` This bonus post is pretty old, and there's not much to it. I can't add anything intelligent to it because I'm surrounded by stuff. Also, it's similar to the last one because I'm mostly venting and have no time to make it in any way tasteful.
` Look at all the lovely Nature articles I'm missing because I won't pay them money:
The genetic code 'cracked',protein synthesis 'solved' and complete genomes sequenced: surely we now know what a gene is and what it does. That may be true for those safely outside the field. But for geneticists close to the action, the concept of a gene is getting very complicated indeed.
News Feature: Genetics: What is a gene?
The idea of genes as beads on a DNA string is fast fading. Protein-coding sequences have no clear beginning or end and RNA is a key part of the information package, reports Helen Pearson.
25 May 2006
A healthy distance
Social animals gain a lot by pooling resources — but they stand to lose a lot if they also pool pathogens. The Caribbean spiny lobster has developed a way of reducing this risk. Normally they share an underwater shelter with others of the species: but healthy individuals recognize and steer clear of those infected with the lethal virus PaV1. It is possible that infection alters the visual displays used to establish social groups, but the signs are that this avoidance strategy is chemically mediated.
Brief Communications: Ecology: Avoidance of disease by social lobsters
These gregarious animals shun lobsters that carry a lethal virus, even when they still seem to be healthy.
Donald C. Behringer, Mark J. Butler and Jeffrey D. Shields
Nature 441, 421 (25 May 2006) | doi:10.1038/441421a; Published online 24 May 2006
Ecology: Avoidance of disease by social lobsters
Transmissible pathogens are the bane of social animals1, so they have evolved behaviours to decrease the probability of infection2, 3. There is no record, however, of social animals avoiding diseased individuals of their own species in the wild. Here we show how healthy, normally gregarious Caribbean spiny lobsters (Panulirus argus) avoid conspecifics that are infected with a lethal virus. Early detection and avoidance of infected, though not yet infectious, individuals by healthy lobsters confers a selective advantage and highlights the importance of host behaviour in disease transmission among natural populations.
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23529, USA
- Virginia Institute of Marine Science, Gloucester Point, Virginia 23062, USA
Nature 441, 506-508 (25 May 2006) | doi:10.1038/nature04591; Received 4 November 2005; Accepted 18 January 2006
Homology of arthropod anterior appendages revealed by Hox gene expression in a sea spider
Arthropod head segments offer a paradigm for understanding the diversification of form during evolution, as a variety of morphologically diverse appendages have arisen from them. There has been long-running controversy, however, concerning which head appendages are homologous among arthropods, and from which ancestral arrangement they have been derived. This controversy has recently been rekindled by the proposition that the probable ancestral arrangement, with appendages on the first head segment, has not been lost in all extant arthropods as previously thought, but has been retained in the pycnogonids, or sea spiders1. This proposal was based on the neuroanatomical analysis of larvae from the sea spider Anoplodactylus sp., and suggested that the most anterior pair of appendages, the chelifores, are innervated from the first part of the brain, the protocerebrum. Our examination of Hox gene expression in another sea spider, Endeis spinosa, refutes this hypothesis. The anterior boundaries of Hox gene expression domains place the chelifore appendages as clearly belonging to the second head segment, innervated from the second part of the brain, the deutocerebrum. The deutocerebrum must have been secondarily displaced towards the protocerebrum in pycnogonid ancestors. As anterior-most appendages are also deutocerebral in the other two arthropod groups, the Euchelicerata and the Mandibulata, we conclude that the protocerebral appendages have been lost in all extant arthropods.
- Université Pierre et Marie Curie-Paris 6, UMR 7138 CNRS UPMC MNHN ENS IRD, Case 05, 9 quai St Bernard, 75005 Paris, France
- Université Pierre et Marie Curie-Paris 6, UMR 7622 CNRS UPMC, 9 quai St Bernard, 75005 Paris, France
- †Present addresses: Muséum National d'Histoire Naturelle, UMR 5202 CNRS, Département Systématique et Evolution, case 50, 45 rue Buffon, 75005 Paris, France (J.M.); Department of Biology, Evolutionary Biology, University of Konstanz, D-78457 Konstanz, Germany (C.C.)
25 May 2006
The arthropods are a good example of how evolution shapes different body forms from a single ancestral species. They consist of a series of head and body segments, each with different appendages — claws, antennae, wings, legs. A recent Nature paper offered a new explanation of some apparent anomalies. The curious arthropods called sea spiders, it was suggested, have appendages on the first head segment, providing a link with the arthropod ancestor. That work was based on neuroanatomical observations, but now, using molecular techniques, Jager et al. show that sea spiders, like all other living arthropods, have lost the first head appendages seen in fossils.
Letter: Homology of arthropod anterior appendages revealed by Hox gene expression in a sea spider
Muriel Jager, Jérôme Murienne, Céline Clabaut, Jean Deutsch, Hervé Le Guyader and Michaël Manuel
Nature 441, 509-512 (25 May 2006) | doi:10.1038/nature04756; Received 28 November 2005; Accepted 30 March 2006
Somatic stem cell niche tropism in Wolbachia
Wolbachia are intracellular bacteria found in the reproductive tissue of all major groups of arthropods1, 2. They are transmitted vertically from the female hosts to their offspring, in a pattern analogous to mitochondria inheritance. But Wolbachia phylogeny does not parallel that of the host, indicating that horizontal infectious transmission must also occur3, 4, 5. Insect parasitoids are considered the most likely vectors, but the mechanism for horizontal transfer is largely unknown4, 6, 7. Here we show that newly introduced Wolbachia cross several tissues and infect the germline of the adult Drosophila melanogaster female. Through investigation of bacterial migration patterns during the course of infection, we found that Wolbachia reach the germline through the somatic stem cell niche in the D. melanogaster germarium. In addition, our data suggest that Wolbachia are highly abundant in the somatic stem cell niche of long-term infected hosts, implying that this location may also contribute to efficient vertical transmission. This is, to our knowledge, the first report of an intracellular parasite displaying tropism for a stem cell niche.
- Howard Hughes Medical Institute,
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08540, USA
25 May 2006
A niche fit for Wolbachia
Wolbachia are remarkably successful intracellular parasites. They are found in most Arthropods and are also in the news as possible tools for malaria control — transgenic variants could block maturation of malaria parasites in mosquitoes. Like mitochondria, these bacteria are transmitted by the mother. They also spread horizontally between species, but little is known about the cellular mechanisms involved. Frydman et al. now report that Wolbachia can cross tissue barriers to reach the germline. They preferentially populate the somatic stem cell niche of the Drosophila germarium (where the ova form) in newly initiated or inherited infections. The stem cell niche appears to act as a reservoir of bacteria for germline infection.
Letter: Somatic stem cell niche tropism in Wolbachia
Horacio M. Frydman, Jennifer M. Li, Drew N. Robson and Eric Wieschaus
` Hee. And here's another: Practice patterns of Japanese physicians in urologic surveillance and management of spinal cord injury patients
S Kitahara, E Iwatsubo, K Yasuda, T Ushiyama, H Nakai, T Suzuki, T Yamashita, R Sato, T Kihara, T Yamanishi and Y Nohara
` And, if you snooze, ya lose - the articles I can access disappear, and so I'm also too late for these:
Stressed-out plants warn their offspring
Increased tendency to mutate is handed down to next generation.
6 August 2006
How a leopard changes his spots
Equations get to grips with patterns in a growing cat's coat.
4 August 2006
Japan aims to build Moon base by 2030
Ambitious plan surprises fellow space agencies.
3 August 2006
Mice saved from lethal allergic reaction
Protein discovery reveals mechanism of anaphylactic shock.
2 August 2006
It's official: apes outsmart monkeys
Primate IQ test hails orang-utans as our smartest relatives.
1 August 2006
` Alas, I cannot read all these. The best I can do is to find copies of them elsewhere and to act fast. If only relatively reliable information could be free....