Is Consent Based on Trust Morally Inferior to Consent Based on Information?

Informed consent is considered by many to be a moral imperative in medical research. However, it is increasingly acknowledged that in many actual instances of consent to participation in medical research, participants do not employ the provided information in their decision to consent, but rather consent based on the trust they hold in the researcher or research enterprise. In this article we explore whether trust‐based consent is morally inferior to information‐based consent. We analyse the moral values essential to valid consent – autonomy, voluntariness, non‐manipulation, and non‐exploitation – and assess whether these values are less protected and promoted by consent based on trust than they are by consent based on information. We find that this is not the case, and thus conclude that trust‐based consent if not morally inferior to information‐based consent.     

Does Seed‐Caching Experience Affect Spatial Memory Performance by Pinyon Jays?

Food‐storing birds use spatial memory to find previously cached food items. Throughout winter, pinyon jays (Gymnorhinus cyanocephalus) rely heavily on cached pinyon pine (Pinus edulis) seeds. Because of a recent severe drought, pinyon pine trees had not produced a significant seed crop for several years. Therefore, 1‐ and 2‐yr‐old birds never had the opportunity to cache and recover seeds and birds 4 or more years of age had not recovered seeds in 3 yr. This study examined whether natural but extreme variability in experience might result in differences in abstract spatial memory ability during a non‐cache recovery test of spatial memory. Three groups of jays were tested for spatial memory ability in an open room analog of the radial arm maze. Two of the groups were 8 mo old: young/minimally experienced birds which had 2 mo of experience in the wild, while young/experienced birds had 5 mo of experience in their natural habitat. The third group, adult, consisted of birds more than 3 yr old, with at least 3 yr of experience in their natural habitat. This was the only group with experience caching pine seeds. All three groups performed equally and well above chance. This suggests that spatial memory is fully developed by 8 mo of age and is not affected by extensive experience in the wild.     

Is the Outgrowth of Transplant-Derived Axons Guided by Host Astrocytes and Myelin Loss?

Loss of cortical neurons may lead to sever and sometimes irreversible deficits in motor function in a number of neuropathological conditions. Absence of spontaneous axonal regeneration following trauma in the adult central nervous system (CNS) is attributed to inhibitory factors associated to the CNS white matter and to the non-permissive environment provided by reactive astrocytes that form a physical and biochemical barrier scar. Neural transplantation of embryonic neurons has been widely assessed as a potential approach to overcome the generally limited capacity of the mature CNS to regenerate axons or to generate new neurons in response to cell loss. We have recently shown that embryonic (E14) mouse motor cortical tissue transplanted into the damaged motor cortex of adult mice developed efferent projections to appropriate cortical and subcortical host targets including distant areas such as the spinal cord, with a topographical organization similar to that of intact motor cortex. Several parameters might account for the outgrowth of axonal projections from embryonic neurons within a presumably non-permissive adult brain, among which are astroglial reactions and myelin formation. In the present study, we have examined the role of astrocytes and myelin in the axonal outgrowth of transplanted neurons.Key Words: motor cortex, neuronal transplantation, embryonic cells, GFP, GFAP, PLP     

Is the Outgrowth of Transplant-Derived Axons Guided by Host Astrocytes and Myelin Loss?

Loss of cortical neurons may lead to sever and sometimes irreversible deficits in motor function in a number of neuropathological conditions. Absence of spontaneous axonal regeneration following trauma in the adult central nervous system (CNS) is attributed to inhibitory factors associated to the CNS white matter and to the non-permissive environment provided by reactive astrocytes that form a physical and biochemical barrier scar. Neural transplantation of embryonic neurons has been widely assessed as a potential approach to overcome the generally limited capacity of the mature CNS to regenerate axons or to generate new neurons in response to cell loss. We have recently shown that embryonic (E14) mouse motor cortical tissue transplanted into the damaged motor cortex of adult mice developed efferent projections to appropriate cortical and subcortical host targets including distant areas such as the spinal cord, with a topographical organization similar to that of intact motor cortex. Several parameters might account for the outgrowth of axonal projections from embryonic neurons within a presumably non-permissive adult brain, among which are astroglial reactions and myelin formation. In the present study, we have examined the role of astrocytes and myelin in the axonal outgrowth of transplanted neurons.     

Cognitive Performance of G?ttingen Minipigs Is Affected by Diet in a Spatial Hole-Board Discrimination Test

Consumption of a high energy diet, containing high amounts of saturated fat and refined sugar has been associated with impairment of cognitive function in rodents and humans. We sought to contrast the effect of a high fat/cholesterol, low carbohydrate diet and a low fat, high carbohydrate/sucrose diet, relative to a standard low fat, high carbohydrate minipig diet on spatial cognition with regards to working memory and reference memory in 24 male Göttingen minipigs performing in a spatial hole-board discrimination test. We found that both working memory and reference memory were impaired by both diets relative to a standard minipig diet high in carbohydrate, low in fat and sugar. The different diets did not impact levels of brain-derived neurotrophic factor in brain tissue and neither did they affect circulatory inflammation measured by concentrations of C-reactive protein and haptoglobin in serum. However, higher levels of triglycerides were observed for minipigs fed the diets with high fat/cholesterol, low carbohydrate and low fat, high carbohydrate/sucrose compared to minipigs fed a standard minipig diet. This might explain the observed impairments in spatial cognition. These findings suggest that high dietary intake of both fat and sugar may impair spatial cognition which could be relevant for mental functioning in humans.     

Perennial grassland dynamics on fertile plains: Is coexistence mediated by disturbance?

Abstract The response of grasslands to disturbance varies with the nature of the disturbance and the productivity of the landscape. In highly productive grasslands, competitive exclusion often results in decreased species richness and grazing may allow more species to coexist. Once widespread, grasslands dominated by Dichanthium sericeum (Queensland bluegrass) and Astrebla spp. (Mitchell grass) occur on fertile plains but have been reduced in extent by cultivation. We tested the effects of exclusion of livestock grazing on these grasslands by comparing the floristic composition of sites in a nature reserve with an adjacent stock reserve. In addition, sites that had been cultivated within the nature reserve were compared with those where grazing but no cultivation had occurred. To partition the effects of temporal variation from spatial variation we sampled sites in three different years (1998, 2002 and 2004). Some 194 taxa were recorded at the nature reserve and surrounding stock routes. Sampling time, the occurrence of past cultivation and livestock grazing all influenced species composition. Species richness varied greatly between sampling periods relating to highly variable rainfall and water availability on heavy clay soils. Native species richness was significantly lower at previously cultivated sites (13–22 years after cultivation), but was not significantly influenced by grazing exclusion. After 8 years it appears that reintroducing disturbance in the form of livestock grazing is not necessary to maintain plant species richness in the reserve. The highly variable climate (e.g. droughts) probably plays an important role in the coexistence of species by negating competitive exclusion and allowing interstitial species to persist.     

Daytime Depression in Tree Stem CO2 Efflux Rates: Is it Caused by Low Stem Turgor Pressure?

BACKGROUND AND AIMS: Daytime CO2 efflux rates (FCO2) from tree stems are often reported to be lower than expected from the exponential relationship between temperature and respiration. Explanations of daytime depression in FCO2 have focused on the possible role of internal CO2 transport in the xylem. However, another possible cause that has been overlooked is the daily dynamics of the water status in the living stem tissues and its influence on stem growth rate and thus respiration. The objective of this study was to assess the daily dynamics of stem water status and growth rate and to determine the extent to which they may be linked to daily variations in stem FCO2. METHODS: FCO2 of young beech and oak stems were measured under controlled conditions. Relative stem turgor pressure (Psi(p)), obtained from simulations with the 'RCGro' model, was used as an indicator of the water status in the living stem tissues. Daily dynamics of stem growth were derived from Psi(p): growth was assumed to occur when Psi(p) exceeded a relative threshold value. KEY RESULTS: There was a strong correspondence between fluctuations in FCO2 and simulated Psi(p). The non-growth conditions during daytime coincided with depressions in FCO2. Moreover, FCO2 responded to changes in Psi(p) in the absence of growth, indicating also that maintenance processes were influenced by the water status in the living stem tissues. CONCLUSIONS: Daytime depressions in stem FCO2 correlate with the daily dynamics of turgor, as a measure of the water status in the living stem tissues: it is suggested that water status of tree stems is a potentially important determinant of stem FCO2, as it influences the rate of growth and maintenance processes in the living tissues of the stem.     

The Origin of Eukaryotes Is Suggested as the Symbiosis of Pyrococcus into γ-Proteobacteria by Phylogenetic Tree Based on Gene Content

Attempts were made to define the relationship among the three domains (eukaryotes, archaea, and eubacteria) using phylogenetic tree analyses of 16S rRNA sequences as well as of other protein sequences. Since the results are inconsistent, it is implied that the eukaryotic genome has a chimeric structure. In our previous studies, the origin of eukaryotes to be the symbiosis of archaea into eubacteria using the whole open reading frames (ORF) of many genomes was suggested. In these studies, the species participating in the symbiosis were not clarified, and the effect of gene duplication after speciation (in-paralog) was not addressed. To avoid the influence of the in-paralog, we developed a new method to calculate orthologous ORFs. Furthermore, we separated eukaryotic in-paralogs into three groups by sequence similarity to archaea, eubacteria (other than -proteobacteria), and -proteobacteria and treated them as individual organisms. The relationship between the three ORF groups and the functional classification was clarified by this analysis. The introduction of this new method into the phylogenetic tree analysis of 66 organisms (4 eukaryotes, 13 archaea, and 49 eubacteria) based on gene content suggests the symbiosis of pyrococcus into -proteobacteria as the origin of eukaryotes.     

Is economy of competitive cyclists affected by the anterior–posterior foot position on the pedal?

The primary purpose of this investigation was to test the hypothesis that cycling economy, as measured by rate of oxygen consumption (VO(2)) in healthy, young, competitive cyclists pedaling at a constant workrate, increases (i.e. VO(2) decreases) when the attachment point of the foot to the pedal is moved posteriorly on the foot. The VO(2) of 11 competitive cyclists (age 26.8+/-8.9 years) was evaluated on three separate days with three anterior-posterior attachment points of the foot to the pedal (forward=traditional; rear=cleat halfway between the head of the first metatarsal and the posterior end of the calcaneous; and mid=halfway between the rear and forward positions) on each day. With a randomly selected foot position, VO(2) was measured as each cyclist pedaled at steady state with a cadence of 90 rpm and with a power output corresponding to approximately 90% of their ventilatory threshold (VT) (mean power output 203.3+/-20.8 W). After heart rate returned to baseline, VO(2) was measured again as the subject pedaled with a different anterior-posterior foot position, followed by another rest period and then VO(2) was measured at the final foot position. The key finding of this investigation was that VO(2) was not affected by the anterior-posterior foot position either for the group (p=0.311) or for any individual subject (p>or=0.156). The VO(2) for the group was 2705+/-324, 2696+/-337, and 2747+/-297 ml/min for the forward, mid, and rear foot positions, respectively. The practical implication of these findings is that adjusting the anterior-posterior foot position on the pedal does not affect cycling economy in competitive cyclists pedaling at a steady-state power output eliciting approximately 90% of VT.     

Is selection of host plants by Plagiodera versicolora based on plant‐related performance?

Plant-related performance may be one of the most important factors in the selection of host plants by insect herbivores. We investigated the importance of plant-related performance in host selection by the willow leaf beetle, Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae), on four willow species: Salix chaenomeloides Kimura, Salix eriocarpa Fr. et Sav., Salix   integra Thunb., and Salix serissaefolia Kimura (Salicaceae). Bagging experiments in the field revealed that the performance of P. versicolora adults and larvae differed significantly among willow species under enemy-free conditions and at constant densities. Egg clutch and larval abundance were positively related to adult abundance. Plagiodera versicolora adults did not discriminate strongly among willow species for feeding and oviposition. Larval performance did not differ among willow species in the presence of natural enemies, suggesting that interspecific differences in host quality were overridden by mortality from natural enemies. Adult and egg clutch abundance of P. versicolora changed seasonally despite the temporal stability of adult and larval performance under enemy-free field conditions. Thus, plant-related performance of P. versicolora adults and larvae may contribute little to population growth and temporal dynamics of host use in P. versicolora . Potential factors that reduce discrimination of P. versicolora among host willow species are discussed.     

Is Order the Defining Feature of Magnitude Representation? An ERP Study on Learning Numerical Magnitude and Spatial Order of Artificial Symbols

Using an artificial-number learning paradigm and the ERP technique, the present study investigated neural mechanisms involved in the learning of magnitude and spatial order. 54 college students were divided into 2 groups matched in age, gender, and school major. One group was asked to learn the associations between magnitude (dot patterns) and the meaningless Gibson symbols, and the other group learned the associations between spatial order (horizontal positions on the screen) and the same set of symbols. Results revealed differentiated neural mechanisms underlying the learning processes of symbolic magnitude and spatial order. Compared to magnitude learning, spatial-order learning showed a later and reversed distance effect. Furthermore, an analysis of the order-priming effect showed that order was not inherent to the learning of magnitude. Results of this study showed a dissociation between magnitude and order, which supports the numerosity code hypothesis of mental representations of magnitude.     

Is zonation on coastal sand dunes determined primarily by sand burial or by salt spray? A test in New Zealand dunes

There has long been controversy on which environmental factor is the predominant determinant of community zonation on sand dunes. It is demonstrated here that, on a dune system in southern New Zealand, several environmental factors that could limit growth all vary along the sea-to-inland sand dune zonation: soil moisture, soil nutrients, wind exposure, sand burial, salt spray and soil salinity. Correlation of the responses of 30 species to experimental stress (burial, darkness, rooting-medium salinity and salt spray) with the zonation of the species in the field indicates that, in the four dune systems studied, sand burial and salt are both important, with salt generally being the more important. However, the relative importance of the factors differs between sites.     

Is It Possible to Improve Memory Function by Upregulation of the Cholesterol 24S-Hydroxylase (CYP46A1) in the Brain?

We previously described a heterozygous mouse model overexpressing human HA-tagged 24S-hydroxylase (CYP46A1) utilizing a ubiquitous expression vector. In this study, we generated homozygotes of these mice with circulating levels of 24OH 30–60% higher than the heterozygotes. Female homozygous CYP46A1 transgenic mice, aged 15 months, showed an improvement in spatial memory in the Morris water maze test as compared to the wild type mice. The levels of N-Methyl-D-Aspartate receptor 1, phosphorylated-N-Methyl-D-Aspartate receptor 2A, postsynaptic density 95, synapsin-1 and synapthophysin were significantly increased in the hippocampus of the CYP46A1 transgenic mice as compared to the controls. The levels of lanosterol in the brain of the CYP46A1 transgenic mice were significantly increased, consistent with a higher synthesis of cholesterol. Our results are discussed in relation to the hypothesis that the flux in the mevalonate pathway in the brain is of importance in cognitive functions.     

Is the titer of adipokinetic peptides in Leptinotarsa decemlineata fed on genetically modified potatoes increased by oxidative stress?

The level of adipokinetic hormones (AKHs) (Peram-CAH-I and II) in the corpora cardiaca and the hemolymph of Leptinotarsa decemlineata enormously increases in the adults fed on genetically modified potatoes containing either GNA lectin or Cry 3Aa toxin concomitant with increased oxidative stress in gut tissues. A similar enhancement of the AKH titer is achieved when the adults are injected with paraquat that evokes oxidative stress. On the other hand, an injection of exogenous AKH reduces oxidative stress biomarkers in the hemolymph by reducing protein carbonyls and enhancing reduced glutathione levels. These facts indicate that there is a feedback regulation between an oxidative stressor action and the level of AKH in the insect body, and that AKHs might be involved in the activation of an antioxidant protection mechanism. These results are to our knowledge, the first evidence for the involvement of AKHs in oxidative stress mitigation, in addition to a plethora of other roles.     

Effect of Day and Night Temperature on Internode and Stem Length in Chrysanthemum: Is Everything Explained by DIF?

In many plant species, including chrysanthemum, a strong positive correlation between internode length and DIF [difference between day (DT) and night (NT) temperature] has been observed. However, Langton and Cockshull (1997. Scientia Horticulturae 69: 229-237) reported no such relationship and showed that absolute DT and NT explained internode length rather than DIF. To investigate these conflicting results and to clarify the validity of the DIF concept, cut chrysanthemums (Chrysanthemum 'Reagan Improved') were grown in growth chambers at all 16 combinations of four DT and four NT (16, 20, 24 and 28 degrees C) with a 12 h day length. Length of internode 10, number of internodes and stem length were measured on days 5, 10, 17, 22 and 27 after starting the temperature treatments. Internode length on day 10 showed a positive linear relationship with DIF (R2 = 0.64). However, when internodes had reached their final length in all treatments (day 27), a much stronger positive linear relation was observed (R2 = 0.81). A model to predict final internode length was developed based on the absolute DT and NT responses: both responses were optimum curves and no significant interaction between DT and NT occurred [final internode length (mm) = -32.23 + 3.56DT + 1.08NT - 0.0687DT2 - 0.0371NT2; R2 = 0.91, where TD is day temperature and TN is night temperature]. It is shown that DIF can predict final internode length only within a temperature range where effects of DT and NT are equal in magnitude and opposite in sign (18-24 degrees C). Internode appearance rate, as well as stem length formed during the experiment, showed an optimum response to DT.