Differential expression of microRNAs and potential targets under drought stress in barley

Drought is a crucial environmental constraint limiting crop production in many parts of the world. microRNA (miRNA) based gene regulation has been shown to act in several pathways, including crop response to drought stress. Sequence based profiling and computational analysis have revealed hundreds of miRNAs and their potential targets in different plant species under various stress conditions, but few have been biologically verified. In this study, eleven candidate miRNAs were tested for their expression profiles in barley. Differences in accumulation of only four miRNAs (Ath-miR169b, Osa-miR1432, Hv-miRx5 and Hv-miR166b/c) were observed between drought-treated and well-watered barley in four genotypes. miRNA targets were predicted using degradome analysis of two, different genotypes and genotype-specific target cleavage was observed. Inverse correlation of mature miRNA accumulation with miRNA target transcripts was also genotype-dependent under drought treatment. Drought-responsive miRNAs accumulated predominantly in mesophyll tissues. Our results demonstrate genotype-specific miRNA regulation under drought stress and evidence for their role in mediating expression of target genes for abiotic stress response in barley.Jannatul Ferdous, Juan Carlos Sanchez-Ferrero, Peter Langridge, Linda Milne, Jamil Chowdhury, Chris Brien, and Penny J. Tricke

Neo-Newtonian cosmology: An intermediate step towards General Relativity

Cosmology is a field of physics in which the use of General Relativity theory is indispensable. However, a cosmology based on Newtonian gravity theory for gravity is possible in certain circumstances. The applicability of Newtonian theory can be substantially extended if it is modified in such way that pressure has a more active role as source of the gravitational field. This was done in the neo-Newtonian cosmology. The limitation on the construction of a Newtonian cosmology, and the need for a relativistic theory in cosmology are reviewed. The neo-Newtonian proposal is presented, and its consequences for cosmology are discussed.Comment: 10 pages. Portuguese version submitted to RBE

Mechanical vibrations of pendant liquid droplets

A simple optical deflection technique was used to monitor the vibrations of microlitre pendant droplets of deuterium oxide, formamide, and 1,1,2,2-tetrabromoethane. Droplets of different volumes of each liquid were suspended from the end of a microlitre pipette and vibrated using a small puff of nitrogen gas. A laser was passed through the droplets and the scattered light was collected using a photodiode. Vibration of the droplets resulted in the motion of the scattered beam and time-dependent intensity variations were recorded using the photodiode. These time- dependent variations were Fourier transformed and the frequencies and widths of the mechanical droplet resonances were extracted. A simple model of vibrations in pendant/sessile drops was used to relate these parameters to the surface tension, density and viscosity of the liquid droplets. The surface tension values obtained from this method were found to be in good agreement with results obtained using the standard pendant drop technique. Damping of capillary waves on pendant drops was shown to be similar to that observed for deep liquid baths and the kinematic viscosities obtained were in agreement with literature values for all three liquids studied

Classification of Supernovae

The current classification scheme for supernovae is presented. The main observational features of the supernova types are described and the physical implications briefly addressed. Differences between the homogeneous thermonuclear type Ia and similarities among the heterogeneous core collapse type Ib, Ic and II are highlighted. Transforming type IIb, narrow line type IIn, supernovae associated with GRBs and few peculiar objects are also discussed.Comment: 16 Pages, 4 figures, to be published in "Supernovae and Gamma-Ray Bursters," ed. Kurt W. Weile

Optical Light Curves of Supernovae

Photometry is the most easily acquired information about supernovae. The light curves constructed from regular imaging provide signatures not only for the energy input, the radiation escape, the local environment and the progenitor stars, but also for the intervening dust. They are the main tool for the use of supernovae as distance indicators through the determination of the luminosity. The light curve of SN 1987A still is the richest and longest observed example for a core-collapse supernova. Despite the peculiar nature of this object, as explosion of a blue supergiant, it displayed all the characteristics of Type II supernovae. The light curves of Type Ib/c supernovae are more homogeneous, but still display the signatures of explosions in massive stars, among them early interaction with their circumstellar material. Wrinkles in the near-uniform appearance of thermonuclear (Type Ia) supernovae have emerged during the past decade. Subtle differences have been observed especially at near-infrared wavelengths. Interestingly, the light curve shapes appear to correlate with a variety of other characteristics of these supernovae. The construction of bolometric light curves provides the most direct link to theoretical predictions and can yield sorely needed constraints for the models. First steps in this direction have been already made.Comment: To be published in:"Supernovae and Gamma Ray Bursters", Lecture Notes in Physics (http://link.springer.de/series/lnpp

Fine-Scale Mapping of the 5q11.2 Breast Cancer Locus Reveals at Least Three Independent Risk Variants Regulating MAP3K1

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