粳稻三体的染色体G—显带鉴定

采用有丝分裂染色体的G-显带技术,对供试的6个三体的额外染色体进行了鉴定。结果表明:A型、B型、C型、D型、E型和H型三体的额外染色体分别为K5、K6、K12、K7、K8和K10。用不同的分裂时期的细胞所鉴定出的结果完全一致。与过去所用的三体鉴定的方法相比较,利用G-显带技术鉴定三体的方法具有准确性高,稳定性和重复性好以及简便易行的优点。     

Asymmetric distribution of mitochondria and of spindle microtubules in opposite directions in differential mitosis of germ line cells in Acricotopus

Additional chromosomes present only in the germ line are a specific feature of the Orthocladiinae, a subfamily of the Chironomidae. During the complex chromosome cycle in the orthocladiid Acricotopus lucidus, about half of the germ-line-limited chromosomes (Ks) are eliminated in the first division of the primary germ cells. Following normal gonial mitoses, the reduction in the number of Ks is compensated for, in the last mitosis prior to meiosis, by a monopolar movement of the unseparated Ks, while the somatic chromosomes (Ss) segregate equally. This differential mitosis produces daughter cells with different chromosome constitutions and diverse developmental fates. A preferential segregation of mitochondria occurs to one pole associated with an asymmetric formation of the mitotic spindle. This has been detected in living gonial cells in both sexes by using MitoTracker probes and fluorochrome-labelled paclitaxel (taxol). In males, the resulting unequal partitioning of mitochondria to the daughter cells is equalised by the transport of mitochondria through a permanent cytoplasmic bridge from the aberrant spermatocyte to the primary spermatocyte. This asymmetry in the distribution and in the segregation of cytoplasmic components in differential gonial mitosis in Acricotopus may be involved in the process of cell-fate determination. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

玉米染色体G-带ASG法显带的研究

两个自交系的根尖染邑体经ASG法处理显出了G-带。王米G-带沿整个染色体长轴分布,是一些密切邻近的多重带纹。无论有丝分裂的晚前期、早中期或中期染色体都有这类带纹。每一对同源染色体的两成员G-带带型基本相似,不同染色体或同一染色体的不同区域带纹具有一定的差异。ASG处理前用α-溴萘或放线菌素D预处理都可显出G-带。本文讨论了玉米G-带与哺乳动物G-带的相似点以及用ASG法进行玉米G-带显带应注意的技术问题。     

The effect of chromosome banding techniques on the proteins of isolated chromosomes

Experiments were undertaken to determine the effect of various chromosome banding treatments on the histone and nonhistone proteins of isolated, fixed, air-dried metaphase chromosomes. Chromosome preparations were exposed to G-banding (SSC, urea, NaCl-urea, or trypsin), R-banding (Earle's balanced salt solution), and C-banding (NaOH or Ba(OH)₂) treatments, and the extracted and residual proteins were examined by SDS polyacrylamide gel electrophoresis. The results indicate that each of the banding treatments induce characteristic alterations in the chromosomal proteins. The residual proteins left in chromosomes after the diverse G-banding treatments were generally similar to one another, indicating that treatments inducing the same type of banding have similar effects on the chromosomal proteins. This was also true for the two different C-banding treatments. On the other hand, the residual protein patterns seen after the G-banding treatments were strikingly different from those seen after R-banding, which in turn differed from those seen after C-banding. The treatments inducing different types of banding therefore produce markedly different effects on the chromosomal proteins. These protein alterations may have an important influence on the induction of chromosome bands.     

大麦G—显带核型的研究

本文报道了 ASG 法处理的三个栽培大麦(Hordeum Vulgare)品种 G-带的核型研究。结果表明无论是早中期或中期染色体都显示出了密切邻近的、多重的 G-带带纹。在有丝分裂过程中染色体愈浓缩带纹数目愈少。同源染色体之间带纹分布的位置、染色深浅以及带纹数目都基本一致,可以较为准确地进行配对。同一分裂时期不同染色体的 G-带带纹各具一定的特点,可以作为鉴别的标记。讨论了显带技术和中期染色体的 G-带等问题。     

Studies on G-Banding Karyotype in Barley (Hordeum vulgare)

G-banding karyotypes of three cultivars in barley were analyzed. Multiple closely adjacent G-bands were able to be observed in each early metaphase or metaphase chromosome treatted by an ASG method. The more concentrated the chromosome, the less was the number of G-bands during mitosis. The position of band distribution, staining degree and band numbers between homologous chromosomes were basically identical. Chromosome pairing for karyotype analysis could be carried out more accurately. G-banding patterns of different chromosome pairs were not the same, they could be used as the markers to distinguish one from another chromosome pair. During the same mitotic stage the banding patterns including number, relative position and staining degree of the bands between different cultivars were basically the same, but they had differences in the size and staining degree of some bands near centromeres. G-banding technique and G-banding of metaphase chromosomes were discussed.     

Chromosomal rearrangements in rock wallabies, Petrogale (Marsupialia: Macropodidae). VI. Determination of the plesiomorphic karyotype: G-banding comparison of Thylogale with Petrogale persephone, P. xanthopus, and P. l. lateralis.

G-banding has demonstrated the presence of a conserved (2n = 22) chromosome complement in the macropod genus Thylogale and in some Petrogale species. This plesiomorphic karyotype consists of acrocentric chromosomes 1, 2, 5, 6, 8, 9, and 10; submetacentric chromosomes 3 and 4; and a metacentric chromosome 7. It should now be possible to relate the G-banding patterns of all other Petrogale species to this plesiomorphic complement and thereby determine the number and types of changes that have occurred during the course of chromosome evolution in Petrogale. It is hypothesised that this 2n = 22 complement is plesiomorphic for all macropodids.     

BrdU处理的鱼类染色体高分辨G-带带型分析

本文应用鱼类染色体高分辨G-带技术,重点将黄鳝培养细胞具不同长度染色体的正中期分裂相做成G-带核型加以比较分析。随着染色体长度的增加,带纹数目也增加。但增加是有限度的。染色体带纹数目的增加,明显地表现在深染带再分为若干亚带。当染色体从前期向中、后期过渡收缩变短时,一些亚带融合为原来数目的带。染色体上各个带的收缩程度、收缩时间是不均等的。实验证明大剂量的BrdU不仅能阻断鱼类细胞于中S期,也可使染色体伸长、小剂量的伸长作用不明显。最后讨论了BrdU处理与G-显带的关系、染色体带纹数目相对恒定以及染色体伸长缩短问题。     

Chromosome pairing in the oögonial cells of Drosophila melanogaster

Pairing between two nonhomologous chromosomes, one a free X-duplication and the other a free fourth chromosome, has been observed cytologically with high frequencies in the oögonial cells of Drosophila melanogaster. The frequencies of nonhomologous pairing ranged from 27 to 47% and showed a positive correlation with the similarity in size between the two participating nonhomologues. Partial homology increased pairing frequency between nonhomologues in the oögonial cell, in contrast to the behavior of the same nonhomologues at distributive pairing in the oöcyte, where pairing is strictly size-dependent. Pairing between homologues in the same oögonial cells occurred at a frequency of only 71% and was higher for the autosomes (73%) than for the sex chromosomes (66%). An increased frequency of homologous pairing was found for older gonial cysts (4-cell, 72.0% ; 8-cell, 76.1%) as compared with younger cysts (1-cell, 59.1% ; 2-cell, 53.1%).Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation.     

A note on the karyotypes and chromosome associations of the Hylobatidae, with special reference to Hylobates (Nomascus) concolor

The somatic chromosomes, obtained from short term leukocyte cultures, were studied of four species of the Hylobatidae: Hylobates lar, H. agilis, H. (Nomascus) concolor and Symphalangus syndactylus. In accordance with earlier observations by others, the diploid chromosome numbers were found to be 44 in both Hylobates lar and H. agilis, 52 in H. concolor and 50 in Symphalangus syndactylus. The chromosome associations observed in metaphase spreads are clearly different in the three types of chromosome complements. In Hylobates lar and H. agilis associations are found between both members of the marked chromosome pair. In Symphalangus syndactylus the only two acrocentric elements of the karyo-type, which are of medium size, associate frequently. In H. concolor finally, the members of three pairs of small acrocentrics are involved in chromosome associations. G-banding patterns (obtained by trypsin treatment) showed that in a male individual of this species also the small acrocentric Y chromosome sometimes participates in these associations. The evolutionary aspects of these observations are briefly discussed.     

G-band homology and C-band variation in the Japanese mustelids,Mustela erminea nippon andM. sibirica itatsi

The diploid number(2n)and fundamental number (FN) were 44 and 64 inMustela erminea nippon and 38 and 64 inM. sibirica itatsi. In spite of such a marked dissimilarity in their chromosome constitution, most of the chromosomes of these two species showed high G-band homology. On the other hand, interspecific variations in the amount of C-heterochromatin were observed in several pairs of chromosomes which were regarded, based on their G-banding patterns, to have arisen from a common origin. Some of the chromosome pairs associated with the C-heterochromatin variations showed significant differences in length or arm ratio, whereas others did not. These findings strongly indicate that the G-banding patterns might have been well conserved, at least in the euchromatic regions, through the speciation process; in contrast, C-heterochromatin showed quantitative variations, some of which could be regarded to have been formed by duplication. Thus, the karyological relationships between the Japanese ermine and the Japanese weasel could be explained by Robertsonian fusion and quantitative alteration of C-heterochromatin.     

Isolation and chromosomal localization of a germ line-specific highly repetitive DNA family in Acricotopus lucidus (Diptera, Chironomidae)

. In the chironomid Acricotopus lucidus, parts of the genome, the germ line-limited chromosomes, are eliminated from the future soma cells during early cleavage divisions. A highly repetitive, germ line-specific DNA sequence family was isolated, cloned and sequenced. The monomers of the tandemly repeated sequences range in size from 175 to 184 bp. Analysis of sequence variation allowed the further classification of the germ line-restricted repetitive DNA into two related subfamilies, A and B. Fluorescence in situ hybridization to gonial metaphases demonstrated that the sequence family is highly specific for the paracentromeric heterochromatin of the germ line-limited chromosomes. Restriction analysis of genomic soma DNA of A. lucidus revealed another tandem repetitive DNA sequence family with monomers of about 175 bp in length. These DNA elements are found only in the centromeric regions of all soma chromosomes and one exceptional germ line-limited chromosome by in situ hybridization to polytene soma chromosomes and gonial metaphase chromosomes. The sequences described here may be involved in recognition, distinction and behavior of soma and germ line-limited chromosomes during the complex chromosome cycle in A. lucidus and may be useful for the genetic and cytological analysis of the processes of elimination of the germ line-limited chromosomes in the soma and germ line. Received: 12 April 1997; in revised form 26 June 1997 / Accepted: 29 June 1997     

Banding analysis of the somatic chromosomes of the domestic dog (Canis familiaris).

The chromosomes of the domestic dog (Beagle) were investigated by several different staining techniques. G-banding, Q-banding, and the bis-benzimidazol derivative Hoechst 33258, make possible the identification of all 39 chromosome pairs. Constitutive heterochromatin (C-bands) was present on a few chromosomes as distinctive, large stained areas; on the other autosomes there was little or no heterochromatin detectable.     

X-ray induced rearrangements between germ-line limited and soma chromosomes of Acricotopus lucidus (Diptera,Chironomidae)

The germ-line limited chromosomes (Ks) [K being derived from Keimbahn (Bauer, 1970)] of Acricotopus lucidus were studied in gonial and differential mitosis. After C-banding the soma chromosomes (Ss) are stained only at their centromeric regions whereas the Ks exhibit centromeric, intercalary and terminal heterochromatin. By X-raying sperms it was attempted to transfer K sections on or into Ss in order to bring finally S-linked K sections to polytenization in the salivary glands, and to obtain more knowledge about the structure of Ks. Seven F₁-larvae were detected with K-S-rearrangements: four with insertions of heterochromatic segments, two with insertions of sections with S-homologous banding pattern and one with a translocated K chromosome part, which consists of S-homologous euchromatic sections as well as of an intercalary and a terminal heterochromatic segment. The present results strongly suggest that the Ks of A. lucidus are derived from the Ss by rearrangements and by formation and accumulation of repetitive sequences.     

Chromosome homology and heterochromatin in goat,sheep and ox studied by banding techniques

Peripheral blood lymphocyte metaphase chromosomes of three Bovoidean species have been studied using Quinacrine fluorescence and Giemsa banding techniques to give Q-, G-, and C-banding patterns. Q- and G-banding characteristics, coupled with chromosome length, enabled all of the chromosomes in each of the chromosome complements to be clearly distinguished, although some difficulties were encountered with the very smallest chromosomes. A comparison of G-banding patterns between the species revealed a remarkable degree of homology of banding patterns. Each of the 23 different acrocentric autosomes of the domestic sheep (2n=54) was represented by an identical chromosome in the goat (2n=60) and the arms of the 3 pairs of sheep metacentric autosomes were identical matches with the remaining 6 goat acrocentrics. A similar interspecies homology was evident for all but two of the autosomes in the ox (2n=60). This homology between sheep metacentric and goat acrocentric elements confirms a previously suggested Robertsonian variation. The close homology in G-banding patterns between these related species indicates that the banding patterns are evolutionarily conservative and may be a useful guide in assessing interspecific relationships. —The centromeric heterochromatin in the autosomes of the three species was found to show little or no Q-or G-staining, in contrast to the sex chromosomes. This lack of centromeric staining with the G-technique (ASG) contrasts markedly with results obtained with other mammalian species. However, with the C-banding technique these regions show a normal intense Giemsa stain and the C-bands in the sex chromosomes are inconspicuous. The amount of centromeric heterochromatin in the sheep metacentric chromosomes is considerable less than in the acrocentric autosomes or in a newly derived metacentric element discovered in a goat. It is suggested that the pale G-staining of the centromeric heterochromatin in these species might be related to the presence of G-Crich satellite DNA.     

The mechanism of C- and G-banding of chromosomes

A series of biochemical, staining and electron microscopy techniques were utilized to investigate the mechanisms of C- and G-banding. These led to the following conclusions.

1. 1. The treatment of fixed chromosomes with 0.07 N NaOH for 30 to 180 sec removes from 16 to 81% of the DNA from the chromosomes.

2. 2. On average, the complete C-band technique removes 60% of the DNA.

3. 3. This DNA is preferentially extracted from the non-C-band regions.

4. 4. In marked contrast to this, all G-band techniques (except 1) removed less than 9% of the chromosomal DNA.

5. 5. Most of the G-band techniques, including those using trypsin, remove very little protein from the chromosomes.

6. 6. Feulgen staining indicated that neither C- nor G-banding can be explained on the basis of different amounts of DNA along the length of the chromatid.

7. 7. Treatment of chromosomes with alkali or prolonged treatment with trypsin tends to destroy G-bands, while C-bands remain.

8. 8. The combined use of acridine orange and Giemsa staining indicate that, (a) repetitious DNA in situ renatures in seconds while non-repetitious DNA renatures in minutes; (b) Neither C- nor G-banding depends upon the differential renaturation of DNA for its effect.

9. 9. G-banding is more delicate and relatively mild conditions allow staining of both C- and G-bands. To obtain only C-bands the chromosome must be treated more harshly to disrupt or destroy the G-bands.

10. 10. DNA-non histone protein interactions probably play an important role in the production of both C- and G-banding.

     

Structure of human chromosomes visualized at the electron microscopic level

A newly developed technique allows cytological (light microscope level) chromosome preparations to be examined at the electron microscopic level. Ultrathin (50 nm) sections of highly condensed Hela cell metaphase chromosomes show the characteristic mitotic chromosome morphology. In addition a fibrous network (presumably chromosome fibers) can be seen within them. Fibers appear to be gathered at foci along each chromatid. Treatment of chromosomes with trypsin in a trypsin/G-banding procedure reduces the amount of staining material at the electron microscopic level and results in more prominent foci. Thicker (100 nm) sections of less condensed chromosomes prepared from human lymphocytes display a banding pattern similar to G-banding, even without pretreatment with proteases.     

The grasshopper X chromosome

The X chromosome can be identified with the light microscope throughout all stages of the gonial cell cycle (including interphase) in the grasshopper Brachystola magna. At gonial mitotic stages the X chromosome gives the appearance of being undercondensed or negatively heteropycnotic. At interphase the X projects out from the body of the nucleus. — Examination with the electron microscope reveals that the X is compartmentalized at least two gonial cell cycles prior to the entry of the cells into meiotic prophase. The membrane layers that envelope the X chromatin at interphase remain associated with the X chromosome throughout gonial mitotic stages providing the ultrastructural basis for the apparent negative heteropycnosis observed with the light microscope. — The X chromosome is inactive in RNA synthesis during gonial mitotic stages but is hyperactive in RNA synthesis when compared to autosomes at gonial interphase. — X chromosome condensation which reaches its maximum at premieotic interphase is initiated at or prior to the pre-pentultimate gonial division.