Frugivore behavior and plant spatial genetics

Spatial genetics aims to understand the influence of environmental features and biological interactions on gene flow and genetic structure. In plants, spatial genetics is determined by the rate, pattern and spatial extent of gene dispersal within and between populations. Gene dispersal in plants is composed by seed dispersal and pollination. Seed dispersal increases the probabilities of mating between spatially distant, non-related, individuals, reducing the probability of biparental inbreeding, decreasing the incidence of unfavorable traits and increasing genetic diversity. In animal seed dispersal, foraging behavior and post-feeding movement range affect seed dispersal pattern and distance, with consequences in plant spatial genetics. This thesis aims to understand the relationship between frugivore behavior and spatial genetics while strengthening the current knowledge on seed dispersal by tamarins and using their dispersal of Leonia cymosa as a case study for a finer analysis of the effect of frugivore behavior on spatial genetics. Leonia cymosa Mart. (Violaceae), a small Neotropical understory tree, is exclusively dispersed at our study site by tamarins, Saguinus mystax, and Leontocebus nigrifrons. Leonia cymosa is, therefore, a good model for understanding the effects of frugivore behavior and plants spatial genetics. First, I analyzed the presence and strength of SGS in animal-dispersed plants studied in the last 20 years. I found animal behavior has an effect on spatial genetic structure, but pollination and marker type used could also have an influence on the strength of SGS. Second, I analyze seed dispersal distance of Leonia cymosa by tamarins, using plant genetics and animal behavior data in parallel. Methods for estimating seed dispersal distance did not differ significantly and mean seed dispersal distance for Leonia cymosa was between 218 and 304m. Third, I analyze spatial genetic structure (SGS) in Leonia cymosa through its life stages and put it in the context of tamarin behavior. SGS was present in seedlings, and weaker in juveniles and absent in adults of Leonia cymosa, likely due to tamarin seed dispersal patterns and extent. Clumped seed dispersal patterns might have a strong influence on SGS of seedlings, while the combination of-density-dependent mortality and relatively long seed dispersal distance likely reduces this effect in adulthood. Fourth, I analyzed the genetic composition of Leonia cymosa individuals growing on different tamarin home ranges. Home ranges were expected to create a seed dispersal barrier influencing overall gene flow. However, even though the parentage analysis showed no seed exchange across home ranges, genetic makeup shows no difference between individuals located in different home ranges, at all life stages, giving evidence that pollination or small shifts in time of home ranges, could have a strong effect in maintaining gene flow across home ranges. The results of this thesis give evidence that seed dispersal patterns and distance can strongly and differently affect plant spatial genetic structure, while, pollination might play an important role in maintaining gene flow in case of seed dispersal constraints

MAPK Cascade Possesses Decoupled Controllability of Signal Amplification and Duration

AbstractThe three important characteristics of the output signal of mitogen activated protein kinase (MAPK) cascade are time delay between stimulus and response, amplitude gain, and duration of the output signal. In this study, we performed a sensitivity analysis on the computational model of epidermal growth factor receptor (EGFR) activated MAPK cascade developed by Schoeberl and co-workers (1) to identify the sensitive steps of the pathway affecting these characteristics. We show that the signaling network is sensitive in a decoupled manner, which provides the ability to control its output amplitude and duration one at a time. Signal duration is found sensitive only to the phosphatase reactions at the MEK level. In contrast, signal amplitude is found most sensitive to the phosphatase reactions at the ERK level. Time delay is found to be a robust characteristic of the system

Aerosol Jet Printing of a Benzocyclobutene-Based Ink as Adhesive Material for Wafer Bonding Application

Aerosol jet printing (AJP) is an emerging additive manufacturing technology that is gaining increasing attention in the electronic field. Several studies have been carried out on the AJP of conductive, semiconductive, and dielectric polymers for electronic applications. However, wafer bonding is an application that is still uncovered by literature. Therefore, in this work, the AJP of benzocyclobutene (BCB) as a polymeric adhesive for wafer bonding is presented for the first time. A thorough characterization of the processing parameters is carried out to identify the most ideal conditions for printing at a relatively high speed. Then, square patterns are printed, proving the versatility of the AJP technology in terms of the reachable thickness of the deposited BCB patterns. Complex patterns with a resolution of approximate to 60 mu m are also printed. The bonding properties of the BCB are characterized from a morphological and mechanical point of view. In particular, the shear strength of the BCB coatings deposited with AJP is approximate to 39 MPa and it is comparable with the shear strength of BCB coating deposited by spin-coating. Consequently, AJP represents a valid alternative for the deposition of polymeric adhesive for wafer bonding

Phosphorus recovery from a pilot-scale grate furnace: influencing factors beyond wet chemical leaching conditions

Phosphorus is a non-renewable resource going to exhaustion in the future. Sewage sludge ash is a promising secondary raw material due to its high phosphorus content. In this work, the distribution of 19 elements in bottom and cyclone ashes from pilot-scale grate furnace have been monitored to determine the suitability for the phosphorus acid extraction. Moreover, the influence of some parameters beyond wet chemical leaching conditions were investigated. Experimental results showed that bottom ash presented lower contamination in comparison to cyclone ash and low co-dissolution of heavy metals (especially Cr, Pb and Ni), while high phosphorus extraction efficiencies (76-86%) were achieved. High Al content in the bottom ash (9.4%) negatively affected the phosphorus extraction efficiency as well as loss on ignition, while the particle size reduction was necessary for ensuring a suitable contact surface. The typology of precipitating agents did not strongly affect the phosphorus precipitation, while pH was the key parameter. At pH 3.5-5, phosphorus precipitation efficiencies higher than 90% were achieved, with a mean phosphorus content in the recovered material equal to 16-17%, comparable to commercial fertilizers. Instead, the co-precipitation of Fe and Al had a detrimental effect on the recovered material, indicating the need for additional treatments

Bio-inspired fabrication of DNA-inorganic hybrid composites using synthetic DNA

Nucleic acid nanostructures have attracted significant interest as potential therapeutic and diagnostic platforms due to their intrinsic biocompatibility and biodegradability, structural and functional diversity, and compatibility with various chemistries for modification and stabilization. Among the fabrication approaches for such structures, the rolling circle techniques have emerged as particularly promising, producing morphologically round, flower-shaped nucleic acid particles: typically hybrid composites of long nucleic acid strands and inorganic magnesium pyrophosphate (Mg2PPi). These constructs are known to form via anisotropic nucleic acid-driven crystallization in a sequence-independent manner, rendering monodisperse and densely packed RNA or DNA–inorganic composites. However, it still remains to fully explore how flexible polymer-like RNA or DNA strands (acting as biomolecular additives) mediate the crystallization process of Mg2PPi and affect the structure and properties of the product crystals. To address this, we closely examined nanoscale details to mesoscopic features of Mg2PPi/DNA hybrid composites fabricated by two approaches, namely rolling circle amplification (RCA)-based in situ synthesis and long synthetic DNA-mediated crystallization. Similar to the DNA constructs fabricated by RCA, the rapid crystallization of Mg2PPi was retarded on a short-range order when we precipitated the crystals in the presence of presynthesized long DNA, which resulted in effective incorporation of biomolecular additives such as DNA and enzymes. These findings further provide a more feasible way to encapsulate bioactive enzymes within DNA constructs compared to in situ RCA-mediated synthesis, i.e., by not only protecting them from possible denaturation under the reaction conditions but also preventing nonselective association of proteins arising from the RCA reaction mixtures

Self-assembled 2D Free-Standing Janus Nanosheets with Single-Layer Thickness

We report the thermodynamically controlled growth of solution-processable and free-standing nanosheets via peptide assembly in two dimensions. By taking advantage of self-sorting between peptide β-strands and hydrocarbon chains, we have demonstrated the formation of Janus 2D structures with single-layer thickness, which enable a predetermined surface heterofunctionalization. A controlled 2D-to-1D morphological transition was achieved by subtly adjusting the intermolecular forces. These nanosheets provide an ideal substrate for the engineering of guest components (e.g., proteins and nanoparticles), where enhanced enzyme activity was observed. We anticipate that sequence-specific programmed peptides will offer promise as design elements for 2D assemblies with face-selective functionalization

Tetrahydro-4H-(pyrrolo[3,4-d]isoxazol-3-yl)methanamine : a bicyclic diamino scaffold stabilizing parallel turn conformations

Tetrahydro-4H-(pyrrolo[3,4-d]isoxazol-3-yl)methanamine scaffold was designed as diamino derivative to stabilize parallel turn conformations. Its synthesis took advantage of a [1,3]-dipolar cycloaddition reaction between the nitrile oxide derived from the inexpensive enantiopure L-phenylalanine, and N-benzyl-3-pyrroline. Two diastereoisomers were formed whose distribution depends on the selected base. 3aR,6aS-Isomer is favoured in organic bases which formation is driven by pi-interactions. On the other hand, the above interactions were significantly prevented using an inorganic base due to the chaotropic effect of the cation, decreasing the amount of the above isomer. Finally, we demonstrated that this isomer is able of stabilizing parallel turn conformations when inserted in short peptide sequences

A Non-coded β2,2-Amino Acid with Isoxazoline Core Able to Stabilize Peptides Folding through an Unprecedented Hydrogen Bond

Dedicated to Prof. Cesare Gennari on the occasion of his 70th birthday New peptidomimetics containing a beta(2,)(2)-isoxazoline amino acid, i.e. 5-(aminomethyl)-3-phenyl-4,5-dihydroisoxazole-5-carboxylic acid (Isox-beta(2,)(2)AA), were prepared and studied by NMR and theoretical calculation. Although similar amino acid derivatives have already been prepared via 1,3-dipolar cycloaddition reaction, neither experimental details nor characterization were found and they were never used for peptide synthesis. Both enantiomers were inserted in peptide sequences to verify their ability to induce a secondary structure. We found that an unexpected conformation is given by R-Isox-beta(2,)(2)AA, inducing the folding of short peptides thanks to an unprecedented H-bond involving C=N of the isoxazoline side chain of our beta(2,)(2)-AA

Tuning PFKFB3 Bisphosphatase Activity Through Allosteric Interference

The human inducible phospho-fructokinase bisphosphatase isoform 3, PFKFB3, is a crucial regulatory node in the cellular metabolism. The enzyme is an important modulator regulating the intracellular fructose-2,6-bisphosphate level. PFKFB3 is a bifunctional enzyme with an exceptionally high kinase to phosphatase ratio around 740:1. Its kinase activity can be directly inhibited by small molecules acting directly on the kinase active site. On the other hand, here we propose an innovative and indirect strategy for the modulation of PFKFB3 activity, achieved through allosteric bisphosphatase activation. A library of small peptides targeting an allosteric site was discovered and synthesized. The binding affinity was evaluated by microscale thermophoresis (MST). Furthermore, a LC-MS/MS analytical method for assessing the bisphosphatase activity of PFKFB3 was developed. The new method was applied for measuring the activation on bisphosphatase activity with the PFKFB3-binding peptides. The molecular mechanical connection between the newly discovered allosteric site to the bisphosphatase activity was also investigated using both experimental and computational methods

Sampling Mechanism for Low Gravity Bodies

In future exploration missions to low gravity bodies (e.g. a Mars moon or a near-Earth asteroid) it is planned to collect more than 100 grams of soil and return them to Earth. In previous studies several sampling tools have been proposed but there is no single sampling technology for low-gravity bodies that has been specifically conceived to provide the ability to collect material in any envisaged situation. Low gravity bodies present indeed peculiar conditions which need to be taken into account during the design and test of sampling and sample handling systems. Primarily, the very reduced gravity limits the thrust reaction capability in support to drilling operations; and, although reactions can be achieved by spacecraft anchoring or by thrust reversal, these operative conditions could limit the effectiveness of the sampling action. An alternative solution is the exploitation of the forces naturally arising from Spacecraft momentum inversion, which can be achieved by ‘touch and go’ techniques (as e.g. performed in Hayabusa mission). Although the small duration of the contact with the soil would anyhow limit the sampling depth and the collectable soil types, a properly designed sampling system would require to conclude the operation with a great effectiveness. In the last three years an ESA founded study has been carried on and a fully functional sampling mechanism for "touch and go" sampling on a low-gravity body has been selected, designed and breadboarded. Based on the results of several Proof-Of-Principle models tested on different types of specimen and after the analysis performed on a dynamic simulation model for the sampling action, a device implementing the most promising sampling technique has been designed and manufactured. It has been then tested under ambient conditions using various kinds of asteroid soil stimulants. The proposed paper will resume the key aspects and the main achievements of the study