Vitelline coat of Unio elongatulus: II. Biochemical properties of the 220- and 180-kD components

In a previous study we found that two glycoproteins with apparent molecular weights of 220 kD and 180 kD account for 80–90% of the material dissolved from the vitelline coat of the egg of the bivalve mollusk, Unio elongatulus (Focarelli and Rosati, 1993: Mol Reprod Dev 35:44–51). In this study we isolated and purified these glycoproteins by electroelution. The two proteins differ in many respects: the 180-kD molecule is acidic in nature and highly heterogeneous, whereas the 220-kD protein is neutral and less heterogeneous. Both seem to have O- and N-linked oligosaccharide chains. The 180-kD protein contains 13–16% carbohydrate, whereas the 220-kD molecular contains only 7–8%. Amino acid analysis and peptide mapping also show that each protein represents a unique polypeptide chain. © 1995 Wiley-Liss, Inc.     

Glycosphingolipid metabolic reprogramming drives neural differentiation

Neural development is accomplished by differentiation events leading to metabolic reprogramming. Glycosphingolipid metabolism is reprogrammed during neural development with a switch from globo‐ to ganglio‐series glycosphingolipid production. Failure to execute this glycosphingolipid switch leads to neurodevelopmental disorders in humans, indicating that glycosphingolipids are key players in this process. Nevertheless, both the molecular mechanisms that control the glycosphingolipid switch and its function in neurodevelopment are poorly understood. Here, we describe a self‐contained circuit that controls glycosphingolipid reprogramming and neural differentiation. We find that globo‐series glycosphingolipids repress the epigenetic regulator of neuronal gene expression AUTS2. AUTS2 in turn binds and activates the promoter of the first and rate‐limiting ganglioside‐producing enzyme GM3 synthase, thus fostering the synthesis of gangliosides. By this mechanism, the globo–AUTS2 axis controls glycosphingolipid reprogramming and neural gene expression during neural differentiation, which involves this circuit in neurodevelopment and its defects in neuropathology.     

Binding of biotin to hepatitis B surface antigen: a possible pitfall in immunohistochemistry

We report on the binding of biotin, and hence of biotinylated antibodies and lectins, to ground glass hepatocytes and liver cell membranes in chronic hepatitis B viral infection. This binding is of low affinity, and was proved to be directed at the hepatitis B surface antigen, presumably at its disulfide bonds. To avoid false-positive results, this affinity should be considered in the interpretation of immunohistochemical stainings of hepatitis B virus-infected liver tissue with biotinylated reagents.     

Life Cycle assessment of a plastic packaging recycling system

Goal, Scope and Background.  The object of the study is the Italian system of plastic packaging waste recycling, active until 2001, that collected and mechanically recycled the post-consumer PE and PET liquid containers. The phases of collection, compaction, sorting, reprocessing and refuse disposal were individually analysed and quantified in terms of energy and material consumptions as well as of emissions in the environment. The work is the result of a joint research project with the Italian Consortium for Packaging (CONAI), carried out in co-operation with the main Italian companies active in the field. The main aim was the quantification of the real advantage of plastic container recycling and the definition of criteria, at the same time environmentally compatible and economically sustainable, for their management. Main Features  For each of the unit processes, and in order to increase the data quality, all the data of interest were collected during technical visits to several selected plants active in Italy or deduced by official documents and certificate declarations of the same companies. To allow comparison of resource consumption and environmental pollution from different management scenarios producing different products, thebasket of products method was applied. Results  The results indicates that the production of 1 kg of flakes of recycled PET requires a total amount of gross energy that is in the range of between 42 and 55 MJ, depending on whether the process wastes (mainly coming from sorting and reprocessing activities) were sent or not to the energy recovery. The same quantity of virgin PET requires more than 77 MJ. The energetic (and then environmental) saving is so remarkable, even for PE, being 40–49 MJ for the recycled polymer and about 80 MJ that for the virgin polyolefin. The calculations were made with the reasonable assumption that the final utilisation can use the virgin or the recycled polymer without any difference. Conclusions and Outlook  The analysis defined and verified a suitable tool in the field, based on objective data, for comparing different coherent scenarios of waste management politics. This allows one to propose the extension of the tool under different collection schemes, as well as for different systems of packaging recycling. As an immediate consequence of the success of the present study, the joint-research programme with CONAI has been extended for another three years. The focus will be the Italian system for paper and paperboard recycling and that for all plastic packagings. In parallel, a different study has been scheduled with reference to the integrated solid waste management of the Regione Campania, the largest and most populated area in the South of Italy.     

Vitelline coat of Unio elongatulus egg: I. Isolation and biochemical characterization

In this study we isolated and purified the vitelline coat (vc) of Unio elongatulus eggs in order to investigate its protein and carbohydrate composition. SDS dissolved up to 80% of the vitelline coat protein content whereas 100 mM Ammonimum acetate (AA) at pH 11 and 1 mM lithium diiodosalicylate (LISH) dissolved only 40–50%. The ability of extremes of pH or LIS to solubilize the vitelline coats on eggs was then investigated. The results showed that pH from 7 to 11 progressively dissolved the vitelline coats without gross damage to the oocytes. SDS-PAGE of the solubilized material revealed only two components corresponding to the main components revealed by SDS-PAGE of the isolated vcs. These peptides have an apparent MW of 220 and 180 kD, are ConA positive, and seem to be connected to each other to form polycomponents. The latter feature is suggested by the electrophoretic pattern of the solubilized material under nondenaturing conditions. © 1993 Wiley-Liss, Inc.     

Sperm-egg interaction in the mouse using live and glutaraldehyde-fixed eggs

A study of interaction between gametes in the mouse, using live and glutaraldehyde-fixed eggs, showed that, while in live eggs the binding is a two-step process (“early” and “late” binding), the process is one step when the spermatozoa interact with fixed eggs. The second point that emerged from this study is that uncapacitated and capacitated spermatozoa bind the zonae pellucidae of live and fixed eggs in the same way, but only the capacitated spermatozoa bound to live eggs undergo a complete acrosome reaction and penetrate the zona pellucida. Moreover, it has been shown that binding to fixed eggs, just as to live eggs, is Ca²⁺-dependent, and it can be reversed by EGTA. Fixed eggs thus are a good model to study only one step of the sperm-egg interaction removed from all the other events of the fertilization process.