When introduced equals invasive: normative use of “invasive” with ascidians

This study aimed to understand the use of “invasive species” as a normative concept and discuss its implications in conservation science, using introduced ascidians worldwide as model species. A specific search in Web of Science was performed and articles suitable for analysis were selected. Each article was classified according to the type of environment, species under study, type of effects and spread that ascidians are linked to. Most of the 184 articles analysed did not consider dispersal or effects as study subject (82 and 71%, respectively). Most research was conducted in laboratory conditions (41%) or human-made environments (32%) or indicating few escapes to natural environments. Almost half of the articles (47%) were made with the six more conspicuous introduced ascidians and this raised to 70% while considering articles that worked with two or more (pooled) species. The normative use of “invasive” is widely used regarding introduced ascidians. Spread and effects, necessary conditions to consider a species as invasive, are notoriously understudied. Most research was not conducted in natural environments and over a few species, weakening the perception of introduced ascidians as a conservation problem. To discuss the extent of the normative use of invasion science is important to distinguish two phenomena: are some species intrinsically problematic for conservation (i.e. invasive) or is the movement of non-native species (i.e. biological invasion) the conservation problem? By using invasive as a normative concept, we risk ending with a weakened concept potentially hindering the progress of invasion science.     

Photomixotrophic cultures of blueberries (<Emphasis Type="Italic">Vaccinium corymbosum</Emphasis>) accumulate or release phenylpropanoids via inductive treatments

The in vitro production of phenylpropanoids has been studied in temporary immersion bioreactors (TIBs) cultures of blueberries (Vaccinum corymbosum) supplemented with 0.4 MPa CO₂, light intensity of 150 μM/m²/s, and induced with ABA (4 mM) and H₂O₂ (5 mM). Results demonstrated differences in the accumulation and/or the release of patterns of metabolites. In TIBs plus ABA, a reddish-maroon color was consistent with the accumulation of phenolics, where shoots formed clusters without internodal segments. While in TIBs plus H₂O₂, the phenylpropanoids were released into the culture medium. In both cases, experimental treatments with sucrose-reduced medium displayed the highest phenylpropanoids values, in contrast with the controls (conventional culture). Altogether, differential expressions of genes, linked to key pathways as photosynthesis, phenylpropanoids, and oxidative burst, could corroborate for the increase in the phenolics production in parallel with an improvement of photosynthesis in photomixotrophic culture.     

Selective Chronic Sodium or Chloride Depletion Specifically Modulates Subfornical Organ Atrial Natriuretic Peptide Receptor Number in Young Rats

1. We studied the effects of selective chronic sodium depletion of chloride depletion on atrial natriuretic peptide receptor number in the subfornical organ and paraventricular nucleus of young rats.2. Sodium or chloride depletion decreased plasma levels of atrial natriuretic peptide, increased plasma renin activity, and induced extracellular fluid volume contraction. Chloride depletion induced more significant changes in extracellular fluid volume contraction than sodium depletion.3. In the subfornical organ, atrial natriuretic peptide receptor number significantly decreased (30%) after sodium depletion, while chloride depletion induced a smaller, not statistically significant decrease. Conversely, atrial natriuretic peptide receptors located in the paraventricular nucleus of young rats were not significantly affected by sodium or chloride depletion.4. Water deprivation reversed the decrease in atrial natriuretic peptide receptors produced by sodium depletion. Water-deprived sodium-depleted rats actually had higher numbers of atrial natriuretic peptide receptors in the subfornical organ than control rats. These changes were associated with severe extracellular fluid volume contraction and up regulation of brain vasopressin mRNA steady-state levels. Thus, the direction of change in the number of subfornical organ atrial natriuretic peptide receptors was dependent on the degree of extracellular fluid volume contraction.5. Our results suggest that atrial natriuretic peptide receptors located in the subfornical organ, and not in the paraventricular nucleus, are selectively regulated by sodium depletion and extracellular fluid volume contraction.     

Combination of humans,climate, and vegetation change triggered Late Quaternary megafauna extinction in the Última Esperanza region,southern Patagonia,Chile

South America lost around 52 genera of mammals during a worldwide event known as the Late Quaternary Extinction episode. More than 80% of South American mammals weighing > 44 kg succumbed. Analysis of the megafaunal extinction chronology in relation to human arrival and major climate changes have revealed slightly different extinction patterns in different eco‐regions of the continent, highlighting the importance of detailed regional analysis in order to understand how the possible drivers of extinction operated. Here we present an analysis of the megafaunal extinction in the Última Esperanza (UE) area of southwestern Patagonia, Chile. We have compiled a comprehensive chronology of megafaunal extinctions and earliest human occupation between 18–7 cal ka BP, based on radiocarbon dates from published literature. We calculated confidence intervals using the GRIWM method to estimate the times of human arrival and megafaunal local extinctions, and then compared these events to the timing of major climate and vegetation changes, fire frequency increase, and the Reclús volcanic eruption. Our results suggest that a combination of human impacts and climate–vegetation change drove megafaunal extinctions in the UE area, with the balance of factors being taxon specific; the volcanic eruption does not seem to have exacerbated extinctions. Competition between humans and mega‐carnivores seems to be the most plausible cause for the extinction of the mega‐carnivores. Coexistence of humans with extinct horses, extinct camels, and mylodonts for several thousand years rules out a scenario of blitzkrieg overkill of megafauna by humans. The transition of vegetation from cold grasslands to Nothofagus forests corresponds with the disappearance of Hippidion saldiasi and Lama cf. owenii. The later full establishment of Nothofagus forests and an increasing fire frequency coincided with the disappearance of mylodonts. A climate‐driven reduction of open environments plausibly reduced herbivore's populations making them susceptible to local extinction.     

Estimation of <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> biomass concentration from chord length distribution data

A novel method to estimate the concentration of Chlamydomonas reinhardtii biomass was developed. The method employs the chord length distribution information gathered by means of a focused beam reflectance probe immersed in the culture sample and processes the data through a feedforward multilayer perceptron. The multilayer perceptron architecture was systematically optimised through the application of a simulated annealing algorithm. The method developed can predict the concentration of microalgae with acceptable accuracy and, with further development, it could be implemented online to monitor the aggregation status and biomass concentration of microalgal cultures.     

Revisiting the use of the invasive species concept: An empirical approach

Invasion science has not been developed without controversies. Two questions that are still unsolved are: what is an invasive species?, and are invasive species an inherent conservation problem? These questions have led to discussions about effects versus origins. In contrast to the definitional problems, a unified framework describing invasion as a step‐by‐step process has been widely accepted. I conducted a bibliographic search with two separate databases searching for (i) evidence of less use of controversial terms over time; (ii) how many articles defined ‘invasive species’; (iii) the criteria used to define a species as invasive; and (iv) in which stage of the invasion continuum were species labelled as invasive located. My results show that controversial terms are widely used, that authors rarely define ‘invasive species’ and, often, it is very complicated to determine which criterion they used. In addition, only a fraction of the species labelled as invasive could be classified as such according to the unified framework of invasion stages. This is not a merely semantic issue, because invasive is a strong and value‐laden term that is used to guide environmental agendas. The uncritical use of a key concept could hamper research, complicate communication among peers and produce mixed results.     

Calcium ion-dependent p-nitrophenyl phosphate phosphatase activity and calcium ion-dependent adenosine triphosphatase activity from human erythrocyte membranes

In the presence of ATP and of Mg(2+), human erythrocyte membranes show a phosphatase activity towards p-nitrophenyl phosphate which is activated by low concentrations of Ca(2+). The effect of Ca(2+) is strongly enhanced if either K(+) or Na(+) is also present. Activation of the p-nitrophenyl phosphate phosphatase by Ca(2+) reaches a half-maximum at about 8mum-Ca(2+) and is apparent only when the ion has access to the inner surface of the cell membrane. Ca(2+)-dependent phosphatase activity can only be observed if ATP is at the inner surface of the cell membrane, and the presence of ATP seems to be absolutely necessary, since either its removal or its replacement by other nucleoside triphosphates abolishes the activating effect of Ca(2+). The properties of the (ATP+Ca(2+))-dependent phosphatase are very similar to those of the Ca(2+)-dependent ATPase (adenosine triphosphatase), also present in erythrocyte membranes, which probably is involved in Ca(2+) transport in erythrocytes. The similarities suggest that both activities may be properties of the same molecular system. This view is further supported by the fact that p-nitrophenyl phosphate inhibits to a similar extent Ca(2+)-dependent ATPase activity and ATP-dependent Ca(2+) extrusion from erythrocytes.     

Catalase Stability in Amorphous and Supercooled Media Related to Trehalose- Water- Salt Interactions

Sugars are the most common excipients added to pharmaceutical and biotechnological formulations as protein protectants due to their adequate physicochemical properties, low toxicity, high purity and low cost. However, a second excipient is generally required to extend their protection in supercooled media. The effect of electrolytes is of special interest because of their universal presence in biological systems, their major influence on water structure, and their capability to interact with biomolecules. The purpose of the present work was to analyze the effect of different salts on the stability of catalase in amorphous (glassy and supercooled) trehalose matrices. Trehalose-Mg²⁺ system was better than trehalose alone to protect the enzyme both during freeze-drying and later storage at low RH (22%). The stabilizing effect observed for certain salts in these systems was not related with an increase of the T_g value. Under conditions at which trehalose crystallizes (43 %RH), salts (especially Mg²⁺) were detrimental since the enzyme became confined in a salt-concentrated region. Protein denaturation and aggregation were analyzed through differential scanning calorimetry in order to correlate activity changes with physical changes. Trehalose systems without salt and Mg²⁺-containing systems showed almost no aggregation after denaturation, in agreement with the thermal stability of the enzyme. Thus, the two major parameters related to enzyme stability in freeze-dried non-crystallized systems are: enzyme characteristics (type, quaternary structure) and salt-protein specific interactions.