Oxygen and Reperfusion Damage: an Overview

Reperfusion of the ischaemic myocardium is associated with a number of oxygen dependent processes which can damage cells. The role of oxidants in mediating reperfusion damage will be discussed.     

Clusterings should not be compared by visual inspection: response to Gagné & Proulx

In Heikinheimo et al . ( Journal of Biogeography , 2007, 34 , 1053–1064) we used clustering to analyse European land mammal fauna. Gagné & Proulx criticized our choice of the Euclidean distance measure in the analysis, and advocated the use of the Hellinger distance measure, claiming that this leads to very different clustering results. The criticism fails to take into account the probabilistic nature of the methods used and the fact that in this case the similarity measures correlate strongly. Gagné & Proulx used subjective inspection as the criterion of similarity between clusterings. We show that this is insufficient and misleading. Namely, owing to the local minimum problem, two clustering runs rarely give identical results. In the case of our study, the measured similarity (using the kappa statistic) between the Euclidean- and Hellinger-based clusterings is roughly equal to the similarity between two clusterings that both use the Hellinger distance but different random initialization points.     

A Model of Genome Size Dynamics During Speciation

A model developed for the evolving size of the repetitive part of the eukaryote genome during speciation was subjected to analytical and computer treatment. The basic assumption of the model was that two classes of repetitive DNA contribute mainly to macroevolutionary changes in genome size: arrays of tandem repeats (ATR) changing through unequal crossover and mobile genetic elements (MGE) changing presumably through an integration mechanism of the Tn- and Is-kind operating in bacteria. Within the framework of this model, the macroevolution of the MGE size is formally equivalent to that of the ATR in the particular case when shifts of chromatids have only one repeat out of register. This allowed us to consider genome size as a large set of various ATRs. The results obtained are as follows. If the duplication and deletion of repeats have unequal fixation probabilities during each speciation act, the predicted species distributions of genome size significantly deviate from the real ones; if they have equal fixation probabilities, there is a conformance between calculated and real distributions. In the latter case, the model reproduces the salient features of real distributions upon acceptance of 1) upper selective boundary nonspecifically limiting increase in genome size within the evolving taxonomic group and 2) non-neutrality of variability in genome size with respect to speciation.     

Restoring Remote Ecosystems

Indirect effects from climate‐driven changes in ecosystems that are remote from direct human activity pose challenges for ecological restoration. Significant and often indirect impacts on alpine ecosystems, the primary ecosystem under consideration in this article, threaten historical‐reference conditions and the viability of some species. The impetus for restoration is similar to projects involving more direct and proximate impacts, but the issues are more complicated in remote ecosystems. Restoration efforts in remote ecosystems might do more harm than good, and the effort required for effective restoration might be greater than easily justified given the shortfall of resources for restoring more heavily impacted ecosystems. The long duration and integration of impacts on remote landscapes pose a distinct set of challenges to restorationists. Intervening in remote ecosystems makes them less remote by definition (they are now affected by human agency). In this article, we examine scientific, technical, and moral issues and offer an initial model for assessing the appropriateness of restoring remote landscapes.     

Influence of most reactive inorganic cation in the optical and biological activities of L-Lysine monohydrochloride crystal

Slow evaporation method was used to grow the pure and K⁺ ion doped L-Lysine monohydrochloride (L-LMHCL) crystals which has optical and antibiotic applications. The space group, structure and slight shifting of peaks are confirmed using single crystal XRD and the powder XRD. The FTIR analysis also shows that the K⁺ doped L-LMHCL has a slight shifting in the spectrum which indicates the functional group of L-LMHCL and the interaction between the K⁺ ions. The existence of K⁺ ion in the doped crystal is assured by the presence of potassium in the EDAX spectrum. The wide optical band gap was found for pure and K⁺ doped crystal using UV spectra and these are utilized in optoelectronic and nonlinear applications. The Kurtz Perry technique specified the NLO property of grown crystals. The dielectric property crystals was studied by varying the temperature. As a result, the highest dielectric constant is observed in doped crystal. An antibacterial activity against certain bacteria like E-coli, pseudomonas aeruginosa and staphylococcus aureus are provided by mm range for the grown crystals.     

Offspring phenotype is shaped by the nonsperm fraction of semen

In a large majority of animal species, the only contribution of males to the next generation has been assumed to be their genes (sperm). However, along with sperm, seminal plasma contains a wide array of extracellular factors that have many important functions in reproduction. Yet, the potential intergenerational effects of these factors are virtually unknown. We investigated these effects in European whitefish (Coregonus lavaretus) by experimentally manipulating the presence and identity of seminal plasma and by fertilizing the eggs of multiple females with the manipulated and unmanipulated semen of several males in a full‐factorial breeding design. The presence of both own seminal plasma and foreign seminal plasma inhibited sperm motility, and the removal of own seminal plasma decreased embryo survival. Embryos hatched significantly earlier after both semen manipulations than in control fertilizations; foreign seminal plasma also increased offspring aerobic swimming performance. Given that our experimental design allowed us to control potentially confounding sperm‐mediated (sire) effects and maternal effects, our results indicate that seminal plasma may have direct intergenerational consequences for offspring phenotype and performance. This novel source of offspring phenotypic variance may provide new insights into the evolution of polyandry and mechanisms that maintain heritable variation in fitness and associated female mating preferences.     

Mate choice for nonadditive genetic benefits and the maintenance of genetic diversity in song sparrows

The lek paradox asserts that strong directional selection via female choice should deplete additive genetic variation in fitness and consequently any benefit to females expressing the preference. Recently, we have provided a novel resolution to the paradox by showing that nonadditive genetic effects such as overdominance can be inherited from parent to offspring, and populations with females that express a mating preference for outbred males maintain higher genetic variation than populations with females that mate randomly. Here, we test our dynamic model using empirical data previously published from a small island population of song sparrows (Melospiza melodia). The model assumes that fitness and male trait expression display overdominance effects. The results demonstrate that female choice for outbred males mediated by directional selection on song repertoire size provides a heritable benefit to offspring through reduced inbreeding depression. Within the population, we estimate the heritability of the inbreeding coefficient to be 0.18 ± 0.08 (SD). Furthermore, we show that mate choice for outbred males increases fitness‐related genetic variation in the population by 12% and thereby reduces inbreeding depression by 1% per generation in typical years and upwards of 15% in severe years. Thus, mate choice may help to stave off population extinction in this and other small populations.     

Rapid evolution of social learning

Culture is widely thought to be beneficial when social learning is less costly than individual learning and thus may explain the enormous ecological success of humans. Rogers (1988. Does biology constrain culture. Am. Anthropol.  90 : 819–831) contradicted this common view by showing that the evolution of social learning does not necessarily increase the net benefits of learned behaviours in a variable environment. Using simulation experiments, we re‐analysed extensions of Rogers’ model after relaxing the assumption that genetic evolution is much slower than cultural evolution. Our results show that this assumption is crucial for Rogers’ finding. For many parameter settings, genetic and cultural evolution occur on the same time scale, and feedback effects between genetic and cultural dynamics increase the net benefits. Thus, by avoiding the costs of individual learning, social learning can increase ecological success. Furthermore, we found that rapid evolution can limit the evolution of complex social learning strategies, which have been proposed to be widespread in animals.