Constitutive heterochromatin distribution in pig (Sus scrofa) chromosomes

Caryologia ◽  
1998 ◽  
Vol 51 (1) ◽  
pp. 65-72 ◽  
Author(s):  
G.P. Di Meo ◽  
A. Perucatti ◽  
L. Ferrara ◽  
M. Palazzo ◽  
D. Matassino ◽  
...  
2021 ◽  
pp. 1-10
Author(s):  
Nadezhda G. Ivanova ◽  
Dmitrii Ostromyshenskii ◽  
Olga Podgornaya

Constitutive heterochromatin is the most mysterious part of the eukaryotic genome. It forms vital chromosome regions such as the centromeric and the pericentromeric ones. The main component of heterochromatic regions are tandem repeats (TR), and their specific organization complicates assembly, annotation, and mapping of these regions. Unannotated and unmapped TR arrays are still present in database contigs. In this study, we used a set of TR in the genomes of the pig (Sus scrofa) and the Chinese hamster (Cricetulus griseus) identified with the help of bioinformatics techniques and determined the specificity of the designed probes. The signal of the 4 pig TR probes in spermatogenic cells was often ring-shaped, especially in primary spermatocytes. The rings were located in the regions relatively weakly stained with DAPI. The unique assembly of the centromeric region was traced using the hamster meiotic chromosomes. The probe specific to chromosome 5 was used. Two signals, arranged as rings, were seen at the pachytene stage, similar to those in the pig spermatogenic cells. In the spermatogenic cells of both pig and hamster, the rings appeared on the chromosomes with pericentromeric TR probes. Our observations support the loop model of the centromeric region, the size of the loops being about 50 kb.


2019 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Abyt Ibraimov

In many animals, including us, the genetic sex is determined at fertilization by sex chromosomes. Seemingly, the sex determination (SD) in human and animals is determined by the amount of constitutive heterochromatin on Y chromosome via cell thermoregulation. It is assumed the medulla and cortex tissue cells in the undifferentiated embryonic gonads (UEG) differ in vulnerability to the increase of the intracellular temperature. If the amount of the Y chromosome constitutive heterochromatin is enough for efficient elimination of heat difference between the nucleus and cytoplasm in rapidly growing UEG cells the medulla tissue survives. Otherwise it doomed to degeneration and a cortex tissue will remain in the UEG. Regardless of whether our assumption is true or not, it remains an open question why on Y chromosome there is a large constitutive heterochromatin block? What is its biological meaning? Does it relate to sex determination, sex differentiation and development of secondary sexual characteristics? If so, what is its mechanism: chemical or physical? There is no scientifically sound answer to these questions.


2019 ◽  
Author(s):  
Sebasti�n A. Ballari ◽  
Sebasti�n Cirignoli ◽  
Marina Winter ◽  
Mar�a Fernanda Cuevas ◽  
Mariano L. Merino ◽  
...  
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