Differentially expressed genes identified through RNA‐seq with extreme values of principal components for beef fatty acid in Nelore cattle

The aim of this study was to identify differentially expressed genes (DEG) in the Longissimus thoracis muscle of Nelore cattle related to fatty acid (FA) profile through RNA sequencing and principal component analysis (PCA). Two groups of 10 animals each were selected containing PC1 and PC2 extreme DEG values (HIGH × LOW) for each FA group. The intramuscular fat (IMF) was compared between cluster groups by ANOVA, and only the sum of monounsaturated FA (MUFA) and ω3 showed significant differences (p < .05). Interestingly, the highest percentage (95%) of phenotypic variation explained by the sum of the first two PC was observed for ω3, which also displayed the lowest number of DEG (n = 1). The lowest percentage (59%) was observed for MUFA, which also revealed the largest number of DEG (n = 66). Since only MUFA and ω3 exhibited significant differences between cluster groups, we can conclude that the differences observed for the remaining groups are not due to the percentage of IMF. Several genes that have been previously associated with meat quality and FA traits were identified as DEG in this study. The functional analysis revealed one KEGG pathway and eight GO terms as significant (p < .05), in which we highlighted the purine metabolism, glycolytic process, adenosine triphosphate binding and bone development. These results strongly contribute to the knowledge of the biological mechanisms involved in meat FA profile of Nelore cattle.     

Genomic prediction for meat and carcass traits in Nellore cattle using a Markov blanket algorithm

This study was carried out to evaluate the advantage of preselecting SNP markers using Markov blanket algorithm regarding the accuracy of genomic prediction for carcass and meat quality traits in Nellore cattle. This study considered 3675, 3680, 3660 and 524 records of rib eye area (REA), back fat thickness (BF), rump fat (RF), and Warner–Bratzler shear force (WBSF), respectively, from the Nellore Brazil Breeding Program. The animals have been genotyped using low-density SNP panel (30 k), and subsequently imputed for arrays with 777 k SNPs. Four Bayesian specifications of genomic regression models, namely Bayes A, Bayes B, Bayes Cπ and Bayesian Ridge Regression methods were compared in terms of prediction accuracy using a five folds cross-validation. Prediction accuracy for REA, BF and RF was all similar using the Bayesian Alphabet models, ranging from 0.75 to 0.95. For WBSF, the predictive ability was higher using Bayes B (0.47) than other methods (0.39 to 0.42). Although the prediction accuracies using Markov blanket of SNP markers were lower than those using all SNPs, for WBSF the relative gain was lower than 13%. With a subset of informative SNPs markers, identified using Markov blanket, probably, is possible to capture a large proportion of the genetic variance for WBSF. The development of low-density and customized arrays using Markov blanket might be cost-effective to perform a genomic selection for this trait, increasing the number of evaluated animals, improving the management decisions based on genomic information and applying genomic selection on a large scale.     

Effects of beneficial bacteria on biomass,photosynthetic parameters and cell composition of the microalga Muriellopsis sp. adapted to grow in seawater

The present study evaluated the effects of five bacterial isolates from the microalga Muriellopsis sp. on the microalgal biomass concentration (g/L), specific growth rate (K), photosynthetic quantum yield (QY), non‐photochemical quenching (NPQ), maximum relative electron transport rates (rETR max) and levels of nutritional components such as carbohydrates, lipids, proteins and carotenoids in Muriellopsis sp. cultivated in seawater under indoor and outdoor conditions. The bacterial strains were Microbacterium sp. Dom 1; Pseudomonas sp. Dom2; Microbacterium sp. Dom 3; Rhizobium sp. Dom 4; and Dietzia sp. Dom 5, as well as the Pseudoalteromonas sp. (SLP1), a bacterium known to promote the growth of microalgae. At the laboratory level, inoculation of the strains SLP1, Dom 1, Dom 3 and Dom 5 resulted in higher specific growth rates and biomass of the microalga. Subsequently, the best results were obtained with a combination of the selected bacterial strains (Dom1, Dom 3, Dom5 and SLP1) under outdoor culture conditions improved the biomass, proteins, carbohydrates and total carotenoids in 22.12%, 48.28%, 19,25% and 48.27%, respectively, compared to cultures without the incorporation of the selected bacteria (control), while no effects were observed on the photosynthetic parameters. Thus, it was demonstrated that positive associations of the selected bacterial strains played an important role in the production of Muriellopsis sp. acclimatized to grow in seawater. This is of crucial importance, especially in desert areas, where solar radiation is high and freshwater is a limited resource.     

Analysis of bacterial community and bacterial nutritional enzyme activity associated with the digestive tract of wild Chilean octopus (Octopus mimus Gould, 1852)

Information on the bacterial community associated with octopus is very scarce, unlike fish and other molluscs. This study revealed the bacterial community associated with digestive tract of wild Chilean octopus Octopus mimus using a culture‐dependent method and 16S rDNA clone library. Moreover, we analysed the bacterial nutritional enzyme activity of culturable bacteria. A culture‐dependent method showed that the composition of the culturable bacterial community was substantially different between female and male octopus. The predominant species in female octopus were Vibrionaceae and Streptococcaceae, whereas only Vibrionaceae was dominated in male octopus. Bacterial nutritional enzyme activities of culturable bacteria from male octopus were much higher than female octopus. The 16S rDNA clone library analysis showed that the bacterial community of male octopus exhibited a higher diversity than that of female octopus. The genus Mycoplasma was the predominant bacteria in the digestive tract of all octopus samples. The results obtained in this study raise the possibility that each octopus has different food consumption due to different bacterial community and nutritional enzyme activity, although Mycoplasma sp. is one of the predominant bacteria in the digestive tract. Moreover, our results are useful for the future of microbiological investigation associated with the octopus and for probiotics in the octopus aquaculture.     

Thermal preference and tolerance of green abalone Haliotis fulgens (Philippi, 1845) and pink abalone Haliotis corrugata (Gray, 1828)

The thermoregulatory behaviour of green abalone Haliotis fulgens and pink abalone H. corrugata was investigated. Haliotis fulgens juveniles ranging in wet weight from 3.0 to 3.3 g and from 28.7 to 30.5 mm shell length and of H. corrugata 2.0 g and 25.7 mm in shell length were exposed to 19°C for 30 days in a flow‐through water system. Temperature preference was determined in a horizontal thermal gradient and was found to be 25.4°C for green abalone and 25.0°C for pink abalone. Displacement velocity was 4.3 cm h⁻¹ for H. fulgens and 12.8 cm h⁻¹ for H. corrugata. The optimum temperature for growth calculated for both abalone species was 24.6 and 24.5°C respectively. The critical thermal maxima (CTMax) of H. fulgens and H. corrugata were determined as a measure of thermal tolerance. Abalones were subjected to increasing water temperatures at a rate of 1°C on 30 min until they detached from the substrate. The CTMax at 50% were 33.6 and 32.0°C for green and pink abalone respectively. The results are discussed in relation to site selection and commercial rearing.     

Effects of rhodium heterogeneous catalyst and isomerization conditions on linoleic acid conjugation of soybean oil

Rhodium heterogeneous catalyst was used to catalyze isomerization of linoleic acid in soybean oil to conjugated linoleic acid (CLA). A central composite rotatable design with five levels of three variables, namely, reaction temperature, stirring speed, and reaction time, was used to determine the maximum CLA yield. The formation of CLA during isomerization was greatly dependent on the reaction temperature and time. The CLA content of soybean oil increased from 0.63 to 202.42 mg/g oil when isomerization was done at 200 degrees C, with a stirring speed of 200 rpm for 49 min. Analysis of triacylglycerol positions showed that linoleic acid at any position in a triacylglyceride could possibly be isomerized to CLA.     

Antifungal activity of strawberry fruit volatile compounds against Colletotrichum acutatum

Eight volatile products characterizing strawberry aroma, which is generated from the oxidative degradation of linoleic and linolenic acids by a lipoxygenase (LOX) pathway, were examined because of their antifungal activity against Colletotrichum acutatum, one of the causal agents of strawberry anthracnose. In this study, the effects of aldehydes, alcohols, and esters on mycelial growth and conidia development were evaluated. (E)-Hex-2-enal was found to be the best inhibitor of mycelial growth [MID (minimum inhibitory doses)=33.65 microL L(-1)] and of spore germination (MID=6.76 microL L(-1)), while hexyl acetate was the least effective of all volatile compounds tested (MID=6441.89 microL L(-1) for mycelial growth and MID=1351.35 microL L(-1) for spore germination). Furthermore, the antifungal activity of (E)-hex-2-enal on susceptibility of strawberry fruits to C. acutatum was also confirmed. The presence of these molecules in jars containing strawberry fruits inoculated with a suspension of spores inhibited the fungus growth and prevented the appearance of symptoms. Moreover, a study of the effects of (E)-hex-2-enal on conidial cells of C. acutatum was evaluated by transmission electron microscopy. This volatile compound altered the structures of the cell wall and plasma membrane, causing disorganization and lysis of organelles and, eventually, cell death.