The Effects of Landscape and Experience on the Navigation and Foraging Behaviour of Bumblebees, Bombus terrestris

Bumblebees live in an environment where the spatial distribution of foraging resources is always changing. In order to keep track of such changes, bumblebees employ a variety of different navigation and foraging strategies. Although a substantial amount of research has investigated the different navigation and foraging behaviours of bumblebees, much less is known of the effects that landscape features have on bumblebee behaviour. In this thesis, a series of experiments were conducted in order to investigate the role that landscape features have on the navigation and foraging behaviour of Bombus terrestris and whether individuals’ experience influences such behaviour. A hedgerow situated next to the colony was not found to significantly shape the flight paths or foraging choices of naïve bumblebees. Homing success was investigated and used as a proxy for foraging range in different environment types. Both the release distance and the type of environment were found to have a significant effect on the homing success of Bombus terrestris workers. Previous experience of the landscape was also found to significantly affect the time it took bumblebees to return to the colony (homing duration) as well as the likelihood of staying out overnight before returning to the colony. When focusing on the first five flights of a naïve bumblebee worker, experience was not found to significantly affect flight duration. Experience, however, significantly affected the weight of pollen foraged. The observed behaviour of bumblebee gynes provisioning their maternal colony with pollen was also investigated. The influx of pollen into the colony was found to affect this behaviour, suggesting that gynes will provision the maternal colony in response to its nutritional needs. The overall results are also discussed within the context of informing landscape management practices. The results presented in this thesis point to the critical role that factors such as the physical landscape and individual experience play in influencing bumblebee behaviour.South Devon Area of Outstanding Natural Beauty (AONB) Uni

Effects of distribution of excitation energy transfer times and protein dynamics on spectral hole burning in pigment-protein complexes involved in photosynthesis

Understanding the spectral properties of natural photosynthetic complexes (the excited state lifetimes, electron-phonon couplings, distributions of “solvent shifts” of various pigments, and the interactions between them (manifestations of excitonic effects, excitation energy transfer, charge transfer) as well as pigments site energies, lowest-energy states and origin of various emission bands) is fundamental to advance the design of the artificial photosynthetic systems. Traditionally the spectral properties of natural photosynthetic complexes are explored by either time-domain or frequency-domain high-resolution spectroscopy methods, including non-photochemical spectral hole burning (NPHB). The main goal of this thesis was the study of various effects of the distribution of excitation energy transfer times and protein dynamics on non-photochemical hole burning processes in photosynthetic pigment-protein complexes. In the first part of this thesis we present our results concerning the inclusion of the distributions of excitation energy transfer (EET) rates (homogeneous line widths) and charge separation rates into treatment of the resonant and non-resonant NPHB processes in photosynthetic chlorophyll-protein complexes. Thus, the effects of the line width distributions resulting from Förster-type EET between weakly interacting pigments with uncorrelated site distribution functions, on the resonant NPHB process have been explored both theoretically and experimentally in isolated CP43 antenna from spinach. Furthermore, we have also demonstrated that inclusion of the effects of frequency-dependent EET rate distributions and burning following EET on the treatment of non-resonant NPHB spectra of trimeric Fenna-Matthews-Olson protein from Chlorobium tepidum leads to reasonable agreement between the theoretical and experimental data. The second part of this thesis is focused on the analysis of HB spectral properties of the lowest energy states of Photosystem I (PSI) with the aims to gain better understanding of particular structural origins of these states as well as on the protein dynamics of PSI. We explored the satellite hole structures obtained after illumination at various wavelengths and the dependence of those structures on thermocycling. In order to explore the protein dynamics in PSI SHB experiments and compare it with SPCS observations special attention was devoted to the study of the influence of the P700 redox state on resonant and nonresonant NPHB spectra from cyanobacteria Thermosynechococcus elongatus

Optical spectroscopy of photosynthetic complexes : focus on low-temperature protein dynamics

To perform photosynthesis, plants, algae and bacteria possess well organized and closely coupled photosynthetic pigment-protein complexes. The information on energy transfer processes and protein dynamics contained in the narrow zero-phonon lines at low temperatures is hidden under the inhomogeneous broadening. Thus, it is difficult to analyze the spectroscopic properties of these complexes in sufficient detail by conventional spectroscopy methods. In this context, high resolution spectroscopy techniques such as Spectral Hole Burning, Fluorescence Line Narrowing and Single Molecule / Single Complex Spectroscopy are powerful tools designed to overcome the inhomogeneous broadening difficulty. This thesis focuses mainly on the low-temperature protein dynamics of several photosynthetic protein complexes (LH2, CP43, CP29 and LHCII). The hole growth kinetics and the shape of the anti-hole due to the non-photochemical spectral hole burning have been explored, and interpreted within the framework of theoretical models describing spectral diffusion due to conformational changes between nearly identical substates on a multi-tier protein energy landscapes

Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

44 Pag., 2 Tabl. The definitive version is available at: http://pubs.acs.org/journal/jpcbfkThe parameters of barrier distributions on the protein energy landscape in the excited electronic state of the pigment/protein system have been determined by means of spectral hole burning for the lowest-energy pigments of CP43 core antenna complex and CP29 minor antenna complex of spinach Photosystem II (PS II) as well as of trimeric and monomeric LHCII complexes transiently associated with the pea Photosystem I (PS I) pool. All of these complexes exhibit sixty to several hundred times lower spectral hole burning yields as compared with molecular glassy solids previously probed by means of the hole growth kinetics measurements. Therefore, the entities (groups of atoms), which participate in conformational changes in protein, appear to be significantly larger and heavier than those in molecular glasses. No evidence of a small (1 cm−1) spectral shift tier of the spectral diffusion dynamics has been observed. Therefore, our data most likely reflect the true barrier distributions of the intact protein and not those related to the interface or surrounding host. Possible applications of the barrier distributions as well as the assignments of low-energy states of CP29 and LHCII are discussed in light of the above results.Research at Concordia University is supported by NSERC and CFI. R.P. would like to thank Spanish MICINN (grant AGL2008-00377). M.S. acknowledges the contribution of the Photosynthetic Systems Program, Chemical Sciences, Geosciences, and Biosciences Division, Basic Energy Sciences, USDOE. J.P. and K.-D.I. gratefully acknowledge support from Deutsche Forschungsgemeinschaft (SFB 429, TP A1, and TP A3, respectively).Peer reviewe

Conformational changes in pigment-protein complexes at low temperatures - spectral memory and a possibility of cooperative effects

40 Pags.- 9 Figs. The definitive version is available at: http://pubs.acs.org/journal/jpcbfkWe employed non-photochemical hole burning (NPHB) and fluorescence line narrowing (FLN) spectroscopies to explore protein energy landscapes and energy transfer processes in dimeric cytochrome b6f, containing one chlorophyll molecule per protein monomer. The parameters of the energy landscape barrier distributions quantitatively agree with those reported for other pigment-protein complexes involved in photosynthesis. Qualitatively, the distributions of barriers between protein sub-states involved in the light-induced conformational changes (i.e. - NPHB) are close to glass-like ~1/√V (V is the barrier height), and not to Gaussian. There is a high degree of correlation between the heights of the barriers in the ground and excited states in individual pigment-protein systems, as well as nearly perfect spectral memory. Both NPHB and hole recovery are due to phonon-assisted tunneling associated with the increase of the energy of a scattered phonon. As the latter is unlikely for simultaneously both the hole burning and hole recovery, proteins must exhibit a NPHB mechanism involving diffusion of the free volume towards the pigment. Entities involved in the light-induced conformational changes are characterized by md2 value of about 1.0.10-46 kg.m2. Thus, these entities are protons or, alternatively, small groups of atoms experiencing sub-Å shifts. However, explaining all spectral hole burning and recovery data simultaneously, employing just one barrier distribution, requires a drastic decrease in the attempt frequency to about 100 MHz. This decrease may occur due to cooperative effects. Evidence is presented for excitation energy transfer between the chlorophyll molecules of the adjacent monomers. The magnitude of the dipole-dipole coupling deduced from the delta-FLN spectra is in good agreement with the structural data, indicating that explored protein was intact.Concordia researchers express gratitude to NSERC, CFI and Concordia University. We would also like to acknowledge the financial support by the MINECO (Grant AGL2011-23574) to R. P.Peer reviewe

Parameters of the Protein Energy Landscapes of Several Light-Harvesting Complexes Probed via Spectral Hole Growth Kinetics Measurements

44 Pag., 2 Tabl. The definitive version is available at: http://pubs.acs.org/journal/jpcbfkThe parameters of barrier distributions on the protein energy landscape in the excited electronic state of the pigment/protein system have been determined by means of spectral hole burning for the lowest-energy pigments of CP43 core antenna complex and CP29 minor antenna complex of spinach Photosystem II (PS II) as well as of trimeric and monomeric LHCII complexes transiently associated with the pea Photosystem I (PS I) pool. All of these complexes exhibit sixty to several hundred times lower spectral hole burning yields as compared with molecular glassy solids previously probed by means of the hole growth kinetics measurements. Therefore, the entities (groups of atoms), which participate in conformational changes in protein, appear to be significantly larger and heavier than those in molecular glasses. No evidence of a small (1 cm−1) spectral shift tier of the spectral diffusion dynamics has been observed. Therefore, our data most likely reflect the true barrier distributions of the intact protein and not those related to the interface or surrounding host. Possible applications of the barrier distributions as well as the assignments of low-energy states of CP29 and LHCII are discussed in light of the above results.Research at Concordia University is supported by NSERC and CFI. R.P. would like to thank Spanish MICINN (grant AGL2008-00377). M.S. acknowledges the contribution of the Photosynthetic Systems Program, Chemical Sciences, Geosciences, and Biosciences Division, Basic Energy Sciences, USDOE. J.P. and K.-D.I. gratefully acknowledge support from Deutsche Forschungsgemeinschaft (SFB 429, TP A1, and TP A3, respectively).Peer reviewe

Model of Analysis of Advertising Concerning its Social or Commercial Responsibility

Advertising serves as a mod that shapes social and moral values of the viewer and therefore, due attention should be paid to ensure that the content is healthy, that it positively affects the viewer and the values that inspires represent an ethical improvement of society health. This paper presents a research based on a semi-structured interview and the applying of a questionnaire. The purpose of this research is to reveal the extent to which respondents acknowledge the influence of advertising in decision-making. It can be said that in order to protect society from the harmful effects of advertising, we can create a model with a series of measures that advertising is socially responsible and even beneficial for the society