Apple flavor is characterized by combinations of ester compounds, which increase markedly during fruit ripening. The final step in ester biosynthesis is catalyzed by alcohol acyl transferases (AATs) ...that use coenzyme A (CoA) donors together with alcohol acceptors as substrates. The gene MpAAT1, which produces a predicted protein containing features of other plant acyl transferases, was isolated from Malus pumila (cv. Royal Gala). The MpAAT1 gene is expressed in leaves, flowers and fruit of apple. The recombinant enzyme can utilize a range of alcohol substrates from short to medium straight chain (C3–C10), branched chain, aromatic and terpene alcohols. The enzyme can also utilize a range of short to medium chain CoAs. The binding of the alcohol substrate is rate limiting compared with the binding of the CoA substrate. Among different alcohol substrates there is more variation in turnover compared with Km values. MpAAT1 is capable of producing many esters found in Royal Gala fruit, including hexyl esters, butyl acetate and 2‐methylbutyl acetate. Of these, MpAAT1 prefers to produce the hexyl esters of C3, C6 and C8 CoAs. For the acetate esters, however, MpAAT1 preference depends upon substrate concentration. At low concentrations of alcohol substrate the enzyme prefers utilizing the 2‐methylbutanol over hexanol and butanol, while at high concentrations of substrate hexanol can be used at a greater rate than 2‐methylbutanol and butanol. Such kinetic characteristics of AATs may therefore be another important factor in understanding how the distinct flavor profiles of different fruit are produced during ripening.
Premise of research. Newly recognized compression fossils of fertile leptosporangiate ferns assignable to Dennstaedtia Bernh. (Dennstaedtiaceae) and Hymenophyllum Sm. (Hymenophyllaceae) are described ...from the latest early Eocene floras of the Okanogan Highlands, British Columbia, Canada, and northeastern Washington.
Methodology. Specimens were photographed with reflected light microscopy and were studied morphologically in comparison with related fossil and extant forms. Focus-shift stacking was used to layer photos of some specimens. Some were photographed with polarized light. The holotype specimen of Dennstaedtia christophelii sp. nov. was also studied with environmental scanning electron microscopy.
Pivotal results. We describe D. christophelii sp. nov. (Dennstaedtiaceae) and Hymenophyllum axsmithii sp. nov. (Hymenophyllaceae) on the basis of vegetative and fertile remains of fragmentary fronds. Specimens of D. christophelii are one-pinnate-pinnatifid to bipinnate and bear frequent marginal round sori in cuplike indusia on small crenulate to dissected pinnae. Sporangia each have a prominent annulus with approximately six to eight long cells visible. Hymenophyllum axsmithii has the type of lamina cutting, sorus position, alate rachis, sorus shape, and venation corresponding to Hymenophyllum, subgenus Sphaerocionium (Hymenophyllaceae). The numerous sporangia per sori each bear a prominent annulus, and 7–10 casts of spores are noted in some sporangia.
Conclusions. These fossils document the occurrence of leptosporangiate fern diversity in the early Eocene Okanogan Highlands floras. Dennstaedtia christophelii represents one of several occurrences of Dennstaedtiaceae in the Eocene. Hymenophyllum axsmithii is the first unequivocal member of Hymenophyllaceae to be reported from these diverse plant and insect assemblages from lacustrine and swamp settings under warm temperate climates of the latest early Eocene.
Increasing consumer demand for natural flavours and fragrances has driven up prices and increased pressure on natural resources. A shift in consumer preference towards more sustainable and economical ...sources of these natural additives and away from synthetic production has encouraged research into alternative supplies of these valuable compounds. Solid-state fermentation processes support the natural production of secondary metabolites, which represents most flavour and aroma compounds, while agro-industrial by-products are a low-value waste stream with a high potential for adding value. Accordingly, four filamentous fungi species with a history of use in the production of fermented foods and food additives were tested to ferment nine different agro-industrial by-products. Hundreds of volatile compounds were produced and identified using headspace (HS) solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Four compounds of interest, phenylacetaldehyde, methyl benzoate, 1-octen-3-ol, and phenylethyl alcohol, were extracted and quantified. Preliminary yields were encouraging compared to traditional sources. This, combined with the low-cost substrates and the high-value natural flavours and aromas produced, presents a compelling case for further optimisation of the process.
Invasive forest pests are damaging North American forests, and their intracontinental spread can be accelerated through the movement of infested firewood. We assessed the general public’s awareness, ...attitudes, and perceptions of forest health issues and identified potential strategies for more effective delivery of information about invasive forest pests and firewood transport. We analyzed data obtained from five surveys conducted between 2005 and 2016 (n = 4,840). Awareness, choice of mode of information, and trusted messenger were predicted using linear regression models based on selected independent variables including age, race, gender, education level, and the participant’s type of residential area. Overall, awareness regarding invasive forest pests was low among participants. Participants stated they would be most likely to pay attention to a flyer handed out when entering a state or national park or receiving an email after making a campsite reservation. State forestry agencies were the most believable source of information regarding forest health issues. For the modes of information listed on the survey, older participants and those with higher education levels were more likely to have greater awareness levels and to pay attention, while female and younger participants were more likely to indicate they believed the messengers. We conclude that awareness is key for modifying behavior related to firewood transport; as such, educational campaigns with effective messaging strategies could be a successful approach to reducing the movement of firewood by members of the public.
During the early to middle Eocene, a mid‐to‐high latitudinal position and enhanced hydrological cycle in Australia would have contributed to a wetter and “greener” Australian continent where today ...arid to semi‐arid climates dominate. Here, we revisit 12 southern Australian plant megafossil sites from the early to middle Eocene to generate temperature, precipitation, and seasonality paleoclimate estimates, net primary productivity (NPP), and vegetation type, based on paleobotanical proxies and compare them to early Eocene global climate models. Temperature reconstructions are uniformly subtropical (mean annual, summer, and winter mean temperatures 19–21°C, 25–27°C, and 14–16°C, respectively), indicating that southern Australia was ∼5°C warmer than today, despite a >20° poleward shift from its modern geographic location. Precipitation was less homogeneous than temperature, with mean annual precipitation of ∼60 cm over inland sites and >100 cm over coastal sites. Precipitation may have been seasonal with the driest month receiving 2–7× less than the mean monthly precipitation. Proxy‐model comparison is favorable with a 1,680 ppm CO2 concentration. However, individual proxy reconstructions can disagree with models as well as with each other. In particular, seasonality reconstructions have systemic offsets. NPP estimates were higher than modern, implying a more homogenously “green” southern Australia in the early to middle Eocene when this part of Australia was at 48–64°S and larger carbon fluxes to and from the Australian biosphere. The most similar modern vegetation type is modern‐day eastern Australian subtropical forest, although the distance from coast and latitude may have led to vegetation heterogeneity.
Plain Language Summary
Australia today is dominated by arid environments, with sparse shrubland or grassland vegetation, and forest biomes limited to areas with abundant moisture supply. These arid environments have low primary productivity and store relatively little carbon. Examination of 12 early to middle Eocene (55–40 million years old) fossil floras shows that southern Australia at that time was much “greener.” In a globally warmer world and poleward positioning of southern Australia, southward of mid‐latitude high‐pressure systems, rainfall in now arid environments was much higher. What is now almost barren landscapes would have supported a much more luxurious forested biome. As a result, primary productivity was enhanced and on‐land carbon storage would have been much higher as well. This research shows that in ancient greenhouse worlds high temperatures in addition to a more active hydrological cycle can lead to an increase in carbon storage and fluxes of the terrestrial biosphere.
Key Points
Early Eocene southern Australia average temperatures were over 5°C warmer than today, despite being further south than today
Average rainfall was much higher than today, with 60 cm yr−1 inland to >100 cm yr−1 closer to the coast
Southern Australia was more homogeneously green and productive during the Eocene, in places where today arid shrub‐ and grasslands dominate
The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of ...SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 millionfCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface waterfCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: 10.1594/PANGAEA.849770. The gridded products are available here: 10.3334/CDIAC/OTG.SOCAT_V3_GRID.
•Wine alcohol significantly influences sensory properties and volatile chemistry.•Untargeted volatile profiles used to model wine flavour intensities.•First application of sensory reference samples ...for variable selection.•Wines and sensory references have volatile compounds in common.
The relationship between wine flavour and wine volatile composition is well recognised, however with thousands of compounds in wine the exact nature of individual contributions may be hard to determine due to synergistic and masking effects. Untargeted chemical analyses coupled with descriptive sensory and partial least squares regression modelling can help unravel interactions to identify groups of compounds that contribute to sensory properties. Variable selection is often applied prior to modelling to eliminate irrelevant variables. In this study, sensory references used to train the sensory panel were chemically analysed and employed to reduce the number of variables used to construct the models. This novel variable selection approach was compared against the inclusion of all variables and the most commonly applied variable selection method – analysis of variance. Models constructed from variables present in sensory references performed similarly to other models and identified interesting groups of compounds to investigate further.
A reconstruction of terrestrial temperature and precipitation for the New Zealand landmass over the past ∼30 million years is produced using pollen data from >2000 samples lodged in the New Zealand ...Fossil Record Electronic Database and modern climate data of nearest living relatives. The reconstruction reveals a warming trend through the late Oligocene to early Miocene, peak warmth in the middle Miocene, and stepwise cooling through the late Neogene. Whereas the regional signal in our reconstruction includes a ∼5–10° northward tectonic drift, as well as an increase in high altitude biomes due to late Neogene and Pliocene uplift of the Southern Alps, the pattern mimics inferred changes in global ice extent, which suggests that global drivers played a major role in shaping local vegetation. Importantly, seasonal temperature estimates indicate low seasonality during the middle Miocene, and that subsequent Neogene cooling was largely due to cooler winters. We suggest that this may reflect increased Subantarctic influence on New Zealand vegetation as the climate cooled.
•New Zealand climate since Oligocene time is inferred from >2300 pollen samples.•Oligocene warming until peak warmth of middle Miocene, cooling through late Neogene.•Seasonality increased after middle Miocene, as winters cooled through the Neogene.•Record reflects greater range of biomes following late Neogene mountain uplift.
shared chemical basis of avian host–parasite egg colour mimicry Igic, Branislav; Cassey, Phillip; Grim, Tomáš ...
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
03/2012, Letnik:
279, Številka:
1731
Journal Article
Recenzirano
Odprti dostop
Avian brood parasites lay their eggs in other birds' nests and impose considerable fitness costs on their hosts. Historically and scientifically, the best studied example of circumventing host ...defences is the mimicry of host eggshell colour by the common cuckoo (Cuculus canorus). Yet the chemical basis of eggshell colour similarity, which impacts hosts' tolerance towards parasitic eggs, remains unknown. We tested the alternative scenarios that (i) cuckoos replicate host egg pigment chemistry, or (ii) cuckoos use alternative mechanisms to produce a similar perceptual effect to mimic host egg appearance. In parallel with patterns of similarity in avian-perceived colour mimicry, the concentrations of the two key eggshell pigments, biliverdin and protoporphyrin, were most similar between the cuckoo host-races and their respective hosts. Thus, the chemical basis of avian host–parasite egg colour mimicry is evolutionarily conserved, but also intraspecifically flexible. These analyses of pigment composition reveal a novel proximate dimension of coevolutionary interactions between avian brood parasites and hosts, and imply that alternative phenotypes may arise by the modifications of already existing biochemical and physiological mechanisms and pathways.
The level of linoleic acid in the Sauvignon blanc (SB) grape juice affects the development of different aroma compounds during fermentation by Saccharomyces cerevisiae EC1118, including key varietal ...thiols such as 3-mercaptohexanol (3MH) and 3-mercaptohexyl acetate (3MHA). However, it is still unknown if linoleic acid would affect in a similar way other commonly used S. cerevisiae wine strains. Here we investigated the effect of grape juice linoleic acid on the development of aroma compounds and other metabolites of SB wines using different wine yeast strains: EC1118, AWRI796 and VIN13. Linoleic acid clearly affected the levels of acetylated aroma compounds, several amino acids, and antioxidant molecules, independent of yeast strain, but the production of 3MH was affected by linoleic acid in a strain-specific manner. Moreover, the supplementation of deuterium-labelled 3MH also affected the production of varietal thiols in a strain-specific way. Linoleic acid reduced the acetylation process probably by inhibiting an acetyltransferase, an effect that was independent of the yeast strain. However, regulation of the 3MH biosynthesis is strain-specific, which suggests a mindful consideration not only towards the wine yeast but also to the linoleic acid concentration in the grape juice in order to obtain the desired wine aroma characteristics.
The level of linoleic acid in Sauvignon blanc grape juice affects the development of different aroma compounds during wine fermentation by different strains of Saccharomyces cerevisiae.
Graphical Abstract Figure.
The level of linoleic acid in Sauvignon blanc grape juice affects the development of different aroma compounds during wine fermentation by different strains of Saccharomyces cerevisiae.
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