Stable isotopes and gut contents indicate differential resource use by coexisting asp (Leuciscus aspius) and pikeperch (Sander lucioperca)

Differential use of habitat and prey resources is an important mechanism that may allow coexistence of sympatric species. Unlike interactions between smaller cyprinid and percid fishes, the resource use by coexisting predatory asp (Leuciscus aspius) and pikeperch (Sander lucioperca) is relatively unknown. Here, gut content and stable isotope analyses were used to study ontogenetic dietary shifts and interspecific trophic niche overlap between asp and pikeperch coexisting in two reservoirs. The hypothesis that both species show an ontogenetic dietary shift from small invertebrates to large fish prey, but at the same time use different prey resources to reduce potential competitive interactions, was validated. The isotopic niches of the two predators showed no, or only a moderate, degree of overlap (0%–65%). The ontogenetic changes in the degree of interspecific isotopic niche overlap were different in the two reservoirs, suggesting that trophic segregation can be dynamic and variable among systems. Gut contents revealed that small (<100 mm standard length) asp consumed mostly terrestrial invertebrates and emerged aquatic insects, whereas small pikeperch foraged on zooplankton, larval and pupal stages of aquatic insects and fish. Larger individuals (>100 mm) of both species were predominantly piscivorous, with asp consuming more cyprinid prey and pikeperch more percid prey. Coexisting asp and pikeperch populations are able to utilise different prey resources, thereby reducing potential negative competitive interactions.     

Genetic diversity within sea trout population from an intensively stocked southern Baltic river,based on microsatellite DNA analysis

Sea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small‐scale differentiation in sea trout populations from one basin with a strong emphasis on the relationship between wild and hatchery origin fish. A total of 216 sea trout were genotyped at 10 microsatellite loci. Global F_ST obtained by amova was low at 0.0165. Pairwise F_ST were significant for all tests except wild and stocked adults. The highest pairwise difference was found between the hatchery sample and Kwacza (F_ST = 0.038). Analysis of the genetic structure revealed micro‐geographical differentiation with four subpopulations. The quality of the artificial spawning was found not to be adequate with a high risk of adverse effects to the whole population. All future stocking actions in the basin should consider the existing population structures.     

Exocrine pancreatic secretion in pigs fed sow's milk and milk replacer, and its relationship to growth performance

The objective of this study was to quantify and compare the effects of sow's milk and 2 milk replacer diets (containing clotting or non-clotting protein sources) on exocrine pancreatic secretion, plasma cholecystokinin, and immunoreactive cationic trypsin in pigs. In addition, the relationship between exocrine pancreatic secretion and growth in milk-fed pigs was studied. In a changeover experiment, 9 chronically catheterized pigs of 6.6 +/- 0.19 kg of BW were studied for 3 wk. Pigs were assigned to each of 3 diets. Exocrine pancreatic secretion was measured from the third to the seventh day on each diet. The protein content and trypsin activity of the pancreatic juice were measured. Blood samples were taken at 10 min before and after milk ingestion and were analyzed for cholecystokinin and immunoreactive cationic trypsin. Pancreatic protein and trypsin secretion did not differ between pigs fed sow's milk and those fed milk replacer, but the volume secreted was less for the pigs fed sow's milk (0.75 vs. 1.03 mL x kg(-1) x h(-1); P < 0.01). A postprandial response to milk intake was not observed. The 2 milk replacer diets did not affect exocrine pancreatic secretion differently. The average exocrine pancreatic secretion (volume, 0.94 mL x kg(-1) x h(-1); protein, 4.28 mg x kg(-1) x h(-1); trypsin, 1.65 U x kg(-1) x h(-1)) was intermediate between literature values for suckling and weaned pigs. Plasma cholecystokinin was elevated (approximately 18 pmol x L(-1)) and showed low correlations with the pancreatic secretion traits. Plasma immunoreactive cationic trypsin was not significantly related to any of the pancreatic secretion traits and should therefore not be used as an indicator for exocrine pancreatic function in milk-fed pigs. Exocrine pancreatic secretion varied substantially among individual pigs (protein, 0.22 to 13.98 mg x kg(-1) x h(-1)). Pancreatic protein and trypsin secretion showed a positive, nonlinear relationship with performance traits. It was concluded that neither specific sow's milk ingredients nor the protein source are responsible for a low pancreatic protein secretion in suckling pigs. Exocrine pancreatic secretion was positively correlated with ADG in pigs at an identical milk intake.     

Effect of micronized pea seeds (Pisum sativum L.) as a substitute of soybean meal on tissue fatty acid composition and quality of broiler chicken meat

This study aimed to evaluate the effect of micronized pea seeds introduced into feed mixes for broilers on the slaughter yield, blood lipid parameters, content of fatty acids in selected tissues, and meat quality. The studies involved 150 1‐day‐old Ross 308 chicks split into three groups (for 42 days). The feed rations differed in terms of the source of proteins: in the control group (C), it was post‐extraction soybean meal (SBM) 100%; in group I, SBM 50% and micronized peas 50%; and in group II, micronized peas only, 100%. Irradiated pea seeds added to the feed ration for chicks reduced the fattening grade of carcasses (P < 0.05). Additionally, significant improvement of blood lipid indices was recorded. The share of the irradiated pea seeds in feed mixes decreased the share of saturated fatty acids in the muscles and abdominal fat and had a positive effect on the n‐6/n‐3 ratio, hypocholesterolemic / hypercholesterolemic ratio, as well as the atherogenic and thrombogenic indices (P < 0.05).     

Preparation of biologically active monomeric recombinant zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) and rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) recombinant growth hormones

Fish growth hormones (GHs) play an important role in regulating growth, metabolism, reproduction, osmoregulation, and immunity and have thus garnered attention for their application in aquaculture. Zebrafish GH (zGH) cDNA or rainbow trout GH (rtGH) cDNA was cloned into the pMon3401 vector, expressed in MON105-competent Escherichia coli and purified to homogeneity. Their biological activity was evidenced by their ability to interact with ovine GH receptor extracellular domain and stimulate GH receptor-mediated proliferation in FDC-P1-3B9 cells stably transfected with rabbit GH receptor. The relative affinity of zGH and rtGH, estimated by IC₅₀, was about 38-fold and 512-fold lower, respectively, than ovine GH. This is likely the reason for the low biological activity in cells with rabbit GH receptor, ~?36-fold lower for zGH and ~?107-fold lower for rtGH than for human GH. This was not due to improper refolding, as evidenced by circular dichroism analysis. Predicting the activity of fish GHs is problematic as there is no one single optimal in vitro bioassay; heterologous assays may be ambiguous, and only homologous assays are suitable for measuring activity.     

Rapid de-adhesion of northern pike <Emphasis Type="Italic">Esox lucius</Emphasis> eggs using sodium hypochlorite

The elimination of egg stickiness is required for effective artificial reproduction of northern pike, but until now, available methods have required at least 40 min. Sodium hypochlorite was tested under laboratory conditions, and exposure to aqueous concentrations of 0.025–0.05% for 40 s effectively eliminated stickiness without adverse effects. Fertilization and hatching rates in laboratory trials were similar to those observed in eggs treated with traditional methods using clay or milk for 40 or 60 min, respectively, as well as those without treatment. Testing using conventional hatchery incubation techniques did not reveal differences in fertilization rates, while the number of hatched larva was significantly higher in eggs treated with sodium hypochlorite vs. clay. Eggs treated with sodium hypochlorite retained transparency, which facilitated monitoring of embryo development.     

Comparative Study of Predominant Phytochemical Compounds and Proapoptotic Potential of Broccoli Sprouts and Florets

The study compares lyophilized broccoli sprouts and florets in terms of their chemical composition, cytotoxic and proapoptotic potential against hepatocellular carcinoma HepG2, colorectal cancer SW480, and skin fibroblast BJ cells. Sinapic and isochlorogenic acids were predominant phenolics in the sprouts and florets, respectively. The amount of sulforaphane in the sprouts was significantly higher vs. florets. Oleic and linoleic acids dominated in the sprouts, while caproic, stearic and oleic acids in the florets. Broccoli sprouts were selectively cytotoxic on HepG2 and SW480 cells, with proapoptotic effect for the latter, while the florets were less selective, but more active, with profound proapoptotic effect for HepG2 cells (77.4%). Thus, lyophilized broccoli sprouts may be effectively used in dietary chemoprevention.     

Maize Voc Induction after Infection by the Bacterial Pathogen,Pantoea ananatis,Alters Neighbouring Plant Voc Emissions

Journal of Plant Diseases and Protection - Plants induce volatile organic compounds (VOCs) after pathogen infection and exposure to a neighbouring infected plant. In a greenhouse, we measured VOCs...