The effect of feeding the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on cell-mediated immunity and protection against Yersinia ruckeri in pikeperch (Sander lucioperca)

The present study examined the influence of leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB), a natural product HMB, on nonspecific cell‐mediated defence mechanisms and protection against enteric redmouth disease (ERM) in pikeperch (Sander lucioperca). β‐hydroxy‐β‐methylbutyrate was fed in a pelletted ration at 50 mg kg^?1 of the feed for 8 weeks. The phagocytic ability and potential killing activity of blood and pronephric phagocytes were examined in HMB‐ and control‐fed fish before and after 8 weeks of feeding HMB. Simultaneously, the proliferative response of blood and pronephric lymphocytes stimulated by mitogens concanavaline A and lipopolisaccharide were examined in experimental and control groups. Following 8 weeks of HMB feeding, a challenge test was performed by injecting the fish with live pathogenic bacteria Yersinia ruckeri. β‐hydroxy‐β‐methylbutyrate applied in the diet for 8 weeks prompted a statistically significant (P<0.05) increase in phagocytic ability and potential killing activity of the blood and pronephric phagocytes and the proliferative response of blood and pronephric lymphocytes. The changes in these mechanisms correlated with protection against Y. ruckeri, the ERM pathogen. The results showed that feeding HMB increased the nonspecific cell‐mediated defence mechanisms and protection against ERM by reducing cumulative mortality (30%) following the challenge with pathogenic bacteria. Future studies will include determination of optimal doses and protocols of oral application of HMB to maximize the immunomodulatory effects and protection against viral diseases in intensive pikeperch culture.     

Relationship between biochemical constituents of fish semen and fertility: the effect of short-term storage

Spermatozoa and seminal plasma obtained from rainbow trout and whitefish were analyzed in respect to their aspartate aminotransferase (AspAT) and alkaline phosphatase activities. In particular, the experiments characterized AspAT optimum pH, optimization of assay conditions and action of coenzyme, pyridoxal 5-phosphate (vitamin B₆). The effect of short-term semen storage at 0°C on biochemical indicators and fertilization rate was examined in both species. The concentrations of reduced and oxidized ascorbic acid in seminal plasma of both species were several folds higher than in spermatozoa and blood plasma of fish. Highly significant correlations were found for both species between AspAT activity (sperm or seminal plasma) and fertilization rate (% of eyed-stage or hatched embryos). For rainbow trout, highly significant correlations were found between sperm concentration, motility and fertilization rate. These results suggest that several biochemical indicators of seminal plasma can be used as measures of sperm quality of fish. Some common biochemical parameters for fish and mammal's semen provide evidence for using fish sperm as a model in biomedical research.     

Studies of composition and major protein level in milk and colostrum of mares

The aim of the study was to determine the changes in composition and physicochemical features (pH, density, thermostability and acidity) of mare colostrum and milk, and of protein fraction contribution (serum albumin, β-casein, γ-casein, α-lactalbumin, G class immunoglobulins) depending on lactation stage. The research material was colostrum and milk samples from 12 Arabian mares. Colostrum samples were collected within 2 h after parturition and milk samples were collected twice, in the 3rd and 6th weeks of lactation. The level of basic milk components decreased significantly (only lactose content increased) as compared to colostrum. Total bacteria count and somatic cell count decreased significantly with an increase in resistance and urea level. The changes observed were connected to differentiated contribution of particular protein fractions and their relative proportions. Lower levels of γ-casein (P ≤ 0.05), β-casein, serum albumin as well as α-lactalbumin were observed in colostrum as compared to those in milk. Any relationship between lactation stage and β-casein content was observed. Serum albumin and α-lactalbumin content increased in subsequent milkings. The level of G class immunoglobulins decreased significantly and its highest level was noted in colostrum. Any significant differences between the 3rd and 6th lactation weeks were obtained.     

Dietary resveratrol improves immunity but reduces reproduction of broodstock medaka <Emphasis Type="Italic">Oryzias latipes</Emphasis> (Temminck &amp; Schlegel)

Here, we investigated the effect of dietary resveratrol (20, 40, and 80 µg/g BW/day) on cell-mediated immunity (activity of spleen phagocytes and proliferative response of lymphocytes) and reproductive parameters (egg and sperm quality, i.e. fecundity—total number of eggs produced by individual fish, fertility, embryo survival, and hatching rate) in medaka. Fish fed feed with resveratrol at 40 and 80 µg/g BW/day had significantly higher metabolic activity and intracellular phagocyte killing activity than control. The proliferative lymphocyte activity of the fish from R80 group was greater by more than 20 % in comparison with the control group (P < 0.05). The percentage of macrophages (MO) and their mean fluorescence intensities (MFI) in R40 and R80 groups were significantly higher compared to C and R20 groups (P < 0.05). The differences in MO and MFI values ranged from 52.5 % (±1.5; R0 group) to 65.8 % (±1.6; R80 group) and from 23.2 (±1.4; R0 group) to 38.2 (±2.4; R80 group), respectively. Moreover, resveratrol at 80 µg/g BW/day decreased liver COX activity, i.e. 5.4 in R80 group and 7.9 in R0 group (P < 0.05). The motility parameters of the sperm obtained from the males fed feed supplemented with resveratrol at 80 µg/g BW/day exhibited the highest values except the linearity, which was lower as compared to the control (P < 0.05). The results indicate that diet supplemented with resveratrol at a dosage of 40 µg/g BW/day improves phagocyte killing ability and lymphocyte proliferation in broodstock and accelerates offspring hatch. Also, the results suggest that COX activity influences sperm and oocyte quality in fish; the presence of a COX inhibitor in the dose of 40 µg/g BW/day decreased the embryo survival.     

Fusobacterium necrophorum,and not Dichelobacter nodosus,is associated with equine hoof thrush

The aim of this study was to determine which of the two species, Fusobacterium necrophorum or Dichelobacter nodosus, are associated with hoof thrush in horses. Fourteen hoof samples, collected from eight horses with thrush and 14 samples collected from eight horses with healthy hooves, were examined for the presence of F. necrophorum, Fusobacterium equinum and D. nodosus. Only isolates with phenotypic characteristics representing Fusobacterium could be cultured. Total DNA extracted from the 28 hoof samples was amplified by using DNA primers designed from gene lktA, present in F. necrophorum subsp. necrophorum, F. necrophorum subsp. funduliforme and F. equinum, and gene fimA, present in D. nodosus. The lktA gene was amplified from five of the 14 infected hoof samples and from one hoof sample without thrush. The DNA sequence of the amplified ltkA gene was identical to the lktA gene of the type strain of F. necrophorum (GenBank accession number AF312861). The isolates were phenotypically differentiated from F. equinum. No DNA was amplified using the fimA primer set, suggesting that F. necrophorum, and not D. nodosus, is associated with equine hoof thrush. Hoof thrush in horses is thus caused by F. necrophorum in the absence D. nodosus. This is different from footrot in sheep, goats, cattle and pigs, which is caused by the synergistic action of F. necrophorum and D. nodosus.     

A Comparison of Microbial Community Function and Structure in Rehabilitated Asbestos and Coal Discard Sites

Previous studies have made some progress with the use of microbial community properties as assessment criteria for rehabilitation success of post-mining areas. Currently, there is a need for reference ranges of specific properties in rehabilitated post-mining sites to make this approach more practical. The aim of this investigation was to compare assessment parameters indicative of microbial community function (enzymatic assays) and structure (phospholipid fatty acid (PLFA) analysis) in rehabilitated asbestos and coal discard sites and to establish ranges of minimum and maximum values for these parameters in both types of sites. The range established for dehydrogenase activity in coal discard sites was 24.3–339.5 μg INF g⁻¹ 2 h⁻¹ and for asbestos 44.5–544.6 μg INF g⁻¹ 2 h⁻¹. Ranges were also established for β-glucosidase, urease, acid phosphatase and alkaline phosphatase. Complete PLFA profiles were determined and ranges established for major PLFA groups and ratios in both types of discard. From the PLFA profiles, viable microbial biomass was determined as 6,080–29,851 and 8,128–47,242 pmol g⁻¹ dry weight for the coal and asbestos discard sites, respectively. While similar ranges were observed for both types of discard, a canonical correspondence analysis that accounts for functional and structural characteristics showed that sites clustered according to the origin of the samples.     

Mechanisms for Translocation of Heavy Metals from Soil to Epigeal Mosses

The mechanisms for translocation of heavy metals from soil to epigeal mosses were investigated. The first mechanism was demonstrated for ¹³⁷Cs and involved the uplifting of the pollutant-containing dust from the soil, followed by the local secondary deposition on surfaces of epigeal mosses and epiphytic lichens. The second mechanism involved the diffusion of metal cations from the soil through water wetting the moss into the gametophyte. The mechanism was demonstrated by measuring the electric conductance of wetted gametophytes with single ends immersed in solutions of Cu and Na salts. In addition, the concentrations of Cu and Cd were compared in moss samples exposed to the natural soil and to the soil contaminated with the metals. The exposition to the contaminated soil resulted in the statistically significant increase of metal concentrations in the gametophytes.     

Citrus flavanones: what is their role in cardiovascular protection?

Flavanones, including hesperidin and naringin, are polyphenolic compounds highly and almost exclusively present in citrus. Epidemiological studies reported an inverse relationship between their intake and the risk of cardiovascular diseases. Clinical and experimental data further showed their antihypertensive, lipid-lowering, insulin-sensitizing, antioxidative, and anti-inflammatory properties, which could explain their antiatherogenic action in animal models. Although flavanones may be promising compounds that are particularly active in cardiovascular disease prevention, clinical data are still scarce and most in vitro data have been obtained under nonphysiologically relevant conditions. Moreover, the mechanisms responsible for flavanone action are not fully elucidated. Therefore, further research is needed to better evaluate and understand the protective effects of flavanones in cardiovascular diseases.     

Anionic relationships in leaf petiole sap of tomato and capsicum plants growing in a glasshouse

The nitrate, chloride and sulphate content and their interaction effects in capsicum and tomato plants growing in glasshouse under fertigation systems was studied. Using leaf petiolesap concentrations as an index of the uptake rhythm, it was found that nitrate‐chloride and nitrate‐chloride plus sulphate relationships are regulated by potential or logarithmical laws. Nitrate‐sulphate interactions only appear clear in capsicum plants, but not for tomato.

The utilization of these interaction curves may permit the use of waters with a relatively high saline level for the irrigation of the both capsicum and tomato plants, by suitable planning of the nitrate supply in the fertigation program.