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2 Posts tagged with the polychaeta tag
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An interdisciplinary team of Museum mineralogists and zoologists,  with external collaborators, have been looking at the impacts of nano  particles on the environment for some years.  Silver nanoparticles  (AgNPs) are widely used in industry for manufactured goods and this may result in environmental impacts, notably within aquatic ecosystems. Silver can be toxic to living organisms when they are exposed to it by selected routes and in particular forms.  It's important that in pursuing the positive benefits of NPs, we are able to understand and avoid the negative impacts.

 

Scientists have over many years developed understanding of which substances are toxic, and why.  Sometimes this knowledge will have come about as a result of seeing the effects of unintended exposure to humans in factories or accidentally contaminated food. Exposure to toxic substances can result in death or very serious health effects to humans or other organisms.  However, we have a lot to learn - much of our understanding has arisen from particular cases or studies and one area of particular complexity is exposure through the environment.

 

We are exposed to a whole range of chemical substances in our environment, often at very low levels of concentration and sometimes over many years.  The same is true of other organisms - although the effects of particular substances will be different for different species, as a result of their different genetic makeup, diet, habitat and other factors.  Further, exposure to different combinations of chemical substances can lead to the toxic effect of a particular substance being decreased or increased in a particular and often unexpected way.

 

The use of nanoparticles has increased tremendously in recent years in industry.  Nanoparticles are very tiny particles of a substance - less than 100 nanometres in all three dimensions (one nanometre is one billionth of a metre).  This size means that they can have different chemical, physical and biological properties from larger particles, and this includes their toxic effects.

 

The study looked at estuaries, which are complex environments and often the site of human industrial developments.  Sediments in estuaries are sinks for numerous pollutants, but also habitat and food for deposit feeders (eating the sediments) such as the polychaete worm Nereis diversicolor.

 

Ingested sediments were investigated as an important route of uptake for NPs. The Museum scientists looked at N. diversicolor that had eaten sediment contaminated with either citrate-capped AgNPs (30 +/- 5 nm) or aqueous silver for 10 days. The experimental results indicate separate routes for silver to enter the cells of the worms and differing final locations of Ag delivered in dissolved and NP form.

 

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For AgNPs an endocytotic pathway appears to be a key route of cellular uptake - endocytosis means that the NPs are ingested by the cells of the organism, engulfing the NPs into a vacuole within the cell, in contrast to the usual cross-membrane transport of dissolved substances.

 

All these findings lead to a better understanding of how organisms respond, interact and deal with NPs - this is complex and will have a substantial influence on toxic effects and environmental impact.


GARCIA-ALONSO J, KHAN F R, MISRA S K, Turmaine M, SMITH B D, RAINBOW P S, LUOMA S N, VALSAMI-JONES E 2011. Cellular internalization of silver nanoparticles in gut epithelia of the Estuarine Polychaete Nereis diversicolor. Environmental Science and Technology 45: 4630-4636.

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Adrian Glover (Zoology) and Helena Wiklund have also been awarded a Marie Curie Intra-European Fellowship for Helena to work on deep sea biology.  This Marie Curie scheme, funded by the European Union, allows experienced EU researchers to work in other EU countries to develop skills and collaboration, producing high-quality science.  The NHM bids successfully for funds to a wide range of research funding agencies each year in the UK and elsewhere.

 

They will be working on worms in the deep sea: the last unexplored frontier on Earth, where in recent years many hundreds of new species have been discovered. We are familar with shallow coastal seas affected by tidal currents, richly productive and fertile.  In contrast, the deep sea has many areas where nutrients are scarce, cold and subject to high pressure, deep ocean basins over 4 kilometres below the surface.  The lives of organisms in the deep sea are often very different from those of related species near the surface.

 

A key question in deep-sea biology is that of whether and how deep-sea animals are able to disperse. Many organisms, such as worms, have limited abilty to move over any distance as adults: some have planktonic young that can be carried over distance by currents.

 

The dominant idea for the deep sea has been one of cosmopolitanism: that animals are relatively mobile at certain stages of their lfe cycle and have easy access to all ocean basins around the world. However, this has been recently challenged and for many species there may be barriers to dispersal in the form of substrate specialisation (the requirement to live in particular types of sediment) limited mobility or particular reproductive characteristics.

 

This study will target one of the most abundant and species-rich groups, the polychaetes. To answer questions of dispersal and evolution in the deep sea Helena will study three contrasting groups of polychaetes:one group with mobile planktonic larvae; a second group with direct-developing larvae, similar in form to the adults; and a third group, the newly discovered genus of ’bone-eating’ worms, Osedax, that are sessile (non-mobile) and exist on the most specialised of habitats – whale bones on the sea floor. (One of which, Osedax mucofloris, was a NHM species of the day in 2010)

 

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Osedax mucofloris


The study will use molecular data (such as from DNA analysis) from material from several ocean basins to construct phylogenies (evolutionary trees) to evaluate the relationships within the three groups.  It will have great value in understanding species formation, population connections and the processes that drive biodiversity in the deep sea.