胰岛素对βTC-3 细胞胰岛素受体表达的作用

目的:观察外源性胰岛素对小鼠胰岛β细胞瘤细胞株βTC-3细胞胰岛素受体表达的影响。方法:采用免疫荧光细胞化学技术结合激光扫描共聚焦显微镜观察高浓度胰岛素(100 IU/ml)刺激不同时间(0 min、30 min、60 min、120 min、240 min),培养的βTC-3细胞胰岛素受体的表达,用Image pro plus软件对胰岛素受体的荧光强度进行了半定量分析。结果:与0 min比较,胰岛素孵育30 min、60 min、120 min、240 min时胰岛素受体荧光强度均明显下降(P<0.05)。结论:高浓度胰岛素孵育βTC3细胞后,可明显下调胰岛素受体的表达,这可能是高胰岛素血症导致胰岛素抵抗产生的机制之一。     

Nonreplication of heterochromatic chromosomes in a mealy bug,Planococcus citri (Coccoidea: Homoptera)

In males of mealy bugs with the lecanoid chromosome system, the paternal set of chromosomes becomes heterochromatic in early embryogeny. In males of the mealy bug, Planococcus citri, the heterochromatic (H) set in testis sheath cells and in most of the oenocytes apparently did not replicate while the euchromatic (E) set was undergoing several cycles of endoreplication. In third instar males, testis sheath cells in endoanaphase and endotelophase exhibited 5H and either 40 or 80E chromosomes. The increase in the number of E chromosomes was attributed to the replication of only the E chromosomes. Oenocytes of third instar males had 0, 5, or 10H chromosomes and from 10 to 240E chromosomes. The oenocytes with 5H chromosomes had a mean of 50.8E chromosomes, and those with 10H chromosomes had a mean of 155.6E chromosomes. Nuclear and cell fusion was considered as a means of producing the various numbers of H and E chromosomes in oenocytes, and it was concluded that although nuclear fusion probably took place, the differences between the number of H and E chromosomes was at least in part due to replication of only the E chromosomes. The size of the H chromosomes was about the same in all the testis sheath cells and the oenocytes irrespective of the level of endopolyploidy for the E set. These H chromosomes apparently did not increase in polyteny, because they were only about half the size of the H chromosomes in prophase I of spermatogenesis. The significance of the nonreplication of the H set and the control of nonreplication are briefly discussed.This study was aided by a grant (GB-1585) from the National Science Foundation, Washington, D.C.     

胰岛素对βTC-3细胞胰岛素受体表达的作用

目的：观察外源性胰岛素对小鼠胰岛β细胞瘤细胞株βTC-3细胞胰岛素受体表达的影响。方法：采用免疫荧光细胞化学技术结合激光扫描共聚焦显微镜观察高浓度胰岛素（100 IU/ml）刺激不同时间（0 min、30 min、60 min、120 min、240 min）,培养的βTC-3细胞胰岛素受体的表达,用Image pro plus软件对胰岛素受体的荧光强度进行了半定量分析。结果：与0 min比较,胰岛素孵育30 min、60 min、120 min、240 min时胰岛素受体荧光强度均明显下降（P〈0.05）。结论：高浓度胰岛素孵育βTC3细胞后,可明显下调胰岛素受体的表达,这可能是高胰岛素血症导致胰岛素抵抗产生的机制之一。     

Occurrence of differential meiotic associations and additional chromosomes in the embryo-sac mother cells of Allium roylei Stearn

A small population of complex translocation heterozygote plants of Allium roylei from the Bani region of Jammu Province was studied for meiosis in the female track. This study resulted in identification of two variants, having embryo-sac mother cells (EMCs) with more than 16 chromosomes. EMCs of the remaining plants invariably had diploid (2n = 16) chromosome complement. Female meiosis, in general, was found to be abnormal, with nearly 23% and 11% chromosomes associating as quadrivalents or trivalents at prophase I and at metaphase I, respectively. This was followed by irregular segregation of chromosomes at anaphase I. Amongst the variants; one had 38% EMCs with eight bivalents plus two small sized chromosomes. Their small size, dispensable nature and tendency to affect the pairing behaviour of normal complement are some of the features that latter chromosomes share with the B chromosomes. Seventeen to nineteen chromosomes were observed in 35% EMCs of other variant; the remaining cells had 16 chromosomes. Chromosomal behaviour in both kind of cells (euploid and aneuploid) was more or less similar. Unlike female meiocytes, male meiocytes analysed earlier of this strain always had 16 chromosomes which paired to form extremely complex associations involving 3-16 chromosomes. The most likely cause of this asynchrony with regards to number of chromosomes involved in multivalent formation seems to be interaction of genes controlling chiasma formation with the different physiological conditions of male and female meiocytes.     

A new chromosome type replacing the double minutes in a mouse tumor.

For several years the SEWA mouse ascites tumor has been a carrier of double minute chromosomes (DMs), some 90% of its cells containing from one to several hundred DMs. In one specific subline of this tumor, the cells with DMs had decreased in frequency to less than 5% of the cells. At the same time, the stemline chromosome number had increased from 43 to around 50. This was due to the presence, in addition to the ordinary telocentric chromosomes, of a varying number of medium-sized metacentrics. The fact that these chromosomes deviated from ordinary mouse chromosomes in special features, such as median centromeric position, early DNA replication, and complete lack of centromeric heterochromatin, indicates that they represent a new type of chromosome. Their striking agreement with the DMs in many properties makes it tempting to associate their origin with the disappearance of the DMs.     

Quantitative studies on the arrangement of human metaphase chromosomes

Summary The association pattern was studied in 2715 mitoses of 90 meningiomas with different numbers of acrocentric chromosomes. In cells with monosomy 22, a significant increase of mitoses with associations was observed in comparison to cells with a normal karyotype. The number of associating acrocentric chromosomes was highly significantly increased. This surplus was not only caused by a highly significant increase of associating G chromosomes but also of D chromosomes. The loss of further acrocentric chromosomes had no significant influence on the number of mitoses with associations or the number of associating chromosomes. Based on the well-known correlations between the nucleolus organization and the association pattern, the results seem to indicate a compensation mechanism among the nucleoles organizing regions (NOR's) which keeps the supply of nucleolar material constant and simultaneously causes a higher association tendency between the remaining acrocentric chromosomes. The increase of associations in the 22 monosomic cells was interpreted as a overcompensation after the loss of only one NOR.     

Positioning of the NOR-bearing chromosomes in relation to nucleoli in daughter cells after mitosis

It is known that chromosomes occupy non-random positions in the cell nucleus. However, it is not clear to what extent their nuclear positions, together with their neighborhood, are conserved in daughter cells. To address specific aspects of this problem, we used the model of the chromosomes carrying ribosomal genes that are organized in clusters termed Nucleolus Organizer Regions (NORs). We compared the association of chosen NOR-bearing chromosomes (NOR-chromosomes) with nucleoli, as well as the numbers of nucleoli, in the pairs of daughter cells, and established how frequently the daughter cells had equal numbers of the homologs of certain NOR-chromosomes associated with individual nucleoli. The daughter cells typically had different numbers of nucleoli. At the same time, using immuno-FISH with probes for chromosomes 14 and 15 in HeLa cells, we found that the cell pairs with identical combinations appeared significantly more frequently than predicted by the random model. Thus, although the total number of chromosomes associated with nucleoli is variable, our data indicate that the position of the NOR-bearing chromosomes in relation to nucleoli is partly conserved through mitosis.     

甘蓝型油菜与诸葛菜属间杂种后代非整倍体类型及细胞遗传学研究

在甘蓝型油菜与诸葛菜属间五倍体杂种后代中,鉴定出多种非整倍体类型。在P3群体中,细胞学观察发现诸葛菜染色体替代甘蓝型油菜的1对染色体异代换植株,体细胞由36~38条染色体的3种类型组成,但具38条的体细胞与花粉母细胞（PMC）占绝对优势,育性正常。在P4群体后代中鉴定出3株具有37条染色体的单体类型,形态与结实率均不相同。其中1株生长势很强,其体细胞与PMC均由多种类型构成,但具37条的体细胞与花粉母细胞占主要比例,未配对的染色体形态较小,对生长无明显影响。在染色体数为44与41的两种超倍体（P3群体）后代,鉴定出具有29~32条染色体的4种非整倍体,除染色体数为29的植株外,其余均为混倍体,它们的减数分裂异常,花粉育性低。本文对这些非整倍体的来源和应用的前景进行讨论。     

Partial trisomy 12 and 8 with mosaicism, associated with translocation t(8;12) (p21;q13)]

A translocation affecting chromosomes 8 and 12 was detected in 11 persons of 3 generations of a family. The propositus, a child with multiple malformations, had a mosaicism consisting of (a) cells with 46 chromosomes which included the balanced translocation and (b) cells with 47 chromosomes and partially trisomic for chromosomes 8 and 12.     

Chromosome patterns of nontransformed variants from chemically transformed Balb-3T3 cells

Nine variant cell lines isolated from cloned 7,12-dimethylbenz(a) -ahthracene transformed Balb/3T3 mouse cells by treatment with FUdR had growth parameters closely resembling nontransformed cells. Chromosome analysis of the variant lines demonstrated that six variants had a diminished number and three variants had an increased number of chromosomes compared to the parental transformed cell line. All variants had unique marker chromosomes not present in the parental transformed Balb/3T3 cells. The distribution of marker chromosomes and heterochromatin suggested that the initial event in variant formation was a reduction in chromosome number with a subsequent polyploidization of the reduced chromosome complement.     

真水狼蛛染色体组型分析

蜘蛛染色体的研究是对传统蜘蛛分类方法的验证和补充。以处于囊胚期到体节期之间的蜘蛛胚胎细胞为材料,经秋水仙素处理,低渗、固定、制片及染色,对真水狼蛛的体细胞染色体进行了初步观察。结果表明:真水狼蛛的染色体数为雄性2n=26,雌性2n=28,性别决定机制为X_1X_2O。C-带分析表明;所有染色体均为端着粒染色体,端部有特异性染色质存在。     

Quantitative initiation of microtubule assembly by chromosomes from Chinese hamster ovary cells

The microtubule nucleating capacity of chromosomes was tested in vitro in lysates of Chinese hamster ovary cells. Colcemid-blocked mitotic cells were lysed with the detergent Triton X-100, incubated with exogenous porcine brain tubulin, attached to electron microscope grids and observed as whole-mounts. Under suitable conditions, greater than 98% of the chromosomes gave rise to microtubules at their kinetochore regions, thus unequivocally demonstrating that chromosomes are competent to initiate specifically microtubule formation. The average number of microtubules that polymerized onto a chromosome was 8 +/- 5, and greater than 36% of the chromosomes had between 10 and 19 microtubules per kinetochore region. We conclude that under the lysis conditions employed, virtually all the chromosomes retain their kinetochores, and that the kinetochores retain a substantial fraction of their microtubule nucleating capacity.     

Disomic and ditelosomic alien chromosome additions in beet (Beta vulgaris), carrying an extra chromosome of B. procumbens or telosome of B. patellaris.

Alien chromosome transmission through the female germ line as well as meiosis in pollen mother cells were studied in disomic and ditelosomic alien chromosome additions of beet. Beta vulgaris, carrying an extra pair of chromosomes or telosomes of B. procumbens or B. patellaris, respectively. The alien chromosomes carried genes for resistance to the beet cyst nematode, Heterodera schachtii, and screening for this resistance was used to select plants with or without the alien chromosomes. A great variation for alien chromosome transmission was recorded and plants carrying two extra alien chromosomes were recovered in the backcross progenies of the disomic or ditelosomic additions. However, in these progenies the average frequencies of plants without alien chromosomes (86%) did not clearly differ from that in similar progenies of the original monosomic or monotelosomic chromosome additions, indicating that doubling the number of the alien chromosome did not enlarge their transmission to the next generation. The alien chromosomes fully paired at pachytene and desynapsed again before diakinesis, indicating decreased chiasma formation. At second metaphase nearly 60% of the cells had one extra chromosome, and the remaining cells carried two or no extra chromosomes in about equal proportions. The tetrads looked fully normal. The expected relation between the average number of alien chromosomes in the germ cells and in the plants of the progenies did not show up, indicating a strong selection favouring the female gametes without alien chromosomes.     

Germ line-restricted supernumerary (B) chromosomes in Eptatretus okinoseanus.

Cytogenetic studies were performed on two types of Japanese hagfish (Eptatretus okinoseanus) that eliminate about 45% (type A) and 55% (type B) of their DNA from presumptive somatic cells during the differentiation of somatic cells. The observations revealed inter- and intraindividual variations in the number of chromosomes in germ cells of both types of hagfishes. Although the modal number of chromosomes in the germ cells was 54 in both types, the percentage of cells with the modal number was rather low (38.6% [51/132] in five specimens of type A and 22.7% [25/110] in eight specimens of type B). In addition, one of seven type B specimens clearly had a modal number of 62 chromosomes. Another specimen of type B had a bimodal distribution of chromosome numbers, with peaks of 54 and 59 chromosomes. The observation of interindividual variations was supported by data on the amount of DNA in germ cells of type B specimens. However, these variations were rarely observed in somatic cells. These results suggest that supernumerary (B) chromosomes are maintained in germ cells and are eliminated together with some other chromosomes and/or chromatin from somatic cells.     

The somatic chromosomes of a wild population of rats: numerical polymorphism

The karyotype and quantitative characteristics of a wild population of rats, Rattus rattus, were studied. Individuals of the population were classified into three distinct groups, each with a characteristic chromosome number of 38, 42 and ± 54 respectively. The frequency distribution of the three groups of rats in the sample studied was as follow: group I with 38 chromosomes formed 14%, group II with 42 chromosomes formed 54% and group III rats have had chromosome numbers varying between 50–60 formed 32%. The rats with 38 chromosomes had two pairs of marker chromosomes (2 long metacentric pairs). Those of group III were characterised by having a marked decrease or complete absence of short metacentric chromosomes with a simultaneous increase in the frequency of short telocentric chromosomes. Group II rats had more or less the chromosomal characteristics established for laboratory rats studied by previous workers. The total chromosomal length of somatic cells in either group I and II were found to be similar. The notable chromosomal polymorphism in number was explained in terms of centromeric fusion or dissociation.     

The behavior of centrosomes in multinucleate cells formed after colcemid treatment

Multinucleate PtK1 cells were generated by treating the cells with colcemid for up to 60 h. Cells with scattered chromosomes reconstructed nuclear envelopes around these chromosomes. After recovery of up to 36 h these multinucleate cells went into mitosis. In such cells mainly two types of spindles are found: a bipolar spindle with some "accessory" half-spindles and multipolar mitotic apparatus with several equally-sized half-spindles ordered in an irregular way. Ultrastructural studies revealed centrosomes within such spindles which had not developed a microtubular connection to chromosomes and obviously could not act as mitotic pole. This result is interpreted in the way that centrosomes undergo a maturation cycle. Immature centrosomes cannot form mitotic poles. The asynchrony of the cycles of the multiple centrosomes seems to be generated by an uneven distribution of special factor(s).     

Frequency of satellite association of human chromosomes is correlated with amount of Ag-staining of the nucleolus organizer region.

Methaphase chromosomes from karyotypically normal adult humans (three males, six females) and one male with a 13p - chromosome were stained by quinacrine and then by the Ag-AS silver staining method to reveal nucleolus organizer regions (NORs). Each person had a characteristic number of Ag-stained chromosomes per cell, always fewer than 10. Determination of the mean Ag-size of each chromosome showed that each of the 10 individuals had a unique distribution of Ag-stain. Within each individual, there was some variation from cell to cell in the number of acrocentric chromosomes that were Ag-stained; this was not random, and the same chromosomes (those that had at most a small amount of Ag-stain) tended to be unstained in every cell. Satellite associations were scored on the same cells. Chromosomes that had no Ag-stain were involved in satellite association less than 20% as often as those that had some Ag-stain. Chromosomes that had a small amount of Ag-stain were involved in association about 50% as often as those that had a large amount of stain. Regression analysis of the 50 (of a total of 100) acrocentric chromosomes which could be individually identified by quinacrine markers showed that the frequency with which a chromosome was involved in satellite association was strongly correlated with the amount of Ag-stained material in the NOR.     

Analysis by BrUdR-labelling technique of induced aneuploidy in mammalian cells in culture

To study the origin of induced aneuploid cells, the BrUdR-labelling technique was applied to V79/AP4 Chinese hamster cells treated with colcemid or benomyl. In this way we were able to recognize the cells which had undergone one cellular division after the treatment since their chromosomes exhibited sister-chromatid differentiation. The results showed that the induced aneuploid cells can have either a few or numerous additional chromosomes depending on the concentrations of the drug. Moreover, it could be established that aneuploid cells with numerous additional chromosomes were obtained mainly when polyploid cells were also present in the treated population. This strongly suggests that the excess of additional chromosomes found in the aneuploid cells induced by the highest concentrations may be derived by disturbances of the whole mitotic apparatus rather than by a multiplicity of errors affecting individual chromosomes.     

Numerical chromosome variation and mitotic segregation defects in the adult brain of teleost fish

Teleost fish are distinguished by their enormous potential for the generation of new cells in both the intact and the injured adult brain. Here, we present evidence that these cells are a genetic mosaic caused by somatic genomic alteration. Metaphase chromosome spreads from whole brains of the teleost Apteronotus leptorhynchus revealed an euploid complement of 22 chromosomes in only 22% of the cells examined. The rate of aneuploidy is substantially higher in brain cells than in liver cells, as shown by both metaphase chromosome spreads and flow cytometric analysis. Among the aneuploid cells in the brain, approximately 84% had fewer, and the remaining 16% more, than 22 chromosomes. Typically, multiple chromosomes were lost or gained. The aneuploidy is putatively caused by segregation defects during mitotic division. Labeling of condensed chromosomes of M-phase cells by phosphorylated histone-H3 revealed laggards, anaphase bridges, and micronuclei, all three of which indicate displaced mitotic chromosomes. Quantitative analysis has shown that in the entire brain on average 14% of all phosphorylated histone-H3-labeled cells exhibit such signs of segregation defects. Together with the recent discovery of aneuploidy in the adult mammalian brain, the results of the present investigation suggest that the loss or gain of chromosomes might provide a mechanism to regulate gene expression during development of new cells in the adult vertebrate brain.     

Satellite association of the nucleolar chromosomes in a plant

Summary A method for preparing chromosomes that included enzyme maceration and subsequent flame-drying allowed us to easily detect satellite association in the mitotic cells ofNothoscordum fragrans (2 n=19), which has six acrocentric nucleolar chromosomes in its chromosome complement. Of 593 metaphase plates examined, approximately 60% had satellite association. The number of chromosomes involved in the association varied from two to six, and the incidence decreased as the number of chromosomes involved in the association increased. Comparison of the same chromosomes stained with Giemsa and subsequently with silver demonstrated that the nucleolar organizing regions (NORs) that responded almost negatively to Giemsa and positively to silver was responsible for satellite association. The nucleoli may strongly correlate with satellite association since persistent nucleoli associated with a few metaphase chromosomes were sometimes found and the nucleoli had a strong tendency to fuse with each other at interphase. Four types of acrocentric chromosomes could be discriminated on the basis of the bands negatively staining with Hoechst. All four types were involved in satellite association and there were significant deviations from the expectation for random participation in the association.