The genus Acacia as invader: the characteristic case of Acacia dealbata Link in Europe

? We review current knowledge about the biology of the genus Acacia, and Acacia dealbata Link (silver wattle) in particular, as an invader in Europe, focusing on (i) the biology of the genus Acacia; (ii) biological attributes that are important for the invasiveness of the genus and A. dealbata; (iii) possible hypotheses for the invasion success; and (iv) control methods.

? Several Australian wattles have been recorded as naturalized in Europe. Acacia has attained pest proportions in certain habitats and protected sites (notably coastal dunes, river courses, natural parks and biosphere reserves).

? The spread of Acacia dealbata seems to be assisted by human interference such as soil disturbance and severe fires. The biological attributes favoring invasion by A. dealbata include tolerance of changing soil conditions, the ability to take advantage of environmental disturbance, phenotypic plasticity, vegetative reproduction, fire tolerance and allelopathic potential.

? Different hypotheses explaining invasiveness and transition between invasion steps related to biological attributes as the key factor for A. dealbata invasion are discussed. Effects on the biodiversity of native flora are little understood and studies of suppression of autochthonous species are needed. It is desirable that further studies comparing Acacia at field sites in their native and exotic range should be done.

? Understanding the biology of invasive wattles in Europe is the first step to an effective control method. Studies comparing plant invaders at field sites in their native and invaded areas seem to be most appropriate in order to be able to attack the most vulnerable stages.

     

Afforestation of a trace-element polluted area in SW Spain: woody plant performance and trace element accumulation

Trace element soil pollution can have ecotoxic effects on plants, which could negatively affect the restoration of a degraded area. In this work, we studied the revegetation success in different sites within a trace element-polluted area (Guadiamar River Valley, SW Spain). We analysed the survival and growth patterns of afforested plants of seven Mediterranean woody species, and their relation to soil pollution, over 3 years. We also analysed the trace element accumulation in the leaves of these species. The area was polluted mainly by As, Cd, Cu, Pb and Zn (soil total concentrations up to 250, 3.6, 236, 385 and 510 mg kg⁻¹, respectively). The woody plant performance was very different between sites and between species; in the riparian sites, plant survival rates were nearly 100%, while in the upland terrace sites species such as Quercus ilex and Ceratonia siliqua showed the lowest survival rates (less than 30%) and also the lowest relative growth rates. There were no significant relationships between plant performance and soil pollution in the riparian sites, while in the upland sites mortality, but not growth, was related to soil pollution, although that could be an indirect effect of different substrate alteration between sites. The accumulation of soil pollutants in the studied plants was low, with the exception of Salicaceae species, which accumulated Cd and Zn in the leaves above 1 and 200 mg kg⁻¹, respectively. We discuss the results with regard to the afforestation of trace-element polluted areas.     

Changing face of microglia

Microglia are resident brain cells that sense pathological tissue alterations. They can develop into brain macrophages and perform immunological functions. However, expression of immune proteins by microglia is not synonymous with inflammation, because these molecules can have central nervous system (CNS)-specific roles. Through their involvement in pain mechanisms, microglia also respond to external threats. Experimental studies support the idea that microglia have a role in the maintenance of synaptic integrity. Analogous to electricians, they are capable of removing defunct axon terminals, thereby helping neuronal connections to stay intact. Microglia in healthy CNS tissue do not qualify as macrophages, and their specific functions are beginning to be explored.     

Grazing intensity affects forage accumulation and persistence of Marandu palisadegrass in the Brazilian savannah

This 3‐year study evaluated the effects of grazing intensity on herbage and steer responses in continuously stocked Brachiaria brizantha cv. Marandu pasture in the Brazilian savanna. Treatments consisted of three grazing intensity levels, characterized by canopy heights of 15, 30 and 45 cm, measured twice per week. Responses variables included tiller population density (TPD), herbage accumulation rate (HAR) and body weight gain per area (WGA). A decline in TPD (1,237 vs. 767 tillers/m²) was observed from the first to the third grazing years, which influenced the HAR from the first to the third years (90.1 vs. 52.4 kg ha^?1 day^?1). A marked decline in body WGA (541 vs. 276 kg ha^?1 year^?1) was observed along the three years in pastures managed at a height of 15 cm, indicating that this is an unstable condition for Marandu palisadegrass pasture. HAR was similar for pastures managed at 30 or 45 cm and was relatively stable during the experimental period, averaging 91.8 and 99.1 kg ha^?1 day^?1 respectively. Body WGA was similar and constant throughout the experimental period for pastures managed at 30 (596 kg ha^?1 year^?1) and 45 cm (566 kg ha^?1 year^?1). Maintaining continuously stocked Marandu palisadegrass pastures at a 15 cm canopy height should be avoided due to long‐term decreases in plant persistence and animal body WGA, particularly when soil P is below critical levels at pasture establishment and during pasture utilization.     

Bioactive Compounds from Theobroma cacao: Effect of Isolation and Safety Evaluation

Plant Foods for Human Nutrition - Plants, including most food and feed plants, produce a broad range of bioactive chemical compounds. Among these compounds, polyphenols are reported to provide...     

Calcium alginate capsules for oral administration of fish probiotic bacteria: assessment of optimal conditions for encapsulation

The application of probiotics in aquaculture represents a promising alternative for disease prevention. These microorganisms must survive adverse conditions during handling and storage to be administered in high concentrations to the host. This is especially important when stressful conditions, such as low water contents, are present in animal feed. Bacterial encapsulation has been used to maintain probiotic viability in human food; however, the usefulness of the encapsulation techniques in animal feed needs to be evaluated. In the present study, optimal conditions for encapsulation in alginate of a fish probiotic Shewanella putrefaciens strain (Pdp11) have been determined. Different alginate (1%, 2%, 3% and 4% w/v) and calcium chloride (0.5%, 1% 2% and 3% w/v)concentrations were used to elaborate alginate beads. The results obtained indicate that S. putrefaciens Pdp11 can be encapsulated successfully in calcium alginate beads. The percentages of encapsulated cells were above 80%, the lowest efficiency rates corresponding to high calcium availability (3%). In addition, capsules containing viable S. putrefaciens Pdp11 can be stored at 4 °C for at least 1 month, survival rates being above 90%. On the contrary, storage of the capsules at 22 °C resulted in 40% viability loss within 30 days. Finally, the survival of encapsulated probiotics through fish gastrointestinal tract has been demonstrated.     

Identification of a photolabile period for reducing sexual maturation in juvenile male sea bass (Dicentrarchus labrax) by means of a continuous light regime

The objective of this study was to identify a photolabile period suitable for reducing precocious gonadal maturation in juvenile male sea bass (Dicentrarchus labrax) through the exploration of discrete windows of continuous light (LL), 1?C2?months in duration, in late summer-early autumn. Somatic growth, 11-ketotestosterone plasma levels, and the rates of testicular maturation and spermiation were analyzed to evaluate the effect of the applied photoperiodic regimes. Three LL treatments, with duration of 2?months each, were previously screened between the months of August and November. Administration of LL during the October?CNovember period failed to show any differential effects in reducing early maturation, as compared to the simulated natural photoperiod. However, the August?CSeptember period was considered to be a likely candidate for photolability. To define this photolabile period, four LL treatments with duration of 1?month were then screened within the same late summer period. Our results demonstrate that the time interval including the month of September is the most sensitive photolabile period in order to reduce precocious gametogenesis in sea bass.     

Biosynthetic Studies on Water-Soluble Derivative 5c (DTX5c)

The dinoflagellate Prorocentrum belizeanum is responsible for the production of several toxins involved in the red tide phenomenon known as Diarrhetic Shellfish Poisoning (DSP). In this paper we report on the biosynthetic origin of an okadaic acid water-soluble ester derivative, DTX5c, on the basis of the spectroscopical analysis of ¹³C enriched samples obtained by addition of labelled sodium [l-¹³C], [2-¹³C] acetate to artificial cultures of this dinoflagellate.     

Mediterranean fruit fly suppression using chemosterilants for area‐wide integrated pest management

BACKGROUND: The chemosterilisation technique has been demonstrated to reduce the population and fruit damage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in citrus orchards. Field trials showed efficacy by reducing the fruit fly population, which was progressively achieved by continuous application of lufenuron to several generations. Different authors have suggested that field trials should be carried out in isolated or wide areas in order to reduce fruit fly intrusion and obtain best results. To this end, a wide‐area trial over 3600 hectares has been under investigation in Valencia (Spain) since 2002 to validate the chemosterilisation technique against the fruit fly. The whole area was treated with 24 traps ha^?1, using more than 86 000 traps in the field trial. RESULTS: A continuous decrease in fruit fly population was observed over the 4 years under trial. Moreover, results showed a significant reduction in persimmon damage in the chemosterilant treatment area compared with a malathion aerial treatment area. In the case of citrus damage, no significant differences were obtained between malathion and chemosterilant treatments. CONCLUSION: The chemosterilant method reduces Mediterranean fruit fly populations, and therefore it is a candidate treatment to replace aerial treatments with insecticides in order to suppress this pest. In addition, the efficacy of chemosterilant treatment is increasing year after year. The possibility of using this technique combined with other control methods is discussed. Copyright © 2010 Society of Chemical Industry     

The effects of a regeneration felling on photosynthetic photon flux density and regeneration growth in a <Emphasis Type="Italic">Nothofagus pumilio</Emphasis> forest

Photosynthetic photon flux density (PPFD) during the growing season and regeneration growth (height and base stem diameter) were investigated in two natural stands in the Patagonian region of Chile, one without silvicultural management and another with a regenerative felling under a shelterwood system. PPFD was measured by means of fifteen sensors (quantum Li-190SA) installed in each stand and distributed within three canopy openness grades. Four regeneration plots (1 m²) were established around each sensor. In each of the plots, the height and base diameter of ten labelled plants within the upper regeneration layer were measured in the growing seasons 2001–2002 and 2002–2003. In the stand with regeneration felling total PPFD in the growing season was 2.5–2.9 times higher than in the stand without intervention. In both stands, total PPFD in the growing season increased by about 420 mmol/m² when the relative canopy, which was in the range between 30 and 70%, was reduced by 10%. An identical behaviour was observed for the height and base stem diameter increases reflecting a clear effect of intervention and canopy coverage on the magnitude of PPFD received by the regeneration and its development.