Search results for "cycles"
showing 10 items of 306 documents
Equipping metallo-supramolecular macrocycles with functional groups: Assemblies of pyridine-substituted urea ligands
2012
A series of di-(m-pyridyl)-urea ligands were prepared and characterized with respect to their conformations by NOESY experiments and crystallography. Methyl substitution in different positions of the pyridine rings provides control over the position of the pyridine N atoms relative to the urea carbonyl group. The ligands were used to self-assemble metallo-supramolecular M(2)L(2) and M(3)L(3) macrocycles which are generated in a finely balanced equilibrium in DMSO and DMF according to DOSY NMR experiments and ESI FTICR mass spectrometry. Again, crystallography was used to characterize the assemblies. Methyl substitution in positions next to the pyridine nitrogen prevents coordination, while …
Protonation of a Spherical Macrotricyclic Tetramine: Water Inclusion, Allosteric Effect, and Cooperativity
2017
The spherical macrotricyclic cryptand tetramine "C24" (1) displays remarkable protonation behaviour. It undergoes protonation in four successive steps for which pKa values of 11.17±0.05, 10.28±0.04, 6.00±0.06 and 3.08±0.08 have been determined at 298 K. The unusually close values for the first two protonations provide evidence for the encapsulation of a water molecule serving as effector for the second protonation, which is consistent with earlier observations that the exchange of protons bound in the diprotonated species with solvent protons is unusually slow and that 17 O NMR spectra show the presence of an oxygen centre in the same species quite distinct from that of solvent water. Encap…
Synthesis of 1,3-bis(trimethylcyclam) and 1,3-bis(trimethylcyclen) substituted benzenes
2009
Pd-catalyzed amination of 1,3-dibromobenzene with N,N',N''-trimethylcyclam and N,N',N''-trimethylcyclen provided corresponding 1,3-bis(tetraazamacrocyclic) derivatives of benzene in 25-32% yields. The dependence of the products yields on the phosphine ligand applied (BINAP, DavePHOS) as well as on the stoichiometry of starting compounds was established. Scope and limitations for the synthesis of N-phenyl and N-(3-bromophenyl) derivatives of trimethylcyclam and trimethylcyclen were demonstrated.
Co-infection with iflaviruses influences the insecticidal properties of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies: Implication…
2017
Biological insecticides based on Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) can efficiently control S. exigua larvae on field and greenhouse crops in many parts of the world. Spanish wild populations and laboratory colonies of S. exigua are infected by two iflaviruses (SeIV-1 and SeIV-2). Here we evaluated the effect of iflavirus co-infection on the insecticidal characteristics of SeMNPV occlusion bodies (OBs). Overall, iflavirus co-inoculation consistently reduced median lethal concentrations (LC50) for SeMNPV OBs compared to larvae infected with SeMNPV alone. However, the speed of kill of SeMNPV was similar in the presence or absence of the iflaviruses. A reduction of the we…
The Water to Water Cycles in Microalgae.
2016
In oxygenic photosynthesis, light produces ATP plus NADPH via linear electron transfer, i.e. the in-series activity of the two photosystems: PSI and PSII. This process, however, is thought not to be sufficient to provide enough ATP per NADPH for carbon assimilation in the Calvin-Benson-Bassham cycle. Thus, it is assumed that additional ATP can be generated by alternative electron pathways. These circuits produce an electrochemical proton gradient without NADPH synthesis, and, although they often represent a small proportion of the linear electron flow, they could have a huge importance in optimizing CO2 assimilation. In Viridiplantae, there is a consensus that alternative electron flow comp…
The role of the Strait of Gibraltar in shaping the genetic structure of the Mediterranean Grenadier, Coryphaenoides mediterraneus, between the Atlant…
2017
24 pages, 4 figures, 4 tables, supplementary information https://dx.doi.org/10.1371/journal.pone.0174988.-- Data Availability: The mtDNA COI sequences can be accessed at BOLD systems through the sample ID: ME-9911; ME-11972; ME-13727; GLF011. New mtDNA COI sequences can be accessed at GenBank by the accession numbers KY345206 - KY345398. GenBank accession numbers for close related species of C. mediterraneus are: Coryphaenoides striaturus - KX656427.1, KX656428.1; Coryphaenoides murray - KX656411.1, KX656410.1; Coryphaenoides carapinus - KX656382.1, KX656381.1; Coryphaenoides brevibarbis - KX656377.1, KX656376.1, KX656375.1. An alignment in fasta with all the haplotypes and respective frequ…
Invasive parasites are detectable by their abundance-occupancy relationships: the case of helminths from Liza haematocheilus (Teleostei: Mugilidae)
2018
Abstract The biogeographic patterns of abundance and prevalence of helminths from Liza haematocheilus were studied across its native (Sea of Japan) and introduced (Sea of Azov) distribution ranges. Abundance-occupancy relationships (AORs) were tested for the core-satellite and enemy release (ERH) species hypotheses in eight and 14 host samples from the native and introduced host ranges, respectively. The AOR model fitted parasite data extremely well, irrespective of whether the host or the parasite species were native or invasive. Except for co-introduced monogeneans, species were less abundant and prevalent in the introduced host population than in the native one, which agrees well with th…
Evaluating responses to temperature during pre-metamorphosis and carry-over effects at post-metamorphosis in the wood tiger moth (Arctia plantaginis)
2019
Insect metamorphosis is one of the most recognized processes delimiting transitions between phenotypes. It has been traditionally postulated as an adaptive process decoupling traits between life stages, allowing evolutionary independence of pre- and post-metamorphic phenotypes. However, the degree of autonomy between these life stages varies depending on the species and has not been studied in detail over multiple traits simultaneously. Here, we reared full-sib larvae of the warningly coloured wood tiger moth ( Arctia plantaginis ) in different temperatures and examined their responses for phenotypic (melanization change, number of moults), gene expression (RNA-seq and qPCR of candidate ge…
Predator–vole interactions in northern Europe: the role of small mustelids revised
2014
The cyclic population dynamics of vole and predator communities is a key phenomenon in northern ecosystems, and it appears to be influenced by climate change. Reports of collapsing rodent cycles have attributed the changes to warmer winters, which weaken the interaction between voles and their specialist subnivean predators. Using population data collected throughout Finland during 1986–2011, we analyse the spatio-temporal variation in the interactions between populations of voles and specialist, generalist and avian predators, and investigate by simulations the roles of the different predators in the vole cycle. We test the hypothesis that vole population cyclicity is dependent on predator…
Voles and weasels in the boreal Fennoscandian small mammal community : What happens if the least weasel disappears due to climate change?
2019
Climate change, habitat loss and fragmentation are major threats for populations and a challenge for individual behavior, interactions and survival. Predator–prey interactions are modified by climate processes. In the northern latitudes, strong seasonality is changing and the main predicted feature is shortening and instability of winter. Vole populations in the boreal Fennoscandia exhibit multiannual cycles. High amplitude peak numbers of voles and dramatic population lows alternate in 3–5‐year cycles shortening from North to South. One key factor, or driver, promoting the population crash and causing extreme extended lows, is suggested to be predation by the least weasel. We review the ar…