Agar‐based pellets as feed for sea urchins (Paracentrotus lividus): rheological behaviour,digestive enzymes and gonad growth

The algal polysaccharide agar has long been used as a food binder due to its structure, rheological behaviour, stability and interactions – properties that help to generate firm, round, disk‐shaped pellets that may be used in recirculating sea urchin‐rearing systems. Three algae‐based diets (Ulva lactuca, Gracilaria gracilis, Cystoseira sp.) containing 3% and 6% agar were tested on the sea urchin Paracentrotus lividus in order to examine the effect of varying percentages of agar on pellet stability in water and sea urchin gonad growth. The kinetics of water absorption and solute leaching of pellets were measured by immersing quadruplicate samples of the pellets in water for 1, 2, 3, 4, 5 and 6 days. Our results show that the pellets had good water stability, were readily consumed by sea urchins and the presence of agar did not hamper sea urchin gonad growth. Animals fed Ulva‐containing pellets reached a more advanced gametogenic stage with respect to animals fed Cystoseira‐ and Gracilaria‐containing pellets. Moreover, the presence of agarase activity in the digestive system indicated that agar may be an energy source. Pellets are relatively low cost and easy to prepare and store. They may represent a useful resource for rearing sea urchins under intensive conditions.     

Germ cell chimerism: absence in parabiotic frogs

Embryos of the leopard frog deprived of primordial germ cells by treatment with ultraviolet light were joined in parabiosis with normal, unirradiated embryos. The irradiated member of the pair was not colonized by germ cells from its normal partner. Unlike the primordial germ cells of birds and mammals, the germ cells of frog embryos are not carried by the circulating blood.     

Origin of the West Nile virus responsible for an outbreak of encephalitis in the northeastern United States

In late summer 1999, an outbreak of human encephalitis occurred in the northeastern United States that was concurrent with extensive mortality in crows (Corvus species) as well as the deaths of several exotic birds at a zoological park in the same area. Complete genome sequencing of a flavivirus isolated from the brain of a dead Chilean flamingo (Phoenicopterus chilensis), together with partial sequence analysis of envelope glycoprotein (E-glycoprotein) genes amplified from several other species including mosquitoes and two fatal human cases, revealed that West Nile (WN) virus circulated in natural transmission cycles and was responsible for the human disease. Antigenic mapping with E-glycoprotein-specific monoclonal antibodies and E-glycoprotein phylogenetic analysis confirmed these viruses as WN. This North American WN virus was most closely related to a WN virus isolated from a dead goose in Israel in 1998.     

Employment of Marine Polysaccharides to Manufacture Functional Biocomposites for Aquaculture Feeding Applications

In this study, polysaccharides of marine origin (agar, alginate and κ-carrageenan) were used to embed nutrients to fabricate biocomposites to be employed in animal feeding. The consistency of biocomposites in water has been evaluated up to 14 days, by several methods: swelling, nutrient release and granulometric analysis. Biocomposites were produced with varying percentages of nutrients (5%–25%) and polysaccharides (1%–2%–3%). All possible biopolymer combinations were tested in order to select those with the best network strength. The best performing biocomposites were those manufactured with agar 2% and nutrients 10%, showing the lowest percentage of water absorption and nutrient release. Biocomposites made of agar 2% and nutrients 10% were the most stable in water and were therefore used to analyze their behavior in water with respect to the release of quercetin, a phenolic compound with demonstrated high antibacterial and antioxidant activities. The leaching of such molecules in water was therefore employed as a further indicator of biocomposite water stability. Altogether, our results confirm the suitability of agar as a binder for biocomposites and provide a positive contribution to aquaculture.     

Development of a multiplex RT-PCR assay for simultaneous detection of the major viruses that affect rainbow trout (Oncorhynchus mykiss)

The major viral diseases that affect rainbow trout (Oncorhynchus mykiss) are viral haemorrhagic septicaemia, infectious haematopoietic necrosis, infectious pancreatic necrosis and sleeping disease. In the presented study, we developed a multiplex RT-PCR (mRT-PCR) assay for the simultaneous detection of these four rainbow trout viruses in a single assay. The choice of primers was carried out based on the expected size of the fragments, the temperature and time required for the amplification, and the specificity for the target sequence. Firstly, the method was optimised using reference strains of viral haemorrhagic septicaemia virus (VHSV), infectious haematopoietic necrosis virus (IHNV), infectious pancreatic necrosis virus (IPNV) and sleeping disease virus (SDV) cultivated with permissive cell culture lines; subsequently, the method was used for the identification of these viral infections in rainbow trout samples. Twenty-two samples of rainbow trout, clinically suspected of having viruses, were analysed by the developed method to detect the presence of the four viruses, by directly analysing the animal tissues. The mRT-PCR method was able to efficiently detect the viral RNA in infected cell culture supernatants and in tissue samples, highlighting the presence of single infections as well as co-infections in rainbow trout samples. VHSV/SDV and IHNV/SDV co-infections were demonstrated for the first time in rainbow trout. The mRT-PCR method was revealed to be an accurate and fast method to support traditional diagnostic techniques in the diagnosis of major viral diseases of rainbow trout.     

Effectiveness of shore‐based remote camera monitoring for quantifying recreational fisher compliance in marine conservation areas

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Endocrine and ultrasonographic aspects of the oestrous cycle of the mule

The blood serum concentrations of progesterone and estradiol-17beta were measured at various stages of the oestrous cycle of seven female mules, and their reproductive tracts were examined ultrasonographically at the same stages.     

Diagnosis of cystic echinococcosis on sheep farms in the south of Argentina: areas with a control program

In 2000 Guarnera et al. proposed using ELISA in canine faeces collected from the ground to detect dogs infected with Echinococcus granulosus, thus determining sheep farms with active transmission. The objective was to evaluate the prevalence of E. granulosus infection in sheep farms of the Patagonia. Sheep farms were randomly selected in the Provinces of Río Negro, Chubut, Neuquén, Santa Cruz and Tierra del Fuego (areas with control programs) and La Pampa (comparison area). From one to three samples of fecal matter were obtained for each sheep farm, which were processed by means of copro-ELISA test with confirmation of positive samples by copro-Western blot. A total of 1042 samples were obtained from 352 sheep farms, 26 (7.3%) proving positive. Of these 5 (6.3%) were from La Pampa, 9 (13.8%) from Neuquén, 4 (4.7%) from Río Negro, 2 (2.9%) from Chubut, 1 (5.9%) from Santa Cruz and 5 (13.9%) from Tierra del Fuego. The identification of parasitized dogs is an essential activity upon which rests the strategy of control and surveillance. Arecoline tests or coproantigen test with fecal matter obtained directly from the dog contribute information on individual prevalence, while the use of coproantigens detected in ground-collected samples transfers the dog unit of observation to units of greater epidemiological value. In the present experience, the technique employed seems promising for its application in systems of epidemiological surveillance of cystic echinococcosis and in drawing a baseline on which to measure the progress of control programs in the Argentine Patagonia in subsequent years.     

Cognitive interaction after staged callosal section: evidence for transfer of semantic activation

Sensory and cognitive functions were assessed in a right-handed male before and after partial and complete callosal commissurotomy. After the initial posterior section was made, there was no evidence of interhemispheric sensory transfer, although the left hemisphere did have access to stimulus-related semantic and episodic information from the right hemisphere. After the callosum was completely sectioned, this exchange was no longer observed.