Mitsuyo Horikawa

Symbiotic bacterium modifies aphid body color.

Turncoat Aphids Aphid color has consequences for the fate of the wearer: Coccinellid beetles prefer to eat red ones and parasitoid wasps attack green ones. What might happen if aphids could change color and outwit their predators? Tsuchida et al. (p. 1102) have found that a subpopulation of the pea aphid can do this, but not without help from a previously unknown species of bacterium that lives intimately with the aphid as an endosymbiont and makes red aphids turn green. The bacterium interferes with host pigment biosynthesis—itself borrowed from fungi long ago in evolution—to stimulate blue-green pigment production as the aphid larva matures, turning the red nymph into a green adult. The ecological consequences of this about-turn of color have yet to be tested, but other studies have shown a variety of effects on aphid behavior mediated by endosymbionts in response to adaptation to different food plants, temperature tolerance, and predator avoidance. Infection with a symbiotic bacterium leads to a spectacular phenotypic change in its host, making red aphids turn green. Color variation within populations of the pea aphid influences relative susceptibility to predators and parasites. We have discovered that infection with a facultative endosymbiont of the genus Rickettsiella changes the insects’ body color from red to green in natural populations. Approximately 8% of pea aphids collected in Western Europe carried the Rickettsiella infection. The infection increased amounts of blue-green polycyclic quinones, whereas it had less of an effect on yellow-red carotenoid pigments. The effect of the endosymbiont on body color is expected to influence prey-predator interactions, as well as interactions with other endosymbionts.

Synthesis of uracil-5- and adenine-8-phosphonic acids

Abstract Successive treatments of 5-bromo-2,4-dimethyoxypyrimidine (I) with n-butyllithium and diethyl chlorophosphonate followed by dealkylation afforded uracil-5-phosphonic acid (V). Adenine-8-phosphonic acid (IX) was also prepared by a similar method, starting from 6-chloro-9-(tetrahdyro-2-pyranyl)purine (VI).

Viridaphin A1 Glucoside, a Green Pigment Possessing Cytotoxic and Antibacterial Activity from the Aphid Megoura crassicauda

A green pigment, viridaphin A₁ glucoside (1), was isolated from the green aphid Megoura crassicauda. One- and two-dimensional NMR spectrometric analyses of 1 and its aglycone established the structure as an octacyclic compound. Viridaphin A₁ glucoside exhibited cytotoxicity against HL-60 human tumor cells with an IC₅₀ of 23 μM and antibacterial activity against Bacillus subtilis NBRC 3134 with a minimum inhibitory concentration of 10.0 μg/mL. These results suggested that aphid pigments may protect aphids from invasive species, including viruses and bacteria.

Megouraphin Glucosides: Two Yellowish Pigments from the Aphid Megoura crassicauda

Two new yellow pigments, megouraphin glucosides A (1) and B (2), were isolated from the aphid Megoura crassicauda. Their structures were established by detailed analysis of their 1D and 2D NMR spectra and via chemical conversion. INTRODUCTION Aphids produce novel pigments, such as the protoaphins, 1-7 furanaphin, 8 and the uroleuconaphines, 9,10 viridaphin A1 glucoside, 11 which may possess interesting biological activities such as cytotoxicity. 8,9,11,12 The presence of pigments is also important for expressing aphid body color, and it is presumed that subtle differences body coloration (color polymorphism) affect predator-prey interactions. 13 Therefore, the unique structures and potentially important biological activities of aphid pigments are of interest. As the first step, we have been studying the chemical structures of pigments in aphids. 8-11 In the present manuscript, we describe our studies of the aphid Megoura crassicauda (Figure 1) 14 and the isolation of two fluorescent yellow pigments named megouraphin glucosides A (1) and B (2) (Figure 2). Their chemical structures are described in detail. Figure 1. Megoura crassicauda HETEROCYCLES, Vol. 85, No. 1, 2012 95

Isolation and Total Syntheses of Cytotoxic Cryptolactones A1, A2, B1, and B2: α,β-Unsaturated δ-Lactones from a Cryptomyzus sp. Aphid

The cryptolactones A1, A2, B1, and B2, which are α,β-unsaturated δ-lactones, were isolated from a Cryptomyzus sp. aphid. The structures were established by 1-D and 2-D NMR spectra and CI-HRMS. Their absolute configurations were determined with the Kusumi-Mosher method, combined with asymmetric total syntheses. The syntheses were accomplished with the Mukaiyama aldol reaction and olefin metathesis, which utilized the second-generation Grubbs catalyst for the key steps. These compounds exhibited cytotoxic activity against human promyelocytic leukemia HL-60 cells with IC50 values of 0.97-5.3 μM.

A role of uroleuconaphins, polyketide red pigments in aphid, as a chemopreventor in the host defense system against infection with entomopathogenic fungi

Four red polyketide pigments, uroleuconaphins A1 (1) and B1 (2) and their glucosides 3 and 4, were isolated from the red goldenrod aphid Uroleucon nigrotuberculatum. Although these red pigments exist only as glucosides 3 and 4 in the intact insect body, 3 and 4 convert instantly to aglycones 1 and 2 at death. Pigments 1 and 2 inhibited the growth of Lecanicillium sp. (Ascomycota: Cordycipitaceae) and 1, 2, and 3 were active against Conidiobolus obscurus (Entomophthoromycota; Entomophthorales); these fungal species are pathogenic. We therefore regard aphid pigments 1–4 as chemopreventive agents that aid in the resistance of infection by entomopathogenic fungi at the level of the individual aphid and/or at the species level.

CCDC 1529338: Experimental Crystal Structure Determination

Related Article: Hiroto Kaku, Minami Ito, Mitsuyo Horikawa, Tetsuto Tsunoda|2018|Tetrahedron|74|124|doi:10.1016/j.tet.2017.11.045