Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 25

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  methylation
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Methylation of RNA and proteins is one of a broad spectrum of post-trans- criptional/translational mechanisms of gene expression regulation. Its functional signification is only beginning to be understood. A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the methylation effect on biomolecules interaction is presented. Two RNA-peptide systems were chosen for the study. The first one consists of a 17-nucleotide analogue (+27-+43) of the yeast tRNA Phe anticodon stem and loop domain (ASL Phe) containing three of the five natu­rally occurring modifications (2'-O-methylcytidine (Cm32), 2'-O-methylguanine (Gm34) and 5-methylcytidine (m5 C40)) (ASL Phe -Cm32,Gm34,m5 C40) and a 15-amino-acid peptide (named tF 2: Ser1 -Ile-Ser-Pro-Trp5 -Gly-Phe-Ser-Gly-Leu10 -Leu- Arg-Trp-Ser-Tyr15 ) selected from a random phage display library (RPL). A pep- tide-concentration-dependent formation of an RNA-peptide complex was clearly ob­servable by CEMSA. In the presence of the peptide the capillary electrophoresis (CE) peak for triply methylated ASL Phe shifted from 18.16 to 20.90 min. Formation of the complex was not observed when an unmethylated version of ASL Phe was used. The second system studied consisted of the (+18)-(+44) fragment of the trans-activation response element of human immunodeficiency virus type 1 (TAR RNA HIV-1) and a 9-amino-acid peptide of the trans-activator of transcription protein (Tat HIV-1) Tat(49–57)-NH2 (named Tat1: Arg49-Lys-Lys-Arg52-Arg-Gln-Arg-Arg- Arg57-NH2). In the presence of Tat(49–57)-NH2 a significant shift of migration time of TAR from 18.66 min to 20.12 min was observed. Methylation of a residue Arg52->Arg(Me)2, crucial for TAR binding, strongly disrupted formation of the complex. Only at a high micromolar peptide concentration a poorly shaped, broad peak of the complex was observed. CE was found to be an efficient and sensitive method for the analysis of methylation effects on interaction of biomolecules.
6
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Sperm epigenetic profile and risk of cancer

75%
Introduction and objective. The integrity, stability and composition of sperm chromatin are of great importance in the fertilizing potential of male gametes and their capacity to support normal embryonic development. In this study, the author presents the current state of knowledge about the sperm epigenetic profile and risk of cancer. Abbreviated description of the state of knowledge. The obtaining of pregnancy and the state of health of the baby depends on the quality of the genetic material of both the female and the male. Health behaviours and environmental factors directly affect the quality of sperm, as well as the human egg cell and, consequently, on the reproductive capabilities, the course of pregnancy and the state of the newborn. There exist two thoroughly investigated epigenetic modifications: DNA methylation and histone modifications. The process of DNA methylation can be also a fundamental factor contributing to the development of cancer, where epigenotype undergoes significant modifications. When considering numerous DNA aberrations in the male gamete, the most commonly encountered is DNA fragmentation, particularly in infertile subjects. Surprisingly, an intracytoplasmatic sperm injection study of mice oocytes, using spermatozoa with a high DNA Fragmentation Index (DFI), revealed that a considerable percentage of adults born as a result of this method, showed a significant increase in the incidence of abnormal behavioural tests, malformations, cancer and signs of premature aging. Summary. The issue of assisted procreation raises the need to look for an appropriate treatment for males with sperm chromatin abnormalities. As a result, the fight against smoking addiction becomes the obvious necessity. Moreover, the reasonable solution nowadays seems to be supplementation with micronutrients and folic acid. It has been proved that the process of DNA fragmentation is a phenomenon that intensifies over time. Therefore, there should be a pursuance for, as close as possible, to the moment of ejaculation, application of semen to reproductive techniques. Finally, epigenetic changes are suspected of being one of the factors responsible for the deterioration of male sperm parameters observed in recent decades.
The C-terminal end of the fragile X mental retardation protein contains a stretch of amino acid residues that are enriched in arginine and glycine. Recent studies using recombinant FMRPs have demonstrated that this region participates in RNA binding in vitro, with calculated KdS ranging from 1-10 nM depending on the RNA. It is known that other arginine glycine-rich proteins are subject to site-specific methylation by protein arginine methyltransferases (PRMTs) that are particularly abundant in most cells. We have demonstrated that the interaction of homoribopolymer mimetic RNAs with human FMRP (hFMRP) made in PRMT-containing cell-free lysates is more sensitive to increasing salt concentrations than recombinant hFMRP expressed in bacteria. We have also shown that blocking methylation with adenosine-2', 3'-dialdehyde (AdOx) alters homoribopolymer binding and hFMRP target mRNA binding; both increases and decreases are observed as a function of methylation. These data suggest that changes in PRMT activity that occur during development, or arise via signal transduction may be a means of regulating the binding of hFMRP to mRNA in vivo.
The purpose of the present review is to conduct a detailed description of mercury cycling and accumulation within the freshwater ecosystem and to identify natural chemical and biological processes which affect mercury availability in the aquatic environment.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.