Haplo-diploid locust embryos arising by accidental thelytoky in Chortoicetes terminifera investigated by G-banding

Two mosaic sibling embryos of the Australian plague locust, Chortoicetes terminifera are reported with haploid and diploid cell lines in widely differing proportions. One small chromosome pair involved in the two cases has alternative morphology and a B-chromosome is present in one. In addition, G-banding identifies two medium-sized chromosome pairs and alternative states of a second small pair. Using these markers it is clear that both diploid cell lines are homozygous for the chromosomes of the corresponding haploid line. These embryos have thus developed by accidental parthenogenesis from haploid cells, some of which were duplicated by endomitosis after development began.     

水稻染色体G—带的研究

用改良的ASG法首次在籼稻(O.sativa subsp.indica)品种珍汕97和粳稻(O.subsp.iaponica)品种秀岭的有丝分裂染色体上显示了G-带,并作了相应的G-带核型分析。就同一材料来说,随着有丝分裂时期的推进,染色体上带纹数目逐渐减少。籼、粳亚种间相对应的同源染色体上G-带带纹特征彼此相似。讨论了水稻G-带带型与染色体不同区域分化的关系;G-带带型与籼、粳稻分歧的关系;以及G-显带的方法。     

达乌尔黄鼠显带染色体的研究

达乌尔黄鼠分布在我国北方及蒙古和苏联等区域,对牧草及农田危害甚大。有关达乌尔黄鼠的核型国内外已有报道(Lyapunova等,1970;蔡有余等,1985;马继霞等,1985)。签于其染色体的一些特征,达乌尔黄鼠有可能成为染色体工程及检测环境诱变剂等方面的实验材料。虽然苏联Lyapunova等(1978,1980)对黄鼠属某些种的G-带和C-带进行过比较研究,我国蔡有余等(1985)对达乌尔黄鼠的C-带和Ag-NOR进行了观察,但无法对其染色体进行逐个地准确识别,特别是对Χ染体色的正确识别。为此,我们对达乌尔黄鼠的显带染色体进行了较详细的研究。     

Cytogenetic characterization of a supernumerary chromosome segment and of B-chromosomes in Astyanax scabripinnis (Teleostei, Characidae)

The chromosome complement of a local population of Astyanax scabripinnis in Brazil was investigated with emphasis on the study of the heterochromatin attached to the A-chromosomes and present in the macro B-chromosome. Analysis after C-banding, silver and CMA₃ staining, incorporation of 5-bromo-2′-deoxyuridine and chromosome digestion with nine restriction endonucleases revealed that the heterochromatin in the B-chromosomes was different from that found in the A-chromosomes. A polymorphism due to the presence of a supernumerary heterochromatic chromosome segment was observed in the population investigated. Some aspects related to the origin of the heterochromatin polymorphism in Astyanax scabripinnis are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Karyotypic characterization of Iheringichthys labrosus (Pisces, Pimelodidae): C-, G- and restriction endonuclease banding

Various chromosomal banding techniques were utilized on the catfish, Iheringichthys labrosus, taken from the Capivara Reservoir. C-banding regions were evidenced in telomeric regions of most of the chromosomes. The B microchromosome appeared totally heterochromatic. The restriction endonuclease AluI produced a banding pattern similar to C-banding in some chromosomes; the B microchromosome, when present, was not digested by this enzyme and remained stained. G-banding was conspicuous in almost all the chromosomes, with the centromeres showing negative G-banding. When the restriction endonuclease BamHI was used, most of the telomeres remained intact, while some centromeres were weakly digested. The B chromosome was also not digested by this enzyme. The first pair of chromosomes showed a pattern of longitudinal bands, both with G-banding and BamHI; this was more evident with G-banding. This banding pattern can be considered a chromosomal marker for this population of I. labrosus.     

Analysis of heterochromatin by combination of C-banding and CMA3 and DAPI staining in two fish species (Pimelodidae,Siluriformes)

The chromosomes of Steindachneridion sp. (2n = 56) and Rhamdia quelen (2n = 58) were analyzed by C-banding (CB) and Chromomycin A₃ (CMA₃) and 4,6-diamidino-2-phenylindole (DAPI) staining, separately and consecutively, in order to understand the role of base-specific fluorochrome treatment after CB. Both species' chromosomes shared common staining profiles as follows. CB with Giemsa (CBG) revealed weak heterochromatic blocks in the telomeric regions of some chromosomes and conspicuous bands on the short arms of one chromosome pair, where nucleolar organizer regions (NORs) were evidenced by silver-staining. Without CB pretreatment, the NORs were stained conspicuously with CMA₃, but not with DAPI. The latter uniformly stained all chromosomes, but leaving the NORs pale. Combination of CMA₃ or DAPI staining with CB showed distinctive fluorescent blocks in the NOR-bearing short arms of the single chromosome pair along with several bright fluorescent signals on other chromosomes, which were not evidenced by single CMA₃ or DAPI staining. These results suggest a modification of chromatin structure by CB treatment, which may increase the stainability of CMA₃ and DAPI.     

黄颡鱼染色体的C─带、Ag—NORs、荧光带和复制带显带的研究

采用Giemas染色、C─带、Ag—NORs、荧光染色和复制带显带的技术对黄颡鱼染色体进行了研究。结果表明,黄颡鱼只有部分的染色体呈现阳性C─带,可分为三类,其中NORs区是染色最深、染色面积最大的区域,为深染居间C─带。其Ag－NORs位于m5q末端。CMA3染色显示NORs区呈现出明亮的荧光。中复制染色体上着丝粒区、端粒区和居间区浅染。发现核仁缢痕、深染居间C─带、Ag—NORs、CMA3明亮区和中复制带浅染NORs区位置基本一致,C─带阳性区和中复制带浅染区具有对应性。     

Chromosome organisation in the Australian plague locust Chortoicetes terminifera

In Chortoicetes terminifera 45 independently-occurring B-chromosomes were tested and 23 distinct banding variants were detected with either G- or C-banding; six types were found more than once. In particular the Type I banding morph was detected 12 times indicating that individuals carrying this type may be under a different regime of selection compared with individuals bearing other types of banding morph; or the Type I may be subjected to a higher rate of meiotic drive in either or both sexes than other types. Also the Type I appeared to be obviously related to four other banding morphs whereas most types were not obviously related to any other banding morphs, but a few were similar in banding pattern to one or two other types. Three types of B-chromosomes were found in three or more different populations. A relatively high frequency of the Type I banding morph was found in one population, which was probably mainly composed of non-migratory individuals, and also in a laboratory-raised population. The most likely mechanisms for small changes in the banding sequence of the B-chromosomes are three-break insertions which are often indistinguishable from inversions. Rearrangements which add or delete bands, or sequences of bands, to or from B-chromosomes are probably the result of exchanges which are now known to take place in rare individuals with two B-chromosomes. The most distal region of all the banding morphs of the B-chromosome in C. terminifera, plus a short interstitial region in some types, is not late-replicating and has the banding characteristics of euchromatin. The rest of the chromatin of the B-chromosomes is heterochromatic and is the latest replicating heterochromatin in the whole genome. It consists of G-bands, which are also deeply stained with C-banding, and alternating G-interbands, which in turn are stained grey with C-banding. Both of these staining combinations are seen in heterochromatin of the normal complement. The heterochromatin of the B-chromosomes is condensed throughout 1st meiotic prophase in the male and in all somatic interphase nuclei where it can be quickly detected using the G-banding technique. The B-chromosome has a relatively constant, acrocentric morphology with a tendency to increase of length of the long arm as band numbers increase. Isochromosomes of the long arm have been seen only in laboratoryraised embryos. From egg pods with significantly fewer than expected B-chromosomes it is strongly suggested that more than one male may fertilize the eggs in a single pod.     

Differential Giemsa staining of heterochromatic B-chromosomes in Myrmeleotettix maculatus (Thunb.) (Orthoptera: Acrididae)

A modified Giemsa staining technique has been used to investigate the karyotype of the grasshopper Myrmeleotettix maculatus, since this stain appears to be diagnostic for certain repetitive DNAs. The centromeric regions are densely heterochromatic, and further heterochromatic bands occur on the X-chromosome and on both arms of the B-chromosome. The significance of these results is discussed in relation to centromeric structure and B-chromosome structure in this insect, and a possible origin of the B-chromosome is suggested.     

A cytogenetic analysis in Psophus stridulus (L.) (Orthoptera: Acrididae): B-chromosomes and abnormal spermatid nuclei

The male chromosome complement of Psophus stridulus (L.) (Orthoptera: Acrididae) has been analyzed by using orcein staining, C-banding and silver impregnation. During spermatogenesis only one pair of autosomes (M₉) shows an active nucleolar organizer region located in a C-banded constriction. There are other chromosome pairs with constrictions but these do not show nucleolar activity. The relationship between these constrictions and the C-banding pattern exhibited by this species is analyzed.In a sample of 83 males from five populations, two different supernumerary chromosomes were observed. Four males had a metacentric B-chromosome (B^m) similar in size to the sex chromosome and mitotically stable. Its meiotic behaviour indicates that it is an isochromosome. An additional small B-chromosome (B⁸) was also found in a single follicle of one individual carrying the B^m.A high rate of abnormal spermatids (macrospermatids) was scored in the individuals carrying B's. This proportion is notably higher in the follicle containing both the B^m and the B⁸.     

The chromosome banding pattern in two cytotypes (2n = 36 and 38) of blind mole rats from Turkey (Mammalia: Spalaxidae)

Two cytotypes (2n = 36 and 38) of blind mole rats, Nannospalax xanthodon (Nordmann, 1840), from the Ayd?n and Manisa provinces in Turkey were investigated. Conventional chromosome staining, Ag-NOR staining and C-banding analysis were carried out. From the cytogenetic point of view, the particular phylogenetic position of these populations is supported by their low diploid numbers only, and the Cbanding pattern and the NORs distribution seem generally similar to populations with higher chromosome numbers. Several autosomal pairs with centromeric dark Cbands were observed in the 2n=36 cytotype. One autosomal pair possessed an interstitial dark C-band on the short arm; another pair possessed an interstitial dark Cband on the long arm. Whole C-heterochromatic short arms were observed in three subtelocentric autosomal pairs in the 2n=38 cytotype. Most of the other autosomal pairs possessed centromeric dark C-bands. Distinct dark C-bands were observed also in the presumed X chromosomes of both the cytotypes. The Ag-NOR regions were found on three autosomal pairs of both the cytotypes. These sites were located in telomeric areas of the short arms of two subtelocentric and one submetacentric pair.     

Supernumerary heterochromatic segments associated with the nucleolar chromosomes of Pyrgomorpha conica (Orthoptera) contain methylated rDNA sequences

The two nucleolus organizing chromosome pairs of the grasshopper Pyrgomorpha conica can carry a proximal supernumerary heterochromatic segment. We employed different cytological techniques to characterize and analyze the possible origin of this segment. The supernumerary segment and the nucleolus organizing regions (NORs) show similar responses after C-banding plus either Giemsa or acridine orange, and chromomycin A₃/distamycin A staining to detect GC-rich chromosome regions. Fluorescence in situ hybridization with a biotinylated rDNA probe demonstrated that the segment originated by amplification of the rDNA genes. However, as the silver staining indicates, the ribosomal genes present in the segment are not active since no nucleolus is formed. The use of in situ digestion with the isoschizomeric MspI and HpaII restriction endonucleases and subsequent Giemsa, ethidium bromide or chromomycin A₃/distamycin A staining, suggests that the segment has been inactivated by DNA methylation.     

Supernumerary chromosome system,C-banding pattern characterization and multiple nucleolus organizer regions in Moenkhausia sanctaefilomenae (Pisces,Characidae)

Chromosomes of Moenkhausia sanctaefilomenae (10 males and 20 females) collected from a tributary of the Tietê River (Botucatu, S.P. Brazil) were examined using kidney and testicular cells. Both males and females presented 2n=50 chromosomes and 1 to 8 small supernumerary microchromosomes. C-banding demonstrated positively stained heterochromatic blocks in almost every chromosome and a pattern of interstitial bands located in the same position in relation to the centromere on the long arm of a large number of chromosomes. Two large NORs were detected in pair 19 of all the silver-stained metaphases; zero to 6 additional small NORs were detected in other chromosomes. A general survey of the occurrence of supernumerary chromosomes in fishes is presented.     

Trypsin G- and C-banding for interchange analysis and sex identification in the chicken

The trypsin banding methods were applied to feather pulp and embryonic material of the chicken. Two contrasting types of chromosomal banding patterns were obtained by varying the duration of trypsin treatment. A short time treatment shows a G-banding pattern which has characteristic and distinctive bands along the chromosome arms. Prolonging the trypsin treatment causes the G-banding pattern to disappear, and only the centromeres and the W chromosome remained heterochromatic which is characteristic of the C-banding pattern. The application of the G-banding pattern analysis was used to identify regions of chromosomes involved in rearrangements. The simplified trypsin technique which produces the C-banding pattern makes it relatively easy to identify the W sex-chromosome and determine sex in avian species.     

Studies of Chromosome Banding with Giemsa in Vicia faba and Allium cepa

Giemsa dye is a complex mixture containing methylene blue, its oxidation products-azure Ⅰ, Ⅱ, Ⅲ, and their eosinate. The results of our experiments have demonstrated that staining with methylene blue alone can give a faint trace of banding as well as azure Ⅰ, Ⅱ. No bands are obtained with eosin. Nevertheless, good chromosome bandings can be often produced by staining with methylene blue-eosinate or azure Ⅱ-eosinate. These data indicate that eosinate has an important effect for the formation of C-banding on plant chromosomes. In our experiments, the treatments of chromosomes with trypsin or papain have also resulted in good C-banding pattern when slides are stained with Giemsa. We found that the slides untreated with proteinase showed homogeneous intense chromosome staining and, on the contrary, the slides treated with proteinase led to palestaining chromosomes and presenting bandings. It has shown that proteinase, especially trypsin, not only can remove a large amount of chromosomal protein but also can remove DNA and results in C-bandings. Treated properly with trypsin and followed by the Feulgen staining, chromosomes can also produce the C-bandings, but chromosomes treated overtime with trypsin are stained more palely in Feulgen reaction or lead to colourlessness. The above results have further proved that trypsin technique removes large amounts of chromosome DNA and removes less from the C-band regions than from the non-band regions. In this paper we mainly discussed the effects of protein on mechanism of plant chromosome banding. We consider that the production of plant C-banding is probably due to the differential accessibility of nucleoprotein between euehromatin and heteroehromatin regions. It brings about selective removal of nucleoprotein from the chromosome arms. We have compared the effect of trypsin with papain and pepsin on producing bands. Good bands are produced by Giemsa staining chromosomes with trypsin, but no bands are obtained by staining chromosomes treated with pepsin. So the results have expressed that histones are possibly playing more important role in C-bandings.     

Constitutive heterochromatin,G-bands and nucleolus-organizer regions in four species of Didelphidae (Marsupialia)

Chromosomes of Didelphis albiventris, D. marsupialis, Philander opossum and Lutreolina crassicaudata, four species of marsupials with very similar karyotypes and 2n=22 were studied. All the chromosomes were acrocentrics except the X in L. crassicaudata, which is a metacentric.The G-band patterns of these species are similar but the distribution of constitutive heterochromatin differs among them as shown by C-banding. The hypothesis that the X in L. crassicaudata might be an isochromosome derived from the acrocentric X in the other species is discarded since G-and C-banding patterns differ in the two arms.In D. marsupialis the Ag-NORs are terminal and located in both arms of one pair and in the long arms of two pairs of medium-sized autosomes. In P. opossum the NOR-bearing chromosomes could be precisely identified through simultaneous silver staining and G-banding. The Ag-NORs are terminal and located at the short arm of pair 5 and the long arm of pair 7.     

茅舍血厉螨核型及染色体的C带、G带的研究

本文首次报道了一种革螨——茅舍血厉螨核型及染色体C带、G带的研究。用剖腹取卵法、玻璃纸压片、Giemsa染色,经分析茅舍血厉螨的核型,单倍体n=7,二倍体2n=14。 用氢氧化钡—吉姆萨技术显示茅舍血厉螨染色体C带。在第1、2、4、5染色体上出现恒定的C带部分,第3、6、7染色体上出现不恒定的C带部分。根据C带带型,茅舍血厉螨着丝点的位置可分为近中区域(sm),近端区域(St),末端区域(t)和末端点(T)四类。 G带分析用胰蛋白酶—吉姆萨技术显示。 本文对茅舍血厉螨的核型、革螨染色体研究中螨卵的收集方法和染液的改进、C带带型与着丝粒位置的确定和G带显带问题进行了讨论。     

Nucleolus organizer regions and heterochromatin in the zebu (Bos indicus L.)

Summary Ag-NOR staining and a counterstain enhanced fluorescence technique (chromomycin A₃/distamycin A/DAPI-staining = CDD-method) and G-banding, respectively, have been applied to the zebu (Bos indicus L.) chromosomes. The nucleolus organizer regions (NORs) were found in the telomeric regions of chromosomes nos. 2, 3, 4, 11, and 28. CDD staining led to a well-defined R-banding pattern along the chromosome arms and to the visualization of centric heterochromatic bands of variable sizes.     

C- and G-bands of the opossum chromosomes: terminal sequences of DNA replication.

The sex chromosomes of the opossum, Didelphys virginiana, are the only elements that exhibit C-banding. In contrast, the sex chromosomes as well as the autosomes bear specific G-Bands. However, unlike other mammalian species different types of G-banding are observed if the chromosomes are pretreated with trypsin and SSC solution The SSC-pretreated chromosomes show discrete bands only when stained with Giemsa at certain pH values. An asynchronous pattern of terminal DNA replication is observed among the three C-banding regions of the X-chromosome. The inter- and intrapositive G-banding areas of the chromosomes are not always late in DNA replication in comparison to those negatively stained G-banding areas.     

C,Q and H-banding in the analysis of Y chromosome rearrangements in Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

In Lucilia cuprina C-banding produces procentric bands on all autosomes and deep staining over most of the X and Y chromosomes which conciderably facilitates the analysis of complex Y chromosome rearrangements. The Y chromosome is generally darkly C-banded throughout while in the X chromosome a pale staining segment is found in the distal portion of the long arm. Modulation of the banding reaction results in grey areas in both X and Y. When C-banding is compared with allocycly it is clear that not all heteropycnotic regions in the sex chromosomes C-band to the same extent. Secondary constrictions in the short arms of both X and Y chromosomes are clearly revealed by C-banding, the X satellite being polymorphic for size.— Q-banding results in a brightly fluorescing band in the short arm of structurally normal Y chromosomes. This band loses its fluorescence in some translocations, probably through a position effect. Hoechst 33258 staining does not produce any brightly fluorescing bands.