University of Stirling

About: University of Stirling is a education organization based out in Stirling, Stirling, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 7722 authors who have published 20549 publications receiving 732940 citations. The organization is also known as: Stirling University.

The consequences of brood size for breeding blue tits. iii. measuring the cost of reproduction: survival, future fecundity, and differential dispersal.

Abstract: To determine how the cost of reproduction varies with brood size, a population of blue tits (Parus caeruleus) breeding in Wytham Wood, England, was manipulated over a three year period. Two hundred sixteen pairs were randomly assigned 3, 6, 9, 12, or 15 nestlings; nestlings were exchanged soon after hatching. Survival of adult females (as measured by the proportion recaptured in the following winter and/or spring) declined significantly with increasing brood size in two out of three years; there was significant year-to-year variation in the relationship of recapture rate to brood size. Mean female recapture rates (averaged over the three years) declined in a linear fashion (P < 0.01). There was no significant linear or curvilinear relationship between male-recapture rate and brood size in any of the three years nor was there a significant linear or curvilinear relationship for the data averaged over the three years. Nevertheless, recapture proportions for males differed significantly with respect to brood size (χ2 test, P < 0.05). The possibility that experimental brood size influences subsequent dispersal (and therefore biases measures of survival based on recapture rates to differing degrees) was examined by comparing distances moved by breeding adults from one year to the next. There was no relationship between brood size and dispersal distance within the study area for either sex, except that females given broods of three were significantly more likely to move more than 300 m than were those given broods of 6-15 young. Both males and females showed evidence of a cost with respect to future fecundity: as brood size increased, the number of surviving offspring produced in the following year decreased from 1.5-1.6 (for adults that had reared 3-6 young) to 0.4 (for those that had reared 15 young). The relationship of future reproductive success to experimental brood size did not differ among years or between the sexes. The number of eggs laid and number of young hatched in year n + 1 did not differ significantly with respect to brood size in year n; rather, differences in future fecundity reflected differences in the survival prospects of young reared in year n + 1.

Cloning and functional characterisation of polyunsaturated fatty acid elongases of marine and freshwater teleost fish.

Abstract: Enzymes that lengthen the carbon chain of polyunsaturated fatty acids are key to the biosynthesis of the highly unsaturated fatty acids, arachidonic, eicosapentaenoic and docosahexaenoic acids from linoleic and alpha-linolenic acids. A Mortierella alpina cDNA polyunsaturated fatty acid elongase sequence identified mammalian, amphibian, zebrafish and insect expressed sequence tags (ESTs) in GenBank. Consensus primers were designed in conserved motifs and used to isolate full length cDNA from livers of several fish species by Rapid Amplification of cDNA Ends (RACE). The amplified cDNAs encoded putative open reading frames (ORFs) of 288-294 amino acids that were highly conserved among the fish species. Heterologous expression in yeast, Saccharomyces cerevisiae, demonstrated that all of the ORFs encoded elongases with the ability to lengthen polyunsaturated fatty acid substrates with chain lengths from C18 to C22 and also monounsaturated fatty acids, but not saturated fatty acids. There were differences in the functional competence of the elongases from different fish species. Most of the fish elongases showed a pattern of activity towards different fatty acid substrates in the rank order C18>C20>C22, although the tilapia and turbot elongases had similar activity towards 18:4n-3 and 20:5n-3. The fish elongases generally showed greater activity or similar activities with n-3 than with n-6 homologues, with the exception of the cod enzyme which was more active towards n-6 fatty acids.

Lipids and fatty acids in ice algae and phytoplankton from the Marginal Ice Zone in the Barents Sea

Abstract: Samples of ice algae from the Marginal Ice Zone in the Barents Sea could be divided into two categories: one dominated by assemblages of Melosira arctica, and the other dominated by Nitzschia frigida and associated diatoms. Total lipid from the Melosira assemblages consisted of approximately equal amounts of polar lipids and triacylglycerols. Total lipid from the Nitzschia assemblages contained more triacylglycerols than polar lipids. Total lipid from the Melosira assemblages had higher percentages of C16 PUFA, especially 16:4(n-1) and 20:5(n-3), than that from the Nitzschia assemblages, this reflecting the higher percentages of both C16 PUFA and 20:5(n-3) in polar lipids than in triacylglycerols. Phytoplankton from the pelagic zone were␣richer in flagellates and contained less C16 PUFA and 20:5(n-3) but more C18 PUFA and 22:6(n-3). The dominance of diatoms in the ice-algae assemblages in the Marginal Ice Zone and their high nutritional value as a source of 20:5(n-3) for higher trophic levels are emphasised.