K. Muthuchelian

Multifunctional HER2-Antibody Conjugated Polymeric Nanocarrier-Based Drug Delivery System for Multi-Drug-Resistant Breast Cancer Therapy

Nanotechnology-based medical approaches have made tremendous potential for enhancing the treatment efficacy with minimal doses of chemotherapeutic drugs against cancer. In this study, using tamoxifen (Tam), biodegradable antibody conjugated polymeric nanoparticles (NPs) was developed to achieve targeted delivery as well as sustained release of the drug against breast cancer cells. Poly(D,L-lactic-co-glycolic acid) (PLGA) NPs were stabilized by coating with poly(vinyl alcohol) (PVA), and copolymer polyvinyl-pyrrolidone (PVP) was used to conjugate herceptin (antibody) with PLGA NPs for promoting the site-specific intracellular delivery of Tam against HER2 receptor overexpressed breast cancer (MCF-7) cells. The Tam-loaded PVP-PLGA NPs and herceptin-conjugated Tam-loaded PVP-PLGA NPs were characterized in terms of morphology, size, surface charge, and structural chemistry by dynamic light scattering (DLS), Transmission electron microscopy (TEM), ζ potential analysis, 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FT-IR) spectroscopy. pH-based drug release property and the anticancer activity (in vitro and in vivo models) of the herceptin conjugated polymeric NPs were evaluated by flow cytometry and confocal image analysis. Besides, the extent of cellular uptake of drug via HER2 receptor-mediated endocytosis by herceptin-conjugated Tam-loaded PVP-PLGA NPs was examined. Furthermore, the possible signaling pathway of apoptotic induction in MCF-7 cells was explored by Western blotting, and it was demonstrated that drug-loaded PLGA NPs were capable of inducing apoptosis in a caspase-dependent manner. Hence, this nanocarrier drug delivery system (DDS) not only actively targets a multidrug-resistance (MDR) associated phenotype (HER2 receptor overexpression) but also improves therapeutic efficiency by enhancing the cancer cell targeted delivery and sustained release of therapeutic agents.

Low night temperature effects on photosynthetic performance on two grapevine genotypes

The functional activities of the photosynthetic apparatus of two grapevine genotypes (Vitis vinifera L. cvs. Müller-Thurgau and Lagrein) were investigated after low night temperature (LNT) treatment for 7 d. LNT caused important reductions of the net photosynthetic rate (PN) of Lagrein plants due to non-stomatal components. These non-stomatal effects were not evident in Müller-Thurgau. At LNT treatment, the contents of photosynthetic pigments decreased significantly in Lagrein, but in Müller-Thurgau the contents of chlorophyll (Chl) remained unchanged whereas the contents of carotenoids (Car) increased. An increase and decrease of Chl a/b was shown in Mü ller-Thurgau and Lagrein stressed plants, respectively. RuBPC activity and content of soluble proteins were also significantly reduced in Lagrein. Under LNT treatment, photosystem (PS) 2 was markedly more inhibited in Lagrein than in Müller-Thurgau. The decrease in PS 2 activity in Lagrein was mostly due to the marked loss of D1, 47, 43, 33, 28-25, 23 and 17 kDa proteins determined by immunological and SDS-PAGE studies.

Effect of water deficit on photosynthetic and other physiological responses in grapevine (Vitis vinifera L. cv. Riesling) plants

The grapevine (Vitis vinifera L. cv. Riesling) plants subjected to water deficit were studied for changes in relative water content (RWC), leaf dry mass, contents of chlorophyll (Chl), total leaf proteins, free amino acids, and proline, and activities of ribulose-1,5-bisphosphate carboxylase (RuBPC), nitrate reductase (NR), and protease. In water-stressed plants RWC, leaf dry matter, Chl content, net photosynthetic rate (PN), and RuBPC and NR activities were significantly decreased. The total leaf protein content also declined with increase in the accumulation of free amino acids. Concurrently, the protease activity in the tissues was also increased. A significant two-fold increase in proline content was recorded.

Shade effect alters leaf pigments and photosynthetic responses in Norway spruce (Picea abies L.) grown under field conditions

The contents of chlorophyll (Chl) and carotenoids (Car) per fresh mass were lower in shade needles than in sun needles. Ribulose-1,5-bisphosphate carboxylase (RuBPC) activity and contents of soluble proteins were also significantly lower in shade needles. In isolated thylakoids, a marked lower rate of whole chain and photosystem (PS) 2 activities were observed in shade needles. Smaller lower rate of PS1 activity was also observed in shade needles. The artificial exogenous electron donors, diphenyl carbazide (DPC) and NH2OH, significantly restored the loss of PS2 activity in shade needles. Similar results were obtained when Fv/Fm was evaluated by Chl fluorescence measurements. The marked lower rate of PS2 activity in shade needles was due to the lower contents of 47, 33, 28–25, 23, and 17 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the watersplitting complex was diminished significantly in shade needles.

Iron deficiency induced changes on the donor side of PS II in field grown grapevine (Vitis vinifera L. cv. Pinot noir) leaves

Abstract In this work we have studied the influence of lime-induced iron deficiency on some features of the thylakoids and PS II membranes from grapevine ( Vitis vinifera L. cv. Pinot noir) plants grown in calcareous soils. Changes in photosynthetic activities and PS II membrane polypeptides were investigated. When various photosynthetic electron transport activities were analyzed in isolated thylakoids, a major decrease in the rate of whole chain (H 2 O→MV) electron transport was observed in chlorotic leaves. Such reduction was mainly due to the loss of PS II activity. Smaller inhibition of PS I activity was also observed in chlorotic leaves. The artificial electron donors, DPC and NH 2 OH markedly restored the loss of PS II activity in chlorotic leaves. The same results were obtained when variable fluorescence/maximum fluorescence (Fv/Fm) was evaluated by chlorophyll (Chl) fluorescence measurements. The marked loss of PS II activity in chlorotic leaves was evidently due to the loss of D1, 33, 28–25, and 23 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the D1 protein of the PS II reaction centre and of the 33 kDa protein of the water-splitting complex was diminished significantly in chlorotic leaves.

Triacontanol can protect Erythrina variegata from cadmium toxicity

Summary The simultaneous effect of 0, 10, 100 and 1000 μmol/L Cd 2+ [Cd(NO 3 ) 2 × 4H 2 O] and 1 mg kg −1 (H 2 O) triacontanol [TRIA] spray on certain parameters of growth, pigments, starch, 14 CO 2 fixation, ribulose-1,5-bisphosphate carboxylase (Rubisco), nitrate reductase (NR) and photosynthesis in Erythrina variegata seedlings was studied. With increasing Cd 2+ concentration in the nutrient solution the monitored activities decreased. When the seedlings were subsequently sprayed with triacontanol the cadmium effect was partially or completely reversed indicating that TRIA can protect from cadmium toxicity.

Photoinhibition of Photosynthesis in Sun and Shade Grown Leaves of Grapevine (Vitis vinifera L.)

The degree of photoinhibition of sun and shade grown leaves of grapevine was determined by means of the ratio of variable to maximum chlorophyll (Chl) fluorescence (Fv/Fm) and electron transport measurements. The potential efficiency of photosystem 2 (PS2), Fv/Fm, markedly declined under high irradiance (HI) in shade leaves with less than 10 % of F0 level. In contrast, Fv/Fm ratio declined with about 20 % increase of F0 level in sun leaves. In isolated thylakoids, the rate of whole chain and PS2 activity in HI shade and sun leaves was decreased by about 60 and 40 %, respectively. A smaller inhibition of photosystem 1 (PS1) activity was also observed in both leaf types. In the subsequent dark incubation, fast recovery was observed in both leaf types that reached maximum PS2 efficiencies similar to non-photoinhibited control leaves. The artificial exogenous electron donors DPC, NH2OH, and Mn2+ failed to restore the HI-induced loss of PS2 activity in sun leaves, while DPC and NH2OH were significantly restored in shade leaves. Hence HI in shade leaves inactivates on the donor side of PS2 whereas it does at the acceptor side in sun leaves, respectively. Quantification of the PS2 reaction centre protein D1 and the 33 kDa protein of water splitting complex following HI-treatment of leaves showed pronounced differences between shade and sun leaves. The marked loss of PS2 activity in HI leaves was due to the marked loss of D1 protein of the PS2 reaction centre protein and the 33 kDa protein of the water splitting complex in sun and shade leaves, respectively.

Ameliorating effect of triacontanol on acidic mist-treated Erythrina variegata seedlings: Changes in growth and photosynthetic activities

Abstract In seedlings of the tropical tree species Erythrina variegata Lam. exposed to different acidic mist (H 2 SO 4 , pH 5.6, 4.0 and 2.0) for 7 days significant reduction in seedling growth (root and shoot length, leaf density, leaf area, fresh and dry mass accumulation) and photosynthetic activities were determined. In isolated thylakoid, a decrease in the activity of PS II and whole chain electron transport was observed at pH 4.0 and 2.0, but no significant transport was observed in PS I activity. When the seedlings were subsequently sprayed with TRIA, the acidic mist effect was partially or completely reversed indicating that TRIA can protect from acidic mist treatment. The artificial electron donors DPC and NH 2 OH markedly restored to the loss of PS II activity in acidic mist-treated leaves (pH 2.0). We believe that this is the first report of alleviating the acidic mists by TRIA.

Photoinhibition of photosynthesis in leaves of grapevine (Vitis vinifera L. cv. Riesling). Effect of chilling nights

Photoinhibition of photosynthesis was investigated in control (C) and chilling night (CN) leaves of grapevine under natural photoperiod at different sampling time in a day. The degree of photoinhibition was determined by means of the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) and photosynthetic electron transport measurements. When the potential efficiency of photosystem (PS) 2, Fv/Fm was measured at midday, it markedly declined with significant increase of F0 in CN leaves. In isolated thylakoids, the rate of whole chain and PS2 activity were markedly decreased in CN leaves than control leaves at midday. A smaller inhibition of PS1 activity was also observed in both leaf types. Later, the leaves reached maximum PS2 efficiencies similar to those observed in the morning during sampling at evening. The artificial exogenous electron donors diphenyl carbazide, NH2OH, and Mn2+ failed to restore the PS2 activity in both leaf types at midday. Thus CN enhanced inactivation on the acceptor side of PS2 in grapevine leaves. Quantification of the PS2 reaction centre protein D1 following midday exposure of leaves showed pronounced differences between C and CN leaves. The marked loss of PS2 activity in CN leaves noticed in midday samples was mainly due to the marked loss of D1 protein of the PS2 reaction centre.

Leaf plasticity to light intensity in Italian cypress (Cupressus sempervirens L.): adaptability of a Mediterranean conifer cultivated in the Alps.

Italian cypress (Cupressus sempervirens L.) is native to the eastern Mediterranean, an area characterised by hot, dry summers and mild winters. Over the centuries, however, the species has been introduced into more northerly regions, a long way from its native range. The current, generally warmer climatic conditions brought about by global warming have favoured its cultivation in even more northerly areas in the Alps and other European alpine regions. Given that not only temperature, but also light availability are limiting factors for the spread of cypress in these environments, it is important to ascertain how this species copes with low light conditions. The photosynthetic characteristics of cypress leaves collected from different portions of the crown with contrasting light availability were evaluated by several methods. Chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoid (Car) content was found to be higher in shade leaves than in sun leaves when measured on a fresh mass basis, although enzymatic activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) and nitrate reductase were lower in shade leaves. When the efficiency of PSII was measured by chlorophyll fluorescence, a marked reduction in F(m) was found in shade leaves, while F(o) remained unchanged. The use of exogenous electron donors diphenyl carbazide (DPC) and NH(2)OH actually improved the photosynthetic efficiency of shade leaves, and the same effect was found when PSII electron transport activity was measured as O(2) evolution. Altogether, these results seem to indicate lesser photosynthetic efficiency in shade leaves, probably an impairment on the donor side of the PSII. At the same time, analysis by SDS-PAGE revealed differences in the polypeptide composition of the thylakoid membranes of sun and shade leaves: the bands corresponding to 23 kDa, 28-25 kDa and 33 kDa polypeptides were less intense in the thylakoid membranes extracted from shade leaves. These results were further confirmed by an immunological study showing that the content of the 33 kDa protein, corresponding to the extrinsic PSII protein PsbO, was significantly diminished in shade leaves. The high plasticity of cypress leaves appears to be an advantageous trait in the plants response to variations in environmental conditions, including global change. Implications for the management of this Mediterranean species at the northern edge of its distribution are discussed.