55 research outputs found
Infectious Offspring: How Birds Acquire and Transmit an Avian Polyomavirus in the Wild
Detailed patterns of primary virus acquisition and subsequent dispersal in wild vertebrate populations are virtually absent. We show that nestlings of a songbird acquire polyomavirus infections from larval blowflies, common nest ectoparasites of cavity-nesting birds, while breeding adults acquire and renew the same viral infections via cloacal shedding from their offspring. Infections by these DNA viruses, known potential pathogens producing disease in some bird species, therefore follow an ‘upwards vertical’ route of an environmental nature mimicking horizontal transmission within families, as evidenced by patterns of viral infection in adults and young of experimental, cross-fostered offspring. This previously undescribed route of viral transmission from ectoparasites to offspring to parent hosts may be a common mechanism of virus dispersal in many taxa that display parental care
Marine fish traits follow fast-slow continuum across oceans
A fundamental challenge in ecology is to understand why species are found where they are and predict
where they are likely to occur in the future. Trait-based approaches may provide such understanding,
because it is the traits and adaptations of species that determine which environments they can inhabit.
It is therefore important to identify key traits that determine species distributions and investigate
how these traits relate to the environment. Based on scientific bottom-trawl surveys of marine fish
abundances and traits of >1,200 species, we investigate trait-environment relationships and project
the trait composition of marine fish communities across the continental shelf seas of the Northern
hemisphere. We show that traits related to growth, maturation and lifespan respond most strongly to
the environment. This is reflected by a pronounced “fast-slow continuum” of fish life-histories, revealing
that traits vary with temperature at large spatial scales, but also with depth and seasonality at more
local scales. Our findings provide insight into the structure of marine fish communities and suggest that
global warming will favour an expansion of fast-living species. Knowledge of the global and local drivers
of trait distributions can thus be used to predict future responses of fish communities to environmental
change.Postprint2,92
SMF-1, SMF-2 and SMF-3 DMT1 Orthologues Regulate and Are Regulated Differentially by Manganese Levels in C. elegans
Manganese (Mn) is an essential metal that can exert toxic effects at high concentrations, eventually leading to Parkinsonism. A major transporter of Mn in mammals is the divalent-metal transporter (DMT1). We characterize here DMT1-like proteins in the nematode C. elegans, which regulate and are regulated by Mn and iron (Fe) content. We identified three new DMT1-like genes in C. elegans: smf-1, smf-2 and smf-3. All three can functionally substitute for loss of their yeast orthologues in S. cerevisiae. In the worm, deletion of smf-1 or smf-3 led to an increased Mn tolerance, while loss of smf-2 led to increased Mn sensitivity. smf mRNA levels measured by QRT-PCR were up-regulated upon low Mn and down-regulated upon high Mn exposures. Translational GFP-fusions revealed that SMF-1 and SMF-3 strongly localize to partially overlapping apical regions of the gut epithelium, suggesting a differential role for SMF-1 and SMF-3 in Mn nutritional intake. Conversely, SMF-2 was detected in the marginal pharyngeal epithelium, possibly involved in metal-sensing. Analysis of metal content upon Mn exposure in smf mutants revealed that SMF-3 is required for normal Mn uptake, while smf-1 was dispensable. Higher smf-2 mRNA levels correlated with higher Fe content, supporting a role for SMF-2 in Fe uptake. In smf-1 and smf-3 but not in smf-2 mutants, increased Mn exposure led to decreased Fe levels, suggesting that both metals compete for transport by SMF-2. Finally, SMF-3 was post-translationally and reversibly down-regulated following Mn-exposure. In sum, we unraveled a complex interplay of transcriptional and post-translational regulations of 3 DMT1-like transporters in two adjacent tissues, which regulate metal-content in C. elegans
Low birth weight and the global burden of kidney disease
Low birth weight (LBW) and intrauterine growth restriction are major contributors to the global burden of non-communicable diseases. A Norwegian registry study has confirmed that LBW is associated with an increased risk of developing end-stage renal disease by 40 years of age, which could not be explained by familial factors
A role for antigen in the maintenance of immunological memory
The immune system has a memory that it
exhibits in the enhanced and augmented
responses the second time it meets an
antigen. The memory is the result of a
number of changes to the system brought
about during the primary response. The
most important of these changes is the
formation of an expanded pool of antigenspecific
memory cells. One of the
enduring questions in immunology is how
these memory cells are maintained for
such long periods.
Until about 10 years ago, memory cells were
thought to be very long-lived cells that
required little, if any, external input to keep
them alive. This view arose not out of data
showing long cellular lifespans, but from the
observation that memory responses could be
elicited many years after immunization or
infection. It has been a common failure in
thinking about immunological memory to
imbue the individual cells with properties of
the whole system. Around 10–12 years ago, a
number of studies were published that highlighted
the influence of antigen on the survival
of memory cells. These studies indicated
that although the antigen-specific clones were
long-lived, the constituent memory cells were
relatively short-lived and required continued
antigenic stimulation (1–3). In the intervening period, the argument about antigen dependence
has continued, and recent experiments
have swung opinion back towards an antigenindependent
view. In this article, I wish to
argue that in reality, as opposed to experimental
models, the role of antigen in memory
maintenance is a very important one, and that
antigen persistence might be a crucial asset
for any vaccine
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