Insertion mutations at the maizeOpaque2 locus induced by transposable element familiesAc, En/Spm andBg

Eight independently isolated unstable alleles of theOpaque2 (O2) locus were analysed genetically and at the DNA level. The whole series of mutations was isolated from a maize strain carrying a wild-typeO2 allele and the transposable elementActivator (Ac) at thewx-m7 allele. Previous work with another unstable allele of the same series has shown that it was indeed caused by the insertion of anAc element. Unexpectedly, the remaining eight mutations were not caused by the designatedAc element, but by other insertions that are structurally similar or identical to one of two different autonomous transposable elements. Six mutations were caused by the insertion of a transposable element of theEnhancer/Suppressor-Mutator (En/Spm) family. Two mutations were the result of the insertion of a transposable element of theBergamo (Bg) family. Genetic tests carried out with plants carrying the unstable mutations demonstrated that all were caused by the insertion of an autonomous transposable element.     

Cyclic biphalin analogues with a novel linker lead to potent agonist activities at mu,delta, and kappa opioid receptors

In an effort to improve biphalin’s potency and efficacy at the µ-(MOR) and δ-opioid receptors (DOR), a series of cyclic biphalin analogues 1–5 with a cystamine or piperazine linker at the C-terminus were designed and synthesized by solution phase synthesis using Boc-chemistry. Interestingly, all of the analogues showed balanced opioid agonist activities at all opioid receptor subtypes due to enhanced κ-opioid receptor (KOR) activity. Our results indicate that C-terminal flexible linkers play an important role in KOR activity compared to that of the other cyclic biphalin analogues with a hydrazine linker. Among them, analogue 5 is a potent (Ki?=?0.27, 0.46, and 0.87?nM; EC₅₀?=?3.47, 1.45, and 13.5?nM at MOR, DOR, and KOR, respectively) opioid agonist with high efficacy. Based on the high potency and efficacy at the three opioid receptor subtypes, the ligand is expected to have a potential synergistic effect on relieving pain and further studies including in vivo tests are worthwhile.     

A long winter for the Red Queen: rethinking the evolution of seasonal migration

This paper advances an hypothesis that the primary adaptive driver of seasonal migration is maintenance of site fidelity to familiar breeding locations. We argue that seasonal migration is therefore principally an adaptation for geographic persistence when confronted with seasonality – analogous to hibernation, freeze tolerance, or other organismal adaptations to cyclically fluctuating environments. These ideas stand in contrast to traditional views that bird migration evolved as an adaptive dispersal strategy for exploiting new breeding areas and avoiding competitors. Our synthesis is supported by a large body of research on avian breeding biology that demonstrates the reproductive benefits of breeding‐site fidelity. Conceptualizing migration as an adaptation for persistence places new emphasis on understanding the evolutionary trade‐offs between migratory behaviour and other adaptations to fluctuating environments both within and across species. Seasonality‐induced departures from breeding areas, coupled with the reproductive benefits of maintaining breeding‐site fidelity, also provide a mechanism for explaining the evolution of migration that is agnostic to the geographic origin of migratory lineages (i.e. temperate or tropical). Thus, our framework reconciles much of the conflict in previous research on the historical biogeography of migratory species. Although migratory behaviour and geographic range change fluidly and rapidly in many populations, we argue that the loss of plasticity for migration via canalization is an overlooked aspect of the evolutionary dynamics of migration and helps explain the idiosyncratic distributions and migratory routes of long‐distance migrants. Our synthesis, which revolves around the insight that migratory organisms travel long distances simply to stay in the same place, provides a necessary evolutionary context for understanding historical biogeographic patterns in migratory lineages as well as the ecological dynamics of migratory connectivity between breeding and non‐breeding locations.     

8,000 years of climate,vegetation, fire and land-use dynamics in the thermo-mediterranean vegetation belt of northern Sardinia (Italy)

Vegetation History and Archaeobotany - Knowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record...     

Donor–Acceptor Shape Matching Drives Performance in Photovoltaics

While the demonstrated power conversion efficiency of organic photovoltaics (OPVs) now exceeds 10%, new design rules are required to tailor interfaces at the molecular level for optimal exciton dissociation and charge transport in higher efficiency devices. We show that molecular shape‐complementarity between donors and acceptors can drive performance in OPV devices. Using core hole clock (CHC) X‐ray spectroscopy and density functional theory (DFT), we compare the electronic coupling, assembly, and charge transfer rates at the interface between C₆₀ acceptors and flat‐ or contorted‐hexabenzocorone (HBC) donors. The HBC donors have similar optoelectronic properties but differ in molecular contortion and shape matching to the fullerene acceptors. We show that shape‐complementarity drives self‐assembly of an intermixed morphology with a donor/acceptor (D/A) ball‐and‐socket interface, which enables faster electron transfer from HBC to C₆₀. The supramolecular assembly and faster electron transfer rates in the shape complementary heterojunction lead to a larger active volume and enhanced exciton dissociation rate. This work provides fundamental mechanistic insights on the improved efficiency of organic photovoltaic devices that incorporate these concave/convex D/A materials.     

Characterization of C2C12 cells in simulated microgravity: Possible use for myoblast regeneration

Muscle loss is a major problem for many in lifetime. Muscle and bone degeneration has also been observed in individuals exposed to microgravity and in unloading conditions. C2C12 myoblst cells are able to form myotubes, and myofibers and these cells have been employed for muscle regeneration purposes and in myogenic regeneration and transplantation studies. We exposed C2C12 cells in an random position machine to simulate microgravity and study the energy and the biochemical challenges associated with this treatment. Simulated microgravity exposed C2C12 cells maintain positive proliferation indices and delay the differentiation process for several days. On the other hand this treatment significantly alters many of the biochemical and the metabolic characteristics of the cell cultures including calcium homeostasis. Recent data have shown that these perturbations are due to the inhibition of the ryanodine receptors on the membranes of intracellular calcium stores. We were able to reverse this perturbations treating cells with thapsigargin which prevents the segregation of intracellular calcium ions in the mitochondria and in the sarco/endoplasmic reticula. Calcium homeostasis appear a key target of microgravity exposure. In conclusion, in this study we reported some of the effects induced by the exposure of C2C12 cell cultures to simulated microgravity. The promising information obtained is of fundamental importance in the hope to employ this protocol in the field of regenerative medicine     

11 Findings and hurdles on the path leading from formamide to the spontaneous generation of RNA

Our laboratories analyze the synthetic reactions leading from formamide, NH₂COH to prebiotically relevant compounds in the presence of catalysts. We have described the formation of all the biological nucleic bases of carboxylic acids of two aminoacids, and of condensing agents in the presence of catalysts of terrestrial origin (Saladino et al., 2012) and of one meteorite. Heat-dependent synthetic reactions from NH₂COH lead to the synthesis of acyclonucleosides, not (yet?) to that of nucleosides [hurdle # 1]. Nucleosides are phosphorylated in the presence of NH₂COH and a phosphate source yielding cyclic nucleotides as well. (Costanzo et al., 2007). 3′,5′-cyclic GMP nonenzymatically polymerizes up to at least 25mers, as shown by PAGE, MALDI ToF, ³¹P-NMR, specific RNAse and inhibitors analyses (Costanzo et al., 2012).The reaction is stimulated by 1,8-diazabicycloundec-7-ene and dimethylformamide. 3′,5′-cUMP does not polymerize spontaneously [hurdle # 2], 3′,5′-cAMP polymerizes very poorly [hurdle # 3]. We will discuss data on the polymerization of 3′,5′-cCMP and on a ribozyme activity exerted by oligomers neosynthesized from cyclic nucleotides. This approach finds its larger perspective in the evolutionary scenario depicted by Trifonov (2009).