The synthesis and application of a diazirine-modified uridine analogue for investigating RNA-protein interactions

The roles played by many ncRNAs remain largely unknown. Similarly, relatively little is known about the RNA binding proteins involved in processing ncRNA. Identification of new RNA/RNA binding protein (RBP) interactions may pave the way to gain a better understanding of the complex events occurring within cells during gene expression and ncRNA biogenesis. The development of chemical tools for the isolation of RBPs is of paramount importance. In this context, we report on the synthesis of the uridine phosphoramidite U Dz that bears a diazirine moiety on the nucleobase. RNA probes containing U Dz units were irradiated in the presence of single-stranded DNA binding protein (SSB), which is also known to bind ssRNAs, and shown to efficiently (15% yield) and selectively cross-link to the protein. The corresponding diazirine-modified uridine triphosphate U DzTP was synthesized and its capacity to act as a substrate for the T7 RNA polymerase was tested in transcription assays. U DzTP was accepted with a maximum yield of 38% for a 26mer RNA containing a single incorporation and 28% yield for triple consecutive incorporations. Thus, this uridine analogue represents a convenient biochemical tool for the identification of RNA binding proteins and unraveling the role and function played by ncRNAs.

Combined effect of soil bund with biological soil and water conservation measures in the northwestern Ethiopian highlands

Excessive runoff and soil erosion in the upper Blue Nile Basin poses a threat that has attracted the attention of the Ethiopian government because of the serious on-site effects in addition to downstream effects, such as the siltation of water harvesting structures and reservoirs. The objective of the study was to evaluate and recommend effective biophysical soil and water conservation measure(s) in the Debre Mewi watershed, about 30 km south of the Lake Tana. Six conservation measures were evaluated for their effects on runoff, soil loss, and forage yield using runoff plots. There was a significant difference between treatments for both runoff and soil loss. The four-year average annual soil loss in the different plots ranged from 26 to 71 t ha−1, and total runoff ranged from 180 to 302 mm, while annual rainfall varied between 854 mm in 2008 and 1247 mm in 2011. Soil bund combined with elephant grass had the lowest runoff and soil loss as compared to the other treatments, whereas the untreated control plot had the highest for both parameters. As an additional benefit, 2.8 and 0.7 t ha−1 year−1 of dried forage was obtained from elephant and local grasses, respectively. Furthermore, it was found that soil bund combined with Tephrosia increased soil organic matter by 13% compared to the control plot. Soil bund efficiency was significantly enhanced by combining them with biological measures and improved farmers’ perception of soil and water conservation measures.

Experimental, theoretical and numerical investigation of the nonlinear micromechanical properties of bone

Aging societies suffer from an increasing incidence of bone fractures. Bone strength depends on the amount of mineral measured by clinical densitometry, but also on the micromechanical properties of the bone hierarchical organization. A good understanding has been reached for elastic properties on several length scales, but up to now there is a lack of reliable postyield data on the lower length scales. In order to be able to describe the behavior of bone at the microscale, an anisotropic elastic-viscoplastic damage model was developed using an eccentric generalized Hill criterion and nonlinear isotropic hardening. The model was implemented as a user subroutine in Abaqus and verified using single element tests. A FE simulation of microindentation in lamellar bone was finally performed show-ing that the new constitutive model can capture the main characteristics of the indentation response of bone. As the generalized Hill criterion is limited to elliptical and cylindrical yield surfaces and the correct shape for bone is not known, a new yield surface was developed that takes any convex quadratic shape. The main advantage is that in the case of material identification the shape of the yield surface does not have to be anticipated but a minimization results in the optimal shape among all convex quadrics. The generality of the formulation was demonstrated by showing its degeneration to classical yield surfaces. Also, existing yield criteria for bone at multiple length scales were converted to the quadric formulation. Then, a computational study to determine the influence of yield surface shape and damage on the in-dentation response of bone using spherical and conical tips was performed. The constitutive model was adapted to the quadric criterion and yield surface shape and critical damage were varied. They were shown to have a major impact on the indentation curves. Their influence on indentation modulus, hardness, their ratio as well as the elastic to total work ratio were found to be very well described by multilinear regressions for both tip shapes. For conical tips, indentation depth was not a significant fac-tor, while for spherical tips damage was insignificant. All inverse methods based on microindentation suffer from a lack of uniqueness of the found material properties in the case of nonlinear material behavior. Therefore, monotonic and cyclic micropillar com-pression tests in a scanning electron microscope allowing a straightforward interpretation comple-mented by microindentation and macroscopic uniaxial compression tests were performed on dry ovine bone to identify modulus, yield stress, plastic deformation, damage accumulation and failure mecha-nisms. While the elastic properties were highly consistent, the postyield deformation and failure mech-anisms differed between the two length scales. A majority of the micropillars showed a ductile behavior with strain hardening until failure by localization in a slip plane, while the macroscopic samples failed in a quasi-brittle fashion with microcracks coalescing into macroscopic failure surfaces. In agreement with a proposed rheological model, these experiments illustrate a transition from a ductile mechanical behavior of bone at the microscale to a quasi-brittle response driven by the growth of preexisting cracks along interfaces or in the vicinity of pores at the macroscale. Subsequently, a study was undertaken to quantify the topological variability of indentations in bone and examine its relationship with mechanical properties. Indentations were performed in dry human and ovine bone in axial and transverse directions and their topography measured by AFM. Statistical shape modeling of the residual imprint allowed to define a mean shape and describe the variability with 21 principal components related to imprint depth, surface curvature and roughness. The indentation profile of bone was highly consistent and free of any pile up. A few of the topological parameters, in particular depth, showed significant correlations to variations in mechanical properties, but the cor-relations were not very strong or consistent. We could thus verify that bone is rather homogeneous in its micromechanical properties and that indentation results are not strongly influenced by small de-viations from the ideal case. As the uniaxial properties measured by micropillar compression are in conflict with the current literature on bone indentation, another dissipative mechanism has to be present. The elastic-viscoplastic damage model was therefore extended to viscoelasticity. The viscoelastic properties were identified from macroscopic experiments, while the quasistatic postelastic properties were extracted from micropillar data. It was found that viscoelasticity governed by macroscale properties has very little influence on the indentation curve and results in a clear underestimation of the creep deformation. Adding viscoplasticity leads to increased creep, but hardness is still highly overestimated. It was possible to obtain a reasonable fit with experimental indentation curves for both Berkovich and spherical indenta-tion when abandoning the assumption of shear strength being governed by an isotropy condition. These results remain to be verified by independent tests probing the micromechanical strength prop-erties in tension and shear. In conclusion, in this thesis several tools were developed to describe the complex behavior of bone on the microscale and experiments were performed to identify its material properties. Micropillar com-pression highlighted a size effect in bone due to the presence of preexisting cracks and pores or inter-faces like cement lines. It was possible to get a reasonable fit between experimental indentation curves using different tips and simulations using the constitutive model and uniaxial properties measured by micropillar compression. Additional experimental work is necessary to identify the exact nature of the size effect and the mechanical role of interfaces in bone. Deciphering the micromechanical behavior of lamellar bone and its evolution with age, disease and treatment and its failure mechanisms on several length scales will help preventing fractures in the elderly in the future.

Rapid method to express and purify human membrane protein using the Xenopus oocyte system for functional and low-resolution structural analysis.

Progress toward elucidating the 3D structures of eukaryotic membrane proteins has been hampered by the lack of appropriate expression systems. Recent work using the Xenopus oocyte as a novel expression system for structural analysis demonstrates the capability of providing not only the significant amount of protein yields required for structural work but also the expression of eukaryotic membrane proteins in a more native and functional conformation. There is a long history using the oocyte expression system as an efficient tool for membrane transporter and channel expression in direct functional analysis, but improvements in robotic injection systems and protein yield optimization allow the rapid scalability of expressed proteins to be purified and characterized in physiologically relevant structural states. Traditional overexpression systems (yeast, bacteria, and insect cells) by comparison require chaotropic conditions over several steps for extraction, solubilization, and purification. By contrast, overexpressing within the oocyte system for subsequent negative-staining transmission electron microscopy studies provides a single system that can functionally assess and purify eukaryotic membrane proteins in fewer steps maintaining the physiological properties of the membrane protein.

Migration and population expansion of Abies, Fagus, Picea, and Quercus since 15000 years in and across the Alps, based on pollen-percentage threshold values

Aims: The aim of this study is to explore the migration (colonization of new areas) and subsequent population expansion (within an area) since 15 ka cal BP of Abies, Fagus, Picea, and Quercus into and through the Alps solely on the basis of high-quality pollen data. Methods: Chronologies of 101 pollen sequences are improved or created. Data from the area delimited by 45.5–48.1°N and 6–14°E are summarized in three ways: (1) in a selection of pollen-percentage threshold maps (thresholds 0.5%, 1%, 2%, 4%, 8%, 16%, and 32% of land pollen); (2) in graphic summaries of 250-year time slices and geographic segments (lengthwise and transverse in relation to the main axis of the Alps) as pollen-percentage curves, pollen-percentage difference curves, and pollen-percentage threshold ages cal BP graphed against both the length and the transverse Alpine axes; and (3) in tables showing statistical relationships of either pollen-percentage threshold ages cal BP or pollen expansion durations (=time lapse between different pollen-percentage threshold ages cal BP) with latitude, longitude, and elevation; to establish these relationships we used both simple linear regression and multiple linear regression after stepwise-forward selection. Results: The statistical results indicate that (a) the use of pollen-percentage thresholds between 0.5% and 8% yield mostly similar directions of tree migration, so the method is fairly robust, (b) Abies migrated northward, Fagus southward, Picea westward, and Quercus northward; more detail does not emerge due to an extreme scarcity of high-quality data especially along the southern foothills of the Alps and in the eastern Alps. This scarcity allows the reconstruction of one immigration route only of Abies into the southern Alps. The speed of population expansion (following arrival) of Abies increased and of Picea decreased during the Holocene, of Fagus it decreased especially during the later Holocene, and of Quercus it increased especially at the start of the Holocene.

Search for Low-Molecular-Weight Biomarkers in Plant Tissues and Seeds Using Metabolomics: Tools, Strategies, and Applications

This chapter summarises the metabolomic strategies currently in force used in plant science and describes the methods used. The metabolite profiling and fingerprinting of plant tissues through MS- and/or NMR-based approaches and the subsequent identification of biomarkers is detailed. Strategies for the microisolation and de novo identification of unknown biomarkers are also discussed. The various approaches are illustrated by a metabolomic study of the maize response to herbivory. A review of recent metabolomic studies performed on seed and crop plant tissues involving various analytical strategies is provided.

Hydrolytic behaviour of mono-and dithiolato-bridged dinuclear arene ruthenium complexes and their interactions with biological ligands

The hydrolysis and the reactivity of two dinuclear p-cymene ruthenium monothiolato complexes, [(η6-p-MeC6H4Pri)2Ru2Cl2(µ-Cl)(µ-S-m-9-B10C2H11)] (1) and [(η6-p-MeC6H4Pri)2¬Ru2Cl2(µ-Cl)¬(µ-S¬CH2-p-C6H4-NO2)] (2), and of two dinuclear p-cymene ruthenium dithiolato complexes, [(η6-p-MeC6H4Pri)2Ru2(µ-SCH2CH2Ph)2Cl2] (3) and [(η6-p-Me¬C6H4¬Pri)2¬Ru2(S¬CH2¬C6H4-p-O¬Me)2¬Cl2] (4) towards amino acids, nucleotides, and a single-stranded DNA dodecamer were studied using NMR and mass spectrometry. In aqueous solutions at 37 °C, the monothiolato com¬plexes 1 and 2 undergo rapid hydrolysis, irrespective of the pH value, the predominant species in D2O/acetone-d6 solution at equilibrium being the neutral hydroxo complexes [(η6-p-Me¬C6H4¬Pri)2Ru2(OD)2(µ-OD)(µ-SR)]. The dithiolato complexes 3 and 4 are stable in water under acidic conditions, but undergo slow hydrolysis under neutral and basic conditions. In both cases, the cationic hydroxo complexes [(η6-p-MeC6H4Pri)2Ru2(µ-SR)2¬(OD)¬(CD3CN)]+ are the only spe¬cies observed in D2O/CD3CN at equilibrium. Surprisingly, no adducts are observed upon addition of an excess of L-methionine or L-histidine to the aqueous solutions of the complexes. Upon addition of an excess of L-cysteine, on the other hand, 1 and 2 form the unusual cationic trithiolato complexes [(η6-p-MeC6H4Pri)2¬Ru2{µ-SCH2CH(NH2)COOH}2(µ-SR)]+ containing two bridging cysteinato li¬gands, while 3 and 4 yield cationic trithiolato complexes [(η6-p-MeC6H4Pri)2Ru2[µ-SCH2CH¬(NH2)COOH](µ-SR)2]+ containing one bridging cysteinato ligand. A representative of catio¬nic trithiolato complexes containing a cysteinato bridge of this type, [(η6-p-MeC6H4Pri)2¬Ru2[µ-S¬CH2CH(NH2)COOH](µ-SCH2-p-C6H4-But)2]+ (6) could be synthesised from the di¬thiolato complex [(η6-p-Me¬C6H4¬Pri)2-Ru2(S¬CH2¬C6H4-p-But)2Cl2] (5), isolated as the tetra¬fluo¬ro¬borate salt and fully characterised. Moreover, the mono- and dithiolato complexes 1 - 4 are inert toward nucleotides and DNA, suggesting that DNA is not a target of cytotoxic thiolato-bridged arene ruthenium complexes. In contrast to the trithiolato complexes, monothiolato and dithio¬lato complexes hydrolyse and react with L-cysteine. These results may have im¬portant implications for the mode of action of thiolato-bridged dinuclear arene ruthenium drug candidates, and suggest that their modes of action are different to those of other arene ruthenium complexes.

Gibberellin Deficiency Confers Both Lodging and Drought Tolerance in Small Cereals

Tef [Eragrostis tef (Zucc.) Trotter] and finger millet [Eleusine coracana Gaertn] are staple cereal crops in Africa and Asia with several desirable agronomic and nutritional properties. Tef is becoming a life-style crop as it is gluten-free while finger millet has a low glycemic index which makes it an ideal food for diabetic patients. However, both tef and finger millet have extremely low grain yields mainly due to moisture scarcity and susceptibility of the plants to lodging. In this study, the effects of gibberellic acid (GA) inhibitors particularly paclobutrazol (PBZ) on diverse physiological and yield-related parameters were investigated and compared to GA mutants in rice (Oryza sativa L.). The application of PBZ to tef and finger millet significantly reduced the plant height and increased lodging tolerance. Remarkably, PBZ also enhanced the tolerance of both tef and finger millet to moisture deficit. Under moisture scarcity, tef plants treated with PBZ did not exhibit drought-related symptoms and their stomatal conductance was unaltered, leading to higher shoot biomass and grain yield. Semi-dwarf rice mutants altered in GA biosynthesis, were also shown to have improved tolerance to dehydration. The combination of traits (drought tolerance, lodging tolerance and increased yield) that we found in plants with altered GA pathway is of importance to breeders who would otherwise rely on extensive crossing to introgress each trait individually. The key role played by PBZ in the tolerance to both lodging and drought calls for further studies using mutants in the GA biosynthesis pathway in order to obtain candidate lines which can be incorporated into crop-breeding programs to create lodging tolerant and climate-smart crops.

The Skip To Breakfast project: Development, implementation, and feasibility evaluation of an intervention to increase healthful breakfast consumption among fifth grade students and their families

Children and adults frequently skip breakfast and rates are currently increasing. In addition, the food choices made for breakfast are not always healthy ones. Breakfast skipping, in conjunction with unhealthy breakfast choices, leads to impaired cognitive functioning, poor nutrient intake, and overweight. In response to these public health issues, Skip To Breakfast, a behaviorally based school and family program, was created to increase consistent and healthful breakfast consumption among ethnically diverse fifth grade students and their families, using Intervention Mapping™. Four classroom lessons and four parent newsletters were used to deliver the intervention. For this project, a healthy, "3 Star Breakfast" was promoted, and included a serving each of dairy product, whole grain, and fruit, each with an emphasis on being low in fat and sugar. The goal of this project was to evaluate the feasibility and acceptability of the intervention. A pilot-test of the intervention was conducted in one classroom, in a school in Houston, during the Fall 2007 semester. A qualitative evaluation of the intervention was conducted, which included focus groups with students, phone interviews of parents, process evaluation data from the classroom teacher, and direct observation. Sixteen students and six parents participated in the study. Data were recorded and themes were identified. Initial results showed there is a need for such programs. Based on the initial feedback, edits were made to the intervention and program. Results showed high acceptability among the teacher, students, and parents. It became apparent that students were not reliably getting the parent newsletters to their parents to read, so a change to the protocol was made, in which students will receive incentives for having parents read newsletters and return signed forms, to increase parent participation. Other changes included small modifications to the curriculum, such as, clarifying instructions, changing in-class assignments to homework assignments, and including background reading materials for the teacher. The main trial is planned to be carried out in Spring 2008, in two elementary schools, utilizing four, fifth grade classes from each, with one school acting as the control and one as the intervention school. Results from this study can be used as an adjunct to the Coordinated Approach To Child Health (CATCH) program. ^

Food advertisements during children's television programming in 2007: Comparison with ads in 1994 and the 2005 dietary recommendations

Childhood overweight and obesity are two major public health problems that are of economic and medical concern in the world today (Lobstein, Baur, & Uauy, 2004). Overweight conditions in childhood are important because they are widely prevalent, serious, and carry lifetime consequences for health and well being (Lobstein et al., 2004). Several studies have shown an association between television viewing and obesity in all age groups (Caroli, Argentieri, Cardone, & Masi, 2004; Harper, 2006; Vandewater & Huang, 2006; Wiecha et al., 2006). One mechanism that potentially links television viewing to childhood obesity is food advertising (Story, 2003). ^ The purpose of this study was to examine the types of foods advertised on children's television programming and to determine if there have been any changes in the number and types of commercials over the last 13 years. In addition, the food content of the advertisements was compared to the 2005 Dietary Guidelines to determine if the foods targeted were consistent with the current recommendations. Finally, each television network was analyzed individually to determine any differences between advertising on cable and regular programming. ^ A descriptive analysis was conducted on the most commonly advertised commercials during children's television programming on Saturday morning from 7 a.m. to 10:30 a.m. A total of 10 major television networks were viewed on three different Saturday mornings during June and July 2007. Commercial advertising accounted for approximately 19% of children's total viewing time. Of the 3,185 commercials, 28.5% were for foods, 67.7% were for non-food items, and 3.8% were PSAs. On average, there were 30 commercial advertisements and PSAs per hour, of which approximately nine were for food. ^ Of the 907 food advertisements, 72.0% were for foods classified in the fats, oils, and sugar group. The next largest group (17.3%) was for restaurant food of which 15.3% were for unhealthy/fast food restaurant fare. The most frequently advertised food product on Saturday morning television was regular cereal, accounting for 43.9% of all food advertisements. ^ Cable and regular programming stations varied slightly in the amount, length, and category of commercials. Cable television had about 50% less commercials and PSAs (1098) than regular programming (2087), but only had approximately 150 minutes less total commercial and PSA time; therefore, cable, in general, had longer commercials than regular programming. Overall, cable programming had more advertisements encouraging increased physical activity and positive nutrition behavior with less commercials focusing on the fats, oils, and sugar groups, compared to regular programming. ^ During the last 13 years, food advertisements have not improved, despite the recent IOM report on marketing foods to children (Institute of Medicine-Committee on Food Marketing and the Diets of Children and Youth, 2005), although the frequency of food advertisements has improved slightly. Children are now viewing an average of one food advertisement every 7 minutes, compared to one food advertisement every 5 minutes in 1994 (Kotz & Story, 1994). Therefore, manufacturers are putting a greater emphasis on advertising other products to children. Despite the recent attention to the issue of marketing unhealthy foods to children through television advertisements, not much progress has been noted since 1994. Further advocacy and regulatory issues concerning the content of advertisements during Saturday morning TV need to be explored. ^

The impact of a cooking and gardening summer camp experience on the fruit and vegetable consumption of elementary school-aged children

Childhood obesity is a significant public health problem. Over 15 percent of children in the United States are obese, and about 25 percent of children in Texas are overweight (CDC NHANES). Furthermore, about 30 percent of elementary school aged children in Harris County, Texas are overweight or obese (Children at Risk Institute 2010). In addition to actions such as increasing physical activity, decreasing television watching and video game time, decreasing snacking on low nutrient calorie dense foods and sugar sweetened beverages, children need to consume more fruits and vegetables. According to the National Health and Nutrition Examination Survey (NHANES) from 2002, about 26 percent of U.S. children are meeting the recommendations for daily fruit intake and about 16 percent are meeting the recommendations for daily vegetable intake (CDC NHANES). In 2004, the average total intake of vegetables was 0.9 cups per day and 1.1 cups of fruit per day by children ages four to nine years old in the U.S. (CDC NHANES). Not only do children need effective nutrition education to learn about fruits and vegetables, they also need access and repeated exposure to fruits and vegetables (Anderson 2009, Briefel 2009). Nutrition education interventions that provide a structured, hands-on curriculum such as school gardens have produced significant changes in child fruit and vegetable intake (Blair 2009, McAleese 2007). To prevent childhood obesity from continuing into adolescence and adulthood, effective nutrition education interventions need to be implemented immediately and for the long-term. However, research has shown short-term nutrition education interventions such as summer camps to be effective for significant changes in child fruit and vegetable intake, preferences, and knowledge (Heim 2009). ^ A four week summer camp based on cooking and gardening was implemented at 6 Multi-Service centers in a large, urban city. The participants included children ranging in age from 7 to 14 years old (n=64). The purpose of the camp was to introduce children to their food from the seed to the plate through the utilization of gardening and culinary exercises. The summer camp activities were aimed at increasing the children's exposure, willingness to try, preferences, knowledge, and intake of fruits and vegetables. A survey was given on the first day of camp and again on the last day of camp that measured the pre- and post differences in knowledge, intake, willingness to try, and preferences of fruits and vegetables. The present study examined the short-term effectiveness of a cooking and garden-based nutrition education program on the knowledge, willingness, preferences, and intake among children aged 8 to 13 years old (n=40). The final sample of participants (n=40) was controlled for those who completed pre- and post-test surveys and who were in or above the third grade level. Results showed a statistically significant increase in the reported intake of vegetables and preferences for vegetables, specifically green beans, and fruits. There was also a significant increase in preferences for fruits among boys and participants ages 11 to 13 years. The results showed a change in the expected direction of willingness to try, preferences for vegetables, and intake of fruit, however these were not statistically significant. Interestingly, the results also showed a decrease in the intake of low nutrient calorie dense foods such as sweets and candy.^

Homology Cloning, Heterologous Expression and Characterization of a New Channelrhodopsin

Channelrhodopsins are phototaxis receptors in the plasma membranes of motile unicellular algae. They function as light-gated cation channels and this channel activity has been exploited to trigger action potentials in neurons with light to control neural circuits (“optogenetics"). Four channelrhodopsins were identified in two algal species, Chlamydomonas reinhardtii and Volvox carteri, with known genome sequences; each species contains 2 channelrhodopsins, one absorbing at longer wavelengths and one at shorter wavelengths, named CrChR1 and CrChR2, respectively. Our goals are to expand knowledge of channelrhodopsin mechanisms and also to identify new channelrhodopsins from various algal species with improved properties for optogenetic use. For these aims we are targeting algae from extreme environments to establish the natural diversity of their properties. We cloned a new channelrhodopsin from the psychrophilic (cold-loving) alga, Chlamydomonas augustae, with degenerate primers based on the 4 known homologs. The new protein is 48% and 52% identical to CrChR1 and CrChR2, respectively. We expressed the channelrhodopsin in HEK293 cells and measured light-induced currents to assess their kinetics and action spectrum. Based on the primary structure, kinetics of light-induced photocurrents in HEK293 cells, and action spectrum maximum of 520 nm near that of the two previously found CrChR1, we named the new channelrhodopsin CaChR1. The properties of robust channel activity at physiological pH, fast on-and-off kinetics, and greatly red-shifted action spectrum maximum from that of CrChR2, make CaChR1 advantageous as an optogenetic tool. To know this new channelrhodopsin better, we expressed His-tagged CaChR1 in Pichia pastoris and the yield is about 6 mg/L. The purified His-tagged CaChR1 exhibited an absorption spectrum identical to the action spectrum of CaChR1-generated photocurrents. The future work will be measurement of the photocycles of CaChR1 by flash photolysis, crystallization of CaChR1 for the structure and mutagenesis of CaChR1 to find the critical amino acids accounting for red-shifted spectra, slow inactivation and rapid on-and-off kinetics. Seven new channelrhodopsins including CaChR1 from different algal species have been cloned in our lab at this time, bringing the total known to 13. The work of cloning of these new channelrhodopsins along with the expression of CaChR1 was published in Photochemistry and Photobiology in January 2012

Soil and Plant Fertility Management for Soybeans

Producers utilizing a two year rotation of corn and soybean often apply fertilizer on a biannual basis, spreading recommended amounts of phosphorus and potassium for both crops prior to corn establishment. This approach minimizes application costs and is in accordance with university fertility recommendations that have found a low probability of fertilizer yield response when soils tested at the medium/optimum level or above. However, the field trials on which these state recommendations were developed are often several decades old. Increases in average corn and soybean yields and associated increases in crop nutrient removal rates have called into question the validity of these recommendations for current production environments. This study investigated the response of soil test levels and grain yield to annual and biannual fertilizer applications made at 1x and 2x rates of current university fertilizer recommendations.

Placement Methods of Phosphorus and Potassium for Corn and Soybean Managed with No-till and Chisel-plow/Disk Tillage

No-till management limits the incorporation of crop residue and fertilizer with soil resulting in wetter, colder soils and the accumulation of organic matter, phosphorus (P), and potassium (K) near the soil surface. Banding of P and K could be more effective than broadcast fertilization by counteracting stratification, applying nutrients in the root zone (starter effect), and minimizing reactions with the soil that may reduce their availability to plants. Therefore, this long-term study was established in 1994 to evaluate P and K fertilizer placement methods and grain yield of corn-soybean rotations managed with notill and chisel-plow/disk tillage.

Avian species identity and predation success in tropical cacao agroforestry of the Napu Valley in Central Sulawesi, Indonesia

Avian ecosystem services such as the suppression of pests are considered being of high ecological and economic importance in a range of ecosystems, especially in tropical agroforestry. But how bird predation success is related to the diversity and composition of the bird community, as well as local and landscape factors, is poorly understood. The author quantified arthropod predation in relation to the identity and diversity of insectivorous birds, using experimental exposure of artificial, caterpillar-like prey on smallholder cacao agroforestry systems, differing in local shade management and distance to primary forest. The bird community was assessed using both mist netting (targeting on active understory insectivores) and point count (higher completeness of species inventories) sampling. The study was conducted in a land use dominated area in Central Sulawesi, Indonesia, adjacent to the Lore Lindu National Park. We selected 15 smallholder cacao plantations as sites for bird and bat exclosure experiments in March 2010. Until July 2011, we recorded several data in this study area, including the bird community data, cacao tree data and bird predation experiments that are presented here. We found that avian predation success can be driven by single and abundant insectivorous species, rather than by overall bird species richness. Forest proximity was important for enhancing the density of this key species, but did also promote bird species richness. The availability of local shade trees had no effects on the local bird community or avian predation success. Our findings are both of economical as well as ecological interest because the conservation of nearby forest remnants will likely benefit human needs and biodiversity conservation alike.