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At least 1,261 records · Page 70Linked to original sources
PubMed1984

Pure monosomy and trisomy 2q24.2----q3105 due to an inv ins(7;2)(q21.2;q3105q24.2) segregating in four generations.

An inv ins(7;2)(q21.2;q3105q24.2) was found to segregate through four generations of a family. Adjacent-1 segregation aneusomies were ascertained in five patients: three monosomics and two trisomics; and the corresponding syndromes were delineated. The comparative analysis between these and other previously described 2q aneusomic individuals led to the conclusion that a large cleft between first and second toes is a constant feature in monosomy 2q24----q31. No other trait could plausibly be mapped. Risks of 7.9 to 31.6% for aneusomic children and of 26.3% for abortion were estimated in the present family.

Bone and Bones↗
PubMed1995

Segregational stability and copy number of the theta-type lactococcal replicon Rep22 in Lactococcus.

Rep22 is the replication region of the lactococcal theta replicating pUCL22 plasmid. The copy number of Rep22-based plasmids in Lactococcus was determined by using a chromosomal DNA fragment from Lactococcus lactis subsp. lactis MMS368 as reference. Segregational behavior appeared to be linked to copy number and therefore indicated random distribution of copies to daughter cells. Nevertheless, an active partitioning system was detected in the parental plasmid pUCL22. A pUCL22 138-bp DNA restriction fragment bearing a perfect 18-bp inverted repeat was involved in the improvement of Rep22-based plasmid segregational stability during discontinuous exponential growth.

Base Sequence↗
PubMed1976

G6PD Lozere and Trinacria-like. Segregation of two non hemolytic variants in a French family.

Two new G6PD variants have been found in red blood cells of the members of a French family originating from Lozere. The father is hemizygous for an electrophoretically fast variant with mild enzyme deficiency (50--60% of normal). The abnormal paternal G6PD gene is segregating in his daughter who is double heterozygous for maternal and paternal variants. This mutant enzyme, different from previously described variants is designated as Gd Lozere. The mother is heterozygous for another G6PD variant. Two sons are hemizygous for this latter mutant enzyme characterized by a moderate deficiency (25--30% of normal) and slower electrophoretic mobility with some slightly altered kinetic properties. This G6PD had been identified as Gd Trinacria like. These two abnormal enzymes are not associated with any hemolytic problem. Case reported is the first showing the segregation of two new mutant enzymes, distinct from common G6PD variants, among the members of the same family.

Electrophoresis, Starch Gel↗
PubMed1988

Familial Alzheimer's disease (FAD): co-segregation between alleles at the D21S11 DNA marker and the FAD gene in a particular pedigree.

Segregation studies of Alzheimer's disease (AD) gene and a cloned DNA probe (D21S11), which detects an EcoRI restriction fragment length polymorphism for a sequence located in the medial part of the long arm of chromosome 21, are reported in a large pedigree, in which AD is transmitted as an autosomal dominant mendelian trait. In this pedigree, the AD gene co-segregation with one of the alternative alleles at the probe raises the possibility of using such a marker for presymptomatic diagnosis of individuals at risk for the disease.

Alzheimer Disease↗
PubMed1994

Assignment of RFLP, RAPD and isoenzyme markers to Aspergillus nidulans chromosomes, using chromosome-substituted segregants of a hybrid of A. nidulans and A. quadrilineatus.

Chromosome-substituted haploid segregants were selected from among the benomyl-induced progeny of an interspecific hybrid produced by polyethylene-glycol-induced fusion of protoplasts of an Aspergillus nidulans 'master strain' and an A. quadrilineatus auxotrophic mutant. These segregants were examined by RFLP, RAPD, and isoenzyme analysis. The A. nidulans ribosomal repeat unit was assigned to chromosome V, while the benA and the pyrG genes were assigned to linkage groups VIII and I, respectively, of A. nidulans. None of the other cloned genes tested (gdhA, amdS and 25s rRNA) showed polymorphism between the two parents. The method was also used to assign RAPD markers and isoenzyme bands of beta-arylesterase, phosphatases, NAD-dependent malate dehydrogenase, and cellulase, to A. nidulans chromosomes and/or to their A. quadrilineatus equivalents. The isoenzyme and DNA sequences assigned to chromosomes could be used to saturate the genetic map of A. nidulans, or could serve as starting points for the construction of a genetic map of A. quadrilineatus. No method affording the same possibilities has been described so far in Aspergilli. This chromosome-assay method may be a useful alternative to pulsed-field-gel electrophoretic procedures for the assignment of molecular markers to chromosomes.

Aspergillus↗
PubMed1993

In situ analysis of centromere segregation in C57BL/6 x Mus spretus interspecific backcrosses.

The analysis of major satellite sequence differences between Mus spretus and laboratory mice provides a robust method for analyzing the centromere location for the genetic maps of each mouse chromosome. Fluorescence in situ hybridization (FISH) of a genomic probe, pMR196, for the laboratory mouse major satellite sequences was used to identify C57BL/6Ros (B6) pericentromeric heterochromatin in progeny of reciprocal backcross matings. These included 80 (B6 x M. spretus)F1 x M. spretus progeny (BSS) and 70 (B6 x M. spretus)F1 x B6 (BSB) progeny. FISH analysis of pericentromeric heterochromatin was conducted on the same metaphase spreads that were karyotypically analyzed for chromosome-specific banding patterns. Analysis of chromosomal segregation suggested that there was not primary deviation from random assortment during meiosis in the interspecific hybrid female, because nearly all of the 190 pair-wise comparisons did not deviate from expected and because there was no consistent pattern of deviation of the same chromosomes in the reciprocal backcross progeny from similar (C57BL/6 x M. spretus)F1 hybrid females. These results affirm the value of using the major satellite to genetically mark pericentromeric heterochromatin in the analysis of the segregation and assortment of centromeres in Mus interspecific crosses.

Animals↗
PubMed1983

Specific immune responses after booster immunization with tetanus toxoid in man: study of kinetics, family segregation, and linkage to HLA of in vitro lymphocyte proliferative responses and serum-antibody responses.

Kinetics and family transmission of antigen-specific in vitro cell-mediated responses were investigated in 68, and serum-antibody responses to tetanus toxoid (TT) in 73 individuals from a total of 12 families. Proliferative responses to highly purified TT monomer were studied in 6- to 7-day lymphocyte cultures. The effect of booster immunization was detectable 7 (D7) and 30 (D30), but not 120 days (D120) later. The sex of donors was not found to have any influence. A significant influence of the time interval since the last immunization was found for the responses at D7 and D30. Data were correspondingly adjusted for segregation and linkage analyses. Several transmission hypotheses for the data obtained at D7 and D30 were evaluated by likelihood ratio tests. Observations at D30 were compatible with the hypothesis of a control by a dominant genetic determinant for high responses closely linked to the major histocompatibility complex region. No such evidence could be found for D7. After booster immunization, mean antibody levels determined on D7, D30 (peak of response), and D120 were found to be higher than those prior to immunization (D0). The sex of the donors was found to have no influence on antibody responses. The time interval since the last immunization and the age of donors both had a slight influence, and data were correspondingly adjusted for segregation and linkage analyses, which showed no evidence of genetic control of the antibody responses or of linkage to HLA.

Adolescent↗
PubMed1994

Segregation analysis of NIDDM in Caucasian families.

Non-insulin-dependent diabetes mellitus (NIDDM) has a substantial genetic component, but the mode of inheritance and the molecular basis are unknown. We have undertaken segregation analysis of NIDDM after studying 247 subjects in 59 Caucasian nuclear pedigrees ascertained without regard to family history of the disorder. The analyses were performed using POINTER and COMDS, which are computer programs which apply statistical models to the data. POINTER analysis was performed defining the phenotype as a presence or absence of hyperglycaemia. Among single locus hypothesis, the analyses rejected a recessive model and favoured a dominant model, but could not statistically show that this fitted better than a mixed model (a single locus against a polygenic background) or a polygenic model. COMDS analysis assumed a continuum of hyperglycaemia from normality to NIDDM, classified family members into a series of diathesis classes with increasing plasma glucose levels and compared the distribution with that found by screening the normal population. This analysis improved the likelihood of a dominant single locus model and suggested a gene frequency of 7.4%. It raised the possibility of a second locus, but cannot identify or exclude a polygenic model. In conclusion, two types of segregation analyses rejected a recessive model and favoured a dominant model of inheritance, although they could not statistically show that this fitted better than the polygenic model. The results raised the possibility of a common dominant gene with incomplete penetrance, but genetic analysis of NIDDM needs to take into account the likelihood of polygenic inheritance with genetic heterogeneity.

Adult↗
PubMed1991

Chromosome recombination and defective genome segregation induced in Chinese hamster cells by the topoisomerase II inhibitor VM-26.

We found that 4'-demethylepipodophyllotoxinthenylidene-beta-D-glucoside (VM-26; Teniposide), which specifically inhibits the enzyme DNA topoisomerase II, induces the formation of quadriradial chromosomes in Chinese hamster ovary cells. VM-26 traps topoisomerase II molecules when they are covalently integrated into DNA during their reaction. Quadriradial chromosomes are formed by reciprocal exchange of double-stranded DNA between single chromatids of two different chromosomes. Using synchronised cells, we found that they were formed after a single replication cycle in the presence of VM-26 at a low concentration (0.008 micro M), which does not affect DNA replication, and occurred in 50% of the mitotic cells at a concentration of 0.16 micro M. They were also formed when VM-26 was present for only 1.5 h before mitosis, after the completion of S-phase DNA replication. Chromatids bearing a translocated segment of another chromatid, which were derived from recombined chromosomes, were observed in late metaphase cells. Segregation of the daughter genomes was defective in many mitotic cells, probably because chromatids with two or no centromeres and kinetochores, formed from chromosomes recombined between their centromeres, could not be segregated. In the light of evidence that topoisomerase II molecules covalently integrated in DNA are trapped and therefore more abundant in the presence of VM-26, and that this enzyme can effect recombination of double-stranded DNA in vitro, we interpret these observations as evidence that topoisomerase II can mediate chromosome recombination in vivo.

Animals↗
PubMed1978

Segregation of genetic determinants for murine glucuronidase synthesis and loss in CXB recombinant-inbred strains.

A set of recombinant-inbred strains developed from mouse strains BALB/c and C57BL/6 includes two beta-glucuronidase phenotypes that are not seen in either of the progenitor strains. These new recombinant phenotypes indicate that glucuronidase levels are regulated by genes additional to the Gur locus, which is closely linked to the glucuronidase structural gene (Gus) and is known to regulate the rate of glucuronidase synthesis. In this study, induced rates of glucuronidase synthesis were determined for these recombinant-inbred strains, and rate constants for enzyme loss were calculated. The rate of synthesis was found to segregate with the Gus gene in all of the strains, and only the determinants for rate of enzyme loss recombined to give new phenotypes. It was concluded that at least two genes affect the rate of enzyme loss, that these genes are not closely linked to each other or to the Gur-Gus region on chromosome 5, and that no major determinants of glucuronidase synthesis segregate independently of Gur.

Animals↗
PubMed1984

Distorted segregation and linkage of alcohol dehydrogenase genes in Camellia japonica L. (Theaceae).

Alcohol dehydrogenase isozymes in Camellia japonica are encoded by two genes, Adh-1 and Adh-2. Both loci are expressed in seeds, and their products randomly associate into intragenic and intergenic dimers. Electrophoresis of leaf extracts reveals only the products of Adh-2. Formal genetic analysis indicated that the two Adh loci are tightly linked (combined estimate of r = 0.004). Most segregations fit expected Mendelian ratios, but in some families distorted segregation was observed at Adh-1, Adh-2, or both loci. The deficient progeny class varied across families, and in two apparent back-crosses three rather than two phenotypic classes were recovered. The mechanism underlying these distortions is not known, but evidence is presented that suggests that the phenomenon is genic or segmental in nature. Plausible hypotheses include linkage of the Adh structural genes with a gametophytic self-incompatibility locus, translocation heterozygosity involving the segment bearing Adh-1 and Adh-2, or a combination of these two mechanisms.

Alcohol Dehydrogenase↗
PubMed1982

Genetic variation and joint segregation of biochemical loci in the common meadow mushroom, Agaricus campestris.

In this paper we report the results of an electrophoretic examination of genetic variation in the common meadow mushroom, Agaricus campestris. An examination of variability at 10 biochemical loci in a single natural population revealed an average heterozygosity of 0.281. Mendelian segregation was verified for 13 loci in single-spore-derived lines from individual sporophores. One linkage was found (Gpt-2 with Pep-GL-1, r = 0.065) among 47 pairwise examinations for joint segregation.

Basidiomycota↗
PubMed1981

Cytochemical evidence for the segregation of adenylate cyclase, Ca2+-, Mg2+-ATPase, K+-dependent p-nitrophenyl phosphatase in separate membrane compartments in human platelets.

The blood platelet has three morphologically distinct membrane systems. In addition to the plasma membrane the platelet has an 'open canalicular system' (surface-connected intracytoplasmic membrane system) and a microsome-like 'dense tubular system'. The open canalicular and dense tubular systems have been implicated in Ca2+ transport, cyclic nucleotide (cAMP) synthesis and prostaglandin and thromboxane synthesis. Precise definition of the function of the different membrane systems requires analysis of their unique chemical activities. Broken cell preparations are used to advantage for such studies. However, clean separation and definition of the origin and composition of the membrane fractions has been difficult because well-defined marker enzymes for the various membrane systems have not been conclusively established. Platelets were fixed for 5 min in 1% paraformaldehyde-0.2% glutaraldehyde and assayed for K+-dependent p-nitrophenyl phosphatase, Ca2+-, Mg2+-ATPase and adenylate cyclase K+-dependent p-nitrophenyl phosphatase was localized only at the plasma membrane while Ca2+-, Mg2+-ATPase and adenylate cyclase were found relatively segregated to the open canalicular and dense tubular systems. The segregation of these enzymes to separate membrane compartments may have significant implications with regard to understanding platelet function.

4-Nitrophenylphosphatase↗
PubMed1993

Segregation analysis of speech and language disorders.

Complex segregation analysis was performed on pedigrees ascertained through 45 probands (26 males, 19 females) with a history of preschool speech and language disorders. Hypotheses concerning mode of inheritance were tested using the POINTER segregation analysis program. Although there is strong evidence for familial transmission of this trait, we were unable to distinguish between a major gene and multifactorial transmission model using likelihood-ratio chi-square tests. Future studies with quantitative measures of speech and language disorders are needed to resolve the issue of mode of inheritance for this trait.

Adolescent↗
PubMed1975

Chinese hamster X mouse hybrid cells segregating mouse chromosomes and isozymes.

Hybrid cells are readily formed by fusing clonal Chinese hamster cells to fresh, noncultured, adult mouse spleen cells followed by isolation in selective medium. The vast majority of such hybrids retain Chinese hamster chromosomes and isozymes while segregating mouse chromosomes and isozymes. The growth, plating efficiency, ease of karyology, and rapid segregation of mouse markers allows linkage tests in primary clones. Analysis of 13 isozymes showed 12 to be asyntenic and on epair (PGD-PGM2) to be syntenic This system will allow extensive somatic cell hybrid gene mapping in the mouse and permit a comparison of human and mouse linkage relationships.

Animals↗
PubMed1978

Induced segregation of human syntenic genes by 5-bromodeozyuridine + near-visible light.

Chromosome-breaking agents have been used in two different procedures for promoting segregation of syntenic genes on human chromosome 12. In method A, a human-Chinese hamster cell hybrid containing the single human chromosome 12 was treated either with 5-bromodeoxyuridine BrdU + near-visible light or with X-rays. In method B, normal human fibroblasts were treated with BrdU + near-visible light followed by their fusion with a Chinese hamster glycine-requiring cell mutant CHO-K1/gly-A. Since the human complementing gene for serine hydroxymethyltransferase, an enzyme deficient in gly-A, lies on human chromosome 12, only those hybrids retaining that chromosome can survive the glycine-free medium. Clones isolated from both procedures were analyzed for the loss or retention of four other syntenic genes on chromosome 12, TPI, GAPD, LDH B, and PepB. The results demonstrate that method B is much more effective in generating clones with extensive marker losses. In addition, the segregation pattern and frequency obtained in this study provided information on the linear order of TPI and GAPD on chromosome 12.

Bromodeoxyuridine↗
PubMed1986

Mitotic segregation of mitochondrial DNAs in human cell hybrids and expression of chloramphenicol resistance.

The relationship between the chloramphenicol (CAP)-resistant phenotype and the mtDNA genotype was investigated in segregating human, HeLa X HT1080, somatic cell hybrids. The parental mtDNAs were quantitated in heteroplasmic cells by using restriction fragment length polymorphisms (RFLPs) detected in Southern blots. CAP-resistant (R) X CAP-sensitive (S) hybrids selected and grown in CAP for brief periods had as little as 25% CAP-R mtDNA. With prolonged selection, the CAP-R mtDNA increased to 90-95%. Hybrids selected and passaged without CAP either retained both mtDNAs or progressively lost one mtDNA (mitotic segregation). The CAP-resistance phenotype of these hybrids changed abruptly when the proportion of CAP-R mtDNAs fluctuated around approximately 10% (threshold effect). Hybrids with greater than 25% HT1080 mtDNA had an additional characteristic. They cloned better with CAP than without. The cloning efficiency in CAP of hybrids having 90% HT1080 mtDNA was more than fivefold greater than the control.

Cell Fusion↗