Unequal Separation Research Articles

Effect of Treatments of Colchicine, Diethyl Sulphate and Triethylamine in Tomato (<I>Lycopersicon esculentum</I> Mill.)

The present investigation was undertaken in one variety of Tomato, Best of All, to compare the cytogenetic effects of treatments of seeds of tomato with colchicine, diethyl sulphate and triethylamine and also to compare the morphological and physiological effects of these chemicals.Lowest number of seeds germinated from diethyl sulphate treatment. Plants originating from colchicine, diethyl sulphate and triethylamine treatments showed many variant types. Interesting among these were those showing spotting on leaves originating from diethyl sulphate treatment, dwarf ones originating from colchicine and diethyl sulphate treatments and those with abnormal leaves originating from treatment with all the three chemicals.Mitotic irregularities included clumped chromosomes and fragments at metaphase and bridges and fragments at anaphase while in meiosis clumped chromosomes, univalents, trivalents and quadrivalents were noted at metaphase I. Anaphase I irregularities included cells with fragments, bridges with or without fragments, lagging chromosomes and unequal separation of chromosomes. In metaphase II cells with aneuploid chromosome numbers and those with fragments were noticed while in anaphase II cells were found with fragments and unequal separation of chromosomes.The importance of detecting interesting mutants in the Ma generation and the importance of finding translocations and inversions have been pointed out.

Assessment of Bio-physiological damages and cytological aberrations in cowpea varieties treated with gamma rays and sodium azide.

The assessment of mutagen induced biological damage forms an important study in determining the mutagenic potency and genotypic sensitivity, a vital aspect in mutation breeding programs. A prior assessment of lethal dose (LD50), mutagen induced biological damage (alterations in bio-physiological traits and frequency of cytological aberrations) is a prerequisite for determining an optimum mutagen dose in a successful mutation breeding experiment. Therefore, in a multi-year project of mutation breeding, two widely cultivated varieties of cowpea viz., Gomati VU-89 and Pusa-578, were treated with gamma (γ) rays and sodium azide (SA) doses. The results reflected a proportionate increase in bio-physiological damages with the increase in mutagenic doses and caused a substantial reduction in mean seed germination and seedling height. Different cytological aberrations such as cytomixis, univalents, chromosome stickiness, precocious separation, unequal separation, bridges, laggards, disturbed polarity, dyads, triads, and polyads were observed in both varieties. All the mutagen doses induced a broader spectrum of cytological aberrations with varying frequencies.

Assessment of the Mutagenic and Cytotoxic Ability of Azanza Garckeana (F.Hoffm), Using Allium Cepa (L) Assay

The study on the assessment of the mutagenic and cytotoxic ability of Azanza garckeana leaf and fruit extracts on the root tip of Allium cepa was evaluated; aqueous leaf and fruit extract of A. garckeana were collected and dried, and pounded into powder. For the root growth inhibition and cytological analysis, four concentrations of each extract, viz: 5g,10g, 15g, and 20g, including positive and negative control, were considered, and the result was determined for each extract using a graph to indicate the maximum and minimum EC50 (Effective concentration). The EC ranged from 10 g/ml with a root length of 3 cm for A. garckeana leaf extracts, 10g/ml with a root length of 2.5 cm for A. garckeana fruits extracts, A range of chromosomal aberrations such as polyploidy, dissolution, vagrant metaphase, binucleate, laggard, nuclear lesion, fragmentation, chromosome gap, anaphase bridge, micronuclei, unequal separation, were observed in all the plant’s extracts. Statistically, the chromosomal aberrations observed in the root tip cells of A. cepa treated with the leaf extracts of A. garckeana shows that 10g is statistically significantly different from 5g (P = 0.026) and negative control, 15g is significantly different from 5g (P = 0.000) and 10g (P = 0.026). However, as the concentration increased to 20g, there was a significant difference in the percentage of aberrations from 5g (P =0.0000) to 10g (P = 0.005), but not significantly different from 15g (P =0.0553). Whereas fruit extract shows that 10g is higher than 5g but has no statistical significance (P =0.101). 15g is significantly different from 5g (P =0.101) but not significantly different from 10g (P =0.055), 20g (P =0.331), and positive control (P =0.845). As the concentrations of the plant extracts increased to 10%, 15%, and 20%, there was a progressive increase in the percentage of aberrant cells and a decrease in the number of dividing cells, suggesting that low concentrations of A. garckeana extracts should be used in traditional medicine production.

The Balassa-Samuelson model with job separations

We incorporate sectoral job separation rates in a small open economy model to examine the Balassa-Samuelson (B-S) effect. Unequal separation rates give rise to compensating wage differentials. We simulate the model for Japan and replicate a feature of its economy that the nontradeables sector has higher wages and a higher separation rate compared to the tradeables sector. With productivity growth in the tradeables sector, labour moves from the tradeables sector to the nontradeables sector if tradeables and nontradeables are complements in consumption. The B-S effect is dampened. With a higher separation rate in the nontradeables sector, higher wages in the nontradeables sector amplifies this labour movement. Nevertheless, unemployment always falls due to a positive income effect. In contrast, the effect of productivity growth in the nontradeables sector is to lower the real exchange rate and raise unemployment.

Chromosome behavior during meiosis in pollen mother cells from Saccharum officinarum \xd7 Erianthus arundinaceus F1 hybrids

BackgroundIn recent years, sugarcane has attracted increasing attention as an energy crop. Wild resources are widely used to improve the narrow genetic base of sugarcane. However, the infertility of F1 hybrids between Saccharum officinarum (S. officinarum) and Erianthus arundinaceus (E. arundinaceus) has hindered sugarcane breeding efforts. To discover the cause of this infertility, we studied the hybridization process from a cytological perspective.ResultsWe examined the meiotic process of pollen mother cells (PMCs) in three F1 hybrids between S. officinarum and E. arundinaceus. Cytological analysis showed that the male parents, Hainan 92–77 and Hainan 92–105, had normal meiosis. However, the meiosis process in F1 hybrids showed various abnormal phenomena, including lagging chromosomes, micronuclei, uneven segregation, chromosome bridges, and inability to form cell plates. Genomic in situ hybridization (GISH) showed unequal chromatin distribution during cell division. Interestingly, 96.70% of lagging chromosomes were from E. arundinaceus. Furthermore, fluorescence in situ hybridization (FISH) was performed using 45S rDNA and 5S rDNA as probes. Either 45S rDNA or 5S rDNA sites were lost during abnormal meiosis, and results of unequal chromosomal separation were also clearly observed in tetrads.ConclusionsUsing cytogenetic analysis, a large number of meiotic abnormalities were observed in F1. GISH further confirmed that 96.70% of the lagging chromosomes were from E. arundinaceus. Chromosome loss was found by further investigation of repeat sequences. Our findings provide insight into sugarcane chromosome inheritance to aid innovation and utilization in sugarcane germplasm resources.

The effect of nuclear radiation on mutation chromosomes of shallot cells (Allium cepa)

Environmental pollution by nuclear radiation has been known to endanger chromosomes. This research aims to analyze the abnormal forms of root shallot chromosomes which are irradiated by nuclear with various levels of radiation. This is a quasi-experimental research. The treatment group was given radiation through nuclear reactors at a dose of 11.88 rad, 8.69 rad, 2.01 rad, 1.28 rad, 1.15 rad, 0.26 rad, 0.00034 rad, 0.00016 rad, while the control group was without radiation. The staining of the preparations was carried out using Acetocarmine 2%. Reading preparations using a microscope with a magnification of 400x. The results of the study showed the emergence of various forms of chromosomal abnormalities. Abnormal forms that appear are pole to pole arrangement chromosome, unequal separation, binucleate cell, pulverized ball metaphase, sticky anaphase with broken bridge, chromosome rosette, abnormal chromosome fragment, early cell plate formation at late anaphase, sticky metaphase, binucleate cell with a bridge, chromosome fragments, binucleate cells, chromosome gaps, ball anaphases with a diagonal scattered anaphase bridge, and aberrant grouping at anaphases in a giant cell. The novelty of this preliminary study is that chromosomal abnormalities in the onion roots were found even in the very low radiation group. Large-scale research is required and their effects if eaten by animals or humans need further research.

The Cyto-morphological Studies in Physalis minima Linn.

Cyto-morphological studies in a diploid natural population of Physalis minima Linn were done. It was a diploid natural population recorded behind Jal Mandir on Parasnath hills. Qualitative and quantitative parameters were investigated. Ten morphological characters like height of the plant, number of branches per plant, number of branches from main stem, number of nodes, length of internodes, number of heads per plant, length of leaf, breadth of leaf, length/breadth ratio of leaf andlength of petiole were recorded and statistically analyzed. Cytologically, the population showed, gametic number as n= 12. Most of the pollen mother cells were found to be normal; however, some abnormalities were also recorded. Clumping of chromosomes recorded in both meiotic phases i,e. metaphase-I and anaphase-I. Along with it, at metaphase-I, the anomalies recorded as formation of univalents, multivalents and precocious separation of chromosomes. Anaphase-I showed chromosomal laggards, simple chromosomal bridges and unequal separation of chromosomes as anomalies. The half chiasma per chromosome was 0.87. Pollen sterility was 6.00 percentages.

Biological characteristics and cytological studies on anther abortion of male sterile <italic>Camellia crassocolumna</italic>

The purpose of this study was to explore the flower morphology, anther and pollen abortion time and its cytological characteristics in male sterile plants of C. crassocolumna . The flowering process, floral morphology, anther structure, meiosis and microsporogenesis of male sterile (M350) and fertile plants (M352) of C. crassocolumna were observed by stereomicroscopy, paraffin section, chromosome preparation and DAPI staining. The results showed that the wild tea plant had a perfect flower, its anthers were tetrasporangiate shaped like a butterfly, with an anther wall development of basic type. It tapetal cells were binuclear, forming secretory cells at the tetrad stage, and degrading during mononuclear pollen stage. After the meiosis I, meiosis II and cytokinesis, pollen mother cells developed into tetrahedral tetrads. Microspores were triangular, and mature pollen was two-celled. The stamens of male sterile flowers developed normally in the early stage of flower bud development, and there was no difference between sterile and fertile flowers, while in the late stage of flower bud development, filaments were curved, anthers adhered and shriveled, anthers could not release pollen. The tapetal cells of male sterile flowers were proliferation abnormally and disordly at the meiosis of stage pollen mother cells, and the degradation of tapetum was delayed during the mononuclear and binucleate pollen periods. During meiosis of pollen mother cells of male sterile flowers, there were some abnormal appearances, such as chromosome ring, lagging chromosomes, chromosome bridges, chromosomal deletion, scattered chromosomes, unequal separation, micronucleus and abnormal tetrad. In sterile plants, the microspore cytoplasm was disorder, pollen grains adhered to each other at the mononuclear stage, pollen wall crumpled and deformed, cytoplasm and nucleus of pollen were blurred, the mature pollen cells were hollow and sunken. Taken together, the floral organ morphology of male sterile plants in C. crassocolumna belongs to stamen collapse type and anther abnormality type. The development of anthers is blocked from meiosis of pollen mother cells to uninucleate pollen stage, belonging to pollen mother cell abortion type and uninucleate pollen abortion type. Mononuclear period is the main period of anther abortion. Tapetum degradation delayed, chromosomal abnormalities of pollen mother cells in meiosis, and abnormal development of microspores and pollens, might be the main reasons for anther abortion in male sterile plants of C. crassocolumna .

Production of pollenless triploid lily hybrids from Lilium pumilum DC. × ‘Brunello’

Embryo rescue was employed to create four pollenless Asiatic triploid lily hybrids, ‘PB1’, ‘PB2’, ‘PB3’ and ‘PB4’, from the cross of Lilium pumilum DC. (2n = 2x = 24) and the Asiatic lily cultivar ‘Brunello’ (2n = 4x = 48). Cytological observation confirmed that all four hybrids were triploid (2n = 3x = 36) and that the progeny and their parents all shared the 3B karyotype. Some abnormal behavior was observed in the triploid hybrids during pollen mother cell meiosis, including chromosome bridges, lagging chromosomes, micronuclei and unequal separation. The hybrids ‘PB1’ and ‘PB2’ had malformed anthers that were pollenless and could not release pollen grains, but the other two hybrids, ‘PB3’ and ‘PB4’, had a few pollen grains in anthers that were almost normal in shape. The stem diameter, leaf index, inner perianth length, outer perianth length and flower diameter of the four hybrids were all intermediate between the respective traits of the parents. However, plant height, stem diameter and flower number per plant were superior in hybrid plants compared to both parents. Flower color, hairs on bud, flower direction and tepal shape showed wide segregation among the hybrids. Hybrid ‘PB2’ was also fragrant. The four triploid hybrids can be used as garden plants directly or as new genetic resources for breeding pollenless lily cultivars.

Effect of Chemical Mutagens on Chromosomal behavior of Allium cepa L

Effect of chemical mutagens was studied in mitotic cells of Allium cepa L. For this purpose root tips were treated with saturated solution of peradichloro benzene, 0.2% EMS and 0.2 % freshly prepared colchicines for 4hours to 9hours.The studies revealed a wide range of chromosomal abnormalities such as stickiness, laggards, chromosomal bridge, unequal separation, nuclear budding, multinuclear cells etc.The parentage of chromosomal abnormalities in different mitotic stages were calculated on mitotic index, frequency of phases and percentage of abnormalities in mitosis. The chromosomal abnormalities increase with increase duration of treatment. The results showed that in colchicines and EMS more than 50% abnormalities ware observed after 8 hrs of treatment, while in PDB it takes 6 hours treatment. Minimum MI was recorded as 65% in controlled cells. In colchicines and EMS treated cells 0.9.5%, 20% MI ware observed after 8hrs of treatment. Whereas in PDB maximum 23% MI was recorded in cells treated for 6hrs.

Cytogenetic characterization of a triploid mulberry (Morus spp.) cultivar Suvarna-2

Mulberry exehibits a high degree of polyploidy ranging from haploidy to docosaploidy and its various species are being cultivated for foliage to practice sericulture and edible fruits. Triploid mulberries for sericulture porpuse and higher polyploids are proved to be superior. The cultivar Suvarna-2 is an improved high leaf yielding triploid in south India. The meiotic behavior of this cultivar has been presented here. Meiosis was highly irregular. Various anomalies such as univalent, bivalents, trivalent, hexavalent, loose association, unequal separation and precocious movement of chromosomes and laggards have been observed in pollen mother cells. These irregularities prevented the formation of viable gamete that leads to pollen sterility.

Genotoxicity effects of silver nanoparticles on wheat (Triticum aestivum L.) root tip cells

The distribution and use of nanoparticles have rapidly increased over recent years, but the available knowledge regarding their mode of action, ecological tolerance and biodegradability remains insufficient. Wheat (Triticum aestivum L.) is the most important crop worldwide. In the current study, the effects of silver nanoparticles (AgNPs) obtained from two different sources, namely, green and chemical syntheses, on chromosomal aberrations and cell division were investigated. Wheat root tips were treated with four different AgNP concentrations (10, 20, 40 and 50 ppm) for three different exposure durations (8, 16 and 24 h), and the different concentrations of the nanoparticles were added to the tested grains until the root lengths reached 1.5–2 cm. For each concentration, the mitotic indexes (%) were obtained from an analysis of ~ 2000 cells. The treated root-tip cells exhibited various types of chromosomal aberrations, such as incorrect orientation at metaphase, chromosomal breakage, metaphasic plate distortion, spindle dysfunction, stickiness, aberrant movement at metaphase, fragmentation, scattering, unequal separation, scattering, chromosomal gaps, multipolar anaphase, erosion, and distributed and lagging chromosomes. These results demonstrate that the root tip cells of wheat can readily internalize the AgNPs and that the internalized AgNPs can interfere with the cells’ normal function.

Entransy analysis on optimization of a double-stage latent heat storage unit with the consideration of an unequal separation

A double-stage Latent Heat Storage (LHS) unit is transformed from a single-stage LHS unit, by separating the unit into two portions filled with different Phase Change Materials (PCMs). In this paper, a double-stage LHS unit is optimized with entransy analysis, with the consideration of an unequal separation. The criterion formulas of optimum separation as well as the distribution of coefficient c is derived. The valid range of melting temperature Tm_1 in the first portion is determined. The influence of Tm_1 on the performance of the optimal double-stage LHS unit is discussed. It is concluded that entransy dissipation rate is reduced with the optimum distribution. With the increase of Tm_1, the optimum c decreases in the first portion and increases in the second portion. The optimum c in the first portion is larger than that in the second portion, at the low end of Tm_1; while it is smaller, at the high end of Tm_1. The melting temperature Tm_2 in the second portion varies with Tm_1 as a U-shape curve. An equal separation is the best for a double-stage LHS unit. However, when the melting temperature available deviates from the designated value, the optimum distribution of c should be considered.

A comprehensive analysis of BRCA2 gene: focus on mechanistic aspects of its functions, spectrum of deleterious mutations, and therapeutic strategies targeting BRCA2-deficient tumors.

BRCA2is the main susceptibility gene known to be involved in the pathogenesis of breast cancer. It plays an important role in maintaining the genome stability by homologous recombination through DNA double-strand breaks repairing, by interacting with various other proteins including RAD51, DSS1, RPA, MRE11, PALB2, and p53. BRCA2-deficient cells show the abnormalities of chromosome number. BRCA2 is also found to be involved in centrosome duplication specifically in the metaphase to anaphase transition. Inactivation or depletion of BRCA2 leads to centrosome amplification that results in unequal separation of chromosomes. BRCA2 localizes with central spindle and midbody during telophase and cytokinesis. Inactivation or depletion of BRCA2 leads to multinucleation of cell. Around 2000 mutations have been reported in BRCA2 gene. BRCA2-deficient tumors are being taking into consideration for targeted cancer therapy by using different inhibitors like poly ADP-ribose polymerase and thymidylate synthase. The present review focusses on the role of BRCA2 in various critical cellular processes based on the mechanistic approaches. Mutations reported in the BRCA2 gene in various ethnic groups till date have also been compiled with an insight into the functional aspects of these alterations. The therapeutic strategies for targeting BRCA2-deficient tumors have also been targeted.

Changes in hemp secondary fiber production related to technical fiber variability revealed by light microscopy and attenuated total reflectance Fourier transform infrared spectroscopy.

Interest in hemp (Cannabis sativa L.) is increasing due to the development of a new range of industrial applications based on bast fibers. However the variability of bast fiber yield and quality represents an important barrier to further exploitation. Primary and secondary fiber content was examined in two commercial hemp varieties (Fedora 17, Santhica 27) grown under contrasted sowing density and irrigation conditions. Both growing conditions and hemp varieties impact stem tissue architecture with a large effect on the proportion of secondary fibers but not primary fibers. Attenuated total reflectance infrared spectroscopy allowed the discrimination of manually-isolated native primary fibers and secondary fibers but did not reveal any clustering according to growing conditions and variety. Infrared data were confirmed by wet chemistry analyses that revealed slight but significant differences between primary and secondary fiber cell wall composition. Infrared spectroscopy of technical fibers obtained after mechanical defibering revealed differences with native primary, but not secondary fibers and also discriminated samples obtained from plants grown under different conditions. Altogether the results suggested that the observed variability of hemp technical fibers could be partially explained by i) differences in secondary fiber production and ii) differential behavior during mechanical defibering resulting in unequal separation of primary and secondary fibers.

Cytogenetical Study of Induced Desynaptic Variants in <i>Phaseolus vulgaris</i> L.

The cytological screening of gamma ray treated plants revealed few desynaptic plants where an enhanced frequency of univalents were found at metaphase I along with few bivalents. The desynaptic plants were obtained at 200 Gy dose of gamma rays and were characterised as weak and medium strong type. The univalents remained unpaired till later meiotic stages and resulted in the unequal separation of chromosomes at anaphase I. The unequal separation of chromosomes as a consequence of desynapsis lead to the formation of micronuclei and gametes with imbalanced chromosomes, thus affecting the post-meiotic stages also. The desynaptic plants possess very few pods and acquire high pollen inviability. The study suggests the ability of gamma rays in the creation of male sterile lines in Phaseolus vulgaris L. The gamma rays either act on the genes responsible for synapsis and chiasma formation or disrupt the synaptonemal complex affecting chiasmate dissociation. The desynaptic mutants could be used as a potential source for gathering information on chiasma maintenance mechanism as well as to study the genetic mechanism and consequences of male sterility in plants. Further, the male sterile lines could also be profitably utilized in hybridization breeding programmes to produce hybrid seeds.

Fano Scattering: Manifestation of Acoustic Phonons at the Nanoscale.

Size-dependent asymmetric low-frequency Raman line shapes have been observed from silicon (Si) nanostructures (NSs) due to a quantum confinement effect. The acoustic phonons in Si NSs interact with an intraband quasi-continuum to give rise to Fano interaction in the low-frequency range. The experimental asymmetric Raman line shape has been explained by developing a theoretical model that incorporates the quantum-confined phonons interacting with an intraband quasi-continuum available in Si NSs as a result of discretization of energy levels with unequal separation. We discover that a phenomenon similar to Brillouin scattering is possible at the nanoscale in the low-frequency regime and thus may be called "Fano scattering" in general. A method has been proposed to extract information about nonradiative transitions from the Fano scattering data where these nonradiative transitions are involved as an intraband quasi-continuum in modulation with discrete acoustic phonons.

English

Two mulberry varieties, namely, S 34 and Tr- 10 were selected for cytomorphological studies. Stomatal frequency, somatic chromosome number, ploidy level and meiotic behaviour were studied for these varieties. S 34 is diploid with 2n=28 and Tr- 10 is triploid with 2n=42 chromosomes. Meiosis was irregular. Various anomalies like univalents, bivalents, trivalents laggards, loose association and unequal separation of chromosomes were observed in some pollen mother cells (PMCs) studied. Stomatal frequency was found to be lesser in triploid when compared to diploid variety. Keywords: Mulberry ( Morus spp.), stomatal frequency, diploid, triploid, mitosis, meiosis African Journal of Biotechnology , Vol 13(22) 2203-2207

Interaction of cobalt nanoparticles with plants: a cytogenetical aspect

In vivo cytogenetical assay in root meristems has been carried out to study the effect of cobalt and cobalt oxide nanos on active mitotic index and chromosomal aberrations of green manure crop, Sesbania pea. Nanoparticles are nanosize particles and can enter freely into the cells and can interfere in cell's normal function. Studies to justify its probable after-effects on living beings are scarce. So it is important to study its effect on living beings. For this purpose, seeds of Sesbania cannabina variety ND-1 were soaked in distilled water for 14 hours and after soaking, the seeds were treated with three different treatments, namely, nano-cobalt, nano-cobalt oxide and ethanol for three hours. The treated root meristems exhibited various types of chromosomal aberrations such as metaphasic plate distortion, unorientation at metaphase, breaking of chromosomes, fragmentation, spindle dysfunctioning, stickiness, scattering, precocious movement at metaphase and bridge, unequal separation, multiple bridge, fragmentation, scattering, laggard and unorientation at anaphase, etc.

Cytogenetical Studies in Some Triploid Mulberry Varieties (Moraceae)

Most Morus species are diploid, having 28 chromosomes, but a few species, specifically, M. tiliafolia Makino, Morus cathyana and M. nigra L., are higher polyploidy. In these species, the chromosome number varies from 2n=28 to 2n=308, with ploidy level from x to 22x. In the present study, three diploid mulberry varieties, namely, V1, S13 and S34 have been analyzed for detailed meiotic studies. Based on chromosome configuration and other meiotic behaviour, x=14 has been considered as the basic number of the genus. Meiosis shows marginal differences. Various meiotic abnormalities, such as the occurrence of one large chromosome at metaphase I, unequal separation at anaphase I, the presence of laggards and precocious movement of chromosomes at anaphase II, and two micronuclei at tetrad, have been observed. The low pollen fertility and seed sets may be due to irregular chromosomal pairing and separation rather than due to genetic or physiological causes. © 2013 The Japan Mendel Society.