Use of Powdered Egg Yolk vs Fresh Egg Yolk for the Cryopreservation of Ovine Semen

Egg yolk is a common additive to sperm cryopreservation diluents. Because of its animal origin, however, it also represents a potential risk of microbiological contamination in the diluent. This potential contamination can be avoided by using powdered egg yolk, instead of fresh egg yolk, as it is pasteurized. This study was conducted to determine ram sperm cryosurvival was affected by the type of egg yolk used (powdered egg yolk or fresh egg yolk) and by yolk concentration (10, 15 or 20%) in the diluent. Microbiological analyses were also performed to quantify the microbiological contamination in the diluents containing the two types of egg yolk. Sperm cryosurvival was determined by motility and morphology analyses after thawing. Motility parameters were assessed using a computer-assisted sperm analysis (CASA) system, and the percentage of sperm with a normal apical ridge was evaluated using a differential interference contrast microscope. No significant differences were observed between diluents in the percentage of sperm with normal apical ridge. However, higher percentages of total motile cells were observed for samples containing powdered egg yolk (69%) compared to samples containing fresh egg yolk (60%). However, sperm in diluents containing fresh egg yolk, exhibited higher values for average-path velocity, straight-line velocity and beat cross frequency and lower values for amplitude of lateral head displacement (p <0.05), compared to cells in diluents containing powdered egg yolk. Microbiological contamination was similar (<200 CFU/ml) in both diluents, and no bacterial growth was observed in either, when antibiotics were added. Therefore, powdered egg yolk can be effective used in diluents for the freezing of ram semen. However, the in vivo fertility of sperm frozen in diluents containing powdered egg yolk should be tested, as some motility parameters were different for sperm treated with powdered egg yolk compared to fresh egg yolk.     

Histopathological findings in farmed rainbow trout (Oncorhynchus mykiss) naturally infected with 3 different Aeromonas species

This study describes the macroscopic and microscopic lesions in farmed rainbow trout (Oncorhynchus mykiss) naturally infected with genetically identified Aeromonas salmonicida, A. hydrophila, and A. veronii species. The genus Aeromonas includes bacteria that naturally inhabit both waterways and organisms. At least 27 Aeromonas species have been identified to date, some of which can cause significant economic losses in aquaculture. As up to 68.8% of Aeromonas isolates may be misidentified in routine biochemical and phenotypic tests, however, reported cases of Aeromonas infection in fish may be wrongly identified. Our findings confirmed that the 3 Aeromonas species studied are associated with septicemia and dermal lesions in rainbow trout.     

Aboveground biomass,transpiration and water use efficiency in eucalypt plantation fertilized with KCl,NaCl and phonolite rock powder

Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha^?1 of KCl compared with that of 2125 kg ha^?1 of phonolite rock powder (equivalent to 170 kg ha^?1 of K₂O in both treatments); (2) application of 139 kg ha^?1 of NaCl compared with that of 183 kg ha^?1 of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.

     

Planktonic foraminifera of the California Current reflect 20th-century warming

It is currently unclear whether observed pelagic ecosystem responses to ocean warming, such as a mid-1970s change in the eastern North Pacific, depart from typical ocean variability. We report variations in planktonic foraminifera from varved sediments off southern California spanning the past 1400 years. Increasing abundances of tropical/subtropical species throughout the 20th century reflect a warming trend superimposed on decadal-scale fluctuations. Decreasing abundances of temperate/subpolar species in the late 20th century indicate a deep, penetrative warming not observed in previous centuries. These results imply that 20th-century warming, apparently anthropogenic, has already affected lower trophic levels of the California Current.     

Competition and interactions among stripe rust pathotypes in wheat-cultivar mixtures

A series of experiments was conducted with wheat stripe rust to analyse competition between simple and complex pathotypes in host mixtures. Two different pathotype combinations were tested, with different host components. Each combination included a complex (able to infect two host components) and two simple pathotypes. For one of the combinations, induced resistance was tested in a separate experiment as a possible interaction among pathotypes. Disease severity and pathotype frequencies were measured three times during the epidemic, on each host component grown in pure stands and in mixtures. In one of the experiments, pathotype frequencies were also measured within secondary foci. One of the complex pathotypes appeared to have a low fitness on one of the host components and did not significantly increase in frequency in host mixtures relative to pure stands. The average frequency of the other complex pathotype increased during the first epidemic cycles, but remained stable afterwards, below expected values. The results suggest that the development of complex pathotypes in host mixtures may be influenced by differential aggressiveness on the host components, by induced resistance and by random effects resulting from the formation of disease foci, and depends on pathogen autoinfection rate and dispersal mechanisms.     

Pharmacokinetics of an ampicillin/sulbactam (2:1) combination in rabbits

The pharmacokinetics of a 2:1 ampicillin-sulbactam combination in six rabbits, after intravenous and intramuscular injection at a single dosage of 20 mg/kg bodyweight (13.33 mg/kg of sodium ampicillin and 6.67 mg/kg of sodium sulbactam) were investigated by using a high performance liquid chromatographic method for determining plasma concentrations. The plasma concentration-time curves were analysed by compartmental pharmacokinetic and noncompartmental methods. The disposition curves for both drugs were best described by an open two-compartment model after intravenous administration and a one-compartment model with first order absorption after intramuscular administration. The apparent volumes of distribution calculated by the area method for ampicillin and sulbactam were 0.62 +/- 0.09 and 0.45 +/- 0.05 L/kg, respectively, and the total body clearances were 0.65 +/- 0.04 and 0.42 +/- 0.05 L/kg h, respectively. The elimination half-lives of ampicillin after intravenous and intramuscular administration were 0.64 +/- 0.11 and 0.63 +/- 0.16 h, respectively, whereas for sulbactam the half-lives were 0.74 +/- 0.12 and 0.77 +/- 0.17 h, respectively. The bioavailability after intramuscular injection was high and similar in both drugs (73.34 +/- 10.08% for ampicillin and 83.20 +/- 7.41% for sulbactam). The mean peak plasma concentrations of ampicillin and sulbactam were reached at similar times (0.20 +/- 0.09 and 0.34 +/- 0.15 h, respectively) and peak concentrations were also similar but nonproportional to the dose of both products administered (13.07 +/- 3.64 mg/L of ampicillin and 8.42 +/- 1.74 mg/L of sulbactam). Both drugs had similar pharmacokinetic behaviour after intramuscular administration in rabbits.     

Evaluation of biological control agents for managing cucurbit powdery mildew on greenhouse-grown melon

An evaluation was made of the ability of two mycoparasite-based products AQ10® ( Ampelomyces quisqualis ) and Mycotal® ( Lecanicillium lecanii ), as well as three strains of Bacillus subtilis , to manage powdery mildew disease, caused by Podosphaera fusca on melon seedlings maintained under different regimes of relative humidity and on plants grown under greenhouse conditions in Spain. In every case fungal and bacterial biocontrol agents (BCAs) performed better under conditions of high relative humidity (90–95% RH). In greenhouse experiments, the effectiveness of the mycoparasites to manage powdery mildew was absolutely dependent on mineral oil. The strains of B. subtilis provided disease control similar to that achieved with the mycoparasites or the fungicide azoxystrobin. Microscopic analysis showed the ability of these bacterial strains to efficiently colonize leaf surfaces and revealed the occurrence of antagonistic interactions between biological agents and P. fusca structures. These results confirmed the usefulness of these BCAs for managing powdery mildew on greenhouse-grown cucurbits either as single products or as a component of integrated control programmes.     

Rapid thin layer chromatographic determination of zearalenone in corn, sorghum, and wheat

A rapid method is described for determining zearalenone in corn, sorghum, and wheat. The mycotoxin is extracted with a mixture of acetonitrile and 4% KCl in HCl. The extract is cleaned up with isooctane, evaporated, and redissolved in chloroform. Zearalenone is separated by thin layer chromatography; identity is confirmed with various developing solvents and spray reagents. Zearalenone is then quantitated by the limit detection method. The minimum detectable concentration is 140-160 micrograms/kg when aluminum chloride solution is used as spray reagent, and 85-110 micrograms/kg when Fast Violet B salt is used as spray reagent.     

Guava decline: effect of root exudates from Meloidogyne enterolobii-parasitized plants on Fusarium solani in vitro and on growth and development of guava seedlings under controlled conditions

In guava decline, Fusarium solani-immune guava trees become susceptible to extensive root rot caused by this fungus after parasitism by Meloidogyne enterolobii. To understand the mechanisms involved in this disease, root exudates were collected from nematode-inoculated (NI) or uninoculated (UN) guava plants cultivated in sand. After filtration through a Millipore® membrane, NI and UN exudates were used: i) to prepare media to assess their effect on mycelial growth and production of propagules of F. solani isolate UENF/CF 163, and ii) to incubate macro- and microconidia to assess their effect on germination. NI exudates promoted (P?<?0.05) more mycelial growth and production of propagules than UN exudates or water. NI and UN exudates were used to water guava seedlings laid over seed germination paper inside plastic boxes. Half of the seedlings had an agar plug colonized by the fungus positioned in the collar region. Upon watering with NI exudates the fungus caused (P?<?0.05) extensive rotting of the seedlings’ rootlets. NI and UN exudates, either unlyophilized or lyophilized and re-suspended to the original concentration, were used to water guava seedlings grown in sterile sand before being inoculated (or left uninoculated) as described before. Solely upon watering with NI exudates, in its unlyophilized form or after lyophilization, the fungus caused a reduction (P?<?0.05) of shoot and root biomass associated with rotting of roots. These results suggest that M. enterolobii induces chemical changes in the root exudates of guava trees, which are necessary for root invasion causing root rotting by F. solani.