Publications by authors named "Ruzanna Petrosyan"
Background: Cerebrovascular accident (CVA) is a major global contributor to death and disability. As part of its medical management, researchers have recognized the importance of promising neuroprotective strategies, where stem cell transplantation (SCT) is thought to confer advantages trophic and neuroprotective effects.
Aim: To evaluate the current state of research on SCT in patients with CVA, assess key trends and highlight literature gaps.
Among vertebrates, obligate parthenogenesis occurs exclusively in squamate reptiles. Premeiotic endoreplication in a small subset of developing oocytes has been documented as the mechanism of production of unreduced eggs in minutely explored obligate parthenogenetic lineages, namely in teiids and geckos. The situation in the lacertid genus has been discussed for decades.
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- Valentin's rock lizard is believed to be the parent species of several parthenogenetic rock lizard species, indicating complex evolutionary processes in their shared habitats.
- This lizard species is long-lived and exhibits a distinctive size difference between genders, with females being larger, which is atypical for its genus.
- They have adaptations for high-altitude living, such as larger eggs and early reproduction, and their population density can vary widely without being impacted by the presence of parthenogenic species.
According to the synthesis of 30 years of multidisciplinary studies, parthenogenetic species of rock lizards of genus were formed as a result of different combination patterns of interspecific hybridization of the four bisexual parental species: , , , and . In particular, and are considered as the parental species for the parthenogenetic species . Here for the first time, we present the result of comparative immunocytochemical study of primary spermatocyte nuclei spreads from the leptotene to diplotene stages of meiotic prophase I in two species: and .
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- Research investigates the fertility of triploid hybrids from natural hybridization of parthenogenetic and bisexual rock lizards, important for understanding their evolution.
- Karyotyping and immunocytochemistry analysis revealed a triploid hybrid with three chromosome sets, with chromosomal anomalies affecting synapsis and repair in meiosis.
- Despite the abnormalities, the study found that meiosis and spermatogenesis continued, resulting in numerous abnormal mature spermatids in the hybrid's testes.