Biotic homogenization of Central European urban floras depends on residence time of alien species and habitat types

Spread of alien species may result in biotic homogenization, i.e. increasing similarity between biotas of different areas. We examined whether the flora of Central European cities is becoming homogenized because of the spread of alien species, whether the contribution of aliens to homogenization depends on residence time, and whether habitats under more intense human pressure are more homogenized. Using floristic composition data from a standardized sample of 1-ha plots located in seven habitat types in 32 cities in Central Europe, Belgium and the Netherlands, we compared homogenization effects of archaeophytes (pre-AD 1500 aliens) and neophytes (post-AD 1500 aliens) using rarefaction curves, Jaccard dissimilarity index, Mantel tests and homogenization index. We found that archaeophytes contributed to homogenization and neophytes to differentiation of floras among cities, but generally the spread of alien species caused differentiation. Differentiation was low in the most disturbed urban habitats, such as city squares, boulevards or early successional sites, but was strongest in moderately disturbed habitats, such as city parks and residential areas with an open building pattern. We conclude that biotic homogenization depends on alien plants’ residence time. Aliens introduced within the past five centuries are often rare, not yet having achieved their potential range; they therefore increase floristic differentiation. Conversely, species introduced more than five centuries ago have had sufficient time to disperse into most suitable habitats, and consequently contribute to homogenization. Although invasions may therefore initially increase biodiversity, they could ultimately lead to homogenization. These processes are faster and stronger in more disturbed habitats.     

First report of dry rot of potato caused by Fusarium proliferatum in India

Journal of Plant Diseases and Protection - Potato stands first as a non-cereal food crop for global consumption purposes. During the year 2019–20, dry rot disease symptoms were observed on...     

Effect of Acid Aluminous Soil on Photosynthetic Parameters of Potato (Solanum tuberosum L.)

Potato is grown worldwide, in some cases in very acid soils. Aluminum (Al) is a major limiting factor for crop productivity in acid soils. Al toxicity was studied mainly on plant roots, while less attention was given to its effects on leaves. Al tolerance observed in solution cultures has rarely been correlated with Al tolerance in acid soils. Al tolerance was assessed in 12 potato cultivars grown in nutrient solutions containing 0, 25, and 50 μmol Al L^?1 by its relative root elongation (RRE). The effect of acid soil with high level of exchangeable Al on leaf mineral content, chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO₂ concentration, water use efficiency (WUE), and light use efficiency (LUE) was studied on cultivars, with the greatest differences in RRE (cv. Tresor, 63.1 and 42.5% and cv. Canberra, 23.3 and 19.2%, for the 25 and 50 μmol Al L^?1 treatments, respectively), grown for 49 days after planting (DAP) in acid and limed soil. Growth in acid soil significantly reduced concentrations of nitrogen (?18.51%) and magnesium (?27.17%) in the leaves in cv. Canberra and concentrations of potassium and copper in both cultivars. Canberra grown in acid soil showed a significant decrease in chlorophyll content and photosynthetic rate, from 28 to 49 DAP, and in transpiration rate and LUE when averaged across all measurements, while cv. Tresor was not affected. Physiological disorders observed on leaves of plants grown in acid soil can be correlated with the differences in Al tolerance observed in nutrient solutions.     

Heavy Metal Content of Soils and Plum Orchards in an Uncontaminated Area

There are multiple stressors derived from urbanizations that result in frequent disturbances on streams and rivers reducing water quality and threatens aquatic biota. P-glycoprotein (P-gp)-mediated multixenobiotic resistance (MXR) is a defence mechanism analogous to multidrug resistance (MDR), which has been demonstrated in several aquatic organisms. This system protects cells against the entry and the accumulation of xenobiotics and has been proposed as a biomarker for pollution assessment. We conducted a study in a post-urban reach of Esquel stream (Chubut Province) downstream a wastewater treatment plant, in order to assess the presence and activity of MXR in five freshwater macroinvertebrate species (Helobdella michaelseni, Helobdella simplex, Patagoniobdella variabilis, Hyalella curvispina and Chironomus riparius). We measured the accumulation of the model P-gp substrate rhodamine B (RB) in organisms previously exposed to pollution. Our results described the activity of the MXR system in the three species of leeches suggesting their suitability as the in vivo biomonitoring. We also identified a dependence of the transporter activity with the development stage in H. simplex, highlighting the importance of using organisms of similar size classes since it may affect observed results. Finally, we concluded that benthic freshwater macroinvertebrates possess different species-specific levels of MXR activity possibly influencing their natural distribution as well as their survival.     

Magnetic superstructure in the two-dimensional quantum antiferromagnet SrCu2(BO3)2

We report the observation of magnetic superstructure in a magnetization plateau state of SrCu2(BO3)2, a frustrated quasi-two-dimensional quantum spin system. The Cu and B nuclear magnetic resonance (NMR) spectra at 35 millikelvin indicate an apparently discontinuous phase transition from uniform magnetization to a modulated superstructure near 27 tesla, above which a magnetization plateau at 1/8 of the full saturation has been observed. Comparison of the Cu NMR spectrum and the theoretical analysis of a Heisenberg spin model demonstrates the crystallization of itinerant triplets in the plateau phase within a large rhomboid unit cell (16 spins per layer) showing oscillations of the spin polarization. Thus, we are now in possession of an interesting model system to study a localization transition of strongly interacting quantum particles.     

Phage displayed peptides and anti-idiotype antibodies recognised by a monoclonal antibody directed against a diagnostic antigen of Mycoplasma capricolum subsp. capripneumoniae

A monoclonal antibody (Mab 4.52) raised against Mycoplasma capricolum subsp. capripneumoniae (Mccp) cell lysate was used as a template to obtain substitute antigens recognised by its paratope. Two approaches were investigated: a 17-mer random peptide library displayed on the surface of a filamentous phage was screened by panning on the immobilised Mab 4.52 and anti-idiotype antibodies were generated by immunising a chicken with the F(ab')(2) fragments of the antibody. Analysis of the peptide sequences displayed by the isolated phages identified two peptides. Both contained two cysteine residues and had identical or similar amino acids in positions 5 (P), 8 (I/L) and 13 (L). The fusion phages were also recognised by Mab 4.52 in enzyme-linked immunosorbent assay (ELISA) and binding was shown by surface plasmon resonance. One of the peptides was a markedly better inhibitor (67%) of the binding of Mab 4.52 to its original antigen than the other (20%) at 1mg/ml. After absorption, to remove isotypic and allotypic reactivities, the anti-idiotype IgY was specifically recognised by Mab 4.52 in ELISA and was able to inhibit its binding to the original antigen, whereas anti-idiotype antibodies raised against a bluetongue virus-specific antibody had no effect. In spite of unequivocal binding of the anti-idiotype antibodies and the fusion phages to the paratope of Mab 4.52, goat antisera appeared not to react with either of the surrogate antigens. In contrast, the test sera bound to the original antigen suggesting that Mab 4.52 does not recognise exactly the same antigenic site as antibodies in the goat antisera.     

Trichinella pseudospiralis in pig from Croatia

Trichinella spiralis and Trichinella britovi are species that are frequently found in domestic pigs and various sylvatic animals in Croatia. During routine trichinoscopy, non-encapsulated larvae were detected in the muscle tissue of a domestic pig. Artificial digestion revealed a larvae burden of 602 muscle larvae per gram of tissue. Tissue section analysis confirmed the presence of non-encapsulated larvae. Multiplex PCR identified the larvae as T. pseudospiralis. This observation is consistent with the reports of a local veterinary inspector who described the presence of non-encapsulated Trichinella in four individual cases over the last 2 years. This is the first report of T. pseudospiralis in Croatia and one of very few cases of T. pseudospiralis infection described in domestic pigs. The detection of non-encapsulated larvae stresses the need for implementation of artificial digestion instead of trichinoscopy for the detection and identification of Trichinella infections.     

Antioxidant,Antimicrobial and Genotoxicity Screening of Hydro-alcoholic Extracts of Five Serbian <Emphasis Type="Italic">Equisetum</Emphasis> Species

The hydro-alcoholic extracts of five Equisetum species, E. arvense L., E. sylvaticum L., E. fluviatile L., E. palustre L. and E. telmateia Ehrh., growing-wild in Serbia were evaluated for their genotoxicity, antimicrobial activity, antioxidant capacity and the results related to the total phenol content and HPLC flavonoid profiles. The total phenol content was 92–349 μmol expressed as equivalents of chlorogenic acid per g of dried plant material. Main identified compounds were kaempferol-, quercetin- glycosides and caffeic acid derivatives. E. telmateia extract showed the greatest antioxidant capacity. Almost all tested microorganisms demonstrated some degree of sensitivity to the examined extracts. All tested extracts at 62.5 μg/ml showed higher incidence of micronucleus formation than in the control sample. The obtained data allowed mutual comparison of examined species and their assessment as possible sources of antioxidants, antimicrobials and/or genotoxic substances.     

Effects of fish farming on microbial planktonic communities in the middle Adriatic sea

The effects of farming on planktonic microbial communities were investigated at the coastal sea bass/sea bream farm in the oligotrophic middle Adriatic Sea. Analyses of nutrients, chlorophyll a, cyanobacteria (Prochlorococcus), heterotrophic bacteria and nanoflagellates (both pigmented and heterotrophic) were carried out on samples taken during six seasonal cruises at different water depths. Farming activity increased the natural concentrations of some nutrients (ammonium, nitrite, phosphate, dissolved inorganic nitrogen) and changed their seasonal pattern. The values still remained typical for oligotrophic environ‐ments demonstrating no risk for eutrophication. Enhanced nutrient supply provoked an immediate increase in abundances of both autotrophic and heterotrophic microbial groups (except pigmented nanoflagellates) and chlorophyll a. The effect of farming was more visible for the heterotrophic microbial component. Results from this study reveal a potential common pattern of microbial response to farming in the oligotrophic environments. It also suggests the importance of heterotrophic microbial web in transferring the matter and energy released from the fish farms in nutrient poor environments.