Evaluation of protein aggregation in cooked meat

International audienceThe effect of meat cooking on protein aggregation was measured in pig M. Longissimus dorsi. Muscles were aged 4 days in air and then cooked at 100 degrees C for 10 or 30 min. Meat was ground in a KCl solution and the whole extract was delipidated with a mixture of butanol and di-isopropyl ether in a 40:60 v/v ratio. Protein aggregation induced by cooking was evaluated with a laser granulometer, which enabled reliable and reproducible characterisation of particle size distributions, and particle shape distributions using automated imaging techniques. Cooking significantly decreased the level of big particles, while the number of small particles remained stable. Cooking also affected the form and size of the particles. In order to better understand the mechanisms implicated in the aggregation process the level of protein oxidation and the protein surface hydrophobicity were evaluated in parallel with the granulometry measurements. Significant correlations were observed between the granulometry parameters and some of the protein oxidation indices. The protein surface hydrophobicity was also correlated with the granulometry parameters demonstrating the impact of thermal denaturation on the aggregation process

Comparison of the early axial musculoskeletal system between amniote and fish.

<p>Schematic frontal sections through trunk region of amniote (<b>A</b>) and fish embryos (<b>B</b>). (<b>A</b>) Amniote embryo. The sclerotome that derives from an important portion of the somite gives rise to chondroprogenitors surrounding axial structures (notochord and neural tube). Scleraxis expressing tendon progenitors originating from the dorsolateral edge of the early sclerotome lie between adjacent myotomes (adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091876#pone.0091876-Charvet2" target="_blank">[13]</a>). (<b>B</b>) Fish embryo (17dpf). The sclerotome that represents a reduced somite derivative gives rise to a limited number of chondroprogenitors that express osteoblast-specific factor2/periostin. Adjacent myotomes are separated by Scleraxis-expressing myoseptal cells. A dermomyotome (white and red vertical lines) at the surface of the myotome persists late during fish development and expresses high levels of <i>col1a1</i>, <i>col5a2</i> and <i>col12a1</i>.</p

Apparent movement of <i>col1a1</i> expressing cells suggests a sclerotomal origin of myoseptal cells.

<p>(<b>A</b>) Transverse section of a 13 dpf embryo. <i>Col1a1</i> staining is present in the ventrally located sclerotome cells (arrow). (<b>B</b>) Transverse section of a 14 dpf embryon. Labelled cells have migrated dorsally to surround the notochord (arrow). (<b>C</b>–<b>E</b>) Frontal section of trout embryo at the level of the notochord. (<b>C</b>) 14 dpf embryo. Labelled cells surround the notochord. (<b>D</b>) 15 dpf embryo. Some labelled cells occupy the medial aspect of the intermyotomal space. (<b>E</b>) 16 dpf embryo. The medial-lateral extent of the intermyotomal space contains labeled cells. (<b>C</b>′–<b>E</b>′) Merged images showing <i>col1a1</i> labelling and Hoechst nuclear staining, white arrows indicate the intermyotomal space. n: notochord; m: myotome. Scale bars in A and B, 50 μm; C, C′, D, D′, E and E′, 30 μm.</p

The intermyotomal space is colonized by fibroblast-like cells that do not express myogenic markers.

<p>(<b>A and B</b>) Semithin frontal sections through the trunk of an eyed stage (17 dpf) embryo with final number of somites and pigmented eyes. (<b>A</b>) Posterior tail. Myoseptal cells are visible in the medial half (arrows) of the space separating two somites. (<b>B</b>) Anterior tail. Myoseptal cells are visible throughout the medio-lateral extent of the intermyotomal space. (<b>C</b>) Pax 7 expression is restricted to cells forming the dermomyotome-like epithelium at the surface of the myotome. (<b>C′</b>) Merged image showing Pax7 labeling and Hoechst staining for nuclei visualisation. (<b>D</b>) Myogenin expression is observed in the primary myotome located below the dermomyotome-like (<b>D′</b>) Merged image showing myogenin labeling and Hoechst staining. mc: myoseptal cells, m: myotome, der: dermomyotome. Scale bars in A, B, C and D, 25 μm.</p

Expression of Scleraxis in myoseptal cells.

<p>Eyed stage (17dpf) embryo. (<b>A</b>–<b>B</b>) whole mount in situ hybridization. (<b>A</b>) Lateral view. (<b>B</b>) Dorsal view. Scleraxis is localised at the anterior and posterior myotome borders. (<b>C</b>–<b>F</b>) Serial frontal sections through the trunk of an eyed stage trout embryo. (<b>C</b>) A section at the dorsal neural tube level shows few labelled myoseptal cells medially in the intermyotomal space. (<b>D</b>) A section at the ventral neural tube level shows that labelled myoseptal cells are visible within the medial half of the intermyotomal space. (<b>E</b>) Sections at the level of the notochord and (<b>F</b>) ventral to the notochord show that labelled cells are present throughout the medio-lateral extent of the intermyotomal space. (<b>C</b>′–<b>F</b>′) Merged images showing Scleraxis labelling and Hoechst nuclear staining; there is no labelling in skeletogenic cells immediately adjacent to the neural tube and notochord. nt: neural tube; n: notochord, mc: myoseptal cell; sc: skeletogenic cells. Scale bars in A, 300 μm; B, 200 μm Scale bars in C, C′, D and D′, 25 μm; E, E′, F and F′, 40 μm.</p

Myoseptal cells express genes involved in extracellular matrix production and remodelling.

<p>(<b>A</b>–<b>D</b>) Frontal sections of eyed stage (17 dpf) embryos. Expression of (<b>A</b>) <i>col1a1</i>, (<b>B</b>) <i>col5a2</i>, (<b>C</b>) <i>col12a1</i> and (<b>D</b>) Angiopoietin-7 like. mc: myoseptal cell; sc: skeletogenic cells; m: myotome; n: notochord. Scale bars, 20 μm.</p

Collagen I is concentrated at the surface of the somites.

<p>(<b>A and B</b>) Frontal sections through the trunk of a 13 dpf trout embryo. (<b>A</b>) Posterior tail. Collagen I immunofluorescence localises to the anterior and posterior edges and at the lateral surface of the dermomyotome. (<b>B</b>) Anterior tail. Collagen I immunofluorescence is present along the space separating adjacent somites. der: dermomyotome. Scale bars in A and B, 15 μm.</p

Nurturing niche innovations by agrifood value chains in transition to agroecology. A qualitative analysis through eleven case studies in France

Résumé de la communication. Les autres pages du document présentent les thématiques des sessions de la conférence.International audienceThe agroecological transition of the French agrifood sector is an important challenge for sustainability. This sector is distinguished from others by specific features, including its structuring into 'vertical' value chains. These specificities need to be examined carefully, as they condition the way in which innovation niches can emerge and transform the sociotechnical regime. In this article, we study a variety of agrifood value chain initiatives in France engaged in sustainable practices that can be related to certain dimensions of agroecology. These initiatives are analysed through the prism of the "innovation functions" of Hekkert et al. (2007) to deepen the nurturing step of such value chain innovation niches. We added two functions: a function of governance and coordination and a function of network development. As outcomes, we highlight 1) the relative importance of the different innovation functions during the nurturing phase; and 2) the singularities of the agrifood sector in general and of agrifood value chain initiatives in particular, notably i) the role played by dominant regime actors, ii) the importance of market differentiation, iii) the importance of practices objectivation through certification, iv) the problem of consumer preferences uncertainty; and v) the strategies of inter-value chain connexions, which are key for the transition