Clyde Ogg

Prostaglandin biosynthesis by fat body from the tobacco hornworm, Manduca sexta

We describe prostaglandin (PG) biosynthesis by microsomal-enriched preparations of fat body from larvae of the tobacco hornworm Manduca sexta. Four major PGs were synthesized under most experimental conditions, PGA2, PGE2, PGD2 and PGF2 alpha. PGA2, was the predominant product under most conditions. Unlike mammals, in which PGA2, is generally thought to arise from non-enzymatic rearrangements of PGE2, the fat body preparations did not convert exogenous PGE2 into PGA2. These findings suggest that PGA2 is an important fat body product that is synthesized by a route that does not involve PGE2. The PG synthase activity and the overall profile of PG synthesis were sensitive to experimental conditions, including incubation time, temperature, and protein concentration. Optimal PG biosynthesis was observed with 1 mg of microsomal-rich protein, incubated at 30 degrees C for 1-2 min. The fat body preparations is sensitive to two non-steroidal anti-inflammatory drugs, indomethacin and naproxen, both of which inhibited PG synthesis at low dosages.

Arachidonic acid and prostaglandin E2 in malpighian tubules of female yellow fever mosquitoes

The fatty acid compositions of Malpighian tubules from adult females of the mosquito Aedes aegypti were determined for total lipids, phospholipids, triacylglycerols and three phospholipid fractions, namely phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol/phosphatidylserine (PI/PS). The prostaglandin precursor arachidonic acid (20:4n-6) occurred in total lipids and phospholipids, but not triacylglycerols. Within phospholipids, nearly all of the 20:4n-6 was detected in PC, with only traces in PE, and none was detected in PI/PS. Isolated Malpighian tubules incorporated exogenous radioactive 20:4n-6 into tissue phospholipids and diacylglycerols, with most of the radioactivity recovered in diacylglycerol. These data indicate selective incorporation of 20:4n-6 into tissue lipids. PGE2 was detected in Malpighian tubule whole mounts by immunohistochemical staining. These findings support the idea that prostaglandins are physiologically active in mosquito Malpighian tubules.

Fatty acid composition and incorporation of arachidonic acid into phospholipids of hemocytes from the tobacco hornworm Manduca sexta

Abstract The fatty acid compositions were determined for total lipids, triacylglycerols, phospholipids and four phospholipid fractions, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine/phosphatidylinositol (PS/PI) and cardiolipin (CA) obtained from hemocytes and cell-free serum from second day, fifth instar larvae of the tobacco hornworm Manduca sexta and the standard Manduca rearing medium. The hemocyte fatty acid profiles were considerably different from the profiles of the medium the insects were reared on and from the profiles of the cell-free serum. Hemocyte neutral lipids had lower proportions of polyunsaturated fatty acids than phospholipids. The fatty acid profiles of PC, PE, PS/PI and CA differ from each other and from the total lipid profiles, indicating selective fatty acid incorporation into hemocyte phospholipid species. Studies with radioactive arachidonic acid similarly indicated selective incorporation of polyunsaturated fatty acids into hemocyte lipids. Under our in vitro conditions, >40% of the total radioactivity was incorporated into hemocyte lipids. About 93% of the incorporated radioactivity was found in phospholipids. Within phospholipids. most of the radioactivity was associated with PC (46%), and less with PE (28%) and PS/PI (21%). Very little radioactivity was recovered in CA (0.9%).

Phospholipid and triacylglycerol fatty acid compositions of the major life stages and selected tissues of the tobacco hornworn Manduca sexta

Abstract 1. 1. The fatty acid compositions of whole animals from all life stages and of selected tissues from larvae and adults of the tobacco hornworm Manduca sexta were analyzed. 2. 2. The major components were the C16 and C18 saturated and unsaturated fatty acids that are expected in insect tissue lipids. 3. 3. Eicosanoid-precursors polyunsaturated fatty acids, including 20:3 n-6, 20:4 n-6 and 20:5 n-3, were detected in most tissues. 4. 4. The fatty acid profiles among the life stages we examined, specifically, eggs, larvae, wandering larvae, prepupae, pupae and adults. 5. 5. The fatty acid profiles different among the various tissues were examined, suggesting that individual tissues arranged their own fatty acid compositions. The fatty acid profiles of analogous tissues from larvae and adults also differed from each other.

Seasonal changes in lipid composition during the reproductive cycle of the red-chinned lizard, Sceloporus undulatus erythrocheilus

Abstract 1. 1. Fatty-acid analyses of triacylglycerol from lizard fat bodies, ovarian eggs, oviductal eggs and liver through the reproductive cycle were performed by gas chromatography. 2. 2. Triacylglycerol comprised 88% of total lipids in fat bodies early in the reproductive season and declined to 66% following egg production. 3. 3. Predominant fatty acids in fat bodies, liver and ovarian eggs were myristic (14:0), palmitic (16:0), oleic (18:0) and linoleic ( 18:2n-6 ) acids. 4. 4. Oviductal eggs had little myristic but had an additional predominate type, linolenic ( 18:3n-3 ).

Polyunsaturated fatty acid metabolism inferred from fatty acid compositions of the diets and tissues of the gypsy moth lymant ria dispar

Abstract 1. 1. Phospholipid fatty acid compositions of whole animals from all life stages of the gypsy moth Lymantria dispar and the fatty acid compositions of total lipids of their larval culture medium were determined. 2. 2. The major components of the larval diet and the insect tissues were the C16 and C18 saturated and unsaturated fatty acids that are expected in plant and insect lipids. 3. 3. The fatty acid profiles of the insects and of their larval diet were different. 4. 4. There were small differences in fatty acid profiles of phospholipids and triacylglycerols from different life stages of the gypsy moths, and substantial differences between phospholipids and triacylglycerols within life stages. 5. 5. Certain C18 and C20 polyunsaturated fatty acids (PUFAs) that were not present in the diets were detected in the insect tissue phospholipids. 6. 6. Biosynthesis of certain PUFAs from 18:2n-6 and from 18:3n-3 is inferred from these observations.