Mechanisms of Cellular Senescence: Cell Cycle Arrest and Senescence Associated Secretory Phenotype

Cellular senescence is a stable cell cycle arrest that can be triggered in normal cells in response to various intrinsic and extrinsic stimuli, as well as developmental signals. Senescence is considered to be a highly dynamic, multi-step process, during which the properties of senescent cells continuously evolve and diversify in a context dependent manner. It is associated with multiple cellular and molecular changes and distinct phenotypic alterations, including a stable proliferation arrest unresponsive to mitogenic stimuli. Senescent cells remain viable, have alterations in metabolic activity and undergo dramatic changes in gene expression and develop a complex senescence-associated secretory phenotype. Cellular senescence can compromise tissue repair and regeneration, thereby contributing toward aging. Removal of senescent cells can attenuate age-related tissue dysfunction and extend health span. Senescence can also act as a potent anti-tumor mechanism, by preventing proliferation of potentially cancerous cells. It is a cellular program which acts as a double-edged sword, with both beneficial and detrimental effects on the health of the organism, and considered to be an example of evolutionary antagonistic pleiotropy. Activation of the p53/p21WAF1/CIP1 and p16INK4A/pRB tumor suppressor pathways play a central role in regulating senescence. Several other pathways have recently been implicated in mediating senescence and the senescent phenotype. Herein we review the molecular mechanisms that underlie cellular senescence and the senescence associated growth arrest with a particular focus on why cells stop dividing, the stability of the growth arrest, the hypersecretory phenotype and how the different pathways are all integrated

Inventaire et distribution spatio-temporelle des macroinvertébrés bioindicateurs de trois plans d’eau du bassin de la Volta au Burkina Faso

Une étude des macroinvertébrés dans deux lacs de barrages hydro- agricoles (Bama et de Boura) et dans le lac naturel de Bala a permis de mettre en évidence la distribution spatio-temporelle des macroinvertébrésbioindicateurs de la qualité des eaux. La collecte des échantillons a été inspirée de la méthode conventionnelle de la Directive Cadre sur l’Eau de l’Union Européenne (DCE). L’étude a permis d’identifier 26405 individusde macroinvertébrés répartis en 71 espèces et 33 familles au total sur les trois sites de Bama (25 familles), Boura (23 familles) et Bala (30 familles). Les polluo-sensibles ont été décrites au lac naturel de Bala : des crustacés de l’ordre des Cladocères et 7 familles d’insectes (Gyrinidés, Pleidés, Baetidés Ephémérélidés, Tabanidés, Cératopogonidés et Canaceidés). L’étude a noté la présence de l’espèce Hydrocanthus ferruginicollis (Notéridés) particulièrement dominante dans les retenues hydro-agricoles de Bama (30,52% des Coléoptères) et Boura (27,32% des Coléoptères) ; tandis qu’elle ne représente que 7,51% des Coléoptères récoltés dans le lac naturel de Bala. Cette étude considère que les polluo-sensibles et les polluo-résitants décrits respectivement à Bala et à Bama et Boura peuvent être considérés comme de potentiels bioindicateurs des plans d’eau du bassin de la Volta.Mots clés : Macroinvertébrés, distribution, bioindicateurs, petits plans d’eau, bassin de la Volta, Burkina Faso

A biogenic amine and a neuropeptide act identically: tyramine signals through calcium in drosophila tubule stellate cells

Insect osmoregulation is subject to highly sophisticated endocrine control. In Drosophila, both Drosophila kinin and tyramine act on the Malpighian (renal) tubule stellate cell to activate chloride shunt conductance, and so increase the fluid production rate. Drosophila kinin is known to act through intracellular calcium, but the mode of action of tyramine is not known. Here, we used a transgenically encoded GFP::apoaequorin translational fusion, targeted to either principal or stellate cells under GAL4/UAS control, to demonstrate that tyramine indeed acts to raise calcium in stellate, but not principal cells. Furthermore, the EC(50) tyramine concentration for half-maximal activation of the intracellular calcium signal is the same as that calculated from previously published data on tyramine-induced increase in chloride flux. In addition, tyramine signalling to calcium is markedly reduced in mutants of NorpA (a phospholipase C) and itpr, the inositol trisphosphate receptor gene, which we have previously shown to be necessary for Drosophila kinin signalling. Therefore, tyramine and Drosophila kinin signals converge on phospholipase C, and thence on intracellular calcium; and both act to increase chloride shunt conductance by signalling through itpr. To test this model, we co-applied tyramine and Drosophila kinin, and showed that the calcium signals were neither additive nor synergistic. The two signalling pathways thus represent parallel, independent mechanisms for distinct tissues (nervous and epithelial) to control the same aspect of renal function

Greenhouse cultivation of fruit crops with special reference to India: An overview

India is facing various challenges in fruit cultivation viz., climate change, increasing pressure on natural resources, decreasing land tenure with the ever-increasing population. Besides this, the demand for quality fruit is also on the rise as people are now more aware of a nutritious and healthy diet. The quality with higher production is difficult with the traditional system of cultivation and requires a more scientific approach in cultivation. Greenhouse cultivation technology can enhance quality and quantity both. This technology is required to convert some portion of the present 6.5 million ha of the fruit-growing area to increase national productivity and product quality. The purpose of greenhouse cultivation is to grow crops by altering the micro-environment surrounding the crop so that the plant performs maximum to its genetic potential. It also increases the yield, improves the quality and stability of production and makes commodities available when there is no outdoor production. China is the world leader in greenhouse fruit production with the largest area under this technology. In India, greenhouse fruit cultivation is in its infancy as the only strawberry is commercially being grown under greenhouses. However, in fluctuating environmental conditions and losses in fruit crops due to various biotic and abiotic stresses, protecting the fruit crops for the off-season, quality and higher production will be a necessity in future. Keeping in view the low productivity of fruit crops in India and future needs of round the year quality production, an overview of work and cultivation scenario on this aspect is discussed in this paper

Low-cost quantification of greenhouse gas emissions in smallholder agro-ecosystem: a comparative analysis of methods

Quantification of greenhouse gas (GHG) exchanges between agricultural field and the atmosphere is essential for understanding the contribution of various production systems to the total emissions, develop mitigation options and policies, raise awareness and encourage adoption. But, GHG quantification from smallholder agricultural landscape is challenging primarily because of the heterogeneity of production systems. Various methods have been developed over years to quantify GHG fluxes between agricultural ecosystem and atmosphere. In this paper, we reviewed and analysed the common methods with regard to their scale and precision of quantification, cost effectiveness, prospects and limitations focusing mainly on smallholder production systems. As most of the quantification methods depend on ground data and due to data deficit for smallholder systems, field measurement must be an essential part of GHG emission inventories under such systems. Chamber-based method is a principal approach for field level quantification under smallholder production system mainly because of its cost effectiveness, portability and adoptability under diverse field conditions. However, direct measurement of GHG for all mosaics of smallholder production landscape is impractical and therefore use of models becomes imperative. Here, selection of suitable models and their rigorous parameterization, calibration and validation under various production environments are necessary in order to obtain meaningful emission estimation. After proper validation, linking dynamic ecosystem models to geographic information system (GIS) helps estimating GHG emission within reasonable time and cost. Integration of different approaches such as chamber-based measurement to generate field data, simulation modelling by using empirical as well as process-based models coupled with use of satellite imagery may provide a robust estimate of GHGs emission than use of a single approach

Climate Smart agricultural practices improve soil quality through organic carbon enrichment and lower greenhouse gas emissions in farms of bread bowl of India

Acknowledgements The authors are thankful to NEWS India-UK for providing the first author Fellowship during the study. We are also grateful to CCAFS-CIMMYT for allowing us to collect soil samples from climate smart villages of Karnal, Haryana. The help received from Kartar Singh during soil analysis, and Kapil, Rakesh, Rajinder and Anil during field survey and sample collection is gratefully acknowledged. We are grateful to two anonymous reviewers for their insightful comments which significantly improved the quality of the manuscript.Peer reviewedPostprin

Effect of potassium and zinc fertilizer on crop yield, nutrient uptake and distribution of potassium and zinc fractions in Typic Ustipsamment

A field experiment was conducted to study the effect of potassium and zinc fertilizer on status and content of potassium and zinc fractions and their effect on crop yield, nutrient uptake and nutrient availability in the soil. Significant increase in grain yield, straw yield, K uptake, and different K fractions in the soil (exchangeable K, water soluble K, Morgan’s extractable K, lattice K and total K in the soil) were recorded with increase in K levels from 0 to 60 kg K/ha. Zinc fertilization in wheat also significantly increased crop yield and Zn uptake but interaction between K and Zn was not found to be significant in respect of yield, uptake, and various K and Zn fractions. Water-soluble K showed significant and positive correlation with exchangeable K (r= 0.928), Morgan’s extractable K (r= 0.983) and lattice K (r= 0.969), indicating rapid equilibrium establishment between these forms. Step wise regression analysis using different pools of K revealed the importance of water soluble K and lattice K influencing crop yield, K uptake by wheat. Similarly, application of 9 kg Zn/ha increased the Zn fractions present in soil and correlation data indicated that these fractions are in a state of dynamic equilibrium with each other. In the present study, DTPA-Zn accounted for 65% and 70% of the variation in grain yield and Zn uptake by wheat, indicating that DTPA-Zn was efficient in providing Zn nutrition to wheat

Central nervous system tumors: a histopathological study

Background: Brain tumors can originate in almost any type of tissue, cell or mixture of cell types in the brain or spinal cord. Tumors in different areas of the central nervous system may be treated differently and have a different prognosis.Methods: In the period between 2011-2015, we studied on 59 patients diagnosed with CNS tumors according to the World Health Organization’s diagnostic criteria. Patient data were retrieved from the archives of the department of Pathology, Sardar Patel Medical College, Bikaner. The diagnosis in all the cases were made on hematoxylin & eosin stained slides of processed tissue.Results: Patients ages ranged from 3.5-65 years with a mean age of 41.2 years and a male to female ratio of 1.8:1. Majority of tumors had intracranial location (55 cases, 93.23%). 91.5% tumors were solid in consistency. Frontal lobe (37.3%) was the predominant affected region. Most tumors were originated from neuroepithelium (67.8%) followed by meninges (22.03%). When examining the data pertaining to specific types of tumors, most frequent type of CNS tumors was astrocytoma (31 cases, 52.5%), followed by meningioma (13 cases, 22%).Conclusion: The most frequent type of CNS tumours in this study was astrocytoma, followed by meningioma. Males are at much higher risk of developing CNS tumour in comparison to females (1.8:1). WHO Grade IV lesions were more common in our institutional set up. The exact histological diagnosis of CNS tumors is essential to predict the prognostic factors.

A study of the correlation of serum vitamin D levels to Child-Pugh and MELD-Na scoring system in cirrhosis of the liver

Background: Vitamin D is a hormone with known effect on calcium homeostasis, but recently there is increasing recognition that it also is involved in cell proliferation and differentiation, has immunomodulatory and anti-inflammatory properties. These effect may explain its importance in the liver diseases. Vitamin D deficiency has been reported highly prevalent in Chronic liver disease (CLD) and there is an emerging interest to explore the relationship of vitamin D deficiency and severity of CLD. The aim of the study was to evaluate the correlation of serum vitamin D levels to the Child Pugh and MELD-Na scoring system in liver cirrhosis and to establish its relationship with the severity of the disease.Methods: Serum vitamin D levels were measured in 100 patients of CLD and 100 healthy controls. The degree of liver dysfunction was estimated by Child-Pugh and MELD-Na scores.Results: 91% of the CLD patients had subnormal vitamin-D levels. The mean vitamin D level in CLD patients was lower (15.97±7.45) than controls (30.12±6.60) with statistical significance (p= 0.0001). On linear regression vitamin D level showed significant negative correlation with Child Pugh score (r= –0.446, p<0.001) and MELD score (r= –0.395, p<0.001). Low vitamin D level was associated with poor outcome (mean vitamin D level 9.61±3.01 who died versus 16.52±7.47 who survived and discharged).Conclusions: CLD is associated with a significantly low level of vitamin D. The lower level of vitamin D is associated with severity of CLD, mortality and increased risk for complications. Awareness of serum vitamin D level in CLD patients is important to improve outcome

Floral biology studies of Egyptian clover, Trifolium alexandrinum L.

Floral biology studies of Egyptian clover, Trifolium alexandrinum was studied at Forage Section, Department of Genetics and Plant Breeding, CCS, Haryana Agricultural University, Hisar during 2012 and 2013. T. alexandrinum flower head of cultivar HB-2 consisted of numerous yellowish-white flowers that measured 22.7+1.3 mm in length and consists of a mean of 70.5+1.70 florets. The mean length of a floret, sepals, petals and stamen were 12.3±1.9, 4.4+0.6, 4.1+2.2 and 3.4+0.5 mm, respectively.  On an average a floret, remained in bud stage (A+B+C) for a longer period of 80.4+1.2 hours during 2012 than in 2013 (69.7+7.7 h). The overall mean duration of bud stage A (petals concealed in bud) was the longest (35.6+5.4 h) as compared to stage B when petals became visible but not expended (26.2+3.0 h) and C (24.8+2.0 h) when petals expended but anthers were not visible. The bud stage (A+B+C) lasted for a mean duration of 75.1+3.9 hours. The overall mean duration of the anthesis stage (D1+D2) was 63.1+5.6 hours (range 45-87 hours) and that of post anthesis at 37.8+6.9 (range 30-51) hours. The life cycle of T. alexandrinum flowers on an average was completed in 186.8±7.0 hours