Auxin metabolism and rooting in young and mature clones of Sequoia sempervirens

The capacity of young and mature Sequoia sempervirens clones to produce roots in vitro was studied after wounding and indole-3-butyric acid (IBA) treatments. Rooting was not observed in mature or in young cuttings cultivated for 30 days in medium without IBA. The presence of 25 μ M IBA in the medium resulted in the appearance of roots at the base of the cuttings. More roots appeared and grew faster on cuttings of the young than on the mature clone. This difference in rooting capacity between young and mature cuttings may be related to differences in the hormone levels at the base of the 5 mm long cuttings during the first 4 days of the root inductive period. After HPLC fractionation. IAA. IBA and related compounds, including indole-3-aspartic acid (IAAsp) and IBA-glucose ester (IBA-GE), were determined by MS and MS-MS and their levels measured by ELISA. Another immunoreactive compound was also found and determined to be N,N-dimethyltryptophan (DMT), a compound previously reported to inhibit auxin-enhanced ethylene production. Wounding of the stem without IBA treatment revealed a transient increase in IAA, IAAsp and DMT levels in young cuttings while a dramatic increase in the levels of DMT was observed in mature cuttings. Following IBA treatment. IAA levels increased in both clones, but higher levels were measured in the young than in the mature clone. IBA and IBA-GE were also found but in higher levels in the mature clone. Thus, the difficult-to-root mature clone differs from the young clone in its auxin metabolism.     

Pilot-scale production of mosquitocidal toxins by Bacillus thuringiensis and Lysinibacillus sphaericus under solid-state fermentation

Mosquitocidal toxins of Bacillus thuringiensis israelensis (Bti) and Lysinibacillus sphaericus 14N1 (Ls14N1) were produced under solid-state fermentation using agro-industrial wastes. Sugar beet pulp–sesame meal (1:1) and wheat germ meal–linen meal (1:1) at 9% were the efficient substrate mixtures for the growth and toxin production of Bti and Ls14N1, respectively. Bti was more active after the addition of beef extract (0.2%) or yeast extract (0.5%) to the medium. On the other hand, the addition of yeast extract (0.2%) or NYSM salts (2%) significantly enhanced the toxicity produced by Ls14N1. The optimum conditions for the maximum toxicity of Bti were at pH 7–8, 20–30% moisture, 4–10% inoculum and 7 days incubation. For Ls14N1, the best conditions were pH 6.5–7.5, 20–30% moisture, 4–10% inoculum and 5 days incubation. It was found that the best thickness of carrier-substrates in the plate (15?cm in diameter) for the maximum mosquitocidal activity was about 0.5?cm for Bti and 0.5–1?cm for Ls14N1. Pilot-scale production in aluminium trays applying the above conditions showed a decrement of toxicity of fermented cultures and some plates were contaminated. These problems were dissolved by reducing the moisture content to 15%, increasing inoculum to 10% and manual agitation of trays every-day.     

A comparative study on recurrent blooms of Alexandrium minutum in two Mediterranean coastal areas

Alexandrium minutum is a toxic dinoflagellate widespread along the Mediterranean coasts. This species is frequently detected year-round at low concentrations within the Mediterranean basin. However, it only proliferates recurrently in some localities. Two affected areas are the Catalan and Sicilian coasts. In order to identify the factors determining the A. minutum blooms in the Mediterranean Sea, we compare the bloom conditions in two harbours: Arenys de Mar (Catalan coast, Spain) and Syracuse (Sicily, Italy), during 2002–2003. Arenys de Mar harbour is a fishing and leisure harbour and receives an input of freshwater rich in nutrients. Likewise, the Syracuse harbour – located on the Ionian coast of Sicily – is subject to freshwater inputs. Some points of this site are used for productive activities such as shellfish farming. A. minutum from the two areas studied were morphologically and genetically identical. In both sites, recurrent blooms take place from winter to spring. Surface water temperatures and salinities during A. minutum bloom events were 12–14.5 °C and 32–38, and 16–24 °C and 32–37.7 for Arenys and Syracuse, respectively. During the blooms, the spatial distribution of A. minutum in the two harbours, the physicochemical characteristics and the phytoplankton community were studied. Similarities in composition of the phytoplankton community were evidenced, with a clear dominance of dinoflagellates over the other taxa. In Arenys, the second dominant species was Prorocentrum micans followed by Scrippsiella spp. and Dinophysis sacculus. The same species were found in Syracuse although P. triestinum, and alternatively Lingulodinium polyedrum, reached cell densities much higher than the other dinoflagellates giving marked water discolourations.     

Development of a qualitative PCR method for the Alexandrium spp. (Dinophyceae) detection in contaminated mussels (Mytilus galloprovincialis)

Paralytic shellfish poisoning (PSP) is a syndrome caused by the consumption of shellfish contaminated with neurotoxins produced by organisms of the marine dinoflagellate genus Alexandrium. A. minutum is the most widespread species responsible for PSP in the Western Mediterranean basin. The standard monitoring of shellfish farms for the presence of harmful algae and related toxins usually requires the microscopic examination of phytoplankton populations, bioassays and toxin determination by HPLC. These procedures are time-consuming and require remarkable experience, thus limiting the number of specimens that can be analyzed by a single laboratory unit. Molecular biology techniques may be helpful in the detection of target microorganisms in field samples. In this study, we developed a qualitative PCR assay for the rapid detection of all potentially toxic species belonging to the Alexandrium genus and specifically A. minutum, in contaminated mussels. Alexandrium genus-specific primers were designed to target the 5.8S rDNA region, while an A. minutum species-specific primer was designed to bind in the ITS1 region. The assay was validated using several fixed seawater samples from the Mediterranean basin, which were analyzed using PCR along with standard microscopy procedures. The assay provided a rapid method for monitoring the presence of Alexandrium spp. in mussel tissues, as well as in seawater samples. The results showed that PCR is a valid, rapid alternative procedure for the detection of target phytoplankton species either in seawater or directly in mussels, where microalgae can accumulate.     

A combined CaMKII inhibition and mineralocorticoid receptor antagonism via eplerenone inhibits functional deterioration in chronic pressure overloaded mice

In the diseased and remodelled heart, increased activity and expression of Ca^2+/calmodulin‐dependent protein kinase II (CaMKII), an excess of fibrosis, and a decreased electrical coupling and cellular excitability leads to disturbed calcium homeostasis and tissue integrity. This subsequently leads to increased arrhythmia vulnerability and contractile dysfunction. Here, we investigated the combination of CaMKII inhibition (using genetically modified mice expressing the autocamtide‐3‐related‐peptide (AC3I)) together with eplerenone treatment (AC3I‐Epler) to prevent electrophysiological remodelling, fibrosis and subsequent functional deterioration in a mouse model of chronic pressure overload. We compared AC3I‐Epler mice with mice only subjected to mineralocorticoid receptor (MR) antagonism (WT‐Epler) and mice with only CaMKII inhibition (AC3I‐No). Our data show that a combined CaMKII inhibition together with MR antagonism mitigates contractile deterioration as was manifested by a preservation of ejection fraction, fractional shortening, global longitudinal strain, peak strain and contractile synchronicity. Furthermore, patchy fibrosis formation was reduced, potentially via inhibition of pro‐fibrotic TGF‐β/SMAD3 signalling, which related to a better global contractile performance and a slightly depressed incidence of arrhythmias. Furthermore, the level of patchy fibrosis appeared significantly correlated to eplerenone dose. The addition of eplerenone to CaMKII inhibition potentiates the effects of CaMKII inhibition on pro‐fibrotic pathways. As a result of the applied strategy, limiting patchy fibrosis adheres to a higher synchronicity of contraction and an overall better contractile performance which fits with a tempered arrhythmogenesis.     

Innate immunity orchestrates the mobilization and homing of hematopoietic stem/progenitor cells by engaging purinergic signaling—an update

Purinergic Signalling - Bone marrow (BM) as an active hematopoietic organ is highly sensitive to changes in body microenvironments and responds to external physical stimuli from the surrounding...     

Soil amendment interacts with invasive grass and drought to uniquely influence aboveground versus belowground biomass in aridland restoration

Water‐holding soil amendments such as super‐absorbent polymer (SAP) may improve native species establishment in restoration but may also interact with precipitation or invasive species such as Bromus tectorum L. (cheatgrass or downy brome) to influence revegetation outcomes. We implemented an experiment at two sites in Colorado, U.S.A., in which we investigated the interactions of drought (66% reduction of ambient rainfall), B. tectorum seed addition (BRTE, 465 seeds/m²), and SAP soil amendment (25 g/m²) on initial plant establishment and 3‐year aboveground and belowground biomass and allocation. At one site, SAP resulted in higher native seeded species establishment but only with ambient precipitation. However, by the third year, we detected no SAP effects on native seeded species biomass. Treatments interacted to influence aboveground and belowground biomass and allocation differently. At one site, a SAP × precipitation interaction resulted in lower belowground biomass in plots with SAP and drought (61.7 ± 7.3 g/m²) than plots with drought alone (91.6 ± 18.1 g/m²). At the other site, a SAP × BRTE interaction resulted in higher belowground biomass in plots with SAP and BRTE (56.6 ± 11.2 g/m²) than BRTE alone (35.0 ± 3.7 g/m²). These patterns were not reflected in aboveground biomass. SAP should be used with caution in aridland restoration because initial positive effects may not translate to long‐term benefits, SAP may uniquely influence aboveground versus belowground biomass, and SAP can interact with environmental variables to impact developing plant communities in positive and negative ways.     

The phylogenetic range of bacterial and viral pathogens of vertebrates

Many major human pathogens are multihost pathogens, able to infect other vertebrate species. Describing the general patterns of host–pathogen associations across pathogen taxa is therefore important to understand risk factors for human disease emergence. However, there is a lack of comprehensive curated databases for this purpose, with most previous efforts focusing on viruses. Here, we report the largest manually compiled host–pathogen association database, covering 2,595 bacteria and viruses infecting 2,656 vertebrate hosts. We also build a tree for host species using nine mitochondrial genes, giving a quantitative measure of the phylogenetic similarity of hosts. We find that the majority of bacteria and viruses are specialists infecting only a single host species, with bacteria having a significantly higher proportion of specialists compared to viruses. Conversely, multihost viruses have a more restricted host range than multihost bacteria. We perform multiple analyses of factors associated with pathogen richness per host species and the pathogen traits associated with greater host range and zoonotic potential. We show that factors previously identified as important for zoonotic potential in viruses—such as phylogenetic range, research effort, and being vector‐borne—are also predictive in bacteria. We find that the fraction of pathogens shared between two hosts decreases with the phylogenetic distance between them. Our results suggest that host phylogenetic similarity is the primary factor for host‐switching in pathogens.