Use of β-hydroxyacyl-CoA-dehydrogenase (HADH) activity to differentiate frozen from unfrozen fish and shellfish

 Further work on an enzymic method to differentiate frozen from unfrozen fish and shellfish is reported. The method is based on the release of the β-hydroxyacyl-CoA-dehydrogenase (HADH) from mitochondria during freezing. Enzymic activity was evaluated in fresh and frozen thawed samples from sole (Solea solea), sea bream (Pagellus centrodontus), hake (Merluccius merluccius), gilt headed bream (Sparus aurata), sea bass (Dicentrarchus labrax), salmon (Salmo salar), prawn (Penaeus japonicus) and Norwegian lobster (Nephrops norvegicus). Changes in the HADH activity of fresh and frozen thawed samples were compared after freezing at –196  °C for 15 min. Two values were obtained: U (by dividing: HADH activity of samples frozen at –196  °C, then thawed/HADH activity of unfrozen samples) and F (by dividing: HADH activity of samples frozen at –18  °C, thawed, then frozen at –196  °C /HADH activity of samples frozen at –18  °C, then thawed). Statistical analysis showed significant differences (P≤0.05) between both quotients for gilt headed bream, salmon, sea bream, sole and prawn, and an arbitrary limit was set at 2 to differentiate frozen thawed from unfrozen samples. The application of this limit made it possible to discriminate the unfrozen from the frozen thawed state of around 90% of the total samples analysed. Best results were obtained for prawn (100% of samples differentiated). In the present paper, a laboratory routine is proposed based on the comparison of the HADH activity of a sample analysed straight away and that of a sample frozen at –196  °C and then thawed. The reported method is simple and fast. The entire laboratory procedure can be performed in 45 min. Received: 20 July 1998 / Revised version: 2 November 1998     

Physiological response to persistent organic pollutants in fish from mountain lakes: analysis of CYP1A gene expression in natural populations of Salmo trutta

Cytochrome p450 1A (CYP1A) gene expression in fish liver increases upon exposure to a variety of chemical compounds, including organochlorine compounds (OCs) and polycyclic aromatic hydrocarbons (PAHs). To use this physiological response as a marker of environmental impact, we developed and validated a set of primers to quantify CYP1A expression by qRT-PCR in the brown trout, Salmo trutta. These primers were used to explore the natural variability of CYP1A expression in 8 isolated populations (65 samples) from European remote lakes, in a geographical distribution encompassing the Tyrolean Alps, Pyrenees, Rila, Tatras, and Norwegian and Scottish mountains. CYP1A expression values varied more than 2 orders of magnitude among samples, with strong variations within each population. CYP1A expression values were significantly elevated in Tatras and Pyrenees fish populations, whereas the lowest median values were found in populations from the Tyrolean Alps and Rila. These values correlated with the content of different environmentally relevant pollutants in the sediments of the lakes harboring each fish population, particularly with HCB and 4,4'-DDE contents. To our knowledge, this works represents a first report of a physiological response linked to persistent organic pollutants in fish from mountain lakes.     

Development of spoilage microbiota in beef stored in nisin activated packaging

The aim of this study was to assess the microbial populations causing the spoilage of chilled beef during storage and to evaluate the effect of the use of an antimicrobial packaging for the meat storage. A nisin activated antimicrobial packaging was developed by using a nisin, HCL and EDTA solution and used for the storage of beef cuts at 1 °C. The common spoilage related microbial groups were monitored during the storage of beef in activated and non activated plastic bags by using selective media. The use of the antimicrobial packaging caused an overall significant reduction of viable counts of Gram positive bacteria such as carnobacteria, lactic acid bacteria and Brochotrix thermosphacta whose development was inhibited for at least 11 days of storage compared to the control. Moreover, a 1–3 log cycles reduction of enterobacteria was also registered between 22 and 32 days of storage. The microbiota was assessed at species level by using Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA gene of DNA extracted directly from meat and from bulk cells from selective media plates and showed that the species occurring within the targeted microbial groups did not change according to storage conditions. In conclusion, the use of the nisin activated packaging reduced the number of spoilage populations but did not affect the species diversity. Improved antimicrobial packaging is needed, possibly coupled with vacuum storage, to possibly achieve a simultaneous inhibition of more spoilage microbial groups and to preserve the microbiological quality of beef during chilled storage.     

Characterisation of Bobal and Crujidera grape cultivars,in comparison with Tempranillo and Cabernet Sauvignon: Evolution of leaf macronutrients and berry composition during grape ripening

We present characterisation data for two Spanish autochthonous grapevines, Bobal and Crujidera, in comparison with the well-known cultivars Tempranillo and Cabernet Sauvignon. Microsatellite markers were used for the molecular characterisation of Crujidera grapevines. Leaf macronutrient contents of the four cultivars were evaluated, as well as their changes at different vine developmental stages, and veraison was seen as the most suitable time to evaluate the nutritional status. Quantitative changes in some physiological parameters and the phenolic composition of the four grape varieties were measured during the last month of ripening. Polyphenols, tannins and anthocyanins increased with grape maturation, although the accumulation of these phenolic compounds and their patterns of evolution varied considerably with the cultivar. The biosynthetic potential of these grapes to produce resveratrol largely depended on the grape variety, with a remarkably high content found in Bobal berry skins.     

Production of a yogurt-like product from plant foodstuffs and whey. Substrate preparation and fermentation

A mixed substrate composed of soya milk, oat flour and dried cheese whey (82, 11 and 7% respectively) had a content of lactose and protein similar to that of milk used for yogurt manufacture. Heat treatment for 20 min at 80°C resulted in a viscosity similar to that of yogurt whilst removing coliform and mesophilic aerobic bacteria, moulds and yeasts. Fermentation with traditional yogurt bacteria did not increase viscosity further, and the final product had similar acidity and texture to yogurt. Acid development, carbohydrate consumption, proteolysis and starters counts were followed during fermentation. The fermentation profile of the mixed substrate was very similar to that of milk.     

Zein‐based ultrathin fibers containing ceramic nanofillers obtained by electrospinning. II. Mechanical properties,gas barrier,and sustained release capacity of biocide thymol in multilayer polylactide films

The combination of electrospinning technology and nanomaterials such as nanoclays can synergistically lead to novel materials with enhanced properties and functionalities for their usage in passive and active packaging applications. Part I of this work was focused on the development of ultrathin zein fibers containing nanoclays, which were oriented along the fiber axis and increased the thermal properties. Part II presents the use of the hybrid fibers as passive and active components in multilayer packaging structures. The hybrid fibers are incorporated in poly(lactic acid) films via a two‐step process: Electrospinning and compression molding. The composites thus produced presented improved mechanical and barrier properties than the unfilled material. The natural biocide extract thymol is then incorporated in the coating, and its sustained release properties are shown. The antimicrobial capacity of the hybrid fibers was also determined against foodborne bacteria. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40768.     

Human iPSC-Derived Astrocytes: A Powerful Tool to Study Primary Astrocyte Dysfunction in the Pathogenesis of Rare Leukodystrophies

Astrocytes are very versatile cells, endowed with multitasking capacities to ensure brain homeostasis maintenance from brain development to adult life. It has become increasingly evident that astrocytes play a central role in many central nervous system pathologies, not only as regulators of defensive responses against brain insults but also as primary culprits of the disease onset and progression. This is particularly evident in some rare leukodystrophies (LDs) where white matter/myelin deterioration is due to primary astrocyte dysfunctions. Understanding the molecular defects causing these LDs may help clarify astrocyte contribution to myelin formation/maintenance and favor the identification of possible therapeutic targets for LDs and other CNS demyelinating diseases. To date, the pathogenic mechanisms of these LDs are poorly known due to the rarity of the pathological tissue and the failure of the animal models to fully recapitulate the human diseases. Thus, the development of human induced pluripotent stem cells (hiPSC) from patient fibroblasts and their differentiation into astrocytes is a promising approach to overcome these issues. In this review, we discuss the primary role of astrocytes in LD pathogenesis, the experimental models currently available and the advantages, future evolutions, perspectives, and limitations of hiPSC to study pathologies implying astrocyte dysfunctions.     

Aquaporins Are One of the Critical Factors in the Disruption of the Skin Barrier in Inflammatory Skin Diseases

The skin is the largest organ of the human body, serving as an effective mechanical barrier between the internal milieu and the external environment. The skin is widely considered the first-line defence of the body, with an essential function in rejecting pathogens and preventing mechanical, chemical, and physical damages. Keratinocytes are the predominant cells of the outer skin layer, the epidermis, which acts as a mechanical and water-permeability barrier. The epidermis is a permanently renewed tissue where undifferentiated keratinocytes located at the basal layer proliferate and migrate to the overlying layers. During this migration process, keratinocytes undertake a differentiation program known as keratinization process. Dysregulation of this differentiation process can result in a series of skin disorders. In this context, aquaporins (AQPs), a family of membrane channel proteins allowing the movement of water and small neutral solutes, are emerging as important players in skin physiology and skin diseases. Here, we review the role of AQPs in skin keratinization, hydration, keratinocytes proliferation, water retention, barrier repair, wound healing, and immune response activation. We also discuss the dysregulated involvement of AQPs in some common inflammatory dermatological diseases characterised by skin barrier disruption.