Evolution of the third eye: a phylogenetic comparative study of parietal‐eye size as an ecophysiological adaptation in Liolaemus lizards

The parietal, or third, eye is a photosensory organ situated in the middle of the skull of many lizards. Despite many hypotheses, its exact ecological functions are still unclear. Studies have compared the presence and absence of a functioning parietal eye, although there are no quantitative studies of parietal‐eye traits in relation to ecology, physiology or behaviour. In the present study, we report the first comparative study of relative parietal‐eye size in relation to climatic and thermophysiological variables. We studied thirty species of Liolaemus, a genus of South‐American lizards inhabiting a range of climatic conditions, but found little evidence for adaptation to thermal environment, in that parietal‐eye size did not vary meaningfully with latitude, altitude or any measures of environmental temperature. Neither did it relate to thermophysiology; there was a weak relation to thermal tolerance, although this was partially confounded with body size, which explained 23% of the among‐species variance after controlling for within‐species variation. The negative results obtained could not be explained by phylogenetic constraints because we found no evidence of phylogenetic inertia. We also observed high intraspecific variation indicating that parietal‐eye size may not be under strong selection for accuracy. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 870–883.     

Bats respond to polarity of a magnetic field

Bats have been shown to use information from the Earth's magnetic field during orientation. However, the mechanism underlying this ability remains unknown. In this study we investigated whether bats possess a polarity- or inclination-based compass that could be used in orientation. We monitored the hanging position of adult Nyctalus plancyi in the laboratory in the presence of an induced magnetic field of twice Earth-strength. When under the influence of a normally aligned induced field the bats showed a significant preference for hanging at the northern end of their roosting basket. When the vertical component of the field was reversed, the bats remained at the northern end of the basket. However, when the horizontal component of the field was reversed, the bats changed their positions and hung at the southern end of the basket. Based on these results, we conclude that N. plancyi, unlike all other non-mammalian vertebrates tested to date, uses a polarity-based compass during orientation in the roost, and that the same compass is also likely to underlie bats' long-distance navigation abilities.     

CHIH-DFT determination of the molecular structure infrared spectra,UV spectra and chemical reactivity of three antitubercular compounds: Rifampicin,Isoniazid and Pyrazinamide

Three of the most frequent antitubercular agents employed against Mycobacterium tuberculosis are: Rifampicin, Isoniazid and Pyrazinamide. It has been proven that the use of these antitubercular agents together, shortens the treatment period from 12–18 months to 6 months [1]. In this work we use a new Density Functional Theory chemistry model called CHIH-DFT (Chihuahua-Heterocycles-Density Functional Theory) that reflects the mixture of Hartree Fock exchange and DFT exchange, according to a mixing parameter based on empirical rules suited for heterocyclic systems. This new chemistry model was used to calculate the molecular structure of these antitubercular compounds, as well as their infrared, UV spectra, chemical reactivity and electronic properties. The UV and infrared spectra were obtained by experimental techniques. The calculated molecular structure, UV and IR spectra values from CHIH-DFT were compared with experimentally obtained values and theoretical studies. These results are in good agreement with experimental and theoretical studies. We also predicted using the relative electrophilicity and relative nucleophilicity concepts as defined by Roy et al. [2] the chemical active sites for the three antitubercular compounds as well as their electronegativity, ionization potential, electron affinity, hardness, dipole moment, E_HOMO-E_LUMO gap energy, etc.      

Frontiers of biomedical text mining: current progress

It is now almost 15 years since the publication of the first paper on text mining in the genomics domain, and decades since the first paper on text mining in the medical domain. Enormous progress has been made in the areas of information retrieval, evaluation methodologies and resource construction. Some problems, such as abbreviation-handling, can essentially be considered solved problems, and others, such as identification of gene mentions in text, seem likely to be solved soon. However, a number of problems at the frontiers of biomedical text mining continue to present interesting challenges and opportunities for great improvements and interesting research. In this article we review the current state of the art in biomedical text mining or 'BioNLP' in general, focusing primarily on papers published within the past year.     

Raman,FT-IR spectroscopic analysis and first-order hyperpolarisability of 3-benzoyl-5-chlorouracil by first principles

3-Benzoyl-5-chlorouracil (3B5CU), a biologically active synthetic molecule, has been analysed at DFT/6-311+ + G(d,p) level and reported for the first time as a potential candidate for nonlinear optical (NLO) applications. The optimised skeleton of 3B5CU molecule is non-planar. The frontier orbital energy gap, dipole moment, polarisability and first static hyperpolarisability have been calculated. The first static hyperpolarisability is found to be almost 15 times higher than that of urea. The high value of first static hyperpolarisability (2.930 × 10^? 30 e.s.u.) due to the intra-molecular charge transfer in 3B5CU has been discussed using first principles. A complete vibrational analysis of the molecule has been performed by combining the experimental Raman, FT-IR spectral data and the quantum chemical calculations. In general, a good agreement of calculated modes with the experimental ones has been obtained. The strong vibrational modes contributing towards NLO activity, involving the whole charge transfer path, have been identified and analysed.     

Binocular fusion in Panum’s limiting case of stereopsis obeys the uniqueness constraint

In the information processing procedure of stereo vision, the uniqueness constraint has been used as one of the constraints to solve the “correspondence problem”. While the uniqueness constraint is valid in most cases, whether it is still valid in some particular stimulus configuration (such as Panum’s limiting case) has been a problem of widespread debate for a long time. To investigate the problem, we adopted the Panum’s limiting case as its basic stimulus configuration, and delved into the phenomenon of binocular fusion from two distinct aspects: visual direction and orientation disparity. The results show that in Panum’s limiting case binocular fusion does not comply with the rules governing regular binocular fusion as far as visual direction and orientation disparity are concerned. This indicates that double fusion does not happen in Panum’s limiting case and that the uniqueness constraint is still valid.     

Cowpea weevil flights to a point source of female sex pheromone: analyses of flight tracks at three wind speeds

Abstract.  Two-day-old male cowpea weevils, Callosobruchus maculatus, fly upwind to a point source of female sex pheromone at three wind speeds. All beetles initiating flight along the pheromone plume make contact with the pheromone source. Analysis of digitized flight tracks indicates that C. maculatus males respond similarly to moths tested at several wind speeds. Beetles' mean net upwind speeds and speeds along their track are similar ( P  > 0.05) across wind speeds, whereas airspeeds increase ( P <  0.01) with increasing wind speed. Beetles adjust their course angles to fly more directly upwind in higher wind speeds, whereas track angles are almost identical at each wind speed. The zigzag flight paths are generally narrow compared with most moth flight tracks and interturn distances are similar ( P  > 0.05) at the wind speeds employed. The frequency of these counterturns across the wind line is almost constant regardless of wind speed, and there is little variation between individuals. The upwind flight tracks are more directly upwind than those typically seen for male moths flying upwind toward sex pheromone sources. Male moths typically produce a bimodal distribution of track angles to the left and right of the windline, whereas C. maculatus males' track angles are centred about 0°. Preliminary examination of two other beetle species indicates that they fly upwind in a similar fashion.     

PHOTOSYNTHETIC CHARACTERIZATION OF DEVELOPING AND MATURE AKINETES OF APHANIZOMENON OVALISPORUM (CYANOPROKARYOTA)1

Akinetes, differentiated resting cells produced by many species of filamentous, heterocystous cyanobacteria, enable the organism to survive adverse conditions, such as cold winters and dry seasons, and to maintain germination capabilities until the onset of suitable conditions for vegetative growth. Mature akinetes maintain a limited level of metabolic activities, including photosynthesis. In the present study, we have characterized changes in the photosynthetic apparatus of vegetative cells and akinetes of the cyanobacterium Aphanizomenon ovalisporum Forti (Nostocales) during their development and maturation. Photosynthetic variable fluorescence was measured by microscope‐PAM (pulse‐amplitude‐modulated) fluorometry, and the fundamental composition of the photosynthetic apparatus was evaluated by fluorescence and immunological techniques. Vegetative cells and akinetes from samples of Aphanizomenon trichomes from akinete‐induced cultures at various ages demonstrated a gradual reduction, with age, in the maximal photosynthetic quantum yield in both cell types. However, the maximal quantum yield of akinetes declined slightly faster than that of their adjacent vegetative cells. Mature akinetes isolated from 6‐ to 8‐week‐old akinete‐induced cultures maintained only residual photosynthetic activity, as indicated by very low values of maximal photosynthetic quantum yields. Based on 77 K fluorescence emission data and immunodetection of PSI and PSII polypeptides, we concluded that the ratio of PSI to PSII reaction centers in mature akinetes is slightly higher than the ratio estimated for exponentially grown vegetative cells. Furthermore, the cellular abundance of these protein complexes substantially increased in akinetes relative to exponentially grown vegetative cells, presumably due to considerable increase in the biovolume of akinetes.     

Density functional theory,restricted Hartree–Fock simulations and vibrational spectroscopic studies of nicorandil

Fourier transform infrared and Raman spectra of nicorandil have been recorded. The structure, conformational stability, geometry optimisation and vibrational frequencies have been investigated. Complete vibrational assignments were made for the stable conformer of the molecule using restricted Hartree–Fock (RHF) and density functional theory (DFT) calculations (B3LYP) with the 6-31G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of the molecule and calculated results by RHF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. Natural bond order analysis of the title molecule was also carried out. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibration modes.     

ANS fluorescence: Potential to discriminate hydrophobic sites of proteins in solid states

In the current study, ANS fluorescence was established as a powerful tool to study proteins in solid-state. Silk fibroin from Bombyx mori cocoons was used as a paradigm protein. ANS incorporated into the films of silk fibroin exhibits fluorescence with two-lifetime components that can be assigned to the patches and/or cavities with distinct hydrophobicities. Decay associated spectra (DAS) of ANS fluorescence from both sites could be fit to the single log-normal component indicating their homogeneity. ANS binding sites in the protein film are specific and could be saturated by ANS titration. ANS located in the binding site that exhibits the long-lifetime fluorescence is not accessible to the water molecules and its DAS stays homogeneously broadened upon hydration of the protein film. In contrast, ANS from the sites demonstrating the short-lifetime fluorescence is accessible to water molecules. In the hydrated films, solvent-induced fluctuations produce an ensemble of binding sites with similar characters. Therefore, upon hydration, the short-lifetime DAS becomes significantly red-shifted and inhomogeneously broadened. The similar spectral features have previously been observed for ANS complexed with globular proteins in solution. The data reveal the origin of the short-lifetime fluorescence component of ANS bound to the globular proteins in aqueous solution. Findings from this study indicate that ANS is applicable to characterize dehydrated as well as hydrated protein aggregates, amyloids relevant to amyloid diseases, such as Alzheimer's, Parkinson, and prion diseases.