Anhydrous goat's milk fat: thermal and structural behaviors studied by coupled differential scanning calorimetry and X-ray diffraction. 2. Influence of cooling rate

Crystallization and melting properties of triacylglycerols (TGs) in anhydrous goat's milk fat (AGMF) are investigated by X-ray diffraction as a function of temperature (XRDT) coupled with high-sensitivity differential scanning calorimetry (DSC), using synchrotron radiation and Microcalix. The polymorphic behavior of AGMF was monitored by varying the cooling rates between 5 and 1 degrees C/min from 45 to -20 degrees C with their subsequent melting at 1 degrees C/min. Quenching of AGMF at -20 degrees C was also examined to determine the metastable polymorphic form of AGMF. At intermediate cooling rates, TGs in AGMF crystallize, from about 18 degrees C in two different lamellar structures with triple chain length 3Lalpha stacking of 72 A and a double chain length 2Lalpha stacking of 48 A, which are correlated to two overlapped exothermic peaks recorded by DSC. A reversible transition sub alpha <--> alpha was observed. Subsequent heating at 1 degrees C/min shows numerous structural rearrangements before final melting. At fast cooling of AGMF (5 degrees C/min), similar unstable crystalline varieties are formed while three endotherms are recorded. Several new unstable lamellar structures are observed after quenching. All of these data are compared to those previously reported at slow cooling (0.1 degrees C/min) showing a relative stability of the structures formed. In spite of general similitude, the thermal and structural behavior of the goat's milk is more complex than that of the cow's milk.     

Biochemical indices (RNA/DNA ratio and protein content) in studying the nutritional status of Ruditapes decussatus (Linnaeus 1758) juveniles

In this work, we investigated the nutritional status of Ruditapes decussatus juveniles under different rearing conditions, using biochemical indices (RNA/DNA ratio and protein content) and the linear instantaneous growth rate (IGR). Two experiments were conducted to study the effect of starvation, addition of substrate (sand) as rearing support and diet composition on somatic growth and biochemical indices. Results show that biochemical indices of fed juveniles were significantly (P<0.05) higher. Highest RNA/DNA values and protein content were recorded in fed juveniles reared with substrate (P<0.05); conversely, lowest values were recorded in starved ones reared without substrate. In the second experiment, the highest RNA/DNA ratio was recorded in juveniles fed with control algal mixture composed of species commonly used in bivalve nurseries [Isochrysis galbana (clone T-Iso), Chaetoceros calcitrans and Tetraselmis suecica] and lowest in those fed with algal species isolated from Tunisian coasts. This confirms the usefulness of the RNA/DNA ratio and protein content in the clam's nutritional status evaluation. This assay is useful to provide information about the nutritional status and health of the clam in field conditions.     

Compatibility between <Emphasis Type="Italic">Calpurnia aurea</Emphasis> leaf extract,attraction aggregation,and attachment pheromone and entomopathogenic fungus <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> on viability,growth, and virulence of the pathogen

Metarhizium anisopliae sensu stricto (ss) (Metsch.) Sorok. isolate ICIPE 07 is being developed as biopesticide for the control of ticks. In addition, leaf extracts of Calpurnia aurea Benth, and the attraction aggregation and attachment pheromone (AAAP) are being used as ticks’ attractant. The three agents are being considered for use in combination in an autodissemination approach, whereby ticks that are attracted to semiochemicals are infected with the inoculum. Experiments were therefore conducted to evaluate in vitro the compatibility between C. aurea, AAAP, and the M. anisopliae on vegetative growth, conidial production, and spore viability. Calpurnia aurea leaf extract was compatible with the fungus at all the concentrations tested, whereas AAAP inhibited all the fungal growth parameters. The virulence of M. anisopliae formulated in emulsifiable extracts of C. aurea was also tested against different developmental stages of Rhipicephalus appendiculatus in laboratory bioassays. No significant differences in virulence were observed between M. anisopliae applied alone and M. anisopliae formulated in different concentrations of C. aurea leaf extracts. These results suggest that C. aurea leaf extracts is compatible with M. anisopliae and could be mixed together for “spot-spray” treatments as low-cost and environmental-friendly technology to control ticks in grazing field, while AAAP should be used separately.     

Variation in chemical composition and biological activities of two species of Opuntia flowers at four stages of flowering

The chemical composition of hexane extracts from flowers belonging to two species of prickly pear, Opuntia ficus-indica (L.) Miller and Opuntia stricta (Haw.) Haworth has been studied by gas chromatography-mass spectrometry in four developmental stages of flower: vegetative, initial flowering, full flowering, and post-flowering stages. Remarkable differences were noted between the flowers’ compositions. The main compounds were carboxylic acid (28-97%), terpenes (0.2-57%), esters (0.2-27%), and alcohols (<1.8%).The study of the biological activities showed that extracts were active in vitro towards four bacteria and two fungal strains. It exhibited remarkable activity against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli.Antioxidant activity of the flowers extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method.Our findings demonstrate the interest of Opuntia flowers extract as a source of bioactive substances and its potential preservative use in food.     

Isolation, identification and dyeing studies of betanin on modified acrylic fabrics

Mature red fruits of Opuntia ficus-indica contain two soluble pigment, betanin and indicaxanthin. The optimal conditions for dye extraction were to mix 50 g of juice from cactus pears with 100 mL of acidified water as solvent for dye extraction. Two main dyes were purified from the pigment extract by chromatography and identified by UV-vis, HPLC and LC-MS techniques as indicaxanthin (15 mg per 100 g) and betanin (280 mg per 100 g). The effect of dye bath pH, salt concentration, dyeing time and temperature was studied. The optimal conditions for dyeing modified acrylic fabrics with betanin dye were carried out at 50 °C for 45 min at pH 5. Un-mordanted samples have good properties of water and washing fastness. Mordant CoSO₄ was found to give good light fastness (rating 5).     

An epidemiological study of cataracts in wild and farmed lumpfish (Cyclopterus lumpus L.) and the relation to nutrition

Twelve groups of farmed lumpfish and one of wild lumpfish were screened for cataract and sampled for fish muscle tissue, whole heart and both eye lenses to investigate possible relations between cataract and tissue free amino acid concentrations. Cataract prevalence ranged from 20% to 100%, with the highest average score of 7.3 (max 8) and incidences of severe cataract (>5) in all groups. Cataract could not be explained by suboptimal histidine concentrations in the feed. Neither muscle nor cardiac tissues had concentrations of free histidine compounds. The lumpfish lens contained N‐acetylhistidine (NAH), of which low concentrations were strongly related to cataract severity. However, no correlation between lens NAH and cataract severity was found in the present sample set. Wild lumpfish had higher levels compared to farmed lumpfish, suggesting that the farmed lumpfish may have been deficient in histidine or have a higher utilization of NAH due to osmotic problems. Thus, cataract in farmed lumpfish may be related to primary or secondary disturbed nutrient metabolism or malnutrition, shown by the high levels of specific amino acids in different tissues, which may cause osmotic imbalance and cataract development. This nutritional or environmental‐related welfare problem deserves further research.     

Metallothionein and metal levels in liver,gills and kidney of <Emphasis Type="Italic">Sparus aurata</Emphasis> exposed to sublethal doses of cadmium and copper

The levels of metallothionein (MT), a biomarker of metal exposure, and of Cd and Cu, known as MT inducers, were investigated in Sparus aurata intraperitoneally injected with 500 μg/kg of Cu and Cd for 2 days. MT and metal concentrations (Cd and Cu) were determined in liver, gills and kidney. MT levels were significantly increased in all investigated tissues, with the highest value in liver of Cu as Cd-treated fishes (3.56-fold and 3.3- fold, respectively). Metal concentrations were statistically different between all tissues. Highest metal concentrations were in the liver. The higher metal concentrations and MT induction levels support the main role of MT in metal homeostasis and detoxification.     

Effect of broomrape (Orobanche cumana Wallr.) on some agro-morphological and biochemical traits of Tunisian and some reference sunflower (Helianthus annuus L.) accessions

Journal of Plant Diseases and Protection - Orobanche cumana Wallr. is an important new problem for sunflower crop in Tunisia. Little information is available on the behavior of sunflower to O....     

Use of earthworms Eisenia andrei on the bioremediation of contaminated area in north of Tunisia and microbial soil enzymes as bioindicator of change on heavy metals speciation

Purpose

A better understanding is required of the potential of soil biota in controlling the availability and mobility of heavy metals and ascertaining their toxicity. The objectives of this work are to assess, first, the modification of heavy metal speciation induced by earthworms Eisenia andrei and, second, the consequence of this metal speciation change on soil enzyme activities as an easy bioindicator of stress.

Materials and methods

The experiment was conducted on six sites from Jebel Ressas Mines, which are characterized by a gradient heavy metal contamination (Pb, Zn, and Cd). Earthworms E. andrei were introduced in these six soils for 60 days. We had performed heavy metal speciation both in the presence and absence of worms. Modifications of activities of seven enzymes implicated in C, N, and P biochemical cycles were used as a bioindicator of metal stress. We had used the co-inertia statistical method to evaluate the correlation between change in heavy metal speciation induced by earthworms and the enzyme activities in soils.

Results and discussion

Our results suggested that earthworms modified the heavy metal dynamic and speciation. They decrease the amount of metal associated with the most available fraction, such as exchangeable one, and increase the amount of metal bound to the more stable fraction, like Mn and Fe oxide ones. On the same hand, enzyme activities increased in majority of the soils, following earthworm activity, but this effect is dependent on the amount of soil contamination. Moreover, the co-inertia results denote that change in heavy metal speciation significantly influences the soil enzyme activities in Jebel Ressas soils, especially β-glucosidase, urease, deshydrogenase, and fluorescein diacetate hydrolysis (FDA), and can be considered as bioindicators of metal toxicity and biological quality in the contaminated area.

Conclusions

By reducing the availability of heavy metals, the earthworms are useful in the bioremediation of heavy metal contaminated soils. Soil enzymes β- glucosidase, urease, deshydrogenase, and FDA can be used to assess the changes in metal speciation and can let us, therefore, predict if the soils are bioremediated.