Olfactory discrimination: when vision matters?

Many previous studies have attempted to investigate the effect of visual cues on olfactory perception in humans. The majority of this research has only looked at the modulatory effect of color, which has typically been explained in terms of multisensory perceptual interactions. However, such crossmodal effects may equally well relate to interactions taking place at a higher level of information processing as well. In fact, it is well-known that semantic knowledge can have a substantial effect on people's olfactory perception. In the present study, we therefore investigated the influence of visual cues, consisting of color patches and/or shapes, on people's olfactory discrimination performance. Participants had to make speeded odor discrimination responses (lemon vs. strawberry) while viewing a red or yellow color patch, an outline drawing of a strawberry or lemon, or a combination of these color and shape cues. Even though participants were instructed to ignore the visual stimuli, our results demonstrate that the accuracy of their odor discrimination responses was influenced by visual distractors. This result shows that both color and shape information are taken into account during speeded olfactory discrimination, even when such information is completely task irrelevant, hinting at the automaticity of such higher level visual-olfactory crossmodal interactions.     

Where and when the earliest coccolithophores?

Gardin, S., Krystyn, L., Richoz, S., Bartolini, A. & Galbrun, B. 2012: Where and when the earliest coccolithophores? Lethaia, Vol. 45, pp. 507–523. New calcareous nannofossil analyses from the Northern Calcareous Alps of Austria are herein used to update and improve the state of knowledge about the oldest occurrence of coccolithophores reported in the literature. Previously reported Norian occurrences of coccoliths were based on an obsolete Triassic chronostratigraphy, in which the Rhaetian stage was subsumed into the Norian (‘Sevatian 2’). The oldest stratigraphical record of coccoliths spp. lies just below the Norian‐Rhaetian boundary and the first coccolith species, Crucirhabdus minutus, is recorded from the base of Rhaetian stage. The latter bio‐event is located just above the First Occurrence of the conodont Misikella posthersteni and the first occurrence of the ammonoid Paracochloceras suessi in the Steinbergkogel section (Austria), Global Stratotype Section and Point (GSSP) candidate for the Norian–Rhaetian boundary. The appearance of the coccolith Crucirhabdus minutus is seen as a robust biochronological datum that will provide useful constraints for Triassic biostratigraphy, palaeoclimatic modelling and phylogenetic reconstructions. The new calcareous nannofossil biochronology of Steinbergkogel that we present herein completes the existing biostratigraphic characterization of the Norian‐Rhaetian transition based on conodonts and ammonoids and strengthens the position of Steinbergkogel as the best GSSP proposed section for the base of the Rhaetian. The record of coccolithophores across the Norian–Rhaetian boundary at Steinbergkogel takes place along with a discernible increase in abundance of Prinsiosphaera triassica, as well as the appearance of Euconusphaera zlambachensis, which are the two most important Rhaetian pelagic carbonate producers. This succession of bio‐events is interpreted as the initiation of the pelagic carbonate production driven by the successful spreading of calcareous nannofossils in the Western Tethys during the Rhaetian. □Austria, Calcareous Alps, coccolithophores, Triassic.     

Sympatric speciation: when is it possible?

This paper is written to compare the results of theoretical investigations of sympatric speciation with the relevant experimental data. We understand sympatric speciation as a formation of species out of a population whose spatial structure is not important genetically. A necessary prerequisite for speciation is an action of disruptive selection on sufficiently polymorphic traits. The present analysis confirms the view that such a selection is ecologically realistic. The genetical part of speciation begins with a development of reproductive isolation between those individuals that are opposed in some characters. It is shown that selection for reproductive isolation may be quite strong. Extinction of intermediate individuals, which completes speciation, proceeds under a wide range of conditions, including those when the newly formed species differ in quantitative characters, though most of the genes arc likely to remain the same in both species. The whole process seems possible if differences in several (up to 10) loci are sufficient to adapt the forming species to different niches and to establish reproductive isolation. It is shown that populations with bimodal distributions of some genetically determined quantitative characters can have a considerable life-time. Such distributions may be formed either as a transition stage of sympatric speciation or represent a stationary state under conditions close to those necessary to complete speciation. They are very important for experimental investigations. Sympatric speciation always follows the same principal course; it does not contradict the idea of a genome coadaptedness. The occurrence of sympatric speciation is different for different taxa depending rather on how frequently populations are subjected to the appropriate kind of selection than on their ability to obey it.     

To spike,or when to spike?

Recent experimental reports have suggested that cortical networks can operate in regimes were sensory information is encoded by relatively small populations of spikes and their precise relative timing. Combined with the discovery of spike timing dependent plasticity, these findings have sparked growing interest in the capabilities of neurons to encode and decode spike timing based neural representations. To address these questions, a novel family of methodologically diverse supervised learning algorithms for spiking neuron models has been developed. These models have demonstrated the high capacity of simple neural architectures to operate also beyond the regime of the well established independent rate codes and to utilize theoretical advantages of spike timing as an additional coding dimension.     

Community assembly: when should history matter?

Community assembly provides a conceptual foundation for understanding the processes that determine which and how many species live in a particular locality. Evidence suggests that community assembly often leads to a single stable equilibrium, such that the conditions of the environment and interspecific interactions determine which species will exist there. In such cases, regions of local communities with similar environmental conditions should have similar community composition. Other evidence suggests that community assembly can lead to multiple stable equilibria. Thus, the resulting community depends on the assembly history, even when all species have access to the community. In these cases, a region of local communities with similar environmental conditions can be very dissimilar in their community composition. Both regional and local factors should determine the patterns by which communities assemble, and the resultant degree of similarity or dissimilarity among localities with similar environments. A single equilibrium in more likely to be realized in systems with small regional species pools, high rates of connectance, low productivity and high disturbance. Multiple stable equilibria are more likely in systems with large regional species pools, low rates of connectance, high productivity and low disturbance. I illustrate preliminary evidence for these predictions from an observational study of small pond communities, and show important effects on community similarity, as well as on local and regional species richness.     

Apoptosis in the heart: when and why?

Since mammalian cardiac myocytes essentially rely on aerobic energy metabolism, it has been assumed that cardiocytes die in a catastrophic breakdown of cellular homeostasis (i.e. necrosis), if oxygen supply remains below a critical limit. Recent observations, however, indicate that a process of gene-directed cellular suicide (i.e. apoptosis) is activated in terminally differentiated cardiocytes of the adult mammalian heart by ischemia and reperfusion, and by cardiac overload as well. Apoptosis or programmed cell death is an actively regulated process of cellular self destruction, which requires energy and de novo gene expression, and which is directed by an inborn genetic program. The final result of this program is the fragmentation of nuclear DNA into typical nucleosomal ladders, while the functional integrity of the cell membrane and of other cellular organelles is still maintained. The critical step in this regulated apoptotic DNA fragmentation is the proteolytic inactivation of poly-[ADPribose]-polymerase (PARP) by a group of cysteine proteases with some structural homologies to interleukin-1-converting enzyme (ICE-related proteases [IRPs] such as apopain, yama and others). PARP catalyzes the ADP-ribosylation of nuclear proteins at the sites of spontaneous DNA strand breaks and thereby facilitates the repair of this DNA damage. IRP-mediated destruction of PARP, the supervisor of the genome, can be induced by activation of membrane receptors (e.g. FAS or APOI) and other signals, and is inhibited by activation of anti-death genes (e.g. bcl-2). Overload-triggered myocyte apoptosis appears to contribute to the transition to cardiac failure, which can be prevented by therapeutic hemodynamic unloading. In myocardial ischemia, the activation of the apoptotic program in cardiocytes does not exclude their final destiny to catastrophic necrosis with release of cytosolic enzymes, but might be considered as an adaptive process in hypoperfused ventricular zones, sacrificing some jeopardized myocytes to regulated apoptosis, which may by less arrhythmogenic than necrosis with the primary disturbance of membrane function.     

Lateral gene transfer: when will adolescence end?

The scope and impact of horizontal gene transfer (HGT) in Bacteria and Archaea has grown from a topic largely ignored by the microbiological community to a hot-button issue gaining staunch supporters (on particular points of view) at a seemingly ever-increasing rate. Opinions range from HGT being a phenomenon with minor impact on overall microbial evolution and diversification to HGT being so rampant as to obfuscate any opportunities for elucidating microbial evolution - especially organismal phylogeny - from sequence comparisons. This contentious issue has been fuelled by the influx of complete genome sequences, which has allowed for a more detailed examination of this question than previously afforded. We propose that the lack of common ground upon which to formulate consensus viewpoints probably stems from the absence of answers to four critical questions. If addressed, they could clarify concepts, reject tenuous speculation and solidify a robust foundation for the integration of HGT into a framework for long-term microbial evolution, regardless of the intellectual camp in which you reside. Here, we examine these issues, why their answers shape the outcome of this debate and the progress being made to address them.     

Do house mice use UV cues when foraging?

Research on the behavioural ecology of ultraviolet (UV-A, wavelengths of 320–400 nm, hereafter: UV) sensitivity in terrestrial vertebrates has mainly focused on sexual signalling and foraging in birds and reptiles, whereas the fact that some rodents are also sensitive to UV light has been somewhat ignored. Here, we present the results of two behavioural experiments, which tested whether rodents use UV cues in foraging. In the first experiment we asked whether the colour contrast in the UV waveband is used as a foraging cue. House mice were offered UV-reflecting and UV-absorbing artificial food items in two different illuminations where UV light was either present or absent. The food items were offered to two groups of mice, one group on a UV-reflecting and the other on a UV-absorbing background. The second experiment investigated more specifically whether UV cues are especially important in dawn and dusk when short wavelengths are high in the proportion of available light. House mice showed no preference between the food items regardless of illumination or background. Therefore, our results indicate that house mice do not use UV cues in foraging.     

Does sleep really shorten when we get older?

Sleep and Biological Rhythms -     

Iron homeostasis in plants： when transcription affects translocation

Despite the fact that iron is one of the most abundant elements of the earth＇s crust, iron deficiencies are serious problems both in human nutrition [ 1 ] and in agriculture [2]. Six to eight percent of the world＇s population is potentially affected by iron deficiency induced anemia, a leading cause of maternal death in African and Asian countries where people rely mostly on plants for their daily intake of iron. Iron can also be a limiting factor in the growth of economically important crop plants because of inadequate soil chemistry, and such deficiencies cannot easily be corrected by amending the soil. Improving the plant＇s ability to absorb iron in adverse conditions and to increase their overall content could offer solutions to these dramatic problems. Therefore understanding the molecular mechanisms regulating iron uptake and homeostasis in plants has potentially important practical applications both in agriculture and human health [3].     

What happens when tendons bend and twist? Proteoglycans

When tendons must bend or twist in order to fulfil their function of attaching muscle to bone they are subjected to forces that could damage the tendon. However, there are concomitant protective changes in the structure of the tendon at the location of bending. One of these changes involves increased synthesis and accumulation of the large proteoglycan aggrecan. The accumulation of aggrecan can protect the tendon by providing compressive stiffness, by allowing collagen fascicles to slide relative to one another, and by protecting vascular elements.     

The fossil tabanids (Diptera Tabanidae): when they began to appreciate warm blood and when they began transmit diseases?

A discussion of the known fossil tabanids (Diptera Tabanidae) is presented based on fossil evidence. This includes the origin of the hemathophagy in the Brachycera, more specifically for tabanids. Several tabanid species in the extant fauna are vectors for disease-producing organisms that affect humans and animals. Bacteria, viruses, rickettsiae, protozoa, and filarial worms can be transmitted by them, causing such diseases as anthrax, tularemia, anaplasmosis, various forms of trypanosomiasis, Q fever, and filariasis. However, if tabanids are directly responsible for all of these diseases is not consensual and the known fossil evidence is presented here.     

Know when to run,know when to hide: can behavioral differences explain the divergent invasion success of two sympatric lizards?

Invasive species represent a select subset of organisms that have successfully transitioned through each stage of the introduction process (transportation, establishment, and spread). Although there is a growing realization that behavior plays a critical role in invasion success, few studies have focused on the initial stages of introduction. We examined whether differences in the grouping tendencies and exploratory behavior of two sympatric lizard species could contribute to their divergent invasion success. While the nondirected activity of the two species did not differ, the invasive delicate skink (Lampropholis delicata) was found to be more exploratory than the congeneric noninvasive garden skink (L. guichenoti), which enabled it to more effectively locate novel environments and basking site resources. The delicate skink also exhibited a greater tendency to hide, which may act to enhance its probability of ensnarement in freight and cargo and decrease its likelihood of detection during transit. The grouping tendencies of the two species did not differ. Together, our results suggest that while the two species have an equivalent "opportunity" for unintentional human-assisted transportation, several pre-existing behavioral traits may enhance the success of the delicate skink in negotiating the initial stages of the introduction process, and subsequent post-establishment spread.     

Improving enzyme properties: when are closer mutations better?

Study of mutations that improve enzyme properties reveals that in many, but not all, cases closer mutations are more effective than distant ones. For enantioselectivity, substrate selectivity and new catalytic activity (catalytic promiscuity) closer mutations improved enzymes more effectively than distant ones. However, both close and distant mutations can improve activity, thermal stability and also probably stability toward organic solvents. Typical random mutagenesis methods, such as error-prone PCR, create greater numbers of distant mutations than close mutations because enzymes contain more amino acids distant from the active site than close to the active site. This suggests that instead of mutating the entire enzyme, focusing mutations near the substrate-binding site might dramatically increase the success rate in many directed evolution experiments.