Real‐time monitoring of herbivore induced volatile emissions in the field

When plants are damaged by herbivorous insects they emit a blend of volatile organic compounds (VOCs) which include a range or terpenoids and green leaf volatiles (GLVs) formed via different metabolic pathways. The precise timing of these emissions upon the onset of herbivore feeding has not been fully elucidated, and the information that is available has been mainly obtained through laboratory based studies. We investigated emissions of VOCs from Populus tremula L. ×P. tremuloides Michx. during the first 20 h of feeding by Epirrita autumnata (autumnal moth) larvae in a field site. The study was conducted using Proton Transfer Reaction‐Mass Spectrometry (PTR‐MS) to measure emissions online, with samples collected for subsequent analysis by complementary gas chromatography‐mass spectrometry for purposes of compound identification. GLV emission peaks occurred sporadically from the outset, indicating herbivore activity, while terpene emissions were induced within 16 h. We present data detailing the patterns of monoterpene (MT), GLV and sesquiterpene (SQT) emissions during the early stages of herbivore feeding showing diurnal MT and SQT emission that is correlated more with temperature than light. Peculiarities in the timing of SQT emissions prompted us to conduct a thorough characterization of the equipment used to collect VOCs and thus corroborate the accuracy of results. A laboratory based analysis of the throughput of known GLV, MT and SQT standards at different temperatures was made with PTR‐MS. Enclosure temperatures of 12, 20 and 25°C had little influence on the response time for dynamic measurements of a GLV or MT. However, there was a clear effect on SQT measurements. Elucidation of emission patterns in real‐time is dependent upon the dynamics of cuvettes at different temperatures.     

Mycorrhiza formation is not needed for early growth induction and growth-related changes in polyamines in Scots pine seedlings in vitro

Ectomycorrhizal (ECM) fungi have been shown to improve growth of the host plant before the formation of physical ECM structures, i.e. during the so-called pre-mycorrhizal phase. In the present study, changes in growth and the concentrations of individual polyamines (PAs) were followed during the mycorrhiza formation in Scots pine (Pinus sylvestris) seedlings in the presence of two ECM fungi, Pisolithus tinctorius and Paxillus involutus. The two fungus stains were chosen because they differed in infection characteristics as well as in PA and auxin production. The results were compared to our earlier study with two Suillus variegatus strains forming ECMs with Scots pine seedlings in vitro. Paxillus was not able to form ECMs whereas Pisolithus formed ECM association with Scots pine seedlings within two weeks. However, Paxillus enhanced the growth of the seedlings more than Pisolithus. Paxillus also increased putrescine (Put) concentrations of the seedlings in the pre-mycorrhizal phase much more than Pisolithus. A similar trend was observed in the free spermidine (Spd) in stems, whereas in the needles Paxillus decreased free Spd concentration. Pisolithus caused a threefold greater increase in root free Spd than Paxillus. Effects of Paxillus on the growth and PA fluctuation, excluding root free Spd, of the host plant resembled that observed in our previous in vitro study on S. variegatus–Scots pine interaction. Therefore, changes in specific PA concentrations in the pre-mycorrhizal phase seem to be related to growth induction by the ECM fungus rather than to mycorrhiza formation. Moreover, we suggest that growth induction in host plants is not necessarily followed by ECM formation.     

Variable responses of natural enemies to Salix triandra phenotypes with different secondary chemistry

Plant phenotypes often differ in their resistance to natural enemies, but the mechanism for this has seldom been identified. The aim of this study was to determine if the spatial patterns of phenotype use of a highly specialized insect herbivore (the galling sawfly Pontania triandrae ) in a natural willow population can be related to phenotypic variation in plant secondary chemistry. Furthermore, we tested if traits that confer resistance to one type of natural enemy, i.e. the galling sawfly, also confer resistance to others, in our case a leaf beetle Gonioctena linnaeana and the rust fungus Melampsora amygdalinae . We identified 18 phenotypes with high and 18 phenotypes with low gall density in our field population and determined gall densities, the degree of leaf damage and rust infection on each phenotype and collected leaves for chemical analyses. The concentration of phenolics was higher in phenotypes with high density of galls suggesting that this galling sawfly may use phenolics as oviposition cues. Rust infection showed the opposite pattern, with lower levels on clones with high concentration of phenolics, while leaf damage by G. linnaeana did not differ between clone types. This indicates that these important natural enemies may assert divergent selection on willow phenotypes and that this might provide a mechanism for maintaining phenotypic variation within willow populations.     

Suillus variegatus causes significant changes in the content of individual polyamines and flavonoids in Scots pine seedlings during mycorrhiza formation in vitro

Changes in the concentrations of individual flavonoids and polyamines (PAs) in Scots pine (Pinus sylvestris L.) cotyledonary seedlings were studied during the establishment of an ectomycorrhizal (ECM) symbiosis with two Suillus variegatus strains in vitro. Both flavonoids and PAs were analysed after 3, 7, and 14 d in dual culture, and changes in concentrations were compared with growth of the seedlings. Both S. variegatus strains caused similar responses in Scots pine seedlings. Free putrescine accumulated immediately but only transiently after inoculation. This was followed by continuous accumulation of PA conjugates in needles and stems, and free spermidine and spermine in roots, which was accompanied by mycorrhiza formation and improved growth. The fungi induced lateral root formation and main root and primary needle elongation. Inoculation caused no qualitative changes in flavonoid composition, while quantitative changes in flavonols, catechins, and condensed tannins were observed in shoots during mycorrhiza formation. These results indicate that in this in vitro system conjugated PAs and specific flavonoids, generally related to the plant's defence reactions, did not play a major role in the regulation of the establishment of the ectomycorrhizal (ECM) symbiosis in Scots pine roots. The results also clearly show that positive growth responses in shoots and roots due to S. variegatus were supported by different and highly specific changes in the synthesis of both primary and secondary metabolites in these parts of the seedling.     

Serum activity of dipeptidyl peptidase IV (DPPIV; EC 3.4.14.5) in breast-fed infants with symptoms of allergy

Beta-casomorphins, opioid peptides present in mother's milk, are a good substrate for DPPIV (EC 3.4.14.5) which is a major factor limiting the half-life of biologically active peptides. Serum DPPIV activity of two groups of infants (healthy and atopic dermatitis) and contents of beta-casomorphin-5 and -7 in their mothers' milk were determined in the study. We have found correlation between those two parameters in the group of children with atopic dermatitis syndromes, while no such a correlation was found in the control group.     

Changes of beta-casomorphin content in human milk during lactation

Milk is the best, complete food important for the development and nourishment of a neonate. Except for nutrients, milk contains biologically active opioid peptides derived from beta-casein, named beta-casomorphins (BCMs), which can exert effects in the gastrointestinal tract as well as in the whole body of neonates. The content of beta-casomorphins in human milk during maturation phases has not been studied so far. The aim of this study was to determine the content of beta-casomorphin-5 and -7 in human milk in different phases of lactation. A significantly higher concentration of both beta-casomorphins was found in colostrum than in mature milk. The concentration of beta-casomorphin in milk collected in the second month of lactation was similar to the level obtained in the fourth month of lactation. The content of beta-casomorphins in human milk was observed with the period of lactation. The level of opioid peptides may depend on the function of these peptides in neonate's body and may be associated with the maturation process.     

On statistical inference for the random set generated Cox process with set-marking

Cox point process is a process class for hierarchical modelling of systems of non-interacting points in Rd under environmental heterogeneity which is modelled through a random intensity function. In this work a class of Cox processes is suggested where the random intensity is generated by a random closed set. Such heterogeneity appears for example in forestry where silvicultural treatments like harvesting and site-preparation create geometrical patterns for tree density variation in two different phases. In this paper the second order property, important both in data analysis and in the context of spatial sampling, is derived. The usefulness of the random set generated Cox process is highly increased, if for each point it is observed whether it is included in the random set or not. This additional information is easy and economical to obtain in many cases and is hence of practical value; it leads to marks for the points. The resulting random set marked Cox process is a marked point process where the marks are intensity-dependent. The problem with set-marking is that the marks are not a representative sample from the random set. This paper derives the second order property of the random set marked Cox process and suggests a practical estimation method for area fraction and covariance of the random set and for the point densities within and outside the random set. A simulated example and a forestry example are given.     

Do Insectivorous Birds use Volatile Organic Compounds from Plants as Olfactory Foraging Cues? Three Experimental Tests

Some insectivorous birds orient towards insect‐defoliated trees even when they do not see the foliar damage or the herbivores. There are, however, only a few studies that have examined the mechanisms behind this foraging behaviour. Previous studies suggest that birds can use olfactory foraging cues (e.g. volatile organic compounds (VOCs) emitted by defoliated plants), indirect visual cues or a combination of the two sensory cues. VOCs from insect‐defoliated plants are known to attract natural enemies of herbivores, and researchers have hypothesized that VOCs could also act as olfactory foraging cues for birds. We conducted three experiments across a range of spatial scales to test this hypothesis. In each experiment, birds were presented with olfactory cues and their behavioural responses or foraging outcomes were observed. In the first experiment, two different VOC blends, designed to simulate the volatile emissions of mountain birch (Betula pubescens ssp. czerepanovii) after defoliation by autumnal moth (Epirrita autumnata) larvae, were used in behavioural experiments in aviaries with pied flycatchers (Ficedula hypoleuca). The second experiment was a field‐based trial of bird foraging efficiency; the same VOC blends were applied to mountain birches, silver birches (B. pendula) and European white birches (B. pubescens) with plasticine larvae attached to the trees to serve as artificial prey for birds and provide a means to monitor predation rate. In the third experiment, the attractiveness of silver birch saplings defoliated by autumnal moth larvae versus intact controls was tested with great tits (Parus major) and blue tits (Cyanistes caeruleus) in an aviary. Birds did not orient towards either artificial or real trees with VOC supplements or towards herbivore‐damaged saplings when these saplings and undamaged alternatives were hidden from view. These findings do not support the hypothesis that olfactory foraging cues are necessary in the attraction of birds to herbivore‐damaged trees.     

Different metabolic responses of human brown adipose tissue to activation by cold and insulin

We investigated the metabolism of human brown adipose tissue (BAT) in healthy subjects by determining its cold-induced and insulin-stimulated glucose uptake and blood flow (perfusion) using positron emission tomography (PET) combined with computed tomography (CT). Second, we assessed gene expression in human BAT and white adipose tissue (WAT). Glucose uptake was induced 12-fold in BAT by cold, accompanied by doubling of perfusion. We found a positive association between whole-body energy expenditure and BAT perfusion. Insulin enhanced glucose uptake 5-fold in BAT independently of its perfusion, while the effect on WAT was weaker. The gene expression level of insulin-sensitive glucose transporter GLUT4 was also higher in BAT as compared to WAT. In conclusion, BAT appears to be differently activated by insulin and cold; in response to insulin, BAT displays high glucose uptake without increased perfusion, but when activated by cold, it dissipates energy in a perfusion-dependent manner.     

Characterizing associations and SNP-environment interactions for GWAS-identified prostate cancer risk markers--results from BPC3

Genome-wide association studies (GWAS) have identified multiple single nucleotide polymorphisms (SNPs) associated with prostate cancer risk. However, whether these associations can be consistently replicated, vary with disease aggressiveness (tumor stage and grade) and/or interact with non-genetic potential risk factors or other SNPs is unknown. We therefore genotyped 39 SNPs from regions identified by several prostate cancer GWAS in 10,501 prostate cancer cases and 10,831 controls from the NCI Breast and Prostate Cancer Cohort Consortium (BPC3). We replicated 36 out of 39 SNPs (P-values ranging from 0.01 to 10⁻²⁸). Two SNPs located near KLK3 associated with PSA levels showed differential association with Gleason grade (rs2735839, P = 0.0001 and rs266849, P = 0.0004; case-only test), where the alleles associated with decreasing PSA levels were inversely associated with low-grade (as defined by Gleason grade <8) tumors but positively associated with high-grade tumors. No other SNP showed differential associations according to disease stage or grade. We observed no effect modification by SNP for association with age at diagnosis, family history of prostate cancer, diabetes, BMI, height, smoking or alcohol intake. Moreover, we found no evidence of pair-wise SNP-SNP interactions. While these SNPs represent new independent risk factors for prostate cancer, we saw little evidence for effect modification by other SNPs or by the environmental factors examined.