Effects of various diet formulations (experimental and commercial) on the morphology of the liver and intestine of rainbow trout (Oncorhynchus mykiss) juveniles

The aim of the present study was to evaluate the effects of three formulated diets: wheat gluten protein‐based diets supplemented with Lys–Gly dipeptide (PP) or free lisine and glycine (AA), and a control diet without lysine supplementation (CON), two commercial starters: Aller Futura (AF), Aglo Norse (AN) and frozen Chironomidae larvae (CH) for on the growth and digestive system development of rainbow trout. The experiment lasted 28 days and survival at the end of the experiment was the highest in the group fed AF (87.9±4.2%) and the lowest in the group fed the CON diet (74.0±4.3%). Fish fed the CON diet showed a significantly lower crude protein content, and the AA group had a significantly higher lipid level (P≤0.05) in body carcass compared with the other groups. The highest density of intestinal goblet cells (P≤0.05) was observed in fish fed the CON diet, while the lowest density was seen in the distal intestine in the AF group. The hepatocyte cytoplasm of all fish stored more glycogen than lipids. These results indicate that wheat gluten protein‐based diets supplemented with dipeptide Lys–Gly (PP) or free lysine and glycine (AA) supported growth, protein efficiency rate and intestine epithelium homeostasis. On the other hand, fish fed CON (lysine‐deficient diet) showed lower survival and growth rate, and disturbances of intestine epithelium homeostasis, probably as a result of lysine deficiency.     

Increased intensity of tert-butoxyl radical emission in 4-chloro-2-methylphenoxyacetic acid (MCPA) synthesis

The important herbicide, 2-methyl-4-chlorophenoxyacetic acid (MCPA) was synthesized by the chlorination of 2-methylphenoxyacetic acid with tert-butyl hypochlorite in the presence of methyl N,N-dimethylglycinate as a catalyst, giving a high yield and regioselectivity. The reaction was investigated using the spin-trapping technique in electron paramagnetic resonance measurement conditions, with nitrosodurene as a spin trap. Increased intensity emission of the tert-butoxyl radical (2.9 times in relation to the starting level) was observed after the catalyst had been introduced into the reaction mixture, indicating a free radical mechanism for the reaction. © 1999 Society of Chemical Industry     

The Impact of Acid Rain on Potassium and Sodium Status in Typical Soils of the Wielkopolski National Park (Poland)

A previous investigation of thechemical characteristics of precipitation in theWielkopolski National Park has shown its high acidity,which sometimes drops below pH 3.0. This paper dealswith the leaching of potassium and sodium ions by acidrain from typical soils of the study area. Laboratoryexperiments were conducted on undisturbed soil cores(15 cm in diameter, 50 cm high) with acid solutions of pH 3.0, pH 2.0 and with water of pH 5.6 (control). The sprinkling lasted 30 days simulating a rainfall of 400 mm. The eluates were analysed daily. Soil propertiesand forms of potassium and sodium were determinedbefore and after treatment. The investigations showthat quite significant amounts of K⁺ andNa⁺ can be leached from the soil: in the very acidtreatment (pH 2.0) about 4 mg K⁺ and 3 mgNa⁺ per kg of soil. The leaching of these elementswas smaller in the pH 3.0 and 5.6 treatments.Differences in the dynamics of the process are shownin the leaching curves. In the case of potassium theirshapes are smooth when pH is 5.6 and 3.0, while at pH2.0 the curves rise sharply. The leaching curves inthe case of sodium do not show sharp peaks, whichmeans that the leaching is slow and equalised.     

Aluminium and iron oxides affect the soil structure in a long-term mineral fertilised soil

Journal of Soils and Sediments - The influence of iron and aluminium (hydr)oxide on soil aggregation is still not sufficiently understood. Therefore, we undertook a study on the effects of Al and...     

The distribution of sequentially extracted Cu,Pb, and Zn fractions in Podzol profiles under dwarf pine of different stages of degradation in subalpine zone of Karkonosze Mts (central Europe)

Journal of Soils and Sediments - Here, we aimed to assess the contamination of Podzol soils in a subalpine zone of the Karkonosze Mountains. Cu, Pb, and Zn concentrations in the soil and the...     

Regeneration patterns of the late-successional <Emphasis Type="Italic">Abies alba</Emphasis> Mill.: inhibition in monospecific stands and colonization in mixed stands

Key message

In Abies alba Mill. stands and mixed stands of A. alba and Picea abies L. (H. Karst), microsites neighbouring the trunks of adult trees were more conducive to A. alba regeneration. Although at the stand level, the effect of Fagus sylvatica L. was positive; the local effect of the adult F. sylvatica neighbourhood was insignificant. Hence, forming mixed stands with a fine-grained mosaic of admixed species might better facilitate natural regeneration of A. alba than monospecific stands.

Context

The establishment of natural regeneration in Abies alba Mill. stands is a slow, spatially heterogeneous and stochastic process. Recent studies based on inventory data indicate that A. alba more readily regenerates in mixed stands than in monospecific stands.

Aims

The objective was to examine how this positive association evidenced at the stand level operates on the scale of microsites with contrasting local species composition and stand density.

Methods

In 8 monospecific and 22 mixed stands with Fagus sylvatica L. or Picea abies L. (H. Karst), microsites with a contrasting density of A. alba seedlings were selected and compared in terms of local species composition, stand density, canopy characteristics and topsoil properties.

Results

In A. alba stands, seedling density was positively associated with the proximity of adult trees. In mixed stands of A. alba and P. abies, adult trees of both species exerted a positive effect on A. alba regeneration, but the P. abies neighbourhood influenced regeneration occurrence more strongly than the A. abies neighbourhood. In mixtures with F. sylvatica, however, the effect of local stand density and local species composition was not evidenced at all.

Conclusion

Although at the stand level, P. abies and F. sylvatica exert a positive effect on A. alba regeneration, on the microsite scale, their influences differ. In stands with a dominance of A. alba, the hampered seedling establishment in gaps may be considered an inhibitive effect that facilitates the emergence of other species.

     

Distribution of stresses in finger joints

Summary This paper presents results of theoretical and experimental studies determining distribution of stresses in connected elements and the glue bond of the finger joint. In cross sections away from the beam joint, it was found that the distribution of stresses was consistent with the theory of the strength of materials. However, in the joint itself, there are irregularities in the distribution of tangential and normal stresses. These inconsistencies are bigger in the orthotropic solid than in the isotropic one. The dramatic stress distribution in the adherend also affected variations in the distribution of tangential stresses in the adhesive bond. Mean tangential stresses in the bond do not exceed the shear strength of the glue due to large surfaces of joining elements. However, concentrations of tangential stresses at bond's ends cause that acceptable stresses for the glue are exceeded. The general theory of strength of materials describes the state of stresses in the adhesive bond correctly only in the case of the isotropic solid.     

Resistance to powdery mildew in selections from Moroccan barley landraces

Seventy-five barley landraces from Morocco were tested for resistance to powdery mildew and a number of different resistance genes were detected. Thirty-five isolates of Blumeria graminis f. sp. hordei and the Pallas isoline differential set were used. Isolates used in the experiment had virulences corresponding to all major resistance genes used in Europe. Forty-four of the tested landraces showed resistant reactions. From each of these landraces, one to five resistant plants were selected and 92 single plant lines were created. Six lines selected from 3landraces were assumed to carry the mlo gene but they were discarded after microscopic investigation. Seventeen lines were tested in the seedling stage with 17isolates and another 69 lines were tested with 23 differential isolates. These lines showed 71 reaction spectra to isolates of powdery mildew. Eight lines (9%), 255-3-3, 282-3-4, 286-1-1, 294-2-3,294-2-4, 295-1-2, 308-1-2 and 327-2-1, selected from 7 landraces showed resistance to all isolates. Seventy-eight lines (90%) showed a resistant infection type 2with more than 50% of the isolates used. In most of the selected lines (86%) unknown genes, alone or in combination with known specific resistance genes, were detected. Four different resistance alleles (Mlat, Mla6, Mla14 and Mla1) were postulated to be present in the tested lines. The most common was Mlat, which was postulated in 35 (41%) lines. The use of newly identified sources of powdery mildew resistance in barley breeding is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Morphology of the inferior pharyngeal bones of white bream (Blicca bjoerkna) in River Warta

The inferior pharyngeal bones are a characteristic feature of the Cyprinidae. Morphology of inferior pharyngeal bones is important in the diagnosis of carnivorous food, or determining the diet of fishes. Due to the lack of literature data, the aim of the study was to examine the morphology of the inferior pharyngeal bone in detail. 102 Blicca bjoerkna specimens caught in the River Warta (Poland) were analysed. 204 inferior pharyngeal bones were collected. The parameters of the inferior pharyngeal bones correlated with the measured head features and the total fish length. The arches of inferior pharyngeal bones did not have directional asymmetry for the two main parameters (height and width of inferior pharyngeal bone). However, there was a left‐sided directional asymmetry of the ventral part of inferior pharyngeal bone. In the case of the B. bjoerkna from River Warta, large differences in terms of individual parameters of inferior pharyngeal bones were observed. Fluctuation asymmetry was low. Shape of inferior pharyngeal bones was very round. In total, 12 teeth formulas were described. The 35.29% of the fish had formula different than described in the literature 2.5–5.2 and more teeth in the right arches. Following identification, measurements of the structures enable estimation of the lengths and weights of prey to be determined from biometric relationships. Analysis of body morphological features in combination with pharyngeal bone morphology could show a hybrid in the Warta river's population.