Phylogeny, Life History Evolution and Biogeography of the Rhinanthoid Orobanchaceae

Rhinanthoid Orobanchaceae form a monophyletic lineage that include the hemiparasitic genera Euphrasia, Melampyrum, Tozzia, Bartsia, Nothobartsia, Odontites (s.l.), Rhinanthus, Rhynchocorys, Parentucellia, Hedbergia and holoparasitic Lathraea. In this study, we aimed to reconstruct the phylogeny, evolution of life-history traits (life cycle and seed size) and explain the extant biogeographical patterns in this group. For phylogenetic reconstruction, we used molecular data obtained by sequencing the nuclear ITS region and the chloroplast trnT-trnL intergenic spacer and matK?+?trnK regions. The genus Melampyrum was found to occupy the sister position to the rest of the group. The other genera were assembled in the sister Rhinanthus-Rhynchocorys-Lathraea and Bartsia-Euphrasia-Odontites subclades. The reconstruction of life-cycle evolution yielded ambiguous results suggesting nonetheless a substantially higher likelihood of perenniality compared to annuality in most ancestor lineages. Seed size varied across two orders of magnitude (average weight per seed: 0.02–7.22 mg) and tended to decrease in the Bartsia-Euphrasia-Odontites subclade compared to the rest of the group. Seed-size evolution was correlated with life-history evolution in the group if the generally small-seeded Bartsia-Euphrasia-Odontites subclade is excluded. We formulated hypotheses relating the extant biogeographical affinities of individual genera to the geological history of the Euro-Caucasian diversity center of the group. Notable dispersal events in Euphrasia and Bartsia were hypothesized to be allowed or at least facilitated by a specific combination of the life-history traits.     

Analysis of extra‐pair paternity and conspecific brood parasitism in mallards Anas platyrhynchos using non‐invasive techniques

A method that was based on non‐invasive sampling of genetic material was used to determine the rates of extra‐pair paternity (EPP) and conspecific brood parasitism (CBP) in mallards. Maternal and offspring DNA were extracted from feathers in nest material and hatched eggshell membranes. Using 8 microsatelite loci, extra‐pair offspring were detected in 48% of nests and accounted for 9.3% of all offspring. In addition, 10.1% of the offspring were confirmed to result from CBP, and 24% of all nests contained at least 1 offspring from CBP. Rates of conspecific nest parasitism were higher than those of related species, which might have been due to higher breeding densities at our study site. The incidence of EPP was distributed randomly (i.e. did not deviate from bionomial distribution) throughout the population, indicating that variations in pre‐copulatory (e.g. female choice, mate guarding) or post‐copulatory processes (e.g. sperm competition, cryptic female choice) do not affect the distribution of EPP among breeding pairs markedly. Yet, our data provide evidence of variation in the risk of being parasitized among breeding females. The occurrence of CBP and EPP was unaffected by the timing of the breeding attempt or breeding synchrony.     

Novel antimicrobial peptides from the venom of the eusocial bee Halictus sexcinctus (Hymenoptera: Halictidae) and their analogs

Two novel antimicrobial peptides, named halictines, were isolated from the venom of the eusocial bee Halictus sexcinctus. Their primary sequences were established by ESI-QTOF mass spectrometry, Edman degradation and enzymatic digestion as Gly-Met-Trp-Ser-Lys-Ile-Leu-Gly-His-Leu-Ile-Arg-NH₂ (HAL-1), and Gly-Lys-Trp-Met-Ser-Leu-Leu-Lys–His-Ile-Leu-Lys-NH₂ (HAL-2). Both peptides exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria but also noticeable hemolytic activity. The CD spectra of HAL-1 and HAL-2 measured in the presence of trifluoroethanol or SDS showed ability to form an amphipathic α-helical secondary structure in an anisotropic environment such as bacterial cell membrane. NMR spectra of HAL-1 and HAL-2 measured in trifluoroethanol/water confirmed formation of helical conformation in both peptides with a slightly higher helical propensity in HAL-1. Altogether, we prepared 51 of HAL-1 and HAL-2 analogs to study the effect of such structural parameters as cationicity, hydrophobicity, α-helicity, amphipathicity, and truncation on antimicrobial and hemolytic activities. The potentially most promising analogs in both series are those with increased net positive charge, in which the suitable amino acid residues were replaced by Lys. This improvement basically relates to the increase of antimicrobial activity against pathogenic Pseudomonas aeruginosa and to the mitigation of hemolytic activity.     

Signal/noise analysis of FRET-based sensors

Molecular sensors based on intramolecular Förster resonance energy transfer (FRET) have become versatile tools to monitor regulatory molecules in living tissue. However, their use is often compromised by low signal strength and excessive noise. We analyzed signal/noise (SNR) aspects of spectral FRET analysis methods, with the following conclusions: The most commonly used method (measurement of the emission ratio after a single short wavelength excitation) is optimal in terms of signal/noise, if only relative changes of this uncalibrated ratio are of interest. In the case that quantitative data on FRET efficiencies are required, these can be calculated from the emission ratio and some calibration parameters, but at reduced SNR. Lux-FRET, a recently described method for spectral analysis of FRET data, allows one to do so in three different ways, each based on a ratio of two out of three measured fluorescence signals (the donor and acceptor signal during a short-wavelength excitation and the acceptor signal during long wavelength excitation). Lux-FRET also allows for calculation of the total abundance of donor and acceptor fluorophores. The SNR for all these quantities is lower than that of the plain emission ratio due to unfavorable error propagation. However, if ligand concentration is calculated either from lux-FRET values or else, after its calibration, from the emission ratio, SNR for both analysis modes is very similar. Likewise, SNR values are similar, if the noise of these quantities is related to the expected dynamic range. We demonstrate these relationships based on data from an Epac-based cAMP sensor and discuss how the SNR changes with the FRET efficiency and the number of photons collected.     

Comparative analysis of cis-regulation following stroke and seizures in subspaces of conserved eigensystems

Background  

It is often desirable to separate effects of different regulators on gene expression, or to identify effects of the same regulator across several systems. Here, we focus on the rat brain following stroke or seizures, and demonstrate how the two tasks can be approached simultaneously.     

Correlated evolution of LTR retrotransposons and genome size in the genus <Emphasis Type="Italic">eleocharis</Emphasis>

Background  

Transposable elements (TEs) are considered to be an important source of genome size variation and genetic and phenotypic plasticity in eukaryotes. Most of our knowledge about TEs comes from large genomic projects and studies focused on model organisms. However, TE dynamics among related taxa from natural populations and the role of TEs at the species or supra-species level, where genome size and karyotype evolution are modulated in concert with polyploidy and chromosomal rearrangements, remain poorly understood. We focused on the holokinetic genus Eleocharis (Cyperaceae), which displays large variation in genome size and the occurrence of polyploidy and agmatoploidy/symploidy. We analyzed and quantified the long terminal repeat (LTR) retrotransposons Ty1-copia and Ty3-gypsy in relation to changes in both genome size and karyotype in Eleocharis. We also examined how this relationship is reflected in the phylogeny of Eleocharis.     

Interaction of AT1 receptors and V1a receptors-mediated effects in the central cardiovascular control during the post-infarct state

Experimental objectives. Because myocardial infarct is associated with overactivation of brain angiotensin II (ANG II) and vasopressin (AVP) V1a receptors we decided to determine whether AT1 and V1a receptors-mediated effects of ANG II and AVP interact in central cardiovascular control during the post-infarct state. Four groups of infarcted and four groups of sham-operated conscious rats entered the study. Results. In the infarcted rats cerebroventricular infusion of AT1 (AT1ANT, losartan) and V1a antagonist {V1aANT,d(CH(2))(5)[Tyr(Me)(2)Ala-NH(2)(9)]VP} and combined infusion of both these compounds performed 4 weeks after induction of the infarct significantly and comparably reduced mean arterial blood pressure (MABP) in comparison to control experiments (artificial cerebrospinal fluid infusion). In the sham rats MABP was not affected by any of the infusions. In control experiments MABP and HR responses to an alarming air jet stress were significantly higher in the infarcted than in the sham rats. Both responses were normalized with the same effectiveness by administration of AT1ANT, V1aANT and AT1ANT+V1aANT. In the sham rats administration of these compounds did not affect MABP and HR responses to stress. Conclusion: The results provide evidence for interaction of AT1 and V1a receptors-mediated effects of ANG II and AVP in the central cardiovascular control during the post-infarct state.     

Classical anticytokinins do not interact with cytokinin receptors but inhibit cyclin-dependent kinases

Cytokinins are a class of plant hormones that regulate the cell cycle and diverse developmental and physiological processes. Several compounds have been identified that antagonize the effects of cytokinins. Based on structural similarities and competitive inhibition, it has been assumed that these anticytokinins act through a common cellular target, namely the cytokinin receptor. Here, we examined directly the possibility that various representative classical anticytokinins inhibit the Arabidopsis cytokinin receptors CRE1/AHK4 (cytokinin response 1/Arabidopsis histidine kinase 4) and AHK3 (Arabidopsis histidine kinase 3). We show that pyrrolo[2,3-d]pyrimidine and pyrazolo[4,3-d]pyrimidine anticytokinins do not act as competitors of cytokinins at the receptor level. Flow cytometry and microscopic analyses revealed that anticytokinins inhibit the cell cycle and cause disorganization of the microtubular cytoskeleton and apoptosis. This is consistent with the hypothesis that they inhibit regulatory cyclin-dependent kinase (CDK) enzymes. Biochemical studies demonstrated inhibition by selected anti-cytokinins of both Arabidopsis and human CDKs. X-ray determination of the crystal structure of a human CDK2-anticytokinin complex demonstrated that the antagonist occupies the ATP-binding site of CDK2. Finally, treatment of human cancer cell lines with anticytokinins demonstrated their ability to kill human cells with similar effectiveness as known CDK inhibitors.