Drought-induced dieback of Pinus nigra: A tale of hydraulic failure and carbon starvation

Ongoing climate change is apparently increasing tree mortality rates, and understanding mechanisms of drought-induced tree decline can improve mortality projections. Differential drought impact on conspecific individuals within a population has been reported, but no clear mechanistic explanation for this pattern has emerged. Following a severe drought (summer 2012), we monitored over a 3-year period healthy (H) and declining (D) Pinus nigra trees co-occurring in a karstic woodland to highlight eventual individual-specific physiological differences underlying differential canopy dieback. We investigated differences in water and carbon metabolism, and xylem anatomy as a function of crown health status, as well as eventual genotypic basis of contrasting drought responses. H and D trees exploited the same water pools and relied on similar hydraulic strategies to cope with drought stress. Genetic analyses did not highlight differences between groups in terms of geographical provenance. Hydraulic and anatomical analyses showed conflicting results. The hydraulic tracheid diameter and theoretical hydraulic conductivity were similar, but D trees were characterized by lower water transport efficiency, greater vulnerability to xylem conduit implosion and reduced carbohydrate stores. Our results suggest that extreme drought events can have different impacts on conspecific individuals, with differential vulnerability to xylem embolism likely playing a major role in setting the fate of trees under climate change

Note sulla reazione biologica ai punti di sutura

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Physiological and molecular responses of bivalves to toxic dinoflagellates

Dinoflagellates and other microalgae can produce a wide spectrum of toxic molecules, which are the main responsible of shellfish poisoning syndromes. During seasonal harmful algal blooms (HABs), many filter-feeding marine invertebrates, including bivalve molluscs, can accumulate phycotoxins at extremely high levels, thus representing a serious threat to human health. Furthermore, HABs also have a severe impact on the aquaculture sector due to the forced prolonged closure of large harvesting areas. Although the targets and mechanism of action of many phycotoxins have been extensively studied on vertebrate model organisms, so far just a little attention has been focused on their effects on marine invertebrates. Here we provide an overview about the molecular response of marine bivalves to phycotoxins, with a particular focus on toxins produced by dinoflagellates. Even though large-scale genomic and proteomic approaches on molluscs are still hindered by the limited molecular knowledge of these organisms, a few studies exploiting the most recent technological advances provide promising perspectives for a better comprehension of the mechanisms involved in shellfish toxicity and for the identification of molecular markers of contamination

Physiological and molecular responses of bivalves to toxic dinoflagellates

Dinoflagellates and other microalgae can produce a wide spectrum of heterogeneous toxic molecules, which are the main responsible of shellfish poisoning syndromes. During seasonal harmful algal blooms (HABs), many filter-feeding marine invertebrates, including bivalve mollusks, can accumulate phycotoxins at extremely high levels, thus representing a serious threat to human health. Furthermore, HABs also have a severe impact on the aquaculture sector due to the forced prolonged closure of large harvesting areas. Although the targets and mechanism of action of many phycotoxins have been extensively studied on vertebrate model organisms, so far just a little attention has been focused on their effects on marine invertebrates. Here we provide an overview about the molecular response of marine bivalves to phycotoxins, with a particular focus on toxins produced by dinoflagellates. Even though large-scale genomic and proteomic approaches on mollusks are still hindered by the limited molecular knowledge of these organisms, a few studies exploiting the most recent technological advances provide promising perspectives for a better comprehension of the mechanisms involved in shellfish toxicity and for the identification of molecular markers of contamination

Reazione biologica ai punti di sutura

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Genomics in bivalve aquaculture

No abstrac

SARS-Cov-2RNA found on particulate matter of Bergamo in Northern Italy: First evidence

Background: The burden of COVID-19 was extremely severe in Northern Italy, an area characterized by high concentrations of particulate matter (PM), which is known to negatively affect human health. Consistently with evidence already available for other viruses, we initially hypothesized the possibility of SARS-CoV-2 presence on PM, and we performed a first experiment specifically aimed at confirming or excluding this research hyphotesys. Methods: We have collected 34 PM10 samples in Bergamo area (the epicenter of the Italian COVID-19 epidemic) by using two air samplers over a continuous 3-weeks period. Filters were properly stored and underwent RNA extraction and amplification according to WHO protocols in two parallel blind analyses performed by two different authorized laboratories. Up to three highly specific molecular marker genes (E, N, and RdRP) were used to test the presence of SARS-CoV-2 RNA on particulate matter. Results: The first test showed positive results for gene E in 15 out of 16 samples, simultaneously displaying positivity also for RdRP gene in 4 samples. The second blind test got 5 additional positive results for at least one of the three marker genes. Overall, we tested 34 RNA extractions for the E, N and RdRP genes, reporting 20 positive results for at least one of the three marker genes, with positivity separately confirmed for all the three markers. Control tests to exclude false positivities were successfully accomplished. Conclusion: This is the first evidence that SARS-CoV-2 RNA can be present on PM, thus suggesting a possible use as indicator of epidemic recurrence