Root-Tip Smear Method for Difficult Material

A technic is outlined for the preparation of difficult material for the study of chromosome number and morphology in root-tip smears. The chief objective is to obtain polar views of the metaphase plates rather than equatorial views. To achieve this end it is recommended that fresh root-tips be cut free-hand into thin cross sections. The important features are: thin freehand cross sectioning of the fresh root-tips; fixing in Belling's iron aceto-carmine solution; maceration for 2-5 minutes in 50% HCl in 95% alcohol; and mounting in “Diaphane.”     

利用胚胎和幼孢子体进行蕨类细胞学研究

以蕨类植物胚胎和幼孢子体根为实验材料,以根尖和孢子母细胞为对照,进行细胞学观察方法的比较研究.结果显示:(1)野外材料的根尖仅在春季分裂期约1个月时间内存在分裂相,根尖个体数目较少(每植株根尖数目＜20条),根尖细胞内含有较坚硬的黏性物质,利用单株根尖进行压片,成功率低于40％;而从野外采回培养时根尖生长极为缓慢且较难成活,因而影响实验效果.(2)野外材料的孢子母细胞仅在孢子囊形成期约1周时间内存在分裂相,因此极大地限制了细胞学观察研究.(3)以胚胎和幼孢子体根为材料进行实验,单位面积(d=15cm培养皿)内幼孢子体根尖或胚胎的数量多于300个,分裂期细胞比例高,且细胞间基本不含黏性物质,进行细胞学研究时较少受到季节和实验时间的限制;利用单株根尖或胚胎进行压片,成功率高于80％.因此,利用蕨类植物的胚胎和幼孢子体根进行细胞学研究能有效地提高蕨类植物细胞学观察实验的成功率.     

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.     

Changes in mitochondrial activity during enlargement of mung bean root cells

A mitochondrial fraction was separately prepared from two differentregions of mung bean roots; from root-tips which contained mainlyimmature cells and from tissue, other than the root-tips, whichwas composed of mature and fully vacuolated cells. The malatedehydrogenase, fumarase and aconitase activities per cell didnot increase or did so only slightly during cell growth. Respiratoryactivity of both tissue sections and the crude mitochondrialfraction also seemed to increase slightly as cells matured.However, the cytochrome oxidase and succinate cytochrome c reductaseactivities per cell increased significantly during cell enlargement.There was no difference in the distribution-profiles of thecytochrome oxidase and malate dehydrogenase activities aftersucrose density gradient centrifugation, between mitochondrialfractions prepared from two regions of the. roots. The malatedehydrogenase activity per unit of cytochrome oxidase activityin purified mitochondria of immature cells was much higher thanthat of mature cells. The results suggest that enzymes in mitochondrialmatrix are mainly synthesized in immature cells or during celldivision. In contrast, enzymes in the cristae seem to be formedduring cell maturation, as well as being formed in immaturecells. (Received January 26, 1973; )     

Natural variation in nuclear characters of meristems in Vicia faba

The natural variation in chromosome size in root-tip and shoot apex meristems of Vicia faba has been studied. Chromosomes in main root-tips of one week old plants are 2–3 times larger than those in small lateral root-tips of 3 week old plants. While the nuclear DNA content remains constant, the nuclear RNA and nuclear histone contents show a positive linear correlation with chromosome volume. The DNA: histone ratio varies and is lowest in cells with large chromosomes. Nuclear volume and chromosome volume are not linearly related and changes in nuclear density therefore seem likely. A positive linear relationship between chromosome volume and mitotic index in colchicined squashes is demonstrated. The results strongly suggest that variation in chromosome size indicates a corresponding change in the rate of cell metabolism and may well reflect change in genetic activity.     

化学药剂诱导玉米孤雌生殖植株的细胞遗传学研究

对化学药剂诱导玉米孤雌生殖获得的植株的染色体组成及其稳定性进行了研究。试验用2％二甲基亚砜(DMSO)+0.1％秋水仙碱;40％ppm马来酰胼(MH)+0.1％秋水仙碱;40ppm MH+2％ DMSO三种处理,共获得130粒孤雌生殖种子。本文对孤雌生殖种子的植株及后代进行了细胞遗传学分析、讨论。试验分析了145株孤雌生殖植株和对照植株的根尖细胞,和其中的88株的花粉母细胞。有半数以上植株的根尖细胞为混倍体,但除1株外,其余的混倍体植株的花粉母细胞均为二倍体。这一异常植株的花粉母细胞仍为混倍体,其子代中有二倍体和各种非整倍体植株。这一结果表明,用这种方法不仅能获得二倍体纯系,而且还可以获得非整倍体。     

The effects of methyl methanesulphonate on mitosis and chromosomes of excised barley embryos

Excised barley embryos were treated with methyl methanesulphonate and cultivatedin vitro in water or in a nutrient medium. The alkylating compound induced a high frequency of chromosome aberrations observed at anaphase and metaphase and depressed the mitotic division in the root-tips of excised embryos.     

崇明水仙根尖体细胞染色体的观察和核型分析

以崇明水仙(Narcissus tazetta L.var.chinensis Roem.)根尖体细胞为实验材料,对适宜于崇明水仙细胞学研究的前处理液和前处理时间进行了筛选,在此基础上,应用根尖压片法对重瓣花型和单瓣花型崇明水仙体细胞染色体数、核型及倍性进行了比较分析.结果显示:适宜的前处理液是对二氯苯饱和溶液,适宜的前处理时间为12 h.重瓣花型和单瓣花型崇明水仙的染色体核型差异较小,相同点为:不对称二型核型,染色体基数x=10,三倍体,体细胞染色体数2n=3x=30,第7号染色体的短臂具随体,核型均属于"3B"型,臂比大于2的染色体比率为90%.不同点为:重瓣花型的第7号和第8号染色体分别为sm和st型,单瓣花型的第7号和第8号染色体分别为st和sm型;前者的核型不对称系数(76.48%)略小于后者(76.71%);前者的相对长度系数为12L+6M2+12S,后者的相对长度系数为12L+3M1+3M2+12S;前者的最长染色体与最短染色体长度的比值(3.10)略小于后者(3.19).重瓣花型的核型公式为2n=3x=30=15st+15sm(3SAT),单瓣花型的核型公式为2n=3x=30=15st(3SAT)+15sm,崇明水仙根尖体细胞染色体的平均核型公式为2n=3x=30=15st(3SAT)+15sm.根据研究结果初步推测崇明水仙为节段异源三倍体.     

Cryopreservation and post freeze molecular and biosynthetic stability in transformed roots of Beta vulgaris and Nicotiana rustica

Crypopreservation methods were firstly developed for root-tips from hairy root cultures of Beta vulgaris, established after transformation by Agrobacterium rhizogenes. The effects of culture age, pre-growth, cryoprotection, freezing rate and post-freeze culture conditions were determined. The resulting freezing protocol was then used to cryopreserve transformed root cultures of Nicotiana rustica. Both species were viable after freezing (ca. 80%), according to fluorescein diacetate vital staining. However, on average the regeneration of proliferating roots from surviving root-tips was low (<20%). Growth rates, secondary metabolite production and T-DNA structure of a number of hairy root lines were examined and found to be unchanged after cryopreservation.Abbreviations DMSO dimethyl sulphoxide - 2,4-D dichlorophenoxyacetic acid - FDA fluoroscein diacetate - IAA indole-3-acetic acid - NAA -napthalene acetic acid     

A Schedule for the Study of Somatic Chromosomes in Bromus

Clean healthy roots are obtained by excising a few tillers very close to their point of emergence from the base of a larger plant and then growing them in vermiculite to which is periodically added a quantity of a complete mineral nutrient solution, sufficient to keep the medium moist. The roots are treated, while still intact on the living plant, with 0.0015 M 8-hydroxyquinoline for 4 hours at 18°C. At the end of treatment, the roots are excised and placed in 45% acetic acid for approximately 5 minutes, after which the root-tips are stained in Feulgen. Thereafter, temporary squash preparations are made of the meristems.     

The Use of Sodium Diethyldithiocarbamate as a Respiratory Inhibitor

A technique for the application of dieca (diethyldithiocarbamate)to plant tissues is described. It is shown to differentiatealmost quantitatively between extracted ascorbic oxidase andpolyphenolase on the one hand and cytochrome oxidase on theother at a concentration of M/5,000. It produces strong, butnot total, inhibitions when applied to barley root-tips.     

六种贵州淫羊藿属植物的核型分析

用压片法对原产贵州的六种淫羊藿属植物的根尖有丝分裂中期染色体核型进行了比较研究。结果表明:这6种淫羊藿在核型上基本相同,都有1对中间随体染色体,而且都为对称核型。箭叶淫羊藿、粗毛淫羊藿、巫山淫羊藿、黔北淫羊藿、四川淫羊藿的核型公式均为6m(2SAT)+6sm,而黔岭淫羊藿的为8m(2SAT)+4sm。     

禺毛茛及其复合体种间亲缘关系形成研究

在Tamura M.,Okada及廖亮研究的基础上,通过禺毛茛复合体(禺毛茛R.cantoniensis 4x,卷喙毛茛R.sileri folius var.silerifolius 2x,长花毛茛R.sileri folius var.dolicathus 2x,茴茴蒜R.chinensis 2x,扬子毛茛R.sieboldii 6x及8x)的核型分析,结合地球环境的演变历史,进一步研究了禺毛茛的形成方式和时间,并对禺毛茛复合体种间亲缘关系的形成进行了探讨,为毛茛属系统进化研究提供资料。     

Effects of explants and growth regulators in garlic callus formation and plant regeneration

We intended to evaluate the effects of different explants and growth regulators on callus induction and plant regeneration in garlic (Allium sativum L.). Furthermore, we intended to differentiate among different morphological types of callus by light microscopy and to relate them with their abilities to regenerate plants in the red-garlic cultivar 069. A factorial design with BDS—basal Dunstan and Short (1977)—medium, as a control and supplemented with 0.042, 0.42 and 4.24 μM picloram or with 0.045, 0.45 and 4.5 μM 2,4-D, in both cases with and without 4.43 μM N⁶-benzylaminopurine (BAP), was used. The cultures were grown in darkness at 25 ± 2°C and they were subcultured over a 6-month period. Basal plates and meristems were highly responsive explants, while immature umbels and root-tips were less responsive ones, as indicated by percentage of induced callus, growing callus and regenerating callus. The best response was 41% regenerating callus with 0.045 μM 2,4-D and BAP from basal plates while 57, 56 and 20% regenerating callus were obtained with 0.45 μM 2,4-D from meristems, root-tips and immature umbels, respectively. Also, these treatments showed a higher percentage of nodular and embryogenic callus (type I). Thus, it can be concluded that the use of meristems and 2,4-D will enhance callus production and quality, increase plant regeneration and allows to develop a protocol suitable for further transformation experiments in garlic.     

Uptake and Incorporation of 14C-labelled Maleic Hydrazide into the Roots of Salix viminalis

Labelled maleic hydrazide (MH) was shown to be accumulated preferentially into the root-tips of young Willow roots by radiochemical analysis. A large proportion of the activity incorporated into the cell constituents was associated with RNA. MH was also bound in some way to the cell wall material. The greatest proportion of the activity was easily removed from the root tissue and thus probably occurred free within the cytoplasm and free-space. The incorporation of MH into RNA and its subsequent effects on cell metabolism via abnormal protein and enzyme synthesis is given as an explanation of the mode of action of MH.     

The Use of Snail Gut Cytase in Fluorescent Banding Studies on Plant Chromosomes

The fluorescent bands produced in chromosomes by quinacrine derivatives, although highly acid-labile, have been shown to be resistant to digestion by snail gut cytase. This enzyme may therefore be used to soften plant root-tips and so facilitate the production of flat, unbroken mitotic-metaphase plates for fluorescent-banding studies. The roots are fixed in 3:1 absolute alcohol:glacial acetic acid then thoroughly washed in water. The washed roots are then dipped in undiluted cytase and digested for either 2 hrs at room temperature or overnight in a domestic refrigerator. Next they are squashed on a slide and stained in 0.5% aqueous quinacrine hydrochloride for 10-15 minutes at pH 6.2. After washing in three changes of water they are mounted in water. The coverslips are sealed on with clear nail varnish.     

Snail Stomach Cytase, A New Reagent for Plant Cytology

A very active mixture of cytase and other enzymes is present in the stomach fluid of Helix pomatia, the edible snail. This fluid makes an ideal macerating medium for squash preparations of root-tips and other similar plant tissues. The complete separation of all cells is easily achieved, while the chromosomes remain completely unaffected. The method of using this fluid is described; it can be applied in conjunction with any of the standard     

Studies on the Physiology of Nodule Formation: III. Experiments on the Excision of Root-tips and Nodules

The excision of nodules and root-tips from red clover inoculatedwith an effective strain of nodule bacteria leads to an increasein the number of nodules subsequently formed. This is thoughtto be due to the removal by excision of the source of an inhibitor.In the nodule the inhibitory activity appears to be centredin the growing-point and not in the bacterial tissue, sincethe excision of the nodular meristem only will stimulate furthernodulation. The response to excision depends upon the numberof excisions made and is inversely related to the inherent susceptibilityof the individual plant. Excision of nodules from plants inoculated with ineffectivestrains of bacteria has no influence on further nodulation,presumably because the growing-points of the nodules are abortive.     

Cell division and cell growth in size

Summary and conclusion The coefficient of correlation between cell length and percentage mitosis in root-tips ofZea mays was found to be high and negative: r=–0·577±0·075. This value taken together with correlated data justifies the generality that cell division and cell size are inversely related. An analysis of the bases of the relation brings the conclusion that in an increasing cell population where growth in cell number and growth in cell size are taking place simultaneously, cell division is the independent and cell size the dependent variable. That is to say, other things being equal, the size of the cells is a result of the rate of cell multiplication. The explanation of this is given in the text.     

淫羊藿属十二个种的核型

用细胞压片法对12 个淫羊藿属( Epimedium) 植物的根尖有丝分裂进行了观察, 并对其核型进行了比较研究。结果表明: 这12 种淫羊藿在核型上基本相似, 都有1 对中间随体染色体, 而且都为对称核型。粗毛淫羊藿( E. acuminatum) 、印江淫羊藿( E . yinjiangense )、单叶淫羊藿( E. simplicifloum) 、巫山淫羊藿( E. wushanense) 、光叶淫羊藿( E. myrianthum) 、宝兴淫羊藿( E. davidi) 、罗甸淫羊藿( E. luodianense) 、木鱼坪淫羊藿( E. franchetii ) 、箭叶淫羊藿( E. sagittatum) 、E. pubigerum、高山淫羊藿( E. alpinum) 等11 个种的核型公式均为2n = 2x= 6m (2SAT ) + 6sm, 而黔岭淫羊藿( E. leptorrhizum) 的核型公式为2n = 2x = 8m ( 2SAT ) + 4sm。结果显示12 种淫羊藿的体细胞染色体数目均为2n = 12 , 基数X = 6; 都属于对称核型、都有1 对中间随体; 染色体均为m、sm 两种类型。