Influence of hatchery diets on early grow-out of the Cortez oyster Crassostrea corteziensis in Sinaloa, Mexico

We measured the growth and physiological condition of juveniles of the Cortez oyster Crassostrea corteziensis during the early grow-out phase in Sinaloa (Mexico) after using three experimental diets during the hatchery period: (1) 1:1 blend of the microalgae Isochrysis galbana and Chaetoceros muelleri as the control group; (2) mix of the same microalgae replaced by 50% of its wet weight with cornstarch; and (3) mix of the two microalgae replaced by 50% its wet weight with wheat flour. Specimens were cultivated under suspension conditions for 60 days and monitored weekly for growth (shell height and wet and dry weight) and the first 15 days for physiological response (condition index, digestive gland index and muscle index). Juveniles fed exclusively on microalgae attained larger sizes and had higher digestive gland and muscle indices, while those fed microalgae with cornstarch gained more biomass (wet and dry weight) and reached a better condition. The lowest values of these indicators occurred in oysters fed microalgae with wheat flour. Statistical data revealed that differences in the growth and condition of specimens between treatments were slight, confirming that mixed diets (particularly microalgae/cornstarch) have potential application for reducing hatchery-operating costs without affecting the performance of planted juveniles in the field.     

Pigment Composition of Nine Brown Algae from the Iberian Northwestern Coastline: Influence of the Extraction Solvent

Brown algae are ubiquitously distributed in the NW coastline of the Iberian Peninsula, where they stand as an underexploited resource. In this study, five solvents were applied to the extraction of pigments from nine brown algae, followed by their determination and quantification by HPLC-DAD. A total of 13 compounds were detected: Six were identified as chlorophylls, six were classified as xanthophylls, and one compound was reported as a carotene. Fucoxanthin was reported in all extracts, which is the most prominent pigment of these algae. Among them, L. saccharina and U. pinnatifida present the highest concentration of fucoxanthin (4.5–4.7 mg∙g⁻¹ dry weight). Ethanol and acetone were revealed as the most efficient solvents for the extraction of pigments, showing a maximal value of 11.9 mg of total pigments per gram of dry alga obtained from the ethanolic extracts of H. elongata, followed by the acetonic extracts of L. ochroleuca. Indeed, ethanol was also revealed as the most efficient solvent according to its high extraction yield along all species evaluated. Our results supply insights into the pigment composition of brown algae, opening new perspectives on their commercial exploitation by food, pharmaceutical, and cosmeceutical industries.     

Biochemical and molecular differences in diploid and triploid ocean-type chinook salmon (<Emphasis Type="Italic">Oncorhynchus tshawytscha</Emphasis>) smolts

There is increasing evidence for complex dosage effects on gene expression, enzyme activity and phenotype resulting from induced ploidy change. In this study, ocean-type chinook salmon were bred using a 2 × 2 factorial mating design to create four families and test whether triploidization resulted in changes in growth performance and smolting. Eggs were pressure shocked after fertilization to create triploid fish from a subset of each family. In June, fish were sampled for size, plasma insulin-like growth factor 1 (IGF-1), gill Na⁺–K⁺-ATPase activity, and expression of two Na⁺–K⁺-ATPase α subunits in the gill. Diploids were significantly heavier than triploids, and there were significant differences due to family. Despite a significant positive correlation between plasma IGF-1 and fish size, plasma IGF-1 did not differ between diploid and triploid smolts. Diploids also had significantly greater gill Na⁺–K⁺-ATPase enzyme activities than triploids and there was a strong family effect. Gill Na⁺–K⁺-ATPase α1b isoform expression differed significantly by family, but not ploidy, and generally families with lower Na⁺–K⁺-ATPase enzyme activity had higher α1b isoform gene expression. Na⁺–K⁺-ATPase α1a isoform expression did not differ among any of the groups. Although diploids were larger and had higher specific activities of Na⁺–K⁺-ATPase in the gills, there was no difference in gene expression or circulating hormone levels. The strong family effect, however, suggests that strain selection may be useful in improving performance of triploids for aquaculture.     

Induction of cachexia in mice by systemically administered myostatin

Mice and cattle with genetic deficiencies in myostatin exhibit dramatic increases in skeletal muscle mass, suggesting that myostatin normally suppresses muscle growth. Whether this increased muscling results from prenatal or postnatal lack of myostatin activity is unknown. Here we show that myostatin circulates in the blood of adult mice in a latent form that can be activated by acid treatment. Systemic overexpression of myostatin in adult mice was found to induce profound muscle and fat loss analogous to that seen in human cachexia syndromes. These data indicate that myostatin acts systemically in adult animals and may be a useful pharmacologic target in clinical settings such as cachexia, where muscle growth is desired.     

Baryons at the edge of the X-ray-brightest galaxy cluster

Studies of the diffuse x-ray-emitting gas in galaxy clusters have provided powerful constraints on cosmological parameters and insights into plasma astrophysics. However, measurements of the faint cluster outskirts have become possible only recently. Using data from the Suzaku x-ray telescope, we determined an accurate, spatially resolved census of the gas, metals, and dark matter out to the edge of the Perseus Cluster. Contrary to previous results, our measurements of the cluster baryon fraction are consistent with the expected universal value at half of the virial radius. The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web.     

Cells infected with Jaagsiekte sheep retrovirus are detected in the bone marrow of asymptomatic sheep

Ovine pulmonary adenocarcinoma (OPA) is a transmissible lung cancer caused by Jaggsiekte sheep retrovirus (JSRV). It is difficult to identify animals infected with JSRV but are clinically healthy. The virus does not induce a specific antibody response and, although proviral DNA sequences of JSRV can be found in mononuclear blood cells, the detection is inconsistent. The aim of this study was to investigate the presence of JSRV in the bone marrow of infected sheep and develop a more consistent screening method. Immunohistochemical examination of bone marrow samples from 8 asymptomatic JSRV-infected sheep revealed the presence of positively labelled cells. However, JSRV could not be detected by a highly sensitive polymerase chain reaction (PCR) in bone marrow aspirates periodically collected from these animals. Results suggest that JSRV-infected cells may be present in the bone marrow of symptomless animals, but the number is below the detectable level for PCR. Therefore, this technique does not seem to be helpful for preclinical diagnosis of OPA.     

Performance of outdoor seawater treatment systems for recirculation in an intensive turbot (Scophthalmus maximus) farm

Water treatment systems are mandatory in recirculating aquaculture facilities facing existing regulations, but data on system efficiency, especially for marine species, are scarce. The present work aimed at contributing to the evaluation of the effluent characteristics and the performance of a combined outdoor biological and non-biological treatment system in an intensive turbot (Scophthalmus maximus) farm, operating under different hydraulic regimes. A preliminary study on the biofilter bacterial populations was also undertaken. Changes in effluent characteristics with pumping, season of the year and fish biomass were observed. The treatment system showed performance instability under the conditions assayed (outdoors, changeable recycle rates). Maximum removal of solids was observed in winter, with microscreen or biological filtration (up to 60%) and nitrite removal (40–98%) was achieved with ozonation. Reduction in ammonium levels was higher in summer, either mechanically (74%) or biologically (33%). Phosphate removal was higher in winter with both systems (37 and 60%, respectively). Compliance with Portuguese discharge standards was achieved. For improvements in the treatment loop, further studies on biofilter bacteria under outdoor conditions are needed, and biological denitrification is encouraged. This revised version was published online in August 2006 with corrections to the Cover Date.     

Patterns of effects of arbuscular mycorrhizal fungi on plants grown in contaminated soil

Arbuscular mycorrhizal fungi (AMF) are integral functioning parts of plant root systems and are widely recognized for enhancing plant growth on severely disturbed sites, including those contaminated with heavy metals. However, the generality of detailed patterns observed for their influence on various metals and oxidative‐stress parameters in multiple plant species is not clarified. The goal of this study was to investigate the patterns of metal‐stress alleviation by AMF in four plant species. For this purpose, clover, sunflower, mustard, and phacelia were inoculated with Glomus intraradices and compared to noninoculated plants grown under heavy metal–stressed conditions. The study focused on the effect of AMF inoculation on plant biomass, assimilating pigments, total protein, superoxide dismutase and peroxidase activity, lipid peroxidation and As, Cd, Co, Cu, Fe, Mn, P, Pb, U, and Zn contents. As a result of inoculation very different patterns of variation were obtained for concentrations of elements and for biochemical parameters in plants. The particular effect of AMF inoculation on plants was species‐ and metal‐specific, although there was a general enhancement of plant growth.     

Nanopore sequencing for the detection and identification of Xylella fastidiosa subspecies and sequence types from naturally infected plant material

Xylella fastidiosa (Xf) is a gram-negative bacterial plant pathogen that can infect over 500 plant species. While it is endemic in America, X. fastidiosa subsp. pauca was reported for the first time in Europe in 2013 on olive trees in southern Italy. The availability of fast, sensitive, and reliable diagnostic tools is indispensable for managing current and future outbreaks of Xf. In this paper, we use the OXford Nanopore Technologies (ONT) MinION platform for detecting and identifying Xf at species, subspecies, and sequence type (ST) level. Two workflows were developed: the first one provided a “shotgun” strategy, that is, exploring the possibility of detecting Xf within DNA extracted from plant samples. This allowed detection of Xf by direct DNA sequencing and identifying the subspecies only in samples with high bacterial levels. Nanopore amplicon sequencing was pursued as a second workflow. This consists of PCR amplification of a set of seven multilocus sequence typing (MLST) fragments, officially adopted for identifying Xf at type strain level, followed by Nanopore-sequencing of the amplicons and an ad hoc pipeline to generate MLST consensus calls. This combined approach, which takes only a few hours, allowed the detection and identification of Xf at ST level in plant material with low bacterial infection.