scholarly journals AFFINITY DISTANCE VALUES AMONG SOMATIC METAPHASE CHROMOSOMES IN MAIZE

Genetics ◽  
1978 ◽  
Vol 88 (1) ◽  
pp. 181-199
Author(s):  
J D Horn ◽  
D B Walden
Keyword(s):  
Random Distribution ◽  
Maize Root ◽  
Root Tip ◽  
Metaphase Arrest ◽  
Metaphase Chromosomes ◽  
Somatic Metaphase ◽  
Chemical Agents ◽  
Differential Responses

ABSTRACT In maize root-tip metaphase preparations, all distances between two chromosomes were measured in 50 cells from each of seven stocks and in 30 from one stock; four were arrested with cold, two with 8-hydroxyquinoline, one with colchicine and one with monobromonaphthalene Standardized, affinity-distance values were calculated for all pairs of homologues and pairs of nonhomologues from each preparation. The homologues of pair X were the least separated, those of pair I the most separated in the cold-arrested stocks. All but pairs I and VIII were shown to be significantly different from the observed mean. The observed mean was less than but not significantly different from the theoretical value for a random distribution. The use of chemical agents for metaphase arrest increased the separation of homologues, except for pair I.—Eleven percent of the comparisons of nonhomologues from cold-arrested, as contrasted to none of the comparisons from the c-metaphase treatments, were significantly different from the theoretical talue for a random distribution. This was considered evidence for limited primary nonhomologue association in maize. Although there were specific, differential responses to the two arrest agents, the population of homologous pairs approached a random distribution only in chemically arrested stocks.—Primary homologue association was considered to be maintained by two mechanisms. the more common involving the micro-tubules and the second involving the nucleolus.—Interpretations are offered regarding the claims of somatic association in other species, especially man. The opportunity in maize for experimentally modifying distance values by cytogenetic techniques is discussed.

Cell synchronization and isolation of metaphase chromosomes from maize (Zea mays L.) root tips for flow cytometric analysis and sorting

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 697-703 ◽  
Author(s):  
Jai-Heon Lee ◽  
K. Arumuganathan ◽  
S. M. Kaeppler ◽  
C. M. Papa ◽  
H. F. Kaeppler
Keyword(s):  
Cell Cycle ◽  
Flow Cytometric Analysis ◽  
Maize Root ◽  
Root Tip ◽  
Root Tips ◽  
Chromosome Sorting ◽  
Synthesis Inhibitor ◽  
Metaphase Chromosomes ◽  
Flow Karyotype ◽  
Flow Cytometric

Accumulation of cells containing metaphase chromosomes is an important step in cytological analyses and chromosome sorting procedures. The goal of this research was to optimize treatment parameters to synchronize the cell cycle of maize root tip meristem cells. Levels of hydroxyurea, a DNA synthesis inhibitor, were assessed for their utility in accumulating cells at the G1 phase of the cell cycle. Trifluralin, amiprophos-methyl, and colchicine were used to accumulate cells containing metaphase chromosomes upon release from hydroxyurea inhibition. Optimal mitotic indices were achieved by treating seedlings with 5 mM hydroxyurea for 18 h, incubating for 1 h without chemical treatment to release the hydroxyurea block, and then treating emerging roots with 1 μM trifluralin for 4 h. The mitotic index of synchronized maize root tips was over 70%. Uniformity of synchronization depended upon selection of seeds with emerging radicles that were similar in length at the time of treatment. Suspensions of intact chromosomes were prepared by a simple slicing procedure. The chromosome preparations were found to be suitable for flow cytometric characterization and sorting. Chromosome peaks of the observed flow karyotype resembled the predicted flow karyotype calculated on the basis of maize chromosome size. Key words : flow karyotype, hydroxyurea, plant chromosome sorting, trifluralin.

Growth of the maize root tip

1950 ◽  
Author(s):  
Gabriel Baldovinos de la Pena
Keyword(s):  
Maize Root ◽  
Root Tip

scholarly journals The epidermal surface of the maize root tip. I. Development in normal roots

1993 ◽  
Vol 125 (2) ◽  
pp. 413-429 ◽  
Author(s):  
R. M. ABEYSEKERA ◽  
M. E. McCULLY
Keyword(s):  
Maize Root ◽  
Root Tip ◽  
Epidermal Surface

scholarly journals STUDIES ON THE ISOLATION OF METAPHASE CHROMOSOMES

1963 ◽  
Vol 19 (1) ◽  
pp. 59-69 ◽  
Author(s):  
M. Choraży ◽  
A. Bendich ◽  
E. Borenfreund ◽  
D. J. Hutchison
Keyword(s):  
Leukemia Cells ◽  
Hypotonic Solution ◽  
L1210 Leukemia ◽  
Metaphase Chromosomes ◽  
Morphological Alterations ◽  
Chemical Agents ◽  
Morphological Criteria

A method for the isolation of metaphase chromosomes from mouse L1210 leukemia cells has been developed. Cells, arrested at metaphase with colchicine, were exposed to hypotonic solution and the pH was then adjusted to 5.6 to stabilize the chromosomes. The metaphase figures were subsequently disrupted and the chromosomes isolated by a series of differential centrifugations in sucrose. The isolated chromosomes were well preserved, as judged by morphological criteria. The effect of various enzymes and chemical agents on the isolated chromosomes was studied. Chymotrypsin, trypsin, and deoxyribonuclease caused a marked disintegration of the chromosomes, whereas treatment with pepsin and ribonuclease induced no significant morphological alterations.

In situ localization of two repetitive DNA sequences to surface-spread pachytene chromosomes of rye

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 551-559 ◽  
Author(s):  
S. M. Albini ◽  
T. Schwarzacher
Keyword(s):  
In Situ Hybridization ◽  
Synaptonemal Complex ◽  
Dna Sequences ◽  
Meiotic Prophase ◽  
Hybridization Signal ◽  
Metaphase Chromosomes ◽  
Somatic Metaphase ◽  
Rdna Signal ◽  
Surface Spread

Surface-spread pollen mother cells at meiotic prophase from Secale cereale (rye) were used for fluorescent DNA:DNA in situ localization of two tandemly repeated DNA sequences: pTa71, a wheat rDNA clone, and pSc119.2, a cloned 120-bp repeat from rye heterochromatin. The fluorescent hybridization signal, consisting of many yellow-green dots, was closely associated with the bivalent axes, corresponding to the synaptonemal complex, and located in the surrounding chromatin. The rDNA signal was associated with one bivalent, the smallest of the seven, at a distance about 13% of the bivalent length from the telomere. This corresponded to the position of the nucleolar organizing region of silver-stained synaptonemal complexes analyzed under the electron microscope and published data for somatic metaphase chromosomes. The relative length of the axis covered with the rDNA signal is less than expected from somatic metaphases, but it corresponds more closely to the proportion of the sequences in the genome. The hybridization signal with the 120-bp repeat was located mainly at the telomeric regions of several bivalents that showed thickenings of the axis after DAPI staining, probably corresponding to somatic C-bands. These major and some minor intercalary sites agree with the distribution of the 120-bp repeat in somatic metaphase. Fluorescent in situ hybridization to plant surface-spread pachytene chromosomes, which can be obtained in large numbers, has great potential for studying meiotic prophase, high-resolution mapping of DNA sequences, and investigating the relationship of DNA sequences to the synaptonemal complex.Key words: in situ hybridization, cereals, pachytene, meiosis, synaptonemal complex, physical mapping.

DISTRIBUTION OF HETEROCHROMATIN IN THE CHROMOSOMES OF HAPLOPAPPUS GRACILIS

1968 ◽  
Vol 10 (2) ◽  
pp. 433-443 ◽  
Author(s):  
Ira H. Ames ◽  
Jyotirmay Mitra
Keyword(s):  
Aqueous Solution ◽  
Chromosome Aberrations ◽  
Maleic Hydrazide ◽  
Cold Treatment ◽  
The Other ◽  
Root Tip ◽  
Metaphase Chromosomes ◽  
Haplopappus Gracilis ◽  
Tip Cells ◽  
Root Tip Cells

Several approaches were employed to study the distribution of heterochromatin in root tip chromosomes of Haplopappus gracilis. Cold treatment and pretreatment in an aqueous solution of 8-hydroxyquinoline revealed achromatic gaps in metaphase chromosomes. Cold treatment also permitted the demonstration of positive heteropycnosis in prophase chromosomes. Further support for the identification of heterochromatic segments was provided by a study of the localization of chromosome aberrations induced by maleic hydrazide and an analysis of the pattern of DNA synthesis in chromosomes of root tip cells. Seven of the ten regions that were preferentially broken by maleic hydrazide also reacted differentially to cold treatment or to pretreatment with 8-hydroxyquinoline. A good correlation was found between regions that completed DNA replication late in the DNA-synnhetic period and segments that were shown to be heterochromatic by the other techniques.

Sign in / Sign up

Export Citation Format

Share Document