Effects of herbivory on the reproductive effort of 4 prairie perennials

Background  

Herbivory can affect every aspect of a plant's life. Damaged individuals may show decreased survivorship and reproductive output. Additionally, specific plant species (legumes) and tissues (flowers) are often selectively targeted by herbivores, like deer. These types of herbivory influence a plant's growth and abundance. The objective of this study was to identify the effects of leaf and meristem removal (simulated herbivory within an exclosure) on fruit and flower production in four species (Rhus glabra, Rosa arkansana, Lathyrus venosus, and Phlox pilosa) which are known targets of deer herbivory.     

Mineral Composition of the Palms Leaflets of the Date Palm

This work was realized in two Tunisian continental palm plantations (Deglet Nour). It aimed at studying the mineral composition of date palms' leaflets to base recommendations for foliar diagnosis on.

At pollination, three palms per palm tree were taken at the median position, the lower green palm, and the last open palm. Leaflets were analyzed on the entire palm split into 4 zones. A broad variation of the palm portions leaflets' mineral composition is shown. The median zone leaflet nitrogen (N) and magnesium (Mg) contents were the highest for all of the palm positions. A similar nitrogen and magnesium determination was noticed along each palm.

The highest calcium (Ca) content was at the base of the youngest palm and at the apex of the oldest palm; phosphorus (P) content was the reverse. The highest potassium (K) content was determined in the base palm leaflets.

For foliar diagnosis, median zone leaflet sampling of median palm at pollination is recommended.     

Numerical simulation of embedding strength of glued laminated timber for dowel-type fasteners

A non-linear material model is proposed to describe the timber behavior. Anisotropic elasto-plastic constitutive law with hardening according to Hill yield criterion was used for the compressive behavior. Brittle behavior in tension and shear was modeled using the modified Hill failure criterion. The material model was implemented in a finite element code to simulate embedding strength of glued laminated timber for dowel-type fasteners. Reasonable agreement is found between numerical simulations and experimental measurements.     

Efficacy of insect nets for cabbage production and pest management depending on the net removal frequency and microclimate

In Africa, synthetic pesticide applications are overly frequent and above labelled rates. We assessed the efficacy of an insect net physical control system on field cabbage (Brassica oleracea var. capitata) production in France and Benin. Various mesh sizes and netting removal frequencies were compared under contrasting climatic conditions. Studies under Mediterranean climatic conditions (spring season) compared two mesh sizes (0.73 mm and 1.6 mm). Studies under subequatorial climatic conditions (cool and hot seasons) tested nets of mesh size 0.4 mm and 0.9 mm used either as permanent cover, removed daily, or 3 days per week. The results showed that a fine mesh did not improve the netting efficacy against pests but had a major impact on the microclimate. In Mediterranean climatic conditions, the netting efficacy and beneficial microclimate improved crop yields. In subequatorial conditions, crop yields were lowest with permanent net protection due to high temperatures under the nets and poor aphid and Spodoptera littoralis control. Removing the nets 3 days per week was a good technical/economic trade-off, ensuring acceptable efficacy with minimal effects on the microclimate.     

Bioaccessibility of carotenoids and vitamin E from their main dietary sources

Vitamin E and carotenoids are fat-soluble microconstituents that may exert beneficial effects in humans, including protection against cancer, cardiovascular diseases, and age-related eye diseases. Their bioavailability is influenced by various factors including food matrix, formulation, and food processing. Since human studies are labor-intensive, time-consuming, and expensive, the in vitro model used in this study is increasingly being used to estimate bioaccessibility of these microconstituents. However, the ability of this model to predict bioavailability in a healthy human population has not yet been verified. The first aim of this study was to validate this model by comparing model-derived bioaccessibility data with (i) human-derived bioaccessibility data and (ii) published mean bioavailability data reported in studies involving healthy humans. The second aim was to use it to measure alpha- and gamma-tocopherol, beta-carotene, lycopene, and lutein bioaccessibility from their main dietary sources. Bioaccessibility as assessed with the in vitro model was well correlated with human-derived bioaccessibility values (r = 0.90, p < 0.05), as well as relative mean bioavailability values reported in healthy human groups (r = 0.98, p < 0.001). The bioaccessibility of carotenoids and vitamin E from the main dietary sources was highly variable, ranging from less than 0.1% (beta-carotene from raw tomato) to almost 100% (alpha-tocopherol from white bread). Bioaccessibility was dependent on (i) microconstituent species (lutein > beta-carotene and alpha-carotene > lycopene and alpha-tocopherol generally > gamma-tocopherol), (ii) food matrix, and (iii) food processing.     

In vitro mechanical evaluation of torsional loading in simulated canine tibiae for a novel hourglass-shaped interlocking nail with a self-tapping tapered locking design

OBJECTIVE: To describe a novel interlocking nail (ILN) and locking system and compare the torsional properties of constructs implanted with the novel ILN or a standard 8-mm ILN (ILN8) by use of a gap-fracture model. SAMPLE POPULATION: 8 synthetic specimens modeled from canine tibiae. PROCEDURES: An hourglass-shaped ILN featuring a tapered locking mechanism was designed. A synthetic bone model was custom-made to represent canine tibiae with a 50-mm comminuted diaphyseal fracture. Specimens were repaired by use of a novel ILN or an ILN8 with screws. Specimens were loaded for torsional measurements. Construct compliance and angular deformation were compared. RESULTS: Compliance of the ILN8 was significantly smaller than that of the novel ILN. Mean +/- SD maximum angular deformation of the ILN8 construct (23.12 +/- 0.65 degrees) was significantly greater, compared with that of the novel ILN construct (9.45 +/- 0.22 degrees). Mean construct slack for the ILN8 group was 15.15 +/- 0.63 degrees, whereas no slack was detected for the novel ILN construct. Mean angular deformation for the ILN8 construct once slack was overcome was significantly less, compared with that of the novel ILN construct. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study suggests that engineering of the locking mechanism enabled the novel hourglass-shaped ILN system to eliminate torsional instability associated with the use of current ILNs. Considering the potential deleterious effect of torsional deformation on bone healing, the novel ILN may represent a biomechanically more effective fixation method, compared with current ILNs, for the treatment of comminuted diaphyseal fractures.     

Interactions between TGFβ1 and cyclic strain in modulation of myofibroblastic differentiation of canine mitral valve interstitial cells in 3D culture

ObjectivesThe mechanisms of myxomatous valve degeneration (MVD) are poorly understood. Transforming growth factor-beta1 (TGFβ1) induces myofibroblastic activation in mitral valve interstitial cells (MVIC) in static 2D culture, but the roles of more physiological 3D matrix and cyclic mechanical strain are unclear. In this paper, we test the hypothesis that cyclic strain and TGFβ1 interact to modify MVIC phenotype in 3D culture.Animals, materials and methodsMVIC were isolated from dogs with and without MVD and cultured for 7 days in type 1 collagen hydrogels with and without 5 ng/ml TGFβ1. MVIC with MVD were subjected to 15% cyclic equibiaxial strain with static cultures serving as controls. Myofibroblastic phenotype was assessed via 3D matrix compaction, cell morphology, and expression of myofibroblastic (TGFβ3, alpha-smooth muscle actin – αSMA) and fibroblastic (vimentin) markers.ResultsExogenous TGFβ1 increased matrix compaction by canine MVIC with and without MVD, which correlated with increased cell spreading and elongation. TGFβ1 increased αSMA and TGFβ3 gene expression, but not vimentin expression, in 15% cyclically stretched MVIC. Conversely, 15% cyclic strain significantly increased vimentin protein and gene expression, but not αSMA or TGFβ3. 15% cyclic strain however was unable to counteract the effects of TGFβ1 stimulation on MVIC.ConclusionsThese results suggest that TGFβ1 induces myofibroblastic differentiation (MVD phenotype) of canine MVIC in 3D culture, while 15% cyclic strain promotes a more fibroblastic phenotype. Mechanical and biochemical interactions likely regulate MVIC phenotype with dose dependence. 3D culture systems can systematically investigate these phenomena and identify their underlying molecular mechanisms.