Effects of alkylating agents on lymphocytes from controls and from patients with Fanconi's anemia

Summary The frequency of sister chromatid exchanges (SCE) and chromosome aberrations and the dynamics of cell division in peripheral blood lymphocytes of four patients with Fanconi's anemia were studied after in vitro exposure to alkylating agents TEPA and mitomycin.SCE frequency was significantly increased even after very low doses of mutagens, while chromosome aberrations were significantly increased only after high doses (0.160 g/ml mitomycin and 10^-5 M TEPA). The responses of Fanconi's anemia cells and control cells did not differ significantly. The increased frequency of both SCE and chromosome aberrations was accompanied by gradual delay of cell division, which was most conspicuous in cells from patients with Fanconi's anemia.     

Thermal stabilisation of the short DNA duplexes by acridine-4-carboxamide derivatives

The short oligodeoxynucleotide (ODN) probes are suitable for good discrimination of point mutations. However, the probes suffer from low melting temperatures. In this work, the strategy of using acridine-4-carboxamide intercalators to improve thermal stabilisation is investigated. The study of large series of acridines revealed that optimal stabilisation is achieved upon decoration of acridine by secondary carboxamide carrying sterically not demanding basic function bound through a two-carbon linker. Two highly active intercalators were attached to short probes (13 or 18 bases; designed as a part of HFE gene) by click chemistry into positions 7 and/or 13 and proved to increase the melting temperate (T_m) of the duplex by almost 8°C for the best combination. The acridines interact with both single- and double-stranded DNAs with substantially preferred interaction for the latter. The study of interaction suggested higher affinity of the acridines toward the GC- than AT-rich sequences. Good discrimination of two point mutations was shown in practical application with HFE gene (wild type, H63D C > G and S65C A > C mutations). Acridine itself can also serve as a fluorophore and also allows discrimination of the fully matched sequences from those with point mutations in probes labelled only with acridine.     

Purification and characterization of a nitrilase from Fusarium solani O1

An intracellular nitrilase was purified from a Fusarium solani O1 culture, in which the enzyme (up to 3000 U L⁻¹) was induced by 2-cyanopyridine. SDS-PAGE revealed one major band corresponding to a molecular weight of approximately 40 kDa. Peptide mass fingerprinting suggested a high similarity of the protein with the putative nitrilase from Gibberella moniliformis. Electron microscopy revealed that the enzyme molecules associated into extended rods. The enzyme showed high specific activities towards benzonitrile (156 U mg⁻¹) and 4-cyanopyridine (203 U mg⁻¹). Other aromatic nitriles (3-chlorobenzonitrile, 3-hydroxybenzonitrile) also served as good substrates for the enzyme. The rates of hydrolysis of aliphatic nitriles (methacrylonitrile, propionitrile, butyronitrile, valeronitrile) were 14–26% of that of benzonitrile. The nitrilase was active within pH 5–10 and at up to 50 °C with optima at pH 8.0 and 40–45 °C. Its activity was strongly inhibited by Hg²⁺ and Ag⁺ ions. More than half of the enzyme activity was preserved at up to 50% of n-hexane or n-heptane or at up to 15% of xylene or ethanol. Operational stability of the enzyme was examined by the conversion of 45 mM 4-cyanopyridine in a continuous and stirred ultrafiltration-membrane reactor. The nitrilase half-life was 277 and 10.5 h at 35 and 45 °C, respectively.     

Macroinvertebrates of flooded trees in the man-made Volta Lake (Ghana) with special reference to the burrowing Mayfly Povilla adusta Navas

Summary The species composition of periphytic macroinvertebrates on and in flooded trees differs at different localities on the Volta Lake. The main differences concern chironomid and trichopteran larvae. The reasons for this lie in the different exposure of trees to wave action, in the availability of soft wood and bark as a substrate, and in the distance of trees off-shore. All these factors determine the intensity of growth of the periphytic algae. The growth of the periphytic fauna will also be influenced by the density of phytoplankton on which it feeds. Other factors, such as oxygen concentration and the turbidity of the water, are also likely to affect the productivity of the whole community.The abundance of Povilla nymphs, the most common organism in trees, seems to depend on the type of the substrate. The bark of trees is exploited more than the wood, and trees with harder wood are less attacked than those with soft wood. Macroscopically, the male nymphs can be distinguished from female nymphs from a length of 6.0 mm, and they start to emerge when 9.0 mm long. Females emerge from 14.0 mm length. Nymphs tend to be heavier in dense populations. The difference in the weight of nymphs may be due to differences in availability of food.Nymphs of Povilla were found to feed both on solitary and attached periphytic algae, together with detritus and planktonic algae. Because of the great abundance of Povilla the nymphs of this species are of great importance in the conversion of algae into animal protein, being themselves heavily exploited by fish.No lunar periodicity, such as occurs on Lake Victoria, was found, and Povilla in the Volta Lake seems to emerge continuously.     

An outbreak of philophthalmosis in Larus michahellis and Larus fuscus gulls in Iberian Peninsula

Trematodes of the genus Philophthalmus Loos, 1899 are the eye parasites of birds and mammals, which use freshwater snails as their first intermediate hosts. Here we examined the presence of philophthalmids in a total of 1515 gulls (589 Larus fuscus and 926 Larus michahellis) admitted between January 2010 and October 2016 for rehabilitation at Olhão (Portugal), by the use of combined morphological and molecular analysis. We recorded the first infected L. fuscus and L. michahellis in July and November 2015, respectively. The philophthalmids were located in the conjunctival sac or under the nictitating membrane. Gulls infected with Philophthalmus lucipetus Rudolphi, 1819 presented no clinical signs, while those infected with Philophthalmus lacrymosus Braun, 1902 presented serious eye damage in the same host species. The prevalence of P. lucipetus reached 3.6% in L. fuscus and 0.8% in L. michahellis; the prevalence of P. lacrymosus reached 0.3% and 0.0%, respectively. The outbreak of P. lucipetus likely started in a narrowly defined area, since the first six cases, found between July and October 2015, originated from a single municipality, and only later more cases started to be retrieved from other municipalities of Portugal. These findings represent the first records of both philophthalmids in the Iberian Peninsula, their first records in L. michahellis and the first record of P. lacrymosus in L. fuscus. Further follow-up of the outbreak and the identification of intermediate hosts are needed.     

Multiple stressors on biotic interactions: how climate change and alien species interact to affect pollination

Global change may substantially affect biodiversity and ecosystem functioning but little is known about its effects on essential biotic interactions. Since different environmental drivers rarely act in isolation it is important to consider interactive effects. Here, we focus on how two key drivers of anthropogenic environmental change, climate change and the introduction of alien species, affect plant–pollinator interactions. Based on a literature survey we identify climatically sensitive aspects of species interactions, assess potential effects of climate change on these mechanisms, and derive hypotheses that may form the basis of future research. We find that both climate change and alien species will ultimately lead to the creation of novel communities. In these communities certain interactions may no longer occur while there will also be potential for the emergence of new relationships. Alien species can both partly compensate for the often negative effects of climate change but also amplify them in some cases. Since potential positive effects are often restricted to generalist interactions among species, climate change and alien species in combination can result in significant threats to more specialist interactions involving native species.     

Primary structure of apolipophorin-III from the greater wax moth,Galleria mellonella

The complete amino acid sequence of apolipophorin-III (apoLp-III), a lipid-binding hemolymph protein from the greater wax moth,Galleria mellonella, was determined by protein sequencing. The mature protein consists of 163 amino acid residues forming a protein of 18,075.5 Da. Its sequence is similar to apoLp-III from other Lepidopteran species, but remarkably different from the apoLp-IIIs of insects from other orders. As shown by mass spectrometric analysis, the protein carries no modifications. Thus, all of its known physiological functions, including its recently discovered immune response-stimulating activity, must reside in the protein itself.