Seasonal patterns of forest canopy and their relevance for the global carbon cycle

In the terrestrial biosphere forests have a significant role as a carbon sink. Under recent climate change, it is increasingly important to detect seasonal change or ‘phenology’ that can influence the global carbon cycle. Monitoring canopies using camera systems has offered an inexpensive means to quantify the phenological changes. However, the reliability is not well known. In order to examine the usefulness of cameras to observe forest phenology, we analysed canopy images taken in two deciduous forests in Japan and England and investigate which colour index is best for tracking forest phenology and predict carbon uptake by trees. A camera test using model leaves under controlled conditions has also carried out to examine sensitivity of colour indices for discriminating leaf colours. The main findings of the present study are: 1) Time courses of colour indices derived from images taken in deciduous forests showed typical patterns throughout the growing season. Although cameras are not calibrated instrument, analysis of images allowed detecting the timings of phenological events such as leaf onset and leaf fall; 2) The strength of the green channel (or chromatic coordinate of green) was useful to observe leaf expansion as well as damage by spring late frost. However, the results of the camera test using model leaves suggested that this index was not sufficiently sensitive to detect leaf senescence. Amongst colour indices, Hue was the most robust metric for different cameras, different atmospheric conditions and different distances. The test also revealed Hue was useful to track nitrogen status of leaves; 3) Modelling results using a light use efficiency model for GPP showed a strong relationship between GPP and Hue, which was stronger than the relationships using alternative traditional indices

Significado ecológico de la acumulación de flavonoides en tejidos reproductivos y vegetativos en Silene littorea (Caryophyllaceae)

Programa de Doctorado en Medio Ambiente y SociedadLínea de Investigación: Biodiversidad y Biología de la ConservaciónClave Programa: DAMCódigo Línea: 83Anthocyanins are one of the main pigments conferring color to flowers. These compounds may be also accumulated in vegetative tissues, where perform multiple protective roles against different biotic and abiotic stressors. In the same metabolic route of anthocyanins, other non-anthocyanin flavonoids that confer protection against a wide diversity of environmental stresses are also synthesized. Thus, the study of anthocyanins and other flavonoids is key to understand the importance of these metabolites in the adaptation process of plants to their environments. In this thesis, we investigate the adaptive role of flavonoids analyzing the ecological and evolutionary significance of flavonoid accumulation in reproductive and vegetative tissues of plants, using Silene littorea (Caryophyllaceae) as a model organism. This species is endemic of the Iberian Peninsula, growing at the sea level on coastal ecosystems. The flowers of S. littorea are pink due to the accumulation of anthocyanins. The presence of anthocyanins in calyces, leaves and stems confers a coloration that vary from green to red depending on the concentration of pigments accumulated. In addition, non-anthocyanin flavonoids are also produced in all plant organs. The ability of S. littorea to synthesize anthocyanins and non-anthocyanin flavonoids in the whole plant allow us to study how these compounds are accumulated in different plant tissues, the possible relationships among tissues in flavonoid production and the degree of phenotypic plasticity of this response. We also studied the physiological, biochemical and genetic changes that UV light exposure induces in this species. In addition, S. littorea also displays white plants with localized absence of anthocyanins in petals or a complete absence of these pigments in the whole plant. This feature of the species offers an excellent opportunity to investigate the relevance of these secondary metabolites in plant development and survival. Finally, we develop a fast, efficient and non-invasive method for estimating anthocyanin concentrations in plants by using digital images. In S. littorea, each plant organ exhibited considerable variability in the content of anthocyanins and other flavonoids both within and among populations. At the plant level, the flavonoid content in petals, calyxes, and leaves was not correlated in most of the populations. However, at the population level, the mean amount of anthocyanins in all organs was positively correlated, which suggests that the variable environmental conditions of populations may play a role in anthocyanin accumulation. In populations on the west coast of the Iberian Peninsula, a general pattern of increasing accumulation of flavonoids toward southern latitudes was observed in photosynthetic tissues. This pattern corresponds to a gradual increase of UV-B radiation and temperature, and a decrease of rainfall toward the south. The study of plasticity in flavonoid production revealed that the synthesis of both anthocyanins and flavones is mostly plastic in photosynthetic tissues, being mainly influenced by environmental effects. In addition, flavones exhibited approximately half the degree of phenotypic plasticity compared to anthocyanins. On the other hand, petals showed limited plasticity in flavonoid production. These results suggest that anthocyanins are usually constitutive in petals, yet susceptible to environmental conditions in photosynthetic tissues. We found that UV light stimulated the production of both anthocyanins and flavones, especially these latter in photosynthetic tissues. The synthesis of effective antioxidant flavones in photosynthetic tissues suggest that these compounds may have a key role as antioxidants and a minor role as light filters. In addition, UV light also induced a modest activation of specific transcription factors, decreased the photochemical efficiency of photosystem II and had a negative influence on plant fitness. The study of polymorphism in the flavonoid production showed that loss of anthocyanins, either in petals or in the whole plant, does not influence the ability of this species to synthesize flavones. Flavones have important protective functions for plants, similar to those of anthocyanins. We suggested that lack of anthocyanins may involve deleterious pleiotropic effects for plant survival not associated to their protective functions, which would explain the scarcity of non-pigmented plants in natural populations. Finally, we showed that our method based on digital images can be applied for accurately estimate anthocyanin concentration in photosynthetic and non-photosynthetic tissues. The most accurate estimations were obtained from color indices that stated the ratio of the G channel over the R and/or B channels or that reflect variations in the G channel.Universidad Pablo de Olavide de Sevilla. Departamento de Biología Molecular e Ingeniería BioquímicaPostprin

Light-sheet fluorescent microscopy in tardigrade anoxybiosis

Tardigrades are invertebrates that are known for their tolerance to extreme conditions. This research focuses on anoxia, the total lack of oxygen, and the adaptation and survival of anoxiainduced experiments. Cryptobiosis is a form of dormancy that enables the survival of the animals, however, many forms of cryptobiosis are still poorly understood and the mechanisms and physiological responses are not entirely explained. This study aimed to create a protocol that utilizes fluorescent dyes to visualize the transition into anoxybiosis and morphometric changes at the cellular level involved in the phenomenon. Lightsheet fluorescent microscopy enabled fast 3D volumetric scanning of the transition and revealed what happened to the animal when anoxia was chemically applied. Results were aligned with the expectations: during anoxybiosis, tardigrades became immobilized and swollen leading to the relocation and reorganization of cells. Importantly it was observed that variation throughout the experiments was quite significant and in further studies, this should be outlined. In this research, two specimens of M. ripperi were used and obtained data were compared including cell number, volume, and displacement over time. The most fundamental issue is how to gain stable and reproducible results. Tardigrade cuticle and overall variation of body state of the animals create sources of error, particularly dyeing by soaking. By soaking, there are very few possibilities to control, how the dye is distributed and attached to the cellular compartments, therefore in this study we did not pay so close attention to the statistical significance of the results. Animals chosen for the experiments were random and therefore variables such as sex, age, and fasting were not included. Fluorescent microscopy is a widely used method in biological studies and this study showed that it can be used in live imaging of tardigrades. However, as a pilot experiment, this led to many open questions and features to improve, especially in the image analysis part. Large datasets need a lighter pipeline to gain a higher throughput method. In the future, the (light sheet) fluorescent imaging can be a beneficial tool for similar cellular studies; however, the individual sources of variation need to be minimized. Tardigrades can be a promising model organism for studies including cell survival, cancer research, and storage and storing solutions for various drug components when understanding the mechanisms that enable the animal stress tolerance and survival

Anthocyanins

This book contains 20 articles published in Molecules that concern the color quality of food and wine, anthocyanin biosynthesis and regulation, anthocyanin composition and the biological properties of anthocyanin pigments

Interpreting canopy development and physiology using the EUROPhen camera network at flux sites

Peer reviewe

Conjugated polymers based on polyfluorene derivatives and polypyrrole

Ankara : The Department of Chemistry and the Institute of Engineering and Sciences of Bilkent University, 2007.Thesis (Master's) -- Bilkent University, 2007.Includes bibliographical references leaves 90-94.In this thesis, a series of polyfluorene based copolymers have been prepared via Suzuki Coupling for use in light emitting diodes (LEDs). Polyfluorene based polymers are synthesized from different monomers. These polymers are characterized with spectroscopic techniques including FT-IR, UV-VIS, Fluorescence and 1H, 13C NMR. Conjugated polymers are attractive chemical structures inherently allowing charge transport. However, in the solid state, conjugated polymers lack stability and form aggregates. To overcome this problem, conjugated polymers can be converted to insulated molecular wires. This can be achieved by separation of the conjugated polymer chains by a macrocycle. In this study, encapsulation of conjugated polymers is tried with two methods. First method is to encapsulate the polymer main chain by macrocycles. Polypyrrole based polypseudorotaxane is prepared in this way. Pyrrole is complexed with the cucurbit[6]uril (CB(6)) and following chemical oxidation by FeCl3 in acidic medium yields the desired polypseudorotaxane. Spectroscopic investigations such as FT-IR, UV-VIS, Fluorescence and 1H-NMR confirm the formation of polypyrrole based polypseudorotaxane. The second method involves the rotaxanation of the polymer side chains. For this purpose, fluorene based monomers are chosen because the 9th position of fluorene can be easily functionalized. After attaching suitable groups to the 9th position of fluorene, the rotaxane formation was attempted via 1,3 dipolar cycloaddition in the presence of CB(6). A white light emitting diode is prepared using a hybrid inorganic and organic material based system. Prepared conjugated polymers were used in white light generation. Good results are obtained with high CRI indices. Also the thermal stability of the conjugated polymers is studied by FT-IR, UV-VIS and Fluorescence spectroscopic techniques under heat exposure.Koldemir, ÜnsalM.S

PRECISION MEASUREMENT TO STUDY STRONGLY CORRELATED SYSTEMS-FROM A SINGLE ION TO PHONONS IN AN ION CHAIN

Ph.DDOCTOR OF PHILOSOPH