Multilocus sequence typing (MLST) analysis of California Flavobacterium psychrophilum reveals novel genotypes and predominance of CC‐ST10 in California salmonid hatcheries

The Gram‐negative bacterium, Flavobacterium psychrophilum, is endemic to California, USA, where it is an important pathogen in salmonid aquaculture, especially in rainbow trout (Oncorhynchus mykiss). Disease outbreaks caused by F. psychrophilum in rainbow trout fingerlings can approach 90% mortality, resulting in millions of dollars of economic losses annually. The focus of this study was to investigate the genetic diversity of 49 F. psychrophilum isolates collected from disease outbreaks in 17 salmonid hatcheries in California, USA, from 2015 to 2018 using multilocus sequence typing. Results suggest California F. psychrophilum isolates are diverse, representing 11 distinct sequence types (STs), three of which were previously undescribed. Still, the majority of genotyped isolates (n = 41) belonged to a single clonal complex (CC), CC‐ST10, which is the largest CC worldwide and has been linked to disease outbreaks on several continents. Results of this study provide evidence of marked intraspecific genetic diversity of F. psychrophilum from California. The biological significance of this genetic variability is unclear but could have implications for future vaccine development and treatments. Further studies investigating the virulence, antigenic, and antimicrobial susceptibility profiles of F. psychrophilum are warranted to better understand the epizootiology of this pathogen in the Western United States.     

Determination of relationships among autochthonous grapevine varieties (Vitis vinifera L.) in the Northwest of the Iberian Peninsula by using microsatellite markers

Fifty six grapevine varieties traditionally grown in the Northwest region of the Iberian Peninsula were analysed for six microsatellite loci, in order to determine the relationships among them as well as the plant material that should be collected and preserved in germplasm banks. Previous morphological and molecular results were taken into account for assessment of the existing synonymies among accessions from different European countries. Percent distribution of the main alleles was calculated. Multivariate analysis was carried out and similarities among the studied material were described and commented.     

Combination of pelleting and monensin does not affect antioxidant properties and fatty acids in milk of grazing dairy cows supplemented with a concentrate containing soybean seeds

This study was performed with the main objective of evaluating the effect of the combination of pelleting and monensin on fatty acids (FA) composition, the concentration of total polyphenols and flavonoids, and the oxidative stability of milk in cows fed a concentrate containing soybean seeds. Eight Holstein multiparous cows were distributed in a replicated Latin square design. The four supplement treatments consisted of the combination of two factors (pelleting and monensin) and one concentrate as follows: (1) unpelleted concentrate with no monensin (CO); (2) pelleted concentrate with no monensin (PE); (3) unpelleted concentrate with 96 mg of monensin/kg of dry matter, DM (MO); and (4) pelleted concentrate with 96 mg of monensin/kg of DM (PM). There was no interaction between pelleting and monensin for milk production and concentration of milk protein, lactose, total polyphenols, flavonoids, conjugated dienes (CD), and reducing power. Fat and total solids concentration in milk were decreased when cows were fed pelleted (PE and PM) concentrates. Feeding cows with PE and PM concentrates increased the CD concentration in milk. Regarding milk FA concentration, there was no difference among treatments for total saturated, monounsaturated, and polyunsaturated FA. The most prominent result was that pelleting increased the milk concentration of omega-3 FA. Altogether, the present study suggests that the pelleting process can improve the milk fat quality by increasing the omega-3 FA, while the combination of pelleting and monensin in the diet of grazing dairy cows fed soybean-based concentrate adds no further improvements to FA profiles and oxidative stability of milk.

     

New protocol to separate llama sperm without enzymatic treatment using Androcoll-E™

The objective of this study was to design a protocol to separate spermatozoa from seminal plasma of raw llama semen without prior enzymatic treatment using a single-layer centrifugation with Androcoll-E^™ (AE). Two experiments were performed: (a) samples were divided into three aliquots (1 ml) that were deposited on the top of 4, 5 or 6 ml of AE and were centrifuged at 800g for 20 min and (b) samples were divided into two aliquots (1 ml) that were deposited on the top of 4 ml of AE and were centrifuged at 600g or 1,000g for 20 min. Columns of 5 and 6 ml of AE showed a total sperm motility (TM) significantly lower, while in the 4 ml column, this parameter was not different from the TM of samples before the AE treatment. The percentage of spermatozoa with intact and functional membranes, normal morphology and intact acrosomes, as well as the percentages of sperm with highly condensed chromatin, was conserved (p ˃ .05) in the three column heights and in the two centrifugation speeds evaluated. In conclusion, the different column heights of AE (4, 5 and 6 ml) and the different centrifugation speeds used (600, 800 and 1,000g) allow separating spermatozoa of raw llama semen without enzymatic treatment, preserving the evaluated sperm characteristics. However, of all the studied treatments, centrifugation in the 4 ml column of AE at 800g would be the method of choice to process raw llama semen samples destined for reproductive biotechnologies.     

Pseudocercospora griseola,the causal agent of common bean angular leaf spot: Strain characterization and sensitivity to fungicides

Angular leaf spot (ALS), an important disease of common bean (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola. This pathogen has a wide genetic variability and, therefore, poses a challenge to integrated disease management. The use of resistant cultivars is difficult; hence, the application of fungicides has been a common practice in common bean cultivation. P. griseola strains were morphophysiologically characterized and their sensitivity to common fungicides used to control ALS was studied. The strains were evaluated for sporulation capacity and a representative sample of 34 strains was bioassayed to determine their sensitivity to commercial concentrations of five fungicides, namely pyraclostrobin, mancozeb, pyraclostrobin + metconazole, chlorothalonil and tebuconazole. Another sample of 29 strains was studied for conidial germination and dimensions. Sporulation capacity ranged from 0.88 to 27.67 × 10⁴ conidia/ml and germination percentage ranged from 39% to 72%. The large differences among strains suggest a wide genetic variability among the strains. A wide variability in aggressiveness of P. griseola was observed, which has consequences for breeding programmes aimed at resistance. The behaviour of pathogen strains differed in every fungicide evaluated, even in a population that has not been under selection pressure in the field. These results confirm the need for further studies and may guide future research with this pathogen.     

Visceral leishmaniasis in a captive crab-eating fox Cerdocyon thous

Visceral leishmaniasis (VL) is a zoonotic disease with worldwide distribution. The crab-eating fox (Cerdocyon thous) is considered a wild reservoir of many zoonotical diseases, particularly VL. This study reported the presence of Leishmania infantum amastigotes in different organs of one captive C. thous found dead in a zoo. This animal was positive by the indirect fluorescence antibody test and had many clinical signs of VL. Intracellular amastigote forms of L. infantum were seen in neutrophils and macrophages in sample tissues from skin, lymph nodes (popliteal, submandibular, prescapular, and mesenteric), spleen, and liver. The numbers of positive cells and intracellular parasites were higher in macrophages than in neutrophils. In addition, polymerase chain reaction demonstrated extensive distribution of Leishmania DNA in C. thous tissues from multiple organs. The presence of intracellular amastigotes in neutrophils and macrophages as well as DNA of the parasite in tissues, specifically skin demonstrate that this crab-eating fox is an adequate host for L. infantum and reinforce the importance of VL for symptomatic wild canids kept in captivity in endemic areas.     

Effect of zeolites on cultures of the marine micro-algae Emiliania huxleyi

The yield of cultures of Emiliania huxleyi, a coccolithophore marine micro-alga species, in natural seawater and in seawater previously exposed to elutriates of ZEBEN-06 and ZESTEC-56, two zeolitic-nature products (ZNPs) (supernatant of 2.0 g l⁻¹ of ZNP in natural seawater, stirred for 30 min) was evaluated. Total concentrations of dissolved trace metals and organic ligands (and respective conditional stability constants) in the initial media and at 7th day cultures were determined, by anodic and cathodic striping voltammetry. The changes introduced by the ZNPs in the media significantly enhanced E. huxleyi growth yield, the effect being more extent in the ZESTEC-56 elutriate. It was observed that both the ZNPs enriched the seawater with trace and not toxic quantities of Mn. In addiction, ZEBEN-06 removed small fractions of Cu and Zn from the media. The ZEBEN-06 elutriate stimulated the cell exudation but that of ZESTEC-56 inhibited exudation. Algae were also incubated in a culture medium with 0.05 g l⁻¹ ZESTEC-56 in situ, and the growth yield was similar to that of the control culture. ZEBEN-06 was not studied in situ because it was hard to distinguish its particles from the cells, during cells counting. The ZESTEC-56 in situ enriched the medium in Mn, Cu, Pb and Cd, but impoverished it in Zn. The cell exudation was about four times higher in the presence of the ZNP in situ. Liberation/adsorption of micro-nutrients at the surface of the zeolites seems to be the cause of the observed changes in the biological response of the algae. The yield of the algal growth has economic relevance in aquaculture. On the other hand, ZNP are cheap, only small amounts (few mg l⁻¹) are required and the addition of some nicro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may be economically advantageous. However, it is recommendable an previous investigation, in order to select the zeolitic characteristics and concentration that will maximise the algal yield in each particular case (alga nature and seawater trace metal contents).