Effects of dietary vitamin B6 supplementation on fillet fatty acid composition and fatty acid metabolism of rainbow trout fed vegetable oil based diets

Fish oil replacement in aquaculture feeds results in major modifications to the fatty acid makeup of cultured fish. Therefore, in vivo fatty acid biosynthesis has been a topic of considerable research interest. Evidence suggests that pyridoxine (vitamin B(6)) plays a role in fatty acid metabolism, and in particular, the biosynthesis of LC-PUFA has been demonstrated in mammals. However, there is little information on the effects of dietary pyridoxine availability in fish fed diets lacking LC-PUFA. This study demonstrates a relationship between dietary pyridoxine supplementation and fatty acid metabolism in rainbow trout. In particular, the dietary pyridoxine level was shown to modulate and positively stimulate the activity of the fatty acid elongase and Δ-6 and Δ-5 desaturase enzymes, deduced by the whole-body fatty acid balance method. This activity was insufficient to compensate for a diet lacking in LC-PUFA but does highlight potential strategies to maximize this activity in cultured fish, especially when fish oil is replaced with vegetable oils.     

Effects of Spirulina and plant oil on the growth and lipid traits of white sturgeon (Acipenser transmontanus) fingerlings

The aim of this research was to evaluate the efficiency of diets with Spirulina and plant oils (POs) inclusion for white sturgeon weaning and their effects on the fatty acid (FA) composition of fish flesh. Three isoproteic (45%) and isoenergetic (21 MJ kg^?1 DM) diets were formulated: one fish meal‐based diet integrated with fish oil (FMO) and two 40% Spirulina meal‐based diets integrated with corn (SPC) or soybean (SPS) oils respectively. One hundred and thirty‐five white sturgeon fingerlings (mean weight 17.5 g) were stocked randomly in nine fibreglass tanks. At the end of the trial, which lasted 71 days, the growth performance traits and somatic indexes were determined. The chemical composition, gross energy and FA profile were determined on the fish fillets. No significant effects were observed for the growth performances or fillet chemical composition. The FA profile of the fillets reflected those of the diets. In particular, the fillets of the fish fed with the SPC and SPS diets were lower in n‐3 FA, due to the substitution of fish oil (FO) with POs. It is possible to replace FO and meal in sturgeon; therefore, Spirulina meal integrated with POs could be a good alternative to sturgeon diet.     

Formulation of New Media from Dairy and Brewery Wastes for a Sustainable Production of DHA-Rich Oil by Aurantiochytrium mangrovei

Mozzarella stretching water (MSW) is a dairy effluent generated from mozzarella cheese production that does not have a real use and is destined to disposal, causing environmental problems and representing a high disposal cost for dairy producers. Spent brewery yeast (SBY) is another promising food waste produced after brewery manufacturing that could be recycled in new biotechnological processes. Aurantiochytrium mangrovei is an aquatic protist known as producer of bioactive lipids such as omega 3 long chain polyunsaturated fatty acids (ω3 LC-PUFA), in particular docosahexaenoic acid (DHA). In this work MSW and SBY have been used to formulate new sustainable growth media for A. mangrovei cultivation and production of DHA in an attempt to valorize these effluents. MSW required an enzymatic hydrolysis to enhance the biomass production. The new media obtained from hydrolysed MSW was also optimized using response surface methodologies, obtaining 10.14 g L⁻¹ of biomass in optimized medium, with a DHA content of 1.21 g L⁻¹.     

Simplified extraction method for ELISA and PCR detection of potato leafroll luteovirus primary infection in dormant potato tubers

This report describes a simple, rapid and inexpensive procedure for sampling large numbers of dormant tubers for analysis of potato leafroll luteovirus (PLRV) infection. The procedure uses a common electric drill to simultaneously remove and macerate tuber-eye samples for detection of PLRV by the enzyme-linked immunosorbant assay (ELISA) and the polymerase chain reaction (PCR). By using these sampling and analysis approaches, 19 of 20 different PLRV isolates were detected in dormant tubers from plants with primary infections. Results from the dormant tuber analysis, were verified by planting the tubers and testing leaf tissue by ELISA and PCR. Similar sampling and testing done on healthy dormant tubers and sprouts from the tubers consistently gave negative results as expected.     

Isotopic Model (NISOTOP) used to Investigate 15N-Urea Transformations in the Presence of Phenanthrene,Chrysene and Benzo(a)pyrene in a Soil–Plant System

An isotopic model (NISOTOP) has been developed to investigate the effect of the addition to soil of xenobiotics on urea hydrolysis, N mineralization and immobilization, nitrification and plant uptake of nitrogen in a soil-plant system, after addition of ¹⁵N enriched compounds. Therationale of the model follows from the errors in %¹⁵N abundance (^15N _D) and N concentration (C_N) determinations which cause high variability coefficients in the calculation of the amount of nitrogen present in the different compounds derived from the added ¹⁵N enriched urea. The extent of these errors, besides depending on C_N and ^15N _D errors, will also depend on natural ¹⁵N and ¹⁵N of the added compound, and therefore on the experimental conditions. The model is described by 18 first-order differential equations and is numerically solved by Euler's method with a time increment of 0.01 day. As an illustration, the model is applied to the effect of phenanthrene, chrysene and benzo(a)pyrene to a soil-plant system, following the addition of ¹⁵N-urea. These compounds have been chosen as examples of molecules having 3, 4 and 5 fused aromatic rings and are hereafter collectively referred to as PAHs. PAHs at the rate of 2 mg kg^-1 soiland ¹⁵N-urea at the rate of 166.7 mg N kg^-1 soil were added to wheat pots. At harvesting (after 14 days from plantation) the dry matter yield, the total N content and the N concentration of the wheat seedlings were not statistically affected by addition of the PAHs (P = 0.05). The efficiency of N uptake, that is the percentage of fertilizer taken up by the plants at harvesting in the absence of PAHs was 47.3%, while it was 11.7, 15.2 and 14.8% in the presence of phenanthrene, chrysene and benzo(a)pyrene,respectively. The computation of the first-order rate constants of the N transformations showed that N mineralization, nitrification and N-uptake were affected by the addition of phenanthrene, chrysene and benzo(a)pyrene, whilst benzo(a)pyrene inhibited urea hydrolysis more than phenanthrene and chrysene.     

Book reviews

Agriculture and Human Values -     

Residents and urban green spaces: The case of Bari

The total area of public green spaces in the city of Bari, Italy is more limited than in most other Italian cities (2.9 m²/inhabitant). This fact makes it an interesting subject for research into the general perception that the residents of the city have of green spaces and their behaviour patterns when using them.

A questionnaire (27 questions) was presented by telephone to a representative sample (n=351) of the population of Bari. The aims of the study were: (a) to gain insight in the perception of green spaces with particular reference to those green areas within the city itself; (b) to examine behaviour during visits to parks and gardens and means of transport used to reach them; (c) to investigate what kind of relationship should be set up between the local authority and the population regarding information and participation.

The results show that respondents perceive the green areas as a life quality enhancer in accordance with some previous studies carried out in Italy and in other countries. Citizens are moreover conscious of the limitations in quality and quantity of green areas in their own city, although this result needs to be more closely analysed in the future. Patterns in the use of public green areas proved to be strictly connected with age, sex, marital status, area of residence. Another conditioning factor was the system of mobility. The results moreover underline how citizens see the public and private green areas as single beneficial system.

The research also demonstrates the potentials of applying telephone surveys in studies concerning urban forests.     

Tissue culture methods for the screening and analysis of putative virus-resistant transgenic potato plants

ABSTRACT Following regeneration, putative virus-resistant transgenic plants are usually transferred from tissue culture to a greenhouse or growth chamber to screen for resistance to infection and disease development using mechanical, graft, or insect vector inoculation methods. To reduce initial screening costs and time, we developed mechanical and graft inoculation methods suitable for tissue culture use. The in vitro methods were validated by comparing them with similar greenhouse screens using putative potato virus Y strain o (PVY degrees ) replicase-mediated resistant regenerants of the potato cultivar Atlantic. Five transgenic lines were tested, with similar results obtained from in vitro and greenhouse experiments. Two of the transgenic lines, A1 and A3, showed the greatest resistance to PVY degrees infection, as indicated by low enzyme-linked immunosorbent assay values and infection rates. In vitro mechanical inoculation methods were also used to infect wild-type tomato and tobacco plants with cucumber mosaic virus and potato virus Y. Potato plants were also infected with the phloem-restricted potato leafroll virus, a low-titer virus, using in vitro graft inoculation methods. These results suggest the potential usefulness of these simple, effective, and economical techniques for screening large numbers of putative virus-resistant plants.     

Rearing experiences of the polychaete Sabella spallanzanii in the Gulf of Taranto (Mediterranean Sea,Italy)

In order to utilize the biomass of the polychaete Sabella spallanzanii Gmelin as a dietary supplement for fish nourishment, we conducted some experiences of rearing this worm in the Mediterranean Sea. A preliminary study on the growth of this species on suspended plastic nets was conducted in two sites of the Apulian coast with different trophic features. Data for the first 12 months show that S. spallanzanii reared in eutrophic conditions grows producing a biomass higher than the natural population. The acquired experience was afterward tested in a pilot plant located in the Mar Piccolo of Taranto, a eutrophic area where polychaetes were co-cultured with Mytilus galloprovincialis within a long-line farm. The slight mortality recorded during the first 2 months and quite negligible after 4 months, the high increase in volume and biomass of the reared polychaetes, especially at high density (70 individuals for each net), demonstrated the advantage of rearing S. spallanzanii in the pilot plant with low cost of production and high profit. If the acquired technology is applied to a medium farm containing up to 400 sectors, the biomass produced indeed might reach about 1.36 tons/year. In conclusion, on the basis of our results, we demonstrated the possibility to obtain high-value worm biomass coupled to mussel biomass in a completely non-fed culturing system without increasing, but presumably reducing the environmental impact due to mussel farming.