45,X/46,X,idic(X)/47,X,idic(X),idic(X)嵌合体核型的研究

最常见的人类X染色体的结构异常是长臂等臂X染色体,以及X染色体与常染色体之间的易位。关于idic(X)染色体结构异常的病例较为罕见。国外Chapella等曾有研究,国内周氏等首次报道了有关idic(X)染色体结构异常的病例。     

45,X/46,XXr嵌合体

本文报告一例45,X/46,XXr嵌合体。患者徐××,表型女性,25岁,未婚。继发闭经,因阴蒂肥大而要求入院手术,维持女性。术中发现子宫为幼儿型,小而薄。右侧卵巢和输卵管缺如。左侧圆韧带薄而松弛。左侧输卵管长度正常但很细,卵巢小而薄。     

A phenotypic male with karyotype 45,X/45,X,ace+(?Yq-)

Summary A phenotypical normal 22-year-old male with the sex chromosome constitution 45,X/45,X,ace+(?Yq-) and an atypical endogenous depression has been studied. The chromosome aberration and the depression are most probably not aetiologically connected.The patient presented no physical signs of male Turner phenotype, except for short stature. His personality development was, however, in several ways similar to what is characteristic for females with Turner's syndrome and karyotype 45,X and he had some dermatoglyphic signs similar to females with Turner's syndrome.The cytogenetic findings in leucocytes as well as fibroblast cultures indicated that the small acentric chromosome fragment found in approximately half of the cells was made up of the short arms of a Y chromosome. The finding of only short arms Y chromosome in approximately half of the cells in a phenotypically normal male with testes of normal size supports indications from previous studies that the genes necessary for the development of testes are located in the short arms Y. The finding further indicates that if homologous gene loci for the short arms X are present in the Y chromosome, they must be located in the short arms, and deletion long arms Y is most probably not an aetiological factor in the development of the so-called male Turner phenotype.

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Zusammenfassung Es wird ein phänotypisch normaler 22jähriger Mann mit der Geschlechtschromosomenkonstitution 45,X/45,X,ace+(?Yq-) und einer atypischen endogenen Depression beschrieben. Die Chromosomenaberration und die Depression stehen sehr wahrscheinlich in keinem ätiologischen Zusammenhang.Der Patient zeigte keine körperlichen Veränderungen im Sinne der männlichen Turner-Phänotype, mit Ausnahme von Kleinwuchs. Seine Persönlichkeitsentwicklung jedoch ließ sich in mehreren Punkten mit den Charakteristika, wie man sie bei Frauen mit Turner-Syndrom und der Karyotype 45,X sieht, vergleichen; und er hatte einige dermatoglyphische Zeichen, ähnlich wie bei Frauen mit Turner-Syndrom.Die cytogenetischen Untersuchungsergebnisse sowohl an Leukocyten als auch an Fibroblastenkulturen deuteten an, daß das kleine azentrische Chromosomenfragment, welches sich in ungefähr der Hälfte der Zellen fand, von den kurzen Armen des Y-Chromosoms gebildet wurde. Der Fund von lediglich den kurzen Armen des Y-Chromosoms in ungefähr der Hälfte der Zellen bei einem phänotypisch normalen Mann mit normaler Testisgröße unterstützt die Vermutungen vorangegangener Untersuchungen, daß die Gene, die für die Entwicklung der Testis notwendig sind, auf den kurzen Armen des Y-Chromosoms lokalisiert sind. Das Ergebnis der Untersuchung deutet weiterhin an, wenn homologe Genloci für die kurzen Arme X im Y-Chromosom vorhanden sind, diese auf den kurzen Armen lokalisiert sein müssen und daß eine Deletion der langen Arme des Y-Chromosoms sehr wahrscheinlich kein ätiologischer Faktor in der Entwicklung der sogenannten männlichen Turner-Phänotype ist.

     

A girl with mosaicism for a dicentric X chromosome (45,X/46,X,dic(X) (Xqter→p22::p22→qter))

Summary A 12-year-old girl was examined for growth retardation and a few very discrete dysmorphologic stigmata of Turner's syndrome; the genitalia were infantile yet both ovaries possessed functioning follicles. R- and C-banding techniques and Brdu treatment demonstrated a 45,X formula in 95% of lymphocytes, with 5% presenting a 46,X,dic(X) formula. Cytogenetic and clinical problems raised by this observation are discussed in relation to data from the literature.This work was supported by grants from the Institut National de la Santé et de la Recherche Médicale (C.R.L. 75-10-42-24) and from the C.R.E.M.A.G.     

45,X及46,XX男性的起因——X—Y交换机制的探讨

自1957年弗格森-史密斯(Ferguson-Smith)对男性不育进行研究,已发现某些染色体异常可导致不育症,其中XX或X男性是男性不育原因之一。本文收集的68例X及XX男性,其中46,XX男性37例,约占54%,45,X男性8例,占11%,两性畸形17例,约占25%,1例46,XX/47,XXX男性嵌合体,5例Y染色体不同程度的缺失和1例Y染色体长臂与15号染色体短臂易位表现为女性。其中丹麦哥本哈根实验室从1973-1980年对5.580例孕妇进行羊膜穿     

X,Y精子分离技术的进展

自本世纪伊始,就有许多有关分离X精子(具有X染色体的精子)和Y精子(具有Y染色体的精子)的研究报告.近年来,美国、日本等国相继报道分离人和牛的X、Y精子获得成功,然而其实验效果的重复性极低.本文仅就最近有关X、Y精子的分离研究进展情况作以扼要的介绍.     

Structures and aromaticity of X2Y 2 − (X = C, Si, Ge and Y = N, P, As) anions

The equilibrium geometries, total energies, and vibrational frequencies of anions X₂Y₂ ⁻ (X = C, Si, Ge and Y = N, P, As) are theoretically investigated with density functional theory (DFT) method. Our calculation shows that for C₂N₂ ⁻ species, the D _2h isomer is the most stable four-membered structure, and for other species the C _2v isomer in which two X atoms are contrapuntal is the most stable structure at the B3LYP/6-311 +G_* level. Wiberg bond index (WBI) and negative nucleus-independent chemical shift (NICS) value indicate the existence of delocalization in stable X₂Y₂ ⁻ structures. A detailed molecular orbital (MO) analysis further reveals that stable isomers of these species have strongly aromatic character, which strengthens the structural stability and makes them closely connected with the concept of aromaticity.     

Theoretical study on cooperative effects between X⋯N and X⋯Carbene halogen bonds (X = F,Cl,Br and I)

Quantum chemical calculations are performed to study the interplay between halogen?nitrogen and halogen?carbene interactions in NCX?NCX?CH₂ complexes, where X?=?F, Cl, Br and I. Molecular geometries and interaction energies of dyads and triads are investigated at the MP2/aug-cc-pVTZ level of theory. It is found that the X?N and X?C_carbene interaction energies in the triads are larger than those in the dyads, indicating that both the halogen bonding interactions are enhanced. The estimated values of cooperative energy E _coop are all negative with much larger E _coop in absolute value for the systems including iodine. The nature of halogen bond interactions of the complexes is analyzed using parameters derived from the quantum theory atoms in molecules methodology and energy decomposition analysis.

Biosynthesis,isolation, purification and separation of nivalenol,fusarenone — X and zearalenone

Fusarium, graminearum KF 370 isolate is able to simultaneous biosynthesis of three toxic metabolites, namely: fusarenone-X (FUS), nivalenol (NIV) and zearalenone (F-2). After metabolites extraction with methanol — water (3:1) and defatting with n-heptane toxins were partitioned into chloroform layer. Purification of the? compounds was performed on Celite 545 — charcoal — Aluminiumoxid 90 column then metabolites were separated on Kieselgel 60 (200–300 mesh) column with developing solvent chloroform — methanol. This way FUS, NIV and F-2 were obtained as crystalline or high purity standards.     

一例原发闭经46,X,psu dic(X)(p22. 3::p22.3)

国外自1974年来,已有等臂双着丝粒X的多种病例报道^[5,6]。我国1982年才开始报道,至今已报道约有6例^[1-3]。现将我室发现一例报告如下。     

谷子与轮生狗尾草（2X,4X）种间的亲缘关系分析

将同工酶技术与细胞遗传学相结合,对谷子与轮生狗尾草（２Ｘ、４Ｘ）野生种之间的遗传与进化关系进行了分析。分析结果表明：谷子与轮生狗尾草四倍体类型（４Ｘ）具有一定的同源性,而与轮生狗尾草二倍体类型（２Ｘ）的同源性较少。轮生狗尾草四倍体类型与轮生狗尾草二倍体类型具有与谷子相近的同淅性。青狗尾草（谷子）和轮生狗尾草二倍体类型（２Ｘ）是轮生狗尾草四倍体类型（４Ｘ）最可能的两个祖先种。轮生狗尾草二倍体类型与四     

一例46, X,i(Xp）引起的过早绝经

我们从妇科门诊检查1例曾有过月经史、 妊娠史的继发性闭经患者，经细胞遗传学研究， 首次检出46, Xi(Xp)o 46, X, i(Xp）是Turners 综合征中的一种表现形式，所查阅的国内外文 献尚未见到类似报道。现报告如下。     

Center for barr body condensation. A case of Turner's syndrome with 45,X/46,X,dic(X) (Xqter→ p22::p22→qter)

Summary An 11-year-old girl with karyotype 45,X/46,X,dic(X) (Xqterp22::p22qter) is presented. The abnormal X is always found to be the inactive and late replicating X, and according to previous investigations by Therman et al. (1974) part of the cells are seen to have bipartite Barr bodies.     

一例罕见的X—常染色体平衡易位[46,X,t(Xq~+;15q~-)]伴发自然流产

有关夫妇一方为平衡易位携带者所致流产、死胎及先天性多发畸形的情况,近年来多见报道,并日益引起妇产科医师和医学遗传工作者的重视。绝大多数平衡易位发生在常染色体与常染色体之间,极少发生在X染色体与常染     

An internal ligand-bound,metastable state of a leukocyte integrin, αXβ2

How is massive conformational change in integrins achieved on a rapid timescale? We report crystal structures of a metastable, putative transition state of integrin α_Xβ₂. The α_Xβ₂ ectodomain is bent; however, a lattice contact stabilizes its ligand-binding αI domain in a high affinity, open conformation. Much of the αI α7 helix unwinds, loses contact with the αI domain, and reshapes to form an internal ligand that binds to the interface between the β propeller and βI domains. Lift-off of the αI domain above this platform enables a range of extensional and rotational motions without precedent in allosteric machines. Movements of secondary structure elements in the β₂ βI domain occur in an order different than in β₃ integrins, showing that integrin β subunits can be specialized to assume different intermediate states between closed and open. Mutations demonstrate that the structure trapped here is metastable and can enable rapid equilibration between bent and extended-open integrin conformations and up-regulation of leukocyte adhesiveness.     

Theoretical study of [ XN5 ]− (X=O, S, Se, Te) systems

A series of [XN₅]⁻ (X=O, S, Se, Te) compounds has been examined with ab initio and Density Functional Theory (DFT) methods. The five-membered nitrogen ring series of structures are global minima and may exist or be characterized due to their significant dissociation barriers (29.7–32.7 kcal mol⁻¹). Nucleus-independent chemical shifts (NICS) criteria and the presence of (4n+2) π-electrons confirmed that the five-membered nitrogen ring in their structures exhibits characteristics of aromaticity. Thus, the strong stability of the five-membered nitrogen ring structures may be attributed partially to their aromaticity.      

Two X family DNA polymerases, λ and μ, in meiotic tissues of the basidiomycete, Coprinus cinereus

The X family DNA polymerases λ (CcPolλ) and μ (CcPolμ) were shown to be expressed during meiotic prophase in the basidiomycete, Coprinus cinereus. These two polymerases are the only members of the X family in the C. cinereus genome. The open reading frame of CcPolλ encoded a predicted product of 800 amino acid residues and that of CcPolμ of 621 amino acid residues. Both CcPolλ and CcPolμ required Mn²⁺ ions for activity, and both were strongly inhibited by dideoxythymidine triphosphate. Unlike their mammalian counterparts, CcPolλ and CcPolμ had no terminal deoxynucleotidyl transferase activity. Immunostaining analysis revealed that CcPolλ was present at meiotic prophase nuclei in zygotene and pachytene cells, which is the period when homologous chromosomes pair and recombine. CcPolμ was present in a slightly wider range of cell stages, zygotene to diplotene. In analyses using D-loop recombination intermediate substrates, we found that both CcPolλ and CcPolμ could promote primer extension of an invading strand in a D-loop structure. Moreover, both polymerases could fully extend the primer in the D-loop substrate, suggesting that D-loop extension is an activity intrinsic to CcPolλ and CcPolμ. Based on these data, we discuss the possible roles of these polymerases in meiosis.     

Genome-wide profiling of liver X receptor, retinoid X receptor, and peroxisome proliferator-activated receptor α in mouse liver reveals extensive sharing of binding sites

The liver X receptors (LXRs) are nuclear receptors that form permissive heterodimers with retinoid X receptor (RXR) and are important regulators of lipid metabolism in the liver. We have recently shown that RXR agonist-induced hypertriglyceridemia and hepatic steatosis in mice are dependent on LXRs and correlate with an LXR-dependent hepatic induction of lipogenic genes. To further investigate the roles of RXR and LXR in the regulation of hepatic gene expression, we have mapped the ligand-regulated genome-wide binding of these factors in mouse liver. We find that the RXR agonist bexarotene primarily increases the genomic binding of RXR, whereas the LXR agonist T0901317 greatly increases both LXR and RXR binding. Functional annotation of putative direct LXR target genes revealed a significant association with classical LXR-regulated pathways as well as peroxisome proliferator-activated receptor (PPAR) signaling pathways, and subsequent chromatin immunoprecipitation-sequencing (ChIP-seq) mapping of PPARα binding demonstrated binding of PPARα to 71 to 88% of the identified LXR-RXR binding sites. The combination of sequence analysis of shared binding regions and sequential ChIP on selected sites indicate that LXR-RXR and PPARα-RXR bind to degenerate response elements in a mutually exclusive manner. Together, our findings suggest extensive and unexpected cross talk between hepatic LXR and PPARα at the level of binding to shared genomic sites.     

45,X/46,XY qh? Karyotype and Aspermia. A case report

A 41-years old male with short stature, abnormal male sex differentiation, aspermia and schizoid character disorder is described. The patient was studied from clinical, endocrinological and genetic perspectives. Cytogenetical analysis revealed a chromosomic mosaicism formed by two normal lines 45X and 46,XY qh^?. Molecular studies on AZF region evidenced that it was conserved. The correlation of the symptoms with the cytogenetic finding is discussed.     

A point mutation,R59G,within the HMG-SRY box in a female 45,X/46,X,psu dic(Y)(pter→q11::q11→pter)

We report a molecular and cytogenetic investigation of a psu dic(Yp) chromosome identified in blood and ovarian tissue from a female with mosaic karyotype 45,X/46,X,+ psu dic(Yp). FISH analysis showed that the psu dic(Yp) has two copies of the short arm, two centromeres and two copies of the proximal long arm. PCR analysis also confirmed the presence of the SRY gene and the Y centromere, and also confirmed the deletion of the Y-heterochromatic region. Because of the possibility of a mutation, a fragment of 609 bp of the SRY gene was sequenced from independent PCR products. The analysis of the sequence indicated the presence of two different copies of the gene: one presented a point mutation, R59G, within the HMG-box; the other had a sequence identical to that already published. Both sequences were found at a proportion of 1:1. The absence of a 46,XY cell line suggests that the rearrangement took place during gametogenesis or during the first division after fertilization. Also, the existence of different sequences of the SRYgene in the same Y chromosome suggests that the formation of the dicentric took place prior to the mutation of the SRY gene. To our knowledge, this is the first time that a mutation has been described in codon 59 within the HMG- SRY box, and also the first case of a psu dic(Yp) chromosome that displays two different copies of the SRY gene.