Decision trees for sex estimation based on mandibular measurements: A CT study (original) (raw)
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Molecular Biology Reports, 2021
Plant breeding allows altering the genetic structure of plants to meet human needs. The use of radiation technology for inducing mutations and-thereby-new phenotypic variants has become increasingly common as a tool for developing new crops. The aim of this study was to determine the effective gamma irradiation dose for inducing mutations in purple carrot. For this purpose, increasing gamma radiation doses [0, 50, 100, 200, 300, 400, 500, and 600 Gy] were applied to purple carrot seeds. The irradiated seeds were sown in pots and the emergence and survival rates of the seedlings were analyzed. Considering plant emergence (%) as a response variable, the LD 50 dose was 387.5 Gy. Analysis of root length, root width (shoulder diameter) and plant height in control (0 Gy) and irradiated plants (50-600 Gy) revealed an inverse association between these morphological traits and radiation dose. SRAP and ISSR markers were used to identify DNA polymorphisms in irradiated and control plants. The range of amplicons per primer set revealed by ISSR and SRAP markers was 4-10 and 2-13, respectively. In ISSR analysis, the average Nei's gene diversity, Shannon's information index, and PIC value ranged from 0.13 to 0.25, from 0.20 to 0.35, from 1.39 to 1.67 for eight doses, respectively. In SRAP analysis, the average Nei's gene diversity, Shannon's information index, and PIC value were ranged from 0.15 to 0.25, from 0.23 to 0.37, from 0.43 to 0.58 for eight doses, respectively. Cluster analysis revealed three main groups; a) non-irratidated (control) plants, b) plants from the 600 Gy dose, and c) a third group with two subgroups: one with individuals from the lowest irradiation doses (50-200 Gy) and a second group with individuals from the highest irradiation doses (300-500 Gy).
Biologia Plantarum, 2016
The response of higher plants to ionising radiation depends on factors related to both radiation properties and plant features including species, cultivar, age, and structural complexity of the target organ. Adult plants of dwarf tomato were irradiated with different doses of X-rays to investigate possible variations in leaf morpho-anatomical traits, photosynthetic efficiency, and genomic DNA. In order to assess if and how responses depend on leaf developmental stage, we analysed two types of leaves; nearly mature leaves (L1) and actively developing leaves (L2), whose lamina size corresponded to 70 and 25 %, respectively, of the lamina size of the fully expanded leaves. The results show that the X-rays prevented full lamina expansion of the L2 leaves at all doses and induced early death of tissue of plants irradiated with doses higher than 20 Gy. Most anatomical modifications were not clearly dose-dependent and the radiation-induced increase in phenolic compounds was irrespective of dose. At high doses of X-rays (50 and 100 Gy), photochemical efficiency decreased significantly in both leaf types, whereas total chlorophyll content significantly decreased only in the L2 leaves. The random amplification of polymorphic DNA data show that the X-rays induced mutagenic effects in the L2 leaves even at low doses despite the absence of severe phenotypic alterations. Genetic structure found in the population of samples corroborates the results of anatomical and eco-physiological analyses: the 20 Gy dose seems to mark the threshold dose above which genetic alterations, structural anomalies, and perturbations in the photosynthetic apparatus become significant, especially in the actively expanding leaves.
Egyptian Journal of Desert Research
Paulownia tomentosa L) is the one useful trees in China. All parts of paulownia tree (leaves, flowers, wood, bark, roots and seeds) have been used for many medicinal and industrial purposes. Buds were cultured on ¾ Murashige and Skoog (MS) solid medium supplemented with 0.2 mg/l benzyl adenine and 0.1 mg/l kinetin. The survival percentage and mean shoot length of irradiated plantlets with gamma radiation doses of 10, 20, 30, 40 and 50 Gy were calculated after eight weeks. The results showed a decrease in the survival percentage and mean shoot length by increasing gamma radiation doses. The lethal dose was 50 Gy and the optimal dose for explant survival was 10 Gy. Anatomical and ultrastructure of un-irradiated and irradiated paulownia were examined based on photonic and electron microscopy for plantlets leaves after 16 days from culturing. Anatomical studied of leaf surface showed variations in epidermal cells, trichomes, stomata and mesophyll cells. The ultrastructure sections showed formation of plastoglobule and starch granules which indicates a reduced carbon metabolism at sublethal dose of 40 Gy.
CYTOLOGIA, 1982
A. H. Sparrow and his coworkers have, in a long series of papers, formulated a broad generalization relating certain cellular characteristics to radio sensitivity for a wide range of organisms (Sparrow, Underbrink and Sparrow 1967, Underbrink, Sparrow and Pond 1968). Sparrow et al. (1965) pointed out that tolerance of species to chronic exposure of ionizing radiation is related to the size of genetic targets, and also to the average length of the mitotic cycle. Organisms with long cycle times and long periods in G2, for instance, would offer potential for greater radiation damage than organisms with short G2 duration and short cycle times. Yamakawa and Sparrow (1966) measured the radiosensitivity of pollen grains based upon dose-dependent pollen abortion and reported a linear relationship between interphase chromosome volume and radiosensitivity. Sparrow et al. (1968), Under brink et al. (1968) and Price et al. (1973) have expanded this generalization to many other organisms; as the interphase chromosome volume, or nuclear volume, increases, the radio sensitivity of the organisms also increases. Other correlations have been reported by Van't Hof and Sparrow (1963b) and Van't Hof (1964, 1974a) such as DNA content with mitotic cycle duration, and duration of S. Bennett (1973) summarized many studies which show a similar relationship between the duration of meiosis, its stages and nuclear DNA content. Bennett (1974) also examined the role nuclear characters play in morphogenesis. He drew correlations from the literature showing the relationship of DNA content (nucleotype) and many plant metabolic size and development characters. Van't Hof (1974b) discusses a property of plant root meristems whereby cells exposed to carbohydrate starvation become arrested according to a characteristic ratio of G1 and G2 nuclei. This condition known as stationary phase is species specific and may be induced by other forms of stress sources as well (Rost 1977). In the current study we intend to compare the effect of acute irradiation at doses ranging from 100R to 1000R in four species with different stationary phase ratios. Two questions will be addressed: 1) Will the delay of entry of cells into
Journal of Environmental Radioactivity, 2020
The purpose of this work is to highlight the effects of ionizing radiation on the genetic material in higher plants by assessing both adaptive processes as well as the evolution of plant species. The effects that the ionizing radiation has on greenery following a nuclear accident, was examined by taking the Chernobyl Nuclear Power Plant disaster as a case study. The genetic and evolutionary effects that ionizing radiation had on plants after the Chernobyl accident were highlighted. The response of biota to Chernobyl irradiation was a complex interaction among radiation dose, dose rate, temporal and spatial variation, varying radiation sensitivities of the different plants' species, and indirect effects from other events. Ionizing radiation causes water radiolysis, generating highly reactive oxygen species (ROS). ROS induce the rapid activation of detoxifying enzymes. DeoxyriboNucleic Acid (DNA) is the object of an attack by both, the hydroxyl ions and the radiation itself, thus triggering a mechanism both direct and indirect. The effects on DNA are harmful to the organism and the long-term development of the species. Dose-dependent aberrations in chromosomes are often observed after irradiation. Although multiple DNA repair mechanisms exist, double-strand breaks (DSBs or DNA-DSBs) are often subject to errors. Plants DSBs repair mechanisms mainly involve homologous and non-homologous dependent systems, the latter especially causing a loss of genetic information. Repeated ionizing radiation (acute or chronic) ensures that plants adapt, demonstrating radioresistance. An adaptive response has been suggested for this phenomenon. As a result, ionizing radiation influences the genetic structure, especially during chronic irradiation, reducing genetic variability. This reduction may be associated with the fact that particular plant species are more subject to chronic stress, confirming the adaptive theory. Therefore, the genomic effects of ionizing radiation demonstrate their likely involvement in the evolution of plant species.
Impact assessment of long-term chronic radiation exposure on plant populations
Studies that examine biological effects on non-human biota in natural settings provide a unique opportunity for obtaining information about the potential biological hazard associated with radioactive contamination. The results of long-term field study in the Bryansk Region, Russia, affected by the Chernobyl accident are discussed. Plant populations growing in areas with relatively low levels of pollution are characterized by the increased level of both cytogenetic alterations and genetic diversity. In particular, radioactive contamination of the plants' environment activates genetic mechanisms, changing a population's resistance to exposure. However, there are radioecological situations where enhanced radioresistance has not evolved or has not persisted. A development of a system for protection of the environment from ionizing radiation should be based on a clear understanding of these effects and their contribution to response of populations.