Karyotype stasis in four Atlantic Scombridae fishes: mapping of classic and dual-color FISH markers on chromosomes

Fish from the family Scombridae exhibit a biogeographical pattern that includes pelagic habits, high swimming ability, and migratory behavior of its species. Although genetic studies aimed at the management and conservation of some of its more intensely exploited species are available, cytogenetic analyses of Scombridae are scarce. In the present study, individuals of four species of this family were obtained in the vicinity of the St. Peter and St. Paul Archipelago in the Mid-Atlantic region. The chromosomes of these four species were analyzed using conventional staining, Ag-NORs, C-banding, CMA₃/DAPI fluorochrome staining, and dual-color FISH with 18S and 5S rDNA probes. Acanthocybium solandri and Scomberomorus brasiliensis showed 2n = 48 chromosomes (2st + 46a; FN = 50), while Thunnus albacares and T. obesus, which also had 2n = 48 chromosomes, share another karyotype structure (2m + 2st + 44a; FN = 52). Discrete heterochromatic blocks are present in the centromeric regions of the chromosomes. 18S rDNA/Ag-NORs/CMA₃ ⁺/DAPI^?sites are located on the short arms of a subtelocentric pair that is apparently homeologous among the four species. The 5S rDNA genes on pair 24 are conserved in all of the species. Cytogenetic patterns showed a high degree of chromosomal conservation between the species. However, Thunnus species displayed greater karyotypic differentiation than A. solandri and S. brasiliensis. Pericentric inversions seem to be the primary mechanism involved in karyotype differentiation in this important fish group.     

Compatibility of traditional and novel acaricides with bumblebees (Bombus terrestris): a first laboratory assessment of toxicity and sublethal effects

BACKGROUND: This project assessed the potential hazards of different classical and novel acaricides against an important non‐target and beneficial insect for the pollination of wild flowers and cultivated crops, the bumblebee Bombus terrestris (L). Twenty‐three acaricides used commercially in the control of phytophagous mites (Acari) were tested in greenhouses and/or the open field. Side effects included acute mortality and also sublethal effects on nest reproduction. The different compounds were administered in the laboratory via three different worst‐case field scenario routes of exposure: dermal contact and orally via the drinking of treated sugar water and via treated pollen. The compounds were tested at their respective maximum field recommended concentration (MFRC), and, when strong lethal effects were observed, a dose–response assay with a dilution series of the MFRC was undertaken to calculate LC₅₀ values. RESULTS: From the different acaricide classes, several chemistries caused high levels of acute toxicity in bumblebee workers, especially bifenthrin and abamectin which resulted in 100% mortality by contact. In addition, several acaricides tested were found to have a detrimental effect on drone production. For oral exposures via treated sugar water, the dose–response assay showed the LC₅₀ values for abamectin, bifenazate, bifenthrin and etoxazole to be 1/15 MFRC (1.17 mg AI L^?1), 1/10 MFRC (9.6 mg AI L^?1), 1/83 MFRC (0.36 mg AI L^?1) and 1/13 MFRC (4.4 mg AI L^?1) respectively, indicating that their use should be carefully evaluated. CONCLUSION: Overall, the results suggest that most of the acaricides tested are compatible with bumblebees, with the exceptions of abamectin, bifenazate, bifenthrin and etoxazole. However, the risks also depended on the type of treatment. As a result, the sugar water treatment seems to present the worst‐case situation of exposure, indicating that this approach is suitable for determining the hazards of pesticides against bumblebees. Finally, it is suggested that future tier testing under more field‐related conditions is required for a final decision of their risks. Copyright © 2010 Society of Chemical Industry     

Apparent digestibility of soybean coproducts in extruded diets for Nile Tilapia,Oreochromis niloticus

Soybean coproducts are important protein sources in aquaculture because of their amino acid profile. Tilapia can be reared on soybean coproducts as the only source of dietary protein without compromising growth. This study estimated apparent digestibility coefficients for five soybean coproducts for juvenile Nile tilapia, Oreochromis niloticus, fed with extruded diets. A reference diet and test diets consisting of 70% reference diet and 30% coproduct ingredient were formulated, along with 5.0 g kg^?1 chromic oxide (Cr₂O₃) as a marker. Apparent digestibility coefficients (ADC) for dry matter (ADCDM), gross energy (ADCGE) and crude protein (ADCCP) for soybean coproducts were estimated as 84.2–88.4%, 86.9–91.1% and 96.8–97.9%, respectively. ADCDM and ADCCP values did not vary among the ingredients, but low‐protein soybean meal exhibited lower ADCGE values than did soybean protein concentrate. ADCs of all amino acids were >95%, and mean ADCs for amino acids were similar to the values observed for ADCCP. Soybean coproducts had good nutritional value in extruded diets fed to tilapia. Methionine, histidine and valine were the limiting amino acids in all evaluated ingredients.     

Conditioning,maturation and year‐round natural spawning of orange‐spotted grouper,Epinephelus coioides (Hamilton, 1822), in recirculating aquaculture system

The present experiment was aimed at studying the conditioning, maturation and natural spawning of orange‐spotted grouper, Epinephelus coioides, in a recirculatory aquaculture system (RAS). Thirty fish (n = 30; 3.35 ± 0.05 kg) were stocked in a circular tank of 125 m³ capacity fitted with an RAS for conditioning and broodstock development. After 15 days, 15 fish were implanted with 17 α methyl testosterone and letrozole at the rate of 5 mg and 0.2 mg/kg body weight, respectively, for conversion from female to male. The gonadal development started after 1 month, and by 90th day, 63.53 ± 3.78% and 2.07 ± 0.84% of the oocytes attained a size of 400–500 μm and 500–600 μm respectively. Natural spawning commenced in the RAS from 4th month onward after stocking and spawning continued round the year. The spawning pair showed courtship behaviour with a typical vertical burst of swimming just before release of gametes. The total number of eggs spawned during 1 year was 47.23 million with spawning frequency varying form 5 to 13 times per month. The association of spawning events with new moon day (lunar cycle) weakened as time progressed. The mean monthly fertilization and hatching rates varied from 77.80 ± 3.34% to 83.70 ± 1.76% and 82.80 ± 4.21% to 88.33 ± 1.39% respectively. The study proved that RAS is an efficient system that provides a stable, controllable and conducive environment for year‐round natural breeding of orange‐spotted grouper.     

The oscillatory bioelectrical signal from plants explained by a simulated electrical model and tested using Lempel-Ziv complexity

This paper demonstrates the oscillatory characteristics of electrical signals acquired from two ornamental plant types (Epipremnum pinnatum and Philodendron scandens - Family Araceae), using a noninvasive acquisition system. The electrical signal was recorded using Ag/AgCl superficial electrodes inside a Faraday cage. The presence of the oscillatory electric generator was shown using a classical power spectral density. The Lempel and Ziv complexity measurement showed that the plant signal was not noise despite its nonlinear behavior. The oscillatory characteristics of the signal were explained using a simulated electrical model that establishes that for a frequency range from 5 to 15 Hz, the oscillatory characteristic is higher than for other frequency ranges. All results show that non-invasive electrical plant signals can be acquired with improvement of signal-to-noise ratio using a Faraday cage, and a simple electrical model is able to explain the electrical signal being generated.     

Constraints for future cocoa production in Ghana

To address the growing global demand for cocoa, sustainable intensification of its production in West Africa is considered crucial. This paper analyzes the determinants of cocoa productivity and profitability by smallholder farmers in Ghana to provide insights into challenges for future cocoa farming, which will guide the formulation and prioritization of tailored policies to address them. A four-stage sampling technique was used to select a total of 731 cocoa farmers from various districts in all six cocoa growing regions in Ghana. Selected farmers were interviewed using a semi-structured questionnaire. The results show that cocoa productivity and profitability was very low with an average of 234 kg ha^?1 and Gh¢ 568 (ca. US$ 150) per ha, respectively. Farm management practices, namely control of capsid and black pod disease, fertilizer application and pruning, significantly (p < 0.05) influenced cocoa productivity. Capsid control and fertilizer application showed the highest impact on productivity. Farm size, however, had a negative impact, which implies that increase in farm size results in decreased smallholder cocoa productivity. Farmers should be encouraged to sustainably intensify farm management through controlling black pod disease and capsids, regular pruning and efficient application of fertilizer rather than focusing on excessive land expansion, which eventually hampers productivity and biodiversity.     

Number of flocks on the same litter and carcase condemnations due to cellulitis, arthritis and contact foot-pad dermatitis in broilers

1. This study was conducted to verify the impact of different kinds of material and the number of times of litter reuse on the incidence of chicken pathologies. Approximately 4·5 million broilers from conventional Brazilian farms were evaluated in the abattoir for cellulitis, arthritis and contact foot-pad dermatitis. 2. Four different kinds of litter material, Brachiaria grass, corncob, sawdust and rice shell, were used. Brachiaria grass litter showed the highest incidence of contact foot-pad dermatitis. Corncob litter also showed some negative effects on foot quality. Broilers raised on rice shell litter showed good results in terms of the incidence of contact foot-pad dermatitis. The best results were obtained with sawdust litter, because the incidence of cellulitis and arthritis were the lowest and the incidence of contact foot-pad dermatitis was also very low.     

Genetic variability among sugarcane genotypes based on polymorphisms in sucrose metabolism and drought tolerance genes

Target region amplification polymorphism (TRAP) markers were used to estimate the genetic similarity (GS) among 53 sugarcane varieties and five species of the Saccharum complex. Seven fixed primers designed from candidate genes involved in sucrose metabolism and three from those involved in drought response metabolism were used in combination with three arbitrary primers. The clustering of the genotypes for sucrose metabolism and drought response were similar, but the GS based on Jaccard’s coefficient changed. The GS based on polymorphism in sucrose genes estimated in a set of 46 Brazilian varieties, all of which belong to the three Brazilian breeding programs, ranged from 0.52 to 0.9, and that based on drought data ranged from 0.44 to 0.95. The results suggest that genetic variability in the evaluated genes was lower in the sucrose metabolism genes than in the drought response metabolism ones.