Exploring the Relationship between Skeletal Mass and Total Body Mass in Birds

Total body mass (TBM) is known to be related to a number of different osteological features in vertebrates, including limb element measurements and total skeletal mass. The relationship between skeletal mass and TBM in birds has been suggested as a way of estimating the latter in cases where only the skeleton is known (e.g., fossils). This relationship has thus also been applied to other extinct vertebrates, including the non-avian pterosaurs, while other studies have used additional skeletal correlates found in modern birds to estimate TBM. However, most previous studies have used TBM compiled from the literature rather than from direct measurements, producing values from population averages rather than from individuals. Here, we report a new dataset of 487 extant birds encompassing 79 species that have skeletal mass and TBM recorded at the time of collection or preparation. We combine both historical and new data for analyses with phylogenetic control and find a similar and well-correlated relationship between skeletal mass and TBM. Thus, we confirm that TBM and skeletal mass are accurate proxies for estimating one another. We also look at other factors that may have an effect on avian body mass, including sex, ontogenetic stage, and flight mode. While data are well-correlated in all cases, phylogeny is a major control on TBM in birds strongly suggesting that this relationship is not appropriate for estimating the total mass of taxa outside of crown birds, Neornithes (e.g., non-avian dinosaurs, pterosaurs). Data also reveal large variability in both bird skeletal and TBM within single species; caution should thus be applied when using published mass to test direct correlations with skeletal mass and bone lengths.     

Hydroxylamine as a thermal destabiliser of bacteriorhodopsin

The light-catalysed reaction of hydroxylamine (HA) with retinal is one of the basic features of bacteriorhodopsin (BR). Surprisingly, according to recent results, neither the photocycle and proton pumping of BR, nor the trans–cis isomerisation of retinal is prerequisite for photobleaching of BR in the presence of HA. How, then, is the accessibility of retinal to HA enhanced on illumination? We studied whether local thermal denaturation of BR, proposed recently, could provide an explanation for HA-promoted bleaching. According to our results, HA does not alter the absorption spectrum and the photocycle kinetics of BR substantially at room temperature, even at molar concentrations, but grossly affects the temperature of thermal denaturation. At pH 7, the presence of 0.5 M HA reduces the denaturation temperature from 100°C to as low as 72°C. The decrease is proportional to the logarithm of the HA concentration over more than three orders of magnitude, and even 0.5 mM HA has a significant effect. In addition, photobleaching becomes considerably faster with increasing temperature in the presence of HA, it takes a few seconds at 50–60°C. Our results suggest that photobleaching of BR in the presence of HA can be explained by overall destabilisation of the structure of the protein and local thermal denaturation that has already accounted for the photobleaching of the HA-free BR at elevated temperatures. These results further support the importance of thermooptic effects in protein photoreactions and identify HA as a thermal destabiliser of BR.     

The Occurrence of Multidrug-Resistant Pseudomonas aeruginosa on Hydrocarbon-Contaminated Sites

The main aim of this paper was the comprehensive estimation of the occurrence rate and the antibiotic-resistance conditions of opportunistic pathogen Pseudomonas aeruginosa in hydrocarbon-contaminated environments. From 2002 to 2007, 26 hydrocarbon-contaminated sites of Hungary were screened for the detection of environmental isolates. Altogether, 156 samples were collected and examined for the determination of appearance, representative cell counts, and antibiotic-resistance features of P. aeruginosa. The detected levels of minimal inhibitory concentrations of ten different drugs against 36 environmental strains were compared to the results of a widely used reference strain ATCC 27853 and four other clinical isolates of P. aeruginosa. Based on our long-term experiment, it can be established that species P. aeruginosa was detectable in case of 61.5% of the investigated hydrocarbon-contaminated sites and 35.2% of the examined samples that shows its widespread occurrence in polluted soil–groundwater systems. In the course of the antibiotic-resistance assay, our results determined that 11 of the examined 36 environmental strains had multiple drug-resistance against several clinically effective antimicrobial classes: cephalosporins, wide spectrum penicillins, carbapenems, fluoroquinolones, and aminoglycosides. The fact that these multiresistant strains were isolated from 8 different hydrocarbon-contaminated sites, mainly from outskirts, confirms that multiple drug-resistance of P. aeruginosa is widespread not only in clinical, but also in natural surroundings as well.     

Daunomycin-polypeptide conjugates with antitumor activity

We have developed a group of water-soluble drug conjugates in which daunomycin (Dau) is coupled to cationic, amphoteric or anionic branched polypeptides and a new conjugate containing a cationic polypeptide carrier modified with a cell penetrating octaarginine. We investigated in vitro physiological activity of these conjugates in several aspects: in vitro cytotoxicity and cytostatic effect, adhesion and cellular uptake were examined on murine (J774 and L1210) and human (MonoMac6 and HL-60) leukemia cell lines and on murine bone marrow derived macrophages. We found that these processes are dependent on the properties of the carrier, on experimental conditions like concentration and incubation time. We found that attachment of polypeptide and cell penetrating peptide to the bioactive agent, depending on the cell line, could significantly improve the antitumor activity of the drug.     

Collective cell motion in endothelial monolayers

Collective cell motility is an important aspect of several developmental and pathophysiological processes. Despite its importance, the mechanisms that allow cells to be both motile and adhere to one another are poorly understood. In this study we establish statistical properties of the random streaming behavior of endothelial monolayer cultures. To understand the reported empirical findings, we expand the widely used cellular Potts model to include active cell motility. For spontaneous directed motility we assume a positive feedback between cell displacements and cell polarity. The resulting model is studied with computer simulations and is shown to exhibit behavior compatible with experimental findings. In particular, in monolayer cultures both the speed and persistence of cell motion decreases, transient cell chains move together as groups and velocity correlations extend over several cell diameters. As active cell motility is ubiquitous both in vitro and in vivo, our model is expected to be a generally applicable representation of cellular behavior.     

Phenanthrenes and a dihydrophenanthrene from Tamus communis and their cytotoxic activity

From the petroleum ether extract of the rhizomes of Tamus communis, the 7-hydroxy-2,3,4,8-tetramethoxyphenanthrene (1) was isolated, together with the known 2,3,4-trimethoxy-7,8-methylenedioxyphenanthrene (2), 3-hydroxy-2,4,-dimethoxy-7,8-methylenedioxyphenanthrene (3), 2-hydroxy-3,5,7-trimethoxyphenanthrene (4) and 2-hydroxy-3,5,7-trimethoxy-9,10-dihydrophenanthrene (5), through cytotoxic assay guidance. The structures were determined by means of HREIMS, (1)H NMR, JMOD and NOESY experiments. The cytotoxic effects of the isolated compounds were tested on cervix adenocarcinoma (HeLa) cells, with the MTT assay. The results demonstrated that, with the exception of 2, all these compounds displayed pronounced cytotoxic activity; especially 1 and 3 exhibited significant cell growth inhibitory effects, with IC(50)=8.52+/-0.70 and 3.64+/-0.12 microM, respectively.     

The new 2,3-benzodiazepine derivative EGIS-8332 inhibits AMPA/kainate ion channels and cell death

We observed in vitro neuroprotective and AMPA/kainate receptor antagonist effects of the new 2,3-benzodiazepine derivative EGIS-8332 (R,S-1-(4-aminophenyl)-7,8-methylenedioxy-4-cyano-4-methyl-3-N-acetyl-5H-3,4-dihydro-2,3-benzodiazepine) using the lactate dehydrogenase (LDH) release assay and patch clamp recordings on primary cultures of rat embryonic telencephalon neurons exposed to AMPA/kainate receptor agonists. EGIS-8332 potently decreased alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and quisqualate induced LDH release (IC(50)=5.2+/-0.4 and 7.4+/-1.3 microM, respectively) from the cells. Whole-cell patch clamp studies carried out on the ionotropic glutamate receptors N-methyl D-aspartate (NMDA), as well as AMPA (and kainate) in cultured telencephalon neurons verified that EGIS-8332 blocked steady state responses to AMPA and kainate (IC(50)=1.7+/-0.4 and 6.2+/-1.6 microM, respectively), but hardly influenced currents evoked by NMDA. EGIS-8332 also inhibited kainate-evoked response in CHO cells expressing the flop variant of GluR1 receptor and, in cerebellar Purkinje cells at similar efficiency. The stereoselectivity of the inhibitory site is established by the clearly dissimilar inhibitory potency of the enantiomer components of EGIS-8332 differing in the configuration of methyl and cyano substituents on carbon C(4): the R(-) enantiomer was found to be the efficient species. This finding suggests that the inhibitory interaction between the channel protein and drug is promoted by presence of the C(4) methyl group. The inhibition of the AMPA/kainate ion channels by EGIS-8332 is non-competitive, not use dependent, and depends neither on the closed/open state of the channel, nor the membrane potential. These findings suggest an allosteric mechanism for the inhibition. These in vitro observations suggest that the compound might be useful in the treatments of certain acute and chronic neurological syndromes initiated by derangements of ionotropic glutamate receptor function.     

Subchronic heavy metal and alcohol treatment in rats: changes in the somatosensory evoked cortical activity

Young adult male Wistar rats were treated, by gavage, with 80 or 320 mg/kg Pb2+ (lead acetate), 0.4 or 1.6 mg/kg Hg2+ (mercuric chloride) or both by combining the lower doses. For combination with alcohol, ethanol was added to the rats' drinking water in 5 v/v %. After 12 weeks of treatment, electrophysiological recording was made from the somatosensory cortex in urethane anaesthesia. Evoked potentials obtained by stimulation of the whiskers were recorded. Both metals, and alcohol alone, increased significantly the latency of the evoked response. Alcohol seemed to abolish the effect of Pb, but not of Hg. Fatigue, calculated form the response amplitude, was increased by Pb and Hg treatment and this effect of Hg was reduced by ethanol. Evoked activity and its dynamic characteristics were sensitive to the complex neurotoxic effect induced in the rats and can provide a basis for developing functional markers.     

No evidence of genetic benefits from extra-pair fertilisations in female sand martins (Riparia riparia)

Genetic parentage studies of socially monogamous birds reveal a widespread prevalence of extra-pair paternity. Variation in extra-pair paternity among individuals may depend on how different individuals benefit from extra-pair fertilisations and on the opportunity to pursue extra-pair copulations. A long-term study of sand martins (Riparia riparia) in Hungary allowed us to examine patterns of extra-pair fertilisations in a large colony of over 3,000 breeding pairs with many known age individuals. We used multi-locus DNA fingerprinting to determine whether extra-pair fertilisations occur when females are paired to (1) presumably low quality mates, or (2) genetically similar or dissimilar mates, and whether extra-pair fertilisations result in offspring of higher quality. Extra-paternal young were found in 38% of 47 broods and comprised 19% of 190 offspring. Males that lost paternity did not differ significantly from others in age or body condition. Social mates of broods containing extra-pair offspring did not differ in genetic similarity from pairs without extra-pair offspring. Furthermore, there was no significant difference in body condition between extra-pair young and their maternal half-siblings. We were unable to assign paternity and therefore cannot exclude the possibility that extra-pair males differed from the within-pair males they cuckolded, in age, body condition or genetic similarity with the female. We found a positive relationship between paternity losses and breeding density, suggesting that low breeding density may constrain opportunities for seeking extra-pair copulations.