Search

European catfish (Silurus glanis L.) is a large predatory fish native to an extensive area in Europe. It has been introduced to its western and southern parts, where it is considered an invasive species with a negative impact on native fishes. European catfish is a territorial species exhibiting site fidelity. Cold water in winter usually leads catfish to exhibit notably low activity. Nevertheless, our telemetric study on 19 juvenile individuals of S. glanis provides information on their unexpected high activity and displacement in winter. Our data reveal that these behavioural changes were caused by oxygen deficiency. Our data also indicate that oxygen deficits may induce migrations of this species.

The private stocking of ornamental crayfish in garden ponds was discussed in previous studies, but there is a lack of detailed analysis for better understanding of this introduction pathway. The Czech Republic is one of leading EU countries in trade with ornamental crayfish and private garden ponds are popular among people. The crayfish keepers in the country were interviewed by self-administered questionnaire to gather data about principal characteristics of the keepers and detailed information about crayfish breeding that are of interest for conservation managers. Besides of releasing crayfish into garden ponds, alarming illegal behavior such as releasing of juvenile crayfish into the wild, and capturing of indigenous crayfish from wild populations, were registered. Therefore focusing on public education to increase awareness of possible unwanted consequences of crayfish release and introduction of an obligation to inform customers about hazardousness of non-indigenous crayfish species for retailers and wholesalers is recommended.

The question was whether a canyon-shaped reservoir is inhabited by genetically distinct populations of European perch Perca fluviatilis exhibiting different spatial behaviour, or by a single population. The study was conducted in the spring of 2006 at Římov Reservoir, Czech Republic. Epipelagic and bathypelagic perch fry ( EPF and BPF) were captured by trawl net (mesh size 1 × 1.35 mm) controlled by echo sounder, and littoral perch fry and adults ( LPF and LPA) were caught by electrofishing and beach seine (mesh size 1 × 1.35 mm). DNA was isolated in 266 individuals from the reservoir, and phylogenetic analysis based on mt DNA was performed ( n = 18) on BPF, EPF, LPF, and LPA from the reservoir and additional sequences from Central Europe. Six microsatellites were used for differentiating among communities ( n = 266). There was no evidence for genetic divergence in mt DNA sequences. Analyses of microsatellites revealed no statistically significant variations between spatial communities, and confirmed genetic homogeneity among communities. FST values and the number of genetic clusters point to the same conclusion, i.e., the reservoir is inhabited by a single population whose individuals occupy different microhabitats. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, records on the occurrence of the Japanese ginbuna Carassius langsdorfii from northern Germany, north-western Italy and southern Bosnia and Herzegovina are presented. The new findings, in addition to former studies reported in the Czech Republic and Greece, show that C. langsdorfii is much more widespread in Europe than was previously believed. [ABSTRACT FROM AUTHOR]

Diethyl phthalate (DEP) has been widely used as a plasticiser in various consumer products, including cosmetics, personal care items, and pharmaceuticals, and recent studies reported a higher abundance of this priority phthalate in the aquatic environment. DEP is a potential endocrine disruptor, affecting immune systems in humans and wildlife even at low-level chronic exposure. As concern over phthalates increases globally, regulatory bodies focus more on their environmental impact. However, limited research is available, particularly using model organisms like planarians. Planarians are ideal for toxicological studies and may provide insightful information on pollutants' neurotoxic, developmental, and ecological effects, especially in freshwater environments where planarians play a vital role in ecosystem balance. Therefore, the objective of the current study was to examine the toxicity of DEP using the freshwater Dugesia sp., as an experimental animal. The LC 50 for the test organism was calculated using DEP concentrations of 800, 400, 200, 100, and 50 µM, with an estimated LC 50 of 357.24 µM. Furthermore, planarians were exposed to sub-lethal DEP concentration (178.62 µM) for one day as well as eight days to evaluate the impact of DEP on planarian locomotion, feeding behaviour, and regeneration ability. At sub-lethal concentration, locomotion and feeding ability were decreased, and regeneration was delayed. Furthermore, neuro-transmittance in planaria was altered by sub-lethal DEP concentration, as indicated by a reduced acetylcholinesterase (AChE) activity. DEP exposure induced oxidative damage in the tested planarians as shown by a marked increase in stress biomarkers, including lipid peroxidation levels and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and glutathione S-transferase (GST). Our study revealed that DEP exposure may prove fatal to freshwater organisms, such as planarians. The observed alterations in behaviour and regeneration ability demonstrate the severity of the effects exerted by DEP as a toxicant in aquatic ecosystems, thereby indicating the need to restrict its usage to protect aquatic environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Multiple species of the elephant fishes (Mormyridae) commonly coexist in sympatry in most African tropical rivers and lakes. In this study, we investigated the trophic ecology and potential trophic niche partitioning of eleven mormyrid fish species from the Sanaga River system in Cameroon using the stable isotope composition of carbon and nitrogen in the muscle samples. Albeit most mormyrids mainly feed on invertebrates, we found differences in isotope ratios, and we report signs of the trophic niche partitioning among species. We further found significant differences in isotopic signatures within the Mormyrus genus, suggesting ecological niche diversification among three closely related species. We have also evaluated differences in the isotopic signals between seasons in four species, which could be possibly caused by species migration and/or anthropogenic agricultural activities. To evaluate body shape, we applied geometric morphometric analyses, and we show that most of the species are clearly morphologically separated. We focused on the mormyrid ecomorphology to identify a possible interaction between shape and ecology, and we found a relationship between the δ 13 C (but not δ 15 N) isotopic signal and morphology, suggesting their interplay during mormyrid evolution. Overall, we present robust evidence of the trophic niche partitioning within the mormyrid species community, and we integrate trophic ecology with morphometrics, shedding light on the enigmatic evolutionary history of these fascinating African fishes., Competing Interests: The authors declare no conflict of interests., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

The trichostrongylid roundworms of the genus Cooperia , which are important in veterinary medicine, currently comprise 19 valid species that parasitize the small intestine of both free-living and domestic ruminants. Only four Cooperia spp. have been reported in Europe, namely C. oncophora, C. punctata, C. curticei and C. pectinata . In 2018-2022, 25 red deer ( Cervus elaphus ) and 30 sika deer ( Cervus nippon ) of both sexes and various ages from several remote locations in the Czech Republic were parasitologically examined. Intestinal nematodes of the genus Cooperia were found only in two northern regions. Using the globally recognized key book on trichostrongylid nematodes, they were preliminarily identified as C. pectinata . However, a molecular analysis of cox 2 and ITS rDNA gene sequences revealed that Cooperia sp. parasitizing Czech deer is a separate taxon that is more closely related to C. oncophora than to C. pectinata . A subsequent morphological analysis and literature survey confirmed the independence of deer Cooperia sp., which is similar but not identical to bovid C. pectinata . Previous long-term correct identifications of bovid C. pectinata and misidentifications of deer Cooperia species were caused by a fundamental error in the key book mentioned above. Interestingly, the ancient trichostrongylid nematode Strongylus ventricosus from the type host red deer ( Cervus elaphus ) shot near Greifswald (Germany) was described by Rudolphi in 1809. Rudolphi's type material (one male and four females) was deposited in the Museum für Naturkunde (Berlin). Later, the ancient species S. ventricosus was taken as a synonym for various Cooperia spp. Our current re-examination of the type male indicated that there is a relatively good agreement with our new material from Czech deer regarding the most important characteristics of S. ventricosus (i.e., the shape and size of the male spicules); however, Rudolphi's type material is in rather poor condition. The suggested resurrection of the deer Cooperia sp. in this study as Cooperia ventricosa (Rudolphi, 1809) requires verification by collecting and analyzing new nematode material from the type locality near Greifswald., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Albrechtová, Kašparová, Langrová, Hart, Neuhaus, Jankovská, Petrtýl, Magdálek and Špakulová.)

Emerging contaminants and their pervasive presence in freshwater ecosystems have been widely documented, but less is known about their prevalence and the harm they cause in marine ecosystems, particularly in developing countries. This study provides data on the prevalence and risk posed by microplastics, plasticisers, pharmaceuticals and personal care products (PPCPs), and heavy metal(loid)s (HMs) along the Maharashtra coast of India. The sediment and coastal water samples were collected from 17 sampling stations, processed, and subjected to FTIR-ATR, ICP-MS, SEM-EDX, LC-MS/MS, and GC-MS for further analysis. Higher MPs abundance, combined with the pollution load index, indicates that the northern zone is a high-impact zone with pollution concerns. Plasticisers in extracted MPs and HMs adsorption on MPs surface from surrounding waters reveal their roles as a source and vector for contaminants, respectively. The mean concentration of metoprolol (53.7-306 ng L -1 ), tramadol (16.6-198 ng L -1 ), venlafaxine (24.6-234 ng L -1 ), and triclosan (211-433 ng L -1 ) in Maharashtra's coastal waters were several folds higher than in other water systems, raising major health concerns. The hazard quotient (HQ) scores revealed that >70 % of study sites pose a high to medium (1 > HQ > 0.1) ecological risk to fish, crustaceans and algae, indicating serious concern. Fish and crustaceans (35.3 % each) show a higher level of risk than algae (29.5 %). Metoprolol and venlafaxine could represent greater ecological risks than tramadol. Similarly, HQ suggests that bisphenol A has larger ecological risks than bisphenol S along the Maharashtra coast. To the best of our knowledge, this is the first in-depth investigation into emerging pollutants in Indian coastal regions. This information is crucial for better policy formulation and coastal management in India in general, and Maharashtra in particular., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Sustainable plastic-waste management is becoming increasingly challenging as enormous loads of plastic debris regularly accumulate in susceptible ecosystems. The microplastic (MP) particles generated from these plastic wastes are imposing additional threats to these ecosystems due to their small size as well as their ability to adsorb and carry toxic chemicals. The current investigation deals with one such MP-originated toxicant, diethyl phthalate (DEP), and its impact on two species of freshwater loaches from the Western Ghats of India, Lepidocephalichthys thermalis and Indoreonectes evezardi. The MP samples were collected from the sediments of the Mula River and characterized using spectroscopic methods and scanning electron microscopy. Polymers, such as polyvinyl chloride and polypropylene, were identified in the collected MPs. GC-MS analysis of the MP extracts revealed the presence of DEP, confirming the MP waste as a potential source of DEP pollution. Further, to evaluate the effect of DEP on survival of selected loaches, L. thermalis and I. evezardi were exposed to DEP concentrations (18.75-300 mg L -1 ) and the lethal DEP dose (LC 50 ) was estimated to be 44.53 mg L -1 for L. thermalis and 34.64 mg L -1 for I. evezardi. Fishes were further exposed to sub-lethal DEP concentration for one day (Short term exposure: STE) or eight days (Long term exposure: LTE) to analyze the histological condition and oxidative status of the liver in response to DEP treatment. Histology revealed congestion of sinusoids and vacuolization after the LTE. Higher lipid peroxidation levels were also measured in the livers of both species treated with DEP, which indicated DEP-mediated oxidative damage. The antioxidant enzymes including superoxide dismutase, catalase, peroxidase and glutathione-S-transferase displayed elevated activities in response to STE and LTE of DEP. Collectively, the results demonstrate that MPs in the Mula River are a potential source of DEP. The findings also show that DEP exposure can be fatal to freshwater fishes such as loaches, possibly by causing increased oxidative damage to the hepatic system., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Hybridization and polyploidization are important evolutionary processes whose impacts range from the alteration of gene expression and phenotypic variation to the triggering of asexual reproduction. We investigated fishes of the Cobitis taenia-elongatoides hybrid complex, which allowed us to disentangle the direct effects of both processes, due to the co-occurrence of parental species with their diploid and triploid hybrids. Employing morphological, ecological, and RNAseq approaches, we investigated the molecular determinants of hybrid and polyploid forms. In contrast with other studies, hybridization and polyploidy induced relatively very little transgressivity. Instead, Cobitis hybrids appeared intermediate with a clear effect of genomic dosing when triploids expressed higher similarity to the parent contributing two genome sets. This dosage effect was symmetric in the germline (oocyte gene expression), interestingly though, we observed an overall bias toward C. taenia in somatic tissues and traits. At the level of individual genes, expression-level dominance vastly prevailed over additivity or transgressivity. Also, trans-regulation of gene expression was less efficient in diploid hybrids than in triploids, where the expression modulation of homoeologs derived from the "haploid" parent was stronger than those derived from the "diploid" parent. Our findings suggest that the apparent intermediacy of hybrid phenotypes results from the combination of individual genes with dominant expression rather than from simple additivity. The efficiency of cross-talk between trans-regulatory elements further appears dosage dependent. Important effects of polyploidization may thus stem from changes in relative concentrations of trans-regulatory elements and their binding sites between hybridizing genomes. Links between gene regulation and asexuality are discussed., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Roots of terrestrial plants host a wide spectrum of soil fungi that form various parasitic, neutral and mutualistic associations. A similar trend is evident in freshwater aquatic plants and plants inhabiting salt marshes or mangroves. Marine vascular plants (seagrasses), by contrast, seem to lack specific root-fungus symbioses. We examined roots of two Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa, in the northwestern Mediterranean Sea for fungal colonization using light and scanning and transmission electron microscopy. We found that P. oceanica, but not C. nodosa, is regularly associated with melanized septate hyphae in a manner resembling colonization by the ubiquitous dark septate endophytes (DSE) in roots of most terrestrial plants. P. oceanica roots were found to be colonized by sparse dematiaceous running hyphae as well as dense parenchymatous nets/hyphal sheaths on the root surface, intracellular melanized microsclerotia and occasionally also intra- and intercellular hyphae. The colonization was most prominent in the thick-walled hypodermis of the thinnest healthy looking roots, and the mycobiont seemed to colonize both living and dead host cells. Dark septate hyphae infrequently occurred also inside rhizodermal cells, but never colonized vascular tissues. The biological significance of this overlooked marine symbiosis remains unknown, but its morphology, extent, distribution across the NW Mediterranean Sea and absence in C. nodosa indicate an intriguing relationship between the dominant Mediterranean seagrass and its dark septate root mycobionts.

Total mercury concentrations were determined in the gonadal tissues of 15 female and 10 male European perch (Perca fluviatilis) from one location of the stream "Jevanský potok" located about 30 km from Prague (Czech Republic). Tissue samples were frozen at -26 °C in polypropylene containers until further processing, which was carried out using an Advance Mercury Analyser (single purpose atomic absorption spectrometer). Mercury concentrations were present in all analysed gonad samples, and ranged from 2.3 to 12.7 μg/kg wet weight. However, we determined a mean Hg concentration (9.45 μg/kg) in male gonads that was 2.4 times greater than that of female gonads (3.9 μg/kg). This is an important finding when taking into account fish sex in environmental pollution monitoring (especially for mercury contamination).

The headwaters of five large African river basins flow through the Bié Plateau in Angola and still remain faunistically largely unexplored. We investigated fish fauna from the Cuanza and Okavango-Zambezi river systems from central Angola. We reconstructed molecular phylogenies of the most common cichlid species from the region, Tilapia sparrmanii and Serranochromis macrocephalus, using both mitochondrial and nuclear markers. We found evidence for ichthyofaunal contact and gene flow between the Cuanza and Okavango-Zambezi watersheds in the Bié Plateau in central Angola. Waterfalls and rapids also appeared to restrict genetic exchange among populations within the Cuanza basin. Further, we found that the Angolan Serranochromis cichlid fishes represent a monophyletic lineage with respect to other haplochromines, including the serranochromines from the Congo and Zambezi rivers. This study represents an important initial step in a biodiversity survey of this extremely poorly explored region, as well as giving further understanding to species distributions and gene flow both between and within river basins.

We monitored concentrations of Cd, Cu, Mn and Zn in acantocephalan parasites (Acanthocephalus lucii) and its final host (Perca fluviatilis). The concentrations in parasites were found to be significantly higher than those found in the muscle, gonads and liver of fish host. The bioaccumulation factor values (BF=C(parasite)/C(host muscle)) were 194, 24.4, 2.2 and 4.7 for Cd, Cu, Mn and Zn, respectively. This suggests a benefit for the host due to the high accumulation of toxic cadmium., (Copyright © 2011 Elsevier Inc. All rights reserved.)

This study focuses on the comparison of three selected modifications of the McMaster counting technique, namely the McMaster method modified by Wetzel (W) and Zajíček (Z), as well as the concentration McMaster technique according to Roepstorff and Nansen (R&N). These modifications differ in the weights of faeces examined (W, 2 g/Z, 1 g/R&N, 4 g), flotation solutions (W, NaCl/Z, MgSO(4) + Na(2)S(2)O(3)/R&N, NaCl + glucose), centrifugation (W, none/Z, 2,000 RPM for 2 min and 2,000 RPM for 1 min/R&N, 1,200 RPM for 5 min), number of McMaster chambers investigated (W, 3/Z, 2/R&N, 2), and multiplication factors used (W, 67/Z, 33/R&N, 20). To investigate the sensitivity and reliability of these methods, nematode eggs (Teladorsagia circumcincta) were used. Parasite elements are distributed through negative binomial distribution in naturally infected host faeces, and the number of parasite elements in a given amount of faeces sample is unknown to man. Therefore, we decided to prepare the exact number of eggs which were added to the parasite negative faeces; the faecal sample was then investigated. From this perspective, this is the first time a comparison of the McMaster methods has been so accurately investigated. This approach allows us to evaluate the real sensitivity and reliability of the tested method. As the findings of this study indicate, the highest sensitivity and reliability were obtained using the Roepstorff and Nansen modification. This McMaster modification is able to detect 20 eggs per sample (in 70% of samples). Concentrations of 200 and 500 eggs can be found in almost 100% of samples. Moreover, this method is simple, cheap and fast. For these reasons, we can recommend this method for routine veterinary practice.

Lead concentrations in the tissues of perch and its parasites were determined as mg/kg dw. Lead was found at higher concentrations in the acanthocephalans (11.56) than in different tissues (liver, gonads and muscle with skin and bone) of perch. With respect to fish tissues, the highest concentrations of lead were present in the liver (1.24), followed by the gonads (0.57) whereas the lowest concentrations were in the muscle with skin and bone (0.21). The bioconcentration factors for lead indicated that parasites accumulate metals to a higher degree than fish tissues--lead concentrations in acanthocephalans were 9.32, 19.27 and 55.05 higher than in liver, gonads and muscles of host, respectively.

The degeneration of articular cartilage results from osteoarthritis and many other forms of severe arthritis. Current treatments for cartilage repair are less than satisfactory, and rarely restore a full function or return the tissue to its natural state. The leading strategies in the treatment are aimed at the transplantation of cells and/or the use of various biological grafts, bioactive agents, or biologically compatible implant matrices. The insertion of a crushed autologous bone graft has been reported as a possible therapy. However, the regenerative quality of the tissue was less than 70% of healthy cartilage for fragments and controls. The implantation of cycloolefin-blend 3D-cylinders with hydrogel scaffolds on their proximal parts and with the applications of type I collagen films is one of several surgical therapies. The replacement and continuous biomechanical properties of the subchondral bone play an important role in the morphology and the quality of chondrogenesis. The initial biomechanical stability of COC-blend polymer replacements in the subchondral bone contributes to the formation of a new cartilage tissue. The initial bearing capacities of the implanted tissue/replacements and vertical positions of the replacements have a principal influence upon both the quality and the quantity of new articular cartilage.

Two tracer tests were conducted between August 2004 and March 2007 at an ecological farm in western Bohemia. The first tracer test was performed for the summer-autumn grazing period (onset of arrested development), the second for spring (resumption of arrested development). In the first tracer test, the percentage of nematodes arresting development over the winter months reached 87.7% for Teladorsagia circumcincta, 66.7% for Haemonchus contortus, 89.9% for Nematodirus filicollis, 21.6% for Trichostrongylus axei, and 23.9% for both Trichostrongylus vitrinus and Trichostrongylus colubriformis. None of the arrested larvae were observed with species Cooperia curticei, Nematodirus battus, and Oesophagostomum venulosum. In the second tracer test, a significant increase of adult worms was discovered in March of species T. circumcincta and N. filicollis and Trichostrongylus spp. in February. Redundancy analysis and generalized linear models analyses have confirmed that environmental conditions play a crucial role in hypobiosis of sheep strongyles in the Czech Republic. The analysis of influences of various environmental factors revealed that the number of arrested larvae was negatively influenced by light-day length, sunshine, or daylight decrease (p < 0.01).

We studied the biocompatibility of the carbon composites and polyethylene materials with and without collagen or collagen and proteoglycan cover. We used the in vitro technology to study the adhesion of model cells evalution, their metabolic activity and the production of TNF-alpha as a cytokine model. Under in vivo condition, the biocompatibility of tested polymers were studied in the implantation experiment, subcutaneously in the interscapular region in the laboratory rat. We have found in the in vitro assay favorable proliferation and the smallest production of pro-inflammatory TNF-alpha cytokine in cells adherent to the hydrophobic polyethylene material coated with biological macromolecules. Using in vivo tests performed by the implantation of materials to the rat we demonstrated that the materials are not cytotoxic. The tissue capsule surrounding the implants was not significantly influenced by the type of the implant and the pre-treatment by the biological molecules. However, the foreign-body giant multinucleated cells were observed only in the vicinity of the collagen - covered hydrophobic polyethylene implant. Interestingly, while the collagen coating improved the biocompatibility of tested polymers in vitro, the inflammatory reaction against this covered materials was higher under in vivo conditions. The pre-treatment of carbon composites by both types of biological macromolecules reduced the occurrence of carbon debris in the implantation site. The tested carbon composites and polyethylene materials are not toxic. The pre-treatment of the materials by extracellular matrix components increased their biological tolerance in vitro and reduced implant wears in animal experiment, which can be important for the medical application.

Purpose of the Study: Connective tissue components, particularly collagen and proteoglycan, stimulate cell proliferation and thus promote tissue regeneration. This fact was utilized to test some new implant materials, which were covered by these components, for the speed and quality of their encapsulation., Material: The materials tested included polyethylene (PE) with either a hydrophobic (HPHO) or a hydrophilic (HPHI) surface and the C-C composite. Before implantation in experimental animals, the materials were coated with a thin layer of collagen-proteoglycan copolymer., Methods: Collagen was obtained from calf hide (ISC 40 fraction) and proteoglycan was isolated from calf cartilage with 2M GuHCl. The concentrations of elements in implant materials were assessed by the method of ESCA photoelectron spectroscopy (electron spectroscopy for chemical analysis) and, using a comparison of the values of electron binding energies at inner levels with the published ones, the chemical states of elements were identified., Results: Carbon, oxygen and silicon were identified on the surface of the PE HPHI sample; carbon, oxygen, calcium, manganese and sulfur were found on the PE HPHO sample and nitrogen, oxygen and fluorine were present on the C-C composite., Discussion: In our group of patients there was a small rate of rheumatoid arthritis, while in most literature these patients are predominant. In accordance with the outcomes of other authors, ASS is fraught with recurrence. ASS does not strike to fibrous capsule, like an open surgery synovectomy, and from these islands synovialis could regenerate., Conclusions: The presence of manganese and calcium on the surfaces of the materials investigated indicates the existence of a collagen-proteoglycan copolymer, which contains NH2 and COO groups derived from collagen and SO4 groups from proteoglycan. It is necessary to verify this theoretical assumption based on measurement data in a biological experiment.

A secondarilly remodelled bone (the haversian bone) forming a wall of human shaft represents a significantly anisotropic material, which has different strengths in different directions. One of the factors influencing mechanical properties (strength in particular) of the bone is the architectonics of the compact bone. Osteons of the haversian bone are arranged in the direction of the dominant first principal stress and create two antirotational spiral systems in the opposite walls of the shaft. The aim of the work was to found out how the bone tensile strength depends on the orientation of osteons and check whether the premise applies that the architectonics of the haversian bone depends on the directions of the first principal stress and in what relation of strength moments the direction of the first principal stress corresponds to the actual orientation of osteons. The results of the tensile strength tests in wet samples from 10 femurs and the strength of the whole shaft in 9 pairs of femurs (cadaver material) have confirmed the premise that osteons are arranged in the directions of the dominant first principal stress and depend on the relation between bending and torsion moments. The strength of the femoral shaft is maximal in the physiological way of loading, i.e. in medial bending and outer rotation. The decisive motion on which the strength of the bone depends is torsion. In non-physiological loading the femoral shaft (by an opposite bending moment or opposite torsion moment in medial bending) the strength of the bone is significantly lower. From the biomechanical viewpoint the architecture of the haversian bone has an optimal and efficient structure. Key words: compact bone, bone strength, types of loading.

The authors elaborated a new macroscopic method which made it possible to analyze the orientation of osteons in the entire diaphysis. All long bones of the human extremities were thus analyzed. In each bone the osteons are arranged in a specific pattern but according to a uniform plan. Most of them are oriented in an oblique direction and are arranged as two helices of opposite directions located on opposite sides of the bone. The two fields are separated by a sharp borderline. Biomechanical analysis revealed that the orientation of the osteons is consistent with the direction of the maximal principal stress which depends on the normal and torsional stress to which the bone is exposed. From the orientation of osteons the authors derived ex post the mode of dominant loading of all long bones: the femur is exposed to bending in the medial direction and to outer rotation, the tibia is exposed to bending in dorsal direction and to inner rotation. The humerus is bent in the medial direction, the radius in the dorsal one. Both these bones are exposed to loading in inner rotation. In the ulna and fibula the mode of stress could not be assessed by the authors' method. The results are summarized in two diagrams which indicate the orientation of osteons and the way in which the long bones in man are exposed to load. The authors discuss the theoretical and practical impact of these findings.