Muntjacs
Deer
RNA, Transfer, His
Scent Glands
RNA, Transfer, Ser
Chromosomes, Artificial, Bacterial
Effects of oleic acid, docosahexaenoic acid and eicosapentaenoic acid on background and genotoxin-induced frequencies of SCEs in Indian muntjac fibroblasts. (1/24)
Muntjac cells were cultured at 5 X 10(5) cells/10 cm Petri dish for 24 h prior to addition of fatty acids (50 microM) which were delivered to the cells complexed with 2% bovine serum albumin (fatty acid-free) and incubated for a further 24 h. Parallel dishes were processed for lipid extraction and GC analysis. This analysis showed highly significant (P < 0.01) uptake by the cells of each fatty acid. Genotoxins (75 microM hydrogen peroxide, 20 microM t-butylhydroperoxide and 2.4 microM mitomycin C) were added to the cells for 1 h prior to the end of the 24 h fatty acid incubation period. Control (no genotoxin or fatty acid) treatments were included. No difference was observed in background frequencies of SCEs between controls and fatty acid treatments, thus indicating that these fatty acids per se do not cause DNA damage. The cells incubated with the genotoxins showed increased (P < 0.05) frequencies of SCEs when compared with control frequencies. Cells incubated with genotoxins in the presence of fatty acids also showed significantly higher (P < 0.05) levels of SCEs when compared with control frequencies. When cells supplemented with genotoxins in the presence of fatty acids were compared with cells treated with genotoxins alone, higher levels of SCEs were observed in the former, suggesting that the fatty acids exacerbate DNA damage caused by these genotoxins. (+info)Megabase chromatin domains involved in DNA double-strand breaks in vivo. (2/24)
The loss of chromosomal integrity from DNA double-strand breaks introduced into mammalian cells by ionizing radiation results in the specific phosphorylation of histone H2AX on serine residue 139, yielding a specific modified form named gamma-H2AX. An antibody prepared to the unique region of human gamma-H2AX shows that H2AX homologues are phosphorylated not only in irradiated mammalian cells but also in irradiated cells from other species, including Xenopus laevis, Drosophila melanogaster, and Saccharomyces cerevisiae. The antibody reveals that gamma-H2AX appears as discrete nuclear foci within 1 min after exposure of cells to ionizing radiation. The numbers of these foci are comparable to the numbers of induced DNA double-strand breaks. When DNA double-strand breaks are introduced into specific partial nuclear volumes of cells by means of a pulsed microbeam laser, gamma-H2AX foci form at these sites. In mitotic cells from cultures exposed to nonlethal amounts of ionizing radiation, gamma-H2AX foci form band-like structures on chromosome arms and on the end of broken arms. These results offer direct visual confirmation that gamma-H2AX forms en masse at chromosomal sites of DNA double-strand breaks. The results further suggest the possible existence of units of higher order chromatin structure involved in monitoring DNA integrity. (+info)Reduced mobility of the alternate splicing factor (ASF) through the nucleoplasm and steady state speckle compartments. (3/24)
Compartmentalization of the nucleus is now recognized as an important level of regulation influencing specific nuclear processes. The mechanism of factor organization and the movement of factors in nuclear space have not been fully determined. Splicing factors, for example, have been shown to move in a directed manner as large intact structures from sites of concentration to sites of active transcription, but splicing factors are also thought to exist in a freely diffusible state. In this study, we examined the movement of a splicing factor, ASF, green fluorescent fusion protein (ASF-GFP) using time-lapse microscopy and the technique fluorescence recovery after photobleaching (FRAP). We find that ASF-GFP moves at rates up to 100 times slower than free diffusion when it is associated with speckles and, surprisingly, also when it is dispersed in the nucleoplasm. The mobility of ASF is consistent with frequent but transient interactions with relatively immobile nuclear binding sites. This mobility is slightly increased in the presence of an RNA polymerase II transcription inhibitor and the ASF molecules further enrich in speckles. We propose that the nonrandom organization of splicing factors reflects spatial differences in the concentration of relatively immobile binding sites. (+info)Molecular behavior in living mitotic cells of human centromere heterochromatin protein HPLalpha ectopically expressed as a fusion to red fluorescent protein. (4/24)
We constructed stable mammalian cell lines in which human heterochromatin protein HP1alpha and kinetochore protein CENP-A were differentially expressed as fusions to red (RFP-HP1) and green fluorescent proteins (GFP-CENP-A). Heterochromatin localization of RFP-HP1 was clearly shown in mouse and Indian muntjac cells. By preparing mitotic chromosome spreads, the inner centromere localization of RFP-HP1 was observed in human and Indian muntjac cells. To characterize its molecular behavior in living mitotic cells, time-lapse images of RFP-HP1 were obtained by computer-assisted image analyzing system, mainly with mouse cells. In G2 phase, a significant portion of RFP-HP1 diffused homogeneously in the nucleus and further dispersed into the cytoplasm soon after the nuclear membrane breakdown, while some remained in the centromeric region. Simultaneous observations with GFP-CENP-A in human cells showed that RFP-HP1 was located just between the sister kinetochores and then aligned to the spindle midzone. With the onset of anaphase, once it was released from there, it moved to the centromeres of segregating chromosomes or returned to the spindle equator. As cytokinesis proceeded, HP1alpha was predominantly found in the newly formed daughter nuclei and again displayed a heterochromatin-like distribution. These results suggested that, although the majority of HP1alpha diffuses into the cytoplasm, some populations are retained in the centromeric region and involved in the association and segregation of sister kinetochores during mitosis. (+info)Requirement of species-specific interactions for the activation of human gamma delta T cells by pamidronate. (5/24)
Human gammadelta T cells bearing Vgamma2Vdelta2-TCR recognize various kinds of small nonpeptide Ags, and activation of them by a nitrogen-containing bisphosphonate Ag, pamidronate, requires Ag presentation by cells other than gammadelta T cells, including many human tumor cells. Present results demonstrated that tumor cell lines of nonhuman origins pulsed with pamidronate failed to activate human gammadelta T cells without exception, whereas most if not all human tumor cell lines could do so. Gammadelta T cells formed stable conjugates with pamidronate-pulsed human tumor cells and both conjugate formation and gammadelta T cell activation were inhibited significantly by anti-LFA-1 mAb, suggesting the requirement of LFA-1-mediated interaction with APC for efficient gammadelta T cell activation. Consistently, ICAM-1(low) tumor cell lines pulsed with pamidronate induced no or only weak activation of gammadelta T cells, whereas similarly treated ICAM-1(high) cell lines could activate them. One of the two ICAM-1(low) tumor cell lines pulsed with pamidronate induced strong gammadelta T cell activation after ICAM-1 gene transfer. However, another ICAM-1(low) human cell line as well as murine tumor cell lines pulsed with pamidronate remained totally defective in gammadelta T cell activation even after expression of human ICAM-1. These results suggested that activation of human gammadelta T cells by nonpeptide Ags required species-specific interactions in addition to LFA-1/ICAM-1-mediated cell adhesion with APC. (+info)Asynchronous replication timing of telomeres at opposite arms of mammalian chromosomes. (6/24)
Telomeres are defining structural elements of all linear chromosomes, yet information concerning the timing of their replication in higher eukaryotes is surprisingly limited. We developed an approach that allowed a study of telomere replication patterns of specific mammalian chromosomes. In the Indian muntjac (Muntiacus muntjac), replication timing between respective telomeres of homologous chromosomes was highly coordinated, but no such synchrony was evident for p- and q-arm telomeres of the same chromosome. This finding contrasts with the coordinated timing of both ends of each chromosome in yeast. Also in contrast to yeast, where replication of all telomeres is confined to late S phase, we found specific telomeres in Indian muntjac chromosomes that replicated early in S and other telomeres that replicated later. Finally, replication timing of some but not all telomeres was influenced by telomere length. Knowledge of telomere replication timing represents a first step toward understanding the relationship between telomere replication and telomerase action. The approach, which we call replicative detargeting fluorescence in situ hybridization, is widely applicable to different species and genetic loci. (+info)ATM-dependent DNA damage-independent mitotic phosphorylation of H2AX in normally growing mammalian cells. (7/24)
H2AX is a core histone H2A variant that contains an absolutely conserved serine/glutamine (SQ) motif within an extended carboxy-terminal tail. H2AX phosphorylation at the SQ motif (gamma-H2AX) has been shown to increase dramatically upon exogenously introduced DNA double-strand breaks (DSBs). In this study, we use quantitative in situ approaches to investigate the spatial patterning and cell cycle dynamics of gamma-H2AX in a panel of normally growing (unirradiated) mammalian cell lines and cultures. We provide the first evidence for the existence of two distinct yet highly discernible gamma-H2AX focal populations: a small population of large amorphous foci that colocalize with numerous DNA DSB repair proteins and previously undescribed but much more abundant small foci. These small foci do not recruit proteins involved in DNA DSB repair. Cell cycle analyses reveal unexpected dynamics for gamma-H2AX in unirradiated mammalian cells that include an ATM-dependent phosphorylation that is maximal during M phase. Based upon similarities drawn from other histone posttranslational modifications and previous observations in haplo-insufficient (H2AX-/+) and null mice (H2AX-/-), gamma-H2AX may contribute to the fidelity of the mitotic process, even in the absence of DNA damage, thereby ensuring the faithful transmission of genetic information from one generation to the next. (+info)Dynamic changes in histone H3 lysine 9 methylations: identification of a mitosis-specific function for dynamic methylation in chromosome congression and segregation. (8/24)
Histone methylation is unique among post-translational histone modifications by virtue of its stability. It is thought to be a relatively stable and heritable epigenetic mark for gene-specific regulation. In this study, we use quantitative in situ approaches to investigate the cell cycle dynamics of methylated isoforms of histone H3 lysine 9. Contrary to the expected stability of trimethylated lysines, our results for trimethylated lysine 9 (tMeK9) of H3 demonstrate that the genomic content of this methylation undergoes significant changes as cells progress through mitosis. Unexpectedly, there is a loss of tMeK9 that appears to reflect a robust demethylase activity that is active during the period between anaphase and cytokinesis. Subsequent investigations of mitoses in tMeK9-deficient cells revealed defects in chromosome congression and segregation that are distinct from the increased cohesion at centromeres previously reported in association with the loss of tMeK9. Collectively, these results identify a mitosis-specific trimethylation of Lys9 in pericentromeric heterochromatin that functions in the faithful segregation of chromosomes. (+info)I apologize for any confusion, but "Muntjacs" is not a medical term. It refers to a group of small deer species native to southern and southeastern Asia. The term "Muntjac" is a common name used in zoology, not medicine. If you have any questions related to medical terminology or concepts, I would be happy to help with those instead.
I apologize for any confusion, but "deer" is not a medical term. It is a common name used to refer to various species of hooved mammals belonging to the family Cervidae. If you have any questions about medical terminology or health-related topics, I would be happy to help answer them.
Transfer RNA (tRNA) is a type of RNA molecule that plays a crucial role in protein synthesis. It carries amino acids to the ribosome, where they are incorporated into growing polypeptide chains during translation, the process by which the genetic code in mRNA is translated into a protein sequence.
tRNAs have a characteristic cloverleaf-like secondary structure and a stem-loop tertiary structure, which allows them to recognize specific codons on the mRNA through base-pairing between their anticodon loops and the complementary codons. Each tRNA is specific for one amino acid, and there are multiple tRNAs for each amino acid that differ in their anticodon sequences, allowing them to recognize different codons that specify the same amino acid.
"His" refers to the amino acid Histidine, which is encoded by the codons CAU and CAC on mRNA. Therefore, tRNA-His is a type of tRNA molecule that carries the amino acid Histidine to the ribosome during protein synthesis.
Scent glands are specialized sebaceous (oil) or sudoriferous (sweat) glands in various animals that produce and release scents for different purposes, such as marking territory, attracting mates, or providing warning signals. These scents can be released through various methods, including rubbing, spraying, or secreting onto fur or skin. Examples of scent glands include the anal glands in dogs and cats, the musk glands in deer, and the civet gland in civets. In humans, scent glands are not as developed or specialized, but some sebaceous glands can produce scents associated with personal body odor.
Transfer RNA (tRNA) is a type of RNA molecule that plays a crucial role in protein synthesis in the cell. It carries and transfers specific amino acids to the growing polypeptide chain during translation, the process by which the genetic code in mRNA is translated into a protein sequence.
tRNAs have a characteristic cloverleaf-like secondary structure and a stem-loop tertiary structure, which allows them to bind both to specific amino acids and to complementary codon sequences on the messenger RNA (mRNA) through anticodons. This enables the precise matching of the correct amino acid to its corresponding codon in the mRNA during protein synthesis.
Ser, or serine, is one of the 20 standard amino acids that make up proteins. It is encoded by six different codons (UCU, UCC, UCA, UCG, AGU, and AGC) in the genetic code. The corresponding tRNA molecule that carries serine during protein synthesis is called tRNASer. There are multiple tRNASer isoacceptors, each with a different anticodon sequence but all carrying the same amino acid, serine.
Artificial bacterial chromosomes (ABCs) are synthetic replicons that are designed to function like natural bacterial chromosomes. They are created through the use of molecular biology techniques, such as recombination and cloning, to construct large DNA molecules that can stably replicate and segregate within a host bacterium.
ABCs are typically much larger than traditional plasmids, which are smaller circular DNA molecules that can also replicate in bacteria but have a limited capacity for carrying genetic information. ABCs can accommodate large DNA inserts, making them useful tools for cloning and studying large genes, gene clusters, or even entire genomes of other organisms.
There are several types of ABCs, including bacterial artificial chromosomes (BACs), P1-derived artificial chromosomes (PACs), and yeast artificial chromosomes (YACs). BACs are the most commonly used type of ABC and can accommodate inserts up to 300 kilobases (kb) in size. They have been widely used in genome sequencing projects, functional genomics studies, and protein production.
Overall, artificial bacterial chromosomes provide a powerful tool for manipulating and studying large DNA molecules in a controlled and stable manner within bacterial hosts.