University of Crete

About: University of Crete is a education organization based out in Rethymno, Greece. It is known for research contribution in the topics: Population & Galaxy. The organization has 8681 authors who have published 21684 publications receiving 709078 citations. The organization is also known as: Panepistimio Kritis.

Bridging the Gap between Plant and Mammalian Polyamine Catabolism: A Novel Peroxisomal Polyamine Oxidase Responsible for a Full Back-Conversion Pathway in Arabidopsis

Abstract: In contrast to animals, where polyamine (PA) catabolism efficiently converts spermine (Spm) to putrescine (Put), plants have been considered to possess a PA catabolic pathway producing 1,3-diaminopropane, Δ1-pyrroline, the corresponding aldehyde, and hydrogen peroxide but unable to back-convert Spm to Put. Arabidopsis (Arabidopsis thaliana) genome contains at least five putative PA oxidase (PAO) members with yet-unknown localization and physiological role(s). AtPAO1 was recently identified as an enzyme similar to the mammalian Spm oxidase, which converts Spm to spermidine (Spd). In this work, we have performed in silico analysis of the five Arabidopsis genes and have identified PAO3 (AtPAO3) as a nontypical PAO, in terms of homology, compared to other known PAOs. We have expressed the gene AtPAO3 and have purified a protein corresponding to it using the inducible heterologous expression system of Escherichia coli. AtPAO3 catalyzed the sequential conversion/oxidation of Spm to Spd, and of Spd to Put, thus exhibiting functional homology to the mammalian PAOs. The best substrate for this pathway was Spd, whereas the N1-acetyl-derivatives of Spm and Spd were oxidized less efficiently. On the other hand, no activity was detected when diamines (agmatine, cadaverine, and Put) were used as substrates. Moreover, although AtPAO3 does not exhibit significant similarity to the other known PAOs, it is efficiently inhibited by guazatine, a potent PAO inhibitor. AtPAO3 contains a peroxisomal targeting motif at the C terminus, and it targets green fluorescence protein to peroxisomes when fused at the N terminus but not at the C terminus. These results reveal that AtPAO3 is a peroxisomal protein and that the C terminus of the protein contains the sorting information. The overall data reinforce the view that plants and mammals possess a similar PA oxidation system, concerning both the subcellular localization and the mode of its action.

Mediterranean diet of Crete: foods and nutrient content.

Abstract: Objectives To describe the traditional diet of Crete and evaluate the nutrient composition of 3 types of diet common in Crete by means of chemical analyses of composite food samples. To compare results with dietary analyses from a nutrient database developed at the University of Crete, Greece. Design Three composite diet samples were obtained based on 7-day weighed food records representing the traditional Cretan Mediterranean diet (diet A), typical diet of present-day Greek adolescents (diet B), and fasting diet of the Eastern Orthodox church (diet C). Analyses were performed chemically and using a nutrient database. Results Chemical analyses provided a definitive measure, for the first time, of the nutrient composition of the complete Greek diet as it was in the early 1960s. In comparing chemical analyses with nutrient database analyses, differences greater than 15% of the analyzed value were found in all 3 diets for cholesterol and some vitamins. The differences between analyzed and calculated values in total fat and saturated fat content were less than 15% in all diets. Applications/conclusions The present study provides 2 practical examples of the Mediterranean diet, which although widely publicized has rarely been analyzed chemically. Diet A has been shown to be related to the lowest rates for coronary heart disease and cancer mortality compared with the diets of the other populations of the Seven Countries study. As such, it could be recommended for health promotion and prevention of disease. Diet C contains even lower amounts of saturated fatty acids and would be excellent for patients with hypercholesterolemia. The high antioxidants in diet C probably maintain very low levels of low-density lipoprotein cholesterol. Dietary analyses of the Greek diet could be based on an operational database such as ours if further chemical analyses are performed on specific foods. These would result in improved precision of the database and possible extension into national food composition tables and a national dietary database. J Am Diet Assoc. 2000;100:1487-1493 .

Polariton condensate transistor switch

Abstract: A polariton condensate transistor switch is realized through optical excitation of a microcavity ridge with two beams. The ballistically ejected polaritons from a condensate formed at the source are gated using the 20 times weaker second beam to switch on and off the flux of polaritons. In the absence of the gate beam the small built-in detuning creates a potential landscape in which ejected polaritons are channelled toward the end of the ridge where they condense. The low-loss photonlike propagation combined with strong nonlinearities associated with their excitonic component makes polariton-based transistors particularly attractive for the implementation of all-optical integrated circuits.

Minos as a genetic and genomic tool in Drosophila melanogaster

Abstract: Much of the information about the function of D. melanogaster genes has come from P-element mutagenesis. The major drawback of the P element, however, is its strong bias for insertion into some genes (hotspots) and against insertion into others (coldspots). Within genes, 5′-UTRs are preferential targets. For the successful completion of the Drosophila Genome Disruption Project, the use of transposon vectors other than P will be necessary. We examined here the suitability of the Minos element from Drosophila hydei as a tool for Drosophila genomics. Previous work has shown that Minos, a member of the Tc1/mariner family of transposable elements, is active in diverse organisms and cultured cells; it produces stable integrants in the germ line of several insect species, in the mouse, and in human cells. We generated and analyzed 96 Minos integrations into the Drosophila genome and devised an efficient “jump-starting” scheme for production of single insertions. The ratio of insertions into genes vs. intergenic DNA is consistent with a random distribution. Within genes, there is a statistically significant preference for insertion into introns rather than into exons. About 30% of all insertions were in introns and ∼55% of insertions were into or next to genes that have so far not been hit by the P element. The insertion sites exhibit, in contrast to other transposons, little sequence requirement beyond the TA dinucleotide insertion target. We further demonstrate that induced remobilization of Minos insertions can delete nearby sequences. Our results suggest that Minos is a useful tool complementing the P element for insertional mutagenesis and genomic analysis in Drosophila.