Characteristics of monoclonal antibodies against Piscirickettsia salmonis

A panel of 28 monoclonal antibodies against Piscirickettsia salmonis was produced using a purified fraction of the bacterium. To determine their specificity to the pathogen, the antibodies were assayed by ELISA and indirect immunofluorescence microscopy. Six monoclonal antibodies were selected based on their strong reaction against P. salmonis and absence of cross-reactivity with other common fish pathogens. Western blot analysis showed that the antibodies reacted to several antigens of P. salmonis . Immunofluorescence assays revealed that these antibodies reacted with the same specificity to different isolates of P. salmonis obtained from the south of Chile. This panel of monoclonal antibodies represents an important tool to develop simple, rapid, sensitive and highly specific methods for the detection of the pathogen and diagnosis of the disease.     

Effects of crushed conspecifics on growth and survival of Penaeus monodon Fabricius post larvae

In the present study, the hypothesis tested was that Penaeus monodon post‐larvae (PL) experience lower growth when exposed to crushed conspecifics, which was achieved by exposing individual P. monodon PL with abundant food for 4 weeks to a gradient from 0 to 100 crushed conspecific PL L^?1. Both dry weight (48.5±7.2 mg) and body size (28.0±1.3 mm) of animals exposed to 1 macerated PL L^?1 were significantly (P≤0.011) higher than those of animals in treatments with 0, 5 and 10 crushed PL L^?1 (average over treatments: 25.6±3.2 mg; 23.4±0.5 mm). All animals died within 1 week when exposed to 70 and 100 crushed PL L^?1, and within 3–4 weeks when exposed to 50 and 30 crushed PL L^?1. Exposure time affected mortality and it appeared that LC₅₀ values decreased from 60 to 13 crushed PL L^?1 from 1 to 4 weeks' exposure. Survival of P. monodon PL was negatively correlated to pH, biological oxygen demand, ammonia and nitrate. In conclusion, low dose of crushed conspecifics has a stimulatory effect on P. monodon PL, as larvae were heavier and larger, while high doses cause high mortality.     

Impact of diets varying in dietary fibre characteristics on gastric emptying in pregnant sows.

The effects of feeding two fibre-rich diets with contrasting solubility and a concentrated low dietary fibre on the rate of gastric emptying were examined in six gastric cannulated pregnant sows. Additionally, it was examined whether any effect could be related to the physico-chemical properties of digesta, i.e. viscosity and/or water binding capacity. The sows were fed each diet for one week in a 3 x 3 Latin Square design and the samples were taken in a randomised order 0.5, 1, 2, 3, 5 and 15.5 h after the morning meal. The stomach contents were evacuated through the gastric cannula once daily. The evacuated gastric digesta was quantified and a representative sample was taken to determine its viscosity, water binding capacity and its content of dry matter, dietary components and solid (Cr2O3) and liquid (polyethylene glycol) phase markers. The flow of liquid digesta was calculated as the difference between digesta and dry matter. Increasing the content of dietary fibre in the diet led to higher recovery of liquid digesta but did not have any significant effect on the gastric emptying of dry matter and dietary components. The effect of dietary fibre could not be attributed to the viscosity of the liquid phase of digesta but might be related to the ability of the increased gastric dietary fibre content to hold water. The stomach selectively retained the insoluble dietary fibre components most noticeably seen with the bran-supplemented diet where the concentration of insoluble NSP in digesta increased significantly from 2 hours and onward.     

Haptoglobin and pig-major acute protein are increased in pigs with postweaning multisystemic wasting syndrome (PMWS)

The objective of this study was to determine the serum concentration levels of selected acute phase proteins (APP), haptoglobin (HPT) and pig-major acute phase protein (pig-MAP), in postweaning multisystemic wasting syndrome (PMWS) affected pigs and PCV2-subclinically infected pigs. In a first study, a group of 15 eight-week-old conventional pigs from a PMWS affected farm were bled and a complete necropsy, histopathology and in situ hybridisation to detect PCV2 were performed. Based on the results, pigs were classified as suffering from PMWS (n = 10) or healthy animals (n = 5). In a second study, a group of 45 pigs from another PMWS affected farm were selected and bled at 3, 7, 12 and 28 weeks of age. The assessment of PCV2 infection status in these pigs was retrospectively done by PCV2 PCR in serum samples. Selected APP were measured in the serum of all studied pigs by means of radial immunodiffusion. Mean HPT and pig-MAP levels were significantly increased (p = 0.004 and p = 0.0006 respectively) in PMWS-affected pigs when compared to levels found in healthy pigs (2.52 +/- 0.88 mg/mL vs. 1.06 +/- 0.73 mg/mL for HPT and 3.81 +/- 1.53 mg/mL vs. 0.76 +/- 0.34 mg/mL for pig-MAP). In the second study, no significant difference in mean HPT and pig-MAP values were observed between PCV2 PCR positive and negative pigs of any age. However, both APP increased significantly with age in PCV2 PCR negative pigs. Altogether, the present results suggest that APP levels are significantly increased in pigs that develop PMWS, but not in animals with a PCV2 subclinical infection.     

Influence of micro-oxygenation treatment before oak aging on phenolic compounds composition, astringency, and color of red wine

Micro-oxygenation is usually applied to red wines as a cheaper alternative to oak aging. It has been suggested, however, that micro-oxygenation can also be used to complement oak aging in order to improve the quality of very astringent and herbaceous red wines. In this paper we study how applying the micro-oxygenation technique before oak aging affects the composition and quality of astringent red wines. When this technique is applied prior to oak aging, the wines have a slightly less intense red color and significantly higher levels of combined and free anthocyanins and ethyl-bridged anthocyanin-flavanol pigments. On the other hand, no differences in other newly formed pigments are found. Applying micro-oxygenation before oak aging does not affect the total proanthocyanidin concentration, but it produces wines with a slightly (though significantly) higher mean degree of proanthocyanidin polymerization and a drastically lower astringency. These wines also present a clearer impact of wood aromas.     

Unraveling the life history of successful invaders

Despite considerable current interest in biological invasions, the common life-history characteristics of successful invaders remain elusive. The widely held hypothesis that successful invaders have high reproductive rates has received little empirical support; however, alternative possibilities are seldom considered. Combining a global comparative analysis of avian introductions (>2700 events) with demographic models and phylogenetic comparative methods, we show that although rapid population growth may be advantageous during invasions under certain circumstances, more generally successful invaders are characterized by life-history strategies in which they give priority to future rather than current reproduction. High future breeding expectations reduce the costs of reproductive failure under uncertain conditions and increase opportunities to explore the environment and respond to novel ecological pressures.     

Occurrence of the Microcystins MC-LW and MC-LF in Dutch Surface Waters and Their Contribution to Total Microcystin Toxicity

Microcystins (MCs) are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is most abundant and mostly used for risk assessments. As little is known about the presence of these two variants in The Netherlands, we determined their occurrence by analyzing 88 water samples and 10 scum samples for eight MC variants ((dm-7-)MC-RR, MC-YR, (dm-7-)MC-LR, MC-LY, MC-LW and MC-LF) by liquid chromatography with tandem mass spectrometry detection. All analyzed MC variants were detected, and MC-LW and/or MC-LF were present in 32% of the MC containing water samples. When MC-LW and MC-LF were present, they contributed to nearly 10% of the total MC concentrations, but due to their suspected high toxicity, their average contribution to the total MC toxicity was estimated to be at least 45%. Given the frequent occurrence and possible high toxicity of MC-LW and MC-LF, it seems better to base health risk assessments on the toxicity contributions of different MC variants than on MC-LR concentrations alone.     

Hepatitis E virus infection dynamics and organic distribution in naturally infected pigs in a farrow-to-finish farm

The objective of the present study was to determine the pattern of Hepatitis E virus (HEV) infection in a naturally infected, farrow-to-finish herd. For that purpose, a prospective study was conducted in randomly selected 19 sows and 45 piglets. Blood samples were collected from sows at 1 week post-farrowing and from piglets at 1, 3, 6, 9, 12, 15, 18 and 22 weeks of age. Furthermore 3 or 5 animals were necropsied at each bleeding day (but at 1 week of age), and serum, bile, liver, mesenteric lymph nodes and faeces taken. HEV IgG, IgM and IgA antibodies were determined in serum and viral RNA was analysed in all collected samples by semi-nested RT-PCR. Histopathological examination of mesenteric lymph nodes and liver was also conducted. From 13 analysed sows, 10 (76.9%) were positive to IgG, one to IgA (7.7%) and two to IgM (15.4%) antibodies specific to HEV. In piglets, IgG and IgA maternal antibodies lasted until 9 and 3 weeks of age, respectively. IgG seroconversion occurred by 15 weeks of age while IgM and IgA at 12. On individual basis, IgG was detectable until the end of the study while IgM and IgA antibody duration was of 4-7 weeks. HEV RNA was detected in serum at all analysed ages with the highest prevalence at 15 weeks of age. HEV was detected in faeces and lymph nodes for the first time at 9 weeks of age and peaked at 12 and 15 weeks of age. This peak coincided with the occurrence of hepatitis as well as with HEV detection in bile, liver, mesenteric lymph nodes and faeces, and also with highest IgG and IgM OD values at 15 weeks. Finally, different HEV sequences from this farm were obtained, which they clustered within 3 different groups, together with other Spanish sequences, all of them of genotype 3. Moreover, the present study also indicates that the same pig can be infected with at least two different strains of HEV during its productive life. This is the first study characterizing HEV infection in naturally infected pigs with chronological virus detection and its relationship with tissue lesions throughout the productive life of the animals.