指纹遗传的双生子研究——Ⅱ.指纹纹型的研究

采用双生子法对26对MZ及24对DZ的指纹纹型进行研究,发现在各类指纹纹型中,斗形最多,桡箕最少。男女间纹型频率差异不大。纹型的左右手对称性为77.20％。作者提出了指纹系数的计算公式,即[(斗形纹数)+(斗形纹数+箕形纹数)]×100％。认为以此来反映10指纹型的构成和复杂程度,以及分析指纹较为合适。 纹型和三辐线在MZ与DZ对间一致率的比较,以及指纹系数、花样强度和生物学指纹价在MZ与DZ对间的相关系数的比较,发现MZ对间的一致率及相关系数明显高于DZ对间的一致率及相关系数,其遗传度为56—92％。本文发现指纹系数在MZ对间并非完全一致,即MZ对间纹型不一致,且指纹系数呈一连续常态分布。纹型的分析表明,指纹纹型以多基因遗传的可能性较大,但不能排除异质性遗传的可能。     

The twisted umbilical cord: An expression of kinesis of the equine fetus?

The umbilical cord of 157 equine conceptuses of various ages were examined for the presence, frequency, location, degree and direction of umbilical twists. The intra-uterine disposition of 57 conceptuses was also controlled. 78% of the cords were twisted and they attained an average of 4.4 twists per umbilical cord. By inclusion of the cords without torsion a general average of 3.5 twists per examined umbilical cord was obtained. This average was already reached at four months gestation and remained unchanged until at term. Twisting had no preferential direction and was not influenced by twin-gestation compared to single pregnancies. Twisting in the amniotic and in the allantoic part occurred independently.In pregnancies of 4 to 7 months, approximately 50% of the fetuses were found in anterior presentation. At about 7 months, the fetus had developed a final rotation resulting in 97% of fetuses in the anterior presentation.Twisting of the equine umbilical cord can be accepted as a generalized physiological phenomenon. A comparison of the theoretical possibilities of the twisting mechanism with the data of the present study, and with developmental and clinical facts indicates that the fetal movements themselves perform the principal role in the twisting process.     

The influence of genetic and environmental factors on the etiology of the human umbilical cord: the East Flanders prospective twin survey

The umbilical cord is vulnerable to a number of insults that may alter cord morphology, diminish cord flow, and ultimately compromise fetal nutrition. Thus, an investigation of the underlying mechanisms of the development of cord morphology and possible pathologies associated with it may provide insight regarding fetal growth in the intrauterine environment and have an impact on later development of the child. To our knowledge, this study, which included 11,980 twins, is the first to report the relative contribution of genes and environment in the development of the cord. Umbilical cord length, insertion, knots, twisting, and number of vessels were examined by trained midwives at birth. Means and percentages of cord characteristics by twin zygosity/chorionicity and gender were calculated. ANOVA and chi-square tests were performed to calculate discordance in cord morphology between dizygotic (DZ), monozygotic monochorionic (MZMC), and monozygotic dichorionic (MZDC) twins. Univariate genetic models were fit to the umbilical cord characteristics to investigate the genetic and environmental influences on umbilical cord morphology. Mainly nonshared environmental but also genetic factors influence umbilical cord morphology. In MZMC male and female twins, a peripheral/marginal cord insertion was significantly (P < 0.01) more prevalent compared to MZDC and DZ male and female twins, respectively. In MZMC male twins, clockwise twisting was significantly (P = 0.02) less frequent compared to DZ twins. Environmental and genetic factors influence cord morphology and pathology. Twin members can experience environmental influences that are not shared between them even in that very early stage of in utero life.     

Metacarpo-phalangeal and ring creases in twins

Metacarpo-phalangeal creases including the ring crease were studied on the middle finger of Japanese twins. The mean of differences and the correlation coefficient of the ring crease index as well as fine morphological features showed that the similarity between twins is greater in monozygotic twins than in dizygotic ones. The intrapair similarity in monozygotic twins is almost the same as that between right and left hands of an individual. For the diagnosis of zygosity this trait will be available.     

Alpha helical crossovers favor right‐handed supersecondary structures by kinetic trapping: The phone cord effect in protein folding

The remarkable predominance of right‐handedness in beta‐alpha‐beta helical crossovers has been previously explained in terms of thermodynamic stability and kinetic accessibility, but a different kinetic trapping mechanism may also play a role. If the beta‐sheet contacts are made before the crossover helix is fully formed, and if the backbone angles of the folding helix follows the energetic pathway of least resistance, then the helix would impart a torque on the ends of the two strands. Such a torque would tear apart a left‐handed conformation but hold together a right‐handed one. Right‐handed helical crossovers predominate even in all‐alpha proteins, where previous explanations based on the preferred twist of the beta sheet do not apply. Using simple molecular simulations, we can reproduce the right‐handed preference in beta‐alpha‐beta units, without imposing specific beta‐strand geometry. The new kinetic trapping mechanism is dubbed the “phone cord effect” because it is reminiscent of the way a helical phone cord forms superhelices to relieve torsional stress. Kinetic trapping explains the presence of a right‐handed superhelical preference in alpha helical crossovers and provides a possible folding mechanism for knotted proteins.     

Retrospective determination of chorion type in twins using a simple questionnaire.

This study investigates the validity of retrospective determination of chorion type by asking the question to the mother about the number of placentas. In the "East Flanders Prospective Twin Survey" (EFPTS), accurate information on the placentation and zygosity of the multiples was collected prospectively. The mothers of 231 monozygotic (95 dichorionic and 136 monochorionic) twins and 255 dizygotic twins were asked to fill in a simple questionnaire regarding 1). the zygosity and 2). the number of placentas of their twins. The accuracy of the response to the question on "the number of placentas" was 60% for monozygotic twins and 37% for dizygotic twins. The accuracy of the response to the question on the zygosity of the twins was 93% for monozygotic and 95% for dizygotic twins. If the questionnaire was used for the determination of chorion type, a total of 31 monozygotic twins (13%) should have been assigned as dichorionic on the fact that there were two separate placentas. Of these, 10 (32%) are monochorionic and 12 (39%) were falsely reported as having two placentas. We conclude from these findings that this simple questionnaire method is unreliable for the retrospective determination of the chorion type.     

Lethality and "petite" mutation induced by the photoaddition of 8-methoxypsoralen in yeast: influence of ploidy, growth phases and stages in the cell cycle.

Summary The wild type nematode,Caenorhabditis elegans, moves in a sinusoidal wave pattern and leaves sinusoidal paths behind it on a bacterial lawn. The nematode crawls on its side on a special cuticular tread that extends straight down the length of its body. Wild type worms also have rows of musculature and a ventral nerve cord that extend straight down the body. Roller mutants rotate around their long axis as they crawl and move in circular paths. Three roller mutants have been studied. Two mutants are left rollers and one is a right roller. The left rollers have left-handed helical treads, body musculatures, and ventral nerve cords whereas these structures are right-handed helices in the right roller. Double mutants constructed from roller mutants and long mutants indicate that long rollers have helices of the same pitch as normal length rollers. Double mutants constructed from rollers and dumpy mutants that are short and fat indicate dumpy phenotype is epistatic to roller. Double mutants constructed from rollers and blister mutants that have cuticular swelling indicate roller phenotype is epistatic to blister. The results suggest that the roller phenotypes are due to cuticular lesions. Rollers can chemotaxe up a gradient of an attractant by turning off their body muscle movement and continuing their head movements.     

Lumbar lateral motor columns and hindlimbs of two Xenopus laevis chromosome mosaics

Two chromosome mosaic Xenopus laevis, one tadpole and one metamorphic animal, both with different sizes of neurons on the left and right sides of their brains and spinal cords, have left and right lumbar lateral motor columns (L-LMCs) of equal lengths but composed of strikingly different numbers of motoneurons (40% fewer motoneurons on the side composed of larger cells). One portion of the lumbar cord in the metamorphic animal is bilaterally symmetrical; the cells on both sides are small and the numbers of motoneurons per section are the same. The mosaics demonstrate that column length and motoneuron density (number per section) are, or can be, regulated bilaterally and that changing cell size affects factors controlling cell density but not column length. Except for the peripheral nerves, there is no evidence of any side-to-side differences in the hindlimb tissues. Whether the side-to-side difference in L-LMC motoneuron number in the stage 66 mosaic corresponds to any feature of the hindlimbs is unknown, but similar side-to-side differences in an early and a late stage mosaic animal support the idea that whatever creates the initial number may also determine the final number of motoneurons.     

Twisted growth and organization of cortical microtubules

In plants, directional cell expansion greatly contributes to the final shape of mature cells, and thus to organ architecture. A particularly interesting mode of cell expansion is helical growth in which the growth axis is continuously tilted either to the right or to the left as the cell grows. Fixed handedness of helical growth raises fundamental questions on the possible origin of left–right asymmetry. Twisting mutants of Arabidopsis thaliana offer unique opportunities to study the cellular basis of helical growth. Most of the twisting mutants with fixed handedness have been shown to have defects in microtubule functions, whereas mutants that twist in non-fixed directions appear to be defective in auxin response or transport. Good correlations have been found between the tilted growth direction and alignment of cortical microtubule arrays in twisting mutants with compromised microtubule functions. The present challenge is to understand how particular array patterns are organized during progression of the interphase in rapidly expanding cells. Molecular and cell biological studies on twisting mutants will lead to better understanding on how wild-type plant cells utilize the microtubule cytoskeleton to initiate and rigorously maintain straight growth. An erratum to this article can be found at     

X-ray anatomic features of the skeletons of twin children

The size of right and left middle phalanges in the II-V fingers and the III finger have been studied in 108 pairs of monozygotic and dizygotic twins at 8--19 years of age and in 60 paris (pedagogical experiment) of separated twins (from the same pair), schoolchildren of the 2d--5th forms trained according different programs of physical culture. A great similarity of osteometric signs has been stated in monozygotic twins. As to local (intradigital) differences, a prevalence of the IIId finger should be mentioned. Maximum of genetic determination is evident for transversal growth--under high mechanical loadings on the bones, for longitudinal--under low mechanical loadings. The data of the pedagogical experiment demonstrate that increased mechanical loading on the hand bones activates osteogenesis. According to the majority of indices the main is the "radial" (II--III fingers) type.     

Effect of genotype on evoked potentials of the left and right hemispheres during perception of visual stimuli

Intrapair similarity of evoked potentials (EPs) to light flash, checkerboard, house picture, the word "house" and a number of other stimuli was estimated in 20 pairs of monozygotic and 20 pairs of dizygotic adult twins of the same gender. In the right temporal area the level of the genotypic control of amplitude-temporal parameters of EPs on the whole is higher than in the left one; the more prominent this difference is in responses to spatial-structural stimuli. In the left temporal area, the genotypic control is manifested in latencies of components of EPs to linguistic stimuli.     

Hand clasping--an overview]

The literature concerning the asymmetry clasping hands is reviewed based on 192 studies. This paper describes the incidence, sex differences, age differences and genetical problems including twinning. The incidence of left hand clasping ranges from 30% to 75% (mean 43%). The review confirms the so-called east-west-gradient and there is a predominance of the left type in Europe. Age and sex differences are only small. There is only a small relationship between hand clasping and handedness. 18 authors examined hand clasping in families and 4 in twins. The family data suggest that hand clasping may be under genetic control, yet it is clear that no simple genetic model for the inheritance can be applied. Both monozygotic and dizygotic twins show a low concordance and the R-R, R-L and L-L pairs in monozygotic and dizygotic twins are in binomial distribution.     

Activity of nucleolus organizer regions (NORs) in embryonic livers from twin minks]

Ag-NOR patterns were studied in hepatocytes from nine mink embryo siblings, including a pair of monochorionic (presumably monozygotic, MZ) twins. Both the number and the size of Ag-NORs per cell were found to be identical in MZ twins. All the other sibs had the patterns different from each other and from the MZ ones. The conclusion is that the NORs activity is a strongly inherited character and the Ag-NOR pattern can be used as a reliable genetic marker to distinguish the twin zygosity.     

Genetic studies on nucleolus organizer regions (NORs) in cattle

Experimentally produced monozygotic twins, natural opposite sex blood chimeras (freemartins), and several pedigrees were used to evaluate the genetic influences on the nucleolus organizer region (NOR) patterns in cattle. In monozygotic twins, the NOR patterns of both twins are extremely similar. In chimeras, NOR patterns of genetically identical, peripheral blood lymphocytes (PBL) from the two partners resemble each other. In contrast, genetically different PBL (sib organ) differ significantly in the same environment. A high heritability of the individual NOR patterns is also demonstrated in our 23 pedigrees. In conclusion, our data demonstrate that variation in NOR expression is predominantly due to genetic factors.     

Propeller Twisting in Single Crystals of Nucleosides

Abstract

Propeller twists were measured for base-paired nucleosides and nucleic acid bases. The occurrence of propeller twist outside a double helical framework is shown, and conclusions drawn on the relative magnitude of the effect in single nucleosides.     

Zygosity misclassification of twins at birth in Japan.

Though twinning rates have been rapidly increasing in Japan, the problem of zygosity misclassification at birth has been paid little attention. By analyzing four independent samples, the authors found that at a constant rate about 25-30% of monozygotic twins were misclassified as dizygotic twins at birth. This percentage is in very good accordance with that of monozygotic twins having dizygous placenta. Generally the obstetricians informed twins' parents about their children's zygosity. The number of placentas, as informed by obstetricians, was very strongly associated with zygosity. Concluding, even now many monozygotic twins in Japan may be misclassified as dizygotic at birth by obstetricians based solely on the number of placenta.     

Characterization of nutrition-induced helix hand inversion of Bacillus subtilis macrofibers.

The kinetics of Bacillus subtilis macrofiber helix hand inversion was examined. Inversion was induced by transfer of structures produced in one medium to another medium. When cultured at 20 degrees C in either medium, the doubling time was approximately 100 min. To establish a baseline, the macrofiber twist state produced in one medium was measured over the same time course during which other macrofibers underwent inversion after transfer to a second medium. The baseline was used to identify the time of inversion initiation: the point at which curves representing changes of twist as a function of time after transfer to the new medium intersected the baseline. Right- and left-handed macrofibers of different twists were produced by growth in mixtures of TB and S1 media. These were used to determine the influence of initial twist on the time course of inversion initiation. In the right to left inversion, a positive correlation was found between initial twist and the time of inversion initiation. The left to right inversion differed, however, in that a constant time was required for inversion initiation regardless of the starting left-handed twist. When a nutritional pulse was administered by transferring fibers from TB to S1 to TB medium, the time to initiation of inversion was found to decrease with incubation of increasing duration in S1 medium. A similar pulse protocol was used in conjunction with inhibitors to examine the protein and peptidoglycan synthesis requirements for the establishment of nutrition-induced memory that leads to initiation of inversion. Nutritionally induced right to left inversion but not left to right inversion required protein synthesis. The addition of trypsin to left-handed macrofibers apparently required, as described previously for the temperature-regulated twist system (D. Favre, D. Karamata, and N. H. Mendelson, J. Bacteriol. 164:1141-1145, 1985), for the production of left-handed twist states in the nutrition system.