Effects of Late Administration of Pentoxifylline and Tocotrienols in an Image-Guided Rat Model of Localized Heart Irradiation

Radiation-induced heart disease (RIHD) is a long-term side effect of radiotherapy of intrathoracic, chest wall and breast tumors when radiation fields encompass all or part of the heart. Previous studies have shown that pentoxifylline (PTX) in combination with α-tocopherol reduced manifestations of RIHD in rat models of local heart irradiation. The relative contribution of PTX and α-tocopherol to these beneficial effects are not known. This study examined the effects of PTX alone or in combination with tocotrienols, forms of vitamin E with potential potent radiation mitigation properties. Rats received localized X-irradiation of the heart with an image-guided irradiation technique. At 3 months after irradiation rats received oral treatment with vehicle, PTX, or PTX in combination with a tocotrienol-enriched formulation. At 6 months after irradiation, PTX-treated rats showed arrhythmia in 5 out of 14 animals. PTX alone or in combination with tocotrienols did not alter cardiac radiation fibrosis, left ventricular protein expression of the endothelial markers von Willebrand factor and neuregulin-1, or phosphorylation of the signal mediators Akt, Erk1/2, or PKCα. On the other hand, tocotrienols reduced cardiac numbers of mast cells and macrophages, but enhanced the expression of tissue factor. While this new rat model of localized heart irradiation does not support the use of PTX alone, the effects of tocotrienols on chronic manifestations of RIHD deserve further investigation.     

NO and ROS implications in the organization of root system architecture

Over the past decades the role of nitric oxide (NO) and reactive oxygen species (ROS) in signaling and cellular responses to stress has witnessed an exponential trend line. Despite advances in the subject, our knowledge of the role of NO and ROS as regulators of stress and plant growth and their implication in signaling pathways is still partial. The crosstalk between NO and ROS during root formation offers new domains to be explored, as it regulates several plant functions. Previous findings indicate that plants utilize these signaling molecules for regulating physiological responses and development. Depending upon cellular concentration, NO either can stimulate or impede root system architecture (RSA) by modulating enzymes through post-translational modifications. Similarly, the ROS signaling molecule network, in association with other hormonal signaling pathways, control the RSA. The spatial regulation of ROS controls cell growth and ROS determine primary root and act in concert with NO to promote lateral root primordia. NO and ROS are two central messenger molecules which act differentially to upregulate or downregulate the expression of genes pertaining to auxin synthesis and to the configuration of root architecture. The investigation concerning the contribution of donors and inhibitors of NO and ROS can further aid in deciphering their role in root development. With this background, this review provides comprehensive details about the effect and function of NO and ROS in the development of RSA.     

Growth and alkaloid production along with expression profiles of biosynthetic pathway genes in two contrasting morphotypes of prickly and prickleless Solanum viarum Dunal

Protoplasma - Growth and production kinetics of three important glycoalkaloids viz. α-solanine, solanidine, and solasodine in two contrasting prickly and prickleless plants of Solanum viarum...     

Ecdysteroid Stimulated Protein Synthesis in the Male Accessory Reproductive Glands of Spodoptera litura

Summary

20-hydroxyecdysone stimulates protein synthesis in the male accessory reproductive glands of pharate adults of Spodoptera litura both in vivo and in vitro. Juvenile hormone-I has no synergistic effect when given in conjunction with ecdysone in vivo but it inhibits ecdysone-stimulated protein synthesis in vitro.     

Re-expression of proteins involved in cytokinesis during cardiac hypertrophy

Cardiomyocytes stop dividing after birth and postnatal heart growth is only achieved by increase in cell volume. In some species, cardiomyocytes undergo an additional incomplete mitosis in the first postnatal week, where karyokinesis takes place in the absence of cytokinesis, leading to binucleation. Proteins that regulate the formation of the actomyosin ring are known to be important for cytokinesis. Here we demonstrate for the first time that small GTPases like RhoA along with their downstream effectors like ROCK I, ROCK II and Citron Kinase show a developmental stage specific expression in heart, with high levels being expressed in cardiomyocytes only at stages when cytokinesis still occurs (i.e. embryonic and perinatal). This suggests that downregulation of many regulatory and cytoskeletal components involved in the formation of the actomyosin ring may be responsible for the uncoupling of cytokinesis from karyokinesis in rodent cardiomyocytes after birth. Interestingly, when the myocardium tries to adapt to the increased workload during pathological hypertrophy a re-expression of proteins involved in DNA synthesis and cytokinesis can be detected. Nevertheless, the adult cardiomyocytes do not appear to divide despite this upregulation of the cytokinetic machinery. The inability to undergo complete division could be due to the presence of stable, highly ordered and functional sarcomeres in the adult myocardium or could be because of the inefficiency of degradation pathways, which facilitate the division of differentiated embryonic cardiomyocytes by disintegrating myofibrils.     

Melanocyte–keratinocyte interaction induces calcium signalling and melanin transfer to keratinocytes

Physical contact between melanocytes and keratinocytes is a prerequisite for melanosome transfer to occur, but cellular signals induced during or after contact are not fully understood. Herein, it is shown that interactions between melanocyte and keratinocyte plasma membranes induced a transient intracellular calcium signal in keratinocytes that was required for pigment transfer. This intracellular calcium signal occurred due to release of calcium from intracellular stores. Pigment transfer observed in melanocyte–keratinocyte co‐cultures was inhibited when intracellular calcium in keratinocytes was chelated. We propose that a ‘ligand‐receptor’ type interaction exists between melanocytes and keratinocytes that triggers intracellular calcium signalling in keratinocytes and mediates melanin transfer.     

In vitro culture in combination with aeroponics is an efficient means of mass propagation of Sarcostemma acidum: a rare medicinal plant of Indian arid zone

In Vitro Cellular & Developmental Biology - Plant - In vitro culture in combination with aeroponics is observed to be an efficient means for mass propagation of Sarcostemma acidum in the...