Metal tolerance in plants: Molecular and physicochemical interface determines the "not so heavy effect" of heavy metals.

An increase in technological interventions and ruthless urbanization in the name of development has deteriorated our environment over time and caused the buildup of heavy metals (HMs) in the soil and water resources. These heavy metals are gaining increased access into our food chain through the plant and/or animal-based products, to adversely impact human health. The issue of how to restrict the entry of HMs or modulate their response in event of their ingress into the plant system is worrisome. The current knowledge on the interactive-regulatory role and contribution of different physical, biophysical, biochemical, physiological, and molecular factors that determine the heavy metal availability-uptake-partitioning dynamics in the soil-plant-environment needs to be updated. The present review critically analyses the interactive overlaps between different adaptation and tolerance strategies that may be causally related to their cellular localization, conjugation and homeostasis, a relative affinity for the transporters, rhizosphere modifications, activation of efflux pumps and vacuolar sequestration that singly or collectively determine a plant's response to HM stress. Recently postulated role of gaseous pollutants such as SO2 and other secondary metabolites in heavy metal tolerance, which may be regulated at the whole plant and/or tissue/cell is discussed to delineate and work towards a "not so heavy" response of plants to heavy metals present in the contaminated soils.

Prevalence of Antiretroviral Therapy Use among HIV/AIDS Patients in a District Hospital.

INTRODUCTION: Prevention of Human Immunodeficiency Virus infection is a high priority for the government of Nepal, so the government has been scaling up Anti Retroviral Therapy centers throughout the country. The objective of our study was to find out the prevalence of people living with Human Immunodeficiency Virus infection on Anti Retroviral Therapy service. METHODS: This descriptive cross-sectional study was done in Lamjung district hospital, from May 2017 till August 2017 after taking ethical clearance from the institutional review committee. The study was done in 96 patients and convenience sampling was done. The data collected was entered in Microsoft Excel and analyzed in Statistical Packages for Social Sciences version 17.0, point estimate at 95% Confidence Interval was calculated along with frequency and proportion for binary data. RESULTS: Out of the total 109 patients enrolled at the hospital, 85 (78%) were on ongoing Anti Retroviral Therapy. The predominant age group among patients using Anti Retroviral Therapy was 25-34 years 27 (31.7%) and the five most common clinical manifestation/opportunistic infections were fever 40 (47.1%), diarrhea 34 (40%), fatigue/generalized weakness 32 (37.6%), loss of appetite 25 (29.4%) and headache 18 (21.2%) among them. Out of total patients, 14 (12.8%) of our patients were under 14 years of age. We found 71 (83.6%) of the patients continued the original first-line regimen and in 14 (16.5%) one or two drugs were substituted in the original regimen. CONCLUSIONS: Our study showed a similar prevalence of people living with Human Immunodeficiency Virus infection on Anti Retroviral Therapy service with the other studies done within Nepal.

Uninhibited biosynthesis and release of phytosiderophores in the presence of heavy metal (HM) favors HM remediation.

Production of phytosiderophore (PS) has been causally related to iron-deficiency tolerance in cereals. However, PS can also chelate heavy metal and thus may represent a viable phytoextraction strategy on contaminated soils. Two separate experiments were conducted to assess the affect of heavy metal on phytosiderophore biosynthesis and their release in the rhizosphere of wheat. Root exudates were collected from 10-day-old wheat seedlings raised on Fe-deficient nutrient solution in the presence of 2.5, 5.0, and 10 mM concentration of different heavy metals (Cd, Pb, and Ni) for 3-day period, for the phytosiderophore and the heavy metal analysis. Plant uptake of respective heavy metal was positively correlated with the heavy metal concentration of the nutrient solution. Phytosiderophore release was positively influenced in the presence of the heavy metal. Increasing concentration of Cd, Pb, and Ni showed positive correlation with the PS release until 5 mM concentration followed by a decline at 10 mM. However, a higher induction of PS release was measured in wheat seedlings treated with Cd and Pb than Ni. Further, transcript expression analysis of nicotianamine synthase (NAS) and nicotianamine amino transferase (NAAT), involved in phytosiderophore biosynthesis, was done in roots of 10-day-old Fe-deficient wheat subjected to 2.5, 5.0, and 10 mM of Cd, Pb, and Ni. Both NAS and NAAT were expressed not only under Fe deficiency but also in the presence of Cd, Pb, and Ni. Sequencing of partial cDNA of NAS revealed a nucleotide length of 998 bp, while multiple sequence alignment of NAS with HvNAS revealed 92% sequence similarity. This study irrevocably shows that phytosiderophore biosynthesis and release are not impaired in the presence of heavy metal and that phytosiderophore mediates the uptake of toxic heavy metal.

Probing occurrence of phenylpropanoids in Morinda citrifolia in relation to foliar diseases.

Accumulation of phenolic compounds in cell walls of different plant organs leading to increased lignification is an early defence response of plants against biotic stress. The aim of this work was to delineate occurrence of cell wall-bound (CWB) phenolic compounds in Morinda citrifolia leaves. Alkaline hydrolysis of the cell wall material of leaf tissues yielded 4-coumaric acid (4-CA) as the major bulk of the phenolic compounds in all Morinda germplasms. Next in line was 4-hydroxybenzoic acid. Other phenolics identified were vanillic acid, 4-hydroxybenzaldehyde, vanillin and ferulic acid. Concentrations of all the CWB phenolics were highest in the germplasm CHN-5, followed by the germplasm CHN-1. Incidentally, these two Morinda germplasms recorded lowest incidence of foliar diseases. Significantly higher amounts of 4-CA in combination with other phenolics may be the reasons for lowest incidence of foliar diseases in CHN-5 and CHN-1 germplasms of M. citrifolia.