61 research outputs found
Are current estimates of coral reef biodiversity too low? The view through the window of a microcosm
Mesophyllum sphaericum sp. nov. (Corallinales, Rhodophyta): a new maërl-forming species from the northeast Atlantic
Mesophyllum sphaericum sp. nov. is described based
on spherical mae¨rl individuals (up to 10 cm) collected in a shallow subtidal mae¨rl bed in Galicia
(NW Spain). The thalli of these specimens are
radially organized, composed of arching tiers of
compact medullary filaments. Epithallial cells have
flattened to rounded outermost walls, and they occur
in a single layer. Subepithallial initials are as long as,
or longer than the daughter cells that subtend them.
Cell fusions are abundant. Multiporate asexual conceptacles are protruding, mound-like with a flattened
pore plate, lacking a peripheral raised rim. Filaments lining the pore canal and the conceptacle roof
are composed of five to six cells with straight elongate and narrow cells at their base. Carposporangial
conceptacles are uniporate, protruding, and conical.
Spermatangial conceptacles were not observed.
Molecular results placed M. sphaericum near to
M. erubescens, but M. sphaericum is anatomically close
to M. canariense. The examination of the holotype
and herbarium specimens of M. canariense indicated
that both species have pore canal filaments with elongate basal cells, but they differ in number of
cells (five to six in M. sphaericum vs. four in
M. canariense). Based on the character of pore canal
filaments, M. canariense shows similarities with
M. erubescens (three to five celled). The outermost
walls of epithallial cells of M. canariense are flared
compared to the round to flattened ones of M. erubescens, the latter being widely accepted for the genus
Mesophyllum. The addition of M. sphaericum as new
mae¨rl-forming species suggests that European mae¨rl
beds are more biodiverse than previously understood
Dissipation and spontaneous symmetry breaking in brain dynamics
We compare the predictions of the dissipative quantum model of brain with
neurophysiological data collected from electroencephalograms resulting from
high-density arrays fixed on the surfaces of primary sensory and limbic areas
of trained rabbits and cats. Functional brain imaging in relation to behavior
reveals the formation of coherent domains of synchronized neuronal oscillatory
activity and phase transitions predicted by the dissipative model.Comment: Restyled, slight changes in title and abstract, updated bibliography,
J. Phys. A: Math. Theor. Vol. 41 (2008) in prin
The genus phymatolithon in the Gulf of Maine
New information on anatomy, cytology and the development of reproductive structures is presented to show that Phymatolithon is a genus distinct from both Clathromorphum and the branching members of Lithothamnium . Also, a new species of Phymatolithon , Ph. rugulosum , is described. The reproductive cycles and geographic and bathymetric distributions of Ph. laevigatum and Ph. rugulosum in the Gulf of Maine are presented and discussed. There is strong indication that the geographic distribution of crustose corallines in the region is controlled primarily by maximum summer temperatures. The depth distributions are apparently controlled primarily by decrease of light with depth, though temperatures and substrate are also factors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42883/1/10750_2004_Article_BF00170412.pd
The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance
INTRODUCTION
Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic.
RATIONALE
We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs).
RESULTS
Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants.
CONCLUSION
Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century
Growth of corallinaceae on the coast of Maine : final report
http://deepblue.lib.umich.edu/bitstream/2027.42/3174/5/baa9982.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/3174/4/baa9982.0001.001.tx
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