ABSTRACT
Food security relies on plant productivity and plant's resilience to climate change driven environmental stresses. Plants employ diverse adaptive mechanisms of stress-signalling pathways, antioxidant defense, osmotic adjustment, nutrient homeostasis and phytohormones. Over the last few decades, silicon has emerged as a beneficial element for enhancing plant growth productivity. Silicon ameliorates biotic and abiotic stress conditions by regulating the physiological, biochemical and molecular responses. Si-uptake and transport are facilitated by specialized Si-transporters (Lsi1, Lsi2, Lsi3, and Lsi6) and, the differential root anatomy has been shown to reflect in the varying Si-uptake in monocot and dicot plants. Silicon mediates a number of plant processes including osmotic, ionic stress responses, metabolic processes, stomatal physiology, phytohormones, nutrients and source-sink relationship. Further studies on the transcriptional and post-transcriptional regulation of the Si transporter genes are required for better uptake and transport in spatial mode and under different stress conditions. In this article, we present an account of the availability, uptake, Si transporters and, the role of Silicon to alleviate environmental stress and improve plant productivity.
Subject(s)
Plants , Silicon , Biological Transport , Plant Development , Stress, PhysiologicalABSTRACT
Plants overcome the effect of Na+ toxicity either by excluding Na+ at the plasma membrane or by sequestering them into the vacuoles. Influx of Na+ ions into the plant vacuoles is usually driven by H+ generated by vacuolar-type H+-ATPase as well as vacuolar proton pyrophosphatse (VPPase). In the present study, we have developed Bacopa monnieri transgenics via Agrobacterium tumefaciens containing the recombinant vector pCAMBIA2300-SbVPPase gene. Transformants were produced using nodal explants. Transformants were confirmed by PCR and DNA blot analysis. qPCR analysis showed higher transcript levels of SbVPPase compared to untransformed control (UC). Higher VPPase activity was recorded in transgenics compared to UC. Under 150 mM salt stress, transgenic shoots showed enhanced Na+ accumulation with better biomass production, increased glycine betaine content, and total soluble sugar levels than UC. Transgenic shoots showed 2.9-3.8-folds lower levels of malondialdehyde content indicating lesser membrane damage. Increase in antioxidant enzyme activities (1.4-3.2-folds) was observed in transgenics compared to UC. Transgenics also displayed 7.3-9.0-folds enhanced accumulation of the medicinally important compound bacoside A. Increased biomass production, accumulation of Na+, osmolytes (glycine betaine, sugars etc.), and elevated antioxidant enzyme activities indicate better osmotic adjustment in transgenics by compartmentalization of Na+ into the vacuoles under salt stress conditions. Thus, overexpression of SbVPPase in Bacopa alleviated salt stress by sequestering Na+.
ABSTRACT
Fibreoptic bronchoscopy with bronchial aspiration* washings and biopsy was performed in 104 patients suspected clinically and radio logically of having pulmonary tuberculosis diagnostic yield in 9230% (96/104) cases. Diagnostic yield for tuberculosis was in 69.22% (72/104)cases, it includes positive aspiration and washings smear in 38.46%(40/l04) patients,positive mycobacteriai culture alone in 26.92% (28/104) casesandpositive biopsy in 3*84% (4/ 104) patients, Non-tuberculous conditions like pneumonia and bronchogenic carcinoma were diagnosed in 19.23% (20/104) cases and 3.84% (4/104) cases respectively. These results suggest that in areas with high prevalence of tuberculosis, bronchoscopy should be performed for early diagnosis and initiation of therapy in sputum smear-negative cases of pulmonary tuberculosis.
ABSTRACT
Reconstruction of the ossicular mechanism using a tragal cartilage autograft frequently presents problems, including displacement of the cartilage graft, maintenance of firm and accurate contact between the graft and ossicular remnants, and loss of stiffness of the graft. To avoid these problems, we have used the cartilage graft and overlying perichondrium of appropriate size, with a tunnel made between the outer perichondrium and the cartilage to accommodate remnants of the incus or handle of the malleus. The graft has a small perichondrial flap on the other end for firm anchorage to the arch of the stapes or the footplate. This allows the cartilage graft to be firmly anchored with the adjacent ossicular remnants. The presence of perichondrium with the graft helps to maintain nutrition, stiffness, and the configuration of the cartilage. With minor modifications, we have used this technique in 115 patients to reconstruct different types of ossicular defects, with commendable hearing results. Of the 115 operated ears, an air-bone gap closure within 10 dB was found in 14.8%, within 15 dB in 34.8%, and within 20 dB in 24.4% of ears. In another 20.8% of cases, the air-bone gap closure remained in the range of 25 dB or less. The longest follow-up was 13 years 7 months. The presented technique is easy and effective and solves most of the problems of cartilage ossiculoplasty.
