Establishment and characterization of photoautotrophic protoplast-derived cultures ofNicotiana plumbaginifolia

A procedure is described for the rapid establishment of photoautotrophic protoplast-derived cultures ofNicotiana plumbaginifolia. Photoautotrophic growth was induced by lowering the glucose concentration to 2.5 g.l^–1 in the protoplast culture medium and by omitting glucose from the subsequent dilution medium. Four week-old highly viable suspensions were plated on an agar-medium without glucose in unsealed Petri dishes and kept in illuminated chambers flushed with 0.05 % or 2 % CO₂. Air-grown calli had net photosynthesis rates of 1.8 and 17 moles CO₂.g^–1 fresh wt.h^–1 in air at 0.034 % CO₂ and in air enriched with 1 % CO₂, respectively. Calli grown in 2 % CO₂ exhibited lower rates of net photosynthesis at the two CO₂ concentrations tested (0 and 7.5 moles CO₂.g^–1 fresh wt.h^–1, respectively). The contribution of photosynthesis to growth was estimated to be 80 % in air-grown calli and more than 90 % in calli grown in 2 % CO₂. The suitability of this photoautotrophic culture procedure is discussed with regard to the screening of photosynthetic mutants or transformants from protoplasts.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzylaminopurine - IAA indoleacetic acid - Rubisco ribulose 1,5-bisphosphate carboxylase/oxygenase     

中国二种癞蝗染色体C带核型

染色体C带核型在物种鉴定、分类阶元间的比较及其系统演化关系的推断中是一个有用的指标,染色体组内C带分布位置、大小、数量及异染色质含量可以反映出属、种及种下阶元的细胞学异同。文章报道中国2种癞蝗——红缘疙蝗Pseudotmethis rubimarginis Li和准噶尔贝蝗Beybienkia songorica Tzyplenkov的染色体C带核型,结果表明:2种癞蝗均为XO(♂)型性别决定机制。染色体组成均为2n♂=19,染色体为端着丝粒染色体;在各染色体相对长度,C带的大小,位置和着色程度上又存在不同程度的差异,可以作为区分种的依据。     

Isolation and characterization of microprotoplasts from APM-treated suspension cells ofNicotiana plumbaginifolia

Summary Subprotoplasts with a DNA content of less than the G1 level (microprotoplasts) were isolated from micronucleated cells of transformedNicotiana plumbaginifolia (Doba line resistant to kanamycin) and characterized cytologically as well as by flow cytometry and Feulgen microdensitometry. Micronuclei were induced upon treatment of the suspension cells with the anti-microtubule drug amiprophos-methyl (APM). Protoplasts were fractionated on a continuous iso-osmotic gradient of Percoll; this resulted in several visible bands. Flow cytometric analysis of fluorescein and nuclear DNA contents after staining with fluorescein and DAPI respectively showed that the main band contained mostly evacuolated, intact (sub)protoplasts. Microprotoplasts contained one or a few micronuclei surrounded by a thin rim of cytoplasm and an intact plasma membrane. A maximum of 40% of the microprotoplasts in the fraction just below the main band had a DNA content less than the G1 level, in other fractions this maximum was 20%. Some of these contained an amount equivalent to that of one or a few chromosomes. The application of microprotoplasts for chromosome-mediated gene transfer in plants is indicated.     

Regeneration of plants from mesophyll protoplasts ofNicotiana plumbaginifolia Viv.

Summary Protoplasts ofNicotiana plumbaginifolia were isolated by a one step enzymatic method. They were cultured in Ohyama and Nitsch's medium supplemented with 2,4-D (1.0 mg/l), benzylaminopurine (1.0 mg/l) and 14% sucrose. Cell divisions were initiated after 5 days and within 3 weeks colonies were discernible without the microscope. After transfer to Murashige and Skoog's medium containing IAA and kinetin the colonies differentiated into plantlets.     

Nuclear behaviour of colonies and regenerated buds from protoplasts ofNicotiana plumbaginifolia Viviani haploids

The ploidy level variations of protoplast cultures ofNicotiana plumbaginifolla Viviani (n=10) were investigated from protoplast isolation until regenerated buds, using cytophotometric measurements of nuclear DNA content and chromosome counting. An increase in the average nuclear DNA amount has been found to occur in freshly isolated protoplasts after 15 hours of maceration. Cytological abnormalities like nuclear fragmentation, chromatin connections between interphasic nuclei and micronuclei were observed during the following days. Chromosome counting in 15, 30 and 50-day-old calli and in regenerated buds revealed that nuclei are haploid, diploid or aneuploid.Abbreviations p-cells, p-calli or p-colonies protoplast-derived cells, calli or colonies - BAP 6-benzylaminopurine - NAA 1-naphtaleneacetic acid - 2iP ²-isopentyl-aednine     

新疆裸重唇鱼染色体的核型及C-带研究初报

探索新疆裸重唇鱼的染色体数目和核型,并对新疆裸重唇鱼染色体进行C带型的描述和分析,填补领域内对这一物种研究的空白,为后续的研究打下基础。采用PHA体内注射肾细胞直接制片法研究新疆裸重唇鱼的核型,采用改进的BSG法来研究其C-带。结果表明,新疆裸重唇鱼的核型公式为2n=98=28m＋30sm＋12st＋28t,臂数NF=156。m1、sm1、sm2、t1和t2明显比同组其他染色体大,未发现小染色体及其他异型性染色体。C-带较丰富显示出3种类型的C-带,所有染色体都有着丝粒带,部分有端粒带,有些染色体两端都有端粒带,有些只有一端有端粒带,sm5、sm12和t 3还显示深浅不一的居间带。并通过与同亚科种类进行对比分析,讨论它们的亲缘关系和系统演化。     

Dark requirement for cell regeneration and colony formation by mesophyll protoplasts ofNicotiana plumbaginifolia Viv.

Summary The protoplasts ofNicotiana plumbaginifolia required darkness for cell regeneration and colony formation. Maximal plating efficiency of the protoplasts could be achieved by keeping the cultures in dark instead of light or dark/light sequence. Only two days of darkness prior to the illumination at 400 or 3,000 lux resulted in appreciable plating efficiency, than those of light from the beginning, but these values could not match the high plating efficiency in total darkness.     

The G- and C-banding karyotype of the Arabian oryx (Oryx leucoryx)

The chromosomes of the Arabian oryx (Oryx leucoryx) were investigated using GTG and CBG banding technique. Their banding patterns were compared to those of goat and cattle.     

A comparison of the effects of various spindle toxins on metaphase arrest and formation of micronuclei in cell-suspension cultures ofNicotiana plumbaginifolia

The effects of the spindle toxins colchicine, oryzalin and amiprophos-methyl (APM) on metaphase arrest, chromosome scattering, and on the induction and yield of micronuclei were compared in suspension cells ofNicotiana plumbaginifolia (kanamycin-resistant “Doba” line). The inhibition of spindle formation is stronger with oryzalin and APM than with colchicine, which resulted in a more efficient accumulation of meta-phases with well-scattered chromosomes, allowing the isolation of single chromosomes. Further, APM and oryzalin treatments resulted in a higher frequency of micro-nucleated cells and greater yield of micronuclei than after colchicine treatment. The different actions of the chemicals on the functioning of the spindle, development of nuclear membranes around the chromosomes, formation of micronuclei and fusion of micronuclei, resulting in restitution nuclei, are discussed.     

C-banding karyotype and relationship of the dipodids Allactaga and Jaculus (Mammalia: Rodentia) in Egypt

The C-banding karyotype of the jerboas Allactaga tetradactyla, Jaculus jaculus jaculus, and Jaculus orientalis was described and interspecific relationships were discussed. Despite the conservation of a relatively small amount of C-heterochromatin located at the centromeric region of some chromosomes in all karyotypes, a striking loss of C-heterochromatin was clearly observed in J. orientalis. C-bands were totally absent in 33 of the 48 chromosomes of J. orientalis, compared to only 7 for J.j.jaculus and 11 for A. tetradactyla. The differences in C-banding amongst karyotypes of the three species were attributed either to transformation of heterochromatin into euchromatin or vice versa, deletion of heterochromatic segments resulting from pericentric inversions, or to variation of euchromatin content and its correlation with the chromosome size and arrangement of heterochromatin. The present findings are consistent with the main hypotheses derived from morphological, chromosomal, and biochemical data that the genera Allactaga and Jaculus have independently developed from a common ancestral form and that J. jaculus and J. orientalis are both distinct congeneric species, but revealed that the C-banding karyotypes of both J.j.jaculus and J. orientalis are distantly related to each other. Therefore, it is concluded that the karyotype of J.j.jaculus may be ancestral and that of J. orientalis may have derived from it.     

Analysis of the human karyotype using a reassociation technique

A characteristic banding pattern can be made visible in human chromosomes by a denaturating and renaturating procedure performed on cytological preparations. The banding pattern is characteristic of each chromosome pair, allowing easy identification of all human chromosomes. The method is likely to provide a useful tool in the identification of mammalian chromosomes and in the study of aberrations and variations in the chromosome set.     

C-banding pattern and meiotic pairing in five rye chromosomes of hexaploid triticale

Summary The meiotic behaviour of rye chromosomes 1R, 2R, 3R, 6R and 7R/4R of hexaploid triticale Cachirulo is analyzed using the C-banding technique. These chromosomes show different C-banding patterns and present different pairing levels at metaphase I. A decreasing effect of large telomeric heterochromatin bands on pairing is deduced from the following two main facts: i) The chromosome 7R/4R shows the highest pairing associated with the smallest amount of heterochromatin, ii) pairing levels of 2 R short arm and 3 R long arm which carry large telomeric bands are less than their respective long and short arms lacking telomeric heterochromatin. Possible desynaptic effects of heterochromatin are discussed although an asynaptic effect cannot be rejected.     

Comparison of the chromosomes of Triticum timopheevi with related wheats using the techniques of C-banding and in situ hybridization

Summary The chromosomes of the tetraploid wheats Triticum timopheevi (Genome AAGG) and T. araraticum (Genome AAGG) were C-banded at mitosis. The identity of the banded and unbanded chromosomes was then established by firstly making comparisons with the hexaploid species T. zhukovskyi which has the genome formula AAAAGG. Secondly, the meiotic pairing in F₁ hybrids between T. timopheevi and diploid wheats was examined by means of C-banding. The results showed that the banded chromosomes belonged to the G genome, while the unbanded chromosomes belonged to the A genome. Only one of the two pairs of satellited chromosomes had strong heterochromatic bands. The relationship between the genomes of T. timopheevi and T. dicoccum (Genome AABB) was then assessed at meiosis in hybrids between these species, using the techniques of C-banding and in situ hybridisation of a cloned ribosomal RNA gene probe. It was concluded that there were differences both in the amount and distribution of heterochromatin and also translocation differences between the species.     

An auxin-resistant mutant ofNicotiana plumbaginifolia Viv. is impaired in 1-naphthaleneacetic acid-induced hyperpolarization of hypocotyl cell membranes in intact seedlings

The electrical response to the synthetic auxin 1-naphthaleneacetic acid (1-NAA) ofNicotiana plumbaginifolia wild type and the monogenic, dominant auxinresistant mutant R25 was studied. Membrane potentials were continuously recorded in hypocotyl cells of light-grown, intact seedlings, and the time course of the response to 1-NAA addition was followed. Wild-type cells responded to ? 10^?5 M 1-NAA with a delayed, transient hyperpolarization. The R25 cells hyperpolarized significantly only in response to 1-NAA at 10^?3 M, and with maximal amplitudes lower than those recorded with the wild type. In contrast, the two genotypes reacted similarly in terms of kinetics and amplitude to 10^?5 M fusicoccin, which rapidly and strongly hyperpolarized the cells, and to 10^?3 M benzoic acid, which induced rapid and weak hyperpolarization. The resting membrane potentials of the wild type and R25 were also not significantly different. Unlike wild-type hypocotyls, those of R25 ceased elongating before the time chosen for the electrophysiological measurements, but control experiments performed at a time when the elongation of both genotypes had terminated indicated that the difference in electrical response to auxin is independent of hypocotyl growth. The inefficiency of 1-NAA in inducing hyperpolarization of R25 hypocotyl cells suggests a defect at an early step in auxin action.     

Identification of the pattern of heterochromatin distribution in Passiflora species with C-banding

We tested four C-banding protocols to obtain heterochromatic bands in the passion fruit species Passiflora edulis and P. cacaoensis (Passifloraceae). Three of these protocols had been previously described. The three published protocols were not adequate to obtain C-bands in these species. An adapted protocol demonstrated heterochromatin distribution in metaphasic chromosomes of species of Passiflora for the first time. The differentiated coloration for C-bands was obtained with immersion of the slides in 99% ethanol, 45% acetic acid (additional step), 0.2 N hydrochloric acid, hydroxide of barium, 45% acetic acid, and 2X standard saline citrate at four different temperatures. The C-bands were observed in the satellites and in the telomere and centromere regions of all chromosomes, both in P. edulis and in P. cacaoensis.     

向日葵染色体Giemsa C-分带研究

采用HKG (HCI-KOH-Giemsa)法对内葵杂3号三交种染色体进行了C-分带研究和分析.结果表明:每条染色体至少都有一条C-分带,染色体组共有62务C-分带,以中间带和着丝点带为主,中间带主要分布在染色体短臂上;C-分带强弱差异明显,其中46条强带,16条弱带.Giemsa C-分带带型公式为:2n =2x =34 =8I++3T++5I+I+T++4C +2CI+4CI+ +3CI+ +I+T++CT++2CT+.每条染色体都显示出显著的带纹特征,因此,利用Giemsa C-分带方法可以将向日葵的每条染色体区分开.     

The Giemsa banding pattern of the canine karyotype.

The canine metaphase karyotype consists of 78 chromosomes. All autosomes exhibit telocentric or acrocentric configurations gradually diminishing in size. These features make identification of homologous pairs by conventional analysis difficult. Chromosome preparations were derived from short-term cultures of peripheral blood lymphocytes obtained from clinically normal dogs representing at least four breeds. Most components of the canine karyotype can be distinguished readily. No significant G-banding pattern variations were detected in the individuals screened. An idiogrammatic interpretation of the banding pattern is presented. Apart from bands, other characteristic morphologic features were found which aid in identification. The G-banding pattern of the canine metacentric X is quite similar to that of the banded human X. The canine Y is a minute metacentric having two positive bands.