Sequencing of the genome of the butterfly Heliconius melpomene shows that closely related Heliconius species exchange protective colour-pattern genes promiscuously.

/pdf/butterfly-genome-reveals-promiscuous-exchange-of-mimicry-4zck1zwzeb.pdf

Butterfly genome reveals promiscuous exchange of mimicry adaptations among species

Acyltransferases in plants: a good time to be BAHD.

Structure and function of the vomeronasal system: an update

Olfaction: diverse species, conserved principles.

In spite of initial doubts about the reality of ‘talking trees’, plant resistance expression mediated by volatile compounds that come from neighboring plants is now well described. Airborne signals usually improve the resistance of the receiver, but without obvious benefits for the emitter, thus making the evolutionary explanation of this phenomenon problematic. Here, we discuss four possible non-exclusive explanations involving the role of volatiles: in direct defense, as within-plant signals, as traits that synergistically interact with other defenses, and as cues among kin. Unfortunately, there is a lack of knowledge on the fitness consequences of plant communication for both emitter and receiver. This information is crucial to understanding the ecology and evolution of plant communication via airborne cues.

https://www.cell.com/trends/ecology-evolution/pdf/S0169-5347(09)00300-0.pdf

Explaining evolution of plant communication by airborne signals.

Phenolic compounds and methylglyoxal in some New Zealand manuka and kanuka honeys.

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 K(m) 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.

/pdf/an-alcohol-acyl-transferase-from-apple-cv-royal-gala-mpaat1-28py4y3s5q.pdf

An alcohol acyl transferase from apple (cv. Royal Gala), MpAAT1, produces esters involved in apple fruit flavor

Cofactor F420 is a unique electron carrier in a number of microorganisms including Archaea and Mycobacteria. It has been shown that F420 has a direct and important role in archaeal energy metabolism whereas the role of F420 in mycobacterial metabolism has only begun to be uncovered in the last few years. It has been suggested that cofactor F420 has a role in the pathogenesis of M. tuberculosis, the causative agent of tuberculosis. In the absence of a commercial source for F420, M. smegmatis has previously been used to provide this cofactor for studies of the F420-dependent proteins from mycobacterial species. Three proteins have been shown to be involved in the F420 biosynthesis in Mycobacteria and three other proteins have been demonstrated to be involved in F420 metabolism. Here we report the over-expression of all of these proteins in M. smegmatis and testing of their importance for F420 production. The results indicate that co–expression of the F420 biosynthetic proteins can give rise to a much higher F420 production level. This was achieved by designing and preparing a new T7 promoter–based co-expression shuttle vector. A combination of co–expression of the F420 biosynthetic proteins and fine-tuning of the culture media has enabled us to achieve F420 production levels of up to 10 times higher compared with the wild type M. smegmatis strain. The high levels of the F420 produced in this study provide a suitable source of this cofactor for studies of F420-dependent proteins from other microorganisms and for possible biotechnological applications.

/pdf/metabolic-engineering-of-cofactor-f420-production-in-w633rhz3g4.pdf

Metabolic Engineering of Cofactor F420 Production in Mycobacterium smegmatis

Moths recognize a wide range of volatile compounds, which they use to locate mates, food sources, and oviposition sites. These compounds are recognized by odorant receptors (OR) located within the dendritic membrane of sensory neurons that extend into the lymph of sensilla, covering the surface of insect antennae. We have identified 3 genes encoding ORs from the tortricid moth, Epiphyas postvittana, a pest of horticulture. Like Drosophila melanogaster ORs, they contain 7 transmembrane helices with an intracellular N-terminus, an orientation in the plasma membrane opposite to that of classical GPCRs. EpOR2 is orthologous to the coreceptor Or83b from D. melanogaster. EpOR1 and EpOR3 both recognize a range of terpenoids and benzoates produced by plants. Of the compounds tested, EpOR1 shows the best sensitivity to methyl salicylate [EC50 = 1.8 · 10 12 M], a common constituent of floral scents and an important signaling compound produced by plants when under attack from insects and pathogens. EpOR3 best recognizes the monoterpene citral to low concentrations [EC50 = 1.1 · 10 13 M]. Citral produces the largest amplitude electrophysiological responses in E. postvittana antennae and elicits repellent activity against ovipositing female moths. Orthologues of EpOR3 were found across 6 families within the Lepidoptera, suggesting that the ability to recognize citral may underpin an important behavior.

David R. Greenwood

Papers

Phenolic compounds and methylglyoxal in some New Zealand manuka and kanuka honeys.

An alcohol acyl transferase from apple (cv. Royal Gala), MpAAT1, produces esters involved in apple fruit flavor

Metabolic Engineering of Cofactor F420 Production in Mycobacterium smegmatis

Odorant receptors from the light brown apple moth (Epiphyas postvittana) recognize important volatile compounds produced by plants.

Technology for high-throughput screens: the present and future using zebrafish.