New records and descriptions of digeneans from the Magellanic penguin Spheniscus magellanicus (Forster) (Aves: Sphenisciformes) on the coast of Brazil

Five species of digeneans parasitic in the Magellanic penguin Spheniscus magellanicus (Forster) from off the Brazilian coast of the western Atlantic are reported for the first time from this host and described. These are Mesostephanus odhneri (Travassos, 1924) Lutz, 1935, Posthodiplostomum macrocotyle Dubois, 1937, Stephanoprora uruguayensis Holcman-Spector & Olagüe, 1989, Ascocotyle (Phagicola) longa Ransom, 1920 and Ascocotyle (Phagicola) sp. One other digenean, Cardiocephaloides physalis (Lutz, 1926) Sudarikov, 1959, was also recorded. The taxonomy of the species and available data on their life-cycles are commented upon in relation to the possible origins of digenean infections of the Magellanic penguin.     

Physiological diversity of bacterial communities from different soil locations on Livingston Island, South Shetland archipelago, Antarctica

Terrestrial food webs of Antarctica are simple and dominated by microorganisms. Soil bacteria play an important role in nutrient cycling, yet little is known about their capacity to utilize different carbon sources and to participate in site nutrient turnover. Biolog EcoPlate? was applied to study the catabolic activity and physiological diversity of bacteria inhabiting the soil of moss, vascular plants, and fell field habitats from Livingston Island, Antarctica. Additionally, the number of oligotrophic and copiotrophic bacteria was counted by the agar plate method. Results indicated a lack of site-specific distribution of bacterial abundance, in contrast to bacterial catabolic activity and community level physiological profiles. Community level physiological profiles revealed a common capacity of soil bacteria to intensively utilize polyols, which are cryoprotectants widely produced by Antarctic organisms, as well as site-specific phenolic compounds (vegetated habitats), amino acids/amines (moss habitats), carbohydrates and carboxylic acids (fell field habitat). It was concluded that the physiology of soil bacteria is habitat specific concerning both the rate of catabolic activity and pattern of carbon source utilization.     

Rapid colonisation of Lymnaea stagnalis by larval trematodes in eutrophic ponds in central Europe

High recruitment rates of multiple species and hierarchical competition are the keys to a competitive exclusion model of community assembly in larval trematode communities in molluscs. Eutrophic environments provide conditions for accelerating trematode transmission and this would increase the strength of interspecific interactions. To test these predictions, we provide the first known assessment for a pulmonate snail host, and for highly productive aquatic environments, of the rates of colonisation and extinction at the level of individual snail host patches, of a large guild of trematode species. Using a uniquely large dataset from a relatively long-term mark-recapture study of Lymnaea stagnalis in six eutrophic fishponds in central Europe, we demonstrate extraordinarily rapid colonisation by trematodes of a snail host, thus meeting the assumptions of the competitive exclusion model. Overall annual colonisation rates ranged from 243% to 503% year⁻¹ so that the odds of trematode establishment in an individual snail in these ponds are two to five times per year. Extinction rates were substantially lower than colonisation rates and, therefore, would not result in turnover rates high enough to significantly affect prevalence patterns in the snail populations. At the species level, analyses of sample-based estimates of probabilities of colonisation revealed that shared species traits associated with transmission and competitive abilities determined the limits of colonisation abilities. Colonisation rates were exceedingly high for the species transmitted to the snails passively via eggs. There was a significant effect of species competitive abilities on colonisation rates due to subordinate species being substantially better colonisers than both strong and weak dominants, a pattern consistent with the predictions of the competition-colonisation trade-off hypothesis. Our results suggest that, with the extraordinarily high trematode colonisation potential in the area studied, the spatial and temporal patterns of intraspecific heterogeneity in recruitment may provide conditions for intensification of interspecific interactions so that complex community assembly rules may be involved.     

A new cryptic species of <Emphasis Type="Italic">Aponurus</Emphasis> Looss, 1907 (Digenea: Lecithasteridae) from Mediterranean goatfish (Teleostei: Mullidae)

The status of the trematode Aponurus laguncula Looss, 1907 in the western Mediterranean is re-assessed by means of a comparative morphological study and rDNA sequences based on newly collected material. A. laguncula (sensu stricto) is redescribed from Trachinus draco L. and a new cryptic species of the ‘A. laguncula complex’, Aponurus mulli n. sp., is described on the basis of abundant material from Mullus barbatus L. (type-host) and M. surmuletus L. off the Spanish Mediterranean coasts. The new species is differentiated from A. laguncula (sensu stricto) by its: significantly larger, elongate body, with maximum width at the level of the ventral sucker; shorter forebody; distinctly larger sinus-sac, seminal receptacle and seminal vesicle, with the latter also being more elongate; vesicular pars prostatica; more anteriorly located vitellarium, which consists of eight globular follicles; and distinctly smaller eggs, which are also smaller in relation to body size and have both their opercular and anopercular poles rounded. The variability and the allometric growth of the morphological characters in the new species were studied in detail, resulting in additional distinguishing features. Sequences of the large subunit rRNA (28S) gene (domains D1–D3) and ITS2 rRNA gene region for the new species have been submitted to GenBank in order to enhance future studies on species differentiation within the ‘A. laguncula complex’.     

Distribution of a novel enzyme of sialidase family among native filamentous fungi

Sialidases (neuraminidases, EC 3.2.1.18) are widely distributed in biological systems but there are only scarce data on its production by filamentous fungi. The aim of this study was to obtain information about sialidase distribution in filamentous fungi from non-clinical isolates, to determine availability of sialidase gene, and to select a perspective producer. A total of 113 fungal strains belonging to Ascomycota and Zygomycota compassing 21 genera and 51 species were screened. Among them, 77 strains (11 orders, 14 families and 16 genera) were able to synthesize sialidase. Present data showed a habitat-dependent variation of sialidase activity between species and within species, depending on location. Sialidase gene was identified in sialidase-positive and sialidase-negative strains. .Among three perspective strains, the best producer was chosen based on their sialidase production depending on type of cultivation, medium composition, and growth temperature. The selected P. griseofulvum Р29 was cultivated in 3L bioreactor at 20 °C on medium supplemented with 0.5% milk whey. The results demonstrated better growth and 2.3-fold higher maximum enzyme activity compared to the shaken flask cultures. Moreover, the early occurring maximum (48 h) is an important prerequisite for future up scaling of the process.     

The Rho-guanine nucleotide exchange factor Trio controls leukocyte transendothelial migration by promoting docking structure formation

Leukocyte transendothelial migration involves the active participation of the endothelium through the formation of apical membrane protrusions that embrace adherent leukocytes, termed docking structures. Using live-cell imaging, we find that prior to transmigration, endothelial docking structures form around 80% of all neutrophils. Previously we showed that endothelial RhoG and SGEF control leukocyte transmigration. In this study, our data reveal that both full-length Trio and the first DH-PH (TrioD1) domain of Trio, which can activate Rac1 and RhoG, interact with ICAM-1 and are recruited to leukocyte adhesion sites. Moreover, upon clustering of ICAM-1, the Rho-guanine nucleotide exchange factor Trio activates Rac1, prior to activating RhoG, in a filamin-dependent manner. We further show that docking structure formation is initiated by ICAM-1 clustering into ring-like structures, which is followed by apical membrane protrusion. Interestingly, we find that Rac1 is required for ICAM-1 clustering, whereas RhoG controls membrane protrusion formation. Finally, silencing endothelial Trio expression or reducing TrioD1 activity without affecting SGEF impairs both docking structure formation and leukocyte transmigration. We conclude that Trio promotes leukocyte transendothelial migration by inducing endothelial docking structure formation in a filamin-dependent manner through the activation of Rac1 and RhoG.     

Synthesis,in vitro biological activity,hydrolytic stability and docking of new analogs of BIM-23052 containing halogenated amino acids

One of the potent somatostatin analogs, BIM-23052 (DC-23-99) d-Phe-Phe-Phe-d-Trp-Lys-Thr-Phe-Thr-NH₂, has established in vitro growth hormone inhibitory activity in nM concentrations. It is also characterized by high affinity to some somatostatin receptors which are largely distributed in the cell membranes of many tumor cells. Herein, we report the synthesis of a series of analogs of BIM-23052 containing halogenated Phe residues using standard solid-phase peptide method Fmoc/OtBu-strategy. The cytotoxic effects of the compounds were tested in vitro against two human tumor cell lines—breast cancer cell line and hepatocellular cancer cell line, as well as on human non-tumorigenic epithelial cell line. Analogs containing fluoro-phenylalanines are cytotoxic in μM range, as the analog containing Phe (2-F) showed better selectivity against human hepatocellular cancer cell line. The presented study also reveals that accumulation of halogenated Phe residues does not increase the cytotoxicity according to tested cell lines. The calculated selective index reveals different mechanisms of antitumor activity of the parent compound BIM-23052 and target halogenated analogs for examined breast tumor cell lines. All peptides tested have high antitumor activity against the HepG2 cell line (IC₅₀ ≈ 100 μM and SI > 5) compared to breast cells. This is probably due to the high permeability of the cell membrane and the higher metabolic activity of hepatocytes. In silico docking studies confirmed that all obtained analogs bind well with the somatostatin receptors with preference to ssrt3 and ssrt5. All target compounds showed high hydrolytic stability at acid and neutral pH, which mimic physiological condition in stomach and human plasma.