Effect of invader removal: pollinators stay but some native plants miss their new friend

Removal of invasive species often benefits biological diversity allowing ecosystems’ recovery. However, it is important to assess the functional roles that invaders may have established in their new areas to avoid unexpected results from species elimination. Invasive animal-pollinated plants may affect the plant–pollination interactions by changing pollinator availability and/or behaviour in the community. Thus, removal of an invasive plant may have important effects on pollinator community that may then be reflected positive or negatively on the reproductive success of native plants. The objective of this study was to assess the effect of removing Oxalis pes-caprae, an invasive weed widely spread in the Mediterranean basin, on plant–pollinator interactions and on the reproductive success of co-flowering native plants. For this, a disturbed area in central Portugal, where this species is highly abundant, was selected. Visitation rates, natural pollen loads, pollen tube growth and natural fruit set of native plants were compared in the presence of O. pes-caprae and after manual removal of their flowers. Our results showed a highly resilient pollination network but also revealed some facilitative effects of O. pes-caprae on the reproductive success of co-flowering native plants. Reproductive success of the native plants seems to depend not only on the number and diversity of floral visitors, but also on their efficiency as pollinators. The information provided on the effects of invasive species on the sexual reproductive success of natives is essential for adequate management of invaded areas.     

Influence of surface copper content on Stenotrophomonas maltophilia biofilm control using chlorine and mechanical stress

Abstract

This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10?mg l^?1 of free chlorine for 10?min, an increased shear stress (a fluid velocity of 1.5?m s^?1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.     

Characterization and expression analysis of P5CS (Δ1-pyrroline-5-carboxylate synthase) gene in two distinct populations of the Atlantic Forest native species Eugenia uniflora L.

Molecular Biology Reports - Eugenia uniflora is an Atlantic Forest native species, occurring in contrasting edaphoclimatic environments. The identification of genes involved in response to abiotic...     

Landscape context determinants to plant diversity in the permanent meadows of Southern European Alps

In the Southern Alps, the role of landscape context on meadows plant diversity was evaluated using a multi-model information theoretic approach and five competing hypotheses of landscape context factors: habitat quality (H1), matrix quality (H2), habitat change (H3), matrix quality change (H4) and topography-environmental conditions (H5)- measured at three spatial scales (125, 250 and 500 m). Shannon diversity index and species richness represented plant diversity obtained in 34 plots (100 m² size). Landscape context affected plant diversity measures differently. Matrix quality change at larger scale (500 m) was the most supported hypothesis explaining Shannon diversity index, while species richness responded mostly to topography-environmental conditions in the immediate surroundings (125 m). No effects of present-day habitat and matrix quality (H1 and H2) were found. Matrix quality change affected positively Shannon diversity index through an effect of landscape neighbourhood context on farming management practices. Due to the importance of exposure and inclination of slopes, topography-environmental conditions influenced species richness mostly through energy-driven processes and farming management strategies. In terms of scale, matrix quality change was the strongest hypothesis explaining Shannon diversity index at all scales, while the underlying process affecting species richness changed with scale (H5 or H3). Overall, landscape context explained only 25–28 % of the variation in plant diversity, suggesting that landscape management may support biodiversity conservation when comprised in a global strategy including farming practices. In the study area, change in landscape diversity may be a good indicator for Shannon diversity index and south-eastern facing meadows should be preserved.     

Structure of an early native‐like intermediate of β2‐microglobulin amyloidogenesis

To investigate early intermediates of β2‐microglobulin (β2m) amyloidogenesis, we solved the structure of β2m containing the amyloidogenic Pro32Gly mutation by X‐ray crystallography. One nanobody (Nb24) that efficiently blocks fibril elongation was used as a chaperone to co‐crystallize the Pro32Gly β2m monomer under physiological conditions. The complex of P32G β2m with Nb24 reveals a trans peptide bond at position 32 of this amyloidogenic variant, whereas Pro32 adopts the cis conformation in the wild‐type monomer, indicating that the cis to trans isomerization at Pro32 plays a critical role in the early onset of β2m amyloid formation.     

Larval and juvenile development of dusky grouper Epinephelus marginatus reared in mesocosms

The larval development of the dusky grouper Epinephelus marginatus up to the benthic juvenile stage is described in detail to establish a reference for their larval identification. Development is described in terms of ontogenetic changes in morphology, growth, pigmentation, fin structure and skeletal structure. Larvae were reared in mesocosms at a mean temperature of 24·3° C, salinity of 36·5, dissolved oxygen of 6·4 mg l^?1 and pH of 8·2. Newly hatched larvae had an estimated total length (L_T) of 2·3 mm. On the second day post hatching the yolk was almost fully absorbed with traces of the oil globule still present, the eyes were already pigmented and mouth and gut functional. At this stage the cranial skeletal elements for feeding and breathing (mouth and gills) and the pectoral‐fin support were already present. About 50% of the observed larvae had food in their guts. Pigmentation was very characteristic, consisting of two large chromatophores visible on the edge of the primordial fin, close to the midpoint of the post‐anal region of the body and over the midgut and hindgut and post‐anal portion of the body. At 2·9 mm L_T the emergence of the second dorsal‐fin spine, characteristic of the Epinephilinae, was clearly visible. The pre‐flexion stage started in larva of 3·2 mm L_T. At 5·5 mm L_T the larvae possessed posterior preopercular angle spines, and the dorsal and pelvic spines presented serrated edges and were pigmented. The water surface‐tension‐related death of the yolk sac and pre‐flexion larvae described in the rearing of several other grouper species did not occur during E. marginatus culture. Notochord flexion, with initial ossification of the caudal‐fin supporting elements, started at 6·6 mm L_T. At this stage the major melanophores, preopercular, dorsal and pelvic spines and mandibular teeth were already present. Transformation of larvae into juveniles occurred when larvae averaged 13·8 mm L_T. Juveniles with a mean L_T of 20·1 mm started to settle and most of them were benthic with a mean L_T of 26·8 mm.     

Studies on the behaviour of Pseudomonas fluorescens biofilms after Ortho-phthalaldehyde treatment

A relatively novel biocide, ortho-phthalaldehyde (OPA), was tested to control biofilms formed by Pseudomonas fluorescens on stainless steel surfaces. The toxic action of OPA was assessed in terms of inactivation and removal of the biofilm by means of, respectively, the determination of the respiratory activity and the variation in the dry weight of the biofilms. For comparison, the activity of OPA against suspended bacteria was also evaluated. The results showed that higher concentrations of OPA and longer exposure times are needed to inactivate P. fluorescens biofilms than planktonic populations, thus denoting that sessile bacteria have a reduced susceptibility to OPA. This appears to be associated with the reaction with the proteins of the matrix, as demonstrated by the reduction of the antimicrobial action of OPA in the presence of a protein (bovine serum albumin). The application of OPA appeared to cause little effect in the removal of biofilms from the metal slides since the mass of biofilm that remained on the surfaces, after biocide treatment, was within the same range as those observed in the control tests. These results suggest that, with OPA application, biofilms can be inactivated but stay attached to the surfaces, decreasing thereby the success of the chemical treatment.