Physical and chemical properties of sporopollenin exine particles

The chemical structure of sporopollenin was extensively reviewed, along with some considerations pertaining to its physical and biological properties. A comparative study is presented of extraction protocols to isolate exines from L. clavatum, in particular, but with extension to spores from other species, namely, Lycopodium spec., Ambrosia trifida, Aspergillus niger and Chlorella vulgaris. Physical aspects of the materials extracted were studied, including size (highlighting large and small types of commercial “Lycopodium”), wall thickness, mechanical resistance and density.Encapsulation of a wide variety of compounds in sporopollenin microcapsules was investigated using passive, vacuum, compression and centrifugation methods. Diverse products, with molecular weights ranging from less than 1kDa to 464kDa, were successfully encapsulated in exines, including both polar (e.g. dyes, proteins, carbohydrates and oligonucleotides) and non-polar products (e.g. oils and waxes). It was shown that a protein, alkaline phosphatase, does not lose its initial activity after it has been encapsulated in exines and subsequently released.Sporopollenin was found to grant oils protection against photooxidation triggered by UV light and the extinction coefficient of sporopollenin was determined (20,000-40,000m¯¹). Protective abilities offered by exines to oils against aerial oxidation, and refining effects of sporopollenin on rancid fats, were studied, completed by a preliminary investigation of sporopollenin’s redox characteristics. A flavour test on 20 volunteers showed that exines mask the taste of encapsulated cod liver oil up to a 1/1 (w/w) loading level.Sporopollenin was also used in solid-phase organic synthesis. It was established that the reaction of ammonia, primary aliphatic amines and aniline with sporopollenin formed an amide bond on a carboxylic group of the sporopollenin. A short diamine was attached to sporopollenin in order to construct a spacer arm by further reaction between the free amino end and succinic anhydride. Sporopollenin was derivatised with bromine and chlorine by addition to the unsaturated functional groups, substitution of the hydroxyl groups and chloromethylation of the aromatic rings. The attached halogen atoms were then successfully substituted by azide and thiols. The thiol availability to nucleophilic substitution and formation of disulphide bridges was assessed

Sporopollenin exine capsules (SpECs) derived from Lycopodium clavatum provide practical antioxidant properties by retarding rancidification of an ω-3 oil

In recent years the use of natural antioxidants in foodstuffs and personal care products has become increasingly important for consumers and therefore manufacturers. In this work, sporopollenin exine capsules (SpECs), extracted from spores of the common club moss Lycopodium clavatum L, have been shown to protect an ω-3 oil from oxidation caused by natural light or accelerated oxidation with UV irradiation. The mechanism of action has been shown to be principally by free radical quenching as opposed to light shielding, supported by evidence of similarity in levels of protection when the ratio of SpECs to oil was 0.2 % w/v compared with 50 % w/w. The antioxidant effect is not materially altered by the extraction process from the raw material and is clearly an inherent property of the sporopollenin contained in the spores of L. clavatum due to the accessible phenolic groups on the surface on the SpECs. These results provide promising evidence that SpECs could be useful as a bio-sourced antioxidant for protecting ω-3 oils and related oxidation-prone molecules

Physical and chemical properties of sporopollenin exine particles

The chemical structure of sporopollenin was extensively reviewed, along with some considerations pertaining to its physical and biological properties. A comparative study is presented of extraction protocols to isolate exines from L. clavatum, in particular, but with extension to spores from other species, namely, Lycopodium spec., Ambrosia trifida, Aspergillus niger and Chlorella vulgaris. Physical aspects of the materials extracted were studied, including size (highlighting large and small types of commercial “Lycopodium”), wall thickness, mechanical resistance and density. Encapsulation of a wide variety of compounds in sporopollenin microcapsules was investigated using passive, vacuum, compression and centrifugation methods. Diverse products, with molecular weights ranging from less than 1kDa to 464kDa, were successfully encapsulated in exines, including both polar (e.g. dyes, proteins, carbohydrates and oligonucleotides) and non-polar products (e.g. oils and waxes). It was shown that a protein, alkaline phosphatase, does not lose its initial activity after it has been encapsulated in exines and subsequently released. Sporopollenin was found to grant oils protection against photooxidation triggered by UV light and the extinction coefficient of sporopollenin was determined (20,000-40,000m¯¹). Protective abilities offered by exines to oils against aerial oxidation, and refining effects of sporopollenin on rancid fats, were studied, completed by a preliminary investigation of sporopollenin’s redox characteristics. A flavour test on 20 volunteers showed that exines mask the taste of encapsulated cod liver oil up to a 1/1 (w/w) loading level. Sporopollenin was also used in solid-phase organic synthesis. It was established that the reaction of ammonia, primary aliphatic amines and aniline with sporopollenin formed an amide bond on a carboxylic group of the sporopollenin. A short diamine was attached to sporopollenin in order to construct a spacer arm by further reaction between the free amino end and succinic anhydride. Sporopollenin was derivatised with bromine and chlorine by addition to the unsaturated functional groups, substitution of the hydroxyl groups and chloromethylation of the aromatic rings. The attached halogen atoms were then successfully substituted by azide and thiols. The thiol availability to nucleophilic substitution and formation of disulphide bridges was assessed

Type de prairie, changement climatique et pérennité de la production fourragère. Analyse à l’échelle des prairies et du système fourrager d’exploitations du Pays de la Déodatie (Vosges)

International audienceIn order to study the vulnerability of livestock farms to climate change in the Déodatie region, and thus their sustainability, the production of forage plots (permanent and temporary grasslands, silage maize) was simulated over the period 1989-2100 with the mechanistic model STICS (research version). The pedoclimatic characteristics and the type of vegetation of each plot were taken into account. Depending on the type of grassland and the climatic and technical scenarios used, production could change by -30 to +40 % by 2100 compared to 1989-2020. At the farm level, the result is a compensation that allows forage production to be maintained, or even increased in the case of intensification (increased fertilization and the proportion of corn). However, this result is associated with an increase in the level of risk in terms of forage and organization.Afin d’étudier la vulnérabilité des élevages du Pays de la Déodatie au changement climatique, et donc leur pérennité, la production de parcelles fourragères (prairies permanentes et temporaires, maïs ensilage) a été simulée sur la période 1989-2100 avec le modèle mécaniste STICS (version de recherche). Les caractéristiques pédoclimatiques et le type de végétation de chaque parcelle ont été pris en compte. Selon les types de prairies, les scénarios climatiques et techniques retenus, la production pourrait évoluer de -30 à +40% à l’horizon 2100 par rapport à 1989-2020. A l’échelle de l’exploitation on obtient une compensation qui permet un maintien de la production fourragère, voire une augmentation en cas d’intensification (accroissement de la fertilisation et de la proportion de maïs). Ce résultat est cependant associé à une augmentation du niveau de risque sur le plan fourrager et organisationnel

UV and visible light screening by individual sporopollenin exines derived from Lycopodium clavatum (club moss) and Ambrosia trifida (giant ragweed)

We have investigated the UV–visible light transmission of three types of micrometre-sized sporopollenin exine shells, two derived from Lycopodium clavatum (club moss) spores and one from Ambrosia trifida (giant ragweed) pollen. We have used spectrophotometer measurements of partial monolayers of exines and microscope absorbance imaging to derive the light transmission properties of individual exines. Measurements have been made for exines in air when light transmission losses are due to a combination of absorption, reflection and scattering processes and for exines dispersed in a liquid for which the refractive index (RI) is approximately equal to the RI of the exine such that reflection and scattering effects are negligible. Overall, it found that the light transmission of a single exine wall is approximately 50%. This value of the transmission is due mainly to light absorption, is similar for the three exines studied here and varies only slightly with light wavelength over the range 200–900 n

Access to a primary aminosporopollenin solid support from plant spores

Sporopollenin, which is a naturally occurring and highly resilient organic polymer constituting the external shell of spores and pollen grains, has been converted into a primary amine form with a loading of 0.58 +/- 0.04 mmol. g(-1) by reductive amination with ammonia and lithium aluminium hydride successively. The presence of the amine and precursor amide groups were established by combustion elemental analysis, ICP-OES, FTIR, solid-state NMR and reactivity of the primary amine group to salt formation and nucleophilic addition and substitution with phenyl isothiocyanate and benzene sulfonyl chloride, respectively. This relatively simple conversion has served to provide further information regarding the presence and reactivity of carboxylic acid functions on this relatively uncharted polymer and offers aminosporopollenin as a new material for potential solid-phase applications

MRI contrast agent delivery using spore capsules: controlled release in blood plasma

The exine coatings of spores can be used to encapsulate drug molecules. We have demonstrated that these microcapsules can be filled with a commercial gadolinium(III) MRI contrast agent (in this proof of concept study Gd-DTPA-BMA was used) which is slowly released in plasma due to enzymatic digestion of the capsule

Hitchhiking of deleterious alleles and the cost of adaptation in partially selfing species.

International audienceSelf-fertilization is generally seen to be disadvantageous in the long term. It increases genetic drift, which subsequently reduces polymorphism and the efficiency of selection, which also challenges adaptation. However, high selfing rates can increase the fixation probability of recessive beneficial mutations, but existing theory has generally not accounted for the effect of linked sites. Here, we analyze a model for the fixation probability of deleterious mutants that hitchhike with selective sweeps in diploid, partially selfing populations. Approximate analytical solutions show that, conditional on the sweep not being lost by drift, higher inbreeding rates increase the fixation probability of the deleterious allele, due to the resulting reduction in polymorphism and effective recombination. When extending the analysis to consider a distribution of deleterious alleles, as well as the average fitness increase after a sweep, we find that beneficial alleles generally need to be more recessive than the previously assumed dominance threshold (h < 1/2) for selfing to be beneficial from one-locus theory. Our results highlight that recombination aiding the efficiency of selection on multiple loci amplifies the fitness benefits of outcrossing over selfing, compared to results obtained from one-locus theory. This effect additionally increases the parameter range under which obligate outcrossing is beneficial over partial selfing

Pilocarpine-induced morphological changes.

<p>A) Reconstruction of silicon probe placement within a coronal section of the hippocampus. Scaled silicon probe outlines were superimposed on sections counterstained with DAPI. DiI tracks and multiunit activity guided probe alignment. B) No differences in the distance from stratum oriens in CA1 to the outer molecular layer of the inferior blade of the dentate gyrus were seen between control and pilocarpine animals. C) There was a significant decrease in the distance taken up by area CA1 in pilocarpine-treated animals measured from stratum oriens to the hippocampal fissure. D) Further analysis of CA1 demonstrated a significant decrease in stratum oriens and stratum radiatum in pilocarpine-treated animals, with no change to the pyramidal cell layer or stratum lacunosum-moleculare.</p