Modelling the introduction and spread of non‐native species: international trade and climate change drive ragweed invasion

Biological invasions are a major driver of global change, for which models can attribute causes, assess impacts and guide management. However, invasion models typically focus on spread from known introduction points or non‐native distributions and ignore the transport processes by which species arrive. Here, we developed a simulation model to understand and describe plant invasion at a continental scale, integrating repeated transport through trade pathways, unintentional release events and the population dynamics and local anthropogenic dispersal that drive subsequent spread. We used the model to simulate the invasion of Europe by common ragweed (Ambrosia artemisiifolia), a globally invasive plant that causes serious harm as an aeroallergen and crop weed. Simulations starting in 1950 accurately reproduced ragweed's current distribution, including the presence of records in climatically unsuitable areas as a result of repeated introduction. Furthermore, the model outputs were strongly correlated with spatial and temporal patterns of ragweed pollen concentrations, which are fully independent of the calibration data. The model suggests that recent trends for warmer summers and increased volumes of international trade have accelerated the ragweed invasion. For the latter, long distance dispersal because of trade within the invaded continent is highlighted as a key invasion process, in addition to import from the native range. Biosecurity simulations, whereby transport through trade pathways is halted, showed that effective control is only achieved by early action targeting all relevant pathways. We conclude that invasion models would benefit from integrating introduction processes (transport and release) with spread dynamics, to better represent propagule pressure from native sources as well as mechanisms for long‐distance dispersal within invaded continents. Ultimately, such integration may facilitate better prediction of spatial and temporal variation in invasion risk and provide useful guidance for management strategies to reduce the impacts of invasion.     

Munc13-4 is essential for cytolytic granules fusion and is mutated in a form of familial hemophagocytic lymphohistiocytosis (FHL3)

Secretion of cytolytic granules content at the immunological synapse is a highly regulated process essential for lymphocyte cytotoxicity. This process requires the rapid transfer of perforin containing lytic granules to the target cell interface, followed by their docking and fusion with the plasma membrane. Defective cytotoxicity characterizes a genetically heterogeneous condition named familial hemophagocytic lymphohistiocytosis (FHL), which can be associated with perforin deficiency. The locus of a perforin (+) FHL subtype (FHL3), observed in 10 patients, was mapped to 17q25. This region contains hMunc13-4, a member of the Munc13 family of proteins involved in vesicle priming function. HMunc13-4 mutations were shown to cause FHL3. HMunc13-4 deficiency results in defective cytolytic granule exocytosis, despite polarization of the secretory granules and docking with the plasma membrane. Expressed tagged hMunc13-4 localizes with cytotoxic granules at the immunological synapse. HMunc13-4 is therefore essential for the priming step of cytolytic granules secretion preceding vesicle membrane fusion.     

Directed differentiation of dendritic cells from mouse embryonic stem cells

Dendritic cells (DCs) are uniquely capable of presenting antigen to naive T cells, either eliciting immunity [1] or ensuring self-tolerance [2]. This property identifies DCs as potential candidates for enhancing responses to foreign [3] and tumour antigens [4], and as targets for immune intervention in the treatment of autoimmunity and allograft rejection [1]. Realisation of their therapeutic potential would be greatly facilitated by a fuller understanding of the function of DC-specific genes, a goal that has frequently proven elusive because of the paucity of stable lines of DCs that retain their unique properties, and the inherent resistance of primary DCs to genetic modification. Protocols for the genetic manipulation of embryonic stem (ES) cells are, by contrast, well established [5], as is their capacity to differentiate into a wide variety of cell types in vitro, including many of hematopoietic origin [6]. Here, we report the establishment, from mouse ES cells, of long-term cultures of immature DCs that share many characteristics with macrophages, but acquire, upon maturation, the allostimulatory capacity and surface phenotype of classical DCs, including expression of CD11c, major histocompatibility complex (MHC) class II and co-stimulatory molecules. This novel source should prove valuable for the generation of primary, untransformed DCs in which candidate genes have been overexpressed or functionally ablated, while providing insights into the earliest stages of DC ontogeny.     

The use of indigenous plant species and calcium phosphate for the stabilization of highly metal-polluted sites in southern Poland

Highly metal-polluted (Pb, Cd, Zn) soil from a non-ferrous mine and smelter site in southern Poland, further referred to as Waryski soil, was used to test indigenous plant species for stabilization effectiveness of heavy metals in soils. Results of pilot investigations with commercially available cultivars of plant species showed that these cultivars could not grow on this highly polluted soil even with the application of soil amendments to stabilize the heavy metals. Based on these results, mesocosm and field experiments with an indigenous, metal-tolerant ecotype of Deschampsia cespitosa from the Waryñski site were carried out. The mesocosm experiment showed that applications of calcium phosphate (3.8% w/w) as a heavy metal-stabilizing amendment decreased Cd and Zn concentrations 2 and 3-fold respectively in leachates, whereas lead content was not significantly changed. This decrease in the concentration of heavy metals in leachates was correlated with a lower accumulation of Pb, Cd and Zn in the roots and shoots of D. cespitosa, ecotype Waryñski. In the field experiment, lower accumulations of Cd in roots and shoots and Zn in shoots in the amendment added plot were observed during the second year of investigations. In the first growing season, D. cespitosa plant cover in the amendment enriched mesocosms ranged from 95 to 100%, compared to 10% in mesocosms without calcium phosphate. In the second year of the experiment, in non-amendment enriched mesocosms D. cespitosa was substituted with Cardaminopsis arenosa(95% cover). C. arenosa is an undesirable species for phytostabilization, as it accumulates high amounts of zinc and cadmium in its shoots, even thought it provided better growth cover in not amended soils. However, in amended mesocosms, soil surface cover by D. cespitosa was still very high (90%). Similar results were obtained in field experiments. Addition of calcium phosphate to the soil also resulted in excellent D. cespitosa root system development when compared to soils without amendment. In amended mesocosms, high plant cover and root system development significantly decreased the volume of leachates and improved water retention. These results indicate that the use of D. cespitosa, ecotype Waryski in combination with calcium phosphate as a heavy metals immobilizing agent is sufficient to restore a dense vegetative cover to highly heavy metal-polluted soil.     

SQUARE--determining reliable regions in sequence alignments

The Server for Quick Alignment Reliability Evaluation (SQUARE) is a Web-based version of the method we developed to predict regions of reliably aligned residues in sequence alignments. Given an alignment between a query sequence and a sequence of known structure, SQUARE is able to predict which residues are reliably aligned. The server accesses a database of profiles of sequences of known three-dimensional structures in order to calculate the scores for each residue in the alignment. SQUARE produces a graphical output of the residue profile-derived alignment scores along with an indication of the reliability of the alignment. In addition, the scores can be compared against template secondary structure, conserved residues and important sites.     

Evaluation of hexose and pentose in pre-cultivation of <Emphasis Type="Italic">Candida guilliermondii</Emphasis> on the key enzymes for xylitol production in sugarcane hemicellulosic hydrolysate

The evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii FTI 20037 yeast on xylose reductase (XR) and xylitol dehydrogenase (XDH) enzymes activities was performed during fermentation in sugarcane bagasse hemicellulosic hydrolysate. The xylitol production was evaluated by using cells previously growth in 30.0 gl^?1 xylose, 30.0 gl^?1 glucose and in both sugars mixture (30.0 gl^?1 xylose and 2.0 gl^?1 glucose). The vacuum evaporated hydrolysate (80 gl^?1) was detoxificated by ion exchange resin (A-860S; A500PS and C-150-Purolite^®). The total phenolic compounds and acetic acid were 93.0 and 64.9%, respectively, removed by the resin hydrolysate treatment. All experiments were carried out in Erlenmeyer flasks at 200 rpm, 30°C. The maximum XR (0.618 Umg _Prot ^?1 ) and XDH (0.783 Umg _Prot ^?1 ) enzymes activities was obtained using inoculum previously growth in both sugars mixture. The highest cell concentration (10.6 gl^?1) was obtained with inoculum pre-cultivated in the glucose. However, the xylitol yield and xylitol volumetric productivity were favored using the xylose as carbon source. In this case, it was observed maximum xylose (81%) and acetic acid (100%) consumption. It is very important to point out that maximum enzymatic activities were obtained when the mixture of sugars was used as carbon source of inoculum, while the highest fermentative parameters were obtained when xylose was used.     

Antifungal and physicochemical properties of Ocimum essential oil loaded in poly(lactic acid) nanofibers

Poly(lactic acid) (PLA) nanofibres containing different proportions of the essential oils from Ocimum basilicum L. and Ocimum gratissimum L. were prepared by solution blow spinning method. The essential oils were extracted by hydrodistillation and characterized by gas chromatography. MEV, contact angle, DSC and FTIR were used to characterize the nanofibres. The effect of bioative nanofibres on the growth of the fungus and on the production of ochratoxin A were evaluated using the fumigation test. Linalool, 1·8-cineole and camphor were the principal components of the essential oil from O. basilicum, and eugenol was the principal constituent in the oil from O. gratissimum. An increase in the average diameter of the nanofibres was observed with the addition of the essential oils. The essential oils acted as a plasticizer, resulting in a reduction in the crystallinity of the PLA. The encapsulation of essential oils in PLA nanofibres was verified by FTIR. An effective antifungal and antimicotoxygenic activity against Aspergillus ochraceus and Aspergillus westerdjikiae was observed for the bioative nanofibres. These results confirm the potential of PLA nanofibres containing the essential oils for the control of toxigenic fungi that cause the deterioration of food and are harmful to human health.     

Cytogenetic Studies on Workers of the Neotropical Ant Wasmannia auropunctata (Roger 1863) (Hymenoptera: Formicidae: Myrmicinae)

Wasmannia auropunctata is known as one of the worst invasive ants in the World. A cytogenetic study was conducted on two native populations from southeastern Bahia, Brazil. The analysis of the chromosomes observed in mitotic metaphases was made by a combination of methods: Giemsa conventional staining, chromomycin A3 (CMA3) and 4-6-diamidino-2-phenylindole (DAPI) fluorochrome staining, and acridine orange banding. The workers have all the karyotype 2n=32, with ten pairs of metacentric and six pairs of acrocentric chromosomes. One chromosome arm of the pair ten was positive for CMA3 and acridine orange, suggesting the occurrence of a nucleolar organizing region. This region is an interesting marker because is very conservative and seems to constitute an interesting specific taxonomic character. The pericentromeric region of many chromosomes was stained with DAPI, evidencing the occurrence of AT bases rich heterochromatin.     

Correction to: Lentinula edodes as a Source of Bioelements Released Into Artificial Digestive Juices and Potential Anti-inflammatory Material

Biological Trace Element Research - The original version of this article unfortunately contained a mistake.