Mer22-related sequence elements form pericentric repetitive DNA families in primates

We describe a novel repetitive DNA element isolated from three primate species belonging to the family Cercopithecidae. The unusually long 2.6-kb repeat unit of this DNA element is present in high copy number in the pericentromeric region of one pair of chromosomes in both baboon and macaque, forming chromosome-specific satellite-like DNA families. Besides these two very closely related species, the novel DNA element was also detected in the more distantly related African green monkey. However, the copy number of the repeat unit in this species is significantly lower than in macaque and baboon. Sequence analysis revealed that the repeat units of the new repetitive element show similarity to the human MER22 repeat and the Y chromosome-specific TTY2 element, which also exhibits retroelement-like features. Database searches indicate that tandemly arranged MER22-related DNA sequences can also be found in human, raising the possibility that these DNA elements may correspond to a novel primate-specific repetitive DNA group. Recent studies indicate that chromosome-specific pericentric repetitive elements, besides their potential involvement in centromere function, also facilitate homolog recognition during meiosis. In addition, rapid expansion of retroelements in the pericentric regions of chromosomes during interspecific hybridization has been described. In light of these data, we hypothesize that the novel repetitive element described here might have been involved in the speciation of the family Cercopithecidae.     

Designing of Nucleocapsid Protein Based Novel Multi-epitope Vaccine Against SARS-COV-2 Using Immunoinformatics Approach

International Journal of Peptide Research and Therapeutics - The COVID-19 disease is caused by SARS-CoV-2 and spreading rapidly worldwide with extremely high infection rate. Since effective and...     

Cytogenetic and fertility studies of a rheboon, rhesus macaque (Macaca mulatta) x baboon (Papio hamadryas) cross: further support for a single karyotype nomenclature.

Historically, two different numbering systems have been used to describe the baboon and macaque karyotypes. However, G-banding studies and, more recently, fluorescence in situ hybridization results have shown that the two karyotypes are virtually identical. To confirm this hypothesis, cytogenetic analysis of an unusual animal, a rheboon, was undertaken. The rheboon reported here, an 18-year-old male, is the only long-term survivor of 26 pregnancies resulting from matings between female baboons (Papio hamadryas) and male rhesus macaques (Macaca mulatta). A G-banded karyotype was prepared from the rheboon and compared with the karyotypes of the two parental species. Spectral karyotyping (SKY) was carried out on the rheboon chromosomes, and the results were compared with SKY studies reported for the baboon and with CISS (chromosome in situ suppression) studies in the rhesus macaque. No differences were detected in any of the rheboon's pairs of autosomes, reinforcing the apparent identity of the two parental karyotypes. Based on these results, we argue that a single karyotyping system should be adopted for the two species. Fertility studies were initiated to determine if the rheboon is sterile, as are most hybrid animals. Two semen ejaculates were devoid of sperm. A testicular biopsy revealed hypoplasia of the seminiferous tubules with few Leydig cells and large lumena. Meiotic arrest occurred during meiosis I, resulting in absence of mature spermatozoa. Thus, the testicular and meiotic findings in the rheboon were similar to those observed in other hybrids, even though the parental karyotypes appear identical.