The development of functional nanomaterials exhibiting cost-effectiveness, biocompatibility and biodegradability in the form of nanoadditives, nanofertilizers, nanosensors, nanopesticides and herbicides, etc., has attracted considerable attention in the field of agriculture. Such nanomaterials have demonstrated the ability to increase crop production, enable the efficient and targeted delivery of agrochemicals and nutrients, enhance plant resistance to various stress factors and act as nanosensors for the detection of various pollutants, plant diseases and insufficient plant nutrition. Among others, functional magnetic nanomaterials based on iron, iron oxide, cobalt, cobalt and nickel ferrite nanoparticles, etc., are currently being investigated in agricultural applications due to their unique and tunable magnetic properties, the existing versatility with regard to their (bio)functionalization, and in some cases, their inherent ability to increase crop yield. This review article provides an up-to-date appraisal of functionalized magnetic nanomaterials being explored in the agricultural sector.

Gamma-ray irradiation introduces single and/or double strand breaks into the DNA molecule of the cells. In the case of mammalian cells, these breaks are beimg repaired in general during the first hr following exposure to ionizing radiation. The article reports on the results obtained from testing the ability of cultured lymphocytes from patients with Down's syndrome to repair radiationinduced DNA single-strand breaks. The ability to repair was deduced from the study of the DNA sedi~nentatioa proNes in alkaline sucrose gradients. It was found that lymphocytes from Down's syndrome patients are less efficient in repairing single strand DNA breaks than are lymphocytes from normal individuals. This significantly increased fraction of unrepaired DNA strand breaks might be associated with the unusually high level of radiation-induced chromosome aberrations as compared with normals. SpeculationThe present work was carried out to fmd out whether the increased frequency of dicentrics and rings observed in human lymphocytes from patients with Down's syndrome is related to the presence of a DNA single-strand break repair mechanism of reduced capacity.Patients who exhibit chromosome abnormalities involving an extra chromosome. such as trisomy-21 or Klincfelter's syndrome (XXY), have an increased susceptibility to malignancy &d to Xor yray induced chromosomal aberrations (12, 13).The observation that cultured lymphocytes, obtained from patients with Down's syndrome are twice as sensitive to the induction of chromosome dicentrics and rings by y-rays (13,21) could be an indication that a defect in the system by which genetic damage is repaired is responsible for the increased chromosomal abnomalities and risk of developing leukemia.We studied the ability of lymphocytes from patients with Down's syndrome to repair y-ray-induced damage by means of the DNA sedimentation profiles in alkaline sucrose gradients. It has been shown previously that mammalian cells of various origins carry mechanisms by which single or double breaks induced by ionizing radiation on the DNA molecule can be rejoined (5) and that the ability to rejoin strand breaks appears to be a general property of the rapidly dividing cells (9).Although human cell lines obtained from individuals having different types of inherited disorders, like xerodema pigmentosum (XP), ataxia telangiectasia, and Fanwni's anemia, were found to be associated with defects in the ability to repair certain kinds of physical or chemical damage on their DNA (3,8,11,16,17, IS), there is no evidence of any known human cell line capable of dividing to have a defect in their ability to rejoin single-or doublestrand breaks introduced into their DNA by X-or y-rays (8).It is shown by means of the DNA sedimentation profiles in alkaline sucrose gradients that cells from three patients with Down's syndrome were unable to repair y-ray-induced, singlestrand breaks in their DNA. MATERIALS AND METHODS CELL CULTURESFive ml of blood were obtained from normal individuals and patients with Down's syndrome (a...

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