PubMed · 13804473
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
R A BRINK. 1960. Paramutation and chromosome organization.. https://doi.org/10.1086/403016
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Comparative analysis of the Streptomyces chromosome sequences, between Streptomyces coelicolor, Streptomyces avermitilis, and Streptomyces ambofaciens ATCC23877 (whose partial sequence is released in this study), revealed a highly compartmentalized genetic organization of their genome. Indeed, despite the presence of specific genomic islands, the central part of the chromosome appears highly syntenic. In contrast, the chromosome of each species exhibits large species-specific terminal regions (from 753 to 1,393 kb), even when considering closely related species (S. ambofaciens and S. coelicolor). Interestingly, the size of the central conserved region between species decreases as the phylogenetic distance between them increases, whereas the specific terminal fraction reciprocally increases in size. Between highly syntenic central regions and species-specific chromosomal parts, there is a notable degeneration of synteny due to frequent insertions/deletions. This reveals a massive and constant genomic flux (from lateral gene transfer and DNA rearrangements) affecting the terminal contingency regions. We speculate that a gradient of recombination rate (i.e., insertion/deletion events) toward the extremities is the force driving the exclusion of essential genes from the terminal regions (i.e., chromosome compartmentalization) and generating a fast gene turnover for strong adaptation capabilities.
Oxidative stress, deficiencies in natural processes such as chromatin packaging and abortive apoptosis are the main factors that lead to sperm DNA damage. The DNA integrity of sperm is essential for fertilization, as well as for the normal development of the blastocyst, embryo and child. There is increasing evidence that sperm DNA anomalies may lead to infertility, abortion, stillbirth, fathead and chromosomal diseases. The routine examination of semen can not identify subtle defects in sperm DNA, so several detection techniques have been developed for estimating the DNA (nuclear DNA/mitochondria DNA) integrity of sperm, which is considered to be a better marker of male fertility potential than conventional semen parameters. This review attempts at a detailed description of these detection techniques, including their principles, methods, steps and clinical application.
We applied atomic force microscopy (AFM) to investigate the surface structure of barley chromosome in combination with a chemical treatment method. As a result, we have obtained high-resolution topographic images of granular structures with a diameter of ca. 50 nm on the surface of critical-point dried metaphase chromosomes. Treatment with 2M NaCl significantly modified the chromosome surface structure: surface roughness was increased and chromosome thickness was decreased. The NaCl treatment extracted two major proteins with molecular weights of 4000 and 20,000 Da. These proteins might be belonging to non-histone protein families that do not contain any aromatic amino acid. The results demonstrate the advantage of the combined method of high-resolution AFM imaging and chemical treatments for understanding nano-scale surface structures of the chromosome.