CHROMOSOME STABILITY IN MAIZE (ZEA MAYS) TISSUE CULTURES AND SECTORING IN SOME REGENERATED PLANTS

1982 ◽  
Vol 24 (5) ◽  
pp. 559-565 ◽  
Author(s):  
T. J. McCoy ◽  
R. L. Phillips
Keyword(s):  
Zea Mays ◽  
Cultured Cells ◽  
Chromosome Complement ◽  
Recessive Mutation ◽  
Chromosome Stability ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Recessive Mutations ◽  
Regenerated Plants

Cytogenetic stability of maize (Zea mays L.) tissue cultures was assessed by meiotic analysis of plants regenerated from 4- and 8-month-old tissue cultures and by mitotic analysis of cultured cells 4 and 8 months after culture initiation. Cultures initiated from four embryos each of W22 R-nj R-nj × A188 and A188 × W22 R-nj R-nj were examined. After four months in culture, only one of 65 regenerated plants was abnormal; after eight months, only four of 59 regenerated plants were abnormal. Three of the five abnormal plants had normal and cytogenetically abnormal sectors in the tassels. Inheritance studies were conducted on 51 regenerated plants. Eight plants segregated in the S1 for recessive mutations resulting in defective kernels, and one plant segregated for a recessive mutation resulting in a wilted phenotype. Eight different plants that produced normal S1 progeny segregated for defective kernel mutations in some S1 families, indicating a lack of concordance between male and female reproductive cells in the original regenerated plant. The cytogenetic stability observed in regenerated plants also was observed in vitro, indicating that selection at the time of regeneration did not occur. Four hundred and thirty-four (97%) of the 449 cells analyzed in 4-month-old cultures had the normal 20-chromosome complement; 377 (95%) of the 398 cells analyzed in 8-month-old cultures were normal. These results indicate that chromosome stability is maintained in tissue cultures of A188 × W22 R-nj R-nj maize.

Genomic rearrangements in maize induced by tissue culture

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 122-128 ◽  
Author(s):  
Michael Lee ◽  
R. L. Phillips
Keyword(s):  
Tissue Culture ◽  
Zea Mays ◽  
Zea Mays L ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Callus Cultures ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Regenerated Plants

Chromosomal instability is a common occurrence in plant tissue cultures and has been documented in plants regenerated from several genotypes of maize (Zea mays L.) tissue cultures. The objective of this research was to evaluate the frequency and types of chromosomal aberrations in regenerated plants of an Oh43–A188 genetic background, which had not been examined previously for chromosome stability in culture. Organogenic callus cultures were intitated from immature embryos of F2 plants for several Oh43 ms isoline × A188 crosses. The chromosome constitution of 267 plants was investigated through meiotic analysis of plants regenerated either 3 to 4 or 8 to 9 months after culture initiation. No abnormalities were detected in 78 plants regenerated during the first period. During the second period, however, 91 of the 189 plants were cytologically abnormal. One hundred and eight aberrations were detected and most (96%) involved changes in chromosome structure such as interchanges (42%), deficiencies (35%), and heteromorphic pairs (19%). All deficiencies were intercalary. Also, most (51%) interchanges involved chromosome 6. An association between male-sterility factors and chromosome instability was not observed. Breakpoints were primarily on chromosome arms containing large blocks of heterochromatin such as knobs. Several abnormal plants from the same culture appeared to contain identical aberrations indicating the aberrations may trace to a single event. A hypothesis for the involvement of heterochromatin in chromosome breakage during in vitro culture is supported. Key words: Zea mays L., tissue culture, somaclonal variation, chromosome breakage, heterochromatin.

Cytogenetic stability of aneuploid maize tissue cultures

1986 ◽  
Vol 28 (3) ◽  
pp. 374-384 ◽  
Author(s):  
C. A. Rhodes ◽  
R. L. Phillips ◽  
C. E. Green
Keyword(s):  
Cell Walls ◽  
Chromosome Breakage ◽  
Pollen Sterility ◽  
Tissue Cultures ◽  
Culture Initiation ◽  
Single Chromosome ◽  
Recessive Mutations ◽  
Regenerated Plants ◽  
Genetic Stocks ◽  
Common Cell

Monosomic maize tissue cultures might be used to select recessive mutations of cellular traits. This strategy would avoid some of the problems encountered with haploid cultures such as lack of vigor, sterility of regenerated plants, and uncontrolled diploidization. Monosomic and other aneuploid plants were selected among progeny of W22 R/r-x1 crossed with genetic stocks containing recessive markers. The r-x1 allele induces aneuploidy at a frequency of about 15%. Immature tassels of selected plants were used to initiate totipotent tissue cultures. Plants were regenerated from the cultures over a period of 3 to 17 months after culture initiation. Meiotic karyotypes of microsporocytes and pollen sterility were analyzed in regenerated plants. At least 40% of the 161 plants regenerated from aneuploid cultures had altered karyotypes. This frequency was not related to culture age. Most alterations involved chromosome breakage rather than changes in chromosome number. Types of alterations included heteromorphic pairs (18.1%), translocations (12.5%), addition (10.6%) or loss (1.4%) of chromosomes, and genomic doubling (2.8%). Four euploid cultures, including one with a translocation, were equally unstable (49% with alterations among 115 plants). Euploid cultures gave rise to plants with translocations (12.3%), heteromorphic pairs (8.8%), and genomic doubling (29.2%), but no single chromosome additions or losses. Plants that shared a common distinctive karyotype, such as a specific translocation, were probably derived from a common cell line. Tassels with sectors of two different karyotypes were frequent in plants regenerated from aneuploid (20%) or euploid (33%) cultures. Coenocytic microsporocytes, which lacked cell walls between nuclei, were found in plants from monosomic-2, deficient-2L, and monosomic-6 cultures. Another aberration (23% of 144 regenerants) was lack of cell wall formation after the first and (or) second meiotic division, which was often followed by nuclear fusion. Karyotypic changes observed in this study rarely involved the monosomic chromosome, which means that monosomic tissue cultures could be used to select recessive mutants. Further tests would be needed to demonstrate that the selected gene resides in the monosomic chromosome.Key words: Zea mays, monosomic, trisomic, chromosome, somaclonal variation, karyotype.

CYTOGENETIC ANALYSIS OF PLANTS REGENERATED FROM OAT (AVENA SATIVA) TISSUE CULTURES; HIGH FREQUENCY OF PARTIAL CHROMOSOME LOSS

1982 ◽  
Vol 24 (1) ◽  
pp. 37-50 ◽  
Author(s):  
T. J. McCoy ◽  
R. L. Phillips ◽  
H. W. Rines
Keyword(s):  
Avena Sativa ◽  
High Frequency ◽  
Chromosome Instability ◽  
Chromosome Breakage ◽  
Chromosome Loss ◽  
Tissue Cultures ◽  
Meiotic Analysis ◽  
Regenerated Plants ◽  
Chromosomal Variability ◽  
Regeneration Cycle

The frequency and types of chromosomal variability in regenerated Avena sativa L. plants were assessed by detailed meiotic analysis on 655 regenerated plants. Tissue cultures were initiated from immature embryos of the varieties Lodi and Tippecanoe and maintained by monthly subculturing. Plants were regenerated from 4-, 8-, 12-, 16- and 20- month-old cultures. Regenerated plants with cytogenetic alterations were common, although Lodi cultures produced a higher frequency of cytogenetically abnormal plants at each regeneration cycle than Tippecanoe cultures. After four months in culture, 49% of Lodi regenerated plants were cytogenetically abnormal, whereas only 12% of Tippecanoe regenerated plants were abnormal. The frequency of cytogenetically abnormal, regenerated plants increased with culture age. After 20 months in culture 88% of Lodi regenerated plants and 48% of Tippecanoe regenerated plants were cytogenetically abnormal. The most common cytogenetic alteration was chromosome breakage, followed by loss of a chromosome segment resulting in a heteromorphic pair at diakinesis. Of the regenerated plants classified as cytogenetically abnormal, 41% of Lodi plants and 66% of Tippecanoe plants had lost a portion of one or more chromosomes. Other alterations included trisomy, monosomy and interchanges. Chromosome instability associated with oat tissue cultures has several possible uses.

In Vitro Cultivation of Cells of the Oyster, Crassostrea virginica

1966 ◽  
Vol 23 (4) ◽  
pp. 595-599 ◽  
Author(s):  
M. F. Li ◽  
James E. Stewart ◽  
R. E. Drinnan
Keyword(s):  
Cell Proliferation ◽  
Amniotic Fluid ◽  
Crassostrea Virginica ◽  
Salt Concentration ◽  
Cardiac Tissue ◽  
Cultured Cells ◽  
In Vitro Cultivation ◽  
Mammalian Tissue ◽  
Tissue Cultures

Cardiac tissue cells from oysters (Crassostrea virginica), cultured in a salt-enriched medium, apparently required a higher salt concentration for initiation of cell proliferation than that used for mammalian tissue cultures. The presence of human serum and bovine amniotic fluid enhanced the cell proliferation. Evidence of amitosis was observed in the cultured cells.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Preparation of cultured astrocytes for x-ray microanalysis

1989 ◽  
Vol 47 ◽  
pp. 988-989
Author(s):  
N.K.R. Smith ◽  
K.E. Hunter ◽  
P. Mobley ◽  
L.P. Felpel
Keyword(s):  
Cultured Cells ◽  
Elemental Content ◽  
Elemental Distribution ◽  
Sprague Dawley ◽  
X Ray ◽  
Cultured Astrocytes ◽  
Freeze Dried ◽  
Ultimate Objective

Electron probe energy dispersive x-ray microanalysis (XRMA) offers a powerful tool for the determination of intracellular elemental content of biological tissue. However, preparation of the tissue specimen , particularly excitable central nervous system (CNS) tissue , for XRMA is rather difficult, as dissection of a sample from the intact organism frequently results in artefacts in elemental distribution. To circumvent the problems inherent in the in vivo preparation, we turned to an in vitro preparation of astrocytes grown in tissue culture. However, preparations of in vitro samples offer a new and unique set of problems. Generally, cultured cells, growing in monolayer, must be harvested by either mechanical or enzymatic procedures, resulting in variable degrees of damage to the cells and compromised intracel1ular elemental distribution. The ultimate objective is to process and analyze unperturbed cells. With the objective of sparing others from some of the same efforts, we are reporting the considerable difficulties we have encountered in attempting to prepare astrocytes for XRMA.Tissue cultures of astrocytes from newborn C57 mice or Sprague Dawley rats were prepared and cultured by standard techniques, usually in T25 flasks, except as noted differently on Cytodex beads or on gelatin. After different preparative procedures, all samples were frozen on brass pins in liquid propane, stored in liquid nitrogen, cryosectioned (0.1 μm), freeze dried, and microanalyzed as previously reported.

Freeze-Fracture Studies of Membranes in Developing Sieve Elements in a Plant Tissue Culture

1980 ◽  
Vol 38 ◽  
pp. 636-637
Author(s):  
R. D. Sjolund ◽  
C. Y. Shih
Keyword(s):  
Plant Tissue ◽  
Cultured Cells ◽  
Freeze Fracture ◽  
Tissue Cultures ◽  
Sieve Elements ◽  
Intact Plants ◽  
Plant Tissue Cultures ◽  
Whole Plants ◽  
Energy Dependent ◽  
Similar Elements

The differentiation of phloem in plant tissue cultures offers a unique opportunity to study the development and structure of sieve elements in a manner that avoids the injury responses associated with the processing of similar elements in intact plants. Short segments of sieve elements formed in tissue cultures can be fixed intact while the longer strands occuring in whole plants must be cut into shorter lengths before processing. While iyuch controversy surrounds the question of phloem function in tissue cultures , sieve elements formed in these cultured cells are structurally similar to those of Intact plants. We are particullarly Interested In the structure of the plasma membrane and the peripheral ER in these cells because of their possible role in the energy-dependent active transport of sucrose into the sieve elements.

IN VITRO METHODS FOR THE STUDY OF THE ADENOHYPOPHYSIAL FUNCTIONS TO SECRETE GONADOTROPHIN

1971 ◽  
Vol 68 (1_Suppl) ◽  
pp. S27-S40 ◽  
Author(s):  
T. Kobayashi ◽  
T. Kigawa ◽  
M. Mizuno ◽  
T. Watanabe
Keyword(s):  
Cell Culture ◽  
Organ Culture ◽  
Cultured Cells ◽  
Cell Sheet ◽  
Short Term ◽  
Hypothalamic Extract ◽  
Numerous Cell ◽  
Single Cell Culture ◽  
Almost All

ABSTRACT There are several in vitro methods to analyse the function of the adenohypophysis or the mechanisms of its regulation. The present paper deals with single cell culture, organ culture and short term incubation techniques by which the morphology and gonadotrophin-secreting function of the adenohypophysis were studied. In trypsin-dispersed cell culture, the adenohypophysial cells showed extensive propagation to form numerous cell colonies and finally develop into a confluent monolayer cell sheet covering completely the surface of culture vessels. Almost all of the cultured cells, however, became chromophobic, at least at the end of the first week of cultivation, when gonadotrophin was detectable neither in the culture medium nor in the cells themselves. After the addition of the hypothalamic extract, gonadotrophin became detectable again, and basophilic or PAS-positive granules also reappeared within the cells, suggesting that the gonadotrophs were stimulated by the extract to produce gonadotrophin. In organ culture and short term incubation, the incorporation of [3H] leucine into the adenohypophysial cells in relation to the addition of hypothalamic extract was examined. It was obvious that the ability to incorporate [3H] leucine into the gonadotrophs in vitro was highly dependent upon the presence of the hypothalamic extract.

Improvement of effectiveness in maize breeding

2006 ◽  
Vol 54 (3) ◽  
pp. 351-358 ◽  
Author(s):  
P. Pepó
Keyword(s):  
Recurrent Selection ◽  
Genetic Manipulation ◽  
Field Testing ◽  
Tissue Cultures ◽  
Maize Breeding ◽  
Breeding Programmes ◽  
Speed Up ◽  
Selection For

Plant regeneration via tissue culture is becoming increasingly more common in monocots such as maize (Zea mays L.). Pollen (gametophytic) selection for resistance to aflatoxin in maize can greatly facilitate recurrent selection and the screening of germplasm for resistance at much less cost and in a shorter time than field testing. In vivo and in vitro techniques have been integrated in maize breeding programmes to obtain desirable agronomic attributes, enhance the genes responsible for them and speed up the breeding process. The efficiency of anther and tissue cultures in maize and wheat has reached the stage where they can be used in breeding programmes to some extent and many new cultivars produced by genetic manipulation have now reached the market.

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