Polyphasic characterization of Aeromonas salmonicida isolates recovered from salmonid and non‐salmonid fish

Michigan's fisheries rely primarily upon the hatchery propagation of salmonid fish for release in public waters. One limitation on the success of these efforts is the presence of bacterial pathogens, including Aeromonas salmonicida, the causative agent of furunculosis. This study was undertaken to determine the prevalence of A. salmonicida in Michigan fish, as well as to determine whether biochemical or gene sequence variability exists among Michigan isolates. A total of 2202 wild, feral and hatchery‐propagated fish from Michigan were examined for the presence of A. salmonicida. The examined fish included Chinook salmon, Oncorhynchus tshawytscha (Walbaum), coho salmon, O. kisutcha (Walbaum), steelhead trout, O. mykiss (Walbaum), Atlantic salmon, Salmo salar L., brook trout, Salvelinus fontinalis (Mitchill), and yellow perch, Perca flavescens (Mitchill). Among these, 234 fish yielded a brown pigment‐producing bacterium that was presumptively identified as A. salmonicida. Further phenotypic and phylogenetic analyses identified representative isolates as Aeromonas salmonicida subsp. salmonicida and revealed some genetic and biochemical variability. Logistic regression analyses showed that infection prevalence varied according to fish species/strain, year and gender, whereby Chinook salmon and females had the highest infection prevalence. Moreover, this pathogen was found in six fish species from eight sites, demonstrating its widespread nature within Michigan.     

Topographic laparoscopy for buffaloes in the quadruped position

This study aimed to describe the anatomical topography of the abdominal cavity of buffaloes in the quadruped position to establish the best endosurgical access and vantage points and identify possible limitations. Laparoscopies were performed on 10 healthy female buffaloes obtained from the Universidade Federal Rural da Amazônia to explore possible access points to the abdomen. Techniques for assessing and possibly observing certain organs and structures through the left and right flanks of 10 animals have been described. In five animals, access was created through the right side of the last intercostal space to allow more cranial access to the abdominal cavity. Despite the presence of the rumen, access through the left flank allowed the visualization of the structures of the gastrointestinal tract and the genitourinary system. With access through the right flank, however, imaging was hampered by the presence of the greater omentum and its deep and superficial walls, which prevented the progression of the endoscope. Access through the last right intercostal space allowed the visualization of the cranial structures of the abdominal cavity, such as the caudate process, right lobe of the liver, right kidney, and pancreas. Laparoscopic access through the left flank and the last intercostal space in healthy buffaloes in the quadruped position is feasible, and it is promising for the exploration, diagnosis, and treatment of various disorders in buffaloes.     

Using public databases for genomic prediction of tropical maize lines

In this paper, the aims were (a) to test the usefulness of using genomic and phenotypic information from public databases (open access) to predict genetic values for tropical maize inbred lines regarding plant and ear height; (b) to identify how the population structure, the use of optimized training sets (OTSs) and the amount of information originating from public databases affect the predictive ability. Thus, 29 training sets (TSs) were defined considering three diversity panels: the University of São Paulo (USP—validation set (VS)) and the ASSO and USDA North Central Regional Plant Introduction Station (NCRPIS) (external public panels—predictors), which were divided into four scenarios with different TS configurations. We showed that it is possible to use public datasets as a primary TS and that population structure can modify the predictive abilities of GS. In the four scenarios proposed, very large or very small sets did not provide predictive abilities over 0.53 for GS. However, OTSs composed of 250 individuals were sufficient to achieve predictive abilities over this limit.     

Meagre’s melatonin profiles under captivity: circadian rhythmicity and light sensitiveness

The present study reveals the first characterization of the plasma melatonin rhythms of the meagre (Argyrosomus regius) under aquaculture conditions. Melatonin levels were monitored during a 24 h cycle under a photoperiod of 16 L:8D and under constant darkness (DD), respectively to characterize the daily rhythm of this indoleamine and to test its endogenous origin. Besides, to identify which light intensities are perceived as night or day by this species, the degree of inhibition of nocturnal melatonin production caused by increasing intensities of light was tested (3.3, 5.3, 10.5, and 120 μW/cm²), applying 1 h light pulses at Mid-Dark. The result for melatonin daily rhythm in plasma showed a typical profile: concentration remained low during all daytime points, increasing greatly during dark points, with maximum values at 16:00 and 22:00 h, zeitgeber time. Under DD conditions, the plasma melatonin profile persisted, with a similar acrophase but with a lower amplitude between subjective day and night periods, indicating this rhythm as being endogenously driven. Moreover, meagre seemed to be very sensitive to dim levels of illumination during the night, since an intensity of just 3.3 μW/cm² inhibited melatonin production. However, only the pulse of 5.3 μW/cm² caused a melatonin drop till daytime concentrations. Thus, the threshold of light detection by the pineal organ was suggested as being located between 3.3 and 5.3 μW/cm². Such results are an added value for this species biology knowledge, and in consequence to its adaptation to aquaculture conditions, allowing the improvement of culture husbandry protocols.     

Freezing injury in primary and secondary needles of Mediterranean pine species of contrasting ecological niches

? Pine seedlings show a marked ontogenetic difference between primary and secondary needles, the latter prevailing with a different timing among species.

? Using the electrolyte leakage method following an artificial freezing test, we aimed at (1) determining the differences in freezing tolerance between primary and secondary needles in eight pines of contrasting thermal habitats: P. canariensis, P. pinea, P. halepensis, P. brutia, P. pinaster, P. nigra, P. sylvestris and P. radiata, (2) evaluating the relation between freezing tolerance and sclerophylly and (3) relating freezing tolerance with the climate of origin.

? Primary needles were significantly more sensitive to freezing than secondary needles in Pinus halepensis, P. brutia, P. pinaster and P. nigra, whereas no differences were found in P. canariensis, P. pinea and P. radiata. LT50 was uncorrelated with needle sclerophylly but very highly correlated with the mean temperature of the coldest month at the seed source.

? Results support an adaptive role of secondary needles in the mountain Mediterranean pines P. nigra, P. pinaster and P. brutia, while the more complex responses in coastal Mediterranean pines can be interpreted in the light of seedling ontogeny and species’ ecological niches.

     

The Effects of Stressful Broodstock Handling on Hormonal Profiles and Reproductive Performance of Rhamdia quelen (Quoy & Gaimard) Females

Abstract.— A stressful environment induces cortisol that might affect fish breeding and reproduction. In the present work, which aimed to mimic aquacultural conditions of the jundia (Rhamdia quelen) hatcheries in southern South America, females were submitted to normal or stressful handling and the effects of cortisol on serum levels of 17β‐estradiol (E2) and testosterone (T) were determined. In addition, the effect of stress on reproductive parameters such as eggs and swim‐up fry production was also measured. Eight females from a group submitted to stressful handling (SH) conditions and eight females from a group with normal handling (NH) conditions were captured for blood sampling at D 0 and at D 1, 10, 20, 30, and 40 of the experiment. A typical cortisol response was observed in the SH females group in that they presented higher cortisol level in contrast to the NH female group, in all days sampled, except at D 0. In the 10th and 20th d, the E2 levels were lower in SH females, but cortisol levels were higher, suggesting an effect of cortisol on E2 production and/or release. Stressful handling appeared to affect both the number and the quality of the gametes because a lower number of oocytes was stripped from SH females, and from SH fertilized eggs, a lower number of viable swim‐up fry was obtained to be transferred to earthen larviculture ponds. Taken together, the results indicated that stressful handling of broodstock impairs R. quelen reproduction.     

Identification of mtDNA lineages of Sus scrofa by multiplex single base extension for the authentication of processed food products

A genetic method to identify the breed of origin could serve as a useful tool for inspecting the authenticity of the increasing number of monobreed foodstuffs, such as those derived from small local European pig breeds. Mitochondrial DNA (mtDNA) is practically the only reliable genomic target for PCR in processed products, and its haploid nature and strict maternal inheritance greatly facilitate genetic analysis. As a result of strategies that sought to improve the production traits of European pigs, most industrial breeds presently show a high frequency of Asian alleles, while the absence or low frequency of such Asian alleles has been observed in small rustic breeds from which highly prized dry-cured and other traditional products are derived. Therefore, the detection of Asian ancestry would indicate nonconformity in Protected Denomination of Origin products. This study presents a single base extension assay based on 15 diagnostic mtDNA single nucleotide polymorphisms to discriminate between Asian and European Sus scrofa lineages. The test was robust, sensitive and accurate in a wide range of processed foodstuffs and allowed accurate detection of pig genetic material and identification of maternal ancestry. A market survey suggested that nonconformity of products derived from Portuguese breeds is an unusual event at present, but regular surveys both in the local populations and in commercial products would be advisible. Taking into consideration the limitations presented by other methodologies, this mtDNA-based test probably attains the highest resolution for the direct genetic test for population of origin in Sus scrofa food products.