Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Within- and between-species variation in restriction endonuclease recognition sites was examined at the Y-linked RPS4Y locus of six hominoid species: human (Homo sapiens), gorilla (Gorilla gorilla), chimpanzee (Pan troglodytes), bonobo (Pan paniscus), orangutan (Pongo pygmaeus), and gibbon (Hylobates lar). RPS4Y is an expressed gene that maps to the non-recombining region of the Y chromosome. An approximately 1,490 base pair fragment of the RPS4Y gene, including all of intron 3, was amplified by PCR from DNA extracted from each of the six species. Forty-seven restriction sites were identified on the six-species composite map derived from double-digest restriction analyses of the amplified fragment. As expected, maximum parsimony analysis indicated that chimpanzee and bonobo are the two most closely related living hominoids. The same analysis suggested that the closest living relative of Homo is Gorilla, not Pan, although support for this relationship was relatively weak. These results disagree with recently published phylogenies based on analyses of mtDNA sequences (Horai et al. [1995] Proc. Natl. Acad. Sci. U.S.A. 88:7401-7404) and the Y-linked ZFY locus (Dorit et al. [1995] Science 268:1183-1185). A combined data set derived from three distinct Y-linked loci-RPS4Y, SRY, and ZFY-was also analyzed. The maximum parsimony topology for the combined data provided only weak support for a shared common ancestor for Homo and Pan subsequent to divergence from the Gorilla lineage. Taken together, the data from the Y chromosome do not provide unequivocal support for any single, dichotomously branching species tree linking Homo, Pan, and Gorilla.
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PMID:Interspecific variation at the Y-linked RPS4Y locus in hominoids: implications for phylogeny. 892 80

Mitochondrial DNA (mtDNA) sequence variation was examined in 37 Seminoles from Florida by polymerase chain reaction amplification and high resolution restriction endonuclease analysis. The Y chromosome TaqI restriction fragment length polymorphisms detected by the probes 49a, 49f, and 12f2 were examined in the 26 males of this group. Analysis of the mtDNA revealed that all four Native American haplogroups (A, B, C and D) were present in the Seminoles encompassing about 95% of the Seminole mtDNAs. No European mtDNAs were found among the Seminoles, but two mtDNAs (about 5%) were members of the African-specific haplogroup L1, thus indicating that a limited number of African women were incorporated in the Seminole tribe. Analysis of Y chromosome haplotypes supports the hypothesis that haplotypes 18 and 63 are the most likely founding Native American Y chromosome haplotypes from Asia. However, 11% of the Seminole Y chromosomes represented haplotypes generally attributed to Europeans, though none harbored standard African haplotypes. These findings support historical evidence that the Seminole tribe has integrated individuals of European and African ancestry, but suggests that the sex ratio of nonnatives from different continents may have varied.
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PMID:Mitochondrial DNA and Y chromosome-specific polymorphisms in the Seminole Tribe of Florida. 915 18

In order to elucidate the structural chromosome organization of the heterochromatic regions in sheep, we have used C-banding, silver-staining, sequential CDD technique and restriction endonuclease banding. By these banding techniques we obtained four fractions of repetitive DNA, the autosomal fractions A and B, the C fraction in the X chromosome, and the D fraction in the Y chromosome. Silver staining revealed active nucleolus organizer regions (NOR's) on the telomeric GC-rich areas of chromosomes 1, 2, 3, 4, and 25 which were digested with HaeIII restriction endonuclease.
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PMID:Characterization of the heterochromatic chromosome regions in sheep. 954 6

The analysis of patterns of X-chromosome inactivation is becoming increasingly utilized as a marker of clonal composition of tissues from women. To date, however, no analogous system has been found for the study of clonality in tissue from men. In the current study, the methylation patterns for portions of the amelogenin genes are tested, which are encoded on both the X- and Y-chromosome (AMGX and AMGY). The polymerase chain reaction (PCR) was used to amplify portions of AMGX and AMGY from genomic DNA of carcinomas of the colon, lung, liver and kidney, as well as from matched normal somatic tissues. The amplification target included Alu I methylation sensitive restriction endonuclease sites as well as a 189 bp sequence which is present in AMGX but is absent in AMGY. Polymerase chain reaction amplification of AMGX and AMGY was successful using genomic DNA from both tumour and normal control tissue in 24 of the 26 cases. Pretreatment of genomic DNA with Alu I blocked amplification of AMGX in all cases from both normal tissue and tumour. This indicates that AMGX and AMGY undergo a non-random pattern of methylation in both normal tissues and in tumours, precluding their use as a marker of clonality. Methylation of Alu I sites in AMGY suggests that the amelogenin genes undergo dosage compensation, which raises the possibility that the expression of amelogenin is not restricted to the development of the tooth bud but may also play some other role in various tissues of the body.
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PMID:Amelogenin dosage compensation in carcinoma of colon, lung, liver and kidney, is not a marker of clonality in males. 972 93

We report a case of mos 45,X/46,X,+mar, diagnosed prenatally by amniocentesis, whose physical examination, including external and internal organs, along with serum testosterone values were normal five years after delivery. The mosaic karyotype was seen in 146 of 240 cells examined (amniotic fluid cells, 110/65; placental chorionic villi: 5/4; cord blood, 21/81; cultured skin fibroblasts, 10/90) from 386 metaphases, and the marker chromosome appeared as a small non-fluorescent acrocentric chromosome. All autosomes appeared normal, and no normal Y chromosome could be demonstrated. Analysis of 26 Y-chromosome loci by molecular techniques such as PCR, Southern analysis using multiple Y-specific DNA probes, and Hae III restriction endonuclease assessment of male-specific repeated DNA in the heterochromatic region of the Y chromosome, and fluorescence in situ hybridization (FISH), revealed the marker was derived from a Y chromosome including p terminal to q11.23, and paracentric inversion in the remaining Y long arm. The formation of testes can be considered as existence of SRY (sex-determining region of Y) as a testis-determining factor. The present report illustrates the importance of FISH and molecular techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.
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PMID:Prenatal identification of mos 45,X/46,X,+mar in a normal male baby by cytogenetic and molecular analysis. 988 26

In many cells, the process of apoptosis is accompanied by endonuclease-mediated double-strand cleavage of DNA between nucleosomes, resulting in the production of discrete fragments of 200 bp or multiples thereof. To address the question of whether this endonuclease attack occurs randomly or nonrandomly along chromosomes, we first constructed chromosome fluorescence in situ hybridization probes from the 200- and 400-bp fragments from gamma-irradiated apoptotic human T cells along with similar-sized probes from randomly sheared DNA of nonirradiated cells. These probes were compared for their binding along normal human metaphase chromosomes after fluorescence in situ hybridization with and without the presence of unlabeled total human blocking DNA. The addition of blocking DNA to the apoptotic probes revealed a nonrandom pattern of hybridization that was not observed for the nonirradiated control probes. The most obvious areas of selective binding occurred around the centromeric and other heterochromatic regions along the chromosome arms, such as the long (q arm) of the Y chromosome. The converse of this experiment was also carried out. DNA probes from heterochromatic and euchromatic regions of the human Y chromosome were hybridized onto slot blots of apoptotic ladder-sized and randomly sheared nonirradiated human T-lymphocyte DNA. The slot blot results showed that for an equal mass of ladder-sized apoptotic DNA and randomly sheared nonirradiated control DNA, the apoptotic DNA sample contains a relatively larger proportion of Y heterochromatin DNA sequences (approximately 2.5-fold). Together, these results indicate that apoptosis-mediated endonuclease attack does not occur randomly in the genome but occurs preferentially in heterochromatin.
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PMID:Nonrandom degradation of DNA in human leukemic cells during radiation-induced apoptosis. 1044 86

Comparative cytogenetic analyses were performed with ten different banding methods on a previously undescribed, inherited structural aberration of a Y chromosome, and the results compared with those of normal Y chromosomes occurring in the same family. The value of the individual staining techniques in investigations of Y chromosomal aberrations is emphasized. The aberrant Y chromosome analyzed can be formally derived from an isodicentric Y chromosome for the short arm with a very terminal long-arm breakpoint, in which the centromere, an entire short arm, and the proximal region on one long arm was lost. This interpretation was confirmed by determining the amount of the two Y-specific DNA sequences (2.1 and 3.4 kb in length) by means of Hae III restriction endonuclease analysis. The karyotype-phenotype correlations in the men with this aberrant Y chromosome, especially the fertility dysfunctions (oligoasthenoteratozoospermia, cryptozoospermia), are discussed. The possibility of the existence of fertility factors involved in the control of spermatogenesis within the quinacrine-bright heterochromatic region of the Y long arm is presented.
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PMID:Characterization of a new aberration of the human Y chromosome by banding methods and DNA restriction endonuclease analysis. 1081 18

Chromosomes of a species of Eigenmannia presenting a X1X1X2X2:X1X2Y sex chromosome system, resulting from a Y-autosome Robertsonian translocation, were analyzed using the C-banding technique, chromomycin A3 (CMA3) and mithramycin (MM) staining and in situ digestion by the restriction endonuclease AluI. A comparison of the metacentric Y chromosome of males with the corresponding acrocentrics in females indicated that a C-band-positive, CMA3/MM-fluorescent and AluI digestion-resistant region had been lost during the process of translocation, resulting in a diminution of heterochromatin in the males. It is hypothesized that the presence of a smaller amount of G + C-rich heterochromatin in the sex chromosomes of the heteromorphic sex when compared with the homomorphic sex may be associated with the sex determination mechanism in this species and may be a more widely occurring phenomenon in fish with differentiated sex chromosomes than was initially thought.
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PMID:Sex chromosome evolution in fish: the formation of the neo-Y chromosome in Eigenmannia (Gymnotiformes). 1092 98

Homing endonuclease genes (HEGs) encode proteins that in the heterozygous state cause double-strand breaks in the homologous chromosome at the precise position opposite the HEG. If the double-strand break is repaired using the homologous chromosome, the HEG becomes homozygous, and this represents a powerful genetic drive mechanism that might be used as a tool in managing vector or pest populations. HEGs may be used to decrease population fitness to drive down population densities (possibly causing local extinction) or, in disease vectors, to knock out a gene required for pathogen transmission. The relative advantages of HEGs that target viability or fecundity, that are active in one sex or both, and whose target is expressed before or after homing are explored. The conditions under which escape mutants arise are also analyzed. A different strategy is to place HEGs on the Y chromosome that cause one or more breaks on the X chromosome and so disrupt sex ratio. This strategy can cause severe sex-ratio biases with efficiencies that depend on the details of sperm competition and zygote mortality. This strategy is probably less susceptible to escape mutants, especially when multiple X shredders are used.
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PMID:The population genetics of using homing endonuclease genes in vector and pest management. 1866 May 32

We have exploited the high selectivity of the homing endonuclease I-PpoI for the X-linked Anopheles gambiae 28S ribosomal genes to selectively target X chromosome carrying spermatozoa. Our data demonstrated that in heterozygous males, the expression of I-PpoI in the testes induced a strong bias toward Y chromosome-carrying spermatozoa. Notably, these male mosquitoes also induced complete early dominant embryo lethality in crosses with wild-type females. Morphological and molecular data indicated that all spermatozoa, irrespectively of the inheritance of the transgene, carried a substantial amount of I-PpoI protein that could attack the maternally inherited chromosome X of the embryo. Besides the obvious implications for implementing vector control measures, our data demonstrated the feasibility of generating synthetic sex distorters and revealed the intriguing possibility of manipulating maternally inherited genes using wild-type sperm cells carrying engineered endonucleases.
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PMID:Targeting the X chromosome during spermatogenesis induces Y chromosome transmission ratio distortion and early dominant embryo lethality in Anopheles gambiae. 1905 70


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