Effect of sublethal detergent concentration upon gill permeability of Ctenopharyngodon idella (pisces; cyprinidae)

Carp were exposed to different sublethal concentrations of sodium alkil-aril suphonate at 30 °C. The effect on the permeability of the fish gill membrane produced by detergent was measured as an increase in Na⁺ loss brought out by deionized water. Sodium loss was greater in control fish than in experimental ones. Sodium ion loss was inversely correlated with detergent concentrations, which reflects the occurrence of demineralization. This was proved by measuring plasmatic Na⁺ concentration in experimental and control fish. Sodium loss hyperbolic patterns may be indicative of carp hormonal control. Loss was probably influenced by the animals corporal weight.     

Survival and symbiotic properties of Bradyrhizobium japonicum in the presence of thiram: isolation of fungicide resistant strains

The fungicide thiram, widely used as a chemical seed protectant, induces a strong inhibition of primary nodulation in the crown zone of soybean roots. The present work reports on the isolation of Bradyrhizobium japonicum strains resistant to thiram, some of which (T3B, A86 and A2) maintained their capacity for nodulation and were still efficient symbionts, but some (A1, C1 and C6) lost the ability to stimulate nodulation. Characterization tests such as growth at different pH, denitrifying ability, salt tolerance, production of siderophores and phosphate solubilization were performed on the resistant strains. Inoculants produced from these strains could be appropriate for use with thiram-treated seeds, without causing a loss of bacteria viability. Received: 16 September 1996     

Manganese Supply and pH Influence Growth,Carboxylate Exudation and Peroxidase Activity of Ryegrass and White Clover

ABSTRACT

The effects of differential manganese (Mn) supply (0 to 355 μ M) and pH (4.8 and 6.0) on dry weight (DW), tissue concentrations of Mn, exudation of carboxylates, and the peroxidase activity were studied in ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) grown in nutrient solution. In both plant species, the increase in Mn supply caused a significant reduction in DW due to severe Mn toxicity, especially at pH 4.8. The critical toxicity concentration of Mn in shoots was 421 mg kg^{? 1} for ryegrass and 283 mg kg^{? 1} for white clover. For both plant species, an increase in Mn supply levels stimulated the exudation of carboxylates and the activity of peroxidase, which was related to stress conditions. The highest amount of carboxylates was exuded at pH 4.8. There was no clear effect of carboxylates on the complexation of Mn^{2 +}.     

Partial characterization of the digestive enzymes of Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> under culture conditions

The digestive enzyme activities of Pacific bluefin tuna Thunnus orientalis were evaluated for specific activity and characterized for pH and temperature optima in crude extracts of stomach, caecal mass, and proximal, middle and distal intestine. A higher level of alkaline proteolytic activity was detected in the caecal mass than in the proximal intestine. Total alkaline proteases, trypsin, chymotrypsin and leucine aminopeptidase (LAP) were tested. The temperature and pH analyses showed that proteolytic activity as well as lipase were maximal in the alkaline range, with a maximum at pH 9.0 and at temperatures between 35 and 60°C, except for the pepsin, which showed maximum activity at the same temperatures but in the acid range (pH 3.0). The α-amylase activity showed a broader range in activity, both for pH and temperature, with higher activity over the alkaline pH values and higher temperature. The lipase activity seems to be nondependent on bile salts under our assay conditions, resulting in a significant activity reduction in the presence of bile salts. This knowledge will allow the development of a gastrointestinal model (everted intestine) where food or feed will be hydrolysed with the fish’s own enzymes, a project that is being undertaken in our laboratory as a contribution to the development of novel diets for tuna fish.     

Coffee ripeness monitoring using a UAV-mounted low-cost multispectral camera

Coffee beverage quality is highly correlated with the degree of fruit ripeness. In this sense, monitoring fruit ripeness is of utmost importance for harvest planning and, especially for obtaining high-quality beverages. Currently, this process is carried out through manual counts of unripe fruits, which is laborious and limited to a few plants within the field. This study aimed at evaluating the potential of a low-cost multispectral camera for coffee ripeness monitoring in the Zona da Mata region of Minas Gerais State, Brazil. For that, five fields of Arabica coffee with distinct characteristics were evaluated. During the coffee ripeness period, four flights were carried using a Phantom 4 Pro quadcopter equipped with a Mapir Survey 3W camera for imagery acquisition. After that, nine vegetation indices (VIs) were obtained. For the same dates, the percentage of unripe fruits was obtained using an irregular grid in all fields. The data was split into two ripeness classes: suitable for harvest (R) with?<?30% of unripe fruits; and not suitable for harvest (U), with?>?30% of unripe fruits. Then, a principal component analysis was used to infer the importance of the VIs to discriminate plants with unripe fruits from those with ripe fruits. The first two principal components explained?>?75% of the variance in the datasets from all coffee fields. The VIs were able to discriminate the ripeness classes (U and R) in most fields; however, their performance was directly influenced by the crop yield and canopy volume.

     

Marine gammarids (Crustacea: Amphipoda): a new live prey to culture Octopus maya hatchlings

The effects of feeding two alternative live prey Hyalella azteca (freshwater gammarids) and Hyale media (marine gammarids) to Octopus maya hatchlings were compared with feeding adult Artemia sp., traditionally used during the first weeks of the life cycle. Hatchlings were fed ad libitum these three live preys during the first 15 days, and a paste elaborated with fresh squid and shrimp during the next 15 days when hatchling can be fed prepared diets. Weight (g) and specific growth rates (% day^?1) were determined every 15 days. Octopus maya hatchlings fed with marine gammarids grew larger (6.9 ± 0.2% day^?1) compared with hatchlings fed Artemia sp. or freshwater gammarids (4.8 ± 0.2% and 5.0 ± 0.3% day^?1 respectively). Survival was also higher (92.2 ± 6.8%) for hatchlings fed marine gammarids, than for those fed Artemia sp. (74.5 ± 23.8%) or freshwater gammarids (41.2 ± 21.2%). The content of acylglycerides, cholesterol and proteins in O. maya fed marine gammarids suggested a better nutrient assimilation by the hatchlings. Also, polyunsaturated fatty acids levels (EPA and DHA) were more abundant in marine gammarids, possibly contributing to the higher growth rates observed. This is the first study revealing a successful use of marine gammarids as alternative prey for octopus hatchlings culture.     

Preliminary trials on the use of large outdoor tanks for the ongrowing of Octopus maya juveniles

Octopus maya has high growth rates, direct embryonic development and high hatchling survival, making it a good candidate for aquaculture diversification. The present study was designed to evaluate growth rate, survival and food conversion of O. maya juveniles cultured in outdoor tanks. Octopuses were captured from the wild during the fishing season, and fed discarded fish heads and whole crabs. Three trials were conducted between 23 and 32 days, in September (trial 1), October (trial 2) and November (trial 3) where a decrease in sea water temperature was registered (29–24 °C, from September to November respectively). Octopuses were held in three outdoor tanks of 5 m² of bottom area and 0.5 m deep, aerated sea water and water flow allowing 10% of water exchange per day. Initial density was between 2.9 and 3.8 kg m^?3 with different initial mean weight of 542.3 ± 18.8, 493 ± 11.9 and 321 ± 7.8 g, for trials 1, 2 and 3 respectively. Specific growth rate varied between 1.8 and 2.7% BW day^?1 with no apparent relation with the culture temperature. These results put in evidence that tanks used are adequate for the ongrowing of O. maya juveniles, with commercial size being attained in a few weeks.     

Occurrence of antibodies to Toxoplasma gondii and Lepstospira spp. in manatees (Trichechus inunguis) of the Brazilian Amazon

The presence of Toxoplasma gondii and Leptospira spp. antibodies was investigated in 74 manatees (Trichechus inunguis [Mammalia: Sirenia]) kept in captivity in two rescue units in the northern region of Brazil. Antibodies to T. gondii were detected in 29 (39.2%) of 74 animals by using the modified agglutination test (titer, 1:25). For antibodies against Leptospira spp., sera were diluted 1:50 and tested against 24 strains ofleptospires by microscopic agglutination microtechnique, and positive samples were end titrated. Twenty-three (31.1%) of 74 animals were reactive to four serovars (Patoc 21/23, Castellonis 2/23, Icterohaemorrhagiae 1/23, and Butembo 1/ 23), with titers ranging from 100 to 1,600. This is the first report of antibodies against T. gondii and Leptospira spp. in T. inunguis from the Brazilian Amazon.     

Th1 and Th2 indices of the immune response in pigs vaccinated against Taenia solium cysticercosis suggest various host immune strategies against the parasite

Kinetics of the production of serum antibody levels and Th1 (IL-2, IFN-gamma) and Th2 (IL-4, IL-10) cytokines was studied in five pigs vaccinated with a synthetic tri-peptide vaccine (S3Pvac) against Taenia solium, a vaccine that has been shown protects pigs against naturally acquired infection. Healthy pigs of mixed genetic background, similar to those bred in rural villages of Mexico, were vaccinated with S3Pvac or with adjuvant alone, kept in sanitary conditions and bled at different times after vaccination to study the development of their specific immune response. Peripheral blood mononuclear cells (PBMCs) of vaccinated pigs showed a significant increment in the production of Th1 cytokines (IL-2 and IFN-gamma) but not of Th2 cytokines (IL-4 and IL-10) after specific PBLs stimulation with all the individual peptides. A Th1-inclined cytokine profile leading to an exacerbated local inflammation at the early installation stage of the cysticercus may possibly interfere with their successful establishment in the serum antibodies against total cysticercus antigens and against each of the three different peptides comprising S3Pvac were detected 7-51 days after vaccination. Antibodies against GK-1 interfered with the cysticerci development into intestinal tapeworms in prednisolone-treated hamsters. The sub-lethal crippling effect of anti-GK-1 antibodies upon cysticerci indicates to a therapeutic application of S3Pvac in infected pigs having potential epidemiological consequences, as it could aid in decreasing the number of tapeworms expected to develop from the few cysticerci that survive in the vaccinated pigs.