New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Freezing and low temperature photoinhibition tolerance in cultivated potato and potato hybrids

Four Solanum tuberosum L. cultivars (Nicola, Pito, Puikula, Timo) and somatic hybrids between freezing tolerant S. commersonii and freezing sensitive S. tuberosum were evaluated for their tolerance to freezing and low temperature photoinhibition. Cellular freezing tolerance was studied using ion leakage tests and the sensitivity of the photosynthetic apparatus to freezing and high light intensity stress by measuring changes in chlorophyll fluorescence (FV/FM) and oxygen evolution. Exposure to high light intensities after freezing stress increased frost injury significantly in all genotypes studied. Compared with S. tuberosum cultivars, the hybrids were more tolerant both of freezing and intense light stresses. In field experiments the mechanism of frost injury varied according to the severity of night frosts. During night frosts in 1999, the temperature inside the potato canopy was significantly higher than at ground level, and did not fall below the lethal temperature for potato cultivars (from -2.5 to -3.0°C). As a result, frost injury developed slowly, indicating that damage occurred to the photosynthetic apparatus. However, as the temperature at ground level and inside the canopy fell below -4°C, cellular freezing occurred and the canopy was rapidly destroyed. This suggests that in the field visual frost damage can follow from freezing or non-freezing temperatures accompanied with high light intensity. Therefore, in an attempt to improve low temperature tolerance in potato, it is important to increase tolerance to both freezing and chilling stresses.Tutkimuksessa vertailtiin toisiinsa neljän perunalajikkeen (Solanum tuberosum L.) (Nicola, Pito, Puikula, Timo) ja kolmen somaattisen hybridin (S. commersonii x S. tuberosum) jäätymisen ja fotoinhibition kestävyyttä. Jäätymisen kestävyyttä mitattiin ionivuototestien avulla, ja yhteyttämiskoneiston herkkyyttä alhaisille lämpötiloille ja korkealle valolle tutkittiin seuraamalla klorofyllifluoresenssissa ja hapentuotannossa tapahtuvia muutoksia.Korkea valon intensiteetti heti jäätymisen jälkeen lisäsi hallavaurioita kaikilla tutkituilla perunagenotyypeillä. Kaikki perunahybridit kestivät paremmin jäätymistä ja korkeaa valoa kuin S. tuberosum lajikkeet. Peltokokeissa hallavauriomekanismit vaihtelivat vuosittain hallan ankaruuden mukaan. Syksyn 1999 yöhallojen yhteydessä lämpötila perunakasvuston sisällä oli huomattavasti korkeampi kuin maanpinnalta mitattu lämpötila. Itse asiassa kasvuston lämpötila ei koskaan laskenut alle perunan kuolettavan lämpötilan, joka vaihteli lajikkeen mukaan -2.5°C:sta -3.0°C:een. Tämän seurauksena hallavauriot levisivät kasvustossa hitaasti, mikä viittaa yhteyttämiskoneissa tapahtuneisiin vaurioihin sekä sen seurauksena tapahtuneeseen hapen radikaalien kertymiseen. Mikäli yölämpötila laski maanpinnalla ja kasvuston sisällä -4°C:een, kasvusto tuhoutui nopeasti. Tämän mukaan korkea valon intensiteetti ja alhainen lämpötila (jäätyminen tai vilutus) voivat yhdessä aiheuttaa hallavaurioita. Kun pyritään parantamaan perunan kylmänkestävyyttä, on tärkeää kiinnittää huomiota molempiin stresseihin, ja ottaa huomioon etenkin korkean valon aikaansaama hallavaurioiden lisääntyminen

Freezing and low temperature photoinhibition tolerance in cultivated potato and potato hybrids

Four Solanum tuberosum L. cultivars (Nicola, Pito, Puikula, Timo) and somatic hybrids between freezing tolerant S. commersonii and freezing sensitive S. tuberosum were evaluated for their tolerance to freezing and low temperature photoinhibition. Cellular freezing tolerance was studied using ion leakage tests and the sensitivity of the photosynthetic apparatus to freezing and high light intensity stress by measuring changes in chlorophyll fluorescence (FV/FM) and oxygen evolution. Exposure to high light intensities after freezing stress increased frost injury significantly in all genotypes studied. Compared with S. tuberosum cultivars, the hybrids were more tolerant both of freezing and intense light stresses. In field experiments the mechanism of frost injury varied according to the severity of night frosts. During night frosts in 1999, the temperature inside the potato canopy was significantly higher than at ground level, and did not fall below the lethal temperature for potato cultivars (from -2.5 to -3.0°C). As a result, frost injury developed slowly, indicating that damage occurred to the photosynthetic apparatus. However, as the temperature at ground level and inside the canopy fell below -4°C, cellular freezing occurred and the canopy was rapidly destroyed. This suggests that in the field visual frost damage can follow from freezing or non-freezing temperatures accompanied with high light intensity. Therefore, in an attempt to improve low temperature tolerance in potato, it is important to increase tolerance to both freezing and chilling stresses

Expression of glutathione-S-transferase and its role in plant growth and development in vivo and shoot morphogenesis in vitro

10.1007/s11103-004-4516-1Plant Molecular Biology57153-66PMBI

Interaction of climate change with effects of conspecific and heterospecific density on reproduction

We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density-dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms

Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design

* Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. * We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F. albicollis from 365 populations and 79 610 clutches. * Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. * These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition. [KEYWORDS: geographic location habitat latitude longitude nest box floor area nest box material

Clutch-size variation in Western Palaearctic secondary hole-nesting passerine birds in relation to nest box design

* Secondary hole-nesting birds that do not construct nest holes themselves and hence regularly breed in nest boxes constitute important model systems for field studies in many biological disciplines with hundreds of scientists and amateurs involved. Those research groups are spread over wide geographic areas that experience considerable variation in environmental conditions, and researchers provide nest boxes of varying designs that may inadvertently introduce spatial and temporal variation in reproductive parameters. * We quantified the relationship between mean clutch size and nest box size and material after controlling for a range of environmental variables in four of the most widely used model species in the Western Palaearctic: great tit Parus major, blue tit Cyanistes caeruleus, pied flycatcher Ficedula hypoleuca and collared flycatcher F. albicollis from 365 populations and 79 610 clutches. * Nest floor area and nest box material varied non-randomly across latitudes and longitudes, showing that scientists did not adopt a random box design. Clutch size increased with nest floor area in great tits, but not in blue tits and flycatchers. Clutch size of blue tits was larger in wooden than in concrete nest boxes. * These findings demonstrate that the size of nest boxes and material used to construct nest boxes can differentially affect clutch size in different species. The findings also suggest that the nest box design may affect not only focal species, but also indirectly other species through the effects of nest box design on productivity and therefore potentially population density and hence interspecific competition. [KEYWORDS: geographic location habitat latitude longitude nest box floor area nest box material]

Variation in clutch size in relation to nest size in birds.

Peer reviewe

The Complexity of Trust in Business Collaborations

Research on trust in business collaborations is generally founded on the premises that: a) cognitive trust is initially defined within contractual procedures; b) positive experiences lead to adjustments in contractual and/or informal arrangements, and c) cognitive trust is eventually supplanted by affective trust. This dynamic, process view of trust fails to capture the impact of trust experiences in external collaborations on trust emergence in a focal collaboration, and the complexity of trust co-evolution as each actor interprets and responds to the other's communication, behaviour and action. A complexity conceptualisation of trust as a self-organising, adaptive phenomenon can help us better understand the way trust develops. Through engaging with complexity theories as metaphors to enrich trust theory, trust is described as 'self-organising' as new cognitive, interpretive schema are evoked, and 'adapting' in response to trust experiences external to the collaboration. A complexity perspective evokes a new field of research questions and rich methodological opportunities