Cell wall polysaccharides from chalkumra (Benincasa hispida) fruit. Part I. Isolation and characterization of pectins

Pectic polysaccharides were obtained from chalkumra (Benincasa hispida) fruit by sequential extraction with ammonium oxalate (fraction BOX), dilute acid (fraction BHCl), and cold dilute alkali (fraction BOH). The highest yield of polysaccharides was obtained with oxalate and HCl. BOX was enriched in partly methyl-esterified galacturonic acid, whereas BHCl and BOH contained mostly galactose. All of the extracts showed similar elution patterns in size exclusion chromatography although the intrinsic viscosities (eta) were different (132 +/- 6, 100 +/- 5, and 285 + 10 mL/g for BOX, BHCl, and BOH, respectively). From fractionation by anion exchange chromatography, homogalacturonan (as seen from sugar analysis and Fourier transform infrared spectrum) accounted for more than half of BOX and 11% of BHCl. Methylation analyses and hydrolysis of BHCl with endo-beta-(1-->4)-d-galactanase showed the presence of beta-(1-->4)-d-galactan. The neutral galactan represented more than 76% of BHCl and approximately 40% of BOH. The other polysaccharides were complex galactans in BOH and an acidic arabinan (<1%) in BOX and BHCl.     

Kinetics of formation and functional properties of conjugates prepared by dry-state incubation of beta-lactoglobulin/acacia gum electrostatic complexes

The formation of conjugates between beta-lactoglobulin and acacia gum based on electrostatic complexes formed at pH 4.2 was investigated upon dry-state incubation for up to 14 days at 60 degrees C and 79% relative humidity (RH). By means of SEC-HPLC and RP-HPLC, it was shown that the beta-lactoglobulin incubated alone was able to form polymers with molecular masses higher than 200 kDa until 50% of the initial monomeric protein disappeared after 14 days. In the presence of acacia gum at initial protein to polysaccharide weight mixing ratios of 2:1 and 1:2, only 35% of the initial beta-lactoglobulin monomers disappeared after 14 days. Using RP-HPLC, an apparent reaction order of 2 was found for the disappearance of monomeric beta-lactoglobulin both in the presence or absence of acacia gum. However, the reaction rate was faster in the absence of acacia gum. SDS-PAGE electrophoresis with silver staining confirmed the formation of beta-lactoglobulin/acacia gum conjugates. The solubility curves of the incubated beta-lactoglobulin showed a minimum around pH 4-5. By contrast, the minimum of solubility of the beta-lactoglobulin/acacia gum incubated mixtures shifted to lower pH values compared to initial mixtures. The conjugates exhibited higher foam capacity than the incubated protein as well as lower equilibrium air/water surface tension. Conjugation at ratio 1:2 led to increased interfacial viscosity (300 mN s m(-1) at 0.01 Hz) compared to beta-lactoglobulin alone (100 mN s m(-1) at 0.01 Hz), but similar interfacial elasticity (30-40 mN m(-1)). The foam capacity of the conjugates was significantly higher than that of the incubated beta-lactoglobulin as well as foam expansion and drainage time, especially at pH 5.3, i.e., higher than the pH of formation of the conjugates.     

Edible arabinoxylan-based films. 1. Effects of lipid type on water vapor permeability,film structure,and other physical characteristics

Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was observed in OK35-AX emulsion films. Contact angles of water comparable to those observed for LDPE films (>90 degrees ) are measured on the OK35-AX film surface. Finally, only triolein-AX emulsion films had elongation higher than films without lipid. These results suggest that OK35 enhances functional properties of AX-based films and should be retained for further research.     

Ecological effects of a major oil spill on panamanian coastal marine communities

In 1986 more than 8 million liters of crude oil spilled into a complex region of mangroves, seagrasses, and coral reefs just east of the Caribbean entrance to the Panama Canal. This was the largest recorded spill into coastal habitats in the tropical Americas. Many population of plants and animals in both oiled and unoiled sites had been studied previously, thereby providing an unprecedented measure of ecological variation before the spill. Documenation of the spread of oil and its biological begun immediately. Intertidal mangroves, algae, and associated invertebrates were covered by oil and died soon after. More surprisingly, there was also extensive mortality of shallow subtidal reef corals and infauna of seagrass beds. After 1.5 years only some organisms in areas exposed to the open sea have recovered.     

Cation-ratio and accelerator radiocarbon dating of rock varnish on mojave artifacts and landforms

The first accelerator radiocarbon dates of rock varnishes are reported along with potassium/argon ages of lava flows and conventional radiocarbon dates of pluvial lake shorelines, in an empirical calibration of rock varnish K(+) + Ca(2+)/Ti(4+) ratios with age in the Mojave Desert, eastern California. This calibration was used to determine the cation-ratio dates of 167 artifacts. Although cation-ratio dating is an experimental method, some dates suggest human occupation of the Mojave Desert in the late Pleistocene.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Identification,pathogenicity and community dynamics of fungi and oomycetes associated with pea root rot in northern France

The pea root rot complex is a major concern for green pea production worldwide. This study aimed at characterizing its composition and dynamics throughout a cropping season in northern France. To this end, fungi and oomycetes were isolated from green pea plant roots with symptoms sampled at the flowering stage in 22 fields in 2017, and at the pea emergence, elongation and flowering stages in two fields in 2018. Out of 646 isolates collected, 317 were identified using molecular markers. Fusarium oxysporum, F. solani and F. redolens were highly predominant. Pathogenicity tests separated the isolates into four aggressiveness groups. F. solani isolates were the most aggressive. Phylogenetic analysis of their TEF1 sequences showed that they mainly belonged to the F. pisi lineage, and that F. oxysporum isolates were genetically close to isolates from the UK that did not belong to the forma specialis pisi. In addition, several Clonostachys rhizophaga isolates are reported for the first time to cause pea root rot. The oomycetes were rarely found and were represented by a few Pythium spp. isolates. Lastly, this study shows that the fungal and oomycete communities associated with pea root rot change during the cropping season. The level of dissimilarity of the root-rot-associated communities decreased throughout the cropping season towards a more similar composition at the flowering stage, dominated by F. solani, F. oxysporum and F. redolens. The proportion of nonpathogenic to weakly pathogenic isolates decreased progressively during the growing season in favour of moderately to highly pathogenic isolates.     

Serum uric acid concentrations in horses heterozygous for combined immunodeficiency

Serum uric acid concentrations were determined in horses known to be carriers of combined immunodeficiency gene(s) and in presumed noncarrier horses. Uric acid concentrations were significantly higher (P less than 0.005) in carrier horses than in presumed noncarrier horses. However, there was some overlap in serum uric acid concentrations between carrier and presumed noncarrier horses.