Intraspecific trait variation and trade-offs within and across populations of a toxic dinoflagellate

Abstract Intraspecific trait diversity can promote the success of a species, as complementarity of functional traits within populations may enhance its competitive success and facilitates resilience to changing environmental conditions. Here, we experimentally determined the variation and relationships between traits in 15 strains of the toxic dinoflagellate Alexandrium ostenfeldii derived from two populations. Measured traits included growth rate, cell size, elemental composition, nitrogen uptake kinetics, toxin production and allelochemical potency. Our results demonstrate substantial variation in all analysed traits both within and across populations, particularly in nitrogen affinity, which was even comparable to interspecific variation across phytoplankton species. We found distinct trade-offs between maximum nitrogen uptake rate and affinity, and between defensive and competitive traits. Furthermore, we identified differences in trait variation between the genetically similar populations. The observed high trait variation may facilitate development and resilience of harmful algal blooms under dynamic environmental conditions

Trait measurements of 15 Alexandrium ostenfeldii strains isolated from two distinct locations

Trait measurements of 15 Alexandrium ostenfeldii strains isolated from two distinct location

Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield

Acutodesmus obliquus (SAG 276-1), a microalga with a resistant cell wall, was chosen as a benchmark strain for testing the effect of storage and pretreatment methods on methane yields during anaerobic digestion. A. obliquus was cultivated in sleevebag photobioreactors (batch cultivation). Biomass was centrifuged to a final total solid concentration of 91gL-1 and subjected to different treatments. The biomass was then subjected to biochemical methane potential tests. Among the different storage methods tested, freezing and freeze-drying resulted in significantly higher CH4 yields, i.e., 350 Nm3t-1 VSharvest (=normalized gas volume in m3 corrected to norm temperature and pressure per unit harvested volatile solids) (+53% CH4) and 291Nm3t-1 VSharvest (+29% CH4) compared to the fresh biomass (229 Nm3t-1 VSharvest). For pretreatments, the combined milling and enzyme approach (300 Nm3t-1 VSharvest, +57% CH4), ultrasonication (292 Nm3t-1 VSharvest, +52% CH4) and milling (289 Nm3t-1 VSharvest, +51% CH4) resulted in significantly higher CH4 conversion compared to the untreated control (191Nm3t-1 VSharvest). We found a significantly strong positive correlation between viable cell counts and CH4 yields, and a correlation with the solubilized chemical oxygen demand. Our study revealed that mechanical pretreatments were effective and resulted in highest CH4 yields. In addition, the effect of different storage methods must not be neglected.Austrian COMET program under grant number 834018. Republic of Austria and the Federal Provinces of Styria, Lower Austria and Burgenland. Co-funding from the industry partner Erber Group shall be highly acknowledged.Scopu

Two-stage cultivation of N-rich and N-deprived Acutodesmus obliquus biomass: Influence of cultivation and dewatering methods on microalgal biomass used in anaerobic digestion

Microalgae can be manipulated to accumulate certain cellular compounds of interest without the need for genetic modification - simply by controlling growth parameters such as nitrogen (N). Therefore, A. obliquus was batch-cultivated in a sleevebag photobioreactor system in N-deprived and N-rich medium to test the effect of N-status on CH4 yield under anaerobic digestion. Two different dewatering methods, i.e., centrifugation and sedimentation were applied to each resulting biomass. For the N-deprived biomass, cellular protein content dropped by 42–49%, and lipids increased up to 20% relative to the N-rich biomass. The highest CH4 yields were achieved with N-deprived, sedimented biomass (391 Nm3 t− 1 VS = normalized gas volume in m3 corrected to norm temperature and pressure per unit volatile solids), followed by N-rich sedimented biomass (361 Nm3 t− 1 VS). Centrifugation led to lower CH4 yields, where N-deprived biomass achieved 280 compared to 200 Nm3 t− 1 VS for N-rich microalgae. Our data indicate that valuable organic material was lost to the supernatant during the centrifugation step. We conclude that not only the N-status of cultivation, but also the biomass dewatering method has an instrumental effect on CH4 yield of microalgal biomass in anaerobic digestion.This work was performed in the frame of the Austrian COMET program under grant number 834018. It has received funding from the Republic of Austria and the Federal Provinces of Styria, Lower Austria and Burgenland. Co-funding from the industry partner Erber Group shall be highly acknowledged

Associated effects of storage and mechanical pre-treatments of microalgae biomass on biomethane yields in anaerobic digestion

The pre-treatment of microalgae cell walls is known to be a key factor to enhance methane (CH4) yields during anaerobic digestion. This study investigated the combined effects of two different biomass storage methods and physical pre-treatments on the anaerobic digestion for three different microalgae species. Acutodesmus obliquus, Chlorella vulgaris and Chlorella emersonii were cultivated in 80 L sleevebag photobioreactors (batch mode), and then subjected to different storage (cooling and freezing) and pre-treatment methods prior to anaerobic digestion using the biochemical methane potential (BMP) test. A. obliquus was selected to evaluate pre-treatment methods for further experimentation. Significantly higher CH4 yields of cooled (4 °C) A. obliquus biomass were achieved through ultrasonication (+53% CH4) and wet-milling (+51% CH4). These methods were then applied in follow-up experiments to cooled (4 °C) biomass of C. emersonii and A. obliquus. Ultrasonication again led to significantly higher CH4 yields for A. obliquus biomass (323 dm3 kg−1 CH4 yield calculated at standard gas conditions of 273 K, and 101.5 kPa per unit volatile solids, +41% CH4), and C. emersonii biomass (308 dm3 kg−1; +35% CH4). In a third experiment series, frozen A. obliquus and C. vulgaris biomass were thawed prior to pre-treatment and BMP-testing. Among all BMP tests, the highest CH4 yields were achieved with untreated, freeze-thawed C. vulgaris biomass (406 dm3 kg−1); pre-treatment did not enhance CH4 yields for C. vulgaris, but for A. obliquus (ultrasonication +20%). Pre-treatment was more effective for cooled than freeze-thawed microalgal biomass and combined effects acted strain dependently.This work was performed in the frame of the Austrian COMET program under grant number 834018. It has received funding from the Republic of Austria and the Federal Provinces of Styria, Lower Austria and Burgenland. Co-funding from the industry partner Erber Group shall be highly acknowledged

CLEC-2 expression is maintained on activated platelets and on platelet microparticles

The C-type lectin-like receptor CLEC-2 mediates platelet activation through a hem-immunoreceptor tyrosine-based activation motif (hemITAM). CLEC-2 initiates a Src- and Syk-dependent signaling cascade that is closely related to that of the 2 platelet ITAM receptors: glycoprotein (GP)VI and FcγRIIa. Activation of either of the ITAM receptors induces shedding of GPVI and proteolysis of the ITAM domain in FcγRIIa. In the present study, we generated monoclonal antibodies against human CLEC-2 and used these to measure CLEC-2 expression on resting and stimulated platelets and on other hematopoietic cells. We show that CLEC-2 is restricted to platelets with an average copy number of ∼2000 per cell and that activation of CLEC-2 induces proteolytic cleavage of GPVI and FcγRIIa but not of itself. We further show that CLEC-2 and GPVI are expressed on CD41+ microparticles in megakaryocyte cultures and in platelet-rich plasma, which are predominantly derived from megakaryocytes in healthy donors, whereas microparticles derived from activated platelets only express CLEC-2. Patients with rheumatoid arthritis, an inflammatory disease associated with increased microparticle production, had raised plasma levels of microparticles that expressed CLEC-2 but not GPVI. Thus, CLEC-2, unlike platelet ITAM receptors, is not regulated by proteolysis and can be used to monitor platelet-derived microparticles

Phenotypic spectrum and prevalence of INPP5E mutations in Joubert Syndrome and related disorders

<p>Joubert syndrome and related disorders (JSRD) are clinically and genetically heterogeneous ciliopathies sharing a peculiar midbrain-hindbrain malformation known as the 'molar tooth sign'. To date, 19 causative genes have been identified, all coding for proteins of the primary cilium. There is clinical and genetic overlap with other ciliopathies, in particular with Meckel syndrome (MKS), that is allelic to JSRD at nine distinct loci. We previously identified the INPP5E gene as causative of JSRD in seven families linked to the JBTS1 locus, yet the phenotypic spectrum and prevalence of INPP5E mutations in JSRD and MKS remain largely unknown. To address this issue, we performed INPP5E mutation analysis in 483 probands, including 408 JSRD patients representative of all clinical subgroups and 75 MKS fetuses. We identified 12 different mutations in 17 probands from 11 JSRD families, with an overall 2.7% mutation frequency among JSRD. The most common clinical presentation among mutated families (7/11, 64%) was Joubert syndrome with ocular involvement (either progressive retinopathy and/or colobomas), while the remaining cases had pure JS. Kidney, liver and skeletal involvement were not observed. None of the MKS fetuses carried INPP5E mutations, indicating that the two ciliopathies are not allelic at this locus.</p>