Growth and survival of juvenile spider crabs,Maja brachydactyla (Balss, 1922), fed with fresh or frozen mussels

The effects of diet freezing on the growth, survival and biochemical composition of the diets and juvenile spider crabs (Maja brachydactyla) were studied. Fresh and frozen (at ?20 °C for 21 days) mussels, Mytilus edulis, were used as food. Two experiments were conducted and in each, spider crabs were placed in individual trays. During experiment I, 40 juvenile spider crabs (2 months old) were used. Twenty animals (9 ± 2 mg) were fed fresh mussels, and 20 animals (8 ± 2 mg) were fed frozen mussels. Spider crabs fed fresh mussels grew larger than the ones fed frozen mussels (304.0 ± 118.0 and 70.0 ± 40.1 mg respectively). During experiment II, 16 juvenile spider crabs (5 months old) were used. Eight animals (3.4 ± 0.8 g) were fed fresh mussel and eight animals (4.1 ± 1.3 g) were fed frozen mussel. Spider crabs fed with fresh mussels were larger than the ones fed with frozen mussels (92.5 ± 41.7 and 41.5 ± 17.7 g respectively). There were no significant differences in the protein, amino acids and fatty acid composition between fresh and frozen mussels. The freezing procedure makes mussels less adequate for the culture of 2‐month‐old early juveniles of M. brachydactyla up to 5 months, although they promoted acceptable growth and good survival in older animals (>5 months old).     

Effect of diet on the lipid composition of the commercial clam Donax trunculus (Mollusca: bivalvia): sex‐related differences

This paper describes the lipid composition of the commercial bivalve Donax trunculus and the differences originated when the animals were fed with two phytoplankton species (Tetraselmis suecica and Chaetoceros sp.) in a hatchery. We also analysed sex‐related differences in lipid classes and fatty acid profile. Total lipids were higher in females than in males. Triglycerides and phospholipids were the major lipid components, and the former dominated in females and the latter in males. The main fatty acids in both sexes were 16:0, 20:5n‐3 (eicosapentaenoic acid) and 22:6n‐3 (docosahexaenoic acid). Females showed higher percentages of saturated and monounsaturated fatty acids and lower levels of polyunsaturated fatty acids than males. Significant differences in total lipid, lipid classes and fatty acid profiles were also found due to diet. Docosahexaenoic acid decreased and total lipids, free fatty acids, arachidonic acid and EPA increased in both sexes. Despite these differences, the condition of the species was maintained and the broodstock even maturated.     

Kinetics of Lead Bioaccumulation from a Hydroponic Medium by Aquatic Macrophytes Pistia stratiotes

The goal of this work was to study quantitatively lead bioaccumulation from a lead-doped nutrient medium by using a living aquatic macrophytes Pistia stratiotes. Several sets of aquatic plants with approximately 30 g weight were grown in greenhouse conditions and in hydroponic solutions supplied with a non-toxic Pb²⁺ concentration. The synchrotron radiation total X-ray fluorescence spectrometry was used to determine the metal concentrations in dry plants and hydroponic media as a function of time. Four different non-structural bioaccumulation models were applied to describe the process dynamics and to estimate the accumulated lead maximum capacity and rate constants. According to the experimental data, both biosorption and bioaccumulation mechanisms can be considered. Due to the low desorption rate constant, the experimental data were well described by the irreversible kinetic model. The results concerning modeling of living macrophytes’ metal bioaccumulation kinetics can be used to predict the heavy metal removal dynamics from wastewaters in artificial wetlands.     

Mic1-3 Knockout Toxoplasma gondii is a good candidate for a vaccine against T. gondii-induced abortion in sheep

This study assessed the effectiveness of a mutant strain of Toxoplasma gondii (RH strain) lacking the mic1 and mic3 genes (Mic1-3KO) against Toxoplasma abortion in sheep. Ewes were inoculated subcutaneously with 10⁵ Mic1-3KO tachyzoïtes in three independent experiments. Following vaccination, Mic1-3KO induced a mild febrile response and serum IgG antibodies, which persisted throughout the experiments. Tissue cysts formed in the sheep, but were not, under our experimental conditions, infectious when given orally. Ewes were mated two months after vaccination and were orally challenged with the PRU strain of T. gondii at mid-gestation (400 oocysts in Experiments 1 and 2; 100 oocysts in Experiment 3). Challenge of vaccinated pregnant ewes resulted in a slight febrile response, whereas unvaccinated ewes developed a more severe, characteristic febrile response of longer duration. After challenge, all unvaccinated ewes aborted whereas 62%, 91% and 64% (Experiments 1, 2 and 3 respectively) of the lambs from vaccinated ewes were viable, with no clinical signs of infection. Mic1-3KO was as effective as S48, the strain used as a live vaccine for sheep (Toxovax^®). A dose of 10⁵ Mic1-3KO tachyzoites was sufficient to induce protection (versus a dose of 2 × 10⁶). Both subcutaneous and intraperitoneal injections were effective. Moreover, preliminary results showed the potential of Mic1-3KO to reduce the development of tissue cysts in lambs born to vaccinated ewes. This study demonstrates that Mic1-3KO is a potent vaccine candidate.     

Plasticity of animal genome architecture unmasked by rapid evolution of a pelagic tunicate

Genomes of animals as different as sponges and humans show conservation of global architecture. Here we show that multiple genomic features including transposon diversity, developmental gene repertoire, physical gene order, and intron-exon organization are shattered in the tunicate Oikopleura, belonging to the sister group of vertebrates and retaining chordate morphology. Ancestral architecture of animal genomes can be deeply modified and may therefore be largely nonadaptive. This rapidly evolving animal lineage thus offers unique perspectives on the level of genome plasticity. It also illuminates issues as fundamental as the mechanisms of intron gain.     

Coloring plastinated specimens

In the early days of plastination, plastinate Color was the usual grey/brown familiar to formalin‐fixed biological specimens. Initially, trials with Kaiserling's, Klotz, Jore's and McCormick's fixative solutions were disappointing. Vascular injections with Colored epoxy were a great breakthrough in the 1980s. Biodur AC10^® stain was the first stain of note to be applied to gross specimens to be plastinated and was applied in the last acetone bath. As plastination became more popular, specimen Color became an important and necessary aspect. Reactivation of the normal Color of red blood cells within a formalin‐fixed specimen was introduced as a mechanism to restore Color to plastinated specimens. Painting of plastinated vessels was tried with some success, and finally, a superior new proprietary type of silicone coloration was developed. More recently, a versatile red pigment stain was developed. All of these have added aesthetically to the plastination processes and will certainly be a reality in the years to come. The various methodologies to Color plastinates are presented. Time will tell how effective these may or may not be.     

Subpolar gyre and temperature drive boreal fish abundance in Greenland waters

As result of ocean warming, marine boreal species have shifted their distribution poleward, with increases in abundance at higher latitudes, and declines in abundance at lower latitudes. A key to predict future changes in fish communities is to understand how fish stocks respond to climate variability. Scattered field observations in the first half of the 20th century suggested that boreal fish may coherently invade Greenland waters when temperatures rise, but this hypothesis has remained untested. Therefore, we studied how local temperature variability and the dynamics of the subpolar gyre, a large‐scale driver of oceanic conditions in the North Atlantic, affect abundance of boreal fishes in a region that sharply defines their lower thermal boundary. We analysed information from demersal trawl surveys from 1981 to 2017, for species distributed from shallow shelf to depths of 1,500 m, collected at over 10,000 stations along ~3,000 km of Greenland. Our results show that local temperature and variability of Labrador and Irminger Sea water in the subpolar gyre region drive interdecadal variability of boreal fish abundance in Greenland waters. Although temperature fluctuations were higher in shallow than deep regions, fish abundance changed as quickly in great depths as in shallow depths. This link between physics and biology provides an opportunity for prediction of future trends, which is of utility in Greenland, where fisheries constitute more than 90% of the national export value.     

Aggregation of casein micelles by interactions with chitosans: a study by Monte Carlo simulations

Recently, it was found that the addition of chitosan, a cationic polymer, to whole or skim milk produces the destabilization and coagulation of casein micelles which takes place without modifications in the milk pH or in the stability of most of the whey proteins. In the present work, Monte Carlo simulations are employed to show that the phase separation of casein micelles induced by chitosan can be explained by a depletion mechanism, where an effective attraction between the casein micelles is induced by the presence of chitosan molecules. This interaction is described on the basis of Vrij's model, where the depletion of polymer from the gap between neighboring casein micelles originates an effective attractive interaction that leads to a phase transition. This model, that considers volume restriction effects, accounts for several qualitative and even quantitative aspects of the experimental data for the coagulation of casein through chitosan addition.     

Vitamin A deficiency and child mortality in Mozambique

BACKGROUND: In areas where vitamin A deficiency (VAD) is prevalent, vitamin A repletion reduces child mortality by 23% on average. OBJECTIVES: To estimate the potential child survival benefits of policies and programmes aimed at controlling VAD in Mozambique, and to make policy and programme recommendations. METHODS: The potential contribution of VAD to child mortality in Mozambique was estimated by combining the observed VAD prevalence in the under-5s (71.2%), the measured child mortality effects of VAD (risk of death in children with VAD=1.75 times higher than in children without VAD) and the observed under-5 mortality rate in the country (210 per 1000 live births). RESULTS: In Mozambique, an estimated 2.3 million children below the age of 5 years are vitamin-A-deficient. In the absence of appropriate policy and programme action, VAD will be the attributable cause of over 30,000 deaths annually in the under-5s. This represents 34.8% of all-cause mortality in this age group. DISCUSSION: Vitamin A supplementation (VAS) has been adopted as a short- to medium-term strategy to control VAD in children, and is integrated into routine child health services. However, the last VAS coverage survey showed that only 46% of children received a vitamin A supplement in the 6 months preceding the survey. If VAS coverage is to increase significantly in the foreseeable future, four areas appear to be of paramount importance: (1) reduce missed opportunities for VAS such as visits of sick children to child health services and community outreach activities; (2) take advantage of all potential opportunities for accelerating VAS coverage, such as additional vaccination campaigns and emergency response activities; (3) strengthen health workers' training, supervision and monitoring skills; and (4) increase community demand for VAS of children. Biannual VAS, as the primary component of an integrated strategy for VAD control in children, has the promise to be among the most cost-effective/high-impact child survival interventions in Mozambique.     

Reversible precipitation of casein micelles with a cationic hydroxyethylcellulose

The cationic hydroxyethylcellulose Polyquaternium 10 (PQ10) was found to produce a dose-dependent destabilization of casein micelles from whole or skim milk without affecting the stability of most of the whey proteins. The anionic phosphate residues on caseins were not determinant in the observed interaction since the destabilization was also observed with dephosphorylated caseins to the same extent. However, the precipitation process was completely inhibited by rising NaCl concentration, indicating an important role of electrostatic interactions. Furthermore, the addition of 150 mM NaCl solubilized preformed PQ10-casein complexes, rendering a stable casein suspension without a disruption of the internal micellar structure as determined by dynamic light scattering. This casein preparation was found to contain most of the Ca2+ and only 10% of the lactose originally present in milk and remained as a stable suspension for at least 4 months at 4 degrees C. The final concentration of PQ10 determined both the size of the casein-polymer aggregates and the amount of milkfat that coprecipitates. The presence of PQ10 in the aggregates did not inhibit the activity of rennet or gastrointestinal proteases and lipases, nor did it affect the growth of several fermentative bacteria. The cationic cellulose PQ10 may cause a reversible electrostatic precipitation of casein micelles without disrupting their internal structure. The reversibility of the interaction described opens the possibility of using this cationic polysaccharide to concentrate and resuspend casein micelles from whole or skim milk in the production of new fiber-enriched lactose-reduced calcium-caseinate dairy products.