36 research outputs found
Green gravel as a vector of dispersal for kelp restoration
Kelp forests are experiencing substantial declines due to climate change, particularly ocean warming and marine heatwaves, and active interventions are necessary to halt this decline. A new restoration approach termed “green gravel” has shown promise as a tool to combat kelp forest loss. In this approach, substrata (i.e. small gravel) are seeded with kelp propagules, reared in controlled conditions in the laboratory before out-planting to degraded reefs. Here, we tested the feasibility of cultivating Australia’s dominant kelp, Ecklonia radiata on green gravel with the aim of optimising the seeding conditions for E.radiata. We seeded substrata (i.e. gravel), that had different surface texture and size, with E. radiata gametophytes at two average seeding densities: high density of ~230 fragments mL-1 and low density of ~115 fragments mL-1. The tested substrata were small basalt, large basalt, crushed laterite and limestone. Gametophytes successfully adhered to all four tested substrata, however, gametophytes that adhered to the limestone gravel (the natural reef type off Western Australia) suffered extreme tissue bleaching likely due to dissolution and decrease in seawater pH. Gametophytes that adhered to the three other test substrata were healthy, fertilised following seeding and microscopic sporophytes were observed attaching to the gravel. Substrata and seeding density did not affect sporophyte growth (i.e. length) at the time of transferring into aquarium tanks (after three months of rearing in incubators) but over time substrata showed a significant effect on maximum lengths. After 12 months in aquarium tanks, sporophytes on both small and large basalt gravel were significantly larger than those on the crushed laterite. Gametophytes were also found to not only survive on the gravel itself but also detach from the gravel, settle successfully, fertilise and develop into healthy sporophytes ex situ on the surrounding substratum through lateral transfer. Substrata had a significant effect on density of detached gametophytes with rougher and larger gravel showing higher densities of detachment. Our results show the potential for green gravel to be a vector of dispersal for restoration in Western Australia where natural recovery of kelp forests has failed.publishedVersio
How Damage Diversification Can Reduce Systemic Risk
We consider the problem of risk diversification in complex networks. Nodes
represent e.g. financial actors, whereas weighted links represent e.g.
financial obligations (credits/debts). Each node has a risk to fail because of
losses resulting from defaulting neighbors, which may lead to large failure
cascades. Classical risk diversification strategies usually neglect network
effects and therefore suggest that risk can be reduced if possible losses
(i.e., exposures) are split among many neighbors (exposure diversification,
ED). But from a complex networks perspective diversification implies higher
connectivity of the system as a whole which can also lead to increasing failure
risk of a node. To cope with this, we propose a different strategy (damage
diversification, DD), i.e. the diversification of losses that are imposed on
neighboring nodes as opposed to losses incurred by the node itself. Here, we
quantify the potential of DD to reduce systemic risk in comparison to ED. For
this, we develop a branching process approximation that we generalize to
weighted networks with (almost) arbitrary degree and weight distributions. This
allows us to identify systemically relevant nodes in a network even if their
directed weights differ strongly. On the macro level, we provide an analytical
expression for the average cascade size, to quantify systemic risk.
Furthermore, on the meso level we calculate failure probabilities of nodes
conditional on their system relevance
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An Effective CTL Peptide Vaccine for Ebola Zaire Based on Survivors’ CD8+ Targeting of a Particular Nucleocapsid Protein Epitope with Potential Implications for COVID-19 Vaccine Design
The 2013-2016 West Africa EBOV epidemic was the biggest EBOV outbreak to date. An analysis of virus-specific CD8+ T-cell immunity in 30 survivors showed that 26 of those individuals had a CD8+ response to at least one EBOV protein. The dominant response (25/26 subjects) was specific to the EBOV nucleocapsid protein (NP). It has been suggested that epitopes on the EBOV NP could form an important part of an effective T-cell vaccine for Ebola Zaire. We show that a 9-amino-acid peptide NP44-52 (YQVNNLEEI) located in a conserved region of EBOV NP provides protection against morbidity and mortality after mouse adapted EBOV challenge. A single vaccination in a C57BL/6 mouse using an adjuvanted microsphere peptide vaccine formulation containing NP44-52 is enough to confer immunity in mice. Our work suggests that a peptide vaccine based on CD8+ T-cell immunity in EBOV survivors is conceptually sound and feasible. Nucleocapsid proteins within SARS-CoV-2 contain multiple class I epitopes with predicted HLA restrictions consistent with broad populatio
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Green gravel as a vector of dispersal for kelp restoration
Kelp forests are experiencing substantial declines due to climate change, particularly ocean warming and marine heatwaves, and active interventions are necessary to halt this decline. A new restoration approach termed “green gravel” has shown promise as a tool to combat kelp forest loss. In this approach, substrata (i.e. small gravel) are seeded with kelp propagules, reared in controlled conditions in the laboratory before out-planting to degraded reefs. Here, we tested the feasibility of cultivating Australia’s dominant kelp, Ecklonia radiata on green gravel with the aim of optimising the seeding conditions for E.radiata. We seeded substrata (i.e. gravel), that had different surface texture and size, with E. radiata gametophytes at two average seeding densities: high density of ~230 fragments mL-1 and low density of ~115 fragments mL-1. The tested substrata were small basalt, large basalt, crushed laterite and limestone. Gametophytes successfully adhered to all four tested substrata, however, gametophytes that adhered to the limestone gravel (the natural reef type off Western Australia) suffered extreme tissue bleaching likely due to dissolution and decrease in seawater pH. Gametophytes that adhered to the three other test substrata were healthy, fertilised following seeding and microscopic sporophytes were observed attaching to the gravel. Substrata and seeding density did not affect sporophyte growth (i.e. length) at the time of transferring into aquarium tanks (after three months of rearing in incubators) but over time substrata showed a significant effect on maximum lengths. After 12 months in aquarium tanks, sporophytes on both small and large basalt gravel were significantly larger than those on the crushed laterite. Gametophytes were also found to not only survive on the gravel itself but also detach from the gravel, settle successfully, fertilise and develop into healthy sporophytes ex situ on the surrounding substratum through lateral transfer. Substrata had a significant effect on density of detached gametophytes with rougher and larger gravel showing higher densities of detachment. Our results show the potential for green gravel to be a vector of dispersal for restoration in Western Australia where natural recovery of kelp forests has failed