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In this work, combined efforts by Greek and Turkish scientists produced an updated validated NIS inventory of the Aegean ecoregion, covering 120 years of records up to August 2024. Of the 342 NIS currently present in the Aegean Sea, the majority (281 species) have invaded the South Aegean, followed by the North Aegean (128 species out of 206 NIS). A total of 73 species were added to the list, while 56 were removed. Overall, unaided spread of Lessepsian immigrants from the Levantine Sea and shipping are equally responsible for NIS reported at the regional level. An increase in publications addressing NIS matches the upward trend of NIS since the mid-1990s, which continues to the present day. While unaided introductions of Lessepsian species and/or direct introductions via the Suez Canal peaked in the South Aegean during 2000–2005, they peaked in 2012–2017 in the North Aegean—a decade later. The opposite pattern was observed in ship-transferred NIS. The spatial distribution of introduction hotspots largely reflects the following phenomena/processes: unaided introduction is witnessed initially in the southeastern Aegean Sea; monitoring efforts are concentrated in vulnerable and at-risk areas; and research efforts relate to the spatial allocation of institutions and marine experts working on marine NIS along the Aegean coasts. [ABSTRACT FROM AUTHOR]

This study contributes to filling knowledge gaps regarding recent information on the diet of the European hake, Merluccius merluccius Linnaeus, 1758, in the Greek seas, particularly its ontogenetic shifts and its spatiotemporal variability. The trophic preferences of M. merluccius were investigated in the North Aegean Sea during the summers of 2019 to 2023 with visual stomach content analysis to assess its composition, diversity, and variability across body-size classes, years, and subareas. The identified prey are functionally diverse and in many cases also primary targets for local fisheries. The ontogenetic trophic niche of hake was characterized by two distinct shifts, delineated by 10 and 50 cm body-size thresholds. Cephalopods were a prevalent dietary component for large hake individuals. The intermediate body-size classes demonstrated greater trophic niche breadth concerning prey diversity and absolute prey-size ranges. A feeding strategy characterized by the specialization of individuals was also revealed. The effect of the temporal and spatial context on the hake diet was occasionally correlated with spatiotemporal variations in the sizes of their populations. In conclusion, ontogenetic and spatiotemporal variability in the hake diet were found to be significant and should be considered in the data collection design and analyses of the trophic interactions of the species. [ABSTRACT FROM AUTHOR]

The diet of the lionfish (Pterois miles), an invasive species in the Aegean Sea, was examined by collecting stomach content data from fish collected in three study sites in the Aegean Sea (southern Crete, Kastellorizo, and Nysiros islands). Prey composition in terms of numerical abundance and frequency of occurrence was used to compare lionfish's diet between these sites. Lionfish largely preyed upon teleosts (4% to 83% numerical abundance and 16% to 58% frequency of occurrence, depending on the site) and decapods (12% to 95% numerical abundance and 11% to 81% frequency of occurrence). The most important teleost families in lionfish's diet were Gobiidae, Labridae, and Scorpaenidae, while decapods and especially the family Scyllaridae and the genus Plesionika were the dominant decapod prey items. The lionfish was found to be an especially successful generalist across the study sites, an opportunistic, predatory species overall, and at the same time, at a local level, it seems to be an equally successful specialist that could increase the predation mortality of already stressed prey populations and can be a serious threat to endemic, critically endangered, and/or commercially important species. [ABSTRACT FROM AUTHOR]

Pig skeletal muscle glycogen phosphorylase b was purified using ammonium sulfate fractionation, DEAE-Sephadex A-50 and Sephadex G-200 column chromatography. The purified enzyme was used to immunize rabbits in the presence or in the absence of complete Freund adjuvant. Antibodies against pig phosphorylase in pure form were isolated from rabbit antisera using insoluble immunoadsorbents of pig phosphorylase. Autoantibodies against the rabbit enzyme were obtained from the same antisera using insoluble immunoadsorbents of rabbit phosphorylase. Complete inactivation of pig phosphorylase was accomplished by an antibody/enzyme molar ratio equal to 4 and autoantibody/enzyme molar ratio equal to 130. Complete inactivation of rabbit phosphorylase was accomplished by an antibody enzyme molar ratio equal to 250 and autoantibody/enzyme molar ratio equal to 160. Passive haemagglutination technique gave positive results with minimum amounts of 0.02 µg·ml and 0.8 µg/ml for pig and rabbit phosphorylase respectively. Kinetic experiments have shown that antibodies and autoantibodies act as noncompetitive inhibitors of both enzymes with respect to AMP and glucose 1-phosphate but exhibit a mixed type of inhibition with respect to glycogen. When glycogen hydrolysates were used as substrate in place of intact glycogen molecules a pronounced decrease in the inhibitory capacity of antienzyme on the enzyme was demonstrated. [ABSTRACT FROM AUTHOR]

Sodium cholate at millimolar concentration is able to induce activity in rabbit muscle phosphorylase b in the absence of AMP. The maximum activation of the enzyme in presence of 7 mM sodium cholate was 24% of that achieved by 1 mM AMP. Other bile salts tested showed a negligible activating effect. The Ka for AMP was lowered fivefold by 5 mM of the steroid detergent, while the cooperative binding of the nucleotide was abolished Phosphorylase b', a modified form of phosphorylase in which the phosphorylation site has been removed by limited tryptic attack. presented an activation profile similar to that of phosphorylase b. In contrast. phosphorylase a was inhibited by the bile salt, while the activity of liver phosphorylase b, was not significantly affected. Modification of the AMP site of the enzyme with 2,3-butanedione could not inhibit sodium-cholate-induced activity, tert-Butanol, an organic solvent activator of phosphorylase b was found to enhance the activity induced by sodium cholate. The interaction of sodium cholate and phosphorylase b was also followed by difference spectroscopy using a fluorescein isothiocyanate - phosphorylase b conjugate. Furthermore, measurements of electron spin resonance demonstrated that the mobility of a spin-label bound at buried - NH2 groups of phosphorylase b decreases cooperatively with increasing bile salt concentration. [ABSTRACT FROM AUTHOR]

Rabbit skeletal muscle glycogen phosphorylase b was covalently bound to oyster glycogen by means of cyanogen bromide. Removal of the unbound enzyme was achieved, using DEAESephadex A-50 chromatography. Glycogen-bound phosphorylase b showed a higher affinity toward glucose 1-phosphate but a lower homotropic cooperativity, with respect to AMP activation, than the native enzyme. However, at low AMP concentrations conjugated phosphorylase b was as efficient as the free enzyme. It is of interest that glycogen-bound phosphorylase b exhibited catalytic activity upon its polysaccharide carrier. Kinetics of heat and cold inactivation indicated that the bound enzyme was considerably more resistant toward heat inactivation but less stable upon exposure to cold. It was shown also that both conjugated and native enzymes had identical pH optima, similar activity/temperature dependencies and the same resistance against trypsin inactivation. [ABSTRACT FROM AUTHOR]

It has been found that fluorescein dimercuric acetate acts as a potential inhibitor of transaminase. Although the holoenzyme was inhibited also by fluorescein isothiocyanate the latter fluorochrome was found to be a rather specific inhibitor of the apoenzyme. The interactions involved are fast, the induced effect reaching its maximum value in less than 1 min. The isolated fluorescein dimercuric acetate or fluorescein isothiocyanate and transaminase or apotransaminase complexes suggest that the fluorochromes reacts specifically with two active sulfhydryl or amino groups of the enzyme, respectively. The fluorescence intensity of the fluorochromes is substantially quenched during their interaction with transaminase and apotransaminase. A red shift in the absorption spectrum maximum from 498 nm to 512 nm was also observed when fluorescein dimercurie acetate solutions were titrated with transaminase or apotransaminase. The recorded shift for fluorescein isothiocyanate in the fluorescein-isothiocyanate · apotransaminase complex was from 493 nm to 502 nm, respectively. In contrast to the previous spectral changes a blue shift in the spectrum maximum from 498 nm to 478 nm was recorded during the stoichiometric interaction of fluorescein dimercurie acetate with cysteine. Comparative studies concerning the reactivity of fluorescein dimercuric acetate or fluorescein isothiocyanate with transaminase, apotransaminase and cysteine or lysine suggest that the alterations observed in the spectral and fluorescence properties of the fluorochromes during their interaction with transaminase and apotransaminase arose from their complexation with specific sulfhydryl groups of the enzyme. These groups should be located in a critical hydrophobic area of the transaminase molecule since their interaction abolishes the catalytic activity of the enzyme and alters the spectral and fluorescence properties of the fluorochromes in the same way as low polarity solvents. These sulfhydryl and amino groups might also play a functional role since they interact faster with fluorescein dimercuric acetate and fluorescein isothlocyanate than the sulfhydryl group of cysteine or the amino group of lysine. Quantitative parameters of the data obtained by conventional techniques and stopped-flow spectroscopy during the interaction of the enzyme with the fluorochromes are also given. [ABSTRACT FROM AUTHOR]

1. Fractionation of antitransaminase or anti-whole-tryptic transaminase hydrolysate anti- bodies was accomplished by using solid conjugates of the enzyme or its whole-tryptic hydrolysate with albumin. By miring in different orders, the solid complexes with antiserums prepared alter immunization of experimental animals with transaminase or it hydrolysate, four antibody fractions (A B C and I)) were isolated. 2. The antibody reactivity of the isolated fractions was tested by micro-complement fixation, inhibition of the catalytic activity of the enzyme and haemagglutination. It was found that fractions B and C exhibited more reactivity with the intact transaminase molecule, while A and D reacted more specifically with the various fragments of the enzyme hydrolysate. 3. After fractionation of the proteolytic hydrolysate through a Sephadex G-25 column, it was found that high molecular weight peptides were more reactive against the antibody fractions A and I), which reacted specifically with the hydrolysate. On the contrary, low molecular weight peptide8 reacted more intensively with the antibody fractions B and C, specific for the intact transaminase molecule. 4. Heterogeneity of the isolated antibody fractions, as well as of the total population of antibodies against transaminase or its whole tryptic hydrolysate, has been demonstrated by analytical acrylamide disc electrophoreisis; and isoelectric focusing. [ABSTRACT FROM AUTHOR]

1. Tryptic hydrolysates of denaturated glutamic-aspartic transaminase fractionated on a Sephadex G-25 column, gave an elution diagram containing six main fractions. When peptide maps were developed from the transaminase digest 37 spots were detected on the paper sheet. 2. It was demonstrated that the transaminase fractions (groups of peptides) as well as some of the individual peptides eluted from the map spots, possessed immunological activity. This was proved by their capacity to interact with rabbit pig heart antienzyme and rabbit antiserum against the pig-heart whole tryptic transaminase hydrolysate as well as to inhibit the homologous transaminase-antitransaminase reaction. Higher immunological reactivity was found among peptides moving faster in electrophoresis and chromatography. 3. The catalytic activity of rabbit transaminase (heart, liver, skeletal muscles), was inhibited to a substantial degree by the rabbit anti-pig heart transaminase. The above enzymes however, as was otherwise expected, gave negative precipitin reactions with antitransaminase. A comparative study of the reactivity between transaminases from pig, ox and rabbit and rabbit anti-transaminase against pig and ox heart enzymes as well as against pig-heart whole tryptic transaminase hydrolysate is presented here. [ABSTRACT FROM AUTHOR]

Focuses on the role of ethylenediaminetetraacetic acid (EDTA) in searching for heat-stable low-Mr inhibitors of protein kinases. Presence of EDTA in the homogenization buffer from the diethylaminothanol-cellulose column; Detection of an increased conductivity of phosphorylase-kinase-inhibitory fractions after heating; Release of EDTA at high ionic strength.