The role of ear environment in postharvest susceptibility of maize to toxigenic Aspergillus flavus

A kernel screening assay (KSA) was used to assess the genetic and environmental effects on the vulnerability of maize to aflatoxin accumulation. Kernels of 26 inbred lines that had been grown in seven environments, and 190 lines of the Intermated B73xMo17 (IBM) population grown in one location in the United States, were inoculated with a toxigenic strain of A. flavus and incubated in the dark at 30°C for 6 days. Percent kernel colonization (PKC), sporulation and aflatoxin were influenced by the maize genotypes (G), the location (“ear environment” or E) and the GxE interactions. Overall, low broad‐sense heritabilities were observed for PKC, sporulation and aflatoxin. PKC was significantly correlated with sporulation in all environments. Aflatoxin was positively correlated with colonization for two and with sporulation for all ear environments. Higher grain sulphur or magnesium in IBM was associated with less colonization or aflatoxin. Postharvest susceptibility of maize to aflatoxin is thus influenced by factors that are modulated by the ear environment. In a KSA, sporulation could be a proxy test for aflatoxin accumulation.     

Cylindrospermopsin effects on cell viability and redox milieu of Neotropical fish <Emphasis Type="Italic">Hoplias malabaricus</Emphasis> hepatocytes

Cylindrospermopsin (CYN) is a cyanotoxin that is cytotoxic to a wide variety of cells, particularly to the hepatocytes. In this study, the toxic effects of purified CYN were investigated in primary cultured hepatocytes of Neotropical fish Hoplias malabaricus. After isolation, attachment, and recovery for 72 h, the cells were exposed for 72 h to 0, 0.1, 1.0, 10, and 100 μg l^?1 of CYN. Then, cell viability and a set of oxidative stress biomarker responses were determined. Catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione S-transferase activities were not affected by exposure to CYN. Concentration-dependent decrease of glutathione reductase activity occurred for most CYN-exposed groups, whereas non-protein thiol content increased only for the highest CYN concentration. Lipid peroxidation, protein carbonylation, and DNA damage levels were not altered, but reactive oxygen species levels increased in the cells exposed to the highest concentration of CYN. Cell viability decreased in all the groups exposed to CYN. Thus, CYN may cause a slight change in redox balance, but it is not the main cause of cell death in H. malabaricus hepatocytes.     

Immunostimulatory effects of dietary poly‐β‐hydroxybutyrate in European sea bass postlarvae

The stable production of high‐quality fry in marine aquaculture is still hampered by unpredictable mortality caused by infectious diseases during larval rearing. Consequently, the development of new biocontrol agents is crucial for a viable aquaculture industry. The bacterial energy storage compound poly‐β‐hydroxybutyrate (PHB) has been shown to exhibit beneficial properties on aquatic organisms such as enhanced survival, growth, disease resistance and a controlling effect on the gastrointestinal microbiota. However, the effect of PHB on the developing immune system of fish larvae has so far not been investigated. In this study, the effect of feeding PHB‐enriched Artemia nauplii on survival, growth and immune response in European sea bass (Dicentrarchus labrax) postlarvae was examined. Amorphous PHB was administered to 28‐day‐old sea bass postlarvae over a period of 10 days. The survival and growth performance were monitored, and the expression of 29 genes involved in immunity, growth, metabolism and stress‐response was measured. While the expression of the insulin‐like growth factor 1 (igf1), an indicator of relative growth, was upregulated in response to feeding PHB, the larval survival and growth performance remained unaffected. After 10 days of PHB treatment, the expression of the antimicrobial peptides dicentracin (dic) and hepcidin (hep) as well as mhc class IIa and mhc class IIb was elevated in the PHB fed postlarvae. This indicates that PHB is capable of stimulating the immune system of fish early life stages, which may be the cause of the increased resistance to diseases and robustness observed in previous studies.     

A sensory and nutritional validation of open ocean mussels (Mytilus galloprovincialis Lmk.) cultured in SE Bay of Biscay (Basque Country) compared to their commercial counterparts from Galician Rías (Spain)

Mussel shell biometry, nutritional quality as well as consumer sensory evaluation of experimental open ocean cultured mussel Mytilus galloprovincialis (Lamarck 1819) were analyzed and compared to that of commercial mussels from Galician Rías available in the local market. Both mussel products were of the same commercial size. In this study, open ocean mussels were significantly higher and wider than those of Galician Rías. In addition, with the exception of ash content, both mussel products showed similar biochemical composition. Regarding fatty acid profiles, however, statistical differences were detected. These differences were not fully reflected in the sensory assessment. In terms of consumer acceptability, both mussel products were considered equally satisfactory.

     

Secondary Stress Responses in Juvenile Brazilian Flounder,Paralichthys orbignyanus,throughout and after Exposure to Sublethal Levels of Ammonia and Nitrite

This study investigated the secondary stress responses of Paralichthys orbignyanus exposed to ammonia and nitrite and after recovery. Fish were exposed to 0.12, 0.28, and 0.57 mg NH₃‐N/L, or 5.72, 10.43, and 15.27 mg NO₂‐N/L for 10 d followed by the same time length for recovery. Ammonia‐ and nitrite‐free water was used as a control treatment. Blood samples were collected after 1, 5, and 10 d of exposure and after recovery. Fish exposed to ammonia presented lower and higher glucose levels after 10 d of exposure and recovery, respectively. Ammonia induced initial and transient ionic disturbances and metabolic alkalosis. Nitrite exposure caused hyperglycemia, increased plasma K⁺ levels, and respiratory alkalosis, whereas metabolic acidosis was observed after recovery. Increased proportion of monocytes and/or granulocytes and reduced number of lymphocytes were demonstrated in fish exposed to 0.28 mg NH₃‐N/L (Day 1) and 10.43 mg NO₂‐N/L (Day 5) and after recovery in the 0.28 and 0.57 mg NH₃‐N/L treatments. Exposure to ammonia decreased the proportion of granulocytes on Day 5. In conclusion, exposure to concentrations at 0.12 mg NH₃‐N/L and 5.72 mg NO₂‐N/L provoked physiological disorders in Brazilian flounder. Nonetheless, fish exposed to 5.72 mg NO₂‐N/L following a 10‐d recovery period showed complete resumption of homeostasis.     

Vaccination of pigs with the S48 strain of Toxoplasma gondii – safer meat for human consumption

As clinical toxoplasmosis is not considered a problem in pigs, the main reason to implement a control strategy against Toxoplasma gondii (T. gondii) in this species is to reduce the establishment of T. gondii tissue cysts in pork, consequently reducing the risk of the parasite entering the human food chain. Consumption of T. gondii tissue cysts from raw or undercooked meat is one of the main sources of human infection, with infected pork being considered a high risk. This study incorporates a mouse bioassay with molecular detection of T. gondii DNA to study the effectiveness of vaccination (incomplete S48 strain) in its ability to reduce tissue cyst burden in pigs, following oocyst (M4 strain) challenge. Results from the mouse bioassay show that 100% of mice which had received porcine tissues from vaccinated and challenged pigs survived compared with 51.1% of mice which received tissues from non-vaccinated and challenged pigs. The presence (or absence) of T. gondii DNA from individual mouse brains also confirmed these results. This indicates a reduction in viable T. gondii tissue cysts within tissues from pigs which have been previously vaccinated with the S48 strain. In addition, the study demonstrated that the main predilection sites for the parasite were found to be brain and highly vascular muscles (such as tongue, diaphragm, heart and masseter) of pigs, while meat cuts used as human food such as chop, loin, left tricep and left semitendinosus, had a lower burden of T. gondii tissue cysts. These promising results highlight the potential of S48 strain tachyzoites for reducing the number of T. gondii tissues cysts in pork and thus improving food safety.     

Computed tomographic myelography of a foal with discospondylitis and extradural spinal cord compression due to a vertebral abscess

A one‐month‐old Quarter Horse colt presented with progressive gait abnormalities and weakness. The foal was ataxic at presentation. Radiography identified focal endplate irregularities and lysis at C6–7. Radiographic diagnosis was discospondylitis. Computed tomographic myelography was performed immediately following euthanasia and identified an extradural compressive spinal cord lesion corresponding to the site of discospondylitis. Post mortem examination findings included abscess formation at the C6–7 intervertebral space with osteomyelitis extending into the adjacent physes and subchondral bone of caudal C6 and cranial C7. The vertebral abscess extended into the ventral spinal canal at C6–7 and was identified as the cause of extradural spinal cord compression. Salmonella sp. was cultured and isolated from purulent exudate at the intervertebral space. Computed tomographic myelography has not been previously reported for assessment of discospondylitis in horses and was successful at accurately characterising spinal cord compression in addition to osteolytic changes associated with discospondylitis.     

Bursaphelenchus fungivorus (Nematoda: Aphelenchida) associated with Orthotomicus erosus (Coleoptera: Scolitydae) in Spain

A survey of the xylophagous insects in the conifer forests, mainly Pinus pinaster woodlands, in Spain was carried out in order to study the phoretic vectors of nematodes of the genus Bursaphelenchus. Fifteen environmental sites were characterized on the bases of altitude, rainfall, temperature and conifer species. Specimens of Orthotomicus erosus (n = 3476) were captured of which 59% carried nematodes under their elytrous, most of them were aphelenchid fungal‐feeding nematodes, but B. fungivorus was found on the beetles from Las Cumbres, Villa Blanca, (Huelva), southern Spain, which represent the first record of O. erosus as vector of a Bursaphelenchus sp. The nematode is characterized by morphometric and biomolecular techniques and distribution and ecology of the insect is discussed.