Postepy biochemii最新文献

The embryonic development of placental mammals takes place inside the mother’s womb, which requires the formation of appropriate supportive structures by both the mother’s organism and the developing embryo. The first stages of mammalian embryonic development, preceding implantation, are the period of differentiation of the first cell lineages – epiblast (which will give rise to the embryo proper), and extra-embryonic lineages: trophectoderm (responsible for implantation and formation of the placenta) and primitive endoderm (giving rise to the yolk sac). Their differentiation is necessary for further development, and is a common feature of the development of all placental mammals, but the timing and molecular mechanisms responsible for these processes differ between mammalian species.

Obtaining stable embryonic stem cells (ESC) from animals and humans opens up a wide spectrum of opportunities for science and regenerative medicine. The basic procedures necessary to obtain ESC are universal for all mammalian species. The challenge is to maintain species specific conditions required to support pluripotency characteristic for the pre-implantation embryo. To date, true ESC lines (stable in culture, pluripotent with high differentiation potential) have been obtained only for a limited number of species such as, mice, human and rats. The main obstacles arise from species specific differences, and thus different environmental requirements. However, in all cases, it is essential to maintain the activity of pluripotency related signalling pathways (WNT, MAPK/ERK and JAK/STAT3). The classical system dedicated to obtain mouse and human ESCs dependant on LIF (mice) of FGF (human) is not optimal. Currently, ESC derivation systems are based on chemical inhibitors that have the ability to interact with the above-mentioned pathways. This manuscript introduces the key factors important for understanding the nature of various types of stem cells (not only those of embryonic origin), and explains why there is no one way to obtain pluripotency, and why the definition of a stem cell is not universal.

The CHIMAERA has been known as a mythic, fire-breathing monster containing a lion’s head, goat’s body, and serpent’s tail. In modern biotechnology, this term has been used to describe organisms composed of cells derived from at least two zygotes and thus differing genetically. Experimentally produced chimaeras have become an extremely valuable tool in biomedical research, used, among others, for investigating the developmental potential of cells, the differentiation processes that occur during embryogenesis, as well as for studying gene function, modelling human diseases, and developing new therapies. The interspecific chimaeras are also a promising approach for the generation of human organs for transplantation and saving endangered species. This article summarizes the current state of knowledge on chimaeras formed with the contribution of pluripotent stem cells and discusses the prospects and threats related to their use in basic research and medicine.

Bisphenol A is a monomeric organic compound belonging to phenols. It is widely used in the production of resins, polycarbonates and plastics. Mass production of this compound contributed to its widespread presence in the environment, and thus - in the organisms of animals and humans. BPA belongs to xenoestrogens, synthetic compounds exerting an estrogen-like effect on cells. BPA can therefore disrupt the functioning of animal (including human) organisms. This article focuses on the impact of BPA on selected aspects of mammalian fertility. Recent literature data indicate that BPA disturbs several processes in oocytes and embryos, including epigenetic modifications, energy metabolism and spindle assembly, and as a result, decreases their developmental competence. We discuss the latest data on the influence of BPA on cellular processes taking place in oocytes and early embryos and describe molecular mechanisms responsible for this effect. We also discuss the significance of the results obtained from experiments conducted in vitro and/or on animal models in the context of BPA impact on fertility of women.

Developmental potential of oocytes and embryos is one of the key factors determining success in reproduction. In vitro produced embryos display reduced quality thus development of non-invasive approaches for quality assessment is a priority. Lipid metabolism belongs to fundamental mechanisms affecting reproductive processes and shaping the quality of gametes and embryos. The cytoplasm of oocytes and embryos contains specialized organelles for lipid storage (lipid droplets) whose number and size is species dependent. The growth and maturation of the oocyte/embryo is accompanied by a great fluctuation in lipid quality and quantity which in turn affects their quality and freezing suitability. There is a possibility to modify lipid parameters both in vivo and in vitro by supplementing fat to diet and culture media. The manuscript presents the current state of knowledge on lipid engagement in the process of quality acquirement by oocytes and embryos of two livestock species – cattle and pig.

The assisted reproduction techniques are an essential part of endangered species conservation programs. All wild felids are threatened with extinction, and the domestic cat is a good and easily available model for research on wild felids. The procedures used in cats and wild felids include artificial insemination, oocytes collection from female and sperm collection from male, in vitro maturation of oocytes, in vitro fertilization by IVF and ICSI, embryo culture, embryo transfer, cryopreservation of gametes and embryos. The effectiveness of individual procedures in cats and wild felids is often much lower than in humans, livestock or laboratory animals, but the success achieved so far confirms the need for further research.

In eukaryotic cells, DNA occurs mainly in a linear chromosomes. In addition, it can also take the form of circular molecules. Mitochondrial and chloroplast genomes are the most thoroughly studied circular DNAs. However, the repertoire of circular DNA in Eukarya is much broader. It also includes extrachromosomal circular DNA (eccDNA): circular forms of rDNA, telomeric circles, small polydisperse DNA, microDNA, and other types of eccDNA of nuclear origin. The occurrence of eccDNA has been confirmed in all organisms tested so far. Previous studies have shown that some eccDNAs are present at every stage of the cell cycle, while others appear and/or accumulate under specific circumstances. It has been proven that eccDNA accumulation accompanies severe genome destabilization caused by malignancies or stress conditions. Despite growing interest in eccDNA, they remain a poorly understood component of eukaryotic genomes. Still little is known about the mechanisms of their formation, evolution and biological functions.

Nucleoside boranephosphonates are nucleotide analogues in which one of the non-bridging oxygen atom of the phosphate part has been replaced by a borane group (-BH3). This modification imparts a wide spectrum of biological activity, e.g., activation of ribonuclease H, resistance to endo- and exonucleases, and their respective triphosphates are good substrates for DNA and RNA polymerases. Nucleoside boranephosphonate derivatives are used in antisense therapy, silencing gene expression using siRNA strategies, and as potential antiviral and anti-cancer prodrugs. Boranephosphonates find also applications as aptamers and as substrates in a new method of DNA sequencing. This review briefly presents potential biological applications of nucleoside boranephosphonates.