Enhancing rotifer Brachionus calyciflorus population growth with commercial probiotics

The effect of a commercial probiotic (NanoCrusta, Altacrusta, Mexico City, Mexico) on the growth performance of Brachionus calyciflorus Pallas, 1766, was evaluated. In a first approach, probiotics were supplied in four densities (2.0 × 10³, 1.1 × 10⁵, 2.1 × 10⁵ and 2.1 × 10⁶ cells/ml), alone and in combination with Chlorella vulgaris (1 × 10⁶ cells/ml). The test rotifer did not grow on the probiotic alone. However, when probiotics + C. vulgaris were added, the maximum densities (D_max; ind/ml) and population growth rates (r) observed were higher. In the second experiment, probiotics were supplied at five higher densities (2.1 × 10⁶, 4.2 × 10⁶, 8.5 × 10⁶, 1.7 × 10⁷ and 3.4 × 10⁷ cells/ml) with C. vulgaris and a control treatment with only C. vulgaris (probiotic‐free). Treatments supplied with probiotics between 2.1 × 10⁶ and 1.7 × 10⁷ cells/ml showed significantly higher D_max and r than the control treatment. The results showed a positive effect of probiotic bacteria when supplied with C. vulgaris. The best outcome showed a D_max 2.16 times and an r 1.63 times higher than the density of the control treatment. Growth rates were higher in the treatments with probiotics compared to the control. We conclude that application of NanoCrusta is feasible to improve B. calyciflorus production, but the effects need to be tested in larger scales.     

Disodium-fosfomycin pharmacokinetics and bioavailability in post weaning piglets

Disodium-fosfomycin pharmacokinetics has been studied in different species after oral, intravenous, intramuscular and subcutaneous administration. At present there are neither documented clinical experiences of the use of fosfomycin in pigs nor any published studies in weaning piglets, although it is a period of high incidence of infectious diseases. The pharmacokinetics and the bioavailability of sodium fosfomycin were studied in post weaning piglets after intravenous and intramuscular administration of 15 mg/kg of body weight. Plasma concentrations were measured by a high-performance liquid ms/ms. After IV administration the area under the fosfomycin concentration:time curve in plasma was AUC_(0–12) of 120.00 ± 23.12 μg h/ml and the volume of distribution (Vd) of 273.00 ± 40.70 ml/kg. The elimination was rapid with a plasma clearance of 131.50 ± 30.07 ml/kg/h and a T_1/2 of 1.54 ± 0.40 h. Peak serum concentration (C_max), T_max, AUC_(0–12) and bioavailability for the IM administration were 43.00 ± 4.10 μg/ml, 0.75 ± 0.00 h, 99.00 ± 0.70 μg h/ml and 85.5 ± 9.90% respectively. Different authors have determined a minimum inhibitory concentration (MIC₉₀) ranging from 0.25 μg/ml for Streptococcus sp. and 0.5 μg/ml for Escherichia coli. Considering the above, and according to the values of plasma concentration vs time profiles observed in this study, effective plasma concentrations of fosfomycin for sensitive bacteria can be obtained following IV and IM administration of 15 mg/kg in piglets.     

Drought-induced oxidative stress in Canarian laurel forest tree species growing under controlled conditions

We studied photoprotection and antioxidative protection in the three major species of the Canarian laurel forest (Laurus azorica (Seub.) Franco, Persea indica (L.) K. Spreng and Myrica faya Aiton). Trees were exposed to drought under controlled conditions by withholding water until leaf relative water content (RWC) reached 50-55%. Drought reduced photosynthetic rate (P(N)) and was associated with decreased quantum yield of photosystem II (PSII) electron transport and increased non-photochemical quenching (NPQ) in L. azorica and M. faya, but did not increase NPQ in P. indica. Drought-treated trees of L. azorica had the highest de-epoxidation state (DPS) of the xanthophyll cycle and the highest zeaxanthin (Z) concentration, suggesting that this species had more effective photoprotective mechanisms than M. faya and P. indica. Moreover, beta-carotene remained unaltered in L. azorica trees during drought, suggesting that the chloroplasts of this species are better protected against oxidative stress than those of M. faya and P. indica. Increased antioxidation by ascorbate peroxidase, superoxide dismutase and glutathione reductase in L. azorica removed activated oxygen species (AOS) generated during drought treatment. Although M. faya was able to increase its energy dissipation rate by forming Z and thus increasing the DPS of the xanthophyll cycle, it did not respond to drought-induced oxidative stress with the result that beta-carotene degradation occurred. Persea indica did not activate an energy dissipation mechanism in response to drought treatment, hence formation of AOS was likely high in the drought-treated trees. In general, L. azorica was most resistant and P. indica most sensitive to photoinhibition and oxidative stress during drought.     

The mutagenesis of a type IV secretion system locus of Piscirickettsia salmonis leads to the attenuation of the pathogen in Atlantic salmon,Salmo salar

Piscirickettsiosis is a threatening infectious disease for the salmon industry, due to it being responsible for significant economic losses. The control of outbreaks also poses considerable environmental challenges. Despite Piscirickettsia salmonis having been discovered as the aetiological agent of the disease more than 25 years ago, its pathogenicity remains poorly understood. Among virulence factors identified so far, type four secretion systems (T4SS) seem to play a key role during the infection caused by the bacterium. We report here the genetic manipulation of P. salmonis by means of the transference of plasmid DNA in mating assays. An insertion cassette was engineered for targeting the icmB gene, which encodes a putative T4SS‐ATPase and is carried by one of the chromosomal T4SS clusters found within the genome of P. salmonis PM15972A1, a virulent representative of the EM‐90‐like strain. The molecular characterization of the resulting mutant strain demonstrated that the insertion interrupted the target gene. Further in vitro testing of the icmB mutant showed a dramatic drop in infectivity as tested in CHSE‐214 cells, which is in agreement with its attenuated behaviour observed in vivo. Altogether, our results demonstrate that, similar to other facultative intracellular pathogens, P. salmonis’ virulence relies on an intact T4SS.     

Development of a bioacoustic sensor for the early detection of Red Palm Weevil (Rhynchophorus ferrugineus Olivier)

The Red Palm Weevil (Rhynchophorus ferrugineus Olivier) is one of the worst pests for palms, since it can completely destroy the plant. Its early detection is very difficult and when the action of the pest is discovered, normally it is too late for recovering the plant. Bioacoustic sensors provide a good alternative for early detection of this pest because larvae activity is audible while they excavate tunnels to feed. This work describes the different stages for the development of an original electronic device based on acoustic sensors for early detection of Red Palm Weevil larvae in the interior of palms. This device is based on characteristic frequencies possibly related to their feeding activity. The performed tests have demonstrated that is possible to detect two week old larvae activity studying the sound intensity around 2250 Hz in palms infested only with 5 individuals under controlled environmental conditions. The activity of other insects artificially situated in the interior of palms did not affect the response of the device, possibly because they produce different frequencies (in the range 5–7 kHz). Future work will be aimed at assessing the infestation levels.     

Study of some physicochemical and functional properties of quinoa (chenopodium quinoa willd) protein isolates

The amino acid composition and the physicochemical and functional properties of quinoa protein isolates were evaluated. Protein isolates were prepared from quinoa seed by alkaline solubilization (at pH 9, called Q9, and at pH 11, called Q11) followed by isoelectric precipitation and spray drying. Q9 and Q11 had high levels of essential amino acids, with high levels of lysine. Both isolates showed similar patterns in native/SDS-PAGE and SEM. The pH effect on fluorescence measurements showed decreasing fluorescence intensity and a shift in the maximum of emission of both isolates. Q9 showed an endotherm with a denaturation temperature of 98.1 degrees C and a denaturation enthalpy of 12.7 J/g, while Q11 showed no endotherm. The protein solubility of Q11 was lower than that of Q9 at pH above 5.0 but similar at the pH range 3.0-4.0. The water holding capacity (WHC) was similar in both isolates and was not affected by pH. The water imbibing capacity (WIC) was double for Q11 (3.5 mL of water/g isolate). Analysis of DSC, fluorescence, and solubility data suggests that there is apparently denaturation due to pH. Some differences were found that could be attributed to the extreme pH treatments in protein isolates and the nature of quinoa proteins. Q9 and Q11 can be used as a valuable source of nutrition for infants and children. Q9 may be used as an ingredient in nutritive beverages, and Q11 may be used as an ingredient in sauces, sausages, and soups.     

Local and remote physical processes driving variability of the planktonic system in the Juan Fernández Archipelago: A multidisciplinary framework providing conservation insights

1. The Juan Fernandez Ridge, a vulnerable marine ecosystem located far off the coast of central Chile and formed by several seamounts, guyots and three islands (Robinson Crusoe, Santa Clara and Alejandro Selkirk), has recently been declared a Coastal Marine Protected Area of Multiple Uses with several National Parks embedded in it.
2. Recent studies have highlighted the influence of remote and local oceanographic structures on the hydrographic dynamics of this ridge. However, there is still a gap in understanding how they affect the structure and dynamics of the surrounding insular planktonic communities.
3. A hydroacoustic and oceanographic survey was conducted during the austral spring (October 2016), including hydrographic and zooplankton sampling around Robinson Crusoe Island. Oceanographic features were identified and tracked using satellite data (chlorophyll-a (Chl-a) and sea surface temperature) and modelling results.
4. Two events of Chl-a increase relative to a threshold (>0.45 mg m⁻³) were forced by different physical processes, both affecting the western side of Robinson Crusoe Island. In event A during the cruise period, Chl-a subsurface maxima were associated with the arrival of a coastal meander originating on the continental shelf off Chile (remote process); the zooplankton was dominated by copepods and salps, with an evident coastal–oceanic gradient. In event B, Chl-a maxima were linked to a local upwelling forced by the intensification of a localized SSW wind. No influence of remote eddies or local Von Kármán vortices on Chl-a distribution was observed.
5. These findings highlight the influence of remote and local physical processes on the structure of planktonic communities around Robinson Crusoe Island. Understanding the variability of these mechanisms and their effects at the base of the pelagic food web is critical in adopting an ecosystem-level approach.