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PubMed2000

Segregation analysis of serum uric acid in the NHLBI Family Heart Study.

Segregation analysis was performed on the serum uric acid measurements from 523 randomly ascertained Caucasian families from the NHLBI Family Heart Study. Gender-specific standardized residuals were used as the phenotypic variable in both familial correlation and segregation analysis. Uric acid residuals were adjusted for age, age2, age3, body mass index (kg/m2), creatinine level, aspirin use (yes/no), total drinks (per week), HOMA insulin resistance index [(glucose * insulin)/22.5], diuretic use (yes/no), and triglyceride level. Sibling correlations (r=0.193) and parent-offspring correlations (r=0.217) were significantly different from zero, but these two familial correlations were not significantly different from one another. After adjustment for covariates, the heritability estimate for serum uric acid was 0.399. Segregation analysis rejected the "no major gene" model but was unable to discriminate between an "environmental" and a "Mendelian major gene" model. These results support the hypothesis that uric acid is a multifactorial trait possibly influenced by more than one major gene, modifying genes, and environmental factors.

Arteriosclerosis↗
PubMed2000

MtDNA substitution rate and segregation of heteroplasmy in coding and noncoding regions.

The mitochondrial DNA (mtDNA) substitution rate and segregation of heteroplasmy were studied for the non-coding control region (D-loop) and 500 bp of the coding region between nucleotide positions 5550 and 6050, by sequence analysis of blood samples from 194 individuals, representing 33 maternal lineages. No homoplasmic nucleotide substitutions were detected in a total of 292 transmissions. The estimated substitution rate per nucleotide per million years for the control region (micro>0.21, 95% CI 0-0.6) was not significantly different from that for the coding region (micro>0.54, 95% CI 0-1.0). Variation in the length of homopolymeric C streches was observed at three sites in the control region (positions 65, 309 and 16,189), all of which were in the heteroplasmic state. Segregation of heteroplasmic genotypes between generations was observed in several maternal pedigrees. At position 309, a longer poly C tract length was strongly associated with a higher probability for heteroplasmy and rapid segregation between generations. The length heteroplasmy at positions 65 and 16,189 was found at low frequency and was confined to a few families.

Alleles↗
PubMed1998

Inheritance of chronic tension-type headache investigated by complex segregation analysis.

We investigated the mode of inheritance of chronic tension-type headache in 122 families. The probands were from the Copenhagen Headache Clinic, Denmark. The criteria of the International Headache Society were used. The patterns of segregation of chronic tension-type headache were assessed by complex segregation analysis performed with the computer program POINTER. Of the 122 probands with chronic tension-type headache, 56 had 71 first-degree relatives with chronic tension-type headache. The complex segregation analysis indicates that chronic tension-type headache has multifactorial inheritance.

Age Factors↗
PubMed1999

Analysis of segregation and aneuploidy in two reciprocal translocation carriers, t(3;9)(q26.2;q32) and t(3;9)(p25;q32), by triple-color fluorescence in situ hybridization.

Meiotic segregation patterns of chromosomes 3 and 9 were analyzed in sperm of two translocation carriers (t(3;9)(q26.2;q32) and t(3;9)(p25;q32)) by triple-color fluorescent in situ hybridization (FISH) with a telomeric DNA probe in addition to two centromeric probes. The frequencies of each sperm product resulting from alternate or adjacent I, adjacent II and 3:1 segregation in a t(3;9)(q26.2;q32) translocation carrier were 88.35%, 5.44% and 5.94%, respectively. On the other hand, the frequencies of each sperm product in a t(3;9)(p25;q32) translocation carrier were 89.23%, 6.02% and 4.48%, respectively. Of all the sperm products, the frequency of normal or chromosomally balanced sperm in a t(3;9)(q26.2;q32) and a t(3;9)(p25;q32) were 52.49% and 47.25%, respectively. The frequencies of each sperm product resulting from various segregations were different between both carriers and significantly deviated from the expected frequencies. Additional dual-color and triple-color FISH were performed to analyze aneuploidy rates for chromosomes 12, 17, 18, X and Y in order to detect any interchromosomal effect; no evidence of an interchromosomal effect was found.

Abortion, Habitual↗
PubMed2006

The role of foraging behaviour in the sexual segregation of the African elephant.

Elephants (Loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. Body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whilst having lower mass-specific energy requirements. We test two distinct theories: the scramble competition hypothesis (SCH) and the forage selection hypothesis (FSH). Comprehensive behavioural data were collected from the Pongola Game Reserve and the Phinda Private Game Reserve in South Africa over a 2.5-year period. The data were analysed using sex as the independent variable. Adult females targeted a wider range of species, adopted a more selective foraging approach and exhibited greater bite rates as predicted by the body size hypothesis and the increased demands of reproductive investment (lactation and pregnancy). Males had longer feeding bouts, displayed significantly more destructive behaviour (31% of observations, 11% for females) and ingested greater quantities of forage during each feeding bout. The independent ranging behaviour of adult males enables them to have longer foraging bouts as they experience fewer social constraints than females. The SCH was rejected as a cause of sexual segregation due to the relative abundance of low quality forage, and the fact that feeding heights were similar for both males and females. However, we conclude that the differences in the foraging strategies of the sexes are sufficient to cause spatial segregation as postulated by the FSH. Sexual dimorphism and the associated behavioural differences have important implications for the management and conservation of elephant and other dimorphic species, with the sexes effectively acting as distinct "ecological species".

Animals↗
PubMed2000

Spectral contrasts underlying auditory stream segregation in goldfish (Carassius auratus).

This study investigates the effects of spectral separation of sounds on the ability of goldfish to acquire independent information about two simultaneous complex sources. Goldfish were conditioned to a complex sound made up of two sets of repeated acoustic pulses: a high-frequency pulse with a spectral envelope centered at 625 Hz, and a low-frequency pulse type centered at 240, 305, 390, or 500 Hz. The pulses were presented with each pulse type alternating with an overall pulse repetition rate of 40 pulses per second (pps), and a 20-pps rate between identical pulses. Two control groups were conditioned to the 625-Hz pulse alone, repeated at 40 and 20 pps, respectively. All groups were tested for generalization to the 625-Hz pulse repeated alone at several rates. If the two pulse types in the complex resulted in independent auditory streams, the animals were expected to generalize to the 625-Hz pulse trains as if they were repeated at 20 pps during conditioning. It was hypothesized that as the center frequency of the low-frequency pulse approached that of the 625-Hz pulse, the alternating trains would be perceived as a single auditory stream with a repetition rate of 40 pps. The group conditioned to alternating 625- and 240-Hz pulses generalized least, with maximum generalization at 20 Hz, suggesting that the animals formed at least one perceptual stream with a repetition rate of 20 pps. The other alternating pulse groups generalized to intermediate degrees. Goldfish can segregate at least one "auditory stream" from a complex mixture of sources. Segregation can be based on spectral envelope and grows more robust with growing spectral separation between the simultaneous sources. Auditory stream segregation and auditory scene analysis are shared among human listeners, European starlings, and goldfish, and may be primitive characteristics of the vertebrate sense of hearing.

Acoustic Stimulation↗
PubMed2006

High genetic variability of the Streptococcus thermophilus cse central part, a repeat rich region required for full cell segregation activity.

The cse gene of Streptococcus thermophilus encodes an extracytoplasmic protein involved in cell segregation. The Cse protein consists of two putative domains: a cell wall attachment LysM domain and a catalytic CHAP domain. These two domains are spaced by an interdomain linker, known as Var-Cse, previously reported to be highly divergent between two S. thermophilus strains. The aim of this study was to assess the extent of this intraspecific variability and the functional involvement of the var-cse region in cell segregation. Analysis of the var-cse sequence of 19 different strains allowed detection of 11 different alleles, varying from 390 bp to 543 bp, all containing interspersed and tandem nucleotides repeats. Overall, 11 different repeat units were identified and some series of these small repeats, named supermotifs, form large repeats. Results suggested that var-cse evolved by deletion of all or part of the repeats and by duplication of repeats or supermotifs. Moreover, sequence analysis of the whole cse locus revealed that the cse ORF is mosaic suggesting that var-cse polymorphism resulted from horizontal transfer. The partial deletion of the var-cse region of the S. thermophilus strain CNRZ368 led to the lengthening of the number of cells per streptococcal chain, indicating that this region is required for full cell segregation in S. thermophilus strain CNRZ368.

Alleles↗
PubMed2000

Familial Aggregation and Segregation Analysis of Snoring and Symptoms of Obstructive Sleep Apnea.

To investigate possible modes of inheritance that would explain familial aggregation in obstructive sleep apnea (OSA), familial correlation and segregation analyses were performed on data derived from 584 pedigrees with 2019 cases enrolled in the Tucson Epidemiologic Study of Obstructive Airways Disease (TESOAD) who were at least 10 years of age and who had information pertaining to snoring and daytime sleepiness. Data were obtained from the 9th (May 1984 to October 1985) and 12th (February 1990 to October 1992) surveys of the TESOAD, which is a random, stratified sample of the non-Hispanic Caucasian population of Tucson, Arizona. A snoring phenotype was considered present if it occurred on at least some nights. A "sleep apnea" phenotype was constructed if participants snored and experienced daytime sleepiness. Familial correlations for snoring showed significant mother-child and sibling correlations but not father-child correlations. For sleep apnea, significant parent-daughter but not parent-son or sibling correlations were observed. Segregation analyses for snoring with regressive familial effects and sibling, age, and obesity covariates showed no evidence for mendelian transmission. However, additional familial effects were present that suggested phenotype aggregation from polygenic or environmental factors, or both. For the sleep apnea phenotype, similar segregation analyses indicated that mendelian dominant or codominant models were possible. However, the analyses also suggested that a nongenetic model fit the data as well. In addition, consistent with the familial correlations, specific maternal- and sibling-related effects remained even after inclusion of age, gender, and obesity covariates. These data support the concept that inheritable or shared environmental factors contribute to the development of OSA and that maternal components may be more important than paternal ones.

Journal Article↗
PubMed1987

Receptors for transferrin and transcobalamin II display segregated distribution on microvilli of leukemia L1210 cells.

Simultaneous addition of uniform latex particles derivatized with transferrin (0.532 micron) and transcobalamin II (0.345 micron) to leukemia L1210 cells resulted in segregated binding to individual microvilli as demonstrated by scanning electron microscopy. This segregated distribution suggests that individual microvilli are endowed either transferrin or transcobalamin II receptors but not both. Intracellular sorting and segregation of newly synthesized or recycling receptors probably occur prior to expression on the plasmalemma microvilli.

Animals↗
PubMed1984

Regional water changes during oocyte meiotic maturation: evidence of ooplasmic segregation.

Cryomicrodissection was used to measure the intraoocytic distribution of water before and during meiotic maturation in Rana pipiens oocytes. Animal ooplasm contained about 10% more water in matured than in ovarian oocytes. The increase was not dependent on the uptake of extracellular water, occurring even when oocytes were matured in a paraffin oil medium. Rather, animal ooplasm hydration appeared to be due to an increase in the volume fraction occupied by cytoplasm (reduced yolk density) through: (1) migration of cytoplasm from the vegetal to animal hemisphere and (2) mixing of ooplasm with nuclear sap during germinal vesicle breakdown (GVBD). Cytoplasmic migration (or ooplasmic segregation) began prior to GVBD, probably within an hour of exposure to progesterone and appeared to continue through the period of GVBD. The volume of cytoplasm that moved significantly reduced water concentrations in vegetal ooplasm at 6 hr postprogesterone and offset any subsequent water gain due to the mixing of nuclear sap and vegetal ooplasm at GVBD. The findings suggest that segregational movements are among the early maturational changes entrained by progesterone. Ooplasmic segregation is considered in the context of theories of cytomatrix movement in which control resides in regional Ca2+ activity gradients. We address the problem of the vegetal----animal directionality of movement and suggest that the annulate lamellae play a role.

Animals↗
PubMed1991

Segregation of Na(+)-channel gene expression during neuronal-glial branching of a rat PNS-derived stem cell line, RT4-AC.

RT4 is a family of cell lines isolated from an ethylnitrosourea-induced rat peripheral neurotumor. RT4-AC cells express both excitable membrane and glial cell properties. In a process called cell-type conversion, RT4-AC cells segregate these properties to generate three distinct derivative cell types which have been classified as either neuronal (RT4-E and RT4-B) or glial (RT4-D). In this report we demonstrate that: (1) upon cell-type conversion, Na(+)-channel mRNA expression segregates primarily with the RT4 neuronal derivatives, (2) the SkM2 Na(+)-channel gene, which was originally isolated from rat muscle cDNA libraries, is the predominant gene expressed by the RT4 neuronal derivatives, (3) the three rat brain Na(+)-channel genes I, II, and III and the muscle-derived SkM1 gene are not the principal Na(+)-channel genes involved in the segregation, although very low levels of message of these genes are detected, and (4) the RT4 glial derivative expresses slightly higher levels of message from rat brain genes I and II than the neuronal derivatives. Since the RT4 cell lines were derived from a peripheral neurotumor these results present the possibility that the SkM2 gene may be important in vivo in the rat peripheral nervous system.

Animals↗
PubMed1989

Dominance and independent segregation of metabolic cooperation-competence and pluripotency in an embryonal carcinoma cell hybrid.

We report the isolation of a fusion hybrid, PR3, from a pluripotent embryonal carcinoma (EC) cell line, PSA4, which is metabolic cooperation-competent, and an EC line R5/3OA which has a reduced capacity for metabolic cooperation and a restricted developmental capacity. PR3 resembles its pluripotent parent PSA4 in its capacity for gap-junction-mediated transfer of uridine nucleotides and in its pluripotency both in embryoid bodies in vitro and in tumors in vivo. This enabled the relationship between pluripotency and metabolic cooperation to be examined by the selection of segregant lines. Cooperation-deficient lines were isolated from a thioguanine-resistant intermediate line (PR3Tg12) using "Kiss of Death" selection. A novel method was devised for the selection of differentiation-deficient segregants using feeder cell-conditioned medium which partially inhibits in vitro differentiation. It was found that communication-competence and in vitro pluripotency segregated independently, demonstrating that the loss of developmental capacity in R5/3OA cannot be attributed to its communication-deficiency.

Animals↗
PubMed1987

Mechanism for chromosome and minichromosome segregation in Escherichia coli.

A mechanism for the segregation of chromosomes and minichromosomes into daughter cells during division of Escherichia coli is presented. It is based on the idea that the cell envelope contains a large number of sites capable of binding to the chromosomal replication origin, oriC, and that a polymerizing DNA strand becomes attached to one of the sites at initiation of a round of replication. The attachment sites are distributed throughout the actively growing cell envelope, i.e. lateral envelope and septum, but not in the existing cell poles. This asymmetric distribution of oriC attachment sites accounts for the experimentally observed non-random chromosome and minichromosome segregation, and for the variation in the degree of non-random segregation with cell strain and growth rate. The multi-site attachment concept also accounts for the unstable maintenance of minichromosomes.

Cell Division↗
PubMed1989

Segregation and linkage analyses of bipolar and major depressive illnesses in multigenerational pedigrees.

Data were collected on six large multigenerational pedigrees, four ascertained through a proband with major depression and two ascertained through a proband with a bipolar form of illness. Diagnoses were made using the SADS-L structured interview and Research Diagnostic Criteria (RDC). Complex segregation analyses were conducted on the bipolar and the major depression pedigree sets using a model allowing for both major locus and polygenic inheritance; in these analyses a variety of diagnostic schemes and assumptions concerning the lifetime population prevalence were examined. Linkage analyses on standard markers were conducted using parameters for transmission of susceptibility to illness derived from the segregation analyses. Results of the segregation analyses were quite sensitive to the diagnostic and prevalence assumptions. In the pedigrees ascertained through probands with a bipolar form of illness, we were unable to discriminate between major gene and polygenic inheritance. The data were compatible with Mendelian major gene transmission of susceptibility to illness when bipolar and schizoaffective manic diagnoses were considered as affected and the lifetime population prevalence was between 0.04 and 0.06. Outside this narrow prevalence range, or when additional diagnoses, such as major depression or hypomania, were included as expressions of liability to disease, major gene transmission of susceptibility to disease could be rejected. Similarly, in the pedigrees ascertained through probands with major depression, it was not generally possible to discriminate between major gene and polygenic transmission of susceptibility to illness. For a diagnostic scheme including only major depression as a manifestation of susceptibility to illness, there was a narrow range of lifetime population prevalence values (female prevalence ranging from 0.20 to 0.25, male prevalence set to 1/2 female prevalence) which yielded results compatible with major gene transmission. Linkage analyses for all markers yielded negative or inconclusive results. In one bipolar pedigree a lod score of 1.65 was found with a marker in chromosome 1 recommending further studies of this chromosome.

Adult↗
PubMed1983

Assortative mating and the segregation variance.

Feldman and Cavalli-Sforza (Theoret. Pop. Biol. (1979), 15, 276-307; (1981), 19, 370-377) have emphasized the role of the segregation variance in models of assortative mating for continuous characters. This note examines its behavior in the context of a general additive model. Using known results concerning the effects of assortative mating and selection on genic variance and correlations among uniting gametes it is shown that the effects of these processes on segregation variance wil be small if the effective number of loci is large. Thus models in which the segregation variance remains constant are approximate descriptions of the behavior of characters determined by many loci.

Analysis of Variance↗
PubMed1982

Does segregation of differently moving areas depend on relative or absolute displacement?

We have examined the occurrence of segregation in random dot kinematograms in which a central patch of dots, and the surrounding area, were each coherently displaced, either in the same or opposite directions (Fig. 1), by varying amounts. The limiting displacement for segregation to occur is determined primarily by the displacement of each region alone, rather than the relative displacement of neighbouring regions (Fig 2). We conclude that the "correspondence problem" is solved by means of a short range motion detection process acting on each region separately; segregation is achieved by comparing the results of this process for adjacent regions.

Form Perception↗
PubMed1992

Texture segregation is processed by primary visual cortex in man and monkey. Evidence from VEP experiments.

We investigated whether the process of texture segregation can be allocated to a specific visual cortical area. We designed a stimulus to reveal the presence of a mechanism, which is specifically sensitive to a checkerboard, that is solely defined by textures segregating due to orientation differences of the constituting line segments. We recorded evoked potentials to this stimulus in man and awake monkey. A difference component, signalling texture segregation sensitivity, could be recorded from both types of subjects. Its presence depended on the spatial extent of the textures, in a manner correlating with the perceptibility of the checkerboard. This difference response could be localized in primary visual cortex by means of equivalent dipole estimations.

Animals↗
PubMed1992

Segregation of mesh-derived textures evaluated by resistance to added disorder.

In the "figure detection task" the strength of segregation for a particular texture pair was estimated by the threshold amount of added disorder that prevented segregation of a textured figure from a textured ground. Disorder was either jitter in the orientation of the texture elements, or jitter in their xy positions, or a mixture of the two. Other procedures included lowpass filtering, and a task requiring discrimination between textured figures of different shapes. Orientation cues are weakly or inconsistently used for segregating mesh textures. The low spatial harmonics are very important. A new finding is that orientation and position jitter thresholds for a set of figure/ground texture patterns are often proportional. In a mixture the one disorder can be exchanged for the other.

Discrimination, Psychological↗