Background
The coronavirus disease 2019 (COVID-19) global pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began in late 2019. Researchers around the world ...are aggressively working to develop a vaccine. One of the vaccines approved against COVID-19 is Oxford–AstraZeneca chimpanzee adenovirus vectored vaccine ChAdOx1 nCoV-19.
Case report
We described a patient who developed four limb distal paraesthesia, postural instability, and facial diplegia, ten days after vaccination with ChAdOx1 nCoV-19 (ABW1277). The electrophysiological findings were compatible with acute demyelinating motor polyneuropathy (Guillain-Barrè syndrome).
Discussion
We therefore want to describe a temporal correlation between administration of ChAdOx1 nCoV-19 (ABW1277) vaccine and GBS without evidence of other predisposing infectious or autoimmune factors. This paper aims to highlight the importance of pharmacovigilance and subsequent reports will be needed to evaluate the possible correlation between these two events.
Diatom microalgae have great industrial potential as next-generation sources of biomaterials and biofuels. Effective scale-up of their production can be pursued by enhancing the efficiency of their ...photosynthetic process in a way that increases the solar-to-biomass conversion yield. A proof-of-concept demonstration is given of the possibility of enhancing the light absorption of algae and of increasing their efficiency in photosynthesis by in vivo incorporation of an organic dye which acts as an antenna and enhances cells' growth and biomass production without resorting to genetic modification. A molecular dye (Cy5) is incorporated in Thalassiosira weissflogii diatom cells by simply adding it to the culture medium and thus filling the orange gap that limits their absorption of sunlight. Cy5 enhances diatoms' photosynthetic oxygen production and cell density by 49% and 40%, respectively. Cy5 incorporation also increases by 12% the algal lipid free fatty acid (FFA) production versus the pristine cell culture, thus representing a suitable way to enhance biofuel generation from algal species. Time-resolved spectroscopy reveals Förster Resonance Energy Transfer (FRET) from Cy5 to algal chlorophyll. The present approach lays the basis for non-genetic tailoring of diatoms' spectral response to light harvesting, opening up new ways for their industrial valorization.
Key message
Gene silencing of
BcDCL
genes improves gray mold disease control in the cultivated strawberry.
Gene silencing technology offers new opportunities to develop new formulations or new ...pathogen-resistant plants for reducing impacts of agricultural systems. Recent studies offered the proof of concept that the symptoms of gray mold can be reduced by downregulating
Dicer-like 1
(
DCL1
) and
2
(
DCL2
) genes of
Botrytis cinerea
. In this study, we demonstrate that both solutions based on dsRNA topical treatment and
in planta
expression targeting
BcDCL1
and
BcDCL2
genes can be used to control the strawberry gray mold, the most harmful disease for different fruit crops. 50, 70 and 100 ng μL
−1
of naked
BcDCL1/2
dsRNA, sprayed on plants of
Fragaria
x
ananassa
cultivar Romina in the greenhouse, displayed significant reduction of susceptibility, compared to the negative controls, but to a lesser extent than the chemical fungicide. Three independent lines of Romina cultivar were confirmed for their stable expression of the hairpin gene construct that targets the
Bc-DCL1
and
2
sequences (hp-Bc-DCL1/2), and for the production of hp construct-derived siRNAs, by qRT-PCR and Northern blot analyses. In vitro and in vivo detached leaves, and fruits from the hp-Bc-DCL1/2 lines showed significantly enhanced tolerance to this fungal pathogen compared to the control. This decreased susceptibility was correlated to the reduced fungal biomass and the downregulation of the
Bc-DCL1
and
2
genes in
B. cinerea
. These results confirm the potential of both RNAi-based products and plants for protecting the cultivated strawberry from
B. cinerea
infection, reducing the impact of chemical pesticides on the environment and the health of consumers.
Astaxanthin is a ketocarotenoid with high antioxidant power used in different fields as healthcare, food/feed supplementation and as pigmenting agent in aquaculture. Primary producers of astaxanthin ...are some species of microalgae, unicellular photosynthetic organisms, as Haematococcus lacustris. Astaxanthin production by cultivation of Haematococcus lacustris is costly due to low biomass productivity, high risk of contamination and the requirement of downstream extraction processes, causing an extremely high price on the market. Some microalgae species are also primary producers of omega-3 fatty acids, essential nutrients for humans, being related to cardiovascular wellness, and required for visual and cognitive development. One of the main well-known producers of omega-3 fatty eicosapentaenoic acid (EPA) is the marine microalga Nannochloropsis gaditana (named also Microchloropsis gaditana): this species has been already approved by the Food and Drug Administration (FDA) for human consumption and it is characterized by a fast grow phenotype. Here we obtained by chemical mutagenesis a Nannochloropsis gaditana mutant strain, called S4, characterized by increased carotenoid to chlorophyll ratio. S4 strain showed improved photosynthetic activity, increased lipid productivity and increased ketocarotenoids accumulation, producing not only canthaxanthin but also astaxanthin, usually found only in traces in the WT strain. Ketocarotenoids produced in S4 strain were extractible in different organic solvents, with the highest efficiency observed upon microwaves pre-treatment followed by methanol extraction. By cultivation of S4 strain at different irradiances it was possible to produce up to 1.3 and 5.2 mgL.sup.-1 day.sup.-1 of ketocarotenoids and EPA respectively, in a single cultivation phase, even in absence of stressing conditions. Genome sequencing of S4 strain allowed to identify 199 single nucleotide polymorphisms (SNP): among the mutated genes, mutations in a carotenoid oxygenase gene and in a glutamate synthase gene could explain the different carotenoids content and the lower chlorophylls content, respectively. By chemical mutagenesis and selection of strain with increased carotenoids to chlorophyll ratio it was possible to isolate a new Nannochloropsis gaditana strain, called S4 strain, characterized by increased lipids and ketocarotenoids accumulation. S4 strain can thus be considered as novel platform for ketocarotenoids and EPA production for different industrial applications.
is a photosynthetic unicellular microalgae considered one of the most interesting marine algae to produce biofuels and food additive due to its rapid growth rate and high lipid accumulation. Although ...microalgae are attractive platforms for solar energy bioconversion, the overall efficiency of photosynthesis is reduced due to the steep light gradient in photobioreactors. Moreover, accumulation of lipids in microalgae for biofuels production is usually induced in a two-phase cultivation process by nutrient starvation, with additional time and costs associated. In this work, a biotechnological approach was directed for the isolation of strains with improved light penetration in photobioreactor combined with increased lipids productivity.
Mutants of
were obtained by chemical mutagenesis and screened for having both a reduced chlorophyll content per cell and increased affinity for Nile red, a fluorescent dye which binds to cellular lipid fraction. Accordingly, one mutant, called
, was selected and characterized for having a 30% reduction of chlorophyll content per cell and an almost 80% increase of lipid productivity compared to WT in nutrient-replete conditions, with C16:0 and C18:0 fatty acids being more than doubled in the mutant. Whole-genome sequencing revealed mutations in 234 genes in
mutant among which there is a non-conservative mutation in the
synthase gene. This gene encodes for an enzyme involved in the biosynthesis of DGDG, one of the major lipids found in the thylakoid membrane and it is thus involved in chloroplast biogenesis. Lipid biosynthesis is strongly influenced by light availability in several microalgae species, including
: reduced chlorophyll content per cell and more homogenous irradiance in photobioreactor is at the base for the increased lipid productivity observed in the
mutant.
The results herein obtained presents a promising strategy to produce algal biomass enriched in lipid fraction to be used for biofuel and biodiesel production in a single cultivation process, without the additional complexity of the nutrient starvation phase. Genome sequencing and identification of the mutations introduced in
mutant suggest possible genes responsible for the observed phenotypes, identifying putative target for future complementation and biotechnological application.
We explored the action of chronic valproic acid (VPA) on the human epileptic cortex by means of transcranial magnetic stimulation (TMS). TMS is an emerging biomarker for neurotropic drugs. We had 15 ...drug-naive patients with different epileptic syndromes. Interictally, we measured several TMS indexes of cortical excitability before commencing VPA and 3 months later. At that time, all patients were clinical responders to the drug, whose plasma levels were in the “therapeutic range”. We then compared the two conditions, while 18 healthy subjects, of whom 12 were retested at a similar delay, acted as controls. In the pooled patients, the baseline resting motor threshold to TMS was similar to that of controls, but it increased significantly (
P < 0.05) after VPA. Intracortical facilitation, another index of cortical excitability, was abnormally enhanced at baseline but decreased significantly after VPA (
P < 0.05). On splitting patients according to their diagnosis, the threshold increase was significant (
P < 0.05) among partial, but not generalized epilepsies. The reverse was true for changes in intracortical facilitation. TMS phenomena had no linear relation to VPA serum levels. Based on the known pharmacology of TMS effects, VPA reduced the intrinsic membrane excitability of motor cortical neurons, possibly through changes in Na+ channel activity. Then, VPA corrected a transmitter-mediated interneuronal hyper-excitability of the primary motor cortex. The former effect was best seen in partial, and the latter in generalized epilepsy patients.
In photosynthetic eukaryotes, the metabolite exchange between chloroplast and mitochondria ensures efficient photosynthesis under saturating light conditions. The Chlamydomonas reinhardtii mutant ...stm6 is devoid of the mitochondrial transcription termination factor MOC1 and aberrantly expresses the mitochondrial genome, resulting in enhanced photosynthetic hydrogen production and diminished light tolerance. We analyzed the modulation of mitochondrial and chlororespiration during the acclimation of stm6 and the MOC1-complemented strain to excess light. Although light stress stimulated mitochondrial respiration via the energy-conserving cytochrome c pathway in both strains, the mutant was unable to fine-tune the expression and activity of oxidative phosphorylation complex I in excess light, which was accompanied by an increased mitochondrial respiration via the alternative oxidase pathway. Furthermore, stm6 failed to fully activate chlororespiration and cyclic electron flow due to a more oxidized state of the chloroplast stroma, which is caused by an increased mitochondrial electron sink capacity. Increased susceptibility to photoinhibition of PSII in stm6 demonstrates that the MOC1-dependent modulation of mitochondrial respiration helps control the stromal redox poise as a crucial part of high-light acclimation in C. reinhardtii.
Summary
Chlorella vulgaris is a fast‐growing fresh‐water microalga cultivated on the industrial scale for applications ranging from food to biofuel production. To advance our understanding of its ...biology and to establish genetics tools for biotechnological manipulation, we sequenced the nuclear and organelle genomes of Chlorella vulgaris 211/11P by combining next generation sequencing and optical mapping of isolated DNA molecules. This hybrid approach allowed us to assemble the nuclear genome in 14 pseudo‐molecules with an N50 of 2.8 Mb and 98.9% of scaffolded genome. The integration of RNA‐seq data obtained at two different irradiances of growth (high light, HL versus low light, LL) enabled us to identify 10 724 nuclear genes, coding for 11 082 transcripts. Moreover, 121 and 48 genes, respectively, were found in the chloroplast and mitochondrial genome. Functional annotation and expression analysis of nuclear, chloroplast and mitochondrial genome sequences revealed particular features of Chlorella vulgaris. Evidence of horizontal gene transfers from chloroplast to mitochondrial genome was observed. Furthermore, comparative transcriptomic analyses of LL versus HL provided insights into the molecular basis for metabolic rearrangement under HL versus LL conditions leading to enhanced de novo fatty acid biosynthesis and triacylglycerol accumulation. The occurrence of a cytosolic fatty acid biosynthetic pathway could be predicted and its upregulation upon HL exposure was observed, consistent with the increased lipid amount under HL conditions. These data provide a rich genetic resource for future genome editing studies, and potential targets for biotechnological manipulation of Chlorella vulgaris or other microalgae species to improve biomass and lipid productivity.
Significance Statement
Microalgae cultivation is one of the most promising strategies for novel food or biofuel production. High‐quality genome information is required for understanding algae biology, for their biotechnological optimization and for genome editing applications. Here, the genome of Chlorella vulgaris, one of the green algae species with the highest productivity potential, is presented and functionally annotated, revealing notable features among Chlorophyta.
Microalgae represent a potential solution to reduce CO2 emission exploiting their photosynthetic activity. Here, the physiologic and metabolic responses at the base of CO2 assimilation were ...investigated in conditions of high or low CO2 availability in two of the most promising algae species for industrial cultivation, Chlorella sorokiniana and Chlorella vulgaris. In both species, high CO2 availability increased biomass accumulation with specific increase of triacylglycerols in C. vulgaris and polar lipids and proteins in C. sorokiniana. Moreover, high CO2 availability caused only in C. vulgaris a reduced NAD(P)H/NADP+ ratio and reduced mitochondrial respiration, suggesting a CO2 dependent increase of reducing power consumption in the chloroplast, which in turn influences the redox state of the mitochondria. Several rearrangements of the photosynthetic machinery were observed in both species, differing from those described for the model organism Chlamydomonas reinhardtii, where adaptation to carbon availability is mainly controlled by the translational repressor NAB1. NAB1 homologous protein could be identified only in C. vulgaris but lacked the regulation mechanisms previously described in C. reinhardtii. Acclimation strategies to cope with a fluctuating inorganic carbon supply are thus diverse among green microalgae, and these results suggest new biotechnological strategies to boost CO2 fixation.
High/low CO2 availability induces in Chlorella vulgaris and Chlorella sorokiniana specific cell responses as lipids remodelling, modulation of mitochondrial respiration and adaptations of the photosynthetic apparatus.
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