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In contrast to most other vertebrates,teleost fish exhibit an unparalleled capacity to generate stem cells in both the intact and the injured adult brain.My research is focused on the occurrence, the extent and the fate of aneuploid cells (genome-modified individual cells characterized by the loss or gain of whole chromosomes) generated in the teleostean brain. Aneuploidy arises through various chromosome segregation defects during the mitotic divisions of newly-generated cells in the adult brain. Aneuploidy is observed in ~80% of the newly-generated stem cells of the adult brain,but occurs at a very low rate in liver tissue, as shown by metaphase chromosome spreads and flow-cytometric DNA content analysis. The mitotic machinery of adult brain cells was examined for chromosome segregation defects which showed lagging chromosomes at metaphase and anaphase, as well as micronuclei and anaphase bridges,in the intact adult brain. In conclusion,my research demonstrates the evidence of the generation and maintenance of aneuploid cells in the adult fish brain that arise through chromosome missegregation which is a widespread phenomenon in the teleostean central nervous system.
Chromosomes in humans occasionally break and an exchange, inversion or other more complex rearrangement of the broken pieces can occur. If the breakage causes no damage to essential gene function, and if no overall loss of chromosome material takes place, these rearrangements can remain undetected in healthy carriers. Problems occur when cell division, involving rearranged chromosomes in the germ line, leads to an unbalanced distribution of chromosomal material in the resulting gametes. Depending on how much chromosomal material is involved, the imbalance can cause fertility problems to severe birth defects in the offspring. This book describes a study attempting to identify hot spots for breakage on human chromosomes, in a search for clues to the origin of constitutional chromosome rearrangements. Identifying true hot spots is complicated by ascertainment bias which comes about frequently due to the often severe phenotypic manifestations of chromosome rearrangements. Through accounting for the various sources of bias, a number of candidates for constitutional chromosome rearrangement hot spots are identified.
Male infertility is a multifactorial syndrome encompassing a wide variety of ?disorders. In more than half of infertile men, the cause of their infertility is ?mysterious (idiopathic) and could be congenital or acquired.? The causes are known in less than half of these cases, out of which genetic or ?inherited disease and specific abnormalities in the Y chromosome are major ?factors. About 10–20 percent of males presenting without sperm in the ?ejaculate carry a deletion of the Y chromosome Male genetic factor of infertility accounts for about half the cases of couple ?infertility and in around 50% of cases its etiology remains unknown. Molecular ?genetic techniques have unveiled a number of etiopathogenetic factors, ?including microdeletions of the Yq. Y chromosome microdeletions removing ?the AZoospermia Factor (AZF) regions are the most frequent molecular genetic ?causes of oligo/azoospermia).?
Acetylation of explicit residues of histones is associated with gene activity and may play elementary role in transcriptional regulation. Bromodomains, motifs found in several eukaryotic transcription factors, exclusively interact with acetyl-lysines in histones. p300 is functionally conserved transcriptional coactivators for various transcription factors and have intrinsic acetyltransferase activity. The covalent alteration of histone tails has regulatory roles in various nuclear processes, such as organization of transcription and mitotic chromosome condensation. Among the different groups of enzymes identified to catalyze the covalent modification, the most topical additions are the histone methyltransferases (HMTases), whose functions are now being characterized. G9A is a novel mammalian HMTase that prefer lysine. Specific chromosome translocations commonly found in human leukemia engross rearrangements of genes which are implicated in the regulation of hematopoiesis. Further, the detail shows that the chromosome translocations often results in the expression of gene products.
Common (bread) wheat is an allohexaploid species (Triticum aestivum L.) with 3 compensating genomes AABBDD (2n=6x=42 chromosomes). Traditionally genetic and physical mapping in this most important cereal crop has been based on molecular markers (RFLPs, PCR, Insitu hubridisation etc). The recent development in producing deletion lines of common wheat (using Aegilops cylindricum genome) has revolutionized the physical mapping of wheat chromosomes. During present study, deletion lines of chromosomes 2A of common wheat were used to identify RAPD (Randomly Amplified Polymorphic DNA) based molecular markers specific for short and/or long arm of chromosome 2A. Out of the 7 RAPD primers used, OPA-07 showed useful polymorphism. By comparing the C-banding karyotype of the deletion lines, it is inferred that the primer (OPA-07) anneals to the distal half of the long arm of chromosome 2A.
Interspecific crosses provide a bridge by which the gene pool of rice can be increased. Attempts have been made to visualize the genomic constitution of wide-cross derivatives. Genomic in situ hybridization Oryza australiensis chromosomes and introgressed segment from O. australiensis into the Oryza sativa background have been detected. The genomic relationship between Oryza sativa (2n=24 AA) and Oryza australinesis (2n = 24 EE) these two species was assessed by using three strategies: genomic in situ hybridization (GISH), meiotic chromosome pairing, pollen and spikelet sterility. The chromosome pairing was examined in pollen mother cells of O. brachyantha, O. sativa and the hybrid between O. sativa and O. brachyantha. The hybrid was highly sterile with no pollen stain ability. Both parents showed regular meiosis with normal chromosome pairing. The F1 hybrid exhibited limited chromosome pairing. On an average, 0-2 bivalents and 20-24 univalents were recorded at metaphase-1 and 0- 1 univalent at diakinesis. The most frequent configuration was two bivalents and twenty univalent.