Dynamic fluorescence polarization studies on lipid mobilities in phospholipid vesicles in the presence of calcium mediators

The influence of Ca²⁺ mediators (nifedipine, verapamil and prostaglandin F_2α) on fluorescence polarization of l-anilino-8-napthalene-sulphonate in dipalmitoyl phosphatidylcholine and dimyristoyl phosphatidylcholine liposomes was studied at various temperatures to understand the dynamic behaviour of membrane lipids. We also studied the effect of change in calcium concentration on the fluorescence polarization of the dye in the liposomes. Our results show increase in polarization (indicative of stiffening of the membrane) in the presence of Ca²⁺ ions. In the case of dimyristoyl phosphatidylcholine liposomes, all 3 drugs caused decrease in fluorescence polarization (increase in fluidity of the membrane) with or without Ca²⁺ ions in the medium. Contrary to this, in the case of dipalmitoyl phosphatidylcholine liposomes, the fluidization effect is observed for all the 3 drugs in the absence of Ca²⁺ ions; in the presence of Ca²⁺ ions stiffening is observed upon addition of nifedipine and verapamil which are antagonists, and fluidization is observed upon addition of prostaglandin F_2α. The role of drug-induced fluidity changes in membranes in therapy planning is discussed in the paper.     

Dissolved organic carbon fluctuations in Dal Lake waters

Dissolved organic carbon (DOC) fluctuations were studied in the surface water of Dal Lake from May 1984 to April 1985, at monthly intervals. Concentration of DOC varied from 0.140 mg l^–1 to 0.725 mg l^–1. A minimum was recorded in May and September, while an increase was observed during December and January. The fluctuations during the observation period showed a relationship with temperature and pH.     

The mylohyoid bridge in four population samples from India, with observations on its suitability as a genetic marker

Four adult skeletal samples from the states of Uttar Pradesh, Andhra Pradesh, and Bihar in India have been studied for the incidence of mylohyoid bridge. The incidence, varying between 2.98% and 7.14%, has been compared with frequencies reported for other populations of the world. The range of variation for Indians, as a whole, falls within the lower levels of the spectrum of worldwide variation for this trait, ranging between 0.47% for French Europeans and 33.8% observed among Plains American Indians. While noting its possible significance for clinical purposes, the suitability of the mylohyoid bridge as a population genetic marker has been discussed. It is emphasized that its use as a genetic marker in isolation of other discrete traits has serious limitations. For meaningful population definition and relationships as many discrete variants as possible ought to be utilized.     

Endogenous 24-hour cycle of core temperature and oxygen consumption in week-old Zucker rat pups

Summary Experiments were designed to test whether or not the 24-h core temperature fluctuations in week-old rat pups are of endogenous origin. Lean (Fa/-) Zucker rat pups born on the same day to mothers maintained in two different colonies with light/dark cycles 12 h out of phase with each other were mother-reared through the first 3–4 days of life and then artificially reared simultaneously in constant dim light. Continuous, automatic measurement of core temperature and oxygen consumption during artificial rearing showed clear 24-h rhythms in 5- to 8-day-old pups. Each rhythm reached a daily minimum at a time corresponding to the beginning of the light period in the colony of origin. The amplitude of these rhythms did not diminish during artificial rearing, nor did the phase difference between the rhythms of pups originating in the two colonies systematically change. The persistent 12-h phase differences between these two groups of pups prove that the observed rhythms are not caused by exogenous stimuli. We conclude that the rat pup possesses an endogenous time-keeping mechanism that permits the expression of overt rhythmicity at the age of 1 week.Abbreviations Tc core temperature - LD-pups born to a mother entrained to a 7:00 to 19:00 light cycle, then artificially reared in constant dim light - DL-pups born to a mother entrained to a 19:00 to 7:00 light cycle, then artificially reared in constant dim light - SCN suprachiasmatic nucleus     

ADAPTIVE LEAF ARCHITECTURE IN EMERGENT AND FLOATING SPARGANIUM

The robust emergent leaves of Sparganium eurycarpum and S. americanum are supported by corner fiber masses and large bundle sheaths, but the thin floating leaves of S. fluctuans and S. minimum have only moderate bundle sheaths. In emergent types heavily photosynthetic diaphragms bearing vascular bundles are separated from each other in the leaf compartments by three lightly photosynthetic diaphragms without bundles, but in floating types only every other heavily photosynthetic diaphragm has a bundle. Palisade chlorenchyma occurs only at aerial surfaces—abaxial and adaxial in emergent leaves, but only adaxial in floating leaves. Extra photosynthetic areas are provided in emergent leaves by concentrations of chlorenchyma in limited areas on interior partitioning walls, while the remainder of the walls is translucent. Since only 25 % of the diaphragms are heavily photosynthetic, and the others essentially transparent because of their diffusely distributed chloroplasts and large intercellular spaces, a sieve effect exists which allows even the interior parts of thick emergent leaves to photosynthesize.     

Beneficial effects of L-methionine in choline deficient diets of Oryzaephilus mercator (Fauvel) (Coleoptera).

Choline is an indispensable vitamin for Oryzaephilus mercator as its ommission in the diet results in slow growth and poor survival. These deficiency symptoms can be overcome by adding L-methionine to the choline-deficient diet. L-methionine however can improve the efficiency of the diet only up to a certain concentration beyond which no beneficial effects are recorded.