Dietary organic acids blend alone or in combination with an essential oil on the survival,growth, gut/liver structure and de hemato‐immunological in Nile tilapia Oreochromis niloticus

This study evaluated the effects of dietary supplementation of organic acids blend (OAB) alone or in combination with essential oil, Lippia origanoides (OAE) for Nile tilapia fed supplemented diets for 30 days. Fish (1.1 ± 0.04 g) were fed control (Control), or OAB 0.5% or OAB 0.5% + essential oil 0.125% (OAE) respectively. At the end of the experiment, samples were collected for de hemato‐immunological, histological analysis of the intestine and liver, as well as microbiology of the intestine. The pH of the diets supplemented with OAB and OAE reduced 0.92 and 0.19 respectively. The growth and FCR were unaffected by the treatments, but survival was significantly higher in the OAB treatment. Fish fed the OAB diet showed reduced concentration of total heterotrophic bacteria and Pseudomonas sp. in the intestine. Increased glucose in fish fed OAB and high number of circulating monocytes in fish fed OAE diet were observed. The anterior intestine of fish fed OAE diet showed larger number of goblet cells and increased villi height. The diet supplemented with OAB, mainly, improved the intestinal health and survival of tilapia juveniles and can be used in juvenile production.     

Microbial biomass as an antioxidant for tilapia feed

Microbial biomass (MB) produced by different industries is thought to be a beneficial supplement in fish feed due to high contents of antioxidants and pigments. However, little is known about their impact on fish health. In this experiment, 960 tilapia (26.84 ± 1.03 g) were fed one of eight experimental diets—a control diet with no MB (C), a control diet with vitamin E (VE) and six diets with three types of MB at two concentrations (0.25% and 0.5%): Rubrivivax gelatinosus (RG25 and RG50), Spirulina platensis (SP25 and SP50) and Saccharomyces cerevisiae (SC25 and SC50). Adding MB to diets decreased plasma total oxidant status, malonaldehyde and leucocyte respiratory burst; increased the total antioxidant status; and did not affect the blood biochemical parameters. In flesh, the use of the MB lowered the thiobarbituric acid‐reactive substances and increased redness (except for SC) and carotenoid deposition (except SC25). So, it was concluded that the use of the MB provided an antioxidant effect in tilapia blood plasma, decreased lipid oxidation and increased pigmentation and carotenoid deposition in the fish flesh, without imparting a negative impact on the animals’ health.     

Evaluation of genetic diversity and plant growth promoting activities of nitrogen-fixing bacilli isolated from rice fields in South Brazil

Several strains of bacilli, mainly species of the genera Bacillus and Paenibacillus, displaying important plant growth promoting (PGP) characteristics were isolated from seven distinct rice production zones of the Rio Grande do Sul State, Brazil. Of 296 isolates, 155 were from rhizospheric soil and 141 from bulk soil. In order to evaluate the diversity among the isolates of each bacterial population the Shannon index was used on a 70% similarity basis. Diversity indices varying from 2.27 to 5.51 were obtained. Using principal coordinate analysis (PCA) to correlate bacterial diversity with soil parameters, it was found that soil pH was the characteristic most closely related to bacilli diversity. The bacilli isolated were also analyzed for some PGP activities. Of those 296 isolates, 94 and 148 produced between 0.1 and 30 μg of indole-3-acetic acid (IAA) ml⁻¹ in vitro after 72 and 144 h of incubation, respectively. Twenty-two isolates were able to solubilize phosphate and 32 isolates produced siderophores. Paenibacillus and Bacillus genera were the most prominent groups in the rhizosphere and soil populations analyzed. Paenibacillus borealis was the most frequent species in both locations. The isolate SVPR30, identified by 16S rRNA gene sequence analysis as a strain of Bacillus sp., was chosen for in vivo greenhouse experiments and proved to be very efficient in promoting a significant increase in the roots and shoot parts of rice plants. The identification and isolation of PGP bacilli from temperate and subtropical soils, which combine the ability to fix nitrogen with the production of substances capable to promote the plant growth, could significantly increase productivity of grain crops in Brazil.     

Use of trichostatin A alters the expression of HDAC3 and KAT2 and improves in vitro development of bovine embryos cloned using less methylated mesenchymal stem cells

The aim of this work was to investigate the methylation and hydroxymethylation status of mesenchymal stem cells (MSC) from amniotic fluid (MSC‐AF), adipose tissue (MSC‐AT) and fibroblasts (FIB‐control) and to verify the effect of trichostatin A (TSA) on gene expression and development of cloned bovine embryos produced using these cells. Characterization of MSC from two animals (BOV1 and BOV2) was performed by flow cytometry, immunophenotyping and analysis of cellular differentiation genes expression. The cells were used in the nuclear transfer in the absence or presence of 50 nM TSA for 20 hr in embryo culture. Expression of HDAC1, HDAC3 and KAT2A genes was measured in embryos by qRT‐PCR. Methylation results showed difference between animals, with MSC from BOV2 demonstrating lower methylation rate than BOV1. Meanwhile, MSC‐AF were less hydroxymethylated for both animals. MSC‐AF from BOV2 produced 44.92 ± 8.88% of blastocysts when embryos were exposed to TSA and similar to embryo rate of MSC‐AT also treated with TSA (37.96 ± 15.80%). However, when methylation was lower in FIB compared to MSC, as found in BOV1, the use of TSA was not sufficient to increase embryo production. MSC‐AF embryos expressed less HDAC3 when treated with TSA, and expression of KAT2A was higher in embryos produced with all MSC and treated with TSA than embryos produced with FIB. The use of MSC less methylated and more hydroxymethylated in combination with embryo incubation with TSA can induce lower expression of HDAC3 and higher expression of KAT2A in the embryos and consequently improve bovine embryo production.     

Environmental Quality and Cytogenotoxic Impact of the Waters of a Stream Receiving Effluents from Tannery Industry

Water, Air, & Soil Pollution - Cu-based copper nanoclusters have generated a great deal of interest based on for their fluorescent and catalytic properties. However, as heterogeneous catalysts,...     

Speciation driven by recombination in the evolution of tomato curly stunt virus in Mozambique

Begomoviruses constitute a group of viruses of great economic importance in agriculture, mainly in tropical and subtropical regions, including southern Africa. Tomato curly stunt virus (ToCSV) is an important begomovirus described in South Africa and later reported in Mozambique impacting tomato cultivation. In Mozambique, the severe disease caused by ToCSV limits tomato cultivation and compromises the income of small and medium farms. Due to the scarcity of information about this pathogen, in this study we explored its genetic variability to elucidate the mechanisms that drive its evolution. In 2019, 27 ToCSV full-length sequences were obtained from tomato foliar samples with virus-like symptoms collected in the district of Chokue in Gaza province, Mozambique. Sequence analysis showed that isolates from Mozambique have a nucleotide identity of 90.9%–96.9% with the isolate from South Africa (AF261885) and are grouped into two distinct strains that we named ToCSV-Chok I and ToCSV-Chok II. The ToCSV-Chok II strain has a higher nucleotide diversity than ToCSV-Chok I in the Rep gene. Recombination is involved in the evolutionary history of ToCSV, with both intraspecific and interspecific recombination events detected in the Rep gene. Our results indicate a prevalence of ToCSV in tomato crops in the Chokue district of Mozambique (the major tomato-producing region of the country) and suggest that ToCSV is undergoing speciation due to the effect of recombination.     

Does Rhipicephalus microplus tick infestation increase the risk for myiasis caused by Cochliomyia hominivorax in cattle?

The larval phase of Cochliomyia hominivorax (screwworm) is an obligate parasite of vertebrate animals, particularly mammals, and widespread in South America, where it remains one of the most important parasitic diseases of domestic animals. The skin of cattle highly infested by ticks, with cutaneous lesions, exudation of tissue fluid and blood scent seems to produce the ideal environment for fly attraction. However, an association between these parasites was never investigated. The aim of this work was to verify if there is an association between Rhipicephalus microplus tick load and the occurrence of C. hominivorax myiasis in cattle, and to quantify the risk. Sixty bovine (Bos taurus taurus, Angus breed) under field conditions were observed for 24 weeks, during which weekly tick counts and examination for the presence of myiasis were performed. There was a significant association between a high tick burden (24-week mean above 50 ticks per animal) and myiasis occurrence (P = 0.0102). The calculated relative risk (RR) for C. hominivorax myiasis occurrence in cattle with high tick burden was 3.85 (CI95% = 1.23–12.13); indicating that cattle highly parasitized by R. microplus have about four times more risk of myiasis than those with a low parasite load. As far as we aware, this is the first statistically based evidence of the relationship between R. microplus parasitic load and occurrence of myiasis by C. hominivorax. This result could be useful for the design of integrated control strategies for these parasites and to provide more information for the understanding of cattle tick parasitism in cattle production.     

Autochthonous probiotic bacteria modulate intestinal microbiota of Pirarucu,Arapaima gigas

This study aimed to investigate the ability of two probiotic strains (Lactococcus lactis subsp. lactis and Enterococcus faecium) to colonize Arapaima gigas intestines and their competence in modulating gut microbiota, morphology, and immunological status. A total of 135 A. gigas (58.86 ± 10.25 g) were divided into three treatments: (a) fish fed a diet containing L. lactis subsp. lactis at 1 × 10⁸ CFU^?1, (b) fish fed a diet containing E. faecium at 1 × 10⁸ CFU^?1, and (c) fish fed a diet nonsupplemented with probiotic. After 21 days, 12 fish per treatment were sampled. Blood and posterior intestine were sampled for further analysis. High‐throughput sequencing results demonstrated that the relative abundance of Cetobacterium genus was high in all treatments. The number of thrombocytes increased in both groups fed the probiotic, and eosinophils were higher in fish fed E. faecium. Serum antimicrobial activity of fish fed L. lactis subsp. lactis was higher when compared with the other two treatments. In conclusion, both strains could populate the intestinal mucosa of A. gigas and could be used as probiotics in pirarucu production as they can influence hematoimmunological parameters and decrease the abundance of pathogenic bacteria in the gut of pirarucu within 21 days of feeding.