scholarly journals Cytoplasmic segregation in onion root tip cells and formation of vacuoles

2015 ◽  
Vol 43 (4) ◽  
pp. 541-547 ◽  
Author(s):  
Tomasz J. Wodzicki ◽  
Claud L. Brown
Keyword(s):  
Central Area ◽  
Root Tip ◽  
Root Tips ◽  
Onion Root ◽  
Early Stages ◽  
Meristematic Region ◽  
The Matrix ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Outer Unit

Onion root tips were studied both with transmission and scanning electron microscope. The cells in the meristematic region of initials were found to be little vacuolated. At early stages of cell differentiation areas free of ribosomes are segregated in the cytoplasm. No (or only incomplete) membranes delimiting such areas could be distinguished in most cases. Seemingly, the membraneous structures may form later or simultaneously with the progress of breakdown of biostructure of the cytoplasm in the segregated area. The microscopic image of cytoplasm in the segregated areas (and even of the vacuolar sap at early stages of vacuole formation) resembles the matrix of cytoplasm populated with ribosomes. The cytoplasm in the whole central area is segregated at early stages of differentiation of root cap cells. The process of autophagic vacuoles formation in which the preexisting endomembranes seemingly are involved is described. It is proposed that such vacuoles may form after separation of two unit membranes of a cisternae surrounding a portion of the cytoplasm or an organelle, followed by independent growth of an outer unit membrane.

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.

scholarly journals Effect of triazophos on mitotic activity and chromosomal behavior in root meristems of Allium cepa L.

2010 ◽  
Vol 6 ◽  
pp. 4-7 ◽  
Author(s):  
Archana Pandey ◽  
Shyam R Sakya
Keyword(s):  
Mitotic Activity ◽  
Allium Cepa ◽  
Root Meristem ◽  
Plant Science ◽  
Root Tip ◽  
Allium Cepa L ◽  
Meristematic Region ◽  
Cellular Abnormalities ◽  
Tip Cells ◽  
Root Tip Cells

Effect of triazophos (an organophosphorous insecticide) on mitotic activity and chromosomal behavior in the meristematic region of root tip cells of Allium cepa L. was assessed. The insecticide showed mitotic depression and positive chromo-toxic effects. Abnormalities, such as stickiness, plasmolysed cells, equatorial plate shifting, polar shifting, irregular chromosome arrangement, precocious arms formation, bridge formation, C-metaphase, fragmentation of chromosomes, unequal cytokinesis, diagonal cytokinesis, delayed cytokinesis and formation of binucleated cells, were recorded in the chemically pretreated root meristem. Key-words: chromosomal and cellular abnormalities; cytotoxic effect; mitotic index; phase indices.DOI: 10.3126/botor.v6i0.2903 Botanica Orientalis - Journal of Plant Science (2009) 6: 4-7

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.

INATE AND PHOTO-CONTROLLED MITOTIC RHYTHMS IN ONION ROOT-TIP CELLS

1973 ◽  
Vol 15 (4) ◽  
pp. 667-670 ◽  
Author(s):  
Richard C. Bishop ◽  
Richard M. Klein
Keyword(s):  
Mitotic Activity ◽  
Diurnal Rhythm ◽  
Low Temperatures ◽  
Root Tip ◽  
Fluorescent Light ◽  
Onion Root ◽  
Seed Imbibition ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Red Radiation

A four-peaked diurnal rhythm in mitotic activity of dark-grown onion root-tip cells is initiated upon seed imbibition, damps rapidly and is lost within 5 days. It is abolished by continuous white fluorescent light, by continuous blue, green or red radiation, by low temperatures, high osmotica or anoxia. Photoperiodic light controls the well-known two-peaked persistent rhythm. The nature of the zeitgeber for either the inate or the photoperiodically-controlled rhythms is unknown.

Cytological investigations on onion root-tip cells treated with some cigarette smoke constituents

1974 ◽  
Vol 65 (5) ◽  
pp. 311-313 ◽  
Author(s):  
P. R. BHALLA ◽  
R. C. ARNOLD ◽  
P. S. SABHARWAL
Keyword(s):  
Cigarette Smoke ◽  
Root Tip ◽  
Onion Root ◽  
Tip Cells ◽  
Root Tip Cells

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.

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