CHROMOSOME ABERRATIONS PRODUCED BY 5-BROMODEOXYURIDINE WITH CONCURRENT EXPOSURE TO LONG WAVELENGTH UV IN ZEA MAYS ROOT TIP CELLS

1977 ◽  
Vol 19 (3) ◽  
pp. 447-459 ◽  
Author(s):  
R. S. Verma ◽  
J. E. Cummins ◽  
D. B. Walden
Keyword(s):  
Zea Mays ◽  
Chromosome Aberrations ◽  
Cesium Chloride ◽  
Root Tip ◽  
Chromosome Damage ◽  
Root Tips ◽  
Long Wavelength ◽  
Small Pool ◽  
Tip Cells ◽  
Root Tip Cells

The influence of bromodeoxyuridine (BrUrdR) on the pattern and level of chromosome damage in Zea mays L. root tip cells is described. In some experiments long wavelength ultraviolet light was employed to convert the bromodeoxyuridine in DNA to its photoproduct. BrUrdR treatment produced a marked decrease in the mitotic index and a high proportion of the mitotic cells bore chromosome damage. Following a BrUrdR treatment of 5 h the proportion of damaged cells increased from 20% to 60% during the 20 h following treatment; then the proportion decreased sharply to less than 20%. Root tips treated as above followed by an exposure to long wavelength ultraviolet radiation (UV) had a proportion of damaged cells (80% at 20 h) only slightly greater than those not exposed to UV up to 20 h after treatment. Unlike the unirradiated BrUrdR substituted root tips, the proportion of damaged cells remained high 25 h after treatment. Furthermore, the spectrum of chromosome aberrations differed between irradiated and unirradiated BrUrdR substituted cells. Root tips exposed to long wavelength UV alone showed some damage that was limited to a stage in the cell cycle of irradiated root tips. Analysis of the BrUrdR treated corn DNA by cesium chloride density centrifugation showed that BrUrdR substitution for thymidine in DNA was extensive. Further experiments demonstrated that a large BrUrdR pool was not carried into the rounds of replication following BrUrdR removal from the medium. Nevertheless a small pool of halogenated pyrimidine was observable after BrUrdR removal from the medium.

scholarly journals THE CYTOCHEMICAL LOCALIZATION OF ASCORBIC ACID IN ROOT TIP CELLS

1956 ◽  
Vol 2 (1) ◽  
pp. 87-92 ◽  
Author(s):  
William A. Jensen ◽  
Leroy G. Kavaljian
Keyword(s):  
Ascorbic Acid ◽  
Cell Surface ◽  
Silver Nitrate ◽  
Ribonucleic Acid ◽  
Root Tip ◽  
Root Tips ◽  
Cytochemical Localization ◽  
Meristematic Cells ◽  
Tip Cells ◽  
Root Tip Cells

The intracellular distribution of ascorbic acid was studied in frozen-dried root tips of Allium cepa and Vicia faba by the silver nitrate procedure. The sites of the ascorbic acid as indicated by the deposited silver appear as spherical (0.2 to 0.6 µ in diameter) cytoplasmic particles. The site appears to have small amounts of lipides and to be rich in ribonucleic acid. These particles are concluded to be submicroscopic in size and associated, in the elongating cell, with the cell surface. In the meristematic cells they appear fewer in number and are distributed throughout the cytoplasm.

scholarly journals Cytogenetic impact of sodium chloride stress on root cells of Vigna radiata L. seedlings

2020 ◽  
Vol 45 (2) ◽  
Author(s):  
Jabeen Farheen ◽  
Simeen Mansoor
Keyword(s):  
Mitotic Division ◽  
Root Tip ◽  
Ecological Problem ◽  
Root Tips ◽  
Root Cells ◽  
Nacl Concentration ◽  
Seedling Roots ◽  
Metaphase Stage ◽  
Tip Cells ◽  
Root Tip Cells

AbstractObjectivesThe high salinization stress to seedling is the substantial ecological problem in the ongoing era. It negatively influences the growth that retard mitotic division by enhancing aberrations in nuclear chromatin. In the light of these views, the current work was designed to investigate the response of Vigna seedlings root tip cells to the presence of NaCl ions.Materials and methodsNM-92 and NM19-19 seeds were imbibed separately in distilled water for 24 h and allowed to grow into 0, 50, 150, 250, and 350 mM NaCl solution for 24 h. Excised root tips were stained, and slides were scored at 100× objective for the mitotic index (MI) and chromosomal aberrations.ResultsOur data demonstrated that as NaCl molarity increased, the MI was declined along with various chromatin abnormalities. The 150 mM of NaCl showed more lagging (69%) of chromosomes during anaphase in NM19-19. The highest stickiness at metaphase stage (68%) was found in 250 mM NaCl in variety NM19-19. However, both varieties were differed non-significantly for c-mitosis that was recorded 99% at 350 mM NaCl concentration.ConclusionsThe NaCl ions toxicity induced various cytological anomalies in seedling roots that adversely affect the growth of Vigna seedlings.

A RING CHROMOSOME IN AN F1 HYBRID BETWEEN WHEAT AND AGROPYRON

1959 ◽  
Vol 37 (6) ◽  
pp. 1271-1276 ◽  
Author(s):  
Koichiro Tsunewaki
Keyword(s):  
Ring Chromosome ◽  
Root Tip ◽  
Root Tips ◽  
F1 Hybrid ◽  
Ring Chromosomes ◽  
Differential Elimination ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Mitotic Behavior

A plant having 41 normal rod-shaped chromosomes and a ring chromosome was found among hexaploid.F1 hybrids from a wheat–Agropyron cross. Cytological investigations were carried out to determine the mitotic behavior of this ring chromosome.The investigations revealed that most of the possible products of the breakage–fusion–bridge cycle known to occur in a ring chromosome were present in root tip cells. The fact that a rod-shaped chromosome is not derived from a ring chromosome in the cycle was confirmed, because no metaphase cells examined had 42 or more rod-shaped chromosomes.About 80% of the ring chromosomes were eliminated from the root tips of the seedling after 26 days. The size of the ring chromosome did not appear to influence the rate of elimination. The polyploid nature of the plant may account for the rapid, non-differential elimination of this chromosome.

A DICENTRIC WHEAT CHROMOSOME IN DIVISION

1954 ◽  
Vol 32 (3) ◽  
pp. 491-502 ◽  
Author(s):  
J. W. Morrison
Keyword(s):  
Extra Chromosome ◽  
Wheat Chromosome ◽  
Chiasma Formation ◽  
Root Tip ◽  
Anther Wall ◽  
Somatic Variation ◽  
Root Tips ◽  
The One ◽  
Tip Cells ◽  
Root Tip Cells

A dicentric chromosome was observed in the F2 progeny of an interspecific wheat cross. It is suggested that: the dicentric arose from breakage and fusion of two nonhomologous univalent chromosomes in the preceding meiosis. Because only a few bridges were observed in root tips, anther wall tissue, and in sectioned ovaries, it was concluded that the dicentric persisted in the plant because of parallel separation of the chromatids. Somatic variation was observed in some root tip cells. At meiosis, the dicentric was invariably paired with its two homologues and both centromeres were effective in orientation on the plate. Chains-of-five and even rings-of-five were formed in one spike. In another, the loss of one chromosome arm prevented such associations but several forms of trivalents occurred. In one spike, internal chiasmata were formed in the intercentric region of the chromosome. On the chiasmatype theory of crossing over this should have caused bridges at succeeding stages. Besides the lack of bridges, in some cells at AI there was definite evidence that the dicentric was breaking apart and forming an extra chromosome. To explain this phenomenon it is suggested that the effect of the one centromere was nullified by the other and the full consequences of chromatid breakage and reunion in chiasma formation were not fulfilled.

scholarly journals INCORPORATION OF C14-LABELED MALEIC HYDRAZIDE INTO THE ROOT-TIP CELLS OF ALLIUM CERNUUM, VICIA FABA, AND TRADESCANTIA PALUDOSA

1961 ◽  
Vol 10 (4) ◽  
pp. 567-575 ◽  
Author(s):  
John J. Callaghan ◽  
Paul Grun
Keyword(s):  
Vicia Faba ◽  
Maleic Hydrazide ◽  
Root Tip ◽  
Nucleolar Localization ◽  
Root Tips ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Tradescantia Paludosa

Allium cernuum, Vicia faba, and Tradescantia paludosa were treated by root immersion in maleic hydrazide (1 mM/liter) labeled with C14 (C14-MH) for 1 hour to determine the location within the cell to which MH moves during various periods of time after treatment. Root tips were fixed 24 hours, 48 hours, 72 hours, and 3 weeks after treatment. Autoradiographs of root tips squashed 24 to 72 hours after fixation showed that C14-MH was distributed throughout the nuclei and was particularly concentrated in the nucleoli. The nucleolar localization of the chemical was transitory, fixations made 3 weeks after treatment showing well labeled nuclei many of which completely lacked label in the nucleoli. The chromosomes seen in mitotic divisions of all three species had the same amount of label in euchromatic as heterochromatic areas. Since the chemical was not accumulated preferentially in heterochromatic areas, it seems likely that the reported specificity of MH for the breakage of heterochromatin can not be due to preferential heterochromatic incorporation.

The effects of nano-TiO2 on seed germination, development and mitosis of root tip cells of Vicia narbonensis L. and Zea mays L

2010 ◽  
Vol 13 (6) ◽  
pp. 2443-2449 ◽  
Author(s):  
Monica Ruffini Castiglione ◽  
Lucia Giorgetti ◽  
Chiara Geri ◽  
Roberto Cremonini
Keyword(s):  
Zea Mays ◽  
Seed Germination ◽  
Zea Mays L ◽  
Root Tip ◽  
Nano Tio2 ◽  
Vicia Narbonensis ◽  
Tip Cells ◽  
Root Tip Cells

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.

scholarly journals New chromosome numbers in Pilocarpus Vahl (Rutaceae)

2000 ◽  
Vol 14 (1) ◽  
pp. 11-24
Author(s):  
Ladislau A. Skorupa
Keyword(s):  
Chromosome Numbers ◽  
Room Temperature ◽  
Basic Number ◽  
Root Tip ◽  
Root Tips ◽  
Chromosome Counts ◽  
Pre Treatment ◽  
First Time ◽  
Tip Cells ◽  
Root Tip Cells

Chromosome counts for eight species of Pilocarpus Vahl (Rutaceae) a native of Brazil are reported for the first time. Chromosome numbers were determined from mitotic root tip cells of seedlings derived from field collections and grown in the greenhouse. Feulgen staining was used. Initial pre-treatment of root tips was done by using a saturated aqueous solution of alpha-bromonapthalene for two hours at room temperature (20-25ºC). Chromosome numbers of 2n=44 and 2n=88 were determined for the examined taxa. The present results suggest the occurrence of tetraploidy in P. spicatus St.-Hil. and P. carajaensis Skorupa, and a possible basic number x=22 to the genus Pilocarpus.

scholarly journals Supra-physiological levels of gibberellins/DELLAs modify the root cell size/number and the root architecture in root tips of A. thaliana seedlings. Connections to the root hair patterning and abundance

2021 ◽  
Author(s):  
Iva McCarthy-Suarez
Keyword(s):  
Cell Size ◽  
Root Hair ◽  
Root Architecture ◽  
Root Hairs ◽  
Root Tip ◽  
Root Tips ◽  
Root Epidermis ◽  
Size Number ◽  
Tip Cells ◽  
Root Tip Cells

A previous study (McCarthy-Suarez, 2021) showed that growing A. thaliana seedlings for 5 days under excessive levels of gibberellins (GAs)/DELLAs altered the arrangement, shape and frequency of root hairs in root tips. Because no changes in the distribution or number of root hairs occurred when the gai-1 (gibberellin-insensitive-1) DELLA was over-expressed at the root epidermis, it was concluded that the GAs/DELLAs might regulate the root hair patterning and abundance in A. thaliana seedlings by acting from the root sub-epidermal tissues. In the present study, microscopy analyses showed that excessive levels of GAs/DELLAs also modified the size and number of root tip cells in A. thaliana seedlings. While excessive DELLAs shortened and widened the root epidermal, cortical, endodermal and pericycle cells, excessive GAs, excepting the epidermal cells, generally narrowed them. However, no changes of root cell size occurred when gai-1 was over-expressed at the root epidermis. In addition, high levels of DELLAs often induced extra cells at the root epidermis, cortex, endodermis and pericycle, whereas high levels of GAs sometimes induced extra cells at the root cortex and pericycle. On the other hand, excessive levels of DELLAs enhanced the outgrowth of lateral roots in root tips, unlike excessive levels of GAs. Thus, the results of this study suggest that supra-physiological levels of GAs/DELLAs might modify the size/number of root tip cells by acting from the root sub-epidermal tissues. This, in turn, might impact on the patterning and abundance of root hairs and on the root architecture.

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