Cytogenetics of Some New Guinean Dasyurids and Genome Evolution in the Dasyuridae (Marsupialia)

1989 ◽  
Vol 37 (5) ◽  
pp. 521 ◽  
Author(s):  
M Westerman ◽  
PA Woolley
Keyword(s):  
Genome Evolution ◽  
Y Chromosome ◽  
X Chromosome ◽  
Nuclear Dna ◽  
New Guinea ◽  
Size And Shape ◽  
Australian Species ◽  
Extant Species ◽  
Dna Values

Karyotypes have been obtained for ten species of New Guinean dasyurid marsupials. All species have 2n = 14 chromosomes which, except for variation in size and shape of the X chromosome, are similar in morphology, not only between species but also to Australian species. The Y chromosome of all species is punctiform. C- and G-banding procedures have been applied to eight of the species and show (1) there are no major differences between species in amounts of C-band heterochromatin, and (2) the G-band patterns of the autosomes were virtually identical. These findings suggest that there have been no major karyotypic changes accompanying speciation of dasyurids in New Guinea. Since the G-banded karyotypes are also virtually identical to those reported for Australian dasyurids it would appear that this 2n = 14 karyotype probably represents the ancestral dasyurid form which can be derived as a result of a few inversions from an ancestral marsupial karyotype. These changes must have occurred very early in the dasyurid radiation as the) are found in all extant species and genera examined. However, virtually identical G-banded karyotypes may mask major differences in nuclear DNA values.

The Chromosomes of Six Species of the Drosophila lativittata Complex

1984 ◽  
Vol 32 (1) ◽  
pp. 43 ◽  
Author(s):  
IR Bock
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Sexual Isolation ◽  
Species Group ◽  
Interspecific Crosses ◽  
Banding Patterns ◽  
Australian Species

Metaphase and polytene karyotypes were investigated in six Australian species of the Drosophila (Scaptodrosophila) coracina species-group: lativittata, enigma, specensis, howensis, nitidithorax and novamaculosa. The male metaphase karyotype of each species consists of three pairs of telocentric; one pair of metacentric and one pair of small heterochromatic chromosomes, plus a large acrocentric X-chromosome and a smaller acrocentric Y-chromosome. The polytene karyotype of each species consists of six arms and a small chromocentre. No inversion polymorphisms were found in the two species (lativittata and enigma) investigated for this phenomenon. Interspecific crosses obtained between enigma and howensis and between lativittata and nitidithorax revealed that the former species (between which sexual isolation is incomplete) are entirely homosequential, and differences in polytene banding patterns between the latter species are very slight. Photographic comparisons otherwise revealed that the banding sequences of all six species are substantially identical.

Evolution of a Y Chromosome from an X Chromosome

2019 ◽  
Author(s):  
Roberta Bergero ◽  
Jim Gardner ◽  
Deborah Charlesworth
Keyword(s):  
Y Chromosome ◽  
X Chromosome

Quantitative nuclear DNA differences associated with genome evolution in Guizotia (Compositae)

Genetica ◽  
1992 ◽  
Vol 85 (3) ◽  
pp. 241-247 ◽  
Author(s):  
S. C. Hiremath ◽  
H. N. Murthy ◽  
S. S. Salimath
Keyword(s):  
Genome Evolution ◽  
Nuclear Dna

scholarly journals Recombination between the mouse Y chromosome short arm and an additional Y short arm-derived chromosomal segment attached distal to the X chromosome PAR

Chromosoma ◽  
2015 ◽  
Vol 125 (2) ◽  
pp. 177-188
Author(s):  
Fanny Decarpentrie ◽  
Obah A. Ojarikre ◽  
Michael J. Mitchell ◽  
Paul S. Burgoyne
Keyword(s):  
Y Chromosome ◽  
X Chromosome ◽  
Chromosomal Segment

Roles of Anti-Müllerian hormone (Amh) and its duplicates in sex determination and germ cell proliferation of Nile tilapia

Genetics ◽  
2021 ◽  
Author(s):  
Xingyong Liu ◽  
Shengfei Dai ◽  
Jiahong Wu ◽  
Xueyan Wei ◽  
Xin Zhou ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Sex Determination ◽  
Germ Cell ◽  
Y Chromosome ◽  
X Chromosome ◽  
Nile Tilapia ◽  
Critical Period ◽  
Sex Reversal ◽  
Homozygous Mutation ◽  
Germ Cell Proliferation

Abstract Duplicates of amh are crucial for fish sex determination and differentiation. In Nile tilapia, unlike in other teleosts, amh is located on X chromosome. The Y chromosome amh (amh△-y) is mutated with 5 bp insertion and 233 bp deletion in the coding sequence, and tandem duplicate of amh on Y chromosome (amhy) has been identified as the sex determiner. However, the expression of amh, amh△-y and amhy, their roles in germ cell proliferation and the molecular mechanism of how amhy determines sex is still unclear. In this study, expression and functions of each duplicate were analyzed. Sex reversal occurred only when amhy was mutated as revealed by single, double and triple mutation of the three duplicates in XY fish. Homozygous mutation of amhy in YY fish also resulted in sex reversal. Earlier and higher expression of amhy/Amhy was observed in XY gonads compared with amh/Amh during sex determination. Amhy could inhibit the transcription of cyp19a1a through Amhr2/Smads signaling. Loss of cyp19a1a rescued the sex reversal phenotype in XY fish with amhy mutation. Interestingly, mutation of both amh and amhy in XY fish or homozygous mutation of amhy in YY fish resulted in infertile females with significantly increased germ cell proliferation. Taken together, these results indicated that up-regulation of amhy during the critical period of sex determination makes it the sex-determining gene, and it functions through repressing cyp19a1a expression via Amhr2/Smads signaling pathway. Amh retained its function in controlling germ cell proliferation as reported in other teleosts, while amh△-y was nonfunctionalized.

Chromosomal Mechanisms in the Evolution of Artiodactyls

Paleobiology ◽  
1975 ◽  
Vol 1 (2) ◽  
pp. 175-188 ◽  
Author(s):  
Neil B. Todd
Keyword(s):  
X Chromosome ◽  
Fossil Record ◽  
Diploid Number ◽  
Evolutionary Sequence ◽  
Extant Species ◽  
Adaptive Radiations ◽  
The Times

Evidence is presented that primitive artiodactyls had a diploid number of 14. The higher diploid numbers of most living artiodactyls are interpreted as resulting from karyotypic fissioning at the times of past adaptive radiations. The fossil record appears to support this contention.An evolutionary sequence of unusual X chromosome transformations has been deduced from the differences that exist among extant species. From these, and from interrelationships of karyotypes, certain phylogenetic revisions are suggested.

Clues from other animals and theoretical considerations

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 3-4
Author(s):  
Anne McLaren
Keyword(s):  
Sex Determination ◽  
Genetic Control ◽  
Y Chromosome ◽  
X Chromosome ◽  
X Chromosomes ◽  
The Third ◽  
Mouse Species ◽  
Primary Male ◽  
Theoretical Considerations ◽  
State Of Activity

In the first two papers of this volume, the genetic control of sex determination in Caenorhabditis and Drosophila is reviewed by Hodgkin and by Nöthiger & Steinmarin-Zwicky, respectively. Sex determination in both cases depends on the ratio of X chromosomes to autosomes, which acts as a signal to a cascade of règulatory genes located either on autosomes or on the X chromosome. The state of activity of the last gene in the sequence determines phenotypic sex. In the third paper, Erickson & Tres describe the structure of the mouse Y chromosome and the polymorphisms that have been detected in different mouse species and strains. As in all mammals, the Y carries the primary male-determining locus; autosomal genes may also be involved in sex determination, but they must act down-stream from the Y-linked locus.

On the genus Diadocidia (Diptera, Sciaroidea, Diadocidiidae) in Australia

Zootaxa ◽  
2007 ◽  
Vol 1655 (1) ◽  
pp. 63-68
Author(s):  
MATHIAS JASCHHOF ◽  
CATRIN JASCHHOF
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Australian Species

The first two Australian species of the genus Diadocidia Ruthe, macrosetigera sp. n. and queenslandensis sp. n., are described from Queensland. Both species are assigned to the subgenus Adidocidia Laštovka & Matile. As structures of the male terminalia suggest, the two Australian species are only distantly related to one another, whereas queenslandensis shows definite affinities to D. (A.) papua Ševčík from Papua New Guinea.

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