Are larks future-oriented and owls present-oriented? Age- and sex-related shifts in chronotype–time perspective associations

The chronotype (morningness/eveningness) relates to individual differences in circadian preferences. Time perspective (past, present, future) refers to the preference to rely on a particular temporal frame for decision-making processes and behavior. First evidence suggests that future time perspective is associated with greater morningness and present time perspective with greater eveningness. However, little is known about how chronotype–time perspective relationships may alter over the life span. This present study investigated links between chronotype and time perspective more thoroughly by taking age and sex into account as well. Seven hundred six participants aged between 17 and 74 completed German adaptations of the Morningness--Eveningness Questionnaire (MEQ) and Zimbardo Time Perspective Inventory (ZTPI). Controlling for age and sex, relationships between morningness and future time perspective as well as between eveningness and present time perspective were replicated. These findings were supported by significant associations between time perspective and midpoint of sleep. Future time perspective was linked to earlier midpoints of sleep, indicating an early chronotype. Present time perspective was associated with later midpoints of sleep, indicating a late chronotype. However, age and sex had an impact on the chronotype–time perspective relationships. In all age groups, male larks were more future-oriented and less present-oriented, male owls more present-oriented and less future-oriented. The same conclusion could be drawn for female adolescents and young adults. For female adults above 30, there was no interrelationship between morningness and future time perspective but between eveningness and past time perspective. Female adult owls were more present-oriented as well as more past-oriented. Female adult larks were less present-oriented and less past-oriented. Findings are discussed in the light of neuroendocrine and serotonergic functioning.     

Explaining Dioscorides' "double difference": why are some mushrooms poisonous, and do they signal their unprofitability?

The adaptive significance of toxins in mushrooms has received very little consideration, although it is clear that poisons have appeared (and/or disappeared) many times in mushrooms' evolutionary history. One possibility is that poisons have evolved in some mushroom species to deter their consumption by would-be fungivores before spore dispersal. If this is so, then one might expect poisonous mushrooms to signal their unprofitability in some way. In this study, we have conducted the first formal analysis of the ecological and morphological traits associated with edible and poisonous mushrooms in North America and Europe. Poisonous mushrooms do not tend to be more colorful or aggregated than edible mushrooms, but they are more likely to exhibit distinctive odors even when phylogenetic relationships are accounted for. This raises the intriguing possibility that some poisonous species of mushrooms have evolved warning odors (and perhaps tastes) to enhance avoidance learning by fungivores.     

Thermozymes: biotechnology and structure–function relationships

Recent findings on the biochemical and molecular features of the following thermozymes are presented, based on their biotechnological use: α-amylase and amylopullulanase, used in starch processing; glucose isomerase, used in sweetener production; alcohol dehydrogenase, used in chemical synthesis; and alkaline phosphatase, used in diagnostics. The corresponding genes and recombinant proteins have been characterized in terms of sequence similarities, specific activities, thermophilicity, and unfolding kinetics. Site-directed and nested deletion mutagenesis were used to understand structure–function relationships. All these thermozymes display higher stability and activity than their counterparts currently used in the biotechnology industry. Received: January 22, 1998 / Accepted: February 16, 1998     

Reconstituting the kinetochore–microtubule interface: what, why, and how

The kinetochore is the proteinaceous complex that governs the movement of duplicated chromosomes by interacting with spindle microtubules during mitosis and meiosis. Faithful chromosome segregation requires that kinetochores form robust load-bearing attachments to the tips of dynamic spindle microtubules, correct microtubule attachment errors, and delay the onset of anaphase until all chromosomes have made proper attachments. To understand how this macromolecular machine operates to segregate duplicated chromosomes with exquisite accuracy, it is critical to reconstitute and study kinetochore–microtubule interactions in vitro using defined components. Here, we review the current status of reconstitution as well as recent progress in understanding the microtubule-binding functions of kinetochores in vivo.     

Detecting biodiversity hotspots using species–area and endemics–area relationships: the case of butterflies

Using data of the Red Data Book of European Butterflies we establish the species–area relationship (S = 8.5 A^0.23) and the endemics–area relationship (S = 0.5 A^0.18) of European butterflies. Applying confidence limits as tools for the identification of hotspot countries we show that in the case of butterflies hotspots of endemism and hotspots of overall species richness do not coincide. We introduce plots of residuals from species–area relationships shifted upwards by the 95% confidence limits of the intercept (α-values) as a new tool for identifying and ranking of hotspots.     

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.     

Motualevic acids and analogs: Synthesis and antimicrobial structure–activity relationships

Synthesis of the marine natural products motualevic acids A, E, and analogs in which modifications have been made to the ω-brominated lipid (E)-14,14-dibromotetra-deca-2,13-dienoic acid or amino acid unit are reported, together with antimicrobial activities against Staphylococcus aureus, methicillin-resistant S. aureus, Enterococcus faecium, and vancomycin-resistant Enterococcus.     

Single nucleotide polymorphism libraries: why and how are we building them?

A great deal of time and money is currently being invested in the production of large libraries of single nucleotide polymorphisms (SNPs) - variations of one nucleotide between the DNA sequence of individuals. This review compares and contrasts the available sources of SNP data, and describes the rationale behind the SNP mapping efforts, from the study of common diseases to unraveling an individual's response to medication.     

Odonates,gregarines and water mites: why are the same host species infected by both parasites?

1. Damselflies and dragonflies are widely parasitised insects and numerous studies have tried to understand this host–parasite relationship. However, most of these studies have concentrated on a single host species, neglecting the larger pattern within the Odonata order. 2. The aim of this paper was to examine different damselfly and dragonfly species for common endo‐ and ectoparasites and whether a general infection pattern can be found. Additionally, the goal was to investigate whether the phylogeny of the host species could explain these possible infection patterns. To this end, a dataset from the existing literature was compiled and the prevalence of endoparasitic gregarines and ectoparasitic water mites was analysed for 46 different odonate species. 3. Three distinct patterns were found: (i) most of the odonate host species had both gregarines and water mites, rather than only either one or neither; (ii) there appears to be a positive association between gregarine and water mite prevalences across host species; (iii) a weak phylogenetic signal was detected in gregarine prevalence and a strong one in water mite prevalence. 4. It is hypothesised that, due to the infection and transmission mechanisms by which water mites and gregarines infect different odonate host species, parasitism is aggregated to common, high‐density species. However, much research is needed in order to fully understand this relationship between odonates and their parasites, especially within the same host populations and host species assemblages.     

A structural and functional perspective on the evolution of the heme–copper oxidases

The heme–copper oxidases (HCOs) catalyze the reduction of O₂ to water, and couple the free energy to proton pumping across the membrane. HCOs are divided into three sub-classes, A, B and C, whose order of emergence in evolution has been controversial. Here we have analyzed recent structural and functional data on HCOs and their homologues, the nitric oxide reductases (NORs). We suggest that the C-type oxidases are ancient enzymes that emerged from the NORs. In contrast, the A-type oxidases are the most advanced from both structural and functional viewpoints, which we interpret as evidence for having evolved later.