Comprehensive diversity assessment of walnut-associated xanthomonads reveal the occurrence of distinct Xanthomonas arboricola lineages and of a new species (Xanthomonas euroxanthea) within the same tree

Xanthomonas arboricola pv. juglandis (Xaj) is the aetiological agent of walnut diseases causing economic losses on walnut production worldwide. This phytopathogen is spread around the world where walnuts are produced and has a considerable genetic diversity. Using a comprehensive sampling methodology, focusing on factors that could influence the diversity of walnut-colonizing Xaj in Portugal, this work provides new insights on xanthomonad populations on walnut. Genetic diversity was assessed by multilocus sequence analysis (MLSA) and dot blot hybridization patterns on 131 Xanthomonas isolates obtained from 64 walnut trees considering epidemiological metadata such as year of isolation, distinct bioclimatic regions, production regimes, and host-related features. The results showed that the majority of isolates were split into 17 lineages of Xaj, while the other isolates clustered in four MLSA groups that did not include Xaj strains. These four groups were represented by three lineages of X. arboricola, and 11 lineages of Xanthomonas spp., including strains assigned to the recently proposed new species Xanthomonas euroxanthea. Furthermore, distinct Xaj, X. arboricola, and Xanthomonas spp. were isolated from the same walnut tree, suggesting possible genetic admixture within the same host. Phylogenetic analysis through geoBurst revealed the high diversity of these Xanthomonas spp. populations. Assessment of type III effector genes gave the indication that some Xanthomonas spp. strains were nonpathogenic on walnut, with the exception for X. euroxanthea CPBF 424. Altogether, these findings add to the thorough characterization of walnut-associated xanthomonads in Portugal, providing a comprehensive snapshot of the current diversity that could contribute to risk assessment analysis and improve phytosanitary control.     

Protection from challenge following administration of a canarypox virus-vectored recombinant feline leukemia virus vaccine in cats previously vaccinated with a killed virus vaccine

OBJECTIVE: To compare protection against FeLV challenge obtained following administration of 2 doses of an adjuvanted, chemically inactivated, whole FeLV (FeLV-k) vaccine with protection obtained following administration of 1 dose of an FeLV-k vaccine followed by 1 dose of a canarypox virus-vectored recombinant FeLV (rCP-FeLV) vaccine. DESIGN: Prospective study. ANIMALS: Thirty-two 9-week-old domestic shorthair cats. PROCEDURE: Cats received 2 doses of the FeLV-k vaccine SC, 21 days apart (n = 11); 1 dose of the FeLV-k vaccine SC and, 21 days later, 1 dose of the rCP-FeLV vaccine transdermally (11); or 2 doses of physiologic saline (0.9% NaCl) solution (control; 10). Four weeks after the second vaccine dose, all cats were challenged with FeLV by means of oronasal administration. Blood samples were collected at weekly intervals beginning 21 days after challenge, and serum was tested for FeLV antigen. RESULTS: All 10 control cats became persistently infected (ie, FeLV antigen detected in > or = 3 consecutive serum samples) following FeLV challenge, whereas only 1 of 11 cats that received 2 doses of the FeLV-k vaccine and none of the 11 cats that received 1 dose of the FeLV-k vaccine and 1 dose of the rCP-FeLV vaccine did. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that protection against FeLV challenge obtained following SC administration of a single dose of an FeLV-k vaccine followed, 21 days later, by transdermal administration of a single dose of an rCP-FeLV vaccine was similar to that obtained following SC administration of 2 doses of the FeLV-k vaccine 21 days apart.     

Potassium Fertilization in Sugarcane Ratoon Yield Grown in a Tropical Region

ABSTRACT

Potassium (K) is closely associated to the improvement of sugarcane quality, acting in the conversion of reducing sugar (RS) to recoverable sugars (TRS). The present study aimed to evaluate the effect of different levels of K-fertilization on the yield and technological quality of sugarcane ratoons grown under edaphoclimatic conditions in the Brazilian central region. The experiment was carried out using the sugarcane variety CTC-4, in a Distrofic Latosols, medium texture (270 g clay kg^?1). The study was arranged in a randomized complete block design, with five treatments (0; 50; 100; 150 and 200 kg K₂O ha^?1), and five replicates. Potassium content in soil and plant, biometric variables, stalk yield and the technological quality at harvest were evaluated. The 200 kg ha^?1 dose increased the K content in 160, 156, 56 and 3% in 0–0.20 and 0.20–0.40 m layers at 180 and 360 days after budding (DAB), respectively, promoting greater absorption of the nutrient by plants (X ? = 15.22 g kg^?1). The higher potassium absorption reflected in yield gains, with an increasing of 7.9%, compared to the control treatment, yielding 100.37 t ha^?1. However, soil K fertilization did not affect the technological quality of the sugarcane ratoon.

Abbreviations: K: potassium; RS: reducing sugars; TRS: recoverable sugars; DAB: days after budding; SB: Sum of Bases; CEC: Cation Exchange Capacity; V: Saturation Base; Kcl: potassium chloride; AWC: Available water capacity; PC: Pol percent in sugarcane; Brix: total soluble solids; dRYL: Dystrophic Red Yellow Latosol; eRYA: Eutrophic Red Yellow Argisol.     

Evaluation of the Antioxidant and Antimicrobial Activity of Protein Hydrolysates and Peptide Fractions Derived from Colossoma macropomum and Their Effect on Ground Beef Lipid Oxidation

The objective of this study was to obtain protein hydrolysate from the mechanically separated meat of blackfin pacu to evaluate the influence by ultrafiltration in the antioxidant and antimicrobial activities of the peptide fractions obtained and to apply in ground beef to evaluate the lipid stability. The enzymatic hydrolysis was performed using the enzyme Protamex (pH 7.0, 60°C) for 240 min. The protein hydrolysate was fractionated by ultrafiltration. Then, the antioxidant capacity of the protein hydrolysate and the peptide fractions were evaluated in vitro by the methods of 2,2’-azinobis (3-ethylbenzothiazoline sulfonic acid) radical capture, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay, reducing power, and hydroxyl radical scavenging activity. The antimicrobial activity of the samples was evaluated by disc-diffusion against Staphylococcus aureus and Escherichia coli. After evaluation, the peptide fractions did not present higher bioactivities than that shown for the hydrolysate. The protein hydrolysate was applied to ground beef, where the substances reactive to thiobarbituric acid and color were evaluated during 7 days of storage at 4°C. Lipid oxidation was reduced up to 60.9% and there was no modification of the natural coloration. Thus, the protein hydrolysate can be used as an alternative source of antioxidant for the preservation of refrigerated meats.     

Evaluation of Macroalgae Sulfated Polysaccharides on the Leishmania (L.) amazonensis Promastigote

The sulfated polysaccharides from Solieria filiformis (Sf), Botryocladia occidentalis (Bo), Caulerpa racemosa (Cr) and Gracilaria caudata (Gc) were extracted and extensively purified. These compounds were then subjected to in vitro assays to evaluate the inhibition of these polysaccharides on the growth of Leishmania (L.) amazonensis promastigotes. Under the same assay conditions, only three of the four sulfated polysaccharides were active against L. amazonensis, and the polysaccharide purified from Cr was the most potent (EC₅₀ value: 34.5 μg/mL). The polysaccharides derived from Bo and Sf demonstrated moderate anti-leishmanial activity (EC₅₀ values of 63.7 μg/mL and 137.4 μg/mL). In addition, we also performed in vitro cytotoxic assays toward peritoneal macrophages and J774 macrophages. For the in vitro cytotoxicity assay employing J774 cells, all of the sulfated polysaccharides decreased cell survival, with CC₅₀ values of 27.3 μg/mL, 49.3 μg/mL, 73.2 μg/mL, and 99.8 μg/mL for Bo, Cr, Gc, and Sf, respectively. However, none of the sulfated polysaccharides reduced the cell growth rate of the peritoneal macrophages. These results suggest that macroalgae contain compounds with various chemical properties that can control specific pathogens. According to our results, the assayed sulfated polysaccharides were able to modulate the growth rate and cell survival of Leishmania (L.) amazonensis promastigotes in in vitro assays, and these effects involved the interaction of the sulfated polysaccharides on the cell membrane of the parasites.     

Morphological and physiological parameters influence the use efficiency of nitrogen and phosphorus by Eucalyptus seedlings

New Forests - Morpho-physiological characteristics in Eucalyptus species can determine N (NUE) and P (PUE) use efficiency and, consequently, the plant's responses to fertilization. The study...     

Plastic gear loss estimates from remote observation of industrial fishing activity

Derelict fishing gear is a highly visible source of marine plastic pollution, causing mortality and ecosystem degradation with uncertain long-term consequences. The quantity of derelict gear entering the oceans remains unknown because of heterogeneity in fishing gear and effort, as well as inadequate monitoring. Prior studies have been limited in scope to specific fisheries and regions, and large-scale estimates lack an empirical basis. It is critically important for decision makers to have credible information in order to design effective remediation efforts. We estimated the amount of industrial fishing effort and the associated plastic debris entering the ocean globally each year from lost fishing gear. Using remote observations of fishing vessel activity paired with technical fishing gear models, we generated a bounding estimate for gear operation and loss worldwide in 2018. We estimate that industrial trawl, purse-seine and pelagic longline fisheries operated 2.1 Mt of plastic gear over 2018 to obtain 49.7 Mt of retained and discarded catch, representing 74% of industrial marine capture globally. The median estimate for plastic gear lost during the use of these gear types was 48.4 kt (95% confidence interval: 28.4–99.5 kt). This estimate excludes abandoned and discarded gear. Improved observation, especially of small-scale fisheries, is needed to better understand the sources of derelict gear. These findings serve as a benchmark for future monitoring and management efforts to reduce derelict gear in the global ocean.     

Modulation of the innate immune response,antioxidant system and oxidative stress during acute and chronic stress in pacu (Piaractus mesopotamicus)

Fish Physiology and Biochemistry - Stress is an energy-demanding process, as well as the responses of the innate immune system, that impose a metabolic overload on cellular energy production, which...     

Vulnerability of the biota in riverine and seasonally flooded habitats to damming of Amazonian rivers

1. The extent and intensity of impacts of multiple new dams in the Amazon basin on specific biological groups are potentially large, but still uncertain and need to be better understood.
2. It is known that river disruption and regulation by dams may affect sediment supplies, river channel migration, floodplain dynamics, and, as a major adverse consequence, are likely to decrease or even suppress ecological connectivity among populations of aquatic organisms and organisms dependent upon seasonally flooded environments.
3. This article complements our previous results by assessing the relationships between dams, our Dam Environmental Vulnerability Index (DEVI), and the biotic environments threatened by the effects of dams. Because of the cartographic representation of DEVI, it is a useful tool to compare the potential hydrophysical impacts of proposed dams in the Amazon basin with the spatial distribution of biological diversity. As the impact of Amazonian dams on the biota of both rivers and periodically flooded riparian environments is severe, DEVIs from different Amazonian tributary basins are contrasted with patterns of diversity and distribution of fish, flooded forest trees and bird species.
4. There is a consistent relationship between higher DEVI values and the patterns of higher species richness and endemism in all three biological groups. An assessment of vulnerability at the scale of tributary basins, the assessment of biodiversity patterns related to DEVI, and the analysis of teleconnections at basin scale, demonstrate that recent construction of dams is affecting the biota of the Amazon basin.
5. The evidence presented here predicts that, if currently planned dams are built without considering the balance between energy production and environmental conservation, their cumulative effects will increase drastically and represent a major threat to Amazonian biodiversity.