Galactosyltransferase activities in subcellular fractions of two YC8 lymphoma cell variants: does a relationship exist between antigenic determinants and acceptor sites for galactose?

Experiments have been undertaken to correlate physiological changes, observed in two YC8 cells variants (P and L) and some of their immunological and enzymatic properties. These cell lines show different responses towards antilymphocyte and anti-Moloney sera. Subcellular fractionations have been made. The A fractions (d: 1.14/1.16) have the highest ouabain-inhibited Mg²⁺-stimulated (Na⁺-K⁺)-dependent ATPase and galactosyltransferase activities. Some properties of the latter enzyme have been studied: whereas optima pH and requirements for Mn²⁺ ions have been found to be the same for both cell line enzymes, on the contrary, different kinetic parameters have been shown with respect to sugar donor (UDP-galactose) on endogeneous or exogeneous (ovomucoid) acceptors. Apparent Km for UDP-galactose is 1.7 × 10⁻⁶ M (P-cells) and 3.3 × 10⁻⁶ M (L-cells), on endogeneous acceptors, and P-cell V max < L-cell V max; on ovomucoid it is 0.61 × 10⁻⁶ M, for both cell lines. These results suggest the presence on L-cells of more endogeneous acceptor sites, the higher affinity of P-cells for UDP-galactose being balanced by less endogeneous acceptor sites for galactose. When ovomucoid is added, galactose transfer on endogeneous acceptor sites of both cells is negligible. Apparent Km for ovomucoid is 8.6 × 10⁻⁵ M (P-cells) and 4.3 × 10⁻⁵ M (L-cells). These data support the above-mentioned hypothesis: L-cell enzymes would be more rapidly saturated than P-cell enzymes because of the higher number of endogeneous sites on L-cells.This supposed acquired character of L-cells as well as their immunological behaviour could explain the modified properties of L-cells as compared to P-cells.     

The importance of the lysophosphatidylcholine and choline moiety of bile phosphatidylcholine in lymphatic transport of fat

A luminal supply of biliary phosphatidylcholine is important in the translocation of absorbed fat into lymph and in the amount and composition of phosphatidylcholine concurrently synthesized. This study was undertaken to determine whether the effect was due to absorbed lysophosphatidylcholine, to a specific (1-palmitoyl) biliary lysophosphatidylcholine or to extra choline supplied by lysophosphatidylcholine. Rats with bile fistulae and thoracic duct lymph fistulae were given test meals of oleic acid and monoolein (molar ratio 2 : 1) infused duodenally for 8 h. Addition of choline chloride to the test meal increased lymphatic output of triglyceride and phospholipid but not to values found previously in rats with supplements of bile phosphatidylcholine or with bile ducts intact. Addition of dioleoyl phosphatidylcholine increased triglyceride and phospholipid output to values found in rats with intact bile ducts. Since dioleoyl phosphatidylcholine was as efficient as biliary phosphatidylcholine it was concluded that a luminal supply of 1-palmitoyl lysophosphatidylcholine was not essential. It seemed likely from the smaller effect of supplemented choline and from the fatty acid composition of lymph phosphatidylcholine that the essential requirement was a supply of absorbed lysophosphatidylcholine for rapid reacylation to phosphatidylcholine.     

Role de l'intensite lumineuse rouge (630–670 nm) dans le determinisme photoperiodique de la diapause nymphale de Pieris brassicae

In previous communications we have reported the role of red light on the determinism of the pupal diapause of Pieris brassicae (630 to 670 nm, wavelengths corresponding to the maximum of absorption of pterobilin, the blue bile pigment present in the integument and haemolymph).Red light suppresses the diapausing effect of the 9-hr/24-hr photophase of white light (identical energy in both and similar to the energy under natural conditions). The activity of red light in two experimental conditions: 9-hr white light followed by 15 hr of red lights of different intensities, and 9-hr red lights of different intensities followed by 15 hr darkness is examined. The photoperiodic determinism of pupal diapause is discussed.     

Transmission experiments with pike fry (Esox Indus L.) rhabdovirus

Experimental infection of fertilized pike eggs with 'red-disease' virus produced 100% mortality in the fry. This mortality was associated with a disease that had previously been described as hydrocephalus internus, indicating that 'red-disease' and hydrocephalus are different manifestations of the same disease. The name pike fry rhabdovirus disease (PFRD) is suggested for the disease complex, and the name pike fry rhabdovirus (PFR) for the causative agent. Exposure of PFR to a Wescodyne * solution containing 25 ppm of iodine resulted in an inactivation of at least 99–99% of viral activity within 30 sec. Experimental egg transmission of PFR could be interrupted by disinfecting the eggs in a Wescodyne solution, suggesting that the virus was located on the egg surface. Conclusive evidence of a naturally occurring vertical transmission in pike culture is still lacking because, using FHM cells as a detection system, PFR could not be found in spawners and their sexual products. The susceptibility of pike fry to PFR rapidly decreases at increasing age.     

Selective inhibition of prostaglandin biosynthesis by gold salts and phenylbutazone

Gold salts and phenylbutazone selectively inhibit the synthesis of PGF_2α and PGE₂ respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE₂ and PGF_2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.     

Hastifolins A–G,antifeedant neo-clerodane diterpenoids from Scutellaria hastifolia

From the aerial parts of Scutellaria hastifolia, family Lamiaceae (Labiatae), seven neo-clerodane diterpenoids (hastifolins A–G) were isolated. The products are similar to the known scuteparvin and are characterized by being trans-cinnamoyl derivatives. Structures and stereochemistry were determined by intensive NMR investigation. Six of the products form three pairs of epimers at C-13. Hastifolins A–C showed significant antifeedant activity.