A LIGHT-MICROSCOPIC STUDY OF SOME TRANSLOCATIONS IN ASPERGILLUS NIDULANS

1978 ◽  
Vol 20 (3) ◽  
pp. 325-328 ◽  
Author(s):  
E. R. Boothroyd
Keyword(s):  
Aspergillus Nidulans ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Chromosome Analysis ◽  
Chromosome Behaviour ◽  
Structural Detail ◽  
Linkage Groups ◽  
Limited Evidence ◽  
Control Material ◽  
Reciprocal Translocations

A cytological investigation of the ascomycete, Aspergillus nidulans (Eidam) Winter, was undertaken to test the feasibility of using simple light-microscopial techniques to study chromosome aberrations for the correlation of chromosomes and linkage groups in this genetically well analysed fungus. Pachytene chromosome analysis was not possible, because the chromosomes are very small, do not spread well when squashed, and show very little structural detail. Some catenations were seen at first metaphase in translocation heterozygotes either as dense masses or, more rarely, as open rings. Lagging chromosomes were also seen at low frequency in both first and second anaphase and telophase in translocation but not in control material. The limited evidence from the study shows that meiotic chromosome behaviour in Aspergillus nidulans heterozygous for reciprocal translocations is probably similar to that in some higher organisms. However, the species is not suitable for detailed cytological analysis, at least by the techniques employed.

Cytogenetic analyses of intergeneric hybrids between barley and nine species of Elymus

Genome ◽  
2008 ◽  
Vol 51 (11) ◽  
pp. 897-904 ◽  
Author(s):  
N.-S. Kim ◽  
G. Fedak ◽  
F. Han ◽  
W. Cao
Keyword(s):  
Wild Species ◽  
Meiotic Chromosome ◽  
Abiotic Stress Tolerance ◽  
Chromosome Analysis ◽  
Intergeneric Hybrids ◽  
Biotic And Abiotic Stress ◽  
Crop Species ◽  
Barley Cultivars ◽  
Bivalent Formation ◽  
Gish Analysis

Wild species in the Triticeae tribe are very valuable resources for agronomic improvement in cereal crop species. Intergeneric hybrids were produced between several barley cultivars and perennial species in the genera Elymus , Thinopyrum , and Pseudoroegneria . Caryopsis formation and subsequent plantlet regeneration from embryo culture were variable depending on the hybrid combinations. Chromosome numbers and hybrid identity were confirmed by GISH analysis on the somatic cells of the hybrids. While the hybrids showed very robust vegetative growth and exceeded the parental spikes in size, their floral morphologies resembled that of the wild species. Meiotic chromosome analysis revealed that the bivalent formation frequency per cell ranged from 0.06 in Hordeum vulgare ‘Betzes’ × Elymus curvatus to 3.0 in Elymus humidus  × H. vulgare ‘Manley’. By GISH analysis on the meiocytes of the hybrid E. humidus × ‘Manley’, the frequency of autosyndetic bivalents exceeded the allosyndetic bivalent formation, which gave an insight into the genome constitution of E. humidus as an autoallohexploid species. Regardless of the low allosyndetic chromosome pairing between barley and E. humidus, this combination may be useful for further input, since E. humidus is known to carry many valuable genes for biotic and abiotic stress tolerance.

Meiotic chromosome behaviour in Cenchrus ciliaris

Bothalia ◽  
1998 ◽  
Vol 28 (1) ◽  
pp. 83-90 ◽  
Author(s):  
N. C. Visser ◽  
J. J. Spies
Keyword(s):  
Chromosome Number ◽  
Meiotic Chromosome ◽  
Basic Chromosome Number ◽  
Chromosome Behaviour ◽  
Meiotic Abnormalities ◽  
Single Specimen ◽  
Cenchrus Ciliaris ◽  
Basic Chromosome ◽  
Single Genome ◽  
Meiotic Irregularities

A basic chromosome number of x = 9 has been confirmed for Cenchrus ciliaris L. Polyploidy is common and levels vary from tetraploid to hexaploid. Aneuploidv is reported for a single specimen, where two chromosomes of a single genome were lost. Various meiotic irregularities were observed. The highest incidence of meiotic abnormalities was observed in the pentaploid specimens. This was attributed to their uneven polyploid level All specimens varied from segmental alloploid to alloploid.

Chromosome instability in wheat plants regenerated from suspension culture

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 627-629 ◽  
Author(s):  
George Fedak ◽  
K. C. Armstrong ◽  
R. J. Handyside
Keyword(s):  
Triticum Aestivum ◽  
Suspension Culture ◽  
Key Words ◽  
Chinese Spring ◽  
Meiotic Chromosome ◽  
Chromosome Instability ◽  
Wheat Chromosome ◽  
Chromosome Behaviour ◽  
Meiotic Configuration ◽  
Culture Suspension

Plants of Triticum aestivum cv. Chinese Spring were regenerated from 30 calli obtained from suspension cultures. All four plants showed abnormal meiotic chromosome behaviour relative to the control. The average meiotic configuration over all plants was 1.55 I + 18.16 II + 0.30 III + 0.82 IV. In addition, an isochromosome was frequently observed in cells of all plants, which was indicative of centromeric breaks. Key words: culture (suspension), wheat, chromosome instability.

scholarly journals Limited evidence for sardine and anchovy asynchrony: re-examining an old story

2020 ◽  
Vol 287 (1922) ◽  
pp. 20192781
Author(s):  
Margaret C. Siple ◽  
Timothy E. Essington ◽  
Lewis A. K. Barnett ◽  
Mark D. Scheuerell
Keyword(s):  
Time Series ◽  
Food Webs ◽  
Low Frequency ◽  
Single Species ◽  
The Other ◽  
Generalist Predators ◽  
Frequency Variation ◽  
Limited Evidence ◽  
Short Time Series ◽  
Short Time

Asynchronous fluctuations in abundance between species with similar ecological roles can stabilize food webs and support coexistence. Sardine ( Sardinops spp.) and anchovy ( Engraulis spp.) have long been used as an example of this pattern because low-frequency variation in catches of these species appears to occur out of phase, suggesting that fisheries and generalist predators could be buffered against shifts in productivity of a single species. Using landings data and biomass and recruitment estimates from five regions, we find that species do not have equivalent peak abundances, suggesting that high abundance in one species does not compensate for low abundance in the other. We find that globally there is a stronger pattern of asynchrony in landings compared to biomass, such that landings data have exaggerated the patterns of asynchrony. Finally, we show that power to detect decadal asynchrony is poor, requiring a time series more than twice the length of the period of fluctuation. These results indicate that it is unlikely that the dynamics of these two species are compensatory enough to buffer fisheries and predators from changes in abundance, and that the measurements of asynchrony have largely been a statistical artefact of using short time series and landings data to infer ecology.

Tetrasomic inheritance and chromosome pairing behaviour in the naturally occurring autotetraploid Heuchera grossulariifolia (Saxifragaceae)

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 655-659 ◽  
Author(s):  
Paul G. Wolf ◽  
Pamela S. Soltis ◽  
Douglas E. Soltis
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Small Chromosome ◽  
Tetrasomic Inheritance ◽  
Naturally Occurring ◽  
Chromatid Segregation ◽  
Marker Loci ◽  
Allozyme Loci ◽  
Pairing Behaviour

Inheritance patterns at four allozyme loci and chromosome pairing behaviour at diakinesis were examined in the naturally occurring autotetraploid Heuchera grossulariifolia. Segregation patterns for Tpi, Pgi, Pgm-2, and Lap deviated significantly from all possible disomic models. All patterns were consistent with tetrasomic inheritance of these marker loci. No chromatid segregation was detected electrophoretically. Meiotic chromosome configurations at diakinesis in 45 cells were compared with a previously published model to test for autopolyploid-like chromosome pairing. Using the observed chiasma frequencies, the frequency of quadrivalents was consistent with the expectations for an autotetraploid. We suggest that the low frequency of quadrivalents at diakinesis in Heuchera grossulariifolia is due to small chromosome size, which results in a low chiasma frequency.Key words: autopolyploidy, tetrasomic inheritance, chromosome pairing, isozyme genetics, Heuchera.

THE EFFECTS OF CYSTEAMINE AND AET Cl HCl ON THE INDUCTION OF MEIOTIC CHROMOSOME REARRANGEMENTS IN IRRADIATED MALE MICE

1974 ◽  
Vol 16 (1) ◽  
pp. 85-89 ◽  
Author(s):  
N. Savkovic ◽  
J. Pecevski
Keyword(s):  
Meiotic Chromosome ◽  
Chromosome Rearrangement ◽  
Meiotic Metaphase ◽  
Chromosomal Translocations ◽  
Whole Body ◽  
Reciprocal Translocations ◽  
Single Chromosome ◽  
X Ray ◽  
Chromosome Translocations ◽  
Chemical Agents

Two established chemical protective agents, β-mercaptoethylamine (cysteamine) and β-aminoethylisothiuronium (AET) Cl HCl were tested for their ability to induce chromosome translocations in totally irradiated mice with 600 R. The purpose of this investigation was to determine whether cysteamine and AET Cl HCl themselves induce reciprocal translocations and whether these chemical agents have an equally protective effect against X-ray-induced chromosomal translocations in the first meiotic metaphase. The incidence of translocations after whole-body irradiation with a 600 R was 9.07% in animals protected with cysteamine and irradiated; 3.68%; and in those protected with AET Cl HCl and irradiated with the same dose, 5.45%. Not a single chromosome rearrangement was recorded among the animals treated with cysteamine and AET without irradiation.

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