For much of my professional career as a Drosophila geneticist I've worked with polytene chromosomes, and it's always interesting to see papers with interesting tidbits of information about their structure and function. Polytene chromosomes are those rather strange structures formed from high levels of chromosome endoreduplication (see this blog article for a detailed description). Polytene chromosomes are widespread in flies, and in Drosophila are mostly studied in the larval salivary glands where they are easy to work with: Calvin Bridges used salivary gland polytene chromosomes to construct his polytene chromosome map. In this paper, Tom Hartl and colleagues show Condensin complexes (which have a function in chromosome condensation and anaphase chromosome segregation; and in vitro can induce and trap DNA supercoiling) can cause polytene chromosome disassembly and antagonise transvection.  Their data link processes of chromosome condensation and DNA supecoiling with higher order interphase nuclear structure that impacts on gene expression.

Unlike salivary gland polytene chromosomes, those of ovarian nurse cells break down during the development of the nurse cells, at about mid-oogenesis.  In this paper, two mutant alleles of a predicted component of the condensin II complex, Cap-H2 are studied.  In flies mutant for Cap-H2, the nurse cell polytene chromosomes don't disassemble.

This recent paper caught my eye, as as some of my recent research has related to the regulation of antimicrobial defence in Drosophila.  Insects have a two ways of coping with microbial infection.  Firstly, microbes may be dealt with by circulating blood cells (haemocytes) of which there are several classes.  Haemocytes to no play any role in respiration in insects.  A second means of controlling microbes involves several peptides that kill bacteria or fungi:  these are usually expressed in response to the presence of microbes in the haemolymph.  Interestingly, this induced system has a counterpart in vertebrates.  It's generally thought that the important system in clearing pathogenic microbes in insects is the induced antimicrobial peptides.  This paper investigates the roles of both systems.

The authors have evaluated the relative use of these two mechanisms of infection control in Tenebrio molitorI, the mealworm (picture above).  Their hypothesis is that the haemocytes represent the first line of defence, with the induced response of antimicrobial peptides mopping up microbes remaining from the first round defence.  In this model, the induced antimicrobial response largely functions to eliminate suviving pathogens that may be refractory to the first line of defence.

Here's a brief update on the BT Total Censorship and the general BT-Webwise situation - for more background, see part 1 and part 2, and follow this thread at the nodpi.org forum. 

PC World - UK Prosecutors Investigate BT Over Online Ad System PC World magazine pick up on stories that the Crown Prosecution Service is now investigating illegal interception conducted by BT in 2006 and 2007.

Section 41 blog - Two Conferences Raise Concerns over Phorm  Reports from two recent conferences on internet privacy, in which BT's activity came in for comment.

There's an interesting news article in Science, entitled Last Stand for the Body Snatcher of the Himalayas?, concerning a fungus with quite unusual habits.  The full citation can be found at the end of this article.

Cordyceps sinensis is a pretty strange fungus - it infects ghost moth caterpillars, and in doing so alters their behaviour such that when they hibernate for the winter, they orient themselves on end and near to the surface.  Over the winter, the fungus consumes the caterpillar and eventually pushes a fruiting body above ground.  In the picture below, you can see remnants of the caterpillar, from which the brown 'mushroom' protrudes (picture from wikipedia).

A group of contributors to the nodpi.org website braved the vile elements in Manchester to hand out leaflets outside the "Privacy by Design" meeting, to highlight issues surrounding the vile Phorm and BT's implementation BT Webwise.  Here is their report.

So, what's the point of having scientific advisors if you plain ignore what they tell you?  A group of scientists have written to The Guardian urging the House of Lords to look at scientific evidence and hold off from reclassifying cannabis from C to B.  (Ben Goldacre's Bad Science blog has featured media misrepresentation of cannabis)

The Register reports that the Home Secretary ignored her advisors, the Advisory Council on the Misuse of Drugs (ACMD), and proposes re-classifying the drug.

This interesting paper investigates whether there is a relationship between polyandry and selfish genetic elements, in the fruit fly Drosophila pseudoobscura. 

Polyandry - where females have multiple mating partners - is widespread in animals, but despite its frequency, little is known of the costs and benefits of this reproductive strategy (though this paper cites evidence that the costs of multiple mating appear to outweigh the benefits.  It is likely that the benefits lie in that polyandry gives the female a greater degree of control over paternity, via sperm competition.  There is also a possibility that selfish genetic elements may promote polyandry by correlating male fitness with sperm competition.

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!

The latest publication from our project investigating a Drosophila homologue of WRN exonuclease is now online.  

Ivan Boubriak, Penelope A. Mason, David J. Clancy, Joel Dockray, Robert D. C. Saunders, Lynne S. Cox (2008). DmWRNexo is a 3′–5′ exonuclease: phenotypic and biochemical characterization of mutants of the Drosophila orthologue of human WRN exonuclease Biogerontology DOI: 10.1007/s10522-008-9181-3

This is my third posting on my upgrade experiences with Ubuntu 8.10 'Intrepid Ibex' (see Ubuntu 8.10 'Intrepid Ibex' upgrades and Ubuntu 8.10 'Intrepid Ibex' update.  In the second of those postings, I reported that an attempt to project from my laptop borked all my nice Compiz desktop effects. 

This morning I made one last ditch attempt to resolve this before reinstalling 8.10 - and succeeded. This was in part due to advice in this thread at ubuntuforums.org.