Microalgae n-3 PUFAs Production and Use in Food and Feed Industries

N-3 polyunsaturated fatty acids (n-3 PUFAs), and especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential compounds for human health. They have been proven to act positively on a panel of diseases and have interesting anti-oxidative, anti-inflammatory or anti-cancer properties. For these reasons, they are receiving more and more attention in recent years, especially future food or feed development. EPA and DHA come mainly from marine sources like fish or seaweed. Unfortunately, due to global warming, these compounds are becoming scarce for humans because of overfishing and stock reduction. Although increasing in recent years, aquaculture appears insufficient to meet the increasing requirements of these healthy molecules for humans. One alternative resides in the cultivation of microalgae, the initial producers of EPA and DHA. They are also rich in biochemicals with interesting properties. After defining macro and microalgae, this review synthesizes the current knowledge on n-3 PUFAs regarding health benefits and the challenges surrounding their supply within the environmental context. Microalgae n-3 PUFA production is examined and its synthesis pathways are discussed. Finally, the use of EPA and DHA in food and feed is investigated. This work aims to define better the issues surrounding n-3 PUFA production and supply and the potential of microalgae as a sustainable source of compounds to enhance the food and feed of the future.     

Teleost fish osteocalcin 1 and 2 share the ability to bind the calcium mineral phase

The occurrence of a second osteocalcin (OC2) has been reported in teleost fish, where it coexists with OC1 in some species. While it has been proposed that OC2 gene originated from OC1 through the fish whole-genome duplication event, little information is available on its molecular function and physiological role. The present study brings biological data supporting the presence of OC2 in the mineral phase of teleost fish bone and its association with the mineral phase together with OC1. The occurrence of OC2 forms with different levels of phosphorylation or γ-carboxylation, and with amino acid substitutions was observed. Comparative analysis of mature peptide sequences revealed the high conservation existing between OC1 and OC2, in particular within the core γ-carboxyglutamic acid domain, and suggests that both protein forms may have the same function, i.e., binding of calcium ions or hydroxyapatite crystals.     

Establishment of optimal conditions for long-term culture of erythrocytic stages of Theileria uilenbergi

OBJECTIVE: To establish optimal conditions for long-term culture of the erythrocytic stage of Theileria uilenbergi. SAMPLE POPULATION: Red blood cells from 3 splenectomized sheep experimentally infected with a blood stabilate of T uilenbergi. PROCEDURES: Cultures of T uilenbergi were initiated by use of blood from experimentally infected sheep collected when parasites were detected in Giemsa-stained thin blood smears. Different culture conditions were tested to optimize in vitro growth of the organisms. Subcultures were performed at a ratio of 1:2, 1:4, and 1:8 when the percentage of parasitized erythrocytes (PPE) was at least 1% or when the initial PPE was doubled. RESULTS: The optimal culture medium was HL-1 medium (a complete chemically defined medium) supplemented with 20% sheep serum and 0.75% chemically defined lipids. Optimal culture conditions included incubation in a humidified 2% O(2), 5% CO(2), and 93% N(2) atmosphere at 37 degrees C. Cultures of the merozoite stage of the parasite were continuously propagated in vitro for > 1 year. The PPE reached values of up to 3%. CONCLUSIONS AND CLINICAL RELEVANCE: Optimization of culture conditions to reach a high PPE seems worthwhile. The continuous propagation of T uilenbergi in culture allows the production of parasite material without infecting animals and provides a continuous laboratory source of parasites for further studies.     

Analysis of variables influencing tree cork caliper in two consecutive cork extractions using cork growth index modelling

The influence of tree and stand variables, debarking intensity, and precipitation on the caliper of cork produced by a tree and on the evolution of cork caliper between consecutive cork extractions was researched. A total of 370 cork samples were collected in 23 permanent plots distributed across the cork production area in Portugal, covering a period from 1984 to 2010. Cork growth was evaluated using the cork growth index (cgi), defined as the radial width of the first eight complete years of cork growth after stripping. The differences in mean cgi at plot level between two consecutive cork growth periods (cgp) were assessed using nonparametric tests. A mixed model approach was used due to the nested structure of the data for modelling cgi value at tree level. The cgi of two consecutive cork extractions is linearly related at tree level. At plot level, the mean value of cgi decreased in 5 out of the 23 plots and increased in 2 plots for α = 0.05. The number of debarked branches and the variation of precipitation between two cgp were the variables that explained the largest part of the cgi evolution. However, significance of plot random parameters indicates that other variables are involved in the tree cgi evolution, pointing out to the need of further research. Tree size and precipitation during the cgp are related to the individual tree cgi. The effect of increasing stand density and debarking intensity on cork growth was not clear. Long term research based on permanent plot measurements and research trials is needed to clarify the impact of tree competition and debarking intensity.     

Does debarking intensity during the first cork extraction affect future cork thickness?

Key message

The use of increasing debarking during the first harvest of cork oak trees ( Quercus suber L.) had no effect on the secondary cork calliper (thickness) in one of the trials and had a small negative effect in a second trial. Little evidence was found that debarking coefficient is a useful index for the management of cork oak stands.

Context

The Portuguese national legislation defines, without the support of scientific data or knowledge, maximum values of debarking coefficients (ratio of debarking height and perimeter at breast height measured over cork). For the first debarking, this value is limited to 2.0.

Aims

The aim of this study was to determine the impact of increasing cork debarking coefficient on the calliper of the secondary cork extraction.

Methods

Trees were located in two sites, in distinct regions characterized by low or high productivity classes. Three debarking coefficients were considered: 1.5, 2.0 and 2.5. The debarking coefficient for the first cork extraction was randomly selected for each tree. During the second debarking, a cork sample was taken from each tree. The samples were used for assessing secondary cork calliper. Differences in cork calliper were analysed using both correlation analysis and modelling approaches.

Results

Debarking intensity increase had a small negative effect on secondary cork thickness in the most inland site, while no effect was detected in the more coastal site.

Conclusion

In our experiment, debarking intensity had a significant but small effect in one site and no effect in other sites. Debarking coefficients not only should be defined according to legal constraints but also instead should be adapted considering tree and site characteristics.

     

Resveratrol induces apoptosis through ROS-dependent mitochondria pathway in HT-29 human colorectal carcinoma cells

trans-Resveratrol is a polyphenol found in blueberries, grapes, and wine with cancer chemopreventive properties. The low bioavailability of this compound enhances its concentration in the luminal content and becomes a potential chemopreventive agent against colon cancer. In the present study, the antiproliferative and pro-apoptotic effects on the human colorectal carcinoma HT-29 cells as well as the mechanisms underlying these effects were examined. Proliferation, cytotoxicity, and apoptosis were measured by fluorescence-based techniques. Studies of dose-dependent effects of trans-resveratrol showed antiproliferative activity with an EC 50 value of 78.9 +/- 5.4 microM. Caspase-3 was activated in a dose-dependent manner after incubation for 24 h giving an EC 50 value of 276.1 +/- 1.7 microM. Apoptosis was also confirmed with microscopic observation of changes in membrane permeability and detection of DNA fragmentation. The activity of trans-resveratrol on the mitochondria apoptosis pathway was evidenced by the production of superoxide anions in the mitochondria of cells undergoing apoptosis. In conclusion, trans-resveratrol inhibits cell proliferation without cytotoxicity and induces apoptosis in HT-29. Results of the present study provide evidence demonstrating the antitumor effect of trans-resveratrol via a ROS-dependent apoptosis pathway in colorectal carcinoma.     

Molecular evidence for fat-tailed sheep domestication

The sheep is one of the most successful and widely spread domestic animals. Archaeological evidence traces the first domestic sheep back to the Near East region around 9,000 years ago. It is also known that soon after, the domesticated sheep started to flow out of the centre of origin and spread all over the ancient world following the expansion of agriculture. Throughout time, herders, nature elements and eventually some hybridization with different wild relatives produced a multitude of breeds. However, until the advent of the molecular genetics field, very little was known about the origins of most of those breeds. Two decades after the first genetic studies, we have gathered considerable information on the origins, phylogenetic relationships and patterns of genetic diversity of the sheep across the world. Indeed, the genetic studies confirmed the Near East region as the main centre of origin and also revealed other contributions from other regions. Specifically about the fat-tailed sheep, molecular genetics was also able to link their maternal origin to a specific group. So far, modern sheep have originated from five different maternal origins. Nonetheless, the technological advances of the DNA sequencing techniques are bringing more data that is showing the complexity of the domestication process.     

Discrimination of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> isolates from sweet and wild cherry using rep-PCR

Bacterial canker is one of the most important diseases of cherry (Prunus avium). This disease can be caused by two pathovars of Pseudomonas syringae: pv. morsprunorum and pv. syringae. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) was investigated as a method to distinguish pathovars, races and isolates of P. syringae from sweet and wild cherry. After amplification of total genomic DNA from 87 isolates using the REP (repetitive extragenic palindromic), ERIC (enterobacterial repetitive intergenic consensus) and BOX primers, followed by agarose gel electrophoresis, groups of isolates showed specific patterns of PCR products. Pseudomonas syringae pv. syringae isolates were highly variable. The differences amongst the fingerprints of P. syringae pv. morsprunorum race 1 isolates were small. The patterns of P. syringae pv. morsprunorum race 2 isolates were also very uniform, with one exception, and distinct from the race 1 isolates. rep-PCR is a rapid and simple method to identify isolates of the two races of P. syringae pv. morsprunorum; this method can also assist in the identification of P. syringae pv. syringae isolates, although it cannot replace inoculation on susceptible hosts such as cherry and lilac.     

Direct molecular detection of the pinewood nematode, <Emphasis Type="Italic">Bursaphelenchus xylophilus</Emphasis>, from pine wood,bark and insect vector

The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease. The international economic impact of the introduction of the PWN into new areas has highlighted the need for the development of accurate and reliable detection methods of B. xylophilus, which are essential to define aspects of its control and management. In the present study, a methodology was developed for the direct detection of PWN by conventional PCR assay, with a species specific set of primers based on PWN satellite DNA, using total DNA extracted directly from maritime pine, Pinus pinaster, wood and bark samples, and from the insect vector, Monochamus galloprovincialis. This methodology involves homogenisation of wood, bark and insects using liquid nitrogen, DNA extraction and one or two PCR amplification steps, which permit the rapid and direct detection of one single nematode present in 100 mg of wood and bark and in one entire insect without the preliminary steps of nematode extraction.