Structural regularities in tetraether lipids of Caldariella and their biosynthetic and phyletic implications

Individual di(biphytanyl) diglycerol tetraether lipids from thermoacidophile archaebacteria of the Caldariella series, with differently cyclized biphytanyl components, are separated and shown to have structures 8–12, with the glycerol and biphytanyl components demonstrably both antiparallel and with partial assignments of stereochemistry. Tetraethers with alternative arrangements of the components are absent. The structures allow previous observations on these and related lipids to be rationalized both biosynthetically and phyletically.     

Studies on the lipid metabolism of the metacercariae of Clinostomum complanatum (Trematoda: Digenea)

Metacercariae of Clinostomum complanatum possess considerable amounts of lipids. Fractionation of the lipids shows triglycerides and phospholipids as the major components whereas cholesterol and free fatty acids are minor components. Furthermore phospholipid fractions by thin layer chromatography reveal lecithin and cephalin as the major polar lipids whereas lysolecithin and lysocephalin are present in small fractions. The specific activity of lipase (E.C. 3.1.1.3) is 150.8 μg free fatty acids liberated/mg protein/h. Epinephrine, testosterone, insulin, sodium fluoride and iodoacetate stimulated, but 2-propanol inhibited, the lipase activity.     

Changes in carbohydrates and lipids during embryonic development ofAntheraea mylitta (Lepidoptera)

Changes in carbohydrate and lipid metabolism during embryonic development inAntheraea mylitta were studied. While carbohydrates were metabolized during early embryogenesis, lipids were catabolised at the later stages. A significant increase in both total carbohydrates and glycogen on days 5 and 6 suggested the concurrent occurrence of both gluconeogenesis and glycogenesis. As the development of the embryo proceeds, both lipids and carbohydrates were utilised, resulting in the increase in the concentration of citrate, pyruvate and lactate.     

Composition en lipides et acides gras de deux esèces de Taphrina parasites de Prunus domestica

Four strains of both Taphrina pruni and T. institiae were cultivated under identical conditions and and lipids and fatty acids were quantitatively analysed at two stages of their development. Tri- and diglycerides are the major neutral lipids in both species. Phosphatidylcholine and phosphatidylethanolamine are the most abundant polar lipids. Qualitatively, the two species show identical fatty acid contents, except for margaric acid (17:0) which was only found in Taphrine pruni. Quantitatively there are several differences: palmitoleic acid (16:1) occurs in reasonable amounts regularly and only in Taphrina pruni. The ratios 16:0/18:0 and 18:1/18:2 are generally higher for T. insititiae whereas the degree of unsaturation of fatty acids is higher in the former. The results are discussed with regard to data on other fungal species.     

The role of glucose in the lipid metabolism of the rat tapeworm Hymenolepis diminuta

The composition of the neutral lipids and the phospholipids, and the role of glucose in the lipid metabolism of prepatent (12-day-old) Hymenolepis diminuta has been studied in vitro. Triglyceride was the most abundant lipid present; substantial amounts of sterol and sterol ester, diglyceride, free fatty acids and monoglycerides were also present. The phospholipids, which were qualitatively and quantitatively similar to those of other invertebrates and vertebrates, were, in order of abundance, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphoinositide, lysophosphatidylcholine, cardiclipin, phosphatidic acid, lysophosphatidic acid and phosphatidylglycerol. Small amounts of glucose carbon were incorporated into the lipids, principally the water soluble (glycerol) moiety of the triglycerides; only traces were incorporated into the phospholipids. Small amounts of glucose were converted to inositol and galactose. The principal pathway of triglyceride synthesis is suggested to be via the α-glycerophosphate-phosphatidic acid-diglyceride pathway.     

Evidence for a credit-card-swipe mechanism in the human PC floppase ABCB4

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GROWTH AND ORGANIC OSMOLYTES OF GEOGRAPHICALLY DIFFERENT ISOLATES OF MICROCOLEUS CHTHONOPLASTES (CYANOBACTERIA) FROM BENTHIC MICROBIAL MATS:RESPONSE TO SALINITY CHANGE1

The comparative growth and osmotic acclimation often culture strains of the marine benthic cyanobacterium Microcoleus chthonoplastes Thuret isolated from microbial mats in Germany, Spain, Egypt, the United States, Mexico, Chile, and Australia were investigated in salinities ranging from freshwater to twice seawater. All isolates showed a broad growth versus salinity response consistent with the dominance of this species in intertidal and hypersaline microbial communities. Growth optima, salinity preferences, and maximum growth rates differed for each isolate and could be related to the habitat from which they were isolated. This is most obvious when comparing strains from brackish habitats with those from a hypersaline lake. While the former isolates exhibited sharply pronounced growth optima under hyposaline conditions, cultures from the hypersaline environment grew best in salinity more than double seawater. The major low-molecular weight organic compounds present in all M. chthonoplastes strains were the carbohydrates glycosylglycerol and trehalose. This was proven by using ¹³C-nuclear magnetic resonance spectroscopy. Glycosylglycerol was synthesized and accumulated with increasing salinities, indicating its role as an osmolyte. In contrast, trehalose was present in relatively high concentrations under hyposaline conditions only. Differences in the patterns of growth versus salinity, as well as in those of osmotic acclimation among the M. chthonoplastes isolates, point to the development of different physiological ecotypes within the species.