A novel lysophosphatidic acid acyltransferase enzyme (LPAAT4) with a possible role for incorporating docosahexaenoic acid into brain glycerophospholipids

AbstractGlycerophospholipids are important components of cellular membranes, required for constructing structural barriers, and for providing precursors of bioactive lipid mediators. Lysophosphatidic acid acyltransferases (LPAATs) are enzymes known to function in the de novo glycerophospholipid biosynthetic pathway (Kennedy pathway), using lysophosphatidic acid (LPA) and acyl-CoA to form phosphatidic acid (PA). Until now, three LPAATs (LPAAT1, 2, and 3) have been reported from the 1-acyl-glycerol-3-phosphate O-acyltransferase (AGPAT) family. In this study, we identified a fourth LPAAT enzyme, LPAAT4, previously known as an uncharacterized enzyme AGPAT4 (LPAATδ), from the AGPAT family. Although LPAAT4 was known to contain AGPAT motifs essential for acyltransferase activities, detailed biochemical properties were unknown. Here, we found that mouse LPAAT4 (mLPAAT4) possesses LPAAT activity with high acyl-CoA specificity for polyunsaturated fatty acyl-CoA, especially docosahexaenoyl-CoA (22:6-CoA, DHA-CoA). mLPAAT4 was distributed in many tissues, with relatively high expression in the brain, rich in docosahexaenoic acid (DHA, 22:6). mLPAAT4 siRNA in a neuronal cell line, Neuro 2A, caused a decrease in LPAAT activity with 22:6-CoA, suggesting that mLPAAT4 functions endogenously. siRNA in Neuro 2A cells caused a decrease in 18:0–22:6 PC, whereas mLPAAT4 overexpression in Chinese hamster ovary (CHO)-K1 cells caused an increase in this species. Although DHA is considered to have many important functions for the brain, the mechanism of its incorporation into glycerophospholipids is unknown. LPAAT4 might have a significant role for maintaining DHA in neural membranes. Identification of LPAAT4 will possibly contribute to understanding the regulation and the biological roles of DHA-containing glycerophospholipids in the brain

Difference in leaf herbivory between two plant-ant taxa associating with a myrmecophytic species, Macaranga lamellata

Macaranga lamellata (Euphorbiaceae) is a myrmecophytic species that is protected against herbivorous insects by two plant-ant taxa, Colobopsis macarangae (Formicinae) and Crematogaster spp. (Myrmicinae). Although a single M. lamellata tree houses one plant-ant colony of either of the two taxa, both coexist in a population of M. lamellata in a Bornean rainforest. To elucidate the extent of herbivory damage upon M. lamellata trees associated with Colobopsis relative to trees associated with Crematogaster, we counted the number of leaf galls and measured the leaf loss area chewed by leaf-chewing insects on M. lamellata in the forest. The occurrence of gall midges was not significantly different between the trees associated with the two plant-ants, while the degree of leaf-chewing herbivory was significantly higher on Crematogaster-associated trees than Colobopsis-associated trees. The data gathered on chewing traces observed on Crematogaster-associated trees indicated that most herbivory damage was caused by a phasmid species. These results suggest that the herbivory pressures and occurrences of different herbivore species differ between Crematogaster-associated and Colobopsis-associated trees within a population of M. lamellata

Synthesis of 11,12-leukotriene A4, 11S,12S-oxido-5Z,7E,9E,14Z-eicosatetraenoic acid, a novel leukotriene of the 12-lipoxy genase pathway

AbstractA simple and efficient method for preparing 11,12-leukotriene A4 has been established by the stereospecific biomimetic route from arachidonic acid. 12S-Hydroperoxy-5Z,8Z,10E,14Z-eicosatetraenoic acid was synthesized using a partially purified 12-lipoxygenase of porcine leukocytes. The methyl ester of the compound was then chemically converted to two labile epoxides with a conjugated triene structure. These compounds were identified by proton NMR and mass spectrometry to be 11S,12S-oxido-5Z,7E,9E,14Z-eicosatetraenoic acid (11,12-leukotriene A4) and its geometric isomer

Abukuma and Sanbagawa metamorphic belts in the Kanto district

'29th IGC field trip guide book' vol.5, C08: [Editors] Hirokazu Kato, Harufumi Noro「IGC巡検ガイドブック」 第5巻: [編者] 加藤 碵一, 野呂 春

Timing of butterfly parasitization of a plant-ant-scale symbiosis

In the Southeast Asian tropics, Arhopala lycaenid butterflies feed on Macaranga ant-plants inhabited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiversifying for the past 20-16 million years (Myr), and that (2) the tripartite symbiosis was formed 9-7 Myr ago, when the scale insects became involved in the plant-ant mutualism. To determine when the lycaenids first parasitized the Macaranga tripartite symbiosis, we constructed a molecular phylogeny of the lycaenids that feed on Macaranga by using mitochondrial and nuclear DNA sequence data and estimated their divergence times based on the cytochrome oxidase I molecular clock. The minimum age of the lycaenids was estimated by the time-calibrated phylogeny to be 2.05 Myr, about one-tenth the age of the plant-ant association, suggesting that the lycaenids are latecomers that associated themselves with the pre-existing symbiosis of plant, ant, and scale insects.ArticleECOLOGICAL RESEARCH. 27(2):437-443 (2012)journal articl

Kow-altitude forest of Japanese beech (Fagus crenata) in the northern Tajima District, Hyogo Prefecture, and its prerequisites

Beech forests characterized by Fagus crenata of F. japonica are distributed at abnormal low altitudes, down to 150 meters above sea level, in the northern Tajima district on the Japan Sea side, southwestern Japan. The abnormal low-altitudes are investigated to have been resulted from (1) marked lowering of the beech zone in snowy area, (2) large snow depths in the northern Tajima district and (3) escaping from severe human disturbance since the beginning of agriculture, particularly during the high economic growth period. The following two factors promote the lowering of the beech zone in snowy area: Creeping and avalanching of deep snow tend to destroy most small trees, but young beech can endure through crawling and triangulating their stem profiles. While large animals as hares and serows feed preferably winter buds and sprouts of deciduous trees, especially of beech, deep snow cover in the district protects from the browsing of animals. In addition, the large longevity of beech up to 400 years probably contributes to preserve the lowered distributions. Deep snow in the district is attributable to the large relief of the Hyonosen mountain mass behind. The mountain mass elevates the water-saturated winter wind that has traveled over the warm Japan Sea water from the cooled and dried Asian continent. Human activities destroyed most of natural forests in Japan, but small human population in the mountainous northern Tajima district reduced the destructive effects. The spot forests of beech are thus preserved as relicts of previous one extensive over the district. Many of them are left to protect villages from slope disasters. The spot forests seem to have potentials to grow over the snowy area, so that it is not impossible for us to revive them with suitable supports