scholarly journals Evolutionary implications of meiotic Chromosome Behavior, Reproductive Biology, and Hybridization in 6X and 9X Cytotypes of Andropogon gerardii (Poaceae)

1997 ◽  
Vol 84 (2) ◽  
pp. 201-207 ◽  
Author(s):  
Guillermo A. Norrmann ◽  
Camilo L. Quarín ◽  
Kathleen H. Keeler
Keyword(s):  
Reproductive Biology ◽  
Meiotic Chromosome ◽  
Andropogon Gerardii ◽  
Chromosome Behavior

Meiotic chromosome behavior of Haworthia limifolia

2016 ◽  
Vol 5 (03) ◽  
pp. 4902
Author(s):  
Afrin Nazli ◽  
Kamini Kumar*
Keyword(s):  
Genetic Recombination ◽  
Meiotic Chromosome ◽  
Pollen Sterility ◽  
Meiotic Abnormalities ◽  
Chromosome Behavior ◽  
The Family ◽  
Medicinal Properties ◽  
Fruit Formation ◽  
Meiosis I ◽  
Chromosomal Behaviour

Haworthia limifolia is a xerophytic plant belonging to the family Liliaceae and is indigenous to Africa. It is use extensively for its medicinal properties like antibacterial, antifungal properties and used for the treatment of sores, superficial burns, as a blood purifier and to promote pregnancy in women and cattles. In present investigation chromosomal behaviour of H. limifolia in meiosis was studied. In diplotene stage chiasmata was observed showing the possibilities of genetic recombination. Chromosome clumps were observed in diakinesis indicating sticky nature of chromosomes. Meiotic abnormalities like stickiness, precocious movement, formation of bridges and laggards were also reported in both meiosis I and II. A fairly high percentage of pollen sterility that is 73.41% was recorded resulting in failure of fruit formation. This plant could be designated as facultative apomict (Swanson, 1957) as the only means of reproduction found was asexual or vegetative.

Intergeneric hybrids of Hordeum vulgare with Agropyron caninum and A. dasystachyum

1985 ◽  
Vol 27 (4) ◽  
pp. 387-392 ◽  
Author(s):  
George Fedak
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Spindle Fibre ◽  
Chromosome Behavior ◽  
Paternal Parent ◽  
Agropyron Caninum

Hybrids were obtained by pollinating Hordeum vulgare cv. Betzes with Agropyron caninum (4x) and A. dasystachyum (4x) at frequencies of 1.4 and 6.1% of pollinated florets, respectively. The hybrids were sterile and phenotypically resembled the paternal parent, except for floret structure which was intermediate between the parental types. Chromosome pairing at meiosis was very low and thus provided no indication of homoeology between parental genomes. Abnormal meiotic chromosome behavior in meiocytes that occurred in sectors on the 'Betzes' × A. dasystachyum hybrid was attributed to abnormal spindle fibre function.Key words: intergeneric hybrids, Hordeum vulgare, Agropyron caninum, Agropyron dasystachyum.

Mode of reproduction and meiotic chromosome behavior in Acroceras macrum

Crop Science ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 330-344
Author(s):  
Silvana C. Ferrari Usandizaga ◽  
Eric J. Martínez ◽  
Mara Schedler ◽  
Ana I. Honfi ◽  
Carlos A. Acuña
Keyword(s):  
Meiotic Chromosome ◽  
Chromosome Behavior ◽  
Mode Of Reproduction

Reproductive and Genetic-Studies With a Laboratory Colony of the Dasyurid Marsupial Sminthopsis-Crassicaudata

1989 ◽  
Vol 37 (3) ◽  
pp. 207 ◽  
Author(s):  
JH Bennett ◽  
WG Breed ◽  
DL Hayman ◽  
RM Hope
Keyword(s):  
Reproductive Biology ◽  
Meiotic Chromosome ◽  
Litter Production ◽  
Genetic Studies ◽  
Adult Weight ◽  
Sminthopsis Crassicaudata ◽  
Laboratory Colony ◽  
Marked Disparity ◽  
Marsupial Species ◽  
High Level

The fat-tailed dunnart, Sminthopsis crassicaudata, is a small insectivorous dasyurid (adult weight about 16 g) widely distributed in Australia. A laboratory colony of this marsupial, which has been built up over many years, is providing material for studies of dasyurid reproductive biology and genetics. In the area of reproductive biology, we have found a marked disparity in the age of maturation between the two sexes, and we are currently studying certain aspects of spermatogenesis, sperm transport, fertilisation and early embryonic development. Genetical studies have revealed large differences between the sexes in autosomal linkage values and meiotic chromosome behaviour. In females, we have observed very limited intrachromosomal recombination and this is reflected in the distal localisation of chiasmata on the autosomes. Extreme localisation of chiasmata has not hitherto been found in a mammal, and it will be interesting to see how widely it occurs in other marsupial species. The genetical and cytological findings lead to a number of predictions that are being tested in further experimental work with the colony. Although we have been able to raise litter production to a high level, the very variable and unpredictable nature of male reproductive performance currently limits the wider use of the S. crassicaudata colony. It is clear, however, that this dasyurid has the potential to become a very useful laboratory marsupial and that it will be especially valuable for comparative biomedical studies.

Bromus pictus of the B. setifolius complex (section Pnigma): numerical taxonomy and chromosome evidence for species rank

1990 ◽  
Vol 68 (11) ◽  
pp. 2493-2500 ◽  
Author(s):  
C. A. Naranjo ◽  
F. H. Arias ◽  
F. E. Gil ◽  
A. Soriano
Keyword(s):  
Breeding System ◽  
Numerical Taxonomy ◽  
Meiotic Chromosome ◽  
The Other ◽  
Genome Length ◽  
Chromosome Behavior ◽  
Banding Patterns ◽  
C Banding ◽  
Basic Genome ◽  
Components Analysis

Two biotic sympatric taxa of the Bromus setifolius complex, which are presently considered as varieties, were studied using cytological and numerical taxonomy methods. The numerical taxonomy analysis (cluster and principal components analysis) based on 35 characters showed the existence of two phenetically significant groups. One is formed by individuals that correspond to B. setifolius Presl. and the other by individuals with the characters of Bromus pictus Hook. All plants of B. setifolius had 2n = 4x = 28, and all the B. pictus individuals had 2n = 10x = 70. Other cytological differences between the two taxa were found, e.g., karyotype formulae, type of satellites, basic genome length, asymmetry, C-banding patterns, and meiotic chromosome behavior. Cytological differences, which parallel the constant morphological features exhibited by each taxa, justify specific status. Taking into acount other characters, such as perenniality, breeding system, and reproductive isolation barrier, the relationships and evolution of these taxa are discussed. Key words: Bromus setifolius, Bromus pictus, numerical taxonomy, karyotype, C-banding.

Sex-Specific Differences in Meiotic Chromosome Segregation Revealed by Dicentric Bridge Resolution in Mice

Genetics ◽  
2002 ◽  
Vol 162 (3) ◽  
pp. 1367-1379 ◽  
Author(s):  
Kara E Koehler ◽  
Elise A Millie ◽  
Jonathan P Cherry ◽  
Paul S Burgoyne ◽  
Edward P Evans ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Meiotic Recombination ◽  
Recombination Event ◽  
Meiotic Chromosome ◽  
Mammalian Species ◽  
Paracentric Inversion ◽  
Chromosome Behavior ◽  
Inverted Region ◽  
Dicentric Chromosomes ◽  
Chromatid Cohesion

Abstract The meiotic properties of paracentric inversion heterozygotes have been well studied in insects and plants, but not in mammalian species. In essence, a single meiotic recombination event within the inverted region results in the formation of a dicentric chromatid, which usually breaks or is stretched between the two daughter nuclei during the first meiotic anaphase. Here, we provide evidence that this is not the predominant mode of exchange resolution in female mice. In sharp contrast to previous observations in other organisms, we find that attempts to segregate the dicentric chromatid frequently result not in breakage, stretching, or loss, but instead in precocious separation of the sister centromeres of at least one homolog. This often further results in intact segregation of the dicentric into one of the meiotic products, where it can persist into the first few embryonic divisions. These novel observations point to an unusual mechanism for the processing of dicentric chromosomes in mammalian oogenesis. Furthermore, this mechanism is rare or nonexistent in mammalian spermatogenesis. Thus, our results provide additional evidence of sexual dimorphism in mammalian meiotic chromosome behavior; in “stressful” situations, meiotic sister chromatid cohesion is apparently handled differently in males than in females.

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