Hello po, ma’am! Thank you very much po and happy holidays po. Below is our group's response po to your queries regarding our topic po:
1. Meroblastic cleavage is a kind of convergent evolution because several groups that perform this process have differences in their early development. These groups include Myxini, Chondrichthyes, Teleostei, Actinistia, and Amniota.
2. Various factors govern patterns of embryonic cleavage: embryo size, yolk disposition, oocyte polarity, localization of molecular cues, and cell shape (Hasley et al., 2017). Cleavage involves intense cellular assembly. Under conditions such as DNA damage, and affected spermatozoal chromatin packaging, centriolar and mitotic spindle integrity, and plasma membrane integrity, abnormal early cleavage may result (Burruel et al., 2014). Chromosome segregation errors that arise at the beginning of mammalian life can lead to aneuploidy (or the condition of having an abnormal number of chromosomes) and failure to develop normally to the later stages. Such aberrations may lead to spontaneous abortions and birth defects (Shcneider & Ellenberg, 2019).
3. Currently, there is limited information regarding the existence of a solution to establishing breeding colonies in the lab, particularly because reptiles are not really as commonly used as mice and zebrafish in research. However, we did find several connected articles which might also help in updating the status of the study of reptiles in the laboratory. The first study was done by Sheverdyukova and Merzlikin (2021) which tackled the difficulty of observing the early developmental stages of an oviparous grass snake by performing a cesarean section to obtain the egg from gravid females caught in the wild. This method is deemed a valuable tool since it can preserve the life and reproductive ability of the snake, especially in rare species. Another study was by Lima et al. (2019) which used captive-bred populations of green iguanas in a scientific breeding at the Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP—Rio Claro). The study did not go into detail about how these breeding colonies were established but did mention that the laboratory/university underwent various procedures and certification to proceed with the collection of the embryos and to be duly licensed by ICMBIO/IBAMA—No. 973766 to breed captive iguanas. This means that, although minimal, there exist certain laboratories where the breeding of reptiles is being undertaken with full ethical considerations, thus, the study of the development of reptiles can further be advanced.
References:
Burruel, V., Klooster, K., Barker, C. M., Pera, R. R., & Meyers, S. (2014). Abnormal early cleavage events
predict early embryo demise: sperm oxidative stress and early abnormal cleavage. Scientific reports, 4, 6598. https://doi.org/10.1038/srep06598.
Lima, F. C., Py‐Daniel, T. R., Sartori, M. R., Abe, A. S., Santos, O. P. D., Freitas, L. M., Pereira, K. F., & Sebben, A. (2019). Developmental staging table of the green iguana. Acta zoológica, 100(3), 232-244.
Schneider, I., & Ellenberg, J. (2019). Mysteries in embryonic development: How can errors arise so
frequently at the beginning of mammalian life?. PLOS Biology 17(3): e3000173. https://doi.org/10.1371/journal.pbio.3000173.
Sheverdyukova, H., & Merzlikin, I. R. (2021). Obtaining Oviparous Grass Snake Natrix natrix (Serpentes, Colubridae), embryos at Early Developmental Stages by Caesarean Section. Zoodiversity, 55(3), 217-224.
