

Hybridity in Asian Christian Discourse: Critical Issues from Asian Christian Experience

2018 ◽  
Vol 1 (2) ◽  
pp. 250-268
Author(s):  
Jose Mario C. Francisco
Keyword(s):  
Cultural Studies ◽  
Crossing Over ◽  
Religious Traditions ◽  
The Third ◽  
Theological Discourse ◽  
Critical Issues ◽  
Christian Discourse

This study explores the crossing over of the concept of hybridity from cultural studies to theological discourse with particular reference to Asian Christianity. The first section focuses on the emergence and currency of the concept in relation to different historical waves of globalization, and the second, on the concept of hybridity itself and its conceptual characteristics. The third discusses how hybridity sheds light on Asian Christianity’s encounter with cultures and religious traditions. It further uncovers critical issues involving the inherent struggle for and within inculturation and the nature of Christianity’s borders. Asian Christian theological discourse on these issues underscores nuances in religious hybridity that support transformative praxis and which may be overlooked in other contexts.

Septum formation in Aspergillus nidulans

1995 ◽  
Vol 73 (S1) ◽  
pp. 396-399 ◽  
Author(s):  
Michelle Momany ◽  
Jennifer L. Morrell ◽  
Steven D. Harris ◽  
John E. Hamer
Keyword(s):  
Aspergillus Nidulans ◽  
Antibody Production ◽  
Nuclear Division ◽  
Temperature Sensitive ◽  
Cellular Processes ◽  
The Third ◽  
Septum Formation ◽  
Chromosome Transmission ◽  
Insight Into

We are investigating septation in Aspergillus nidulans. We have shown that septum formation is dependent on the third nuclear division and actin is involved in this process. We have also characterized nine temperature-sensitive septation (sep) mutants. On the basis of our analysis we have divided these mutants into three phenotypic classes. We are uncovering the order of events in the septation pathway by analysis of double mutants constructed with different pairs of sep mutants. The sepB gene has been cloned and sequenced. Homology with the Saccharomyces cerevisiae CTF4 gene and the phenotype of the sepB mutant support a role in monitoring the fidelity of chromosome transmission. We are also investigating the role of the asp genes (Aspergillus septins). Three asp genes were identified by homology with the S. cerevisiae septins. aspB has been cloned, sequenced, and fused to a biotinylated tag for antibody production. Antibody production and localization studies are now underway. Because septation requires the integration of several cellular processes, our studies should give insight into the cell cycle, cell wall biosnythesis and development of A. nidulans. Key words: septation, cytokinesis, Aspergillus nidulans.

scholarly journals THE ORGANIZATION OF GENETIC VARIATION FOR RECOMBINATION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 525-547
Author(s):  
Lisa D Brooks ◽  
R William Marks
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Natural Population ◽  
Small Region ◽  
Crossing Over ◽  
Fine Scale ◽  
Response To Selection ◽  
Natural Genetic Variation ◽  
The Third ◽  
Scale Response

ABSTRACT The amount and form of natural genetic variation for recombination were studied in six lines for which second chromosomes were extracted from a natural population of Drosophila melanogaster. Multiply marked second, Χ and third chromosomes were used to score recombination. Recombination in the second chromosomes varied in both amount and distribution. These second chromosomes caused variation in the amount and distribution of crossing over in the Χ chromosome and also caused variation in the amount, but not the distribution, of crossing over in the third chromosome. The total amount of crossing over on a chromosome varied by 12-14%. One small region varied twofold; other regions varied by 16-38%. Lines with less crossing over on one chromosome generally had less crossing over on other chromosomes, the opposite of the standard interchromosomal effect. These results show that modifiers of recombination can affect more than one chromosome, and that the variation exists for fine-scale response to selection on recombination.

Use of Neurospora Spore killer strains to obtain centromere linkage data without dissecting asci

1986 ◽  
Vol 28 (6) ◽  
pp. 971-981 ◽  
Author(s):  
David D. Perkins ◽  
Namboori B. Raju ◽  
Virginia C. Pollard ◽  
Joseph L. Campbell ◽  
Adam M. Richman
Keyword(s):  
Meiotic Division ◽  
Nuclear Division ◽  
Linkage Data ◽  
Crossing Over ◽  
Tetrad Analysis ◽  
Marker Alleles ◽  
Spore Killer ◽  
Killer Gene

Use of a centromere-linked Spore killer gene Sk reduces manyfold the labor involved in obtaining tetrad data that would otherwise require ordered dissection of intact linear eight-spored asci. Heterozygous crosses are made for Spore killer (SkK × SkS) and for markers to be tested. In such crosses only SkK ascospores survive. The four viable (SkK) and four aborted (SkS) ascospores of each ascus are ejected from the perithecium as a physically disordered group. The four surviving SkK ascospores of individual asci are germinated and scored. SkK segregates from SkS at the first meiotic division. If both marker alleles are represented in the surviving products, they must therefore have segregated from one another at the second division. Four-spore (Fsp) genes have been used to eliminate one postmeiotic nuclear division, so that only two ascospores per ascus need to be scored. The Spore killer method has been useful for mapping closely linked genes in centromere regions, for identifying genes that are far out on chromosome arms, for obtaining information on meiotic crossing-over, and for comparing linkages in different species.Key words: tetrad analysis, centromere mapping, Spore killer, Neurospora.

scholarly journals CYTOGENETIC BEHAVIOR OF SPORE KILLER GENES IN NEUROSPORA

Genetics ◽  
1979 ◽  
Vol 93 (3) ◽  
pp. 607-623
Author(s):  
Namboori B Raju
Keyword(s):  
Light Microscopy ◽  
Nuclear Division ◽  
The Third ◽  
Ascospore Development ◽  
Single Nucleus ◽  
Spore Killer

ABSTRACT Crosses heterozygous and homozygous for Sk–1, Sk–2 and Sk–3 were examined by light microscopy. All three Spore killers behave similarly. In heterozygoua killer x sensitive crosses, meiosis and ascospore development are normal until after the second postmeiotic mitosis when four of the eight ascospores in each ascus stop developing and degenerate. The four surviving ascospores carry the killer. Death of sensitives thus occurs only after killer and sensitive alleles, SkK and SkS, have segregated into separate ascospores. Homozygous killer x killer crosses do not show such a pattern of degeneration. Either all ascospores are normal or, if some fail to mature, they do not resemble the degenerating sensitive ascospores in heterozygous asci.——With Sk–2, it was shown that SkS nuclei do not abort when both SkK and SkS are present in the same ascospore. Mutants affecting ascus development were used to obtain large ascospores enclosing both SkK and SkS meiotic products in a common cytoplasm. SkS nuclei do not then undergo the degeneration that would be seen if they werc sequestered into separate ascospores, and viable SkS progeny are recovered in undiminished numbers when the mixed multinucleate large ascospores are germinated. In a four-spored mutant, where each ascospore encloses a single nucleus following meiosis, degeneration of SkS ascospores nevertheless occurs, even though the third nuclear division is omitted. Cycloheximide and temperature treatments do not affect: the expression of SkK.

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