Alkaline Phosphatase Activity in Seawater: Influence of Reaction Conditions on the Kinetic Parameters of ALP

Alkaline phosphatase (ALP) is an extracellular enzyme enabling utilisation of phosphomonoesters as the source of inorganic phosphate (Pi) required for the maintenance of cellular metabolism. Its catalytic properties have been extensively studied in aquatic environments in an attempt to describe its influence on phosphorous cycling in natural waters. Despite its significance and frequent determination, no standard method has been developed so far. In order to examine the effect of various reaction conditions on the kinetic properties of ALP in seawater, the stability of ALP in chloroform-stabilised samples has been studied in addition to the influence of the buffer type, its concentration and pH, the metal-ion content, Pi and incubation time. It might be concluded that the kinetic properties of ALP are significantly influenced by the buffer pH, the concentration of Mg2+ and Zn2+ ions and the incubation period, requiring a precise definition of these reaction parameters in determining a standard method for the measurement of ALP activity in water media

Paralytic Shellfish Poisoning (PSP) in the Central Adriatic Sea

Surveillance of Paralytic Shellfish Poisoning (PSP) in the Ka{tela Bay, Central Adriatic Sea, was conducted in the summers of 1995 through 1997. Toxicity was assessed by the mouse bioassay according to the method proposed by the Association of Official Analytical Chemists (AOAC). Incidence of shellfish intoxication by PSP toxins was recorded on several occasions, however at levels not endangering human health. Along with shellfish sampling, seawater samples were taken for analysis of the phytoplankton community and the numerical cell abundance. The phytoplankton composition demonstrates a recurring incidence of Lyngulodinium polyedra, and frequent presence of species from the Alexandrium, Gymnodinium and Gyrodinium genera, well known progenitors of PSP and its analogues. Possible recurrence of such phenomena and their distribution to other regions of the Adriatic coast may have serious health and economic consequences, calling for continuous monitoring of phytoplankton composition and toxicological studies of shellfish

Stereoselective Transformations in the Thymidine Series

The s tereoselective 5% Rh/ AliOa hydrogenations Olf .thymidine, 3\u27,5\u27-anhydro- X and 3\u27-deoxy- XII thymidines to -the corresipondiing (5S) - 5,6-d1hydirothymi!di..ne deirivaitiv1es I, IX, and XIII were evLdenced by 1H- and 13C-NMR analyses and N-.glycosidix! bo1I1d cleaV\u27ages .to (-)-S-5,6-dihydrot:hymine. Th:e regiose ·lect.ive syntiheses 01f the configuraotionally defined (58)-5\u27- 0-tosyl- (Ill) and (5\u27S)-5\u27-deoxy-5\u27-iodo- (IV) 5,6-dihydrothymidines aire descriibed. The tntramolecular cyC\u27lisat.ion of (5S) - 3\u27,5\u27-dimesyloxy-5,6- -dihydrothymidine (II) by NaiOMe afforded (5R,5S)-5\u27-0-mesy.I- -2,3\u27 -anhydro- 5,6-dihydrothym.idines <VD, which concomitantly proceeded to ring opened (5R , 5S)-\u271-(2-deoxy - 5-0-mesyl- ~ -D- threo-ipentorfuranosyl)-2-0-methyl-5,6-dihydrothymine (VL!) and, iinally, from the lat teir into {5R,5S)-1-(2-deoxy-3,5-anhydro-~- D-1illl"\u27i00-ipeinto1uranosy.l) -2-0-met:hyl-5,6-dihydr.oithymi!ne (VCEll) . 5,6-Dihydropyrimidin

Toxin Levels and Profiles in Microalgae from the North-Western Adriatic Sea—15 Years of Studies on Cultured Species

The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication due to shellfish consumption occurred in 1989, nearly 10 years later than other countries in Europe and worldwide that had faced similar problems. Until 1997, Adriatic mollusks had been found to be contaminated mostly by diarrhetic shellfish poisoning toxins (i.e., okadaic acid and dinophysistoxins) that, along with paralytic shellfish poisoning toxins (i.e., saxitoxins), constitute the most common marine biotoxins. Only once, in 1994, a toxic outbreak was related to the occurrence of paralytic shellfish poisoning toxins in the Adriatic coastal waters. Moreover, in the past 15 years, the Adriatic Sea has been characterized by the presence of toxic or potentially toxic algae, not highly widespread outside Europe, such as species producing yessotoxins (i.e., Protoceratium reticulatum, Gonyaulax spinifera and Lingulodinium polyedrum), recurrent blooms of the potentially ichthyotoxic species Fibrocapsa japonica and, recently, by blooms of palytoxin-like producing species of the Ostreopsis genus. This review is aimed at integrating monitoring data on toxin spectra and levels in mussels farmed along the coast of the Emilia-Romagna region with laboratory studies performed on the species involved in the production of those toxins; toxicity studies on toxic or potentially toxic species that have recently appeared in this area are also reviewed. Overall, reviewed data are related to: (i) the yessotoxins producing species P. reticulatum, G. spinifera and L. polyedrum, highlighting genetic and toxic characteristics; (ii) Adriatic strains of Alexandrium minutum, Alexandrium ostenfeldii and Prorocentrum lima whose toxic profiles are compared with those of strains of different geographic origins; (iii) F. japonica and Ostreopsis cf. ovata toxicity. Moreover, new data concerning domoic acid production by a Pseudo-nitzschia multistriata strain, toxicity investigations on a Prorocentrum cf. levis, and on presumably ichthyotoxic species, Heterosigma akashiwo and Chattonella cf. subsalsa, are also reported