bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clustering of high density lipoprotein cholesterol levels in premenopausal and postmenopausal female twins
Authors: Harris Emily L. , Falk Roni T. , Goldstein Alisa M. , Park Lawrence P. 
Published: June 2005

AbstractPrevious family and twin studies indicate that genetic variation makes an important contribution to individual variation in high density lipoprotein cholesterol (HDL) levels, even after adjustment for covariates (such as obesity and alcohol consumption) that also cluster in families. However, most studies assume that genetic mechanisms affecting variation in HDL level are the same in all subgroups of the population (e.g., men versus women, by age). Using data from the Kaiser‐Permanente Women Twins Study, we found different patterns of clustering for monozygotic (MZ) and dizygotic (DZ) twins depending on menopausal status. Premenopausal MZ twins were more similar than postmenopausal MZ twins (ri = 0.79 and ri = 0.61, respectively, after adjustment for age, alcohol consumption, smoking status, degree of obesity, and leisure‐time exercise); premenopausal and postmenopausal DZ twins were alike to the same extent (ri = 0.31 and ri = 0.32, respectively, adjusted as above). These data suggest that either postmenopausal MZ twins have a greater degree of shared environment than postmenopausal DZ twins (e.g., postmenopausal female hormone use) or that genetic mechanisms that affect individual variation in HDL level differ in pre‐ and postmenopausal women. Data were not available on postmenopausal female hormone use. If genetic mechanisms that influence variation in HDL levels differ between pre‐ and postmenopausal women, genetic epidemiologic methods that assume that genetic and environmental sources of variation are the same for all groups of individuals may lead to false conclusions. © 1993 Wiley‐Liss, Inc.
A genetic analysis of cardiovascular disease risk factor clustering in adult female twins
Authors: Mosteller M. 
Published: June 2005

AbstractRisk factors for cardiovascular disease have been shown to cluster in adult populations of men and women [Criqui et al., 1980]. In a population of adult female twin pairs (ages 18–85), body mass index, systolic and diastolic blood pressure, and high and low density lipoprotein levels were found to exhibit significant clustering. Path analysis was used to resolve the risk factor correlations into genetic, environmental, and age‐related components. © 1993 Wiley‐Liss, Inc.
Effect of ignoring genotype‐environment interaction on segregation analysis of quantitative traits
Authors: Tiret Laurence , Abel Laurent , Rakotovao Roger 
Published: June 2005

AbstractThirty replicates of 200 nuclear families (6 members each) were generated under three GxE interaction models. Segregation analyses of these data were performed using a regressive model taking into account an interaction effect or not. Results showed that ignoring the GxE interaction markedly decreased the power for accepting a major gene and led to serious bias in parameter estimates. © 1993 Wiley‐Liss, Inc.
Use of the regressive models in linkage analysis of quantitative traits
Authors: Demenais Florence , Lathrop Mark 
Published: June 2005

AbstractUse of the regressive models to account for residual familial correlations in linkage analysis of complex quantitative traits can increase the power to detect linkage. This is especially observed when the effect of the gene to be mapped is small or when the residual correlations are substantial. © 1993 Wiley‐Liss, Inc.
Two‐locus and bivariate segregation analysis of HDL‐C and apo AI
Authors: Xu J. F. , Prenger V. L. , Coresh J. , Beaty T. H. 
Published: June 2005

AbstractTwo‐locus and bivariate segregation analyses of HDL‐C and apo AI were carried out using the GAW8 Berkeley data set. For HDL‐C, results are ambiguous. Both the mixed environmental model and the mixed Mendelian model fit the data equally well. For apo AI, however, univariate one‐locus segregation analysis suggests a Mendelian major gene controlling its levels. Moreover, two‐locus analysis suggests a second major gene is involved. Bivariate segregation analysis indicates these data cannot resolve the question as to whether a single Mendelian major gene with pleiotropic effects controls levels of both HDL‐C and apo AI in humans. © 1993 Wiley‐Liss, Inc.
Segregation analysis under an alternative formulation for the mixed model
Authors: Stricker C. , Fernando R. L. , Elston R. C. 
Published: June 2005

AbstractDifferent approaches for segregation analysis that have been proposed in the past are compared to a new approach by Fernando et al. [submitted], the finite polygenic mixed model, analyzing a real and a simulated data set. © 1993 Wiley‐Liss, Inc.
Segregation analysis of diastolic blood pressure in a large pedigree
Authors: Weissbecker Karen A. 
Published: June 2005

AbstractHypertension, a major risk factor for cardiovascular diseases, is thought to be inherited to some extent. However, the nature of its genetic component remains unresolved. In the present study, data from a single large kindred (the HGAR1 pedigree) were used to search for evidence of single gene and multifactorial effects on diastolic blood pressure. Commingling analyses found that a mixture of three distributions fit the data significantly better than a single normal distribution, suggesting a major effect influencing diastolic blood pressure levels. However, segregation analysis, using regressive models, indicated that the transmission probabilities were not consistent with Mendelian expectations. There was no evidence of either major gene or polygenic effects on diastolic blood pressure levels in this family. © 1993 Wiley‐Liss, Inc.
The ontogeny of sperm specific lactate dehydrogenase in mice
Authors: Goldberg Erwin , Hawtrey Christopher 
Published: June 2005

AbstractTestes of sexually mature mice (Mus musculus) contain a unique lactate dehydrogenase isozyme associated with the spermatozoan cell. This isozyme differs in subunit composition and reactivity to the substrate DL‐α‐hydroxyvalerate when compared to the usual five isozymes found in other tissues. It has been termed LDH‐X and has the same mobility as LDH‐5 when subjected to electrophoresis on standard polyacrylamide gels. This enzyme first appears during development at the time spermatocytes first mature in the testes.From the time of birth until sexual maturity is reached the specific activity of LDH in testes extracts does not change appreciably. When the mice have reached the weight of 6.5 to 7.5 g with a testes weight of 20 mg, which is equivalent to an age of 15 to 17 days postpartum, LDH‐X appears. It is at approximately this time that the first differentiative division of the primitive germ cell, the spermatogonium, occurs. For the next period of time, 15–20 days, the testes grow and differentiate at a rapid rate and during this same period the specific activity of the sperm LDH also increses.Histochemical evidence indicated that activity of LDH‐1, 2, and 3 is highest in the interstitial cells while LDH‐X activity is restricted to the cells that are close to the lumen of the testicular tubule.
Cell mobility in fused homo‐ and heteronomic tissue fragments
Authors: Weston J. A. , Abercrombie M. 
Published: June 2005

AbstractIf specific reorganization in fused heteronomic tissue fragments results from the movements of individual cells, this mobility should also promote intermingling of cells at the boundary between fused tissue fragments. To test this, tritiated‐thymidine labeled embryonic heart and liver fragments were fused in heteronomic and homonomic combinations with unlabeld heart and liver tissue, and maintained in vitro up to 48 hours after fusion. Radioautographs revealed that tissue reorganization occurred in heteronomic combinations in shaker culture, but intermingling of cells at the border between labeled and unlabeled fragments was negligible in both heteronomic and homonomic fusions. It is concluded that individual cells are probably not freely motile within intact tissue. This conclusion supports the predictions based on the hypothesis of “contact inhibition” of cell movement.The characteristic tissue reorganization in heteronomic combinations, at least for intact heart and liver tissue, is presumed to result from the spreading of stable adhesions of cellular pseudopodial extensions rather than from the free locomotion of individual cells. The spreading of one tissue over another during reorganization seems to be counteracted by weak adhesions to substrates since heteronomic fusions allowed to remain on agar or Millipore filter substrates do not reorganize.
Some properties of a macromolecular extract producing developmental arrest of injected embryos (Rana pipiens)
Authors: Melton Charles G. , Kimmel Donald L. 
Published: June 2005

AbstractSeveral molecular species, suspected of being responsible for the blastular arrest that follows injection of adult liver extracts into Rana pipiens zygotes, were investigated by biochemical assays of the extracts, by injection of the extracts after removal of these molecular species, and/or by injection of these species themselves into zygotes. Negative results have ruled out, with varying degrees of certainty, DNA, RNA, basic protein, polysaccharide, neutral protase, ribonuclease, phosphodiesterase I, and two varieties of deoxyribonuclease (DNase). The arrest‐producing component is tentatively identified as a non‐basic protein, although the evidence is not yet conclusive.Injected neutral DNase (± trypsin) failed to produce either consistent arrest or embryonic chromosomal abnormalities. A review of the literature on DNase effects in vivo also revealed no clear precedent indicating that arrest can be attributed to derangement of the embryonic chromosomes by a DNase in the extracts.
Isolation of planarian neoblasts and their behavior in Vitro with some aspects of the mechanism of the formation of regeneration blastema
Authors: Betchaku Teiichi 
Published: June 2005

AbstractA method of isolating neoblasts from Dugesia dorotocephala and the process of their aggregation in vitro are described. Morphology and behavior of gastrodermal cells and fixed parenchyma cells in vitro are also reported. Basically the neoblast is an oval cell with a large primary process and a finer secondary process at the opposite pole. Neoblasts have strong mutual affinity and very little affinity with other types of cells. The only observed method of locomotion of neoblasts in vitro was the contraction of the firmly attached primary processes between two or more neoblasts, which ends in their aggregation. Gastrodermal cells and fixed parenchyma cells are the most active migratory cells in vitro. With the observation of the cell movement both in vitro and in the fragments of the body, it was concluded that the primary accumulation of neoblasts at the open wound is not due to the active migration of neoblasts from the intact region as surmised by some other authors but due to the aggregation of local neoblasts. The migration of gastrodermal cells from the wound area causes the condensation of the parenchyma at the wound; the cytolyses of cells other than neoblasts in the parenchyma under a hypotonic condition evoke the aggregation of neoblasts. Active mitosis increases the number of neoblasts in the regeneration blastema. The “Parenchymal movement” or the mobility of the fixed parenchyma cells which must be responsible for the cellular transportation in the parenchyma was discussed.
The Effect of Light and Light Deprivation upon the Ultrastructure of the Larval Mosquito Eye. I. Polyribosomes and endoplasmic reticulum
Authors: White Richard H. , Sundeen Carol Deuel 
Published: June 2005

AbstractBy comparison with a photoreceptor cell that has been exposed to light for at least several hours, a cell from an animal grown in darkness is deficient in both rough and smooth endoplasmic reticulum. The free ribosomes of cells under either condition appear to be single or randomly clumped. Illumination of a previously light deprived cell stimulates the formation of free polyribosomes having a characteristic, probably helical, organizaation. They are found at first in association with the rough endoplasmic reticulum, and after 30 minutes, fill the cell. The polyribosomes are mostly gone after two hours of illumination. Illumination also stimulates an increase in the amount of endoplasmic reticulum, which reaches its maximum density by 12 hours of illumination. The discussion is concerned with the possible significance of these light induced ultrastructural changes to the protein metabolism of the photo‐receptor cell.
Field demonstration of polarotaxis in the fish Zenarchopterus
Authors: Waterman Talbot H. , Forward Richard B. 
Published: June 2005

AbstractOriented responses to linearly polarized light have been quantitatively confirmed in the marine teleost Zenarchopterus studied in underwater field experiments with the aid of SCUBA. During six successive mornings 2485 heading measurements were made on 36 untrained fish. With natural illumination spontaneous azimuth orientation is mutiply dependent on the sun's bearing and apparently on the natural polarized light of blue sky or water as well as the direction of the interisland channel where the fish were collected. When a dichroic filter is placed over the fish polarotaxis is manifest as directional preferences mainly perpendicular and less strongly, parallel to the plane of polarization. This response is most intense when the imposed e‐vector differs maximally (by 60°–90°) from that predominant in the natural illumination (90° to the sun's bearing). When the sun's disc is partly or wholly obscured by clouds polarotaxis is significantly weakened even though the polarization pattern visible to the fish through the dichroic filter would be virtually unchanged. More than moderate angular turning rates by the fish swimming in the experimental vessel also weaken their response to the e‐vector. Individual fishes show different reactions: about one‐third of those in full sunlight oriented strongly parallel and perpendicular to the imposed e‐vector, another smaller group appears to orient obliquely to the polarization plane while the remainder respond weakly to the e‐vector if at all. Continuing work is required to demonstrate the physiological mechanism and ecological significance of these behavioral patterns.
Gene transcription in mosaic embryos. I. The pattern of RNA synthesis in early development of the coot clam, Mulinia lateralis
Authors: Kidder Gerald M. 
Published: June 2005

AbstractOf the many investigations reported in the past decade concerning the pattern and significance of RNA synthesis in early development, relatively few have involved mosaic embryos. These investigations have revealed a common pattern of RNA synthesis among embryos of anamniotic deuterostomes and a few have indicated that this pattern may not be shared by their protostome counterparts. The present study provides data for a thorough comparison of RNA metabolism in a mosaic embryo with that of regulative embryos.Oocytes and embryos of the coot clam, Mulinia lateralis, were pulse‐labeled with tritiated uridine and their RNA was extracted and analyzed by sucrose gradient centrifugation and MAK chromatography. Little or no RNA synthesis could be detected in oocytes before fertilization. During cleavage, newly synthesized RNA is primarily DNA‐like, heterogeneous in size and base composition and of lower average G + C content than ribosomal RNA. A prominent class of short‐lived RNA molecules sedimenting at 8–10s is also transcribed during cleavage and continues to be produced at least through gastrulation. Transfer RNA appears to be synthesized as early as mid‐ to late‐cleavage. Whereas ribosomal RNA synthesis was undetectable in these experiments prior to gastrulation, ribosomal and transfer RNA synthesis predominate in the larval stages. These results demonstrate that the temporal pattern of RNA synthesis common to embryos of the lower deuterostome phyla can be found in protostome embryos as well, and therefore that mosaic development need not entail a unique pattern of gene transcription.
Endoderm movements in the chick embryo between the early short streak and head process stages
Authors: Rosenquist Glenn C. 
Published: June 2005

AbstractEndoderm movements in the chick embryo between the early short streak and head process stages were studied by tracing the migration of tritiated thymidine‐labeled grafts excised from explanted donor embryos and transplanted to identical positions in explanted recipient embryos of the same stage.During the primitive streak stages, the endoderm layer migrates in an orderly fashion away from a center of the primitive streak which is located about one fourth to one third of the distance from its anterior to its posterior end; all grafts placed in the endoderm anterior, lateral or posterior to this center migrated respectively anteriorly, laterally and posteriorly toward the outer margin of the area pellucida. During this migration, the grafts became narrowed and stretched out to conform with the rounded circumference of the area pellucida. Endoderm cells located in the endoderm center itself never completely left the streak, but spread out in all directions until they occupied a central circular area destined to form the gut.
Genetic and embryological studies of albinism in Rana pipiens
Authors: Browder Leon W. 
Published: June 2005

AbstractAlbinism in the leopard frog is due to a recessive gene (alb) in the homozygous condition. Heterozygous females produce normal, pigmented eggs. After fertilization of these eggs by sperm from another heterozygote, all progeny remain normally pigmented until after hatching when the albino progeny can be detected. Since melanin deposition in oocytes occurs prior to segregation of the alb and + alleles, the wild‐type gene may be transcribed and translated in the oocytes. Alternatively, the product of the + allele may be synthesized exogenously and incorporated into the oocytes during oogenesis.The results of embryonic transplant experiments suggest that the albino gene is expressed within the neural crest derivatives. Albino hosts support differentiation of wild‐type melanophores. Albino dorsal mesoderm induces melanophore differentiation in wild‐type neural crest derivatives.Albinos were less viable than their wild‐type siblings in the laboratory environment. Albino larvae developed scoliosis with high frequency, and albino frogs had a higher mortality rate after metamorphosis than their wild‐type siblings.
Polyspermy‐preventing mechanisms in the golden hamster egg
Authors: Barros C. , Yanagimachi R. 
Published: June 2005

AbstractThe zona pellucida of a fertilized egg recovered from an artificially inseminated female reacts to capacitated spermatozoa differently from the zona pellucida of an unfertilized egg. The zona of a fertilized egg shows a sperm‐refractory response, “zona reaction,” so that capacitated spermatozoa neither firmly attach to nor penetrates it. On the other hand, the zona of an unfertilized egg shows no such sperm‐refractory response and many spermatozoa attach to and penetrate it. The zona reaction was observed not only in recently penetrated eggs but also throughout cleavage.Judging from the earliest fertilization stage at which we observed a complete zona reaction, it is estimated that this reaction is completed in less than 15 minutes after sperm attachment to the vitellus.One hundred per cent of the fertilized eggs recovered from females five hours after artificial insemination were refertilized in vitro after removal of the zona pellucida by trypsin‐treatment. The incidence of refertilization decreased when the eggs were recovered at later times. Only 3% of the eggs recovered at nine hours after artificial insemination were refertilized. Judging from the fertilization stage at which eggs were no longer refertilizable, it has been estimated that the completion of the vitelline surface block to polyspermy is established in not less than two nor more than three to three and one‐half hours.Possible causes of polyspermy encountered with in vitro fertilized eggs are discussed.
Reversible re‐fusion of frog blastomeres and additional cleavage effects of chloramphenicol and other respiratory inhibitors
Authors: Lamy Loraine , Melton Charles G. 
Published: June 2005

AbstractChloramphenicol (CAP) produced an unusual cleavage anomaly in Rana pipiens embryos involving re‐fusion of normal looking 6 to 12 hour blastomeres into irregularly shaped syncytial mounds. This occurred whether the CAP was added then or earlier. The condition was usually terminal, but often at lower doses or following CAP removal the mounts re‐cleaved and the embryos resumed development. Preliminary histological verification of blastomere fusion has been obtained.The same anomaly was produced by two other inhibitors, rotenone and the L‐isomer of CAP. These are without effect on mitochondrial protein synthesis in other systems but do share with high doses of D‐CAP a direct inhibition of respiration at the NADH oxidase level. Another such inhibitor, amytal, failed to affect cleavage, presumably because of poor penetration. Instead, amytal produced uniform developmental arrest at later stages characteristic for each dose. Similar but less uniform results were obtained with lower doses of D‐ and L‐CAP, rotenone, cyanide, and dinitrophenol. All of these, however, also produced cleavage arrest at higher doses, including prevention of first cleavage altogether at high enough concentrations of each.This disagrees with the older literature in the case of cyanide, to which early cleavage is purported to be insensitive and the onset of gastrulation unusually sensitive. There is also an apparent conflict between our cyanide‐rotenonechloramphenicol results, suggesting that cleavage is dependent on respiration, and the work of others on cleavage under anaerobiosis, suggesting not. Several hypotheses which would resolve this conflict, including that of an oxidative reserve in the eggs, are presented and discussed.
Restriction of color in the rat with associated sterility in the male and heterochromia in both sexes
Authors: Gumbreck Laurence G. , Stanley Allan J. , Allison John E. , Easley Ronald B. 
Published: June 2005

AbstractThe effects of a new dominant gene in the rat are described. This gene, restricted (Hr e), causes a marked restriction of the colored areas of the body in the hooded, irish and self color patterns. Males with this restricted color pattern (Re) exhibit testicular tubular dysgenesis with consequent sterility, and a slightly reduced growth rate. The histological structure of the testis is described. Various experimental studies with the Re males are presented. These studies indicate that the cause of the sterility is a relative insensitivity of the germinal epithelium to pituitary follice‐stimulating hormone. There is a high incidence of heterochromia in Re rats with cream coat color and ruby eye.
On the mechanism of action in gonadotropic stimulation of oocyte maturation in Xenopus laevis
Authors: Merriam R. W. 
Published: June 2005

AbstractRipe ovarian follicles of Xenopus laevis, like those of Rana pipiens are capable of responding to gonadotropins even when their peritoneal epithelium and theca are removed by collagenase. Puromycin or cycloheximide stop oocyte maturation whether stimulated by gonadotropins or progesterone in vitro. Actinomycin D does not affect progesterone‐induced maturation but does show variable inhibition with gonadotropin‐induced maturation. Both gonadotropins and progesterone induce oocyte maturation to germinal vesicle breakdown in the same time. These data are taken as evidence that gonadotropins do not induce a macromolecular synthesis necessary for steroid release but rather simply induce the release of existing steroid in follicular epithelial cells.