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BackgroundPlant volatiles play an important role in both plant-pollinator and plant-herbivore interactions. Intraspecific polymorphisms in volatile production are ubiquitous, but studies that explore underlying differential gene expression are rare. Oenothera harringtonii populations are polymorphic in floral emission of the monoterpene (R)-(-)-linalool; some plants emit (R)-(-)-linalool (linalool+ plants) while others do not (linalool-plants). However, the genes associated with differential production of this floral volatile in Oenothera are unknown. We used RNA-Seq to broadly characterize differential gene expression involved in (R)-(-)-linalool biosynthesis. To identify genes that may be associated with the polymorphism for this trait, we used RNA-Seq to compare gene expression in six different Oenothera harringtonii tissues from each of three linalool+ and linalool-plants.ResultsThree clusters of differentially expressed genes were enriched for terpene synthase activity: two were characterized by tissue-specific upregulation and one by upregulation only in plants with flowers that produce (R)-(-)-linalool. A molecular phylogeny of all terpene synthases identified two putative (R)-(-)-linalool synthase transcripts in Oenothera harringtonii, a single allele of which is found exclusively in linalool+ plants.ConclusionsBy using a naturally occurring polymorphism and comparing different tissues, we were able to identify genes putatively involved in the biosynthesis of (R)-(-)-linalool. Expression of these genes in linalool-plants suggests a regulatory polymorphism, rather than a population-specific loss-of-function allele. Additional terpene biosynthesis-related genes that are up-regulated in plants that emit (R)-(-)-linalool may be associated with herbivore defense, suggesting a potential economy of scale between plant reproduction and defense.

Floral scents act as long-distance signals to attract pollinators, but volatiles emitted from the vegetation and neighboring plant community may modify this mutualistic communication system. What impact does the olfactory background have on pollination systems and their evolution? We consider recent behavioral studies that address the context of when and where volatile backgrounds influence a pollinator's perception of floral blends. In parallel, we review neurophysiological studies that show the importance of blend composition and background in modifying the representation of floral blends in the pollinator brain, as well as experience-dependent plasticity in increasing the representation of a rewarding odor. Here, we suggest that the efficacy of the floral blend in different environments may be an important selective force shaping differences in pollinator olfactory receptor expression and underlying neural mechanisms that mediate flower visitation and plant reproductive isolation.

Eicosanoids comprise a diverse group of bioactive lipids which orchestrate inflammation, immunity and tissue homeostasis, and whose dysregulation has been implicated in carcinogenesis. Among the various eicosanoid metabolic pathways, studies of their role in endometrial cancer (EC) have very much been confined to the COX‐2 pathway. This study aimed to determine changes in epithelial eicosanoid metabolic gene expression in endometrial carcinogenesis, to integrate these with eicosanoid profiles in matched clinical specimens and, finally, to investigate the prognostic value of candidate eicosanoid metabolic enzymes. Eicosanoids and related mediators were profiled using liquid chromatography‐tandem mass spectrometry in fresh frozen normal, hyperplastic and cancerous (Types I and II) endometrial specimens (n=192). Sample‐matched epithelia were isolated by laser capture microdissection and whole genome expression analysis was performed using microarrays. Integration of eicosanoid and gene expression data showed that the accepted paradigm of increased COX‐2 mediated prostaglandin production does not apply in EC carcinogenesis. Instead, there was evidence for decreased PGE2/PGF2α inactivation via 15‐hydroxyprostaglandin dehydrogenase (HPGD) in Type II ECs. Increased expression of 5‐lipoxygenase (ALOX5) mRNA was also identified in Type II ECs, together with proportional increases in its product, 5‐hydroxyeicosatetraenioic acid (5‐HETE). Decreased HPGD and elevated ALOX5 mRNA expression were associated with adverse outcome, which was confirmed by immunohistochemical tissue microarray analysis of an independent series of EC specimens (n=419). While neither COX‐1 nor COX‐2 protein expression had prognostic value, low HPGD combined with high ALOX5 expression associated with the worst overall and progression‐free survival. These findings highlight HPGD and ALOX5 as potential therapeutic targets in aggressive EC subtypes.

Presynaptic resting Ca(2+) influences synaptic vesicle (SV) release probability. Here, we report that a TRPV channel, Inactive (Iav), maintains presynaptic resting [Ca(2+)] by promoting Ca(2+) release from the endoplasmic reticulum in Drosophila motor neurons, and is required for both synapse development and neurotransmission. We find that Iav activates the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin, which is essential for presynaptic microtubule stabilization at the neuromuscular junction. Thus, loss of Iav induces destabilization of presynaptic microtubules, resulting in diminished synaptic growth. Interestingly, expression of human TRPV1 in Iav-deficient motor neurons rescues these defects. We also show that the absence of Iav causes lower SV release probability and diminished synaptic transmission, whereas Iav overexpression elevates these synaptic parameters. Together, our findings indicate that Iav acts as a key regulator of synaptic development and function by influencing presynaptic resting [Ca(2+)].

Circadian patterns of activity are considered ubiquitous and adaptive, and are often invoked as a mechanism for temporal niche partitioning. Yet, comparisons of rhythmic behavior in related animal species are uncommon. This is particularly true of Lepidoptera (butterflies and moths), in which studies of whole-animal patterns of behavior are far outweighed by examinations of tissue-specific molecular clocks. Here, we used a comparative approach to examine the circadian patterns of flight behavior in Manduca sexta and Hyles lineata, two distantly related species of hawkmoth (Sphingidae). By filming isolated, individual animals we were able to examine rhythmic locomotor (flight) activity at the species level as well as at the level of the individual sexes, and in the absence of interference from social interaction. Our results confirm classic descriptions of strictly nocturnal behavior in M. sexta and demonstrate a dramatically different activity pattern in H. lineata. Furthermore, we show distinct species and sex-specific differences in the maintenance of the endogenous rhythm under conditions of constant darkness. In both species, female activity peaks in advance of males, whereas male activity coincides with periods of female sexual receptivity. This suggests a role for circadian patterns of locomotor activity in synchronizing periods of sexual receptivity between the sexes.

Herbivory is viewed as a major driver of plant evolution and the most important energy pathway from plants to higher trophic levels. Therefore, understanding patterns of herbivory on plants remains a key focus in evolution and ecology. The evolutionary impacts of leaf herbivory include altering plant fitness, local adaptation, the evolution of defenses, and the diversification of plants as well as natural enemies. Leaf herbivory also impacts ecological processes such as plant productivity, community composition, and ecosystem nutrient cycling. Understanding the impact of herbivory on these ecological and evolutionary processes requires species-specific, as opposed to community-level, measures of herbivory. In addition, species-specific data enables the use of modern comparative methods to account for phylogenetic non-independence. Although hundreds of studies have measured natural rates of leaf consumption, we are unaware of any accessible compilation of these data. We created such a data set to provide the raw data needed to test general hypotheses relating to plant–herbivore interactions and to test the influence of biotic and abiotic factors on herbivory rates across large spatial scales. A large repository will make this endeavor more efficient and robust. In total, we compiled 2641 population-level measures for either annual or daily rates of leaf herbivory across 1145 species of vascular plants collected from 189 studies. All damage measures represent natural occurrences of herbivory that span numerous angiosperm, gymnosperm, and fern species. To enable researchers to explore the causes of variation in herbivory and how these might interact, we added information about the study sites including: geolocation, climate classification, habitat descriptions (e.g., seashore, grassland, forest, agricultural fields), and plant trait information concerning growth form and duration (e.g., annual vs. perennial). We also included extensive details of the methodology used to measure leaf damage, including seasons and months of sampling, age of leaves, and the method used to estimate percentage area missing. We anticipate that these data will make it possible to test important hypotheses in the plant–herbivore literature, including the plant apparency hypothesis, the latitudinal-herbivory defense hypothesis, the resource availability hypothesis, and the macroevolutionary escalation of defense hypothesis.