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Functions of carotenoids: diversity and evolution
s113
P23-4
P23-6
Lipids of the eggs and neonates of oviparous and viviparous lizards Sueake BK and Thompson MB Department of Biochemistry and Nutrition, Scottish Agricultural College, Ayr, KA6 5HW, UK School of Biological Sciences, Zoology Building, University of Sydney, NSW 2006, Australia
Prostaglandin Fh Receptors in the Brushtail Possum, Trichosurus vulpecula and the Short-Nosed Bandicoot, Zsoodon tnacrourus at Birth, Veitch CE, Sernia C* and Gernmell RT Departments of Anatomical Sciences and Physiology and Pharmacology*, University of Queensland, St Lucia, Brisbane, Queensland, Australia 4072
The aims of this study were: firstly, to determine whether the reduction in relative egg size with increasing placentotrophy is accompanied by the selective loss or reduction in any of the yolk lipid components; secondly, in viviparous species, to estimate the relative contributions of the yolk versus the placenta in supplying lipid to the fetus. The egg lipids of the three species of oviparous and one lizard consisted of species of type I viviparous approximately 85% triglyceride (TG), 11% phospholipid (PL), 2% cholesteryl ester (CE) and 1% cholesterol (Ch). By contrast, those of the two type I1 and two type III viviparous species studied contained about 69% TG, 20% PL, 5% CE and 5% Ch. Thus increasing placentotrophy has promoted a reduction in the level of the high-energy TG in the egg with greater proportions of the lower energy PL, CE and Ch. The neonates of the type III viviparous lizard Pseudemoia spenceri contained 1.2 times more lipid than the initial egg. Since lipid is used extensively for energy by the fetus, this indicates substantial lipid transfer across the placenta.
Prostaglandin Fzc, (PGF2,J is involved with the regression of the corpus luteum (CL). Regression occurs at parturition in the possum but later in the bandicoot. The plasma concentration of 13, 14-dihydro-15-keto-prostaglandin Fla (PGFM), the major metabolite of PGFza, is briefly elevated at birth in the possum and elevated for several days around birth in the bandicoot. In both species, PGFz, injection induces adoption of the birth position. This study investigates PGFza receptors in the uterus and CL of possums and bandicoots at parturition. PGF2, receptors are not present in the bandicoot and possum uteri and the bandicoot CL. PGFzc, does not appear to be involved with uterine contractions in the possum or the bandicoot at parturition. However, low concentrations of receptors were found in possum CL, suggesting the involvement of PGFzu in CL regression. In the bandicoot there were no PGF2, receptors in the CL at birth. This provides an explanation for the failure of PGFzu administration to regress the bandicoot CL at birth. However, PGF2, injections will cause regression of the CL at day 30 of lactation. P24-1
P23-5
Functions of carotenoids: diversity and evolution Comparison of nutrient transport across the placenta of lizards differing in placental complexity.
Vershinin A. IORAS, N.Maslovka 18-84, 103220 Moscow, Russia
Thompson MB School of Biological Sciences, University of Sydney, NSW 2006, Australia.
Carotenoids first emerged in procaryotes as lipids reinforcing cell membranes. Their long molecules have extremely rigid backbone of usually 10 to 11 conjugated C=C bonds - the length corresponding the thickness of hydrophobic zone of membrane they penetrate. Carotenoids retain their membrane-reinforcing function in some fungi and animals. The general structure of carotenoid molecule, originally having evolved for mechanical functions in membranes, possess a number of properties that proved to lit some new functions to perfection: Polyene chain of 9-11 double bonds absorbs light precisely in the gap of chlorophyll absorption light-harvesting function in all plants; Polyene of 9 conjugated bonds is the minimal one for quenching singlet oxygen and effective elimination of radical species - antioxidant function in many organisms. Carotenoids also are responsible for species-specific coloration, screening from excessive light and spectral filtering, defense of egg proteins from proteases in some invertebrates; retinal is a visual pigment in all animals and a chromophor in bacteriorhodopsm photosynthesis, retinoic acid in animals and abscisic acid in plants serve as hormones. All these functions utilize properties (mechanic. electronic, stereospecific) of a single structure - linear polyene chain evolved in bacteria for a single membrane-reinforcing function, thus demonstrating example of pure preadaptation.
The lizard family Scincidae exhibits a greater range of placental complexity than any other taxon of amniotes. Species which exhibit each of the four categories of complexity of the chorioallantoic placenta recognised in reptiles occur within this family, and three of the categories are represented in south-eastern Australia. I measured ionic, protein, lipid and energy contents of freshly ovulated eggs and neonates of species which exhibited placentae of the two intermediate categories to obtain an estimate of the net flux of nutrients across the placenta during pregnancy. Whereas there is a correlation between the quantity of placentotrophic provision of nutrients to the embryo and placental complexity, there are only minor differences in the compositions of yolks of freshly ovulated eggs among species with different placentae. Energy densities reflect the lipid and protein composition of the egg yolks and are not significantly different from oviparous species. Uptake of calcium and sodium by the embryo from the eggshell by oviparous species and across the placenta by viviparous species is augmented by uptake of potassium in placental species. There appears to be no net uptake of magnesium in any species
P23-4
P23-6
Lipids of the eggs and neonates of oviparous and viviparous lizards Sueake BK and Thompson MB Department of Biochemistry and Nutrition, Scottish Agricultural College, Ayr, KA6 5HW, UK School of Biological Sciences, Zoology Building, University of Sydney, NSW 2006, Australia
Prostaglandin Fh Receptors in the Brushtail Possum, Trichosurus vulpecula and the Short-Nosed Bandicoot, Zsoodon tnacrourus at Birth, Veitch CE, Sernia C* and Gernmell RT Departments of Anatomical Sciences and Physiology and Pharmacology*, University of Queensland, St Lucia, Brisbane, Queensland, Australia 4072
The aims of this study were: firstly, to determine whether the reduction in relative egg size with increasing placentotrophy is accompanied by the selective loss or reduction in any of the yolk lipid components; secondly, in viviparous species, to estimate the relative contributions of the yolk versus the placenta in supplying lipid to the fetus. The egg lipids of the three species of oviparous and one lizard consisted of species of type I viviparous approximately 85% triglyceride (TG), 11% phospholipid (PL), 2% cholesteryl ester (CE) and 1% cholesterol (Ch). By contrast, those of the two type I1 and two type III viviparous species studied contained about 69% TG, 20% PL, 5% CE and 5% Ch. Thus increasing placentotrophy has promoted a reduction in the level of the high-energy TG in the egg with greater proportions of the lower energy PL, CE and Ch. The neonates of the type III viviparous lizard Pseudemoia spenceri contained 1.2 times more lipid than the initial egg. Since lipid is used extensively for energy by the fetus, this indicates substantial lipid transfer across the placenta.
Prostaglandin Fzc, (PGF2,J is involved with the regression of the corpus luteum (CL). Regression occurs at parturition in the possum but later in the bandicoot. The plasma concentration of 13, 14-dihydro-15-keto-prostaglandin Fla (PGFM), the major metabolite of PGFza, is briefly elevated at birth in the possum and elevated for several days around birth in the bandicoot. In both species, PGFz, injection induces adoption of the birth position. This study investigates PGFza receptors in the uterus and CL of possums and bandicoots at parturition. PGF2, receptors are not present in the bandicoot and possum uteri and the bandicoot CL. PGFzc, does not appear to be involved with uterine contractions in the possum or the bandicoot at parturition. However, low concentrations of receptors were found in possum CL, suggesting the involvement of PGFzu in CL regression. In the bandicoot there were no PGF2, receptors in the CL at birth. This provides an explanation for the failure of PGFzu administration to regress the bandicoot CL at birth. However, PGF2, injections will cause regression of the CL at day 30 of lactation. P24-1
P23-5
Functions of carotenoids: diversity and evolution Comparison of nutrient transport across the placenta of lizards differing in placental complexity.
Vershinin A. IORAS, N.Maslovka 18-84, 103220 Moscow, Russia
Thompson MB School of Biological Sciences, University of Sydney, NSW 2006, Australia.
Carotenoids first emerged in procaryotes as lipids reinforcing cell membranes. Their long molecules have extremely rigid backbone of usually 10 to 11 conjugated C=C bonds - the length corresponding the thickness of hydrophobic zone of membrane they penetrate. Carotenoids retain their membrane-reinforcing function in some fungi and animals. The general structure of carotenoid molecule, originally having evolved for mechanical functions in membranes, possess a number of properties that proved to lit some new functions to perfection: Polyene chain of 9-11 double bonds absorbs light precisely in the gap of chlorophyll absorption light-harvesting function in all plants; Polyene of 9 conjugated bonds is the minimal one for quenching singlet oxygen and effective elimination of radical species - antioxidant function in many organisms. Carotenoids also are responsible for species-specific coloration, screening from excessive light and spectral filtering, defense of egg proteins from proteases in some invertebrates; retinal is a visual pigment in all animals and a chromophor in bacteriorhodopsm photosynthesis, retinoic acid in animals and abscisic acid in plants serve as hormones. All these functions utilize properties (mechanic. electronic, stereospecific) of a single structure - linear polyene chain evolved in bacteria for a single membrane-reinforcing function, thus demonstrating example of pure preadaptation.
The lizard family Scincidae exhibits a greater range of placental complexity than any other taxon of amniotes. Species which exhibit each of the four categories of complexity of the chorioallantoic placenta recognised in reptiles occur within this family, and three of the categories are represented in south-eastern Australia. I measured ionic, protein, lipid and energy contents of freshly ovulated eggs and neonates of species which exhibited placentae of the two intermediate categories to obtain an estimate of the net flux of nutrients across the placenta during pregnancy. Whereas there is a correlation between the quantity of placentotrophic provision of nutrients to the embryo and placental complexity, there are only minor differences in the compositions of yolks of freshly ovulated eggs among species with different placentae. Energy densities reflect the lipid and protein composition of the egg yolks and are not significantly different from oviparous species. Uptake of calcium and sodium by the embryo from the eggshell by oviparous species and across the placenta by viviparous species is augmented by uptake of potassium in placental species. There appears to be no net uptake of magnesium in any species