Hydroclimatic changes on multiple timescales since 7800 y BP in the winter precipitation-dominated Central Asia.

Central Asia (CA) is one of the world's most significant arid regions, which is markedly impacted by global warming. A better understanding of the dynamical processes governing its Holocene climate variability is critical for a better understanding of possible future impacts of climate change in the region. To date, most of the existing CA paleoclimate records are from the summer precipitation-dominated eastern CA (ECA), with few records from the winter precipitation-dominated western CA (WCA). Here, we present a precisely dated (~6‰) and highly resolved (<4-y) record of hydroclimatic variations from the WCA covering the period between 7,774 and 656 y BP. Utilizing multiple proxies (δ18O, δ13C, and Sr/Ca) derived from a stalagmite from the Fergana Valley, Kyrgyzstan, we reveal a long-term drying trend in WCA, which is in contrast with the wetting trend in ECA. We propose that different responses of winter and summer westerly jets to seasonal solar insolation over the past 8,000 y may have resulted in an antiphased precipitation relationship between the WCA and ECA. Our data contain dominant quasiperiodicities of 1,400, 50 to 70, and 20 to 30 y, indicating close connections between the WCA climate and the North Atlantic. We further identified a series of droughts and pluvials on centennial-to-decadal timescales, which may have influenced regional societies and trans-Eurasian culture exchanges during historical and prehistorical times.

Loss of flockmates weakens winter site fidelity in golden-crowned sparrows (Zonotrichia atricapilla).

Animal social interactions have an intrinsic spatial basis as many of these interactions occur in spatial proximity. This presents a dilemma when determining causality: Do individuals interact socially because they happen to share space, or do they share space because they are socially linked? We present a method that uses demographic turnover events as a natural experiment to investigate the links between social associations and space use in the context of interannual winter site fidelity in a migratory bird. We previously found that golden-crowned sparrows (Zonotrichia atricapilla) show consistent flocking relationships across years, and that familiarity between individuals influences the dynamics of social competition over resources. Using long-term data on winter social and spatial behavior across 10 y, we show that i) sparrows exhibit interannual fidelity to winter home ranges on the scale of tens of meters and ii) the precision of interannual site fidelity increases with the number of winters spent, but iii) this fidelity is weakened when sparrows lose close flockmates from the previous year. Furthermore, the effect of flockmate loss on site fidelity was higher for birds that had returned in more than 2 winters, suggesting that social fidelity may play an increasingly important role on spatial behavior across the lifetime of this migratory bird. Our study provides evidence that social relationships can influence site fidelity, and shows the potential of long-term studies for disentangling the relationship between social and spatial behavior.

Chilling or chemical induction of dormancy release in blackcurrant (Ribes nigrum) buds is associated with characteristic shifts in metabolite profiles.

This study reveals striking differences in the content and composition of hydrophilic and lipophilic compounds in blackcurrant buds (Ribes nigrum L., cv. Ben Klibreck) resulting from winter chill or chemical dormancy release following treatment with ERGER, a biostimulant used to promote uniform bud break. Buds exposed to high winter chill exhibited widespread shifts in metabolite profiles relative to buds that experience winter chill by growth under plastic. Specifically, extensive chilling resulted in significant reductions in storage lipids and phospholipids, and increases in galactolipids relative to buds that experienced lower chill. Similarly, buds exposed to greater chill exhibited higher levels of many amino acids and dipeptides, and nucleotides and nucleotide phosphates than those exposed to lower chilling hours. Low chill buds (IN) subjected to ERGER treatment exhibited shifts in metabolite profiles similar to those resembling high chill buds that were evident as soon as 3 days after treatment. We hypothesise that chilling induces a metabolic shift which primes bud outgrowth by mobilising lipophilic energy reserves, enhancing phosphate availability by switching from membrane phospholipids to galactolipids and enhancing the availability of free amino acids for de novo protein synthesis by increasing protein turnover. Our results additionally suggest that ERGER acts at least in part by priming metabolism for bud outgrowth. Finally, the metabolic differences presented highlight the potential for developing biochemical markers for dormancy status providing an alternative to time-consuming forcing experiments.

Atmospheric forcing dominates winter Barents-Kara sea ice variability on interannual to decadal time scales.

The last two decades have seen a dramatic decline and strong year-to-year variability in Arctic winter sea ice, especially in the Barents-Kara Sea (BKS), changes that have been linked to extreme midlatitude weather and climate. It has been suggested that these changes in winter sea ice arise largely from a combined effect of oceanic and atmospheric processes, but the relative importance of these processes is not well established. Here, we explore the role of atmospheric circulation patterns on BKS winter sea ice variability and trends using observations and climate model simulations. We find that BKS winter sea ice variability is primarily driven by a strong anticyclonic anomaly over the region, which explains more than 50% of the interannual variability in BKS sea-ice concentration (SIC). Recent intensification of the anticyclonic anomaly has warmed and moistened the lower atmosphere in the BKS by poleward transport of moist-static energy and local processes, resulting in an increase in downwelling longwave radiation. Our results demonstrate that the observed BKS winter sea-ice variability is primarily driven by atmospheric, rather than oceanic, processes and suggest a persistent role of atmospheric forcing in future Arctic winter sea ice loss.

Variation in Thermal Sensitivity of Diapause Development among Individuals and over Time Predicts Life History Timing in a Univoltine Insect.

AbstractPhysiological time is important for understanding the development and seasonal timing of ectothermic animals but has largely been applied to developmental processes that occur during spring and summer, such as morphogenesis. There is a substantial knowledge gap in the relationship between temperature and development during winter, a season that is increasingly impacted by climate change. Most temperate insects overwinter in diapause, a developmental process with little obvious morphological change. We used principles from the physiological time literature to measure and model the thermal sensitivity of diapause development rate in the apple maggot fly Rhagoletis pomonella, a univoltine fly whose diapause duration varies substantially within and among populations. We show that diapause duration can be predicted by modeling a relationship between temperature and development rate that is shifted toward lower temperatures compared with typical models of morphogenic, nondiapause development. However, incorporating interindividual variation and ontogenetic variation in the temperature-to-development rate relationship was critical for accurately predicting fly emergence, as diapause development proceeded more quickly at high temperatures later in diapause. We conclude that the conceptual framework may be flexibly applied to other insects and discuss possible mechanisms of diapause timers and implications for phenology with warming winters.

Multiple cropping effectively increases soil bacterial diversity, community abundance and soil fertility of paddy fields.

BACKGROUND: Crop diversification is considered as an imperative approach for synchronizing the plant nutrient demands and soil nutrient availability. Taking two or more crops from the same field in one year is considered as multiple cropping. It improves the diversity and abundance of soil microbes, thereby improving the growth and yield of crops. Therefore, the present study was conducted to explore the effects of different multiple winter cropping on soil microbial communities in paddy fields. In this study, eight rice cropping patterns from two multiple cropping systems with three different winter crops, including Chinese milk vetch (CMV), rape, and wheat were selected. The effects of different multiple winter cropping on soil microbial abundance, community structure, and diversity in paddy fields were studied by 16 S rRNA high-throughput sequencing and real-time fluorescence quantitative polymerase chain reaction (PCR). RESULTS: The results showed that different multiple winter cropping increased the operational taxonomic units (OTUs), species richness, and community richness index of the bacterial community in 0 ~ 20 cm soil layer. Moreover, soil physical and chemical properties of different multiple cropping patterns also affected the diversity and abundance of microbial bacterial communities. The multiple cropping increased soil potassium and nitrogen content, which significantly affected the diversity and abundance of bacterial communities, and it also increased the overall paddy yield. Moreover, different winter cropping changed the population distribution of microorganisms, and Proteobacteria, Acidobacteria, Nitrospira, and Chloroflexi were identified as the most dominant groups. Multiple winter cropping, especially rape-early rice-late rice (TR) andChinese milk vetch- early rice-late rice (TC) enhanced the abundance of Proteobacteria, Acidobacteria, and Actinobacteria and decreased the relative abundance of Verrucomicrobia and Euryarchaeota. CONCLUSION: In conclusion, winter cropping of Chinese milk vetch and rape were beneficial to improve the soil fertility, bacteria diversity, abundance and rice yield.

Beyond floral initiation: the role of flower bud dormancy in flowering time control of annual plants.

The phenology of temperate perennials, including the timing of vegetative growth and flowering, is well known to be controlled by seasonal dormancy cycles. Dormant structures are known as buds and have specialised covering structures, symplastic isolation from the plant and often autonomous stores of carbon and nitrogen reserves. In contrast, in annual plants our current understanding of the control of the timing of flowering focuses on the mechanisms affecting floral initiation, the transition from a vegetative apical meristem to a inflorescence meristem producing flower primordia in place of leaves. Recently we revealed that annual crops in Brassicaceae exhibit chilling-responsive growth control in a manner closely resembling bud dormancy breakage in perennial species. Here I discuss evidence that vernalisation in autumn is widespread and discuss its role in inducing flower bud set prior to winter, and review evidence that flower bud dormancy has a more wide-spread role in annual plant flowering time control than previously appreciated.

Seasonal vitamin D levels and lupus low disease activity state in systemic lupus erythematosus.

BACKGROUND: Seasonal variation and sunlight exposure can impact serum vitamin D levels, potentially influencing lupus symptoms. We investigated seasonal vitamin D levels and their correlation with clinical manifestations and disease activity in systemic lupus erythematosus (SLE). METHODS: Serum 25(OH) vitamin D3 (25(OH)D3) levels were categorised as deficient (25(OH)D3 < 10 ng/mL), insufficient (10-30 ng/mL) and sufficiency (>30 ng/mL) in participants analysed in winter (n = 407) and summer (n = 377). Logistic regression analysis was performed to assess the impact of vitamin D levels on achieving a lupus low disease activity state (LLDAS), stratified by season. RESULTS: The mean serum 25(OH)D3 levels differed significantly between the winter and summer measurement groups (22.4 vs. 24.2 ng/mL; p = .018). The prevalences of vitamin D deficiency, insufficiency and sufficiency in the winter group were 12.8%, 66.6% and 20.6%, respectively, compared with 4.5%, 67.9% and 27.6% in the summer group. Achieving LLDAS was highest in the vitamin D sufficiency group (winter: 56.6%, summer: 55%) and lowest in the vitamin D deficiency group (winter: 15.4%, summer: 13.6%), with significant differences (all p < .001). Multivariate analysis identified SLE disease activity index ≤4, normal anti-double-stranded DNA and vitamin D sufficiency as significant factors for achieving LLDAS in both seasons. CONCLUSIONS: Sufficient vitamin D levels are important for achieving LLDAS in patients with SLE during winter and summer. Therefore, physicians should pay attention to the adequacy of vitamin D levels and consider recommending vitamin D supplementation for patients with vitamin D insufficiency.

Disentangling the drivers of urban bird diversity in the non-breeding season: A general synthesis.

Current knowledge about the impacts of urbanisation on bird assemblages is based on evidence from studies partly or wholly undertaken in the breeding season. In comparison, the non-breeding season remains little studied, despite the fact that winter conditions at higher latitudes are changing more rapidly than other seasons. During the non-breeding season, cities may attract or retain bird species because they offer milder conditions or better feeding opportunities than surrounding habitats. However, the range of climatic, ecological and anthropogenic mechanisms shaping different facets of urban bird diversity in the non-breeding season are poorly understood. We explored these mechanisms using structural equation modelling to assess how urbanisation affects the taxonomic, phylogenetic and functional diversity of avian assemblages sampled worldwide in the non-breeding season. We found that minimum temperature, elevation, urban area and city age played a critical role in determining taxonomic diversity while a range of factors-including productivity, precipitation, elevation, distance to coasts and rivers, socio-economic (as a proxy of human facilitation) and road density-each contributed to patterns of phylogenetic and functional diversity. The structure and function of urban bird assemblages appear to be predominantly shaped by temperature, productivity and city age, with effects of these factors differing across seasons. Our results underline the importance of considering multiple hypotheses, including seasonal effects, when evaluating the impacts of urbanisation on biodiversity.

Expansion of the prenatal phenotype of Baraitser-Winter syndrome: Presentation of two cases of multiple congenital anomaly syndrome.

Baraitser-Winter cerebrofrontofacial syndrome (BWCFF) is a variable multiple congenital anomaly condition, typically presenting postnatally with neurocognitive delays, distinctive facial features, cortical brain malformations, and in some, a variety of additional congenital malformations. However, only a few cases have reported the prenatal presentation of this syndrome. Here, we report two cases of BWCFF and their associated prenatal findings. One case presented with non-immune hydrops fetalis and a horseshoe kidney and was found to have a de novo heterozygous variant in ACTB (c.158A>G). The second case presented with gastroschisis, bilateral cleft lip and palate, and oligohydramnios, and was found to harbor a different de novo variant in ACTB (c.826G>A). Limited reports exist describing prenatally identified anomalies that include fetal growth restriction, increased nuchal fold, bilateral hydronephrosis, rocker bottom foot, talipes, cystic hygroma, omphalocele, and hydrops fetalis. In addition, only three of these cases have included detailed prenatal imaging findings. The two prenatal cases presented here demonstrate an expansion of the prenatal phenotype of BWCFF to include gastroschisis, lymphatic involvement, and oligohydramnios, which should each warrant consideration of this diagnosis in the setting of additional anomalies.

Neural thyroid hormone metabolism integrates seasonal changes in environmental temperature with the neuroendocrine reproductive axis.

We asked if environmental temperature alters thyroid hormone metabolism within the hypothalamus, thereby providing a neuroendocrine mechanism by which temperature could be integrated with photoperiod to regulate seasonal rhythms. We used immunohistochemistry to assess the effects of low-temperature winter dormancy at 4 °C or 12 °C on thyroid-stimulating hormone (TSH) within the infundibulum of the pituitary as well as deiodinase 2 (Dio2) and 3 (Dio3) within the hypothalamus of red-sided garter snakes (Thamnophis sirtalis). Both the duration and, in males, magnitude of low-temperature dormancy altered deiodinase immunoreactivity within the hypothalamus, increasing the area of Dio2-immunoreactivity in males and females and decreasing the number of Dio3-immunoreactive cells in males after 8-16 weeks. Reciprocal changes in Dio2/3 favor the accumulation of triiodothyronine within the hypothalamus. Whether TSH mediates these effects requires further study, as significant changes in TSH-immunoreactive cell number were not observed. Temporal changes in deiodinase immunoreactivity coincided with an increase in the proportion of males exhibiting courtship behavior as well as changes in the temporal pattern of courtship behavior after emergence. Our findings mirror those of previous studies, in which males require low-temperature exposure for at least 8 weeks before significant changes in gonadotropin-releasing hormone immunoreactivity and sex steroid hormones are observed. Collectively, these data provide evidence that the neuroendocrine pathway regulating the reproductive axis via thyroid hormone metabolism is capable of transducing temperature information. Because all vertebrates can potentially use temperature as a supplementary cue, these results are broadly applicable to understanding how environment-organism interactions mediate seasonally adaptive responses.

Ice in the intertidal: patterns and processes of freeze tolerance in intertidal invertebrates.

Many intertidal invertebrates are freeze tolerant, meaning that they can survive ice formation within their body cavity. Freeze tolerance is a fascinating trait, and understanding its mechanisms is important for predicting the survival of intertidal animals during extreme cold weather events. In this Review, we bring together current research on the ecology, biochemistry and physiology of this group of freeze-tolerant organisms. We first introduce the ecology of the intertidal zone, then highlight the strong geographic and taxonomic biases within the current body of literature on this topic. Next, we detail current knowledge on the mechanisms of freeze tolerance used by intertidal invertebrates. Although the mechanisms of freeze tolerance in terrestrial arthropods have been well-explored, marine invertebrate freeze tolerance is less well understood and does not appear to work similarly because of the osmotic differences that come with living in seawater. Freeze tolerance mechanisms thought to be utilized by intertidal invertebrates include: (1) low molecular weight cryoprotectants, such as compatible osmolytes and anaerobic by-products; (2) high molecular weight cryoprotectants, such as ice-binding proteins; as well as (3) other molecular mechanisms involving heat shock proteins and aquaporins. Lastly, we describe untested hypotheses, methods and approaches that researchers can use to fill current knowledge gaps. Understanding the mechanisms and consequences of freeze tolerance in the intertidal zone has many important ecological implications, but also provides an opportunity to broaden our understanding of the mechanisms of freeze tolerance more generally.

Thermal constraints on exercise and metabolic performance do not explain the use of dormancy as an overwintering strategy in the cunner (Tautogolabrus adspersus).

Winter cold slows ectotherm physiology, potentially constraining activities and ecological opportunities at poleward latitudes. Yet, many fishes are winter-active, facilitated by thermal compensation that improves cold performance. Conversely, winter-dormant fishes (e.g. cunner, Tautogolabrus adspersus) become inactive and non-feeding overwinter. Why are certain fishes winter-dormant? We hypothesized that winter dormancy is an adaptive behavioural response arising in poleward species that tolerate severe, uncompensated constraints of cold on their physiological performance. We predicted that below their dormancy threshold of 7--8°C, exercise and metabolic performance of cunner are greatly decreased, even after acclimation (i.e. shows above-normal, uncompensated thermal sensitivity, Q10>1-3). We measured multiple key performance metrics (e.g. C-start maximum velocity, chase swimming speed, aerobic scope) in cunner after acute exposure to 26-2°C (3°C intervals using 14°C-acclimated fish) or acclimation (5-8 weeks) to 14-2°C (3°C intervals bracketing the dormancy threshold). Performance declined with cooling, and the acute Q10 of all six performance rate metrics was significantly greater below the dormancy threshold temperature (Q10,acute8-2°C=1.5-4.9, mean=3.3) than above (Q10,acute14-8°C=1.1-1.9, mean=1.5), inferring a cold constraint. However, 2°C acclimation (temporally more relevant to seasonal cooling) improved performance, abolishing the acute constraint (Q10,acclimated8-2°C=1.4-3.0, mean=2.0; also cf. Q10,acclimated14-8°C=1.2-2.9, mean=1.7). Thus, dormant cunner show partial cold-compensation of exercise and metabolic performance, similar to winter-active species. However, responsiveness to C-start stimuli was greatly cold-constrained even following acclimation, suggesting dormancy involves sensory limitation. Thermal constraints on metabolic and exercise physiology are not significant drivers of winter dormancy in cunner. In fact, compensatory plasticity at frigid temperatures is retained even in a dormant fish.

Environmental variation associated with overwintering elicits marked metabolic plasticity in a temperate salmonid, Salvelinus fontinalis.

Poleward winters commonly expose animals, including fish, to frigid temperatures and low food availability. Fishes that remain active over winter must therefore balance trade-offs between conserving energy and maintaining physiological performance in the cold, yet the extent and underlying mechanisms of these trade-offs are not well understood. We investigated the metabolic plasticity of brook char (Salvelinus fontinalis), a temperate salmonid, from the biochemical to whole-animal level in response to cold and food deprivation. Acute cooling (1°C day-1) from 14°C to 2°C had no effect on food consumption but reduced activity by 77%. We then assessed metabolic performance and demand over 90 days with exposure to warm (8°C) or cold winter (2°C) temperatures while fish were fed or starved. Resting metabolic rate (RMR) decreased substantially during initial cooling from 8°C to 2°C (Q10=4.2-4.5) but brook char exhibited remarkable thermal compensation during acclimation (Q10=1.4-1.6). Conversely, RMR was substantially lower (40-48%) in starved fish, conserving energy. Thus, the absolute magnitude of thermal plasticity may be masked or modified under food restriction. This reduction in RMR was associated with atrophy and decreases in in vivo protein synthesis rates, primarily in non-essential tissues. Remarkably, food deprivation had no effect on maximum oxygen uptake rates and thus aerobic capacity, supporting the notion that metabolic capacity can be decoupled from RMR in certain contexts. Overall, our study highlights the multi-faceted energetic flexibility of Salvelinus spp. that likely contributes to their success in harsh and variable environments and may be emblematic of winter-active fishes more broadly.

High freezing sensitivity of legumes relative to other herbaceous species in northern temperate plant communities.

BACKGROUND AND AIMS: Reduced snow cover and increased air temperature variability are predicted to expose overwintering herbaceous plants to more severe freezing in some northern temperate regions. Legumes are a key functional group that may exhibit lower freezing tolerance than other species in these regions, but this trend has been observed only for non-native legumes. Our aim was to confirm if this trend is restricted to non-native legumes or whether native legumes in these regions also exhibit low freezing tolerance. METHODS: First, we transplanted legumes (five non-native species and four native species) into either an old field (non-native) or a prairie (native) and used snow removal to expose the plots to increased soil freezing. Second, we grew plants in mesocosms (old field) and pots (prairie species) and exposed them in controlled environment chambers to a range of freezing treatments (control, 0, -5 or -10 °C) in winter or spring. We assessed freezing responses by comparing differences in biomass, cover and nodulation between freezing (or snow removal) treatments and controls. KEY RESULTS: Among legume species, lower freezing tolerance was positively correlated with a lower proportion of nodulated plants and active nodules, and under controlled conditions, freezing-induced reductions in above-ground biomass were lower on average in native legumes than in non-native legumes. Nevertheless, both non-native and native legumes (except Desmodium canadense) exhibited greater reductions in biomass in response to increased freezing than their non-leguminous neighbours, both in controlled environments and in the field. CONCLUSIONS: These results demonstrate that both native and non-native legumes exhibit low freezing tolerance relative to other herbaceous species in northern temperate plant communities. By reducing legume biomass and nodulation, increased soil freezing could reduce nitrogen inputs into these systems.

Hormonal profiles in dormant turions of 22 aquatic plant species: do they reflect functional or taxonomic traits?

BACKGROUND AND AIMS: Turions are vegetative, dormant overwintering organs formed in aquatic plants in response to unfavourable ecological conditions. Contents of cytokinin (CK), auxin metabolites and abscisic acid (ABA) as main growth and development regulators were compared in innately dormant autumnal turions of 22 aquatic plant species of different functional ecological or taxonomic groups with those in non-dormant winter apices in three aquatic species and with those in spring turions of four species after their overwintering. METHODS: The hormones were analysed in miniature turion samples using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry. KEY RESULTS: In innately dormant turions, the total contents of each of the four main CK types, biologically active forms and total CKs differed by two to three orders of magnitude across 22 species; the proportion of active CK forms was 0.18-67 %. Similarly, the content of four auxin forms was extremely variable and the IAA proportion as the active form was 0.014-99 %. The ABA content varied from almost zero to 54 µmol kg-1 dry weight and after overwintering it usually significantly decreased. Of all functional traits studied, hormone profiles depended most on the place of turion sprouting (surface vs bottom) and we suggest that this trait is crucial for turion ecophysiology. CONCLUSIONS: The key role of ABA in regulating turion dormancy was confirmed. However, the highly variable pattern of the ABA content in innately dormant and in overwintered turions indicates that the hormonal mechanism regulating the innate dormancy and its breaking in turions is not uniform within aquatic plants.

Individual quality overwrites carry-over effects across the annual cycle of a long-distance migrant.

In seasonal environments, the fitness of animals depends upon the successful integration of life-history stages throughout their annual cycle. Failing to do so can lead to negative carry-over effects where individuals are transitioning into the next season in different states, consequently affecting their future performance. However, carry-over effects can be masked by individual quality when individuals vary in their efficiency at acquiring resources year after year (i.e. 'quality'), leading to cross-seasonal consistency in individual performance. Here we investigated the relative importance of carry-over effects and individual quality in determining cross-seasonal interactions and consequences for breeding success over the full annual cycle of a migratory seabird (black-legged kittiwake Rissa tridactyla). We monitored the reproduction and annual movement of kittiwakes over 13 years using geolocators to estimate their breeding success, distribution and winter energy expenditure. We combined this with an experimental approach (clutch removal experiment, 2 years) to manipulate the reproductive effort irrespective of individual quality. Piecewise path analyses showed that successful breeders reproduced earlier and were more likely to breed successfully again the following year. This positive interaction among consecutive breeding stages disappeared after controlling for individual quality, suggesting that quality was dominant in determining seasonal interactions. Moreover, controlling experimentally for individual quality revealed underlying carry-over effects that were otherwise masked by quality, with breeding costs paid in higher energy expenditure and delayed onset of reproduction. We highlight the need to combine an experimental approach along with long-term data while assessing apparent carry-over effects in wild animals, and their potential impact on fitness and population demography.

Fruit wings accelerate germination in Anacyclus clavatus.

PREMISE: The lateral membranous expansions of fruits, commonly referred to as wings, have long been theorized to serve only dispersal functions. Alternatively, because winged fruits typically have earlier seed germination than unwinged fruits, we hypothesized that wings could increase the contact surface with water, ultimately triggering earlier germination. METHODS: We investigated this alternative hypothesis by exploring the potential role of fruit wings on germination in the heterocarpic species Anacyclus clavatus (Desf.) Pers. (Asteraceae), which produces both winged and unwinged fruits. First, we measured the speed and degree of water absorption in winged and unwinged fruits. Second, we investigated the effects of wings on germination performance, by either reducing wing size or by preventing water absorption by sealing wings with wax. Next, we tested the influence of water availability on the germination performance of winged and unwinged fruits by reducing the water potential. RESULTS: Winged fruits absorbed more water at a faster rate than unwinged fruits. The sealing of wings delayed germination, whereas germination time was not significantly altered by wing cutting. The restriction of water availability by decreasing water potential significantly delayed seed germination of unwinged fruits, whereas winged fruits remained unaffected. CONCLUSIONS: Altogether, our results support the effect of wings on germination and cast doubt on the unique role of wings in dispersal. Whether or not wings contribute to dispersal, we propose that they also improve seed germination and seedling establishment by facilitating water absorption after the release from their mother plants.

Antigenic similarities and clinical cross-protection between variant and classic non-viscous strains of Moritella viscosa in Atlantic salmon in Norway.

Moritella viscosa (M. viscosa) is one of the major etiological agents of winter-ulcers in Atlantic salmon (Salmo salar) in Norway. Outbreaks of ulcerative disease in farmed fish occur across the North Atlantic region, causing reduced animal welfare and economical challenges, and are of hindrance for sustainable growth within the industry. Commercially available multivalent core vaccines containing inactivated bacterin of M. viscosa reduce mortality and clinical signs related to winter ulcer disease. It has previously been described two major genetic clades within M. viscosa, typical (hereafter referred to as classic) and variant, based on gyrB sequencing. In addition, there are phenotypical traits such as viscosity that may differ between different types of isolates. Western blot using salmon plasma showed that classic non-viscous strains are antigenically different from the classic viscous type included in core vaccines. Further, Western blot also showed that there are similarities in binding patterns between Norwegian variant and classic non-viscous isolates, indicating they may be antigenically related. Vaccination-challenge trials using Norwegian gyrB-classic non-viscous isolates of M. viscosa, demonstrate that the isolates from the classic clade that are included in current commercial multivalent core vaccines, provide limited cross protection against the emerging non-viscous strains. However, a vaccine recently approved for marketing authorization in Norway, containing inactivated antigen of a variant M. viscosa strain, demonstrates reduced mortality as well as clinical signs caused by infections with the classic non-viscous M. viscosa isolated from outbreaks in Norwegian salmon farms. The study shows that there are antigenic similarities between variant and classic non-viscous types of M. viscosa, and these similarities are mirrored in the observed cross-protection in vaccination-challenge trials.

Quantifying HONO Production from Nitrate Photolysis in a Polluted Atmosphere.

The photolysis of particulate nitrate (pNO3-) has been suggested to be an important source of nitrous acid (HONO) in the troposphere. However, determining the photolysis rate constant of pNO3- (jpNO3-) suffers from high uncertainty. Prior laboratory measurements of jpNO3- using aerosol filters have been complicated by the "shadow effect"─a phenomenon of light extinction within aerosol layers that potentially skews these measurements. We developed a method to correct the shadow effect on the photolysis rate constant of pNO3- for HONO production (jpNO3- â†’ HONO) using aerosol filters with identical chemical compositions but different aerosol loadings. We applied the method to quantify jpNO3- â†’ HONO over the North China Plain (NCP) during the winter haze period. After correcting for the shadow effect, the normalized average jpNO3- â†’ HONO at 5 °C increased from 5.89 × 10-6 s-1 to 1.72 × 10-5 s-1. The jpNO3- â†’ HONO decreased with increasing pH and nitrate proportions in PM2.5 and had no correlation with nitrate concentrations. A parametrization for jpNO3- â†’ HONO was developed for model simulation of HONO production in NCP and similar environments.