植物染色体G-带的初步研究

本文首次报道了川百台(Lilium davidii)、华山松(Pinus armardii)和七叶一枝花(Paris polyphylla)等植物染色体G-带研究结果。本试验的G-带与以往的C-带不同,C-带每条染色体上一般只有1-4条带,多分布在着丝点附近,而G-带则多达几十条,分布在整条染色体上,带纹清晰,前期染色体带呈颗粒状,中期染色体呈明显的带状,与哺乳动物染色体G-带很相似。G-带的数目取决于染色体浓缩的程度。前期染色体带纹数目是中期的三倍,接近人类高分辨带水平。对G-带带纹采用了自动光谱分析,波峰数值与带纹相符。作者同时介绍了胰酶法在植物染色体G-带中的应用。认为此方法既适合动物亦适用于植物。但植物G-带显示的关键可能不在胰酶法本身,而在合适的分裂时期及染色体处理技术。     

Studies on G-bands and Macrocoils in Plant Chromosomes

Four different methods including trypsin urea, SDS and NaOH are presented for the in situ induction of G-bands and macrocoils on the chromosomes of Secale cereale, Hordeum vulgare and Vicia faba. The bands obtained were numerous and along the whole chromosome, the number of the G-bands was much interrelated with the condensation of chromosomes. The bands of homologous chromosomes in some cells were matchable. The G-banded chromosomes in late prophase have nearly reached high resolution level. When incubation periods were beyond critical time for G-banding, macrocoils were often revealed. Gyre number changed with chromosome condensation and the direction of coils has showed different patterns. Transformation of G-bands into macrocoils was first reported in plant chromosomes. Some chromosomes showing G-bands under light microscope appeared spiral patterns under scanning electron microscope. In this paper the relationship between G-bands and macrocoils in plant chromosomes is also discussed.     

植物染色体高分辨G-带技术研究

本文对植物染色体高分辨 G-带技术进行了比较系统的研究,并首次运用改良的尿素法在野生一粒小麦、玉米、蚕豆、吊兰、川百合等多种植物上诱导出 G-带,带纹清晰,数目多,分布在染色体全长上。前期染色体带呈颗粒状,中期染色体呈明显带状,与哺乳动物染色体 G-带很相似。G-带的数目取决于染色体浓缩程度,中期染色体一条深带到晚前期可显示出2.67条亚带。作者同时比较了胰酶法与尿素法的显带效果。认为两种方法显示的带纹基本相同,尿素法比胰酶法作用温和,显带时间长达数分钟,易于掌握,重复性高,具有更高的应用价值。     

Why plant chromosomes do not show G-bands

Summary Giemsa techniques have refused to reveal G-banding patterns in plant chromosomes. Whatever has been differentially stained so far in plant chromosomes by various techniques represents constitutive heterochromatin (redefined in this paper). Patterns of this type must not be confused with the G-banding patterns of higher vertebrates which reveal an additional chromosome segmentation beyond that due to constitutive heterochromatin. The absence of G-bands in plants is explained as follows: 1) Plant chromosomes in metaphase contain much more DNA than G-banding vertebrate chromosomes of comparable length. At such a high degree of contraction vertebrate chromosomes too would not show G-bands, simply for optical reasons. 2) The striking correspondence of pachytene chromomeres and mitotic G-bands in higher vertebrates suggests that pachytene chromomeres are G-band equivalents, and that this may also be the case in plants. G-banded vertebrate chromosomes are on the average only 2.3 times shorter in mitosis than in pachytene; the chromomeric pattern therefore still can be shown. In contrast, plant chromosomes are approximately 10 times shorter at mitotic metaphase; their pachytene-like arrangement of chromomeres is therefore no longer demonstrable.     

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。     

Chromosome G—banding in plants by inducing with trypsin and urea

Clear G-bands were revealed by applying the TUG method on chromosomes of 5 species of higher plants(Lilium davidii,Viciafaba,Hordeum vulgare,Ginkgo biloba and Triticum monococcum).Some details of the TUG method which consisted of treating chromosomes with both trypsin and urea were also studied.The mechanisms that might account for the presence of G-bands in plants were discussed.     

An approach to the G-Banding Technique in Rye Chromosome

The G-banding technique has not yet been broken through in studying plant chromosomes. in this paper, we have described a new banding method in Secale cereale. The rye root tips were treated with actinomycin D (40-100 μg/ml) for two hours and with colchicine (0.01%) for 0.5 hour and then fixed with methanol-acetic acid (3:1). After cell wall degradation by cellulase and pectinase, the chromosome sample were made by a hypotonic and flame-drying method (hypotonic treatment→preparation of cell suspension→dropping suspension on slide flame-drying). Following an air-drying period of about a week, the slides were incubated in trypsin-EDTA solution (0.01–0.05%) at 30℃ for 10–15 sec. and subsequently stained with Giemsa. Lots of deep stained bands along the arms of many prophase and late prophase chromosomes were seen. The position of them was obviously different from that of the C-band and the number of them was approximately in proportion to the longitude of chromosomes. Such bands were not seen in metaphase chromosomes. We thought it preferable to use prophase chromosomes to probe G-banding technique in plant and this paper has proposed a possible way for studying G-banding technique in plant chromosome. We also discuss why metaphase chromosomes of plant do not show G-bands.     

Harlequin banding and localisation of sister-chromatid exchanges.

Harlequin banding (HB) was standardised on Indian muntjac chromosomes by superimposing harlequin staining or sister-chromatid differentiation and G-banding after incorporation of bromodeoxyuridine (BrdU) or cholorodeoxyuridine (CldU), and after treatment with BrdU plus mitomycin C (MMC). SCEs were localized on these chromosomes with the aid of the G-band map. There were more SCEs in G-bands than in R-bands in BrdU-incorporated chromosomes. CldU-incorporated chromosomes, however, did not show a preferential localization of SCEs in either G- or R-bands. When BrdU + MMC-induced SCEs were localized in harlequin-banded chromosomes, there was a significantly greater number of SCEs in R-bands; and there was a concomitant reduction in the frequency of SCEs in G-bands, as compared to the SCEs observed in this region after BrdU incorporation alone. Centromeric regions of chromosomes 1 and X had preferred sites for occurrence of SCEs in BrdU-incorporated chromosomes, the preferred sites being more in G-bands after BrdU and CldU incorporation and in R-bands after treatment of BrdU-incorporated chromosomes with MMC. Thus the formation of SCEs is not restricted by structure per se as defined by euchromatin or heterochromatin, but depends on the site of lesion production, type of lesion and repair pathway followed.     

水稻染色体标本制备的风油精法

水稻的染色体较小,不同的染色体在形态上较难区分。常规的压片技术由于很难使染色体分散,且也不能完全排除细胞质的干扰,因而很不适用于水稻染色体核型分析及显带。Kurata 等(1978)采用酶解与火焰干燥技术制备水稻染色体标本,获得清晰的染色体图象,从而成功地进行了水稻染色体的核型分析。陈瑞阳等(1982)参照人类染色体     

Induction of G-bands in Root Tip Chromosomes of the Maize

Authors tried to induce G-bands of chromosomes of root-tips in maize (Zey mays L.. everty Sturt) with a variety of technological modifications. The following techniques were found to be more satisfactory: primary root-tips were treated with an aqueous actinomycin D(AMD) solution (70 μg/ml) at room temperature; air dry slides of chromosomes in maize made the chromosomes spread well and plasma off; and then the preparations of the chromosomes were treated with modified methods of Seabright[7] and Utakoji[8] and the technique of aceto-orcin stain. The G-bands of chromosomes of corn were induced with the three methods above. They were shown in Plate 1, 2, 3 and 4 which are similar to the G-bands of chromosomes in human and mammal, and these bands are more consistent in each chromosomes.     

Relationship between patterns of late S DNA synthesis and C- and G-banding in muntjac chromosomes

In pulse-labelled muntjac chromosomes, segmental labelling corresponding to the large blocks of G-bands was observed during late S; the termination sequence of DNA synthesis was light bands → C-bands → G-bands.     

牛蛙（Rana catesbeiana）染色体高分辨带显示的初步探讨

本文报道显示牛蛙染色体高分辨带的一种方法。通过2—巯基乙醇的预处理和Ohnuki低渗液和低渗及火焰干燥可使染色体伸长并显出高分辨带纹,且这种带纹和人的高分辨G带类似。初步探讨了牛蛙染色体高分辨显带机理。     

Electron microscopy of G-banded human mitotic chromosomes

Trypsin-treated human metaphase chromosomes stained with Giemsa and uranyl acetate showed clear, reproducible band structures under the transmission electron microscope (TEM). The banding pattern observed with TEM corresponded very closely to the G-band pattern visualized by light microscopy. The TEM images were used for karyotype analyses. Trypsin-treated chromosomes stained with uranyl acetate alone also showed clear G-bands under TEM. Shadow casting in addition to uranyl acetate staining revealed more structural detail of the chromosomes. Chromosome fibers, 200 Å–300 Å in diameter, were observed in the interband regions. Most chromosomes showed the major G-bands under the higher TEM magnification wit0out any trypsin treatment.     

High-mobility group protein HMG-I localizes to G/Q- and C-bands of human and mouse chromosomes

Mammalian metaphase chromosomes can be identified by their characteristic banding pattern when stained with Giemsa dye after brief proteolytic digestion. The resulting G-bands are known to contain regions of DNA enriched in A/T residues and to be the principal location for the L1 (or Kpn 1) family of long interspersed repetitive sequences in human chromosomes. Here we report that antibodies raised against a highly purified and biochemically well characterized nonhistone "High-Mobility Group" protein, HMG-I, specifically localize this protein to the G-bands in mammalian metaphase chromosomes. In some preparations in which chromosomes are highly condensed, HMG-I appears to be located at the centromere and/or telomere regions of mammalian chromosomes as well. To our knowledge, this is the first well-characterized mammalian protein that localizes primarily to G-band regions of chromosomes.     

家猪减数分裂粗线期二价体与有丝分裂中期染色体的比较研究

以性成熟公猪睾丸和外周血为材料,采用长低渗、高氯仿卡诺固定液固定和外周血细胞培养制备减数分裂粗线期二价体和有丝分裂中期染色体,通过对二价体和有丝分裂中期染色体分裂指数和长度的比较研究,发现二价体的分裂指数和长度分别是有丝分裂中期染色体的5倍和3．42倍（1．87～5．98）;同时以12号染色体为例,比较了二价体上的染色粒结构带与有丝分裂中期染色体G－带,表明染色粒结构带比中期染色体G－带纹丰富,而与早中期G－带带织吻合。     

Relation between the SCE points and the DNA replication bands

A method for obtaining a combination of differential sister chromatid staining and DNA replication banding is described. Using this method the SCE points can be precisely localized to particular bands of individual chromosomes. It was shown, that SCEs occur not only in the regions of early DNA replication bands (=euchromatic segments=negative G-bands), but also in the regions of late DNA replication bands (=heterochromatic segments=positive G-bands). SCEs occurred about three times more frequently in the euchromatic segments than in the heterochromatic segments. Furthermore, more SCEs were observed in the early replicating X-chromosome than in the late replicating X-chromosome.     

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.     

A rapid, simple and reliable combined method for G-banding mammalian and human chromosomes

A simple and reliable method for G-banding chromosomes from human and mammalian cells is described. This rapid method combines hot saline and trypsin treatments and yields high quality G-bands in both bone marrow and cultured cells.     

The ultrastructure of G- and C-banded chromosomes

A method of visualizing chromosome bands by electron microscopy has been used to investigate the fine structural organization of G- and C-banded chromosomes. The following information has been obtained:

1. 1. G-bands, produced by trypsinization, were electron dense regions of highly packed chromatin fibres separated by regions in which the chromatin fibres were much less densely packed (interbands).

2. 2. Several degrees of chromatin dispersion were apparent in trypsinized chromosomes. Such dispersion was not a prerequisite for the initial visualization of G-bands, however the progressive pattern of dispersion indicated that the bands were relatively more resistant to dispersion than the interbands.

3. 3. After fixation and trypsinization, individual chromatin fibres measured 250 Å in diameter and appeared morphologically similar to control chromatin fibres seen by whole mount electron microscopy.

4. 4. In trypsinized chromosome complements, the chromosomes often appeared to be interconnected to one another by chromatin fibres. The evidence indicates that these interchromosomal fibres are artefacts produced by the overlapping of dispersed chromatin fibres.

5. 5. When the same metaphase chromosome was observed by both light and electron microscopy, some of the light microscopic G-bands were represented by two or more ultrastructural bands. The number of bands seen in metaphase chromosomes by electron microscopy appears to approach the increased number of bands generally seen in prometaphase chromosomes by light microscopy.

6. 6. C-banding methods (NaOH treatment or overtrypsinization) resulted in the extraction of variable amounts of chromatin from the non C-band regions of the chromosomes, however the constitutive heterochromatin remained highly condensed and resistant to extraction. This result supports the hypothesis that the mechanism of C-banding involves the selective loss of non C-band chromatin.