Understanding the role of starch sheath layer in graviception of Alternanthera philoxeroides: a biophysical and microscopical study.

Plants' ability to sense and respond to gravity is a unique and fundamental process. When a plant organ is tilted, it adjusts its growth orientation relative to gravity direction, which is achieved by a curvature of the organ. In higher, multicellular plants, it is thought that the relative directional change of gravity is detected by starch-filled organelles that occur inside specialized cells called statocytes, and this is followed by signal conversion from physical information to physiological information within the statocytes. The classic starch statolith hypothesis, i.e., the starch accumulating amyloplasts movement along the gravity vector within gravity-sensing cells (statocytes) is the probable trigger of subsequent intracellular signaling, is widely accepted. Acharya Jagadish Chandra Bose through his pioneering research had investigated whether the fundamental reaction of geocurvature is contractile or expansive and whether the geo-sensing cells are diffusedly distributed in the organ or are present in the form of a definite layer. In this backdrop, a microscopy based experimental study was undertaken to understand the distribution pattern of the gravisensing layer, along the length (node-node) of the model plant Alternanthera philoxeroides and to study the microrheological property of the mobile starch-filled statocytes following inclination-induced graviception in the stem of the model plant. The study indicated a prominent difference in the pattern of distribution of the gravisensing layer along the length of the model plant. The study also indicated that upon changing the orientation of the plant from vertical position to horizontal position there was a characteristic change in orientation of the mobile starch granules within the statocytes. In the present study for the analysis of the microscopic images of the stem tissue cross sections, a specialized and modified microscopic illumination setup was developed in the laboratory in order to enhance the resolution and contrast of the starch granules.

Elemental distribution in urban sediments of small waterbodies and its implications: a case study from Kolkata, India.

The impacts of elemental pollution in sediments of freshwater bodies are of particular concern in rapidly urbanizing cities of the developing world and have been extensively studied in rivers and lakes. The current study is an attempt to highlight the importance of smaller waterbodies, which happen to form a natural network in cities, for assessing the contamination status of sediments. The distribution of elements (Al, Ca, Fe, K, Mg, S, Si, Ti, Ba, Mn, Sr, V, As, Cr, Cu, Ni, Pb and Zn) in sediments of 15 ponds and 6 canals was studied to understand the overall pollution status and the associated ecological risk to aquatic organisms. Geochemical indices revealed Cr, Cu, Pb and Zn to be the principal elements of concern. The mean concentration of Cr, Cu, Pb and Zn was 308, 174, 76.9 and 446 mg kg-1, respectively. Ecological risk assessment revealed that Cr in 86% sites, Ni in 52% sites, Cu and Zn in 28% sites and Pb in 10% sites were associated with possible ecological toxicity. The findings suggest that multielemental concentration in sediments of ponds and canals could effectively distinguish between pristine and polluted sites and suitably identify the main elements of concern to support cost-efficient waste management solutions customized to both the sites and elements of concern.

Iron assessment tests: transferrin receptor vis-à-vis zinc protoporphyrin.

OBJECTIVES: To review and compare the biochemical, analytical, and clinical features of two relatively new tests for assessing iron status and diagnosing iron disorders, namely, the serum transferrin receptor concentration (sTfR) and the erythrocyte zinc protoporphyrin/heme ratio (ZnPP/H). To consider the merits of each test for the diagnosis of iron disorders with emphasis on iron-deficient erythropoiesis, especially in the clinically important preanemia stage of iron depletion. CONCLUSIONS: Although the basic biochemical mechanisms underlying the two tests are very different, both of these tests are noteworthy because they are considered to reflect iron status in the bone marrow. The principal advantage to serum transferrin receptor is the lack of a response to anemia of chronic disease (ACD), which affects other iron status indicators, for example, ferritin and transferrin saturation. The principal advantage to erythrocyte zinc protoporphyrin is low cost, but point-of-care testing and simplicity can also be advantages. Both serum transferrin receptor and erythrocyte zinc protoporphyrin have been demonstrated to be useful in a variety of clinical situations. Serum transferrin receptor can be best used in diagnosing iron disorders, especially for patients with pathologies that may affect iron metabolism. Erythrocyte zinc protoporphyrin can be best used as a primary screening test for assessing iron status, especially in patients likely to have uncomplicated iron deficiency. While these applications are primary, both tests are more broadly useful, for example, in monitoring iron therapy.