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PubMed1997

Cytogenetic analysis of meiotic segregation in sperm from two males heterozygous for reciprocal translocations using PRINS and humster techniques.

The meiotic segregation patterns of 2 reciprocal translocations t(7;9)(q33;p21) and t(7;18)(q35;q11) were analyzed in sperm of 2 heterozygote carriers. Both sperm karyotyping and in situ PRINS labeling of sperm nuclei were performed on a sperm sample from each subject. Using the humster technique, 54 and 72 sperm chromosome complements were successfully analyzed for the t(7;9) and the t(7;18) respectively. The frequencies of alternate, adjacent 1, adjacent 2 and 3:1 segregations were 44.44%, 37.04%, 12.96% and 5.56% for the t(7;9) and 33.33%, 43.05%, 19.45% and 4.17% for the t(7;18). The PRINS procedure allowed the rapid screening of large samples of spermatozoa. However, alternate and adjacent 1 segregants were not discriminated because of the generation of centromeric signals. The segregation pattern was determined on 10,658 spermatozoa for the t(7;9) and 10,462 for the t(7;18). The distributions of segregants were similar to those obtained by sperm karyotyping. These data were pooled with results from 37 reciprocal translocations previously studied by sperm karyotyping and 6 recently investigated by FISH. The analysis of these compiled data demonstrates the particularity of the production of imbalances in male gametes; independent of the predisposition for a type of imbalance at term, there is a preferential production of adjacent 1 imbalance in sperm.

Adult↗
PubMed1990

Segregation and sporadic cases of Duchenne muscular dystrophy in the Henan Province, China.

In the Henan province, China, the segregation ratio of Duchenne muscular dystrophy, estimated through classical segregation analysis on 103 sibships, is p = 0.462, and the maximum likelihood proportion of sporadic cases is x = 0.264. These figures are in agreement with the results of segregation analysis on 1,800 families from different countries; also, the Henan population shows a slight segregation distortion and lacks a fraction of the sporadic cases predicted under mutation-selection equilibrium. Although not statistically significant, the downward departure of the estimated parameters from their expectations under the mendelian equilibrium hypothesis (p = 0.5; x = 0.333) confirms an anomalous segregation pattern for Duchenne muscular dystrophy. A possible role of germinal mosaicism in concealing a fraction of sporadic cases is discussed.

China↗
PubMed1989

Line segregation.

Six experiments investigated the preattentive segregation of line-like patterns composed of discrete elements in a background of distractors. The results indicate that other factors in addition to spatial density influence line segregation. Edge alignment, edge length and principal axis orientation also affect line segregation. Differences in the outputs of Gabor filters fail to account for the perceived segregation of the lines. Possible models of line segregation based on element grouping, feature density and search are briefly discussed.

Contrast Sensitivity↗
PubMed1997

Transcriptional regulation of Notch and Delta: requirement for neuroblast segregation in Drosophila.

Segregation of a single neural precursor from each proneural cluster in Drosophila relies on Notch-mediated lateral signalling. Studies concerning the spacing of precursors for the microchaetes of the peripheral nervous system suggested the existence of a regulatory loop between Notch and its ligand Delta within each cell that is under transcriptional control. Activation of Notch leads to repression of the achaete-scute genes which themselves regulate transcription of Delta, perhaps directly. Here we have tested a requirement for transcriptional regulation of Notch and/or Delta during neuroblast segregation in embryos, by providing Notch and Delta ubiquitously at uniform levels. Neuroblast segregation occurs normally under conditions of uniform Notch expression. Under conditions of uniform Delta expression, a single neuroblast segregates from each proneural group in 80% of the cases, more than one in the remaining 20%. Thus transcriptional regulation of Delta is largely dispensable. We discuss the possibility that segregation of single precursors in the central nervous system may rely on a heterogeneous distribution of neural potential between different cells of the proneural group. Notch signalling would enable all cells to mutually repress each other and only a cell with an elevated neural potential could overcome this repression.

Animals↗
PubMed1975

Perturbation of mammalian cell division. II. Studies on the isolation and characterization of human mini segregant cells.

A method is described for the isolation, according to size, of mini segregants produced by the abnormal cleavage of reversibly arrested mitotic HeLa cells. Many of these mini segregants contain small amounts of DNA, as judged by Feulgen staining and chromosome analysis. After fusion with mitotic HeLa cells, the interphase chromosomes of the mini segregants are seen as either monovalent or bivalent prematurely condensed chromosomes (PCC), some of which are damaged. A proportion of isolated mini segregants synthesize DNA, RNA and protein. Fusion of mini segregants with interphase HeLa cells gives rise to cells with 'hybrid' karyotypes.

Cell Division↗
PubMed1990

Segregation of basic colors in an information display.

Previous studies of the role of color in visual search have shown efficient coding for as many as six colors in a high-density display. In an effort to increase this limit, we established an optimal basic color code from extensive surface-color-naming data. This code yielded excellent segregation in a visual search task: The time required to find a critical target of a cued color increased only marginally as up to nine groups of different colors were added to the display. It made no difference whether the cue was provided by name or by example. Significant color differences in this task triggered a second experiment, which examined the detectability of the critical target feature in the periphery. A close correlation was found to exist in the order of color performance between the two experiments. Color segregation was tested again in a third experiment, in which subjects were required to count the number of targets of the cued color. The colors again segregated well. A final experiment tested the proposition that it was the basic nature of the colors that was responsible for the good segregation. When seven basic colors were pitted against seven equally discriminable nonbasic ones in a modified version of the visual search task, no significant difference was found between the two groups. It is concluded that basic colors segregate well not because they are universally named but because they are well separated in color space.

Adult↗
PubMed2003

Segregation analysis of hepatocellular carcinoma in a moderately high-incidence area of East China.

AIM: To explore the mode of inheritance of hepatocellular carcinoma (HCC) in a moderately high-incidence area of East China. METHODS: A pedigree survey was conducted in 210 families (3315 individuals) ascertained through 210 HCC probands in Haimen, Jiangsu Province. Simple segregation analysis was conducted using SEGRANB software. The probability of ascertainment (pi), segregation ratio (p), and the proportion of sporadic cases (x) were estimated. Complex segregation analysis was performed using the REGTL program of S.A.G.E. Models were fitted on the data of 3212 individuals that allowed for personal HBsAg status and variable age of onset in REGTL program. RESULTS: The estimate of segregation ratio was 0.191 by SEGRANB. The probability of ascertainment was 0.0266, and the proportion of sporadic cases was 0.465. The results of complex segregation analysis showed that Mendelian autosomal recessive inheritance of a major gene that influenced the age of onset distribution of HCC, provided the best fit to the data. In the best-fitting recessive model, the frequency of the disease allele was 0.11138. HBsAg seropositive status would significantly increase the risk of developing HCC. CONCLUSION: These results suggest that at least one major gene is involved in the genetic predisposition to develop HCC at an earlier age of onset. The seropositive HBsAg status can significantly increase the risk of developing HCC, which provides strong support for the interaction between genetic and environmental risk factors.

Carcinoma, Hepatocellular↗
PubMed1989

Contrast and spatial variables in texture segregation: testing a simple spatial-frequency channels model.

Observers were shown patterns composed of two textures in which each texture contained two types of elements. The elements were arranged in a striped pattern in the top and bottom regions and in a checked pattern in the center region. Observers rated the degree to which the three regions were seen as distinct. When the elements were squares or lines, perceived segregation resulting from differences in element size could be canceled by differences in element contrast. Minimal perceived segregation occurred when the products of the area and the contrast (areal contrasts) of the elements were equal. This dependence of perceived segregation on the areal contrasts of the elements is consistent with a simple model based on the hypothesis that the perceived segregation of the regions is a function of their differential stimulation of spatial-frequency channels. Two aspects of the data were not consistent with quantitative predictions of the model. First, as the size difference between the large and small elements increased, the ratings at the point of minimum perceived segregation increased. Second, some effects of changing the fundamental frequency of the textures were not predicted by the model. These discrepancies may be explained by a more complex model in which a rectification or similar nonlinearity occurs between two stages of orientation- and spatial-frequency-selective linear filters.

Adult↗
PubMed2006

Segregation of HLA-C from ICAM-1 at NK cell immune synapses is controlled by its cell surface density.

NK cell activity is controlled by the integration of signals from numerous activating and inhibitory receptors at the immunological synapse (IS). However, the importance of segregation and patterning of proteins at the NK cell IS is unknown. In this study, we report that the level of expression of HLA-C on target cells determined its supramolecular organization and segregation from ICAM-1 at the NK cell IS, as well as its capacity to inhibit NK cell cytotoxicity. At YTS NK cell synapses formed with target cells expressing low levels of HLA-C (i.e., 10(4)/cell surface), a multifocal patterning of MHC class I protein predominated, whereas for higher levels of expression (10(5)/cell surface), clusters of HLA-C were more commonly homogeneous, ring-shaped, or containing multiple exclusions. This correlation of protein density with its patterning at the IS was independent of ATP- or actin-driven processes. Importantly, ICAM-1 and HLA-C segregated only at synapses involving target cells expressing high levels of MHC protein. For peripheral blood NK clones, there were specific thresholds in the level of target cell HLA-C needed to inhibit cytotoxicity and to cause segregation of HLA-C from ICAM-1 at the synapse. Thus, the synapse organization of HLA-C, determined by its level of expression, could directly influence NK cell inhibition, e.g., by regulating the proximity of activating and inhibitory receptors. For the first time, this suggests an important function for the assembly of an inhibitory NK cell IS. More broadly, segregation of proteins at intercellular contacts could transmit information about protein expression levels between cells.

Actins↗
PubMed1986

Segregation of HLA A,B haplotypes and the distribution of antigen mismatches between mother and offspring in Hutterite families.

Segregation of HLA haplotypes and offspring genotype distributions were analyzed in families from an inbred Caucasoid population, the Dariusleut Hutterite Brethren. Both parents and from one to 12 offspring were typed for HLA-A and -B antigens in 108 families. Segregation of paternal haplotypes was analyzed conditional on sibship size in 95 sibships (a total of 547 offspring), and segregation of maternal haplotypes, in 90 sibships (a total of 515 offspring). The distribution of the number of different genotypes among the offspring was analyzed conditional on sibship size in 90 families (515 offspring) where four equiprobable genotypes were expected. The distribution of the number of antigenic differences or mismatches for broad specificities between mother and offspring was analyzed in pooled family data consisting of a total of 377 offspring comprising 68 families. Compared with the multinomial distribution of segregation classes of haplotypes, there was no significant departure (probability .05 or less) from the expected segregation ratio for either paternal or maternal haplotypes. Compared with the multinomial distribution of the number of genotypes among the offspring, only two of the 11 sibship sizes had configurations that exceeded the 5% level of significance. Given the number of statistical tests performed, it is likely that these results could be explained by chance variation. Finally, there was no relative deficiency of offspring who were less mismatched with their mother for HLA-A and -B broad specificities. Therefore, if HLA-A,B region variation does have a major effect on the differential survival of fetuses in some families, it is an uncommon factor among fertile couples from this inbred population.

Alberta↗
PubMed1986

Reciprocal translocations between acrocentrics: segregational analysis in twenty-nine families with unbalanced progeny.

This study comprises 29 families with 42 unbalanced offspring in which reciprocal interacrocentric translocations (RIATs) were identified by banding. The observed unbalances were due to adjacent-1 (42.9%), adjacent-2 (28.6%) and 3:1 (28.6%) segregations. The concordance between the observed and expected segregations was 85.7% according to the Jalbert et al. (1980) criteria. 17.2% of the RIATs led to unbalances by 2 different segregations. 78.6% of the cases were maternal in origin. The overall incidence of spontaneous abortion was 37%. Corrected recurrence risks of unbalanced liveborn offspring for female and male carriers were seemingly similar: 17.8% and 12.5% respectively. These data indicate that RIATS exhibit (as distinctive features) an approximate 4:3:3 ratio for adjacent-1, adjacent-2 and 3:1 segregations, and a proneness to produce unbalances by different segregations.

Abortion, Spontaneous↗
PubMed1984

Sample-size calculations in segregation analysis.

Segregation analysis, employing nuclear families, is the most frequently used method to evaluate the mode of inheritance of a trait. To our knowledge, there exists no tabular information regarding the sample sizes required of individuals and families needed to perform a significance test of a specific segregation ratio for a predetermined power and significance level. To fill this gap, we have developed sample-size tables based on the asymptotic variance of the maximum likelihood estimate of the segregation ratio and on the normal approximation for two-sided hypothesis testing. Assuming homogeneous sibship size, minimum sample sizes were determined for testing the null hypothesis for the segregation ratio of 1/4 or 1/2 vs. alternative values of .05-.80, for the significance level of .05 and power of .8, for ascertainment probabilities of nearly 0 to 1.0, and sibship sizes 2-7. The results of these calculations indicate a complex interaction of the null and the alternate hypotheses, ascertainment probability, and sibship size in determining the sample size required for simple segregation analysis. The accompanying tables should aid in the appropriate design and cost assessment of future genetic epidemiologic studies.

Epidemiologic Methods↗
PubMedDate not supplied

[Spatial segregation of old people in West German cities].

The presented segregation analysis of the spatial segregation of the aged produces differentiated segregation data of eight large cities of the Federal Republic of Germany for the first time. The investigations confirms the hypothesis that people who are older than 65 are the mostly segregated age group of the population. There is a trend of a longitudinal rising of segregation between 1950 and 1970. The registered high concentration of old people of lower SES in renovation-needy town areas underlines an actual important problem of town-planning politics.

Adolescent↗
PubMed1976

Segregation of Col Ib and drd7 into minicells.

The wild-type plasmid ColIb and its mutant drd7 derepressed in conjugation were transferred to Escherichia coli K12 P678-54 which produces minicells. Fertility functions of drd7 remained derepressed in the new host. P678-54drd7 transmitted the plasmid at a high frequency (28.6%) and it was effectively lysed by the phage If1. Significant amounts of 3H-DNA segregated from P67854Col+ into minicells dependent upon the presence of the plasmid. The depressed plasmid segregated more effectively into minicells than the wild-type plasmid. ColIb segregated into 2% whereas ColIbdrd7 into 8.4% of minicells. The difference in the frequency of segregation of the wild-type and the derepressed plasmid indicated different cell membrane attachment sites of each plasmid studied. Mini-drd7 were able to transfer the plasmid to E. coli Row at a low frequency (0.1%). Minicells carrying either of plasmid were capable to synthesize RNA and protein. RNA and protein synthesis were plasmid specific and the precursors were not incorporated into minicells without plasmids. Rifampin and chloramphenicol inhibited RNA and protein synthesis in minicells, respectively. The more effective incorporation of 3H-uridine or 14C-leucine into minicells harboring drd7 than ColIb resulted presumably from the high efficiency of the segregation of drd7 into minicells. Polyacrylamide gel electrophoresis of 3H-RNA has shown that plasmids in minicells were able to code low molecular RNA of 4s. No 16 or 23 ribosomal RNA was found in the profiles of de novo synthesized RNA in minicells.

Bacterial Proteins↗
PubMed1996

Analysis of meiotic segregation, using single-sperm typing: meiotic drive at the myotonic dystrophy locus.

Meiotic drive at the myotonic dystrophy (DM) locus has recently been suggested as being responsible for maintaining the frequency, in the human population, of DM chromosomes capable of expansion to the disease state. In order to test this hypothesis, we have studied samples of single sperm from three individuals heterozygous at the DM locus, each with one allele larger and one allele smaller than 19 CTG repeats. To guard against the possible problem of differential PCR amplification rates based on the lengths of the alleles, the sperm were also typed at another closely linked marker whose allele size was unrelated to the allele size at the DM locus. Using statistical models specifically designed to study single-sperm segregation data, we find no evidence of meiotic segregation distortion. The upper limit of the two-sided 95% confidence interval for the estimate of the common segregation probability for the three donors is at or below .515 for all models considered, and no statistically significant difference from .5 is detected in any of the models. This suggests that any greater amount of segregation distortion at the myotonic dystrophy locus must result from events following sperm ejaculation. The mathematical models developed make it possible to study segregation distortion with high resolution by using sperm-typing data from any locus.

Adult↗
PubMed1996

Characterization of new vacuolar segregation mutants, isolated by screening for loss of proteinase B self-activation.

Part of the vacuole in the mother cell of Saccharomyces cerevisiae is segregated early in the cell cycle to establish a new vacuole in the bud. Investigation of the molecular mechanism of vacuolar segregation has previously been limited by the lack of an efficient screen for mutants defective in this process. We developed a new screening procedure based on a cascade for activation of vacuolar proteases. Carboxypeptidase Y (CPY) is activated by proteinase A (PrA). However, upon PrA depletion, CPY continues to be activated, supposedly by self-sustaining proteinase B (PrB) activity that is transferred from one generation to the next generation through vacuolar segregation. In this study fourteen mutants were isolated that failed to sustain CPY activation upon PrA depletion. While these mutants had altered vacuolar protease-activity levels, two mutants showed specific vacuolar segregation defects. They formed large-budded cells that contained no vacuole or extremely small vacuoles in the bud. These mutants represented two complementation groups, named VAC6 and VAC7. The data indicate that constitutive vacuolar segregation mutants are viable, but that they are unable to transfer proteolytic activities from mother vacuole to the bud. Surprisingly, despite the apparent lack of quantitative vacuolar inheritance, all daughter cells of vac6 and vac7 had obtained a vacuole before cell division.

Aspartic Acid Endopeptidases↗
PubMed2004

Segregation analysis of bronchial hyperresponsiveness in a general population in north Italy.

Bronchial hyperresponsiveness (BHR) is an intermediate phenotype of asthma, with a heritability component of 30-67% and possible linkage to regions on chromosome arms 5q, 11q, and 20p. Familial correlation analysis and segregation analysis for BHR, using the FCOR and REGC programs of the S.A.G.E package, were performed to examine inheritance patterns of BHR in a general population of 1167 subjects in 550 families from the Po River Delta. BHR was assessed using the log(10) of the slope of the methacholine dose-response curve (log slope) for each subject who met inclusion criteria. Using multiple linear regression analysis, the log slope values were adjusted for age, age(2), sex, and height, and used in the familial correlation and segregation analyses. Father-offspring correlations are statistically significant, due specifically to high father-son correlations (r = 0.296, P < 0.001, adjusted values). Segregation analysis of BHR in the overall population, with and without a smoking covariate (number of packyears smoked), indicates an apparent absence of genetic transmission within families. However, in a segregation analysis of BHR in smoking families only, after adjusting for number of packyears smoked, the Mendelian transmission models could not be rejected. This may be evidence of a gene by smoking effect, and suggests that in families of smokers, a single locus gene may in part explain the inheritance of a compound phenotype (BHR x packyears).

Adult↗
PubMed2005

Unequal segregation of parental chromosomes in embryonic stem cell hybrids.

Chromosome segregation was studied in 14 intra- and 20 inter-specific hybrid clones generated by fusion of Mus musculus embryonic stem (ES) cells with fibroblasts or splenocytes of DD/c mice or Mus caroli. As a control for in vitro evolution of tetraploid karyotype we used a set of hybrid clones obtained by fusion of ES cells (D3) with ES cells (TgTP6.3). Identification of the parental chromosomes in the clones was performed by microsatellite analysis and in situ hybridization with labeled species-specific probes. Both analyses have revealed three types of clones: (i) stable tetraploid, observed only for ES x ES cell hybrids; (ii) bilateral loss of chromosomes of both ES and somatic partners; (iii) unilateral segregation of chromosomes of the somatic partner. Observed unilateral segregation was extensive in ES-splenocyte cell hybrids, but lower in ES-fibroblast hybrid clones. Developmental state of the somatic partner is presumably responsible for directional chromosome loss. Nonrandom segregation implies that initial differences in the parental homologous chromosomes were not immediately equalized implying at least transient persistence of the differentiated epigenotype.

Animals↗