The BBC has this report on an interesting marine biology discovery, relevant to explaining trace fossils.  Unfortunately it's a bit vague (exemplified by its title - 'Grape' is key to fossil puzzle), and doesn't have a link to the original research paper in Current Biology. Personally, I think it looks less like a grape and more like a truffle.  The picture to the left shows a cleaned up example - the real things roll around the sea floor covered in mud.

Greg Laden's Blog - Giant Gromia (amoebas) may account for ancient sea floor tracks presents a rather more coherent account of the paper, and includes a citation.  Unfortunately my university doesn't have an online subscription to Current Biology.  Rats! Rats!

A pair of recent issues of Science plonked into my mail box this week.  Among the items that caught my eyes was an exciting brief communication in Science shows a rare example of what appears to be fossil evidence of behaviour. These are Waptia-like arthropods from the Lower Cambrian, which appear to have been preserved while engaged in some form of processionary behaviour. Unlike known present day processionary arthropods, these chains of individuals appear to be physically linked - you can see in the figure that there is overlap between an individual's carapace and the preceding individual's telson. The authors propose the chains reflect migratory behaviour rather than feeding or reproduction.

Perhaps I have just taken the wrong career path in science, but I do find the reports of interesting new fossils rather exciting.  And how could I resist a paper describing a "bizarre Jurassic maniraptoran"?  It seems that hardly a week goes by without a striking fossil from China being described.  This one hit the BBC news pages, from where I linked the reconstruction of the animal below.

This week's edition of Nature has a brief paper (doi:10.1038/nature07390) reporting on the identification of an HIV positive tissue sample collected in Leopoldville (now Kinshasa) in what was then the Belgian Congo, and now known as the Democratic Republic of the Congo.  Sequence data derived from the tissue was used to investigate the chronology of the appearance of HIV from its likely simian origin.

This is a piece of research which hit the news services (see for example this page at the BBC news website).  The research has a number of features which earmark it for media interest: an important virus, a serious disease with a global spread, and a simple take-home message as to the origin of the virus.  This raised my interest and I looked at the paper.  Incidentally, the paper raises issues to do with complexity of statistical analysis: I imagine many readers such as I, and the journos who wrote articles in the press, have little or no chance of understanding what an "unconstrained Bayesian Markov chain Monte Carlo method" is, and are similarly limited in one's real critical analysis of conclusions reached by that means!  I am forced to assume that all is above board in the statistical and computational aspects of this paper, and that the referees have done their job!  In addition, it's always interesting in studies of ancient DNA (and cases where sample preservation was not originally intended to preserve nucleic acids) to know what measures were taken to ensure that contamination with modern DNA did not happen.

I was intrigued by a brief news piece in the latest issue of Science to fall onto my desk (the 22nd August issue).  This concerns the recently published genome sequence of Trichoplax adhaerens, a peculiar animal in a phylum I'd never heard of.  That in itself was interesting, particularly as placozoans have a really odd body plan that involves a mere four cell types.  Wikipedia has a nice description of Placozoa, from which the image below comes.

On browsing the web a bit further, I found this movie (Quicktime format) of a placozoan moving.  I presume this would be Trichoplax adhaerens, as this is the only known species in the phylum - a second described species, T. reptans, was apparently described at the end of the 19th century but hasn't ben seen again and it's existence is doubtful.

A. Bhutkar, S. W. Schaeffer, S. M. Russo, M. Xu, T. F. Smith, W. M. Gelbart (2008). Chromosomal Rearrangement Inferred From Comparisons of 12 Drosophila Genomes Genetics, 179 (3), 1657-1680 DOI: 10.1534/genetics.107.086108

Back when I was a carefree postdoc, one of the projects I worked on was the assembly of a molecular physical map of the Drosophila melanogaster genome. Of course, Drosophila researchers had for years been using a physical map, the polytene chromosome map, and indeed we used this as the framework on which we assembled our molecular map using cosmid clones. These papers take the genome sequences of 11 Drosophila species (plus the sequence of Drosophila melanogaster, determined back in 2000), fit them to the polytene chromosome maps, and examine chromosome rearrangments seen in inter-species comparisons.  It seems to me there isn't anything hugely sexy in this work, but there is a huge amount of work that sets the evolutionary relationships between these Drosopholids in context.  It's also an opportunity to expound on chromosomes in Drosophila!