小冰麦异附加系中天兰冰草染色体的变异

通过对两套14种小冰麦异附加系的体细胞染色体观察,发现3个异附加系各有1对染色体发生了显著变异。其中TAl-14t有1对端着丝点染色体,TAl-22s和TAl-27s各有1对近中着丝点的小染色体。通过组胞遗传学分析,从3个方面证明了发生变异的染色体均来自天兰冰草。此外还发现在其中的两个异附加系(TAI-14t和TAl-27s)中可能产生了自发易位。     

小麦愈伤组织及再生植株的染色体变异

对培养在含有不同附加成分的MS培养基上的小麦愈伤组织染色体进行了跟踪研究。结果表明,在整个培养过程中各培养基上愈伤组织都有一定程度的染色体变异。在培养初期,高浓度2,4-D可增加愈伤组织中的染色体变异率,AgNO_3可降低染色体变异率。6-BA对培养初期愈伤组织染色体变异率没有显著影响。但高浓度6-BA可加大长期培养愈伤组织中的超倍体细胞频率。蔗糖浓度对最初9代愈伤组织染色体变异率无显著影响。但之后,低浓度蔗糖培养基上亚倍体细胞频率明显减小。随着培养时间的延长,各培养基上愈伤组织中正常二倍体细胞的频率都有逐渐上升的趋势。在再生植株中,大部分核型正常,只有少数植株具有染色体数目或结构变异。有些核型正常植株也有表型变异。     

Cytological investigations on two species of allocreadiid trematodes with special reference to the occurrence of triploidy and parthenogenesis in Allocreadium fasciatusi

Karyotypes and cytological details of gametogenesis were analysed for Allocreadium handiai and A. fasciatusi. Mitotic plates studied in squashes of testes, ovary, eggs and intramolluscan stages showed that A. handiai is a diploid (2n = 14) with six pairs of submetacentrics and one pair of subtelocentrics. Total chromosome length of the diploid complement was 86.57 μm, the largest chromosome measured 8.87 μm (10.24% total chromosome length [TCL]) and the smallest was 2.83 μm (3.28% TCL). Squashes of testes revealed the presence of all stages of spermatogenesis with spermatocytes in various stages of meiotic activity and spermatids containing bundles of spermatozoa. Stages of development of the ovum conclusively proved that reproduction takes place by amphimixis. Mitotic figures of A. fasciatusi, on the other hand, revealed that it is a triploid (3n = 21) with three metacentrics, 12 submetacentrics and six subtelocentrics. The mean total chromosome length of the triploid complement was 137.54 μm. The largest chromosome measured 10.37 μm (7.54% TCL) and the smallest measured 2.67 μm (1.94% TCL). Spermatogenesis was abortive with no evidence of synaptic pairing and spermatozoa were not produced. Eggs remained unfertilized and reproduction was achieved by parthenogenesis which is of mitotic type. The karyotypes of the two species differed not only in the ploidy level but also in the centromeric indexes of certain chromosomes.     

Characterization of nuclear and cytoplasmic information in the progeny of a somatic hybrid between male sterile Nicotiana tabacum and N. glutinosa

Summary Several nuclear and cytoplasmic characters of the back-crossed progeny of a somatic hybrid between male sterile Nicotiana tabacum (N. debneyi cytoplasm) and N. glutinosa have been analysed. Progeny were obtained by repeated back-crossing of a somatic hybrid with pollen from either N. tabacum or N. glutinosa. Nuclear ribosomal RNA genes (rDNA) were found to be a reliable marker to determine the constitution of nuclear genomes in the progeny. The progeny obtained by back-crossing with N. tabacum pollen maintained uniformity in leaf morphology. On the other hand, variation in leaf morphology was observed in the second back-cross population obtained with N. glutinosa pollen. This may be due to a variable contribution of N. tabacum chromosomes. Segregation of rDNA was also found in individuals of the same back-crossed progeny, but was not related to the chromosome number. The stable inheritance of chloroplast DNA in the back-crossed generation was confirmed regardless of the type of pollen donor. Male sterility was consistently maintained throughout several generations, suggesting that the nuclear genome of either N. tabacum or N. glutinosa does not influence the expression of cytoplasmic male sterility.     

Conservation of repetitive DNA sequences in deer species studied by Southern blot transfer

Summary The Cervidae show one of the largest variations in chromosome number found within a mammalian family. The five species of the deer family which are the subject of this study vary in chromosome number from 2n=70 to 2n=6. Digestion with the restriction enzymes EcoRI, HpaII, HaeIII and MspI reveals that there is a series of highly repetitive sequences forming similar band patterns in the different species. To obtain information on the degree of homology among these conserved sequences we isolated a HpaII restriction fragment of approximately 990 base pairs from reindeer DNA. This DNA sequence was³²P-labelled and hybridized by the Southern blot technique to DNAs cleaved with HpaII and HaeIII from the reindeer and four other Cervidae species. Hybridization to specific restriction fragments was recorded in all species. The patterns of hybridization showed a higher degree of similarity between reindeer, elk and roe deer than between reindeer and the Asiatic species (fallow deer and muntjac). Homologies are still present between the highly repetitive sequences of the five species despite the drastic reorganization that led to a change in chromosome number from 6 to 70.     

Chromosome number of Macraea Iaricifolia Hooker fil. (Compositae) and its bearhg on the taxonomic affinity of the genus

ELIASSON, U. H., 1984. Chromosome number of Macraea lariciflia Hooker fil. (Compositae) and its bearing on the taxonomic affinity of the genus. The chromosome number of Macraea laricifolia , a composite endemic to the Galápagos Islands, is reported to be 2 n = 28. Macraea was once regarded as congeneric with Lipochacta , a genus restricted to Hawaii. The chromosome number supports morphological evidence that the two genera arose independently from wedelioid ancestors within the Heliantheae.     

新制癌菌素和平阳霉素诱发蚕豆染色体畸变的比较研究

本文报道了新制癌菌素(NCS)能诱发植物染色体畸变,同时观察了利用咖啡因后处理对NCS、PYM诱发染色体畸变的影响,研究了PYM切断DNA断头的性质。结果表明,NCS切割DNA产生3'-羟基末端和3'-磷酸末端;咖啡因能封闭3'-羟基末端抑制DNA的修复,从而提高诱变频率。PYM加咖啡因后处理,其染色体畸变频率与PYM单独处理无明显差异。说明PYM切断DNA所得到的产物,不是3'-羟基末端,而是3'-磷酸末端。     

不同激素对伊贝母组织培养中染色体不稳定性的研究

伊贝母鳞茎培养在附加2,4—D、IAA、NAA和2,4—D+KT、IAA+KT、NAA+KT的MS培养基上(2,4—D、IAA、NAA1毫克/升,KT0.1毫克/升),研究了愈伤组织细胞染色体的变异及愈伤组织的分化和再生植株的染色体倍性。结果表明,2,4—D能有效地引起染色体数目的变化,当和KT结合使用时,可诱导高频率的多倍化细胞。IAA的作用次之,NAA较小。各种激素均能程度不同地引起各种类型的有丝分裂异常及染色体结构变异,其效应与对染色体数目变异的影响呈现明显的一致性。研究还得出,染色体的整倍性是愈伤组织得以分化的重要因素,所以再生植株主要是二倍体,也有少量的四倍体,混倍体仅占少数。根据实验结果,对染色体变异的原因以及染色体数目变异与愈伤组织分化的关系进行了讨论。     

Characterization of different types of condensed chromatin inCostus (Zingiberaceae)

The chromatin structure of six diploids species ofCostus was analysed using conventional Giemsa staining, C-banding and DAPI/CMA fluorochromes. The interphase nuclei in all the species show an areticulate structure and the prophase chromosomes show large blocks of proximal condensed chromatin. After banding procedures, each chromosome exhibits only centromeric dot-like DAPI⁺/CMA^– C-bands whereas the satellites (one pair at each karyotype) are weakly stained after C-banding and show a DAPI^–/CMA⁺ fluorescence. Two chromocentres show bright fluorescence with CMA and weak staining after C-banding whereas the others chromocentres show only a small fraction of DAPI⁺ heterochromatin. These results were interpreted to mean that the greater part of the condensed chromatin has an euchromatic nature whereas two types of well localized heterochromatin occur in a small proportion. The Z-stage analysis suggests that heterochromatin and condensed euchromatin decondense at different times. The chromosome number and morphology of all species are given and the implications of the condensed euchromatin are discussed.Dedicated to Prof.Elisabeth Tschermak-Woess on the occasion of her 70th birthday.     

Eyespot resistance gene Pch-1 from Aegilops ventricosa is associated with a different chromosome in wheat line H-93-70 than the resistance factor in “Roazon” wheat

Summary The hexaploid wheat line H-93-70 carries a gene (Pch-1) that has been transferred from the wild grass Aegilops ventricosa and confers a high degree of resistance to eyespot diesease, caused by the fungus Pseudocercosporella herpotrichoides. Crosses of the resistant line H-93-70 with the susceptible wheat Pané 247 and with a 7D/7Ag wheat/Agropyron substitution line were carried out and F2 kernels were obtained. The kernels were cut transversally and the halves carrying the embryos were used for the resistance test, while the distal halves were used for genetic typing. Biochemical markers were used to discriminate whether the transferred Pch-1 gene was located in chromosome 7D, as is the case for a resistance factor present in Roazon wheat. In the crosses involving Pané 247, resistance was not associated with the 7D locus Pln, which determines sterol ester pattern (dominant allele in H-93-70). In the crosses with the 7D/7Ag substitution line, resistance was neither associated with protein NGE-11 (7D marker), nor alternatively inherited with respect to protein C-7 (7Ag marker). It is concluded that gene Pch-1 represents a different locus and is not an allele of the resistance factor in Roazon wheat.