A Blog Around The Clock

New and Exciting in PLoS this week

Let’s check all seven PLoS journals tonight…. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Mendeley, Connotea, Stumbleupon, Facebook and Digg) with just one click. Here are my own picks for the week – you go and look for your own favourites:

Molecular Phylogenetics of the Genus Neoconocephalus (Orthoptera, Tettigoniidae) and the Evolution of Temperate Life Histories:

The katydid genus Neoconocephalus (25+ species) has a prominent acoustic communication system and occurs in large parts of the Neotropics and Nearctic. This group has been subject of numerous behavioral, physiological, and evolutionary studies of its acoustic communication system. Two distinct life histories occur in this group: The tropical life history incorporates multiple generations/year and direct egg development without environmental triggers. Temperate life history is characterized by overwintering in the egg stage, cold trigger of egg development, and one generation/year. This study reconstructs the phylogenetic relationships within the genus to (1) determine the evolutionary history of the temperate life history, and (2) to support comparative studies of evolutionary and physiological problems in this genus. We used Amplified Fragment Length Polymorphisms (AFLP), and sequences of two nuclear loci and one mitochondrial locus to reconstruct phylogenetic relationships. The analysis included 17 ingroup and two outgroup species. AFLP and mitochondrial data provided resolution at the species level while the two nuclear loci revealed only deeper nodes. The data sets were combined in a super-matrix to estimate a total evidence tree. Seven of the temperate species form a monophyletic group; however, three more temperate species were placed as siblings of tropical species. Our analyses support the reliability of the current taxonomic treatment of the Neoconocephalus fauna of Caribbean, Central, and North America. Ancestral state reconstruction of life history traits was not conclusive, however at least four transitions between life histories occurred among our sample of species. The proposed phylogeny will strengthen conclusions from comparative work in this group.

Cost-Effectiveness of a Telephone-Delivered Intervention for Physical Activity and Diet:

Given escalating rates of chronic disease, broad-reach and cost-effective interventions to increase physical activity and improve dietary intake are needed. The cost-effectiveness of a Telephone Counselling intervention to improve physical activity and diet, targeting adults with established chronic diseases in a low socio-economic area of a major Australian city was examined. A cost-effectiveness modelling study using data collected between February 2005 and November 2007 from a cluster-randomised trial that compared Telephone Counselling with a “Usual Care” (brief intervention) alternative. Economic outcomes were assessed using a state-transition Markov model, which predicted the progress of participants through five health states relating to physical activity and dietary improvement, for ten years after recruitment. The costs and health benefits of Telephone Counselling, Usual Care and an existing practice (Real Control) group were compared. Telephone Counselling compared to Usual Care was not cost-effective ($78,489 per quality adjusted life year gained). However, the Usual Care group did not represent existing practice and is not a useful comparator for decision making. Comparing Telephone Counselling outcomes to existing practice (Real Control), the intervention was found to be cost-effective ($29,375 per quality adjusted life year gained). Usual Care (brief intervention) compared to existing practice (Real Control) was also cost-effective ($12,153 per quality adjusted life year gained). This modelling study shows that a decision to adopt a Telephone Counselling program over existing practice (Real Control) is likely to be cost-effective. Choosing the ‘Usual Care’ brief intervention over existing practice (Real Control) shows a lower cost per quality adjusted life year, but the lack of supporting evidence for efficacy or sustainability is an important consideration for decision makers. The economics of behavioural approaches to improving health must be made explicit if decision makers are to be convinced that allocating resources toward such programs is worthwhile.

Blasting Off on an Actin Comet Tail:

Cells have structure and the ability to move, thanks in part to the actin cytoskeleton, a dynamic cellular scaffolding that facilitates many cellular processes. Actin is mostly concentrated near the outer membrane of the cell, where it is involved in such processes as the formation of membrane protrusions at the leading edges of migrating cells, the movement of certain intracellular vesicles such as endosomes, and the generation of the cleavage furrow during cell division. In this issue of PLoS Biology, Mark Dayel and colleagues combine computer modeling with in vitro experiments to explain some of the fundamental dynamics of actin polymerization that underlie these diverse phenomena.

Can the Error Detection Mechanism Benefit from Training the Working Memory? A Comparison between Dyslexics and Controls — An ERP Study:

Based on the relationship between working memory and error detection, we investigated the capacity of adult dyslexic readers’ working memory to change as a result of training, and the impact of training on the error detection mechanism. 27 dyslexics and 34 controls, all university students, participated in the study. ERP methodology and behavioral measures were employed prior to, immediately after, and 6 months after training. The CogniFit Personal Coach Program, which consists of 24 sessions of direct training of working memory skills, was used. Both groups of readers gained from the training program but the dyslexic readers gained significantly more. In the dyslexic group, digit span increased from 9.84±3.15 to 10.79±3.03. Working memory training significantly increased the number of words per minute read correctly by 14.73%. Adult brain activity changed as a result of training, evidenced by an increase in both working memory capacity and the amplitude of the Error-related Negativity (ERN) component (24.71%). When ERN amplitudes increased, the percentage of errors on the Sternberg tests decreased. We suggest that by expanding the working memory capacity, larger units of information are retained in the system, enabling more effective error detection. The crucial functioning of the central-executive as a sub-component of the working memory is also discussed.

Improving the Quantitative Basis of the Surgical Burden in Low-Income Countries:

For decades, the primary health care paradigm with a focus on maternal and child health programs has been driving funding for health in developing countries [1]. This has led to improvements, although there are doubts that many countries will meet the ambitious Millennium Development Goals 4 and 5 of reducing maternal and childhood mortality by three-quarters and two-thirds, respectively, between 1990 and 2015 [2],[3]. Surgery has not traditionally been considered an essential component of primary health care in low-income countries. This may be changing [4]. Emergency obstetric care, including surgical interventions, is now recognized as a key health service component for reducing maternal and neonatal mortality [5]. The broader contribution of surgical services to improvements in health outcomes in developing countries is also being discussed [6]-[9].

Natural Infection of the Ground Squirrel (Spermophilus spp.) with Echinococcus granulosus in China:

Echinococcus granulosus and E. multilocularis are important zoonotic pathogens that cause serious disease in humans. E. granulosus can be transmitted through sylvatic cycles, involving wild carnivores and ungulates; or via domestic cycles, usually involving dogs and farm livestock. E. multilocularis is primarily maintained in a sylvatic life-cycle between foxes and rodents. As part of extensive investigations that we undertook to update available epidemiological data and to monitor the transmission patterns of both E. granulosus and E. mulilocularis in Ningxia Hui Autonomous Region (NHAR) in northwest China, we captured small mammals on the southern slopes of Yueliang Mountain, Xiji, an area co-endemic for human alveolar echinococcosis and cystic echinococcosis. Of 500 trapped small mammals (mainly ground squirrels; Spermophilus dauricus/alashanicus), macroscopic cyst-like lesions (size range 1-10 mm) were found on the liver surface of approximately 10% animals. One of the lesions was shown by DNA analysis to be caused by E. granulosus and by histology to contain viable protoscoleces. This is the first report of a natural infection of the ground squirrel with E. granulosus. We have no definitive proof of a cycle involving ground squirrels and dogs/foxes but it is evident that there is active E. granulosus transmission occurring in this area.

Evidence for Habitual and Goal-Directed Behavior Following Devaluation of Cocaine: A Multifaceted Interpretation of Relapse:

Cocaine addiction is characterized as a chronically relapsing disorder. It is believed that cues present during self-administration become learned and increase the probability that relapse will occur when they are confronted during abstinence. However, the way in which relapse-inducing cues are interpreted by the user has remained elusive. Recent theories of addiction posit that relapse-inducing cues cause relapse habitually or automatically, bypassing processing information related to the consequences of relapse. Alternatively, other theories hypothesize that relapse-inducing cues produce an expectation of the drug’s consequences, designated as goal-directed relapse. Discrete discriminative stimuli signaling the availability of cocaine produce robust cue-induced responding after thirty days of abstinence. However, it is not known whether cue-induced responding is a goal-directed action or habit. We tested whether cue-induced responding is a goal-directed action or habit by explicitly pairing or unpairing cocaine with LiCl-induced sickness (n = 7/group), thereby decreasing or not altering the value of cocaine, respectively. Following thirty days of abstinence, no difference in responding between groups was found when animals were reintroduced to the self-administration environment alone, indicating habitual behavior. However, upon discriminative stimulus presentations, cocaine-sickness paired animals exhibited decreased cue-induced responding relative to unpaired controls, indicating goal-directed behavior. In spite of the difference between groups revealed during abstinent testing, no differences were found between groups when animals were under the influence of cocaine. Unexpectedly, both habitual and goal-directed responding occurred during abstinent testing. Furthermore, habitual or goal-directed responding may have been induced by cues that differed in their correlation with the cocaine infusion. Non-discriminative stimulus cues were weak correlates of the infusion, which failed to evoke a representation of the value of cocaine and led to habitual behavior. However, the discriminative stimulus-nearly perfectly correlated with the infusion-likely evoked a representation of the value of the infusion and led to goal-directed behavior. These data indicate that abstinent cue-induced responding is multifaceted, dynamically engendering habitual or goal-directed behavior. Moreover, since goal-directed behavior terminated habitual behavior during testing, therapeutic approaches aimed at reducing the perceived value of cocaine in addicted individuals may reduce the capacity of cues to induce relapse.

Ten Simple Rules for Chairing a Scientific Session:

Chairing a session at a scientific conference is a thankless task. If you get it right, no one is likely to notice. But there are many ways to get it wrong and a little preparation goes a long way to making the session a success. Here are a few pointers that we have picked up over the years.

Wonderful Life: An Interview with Herb Boyer:

Once upon a time, not so very long ago, before restriction enzymes were ordered from a New England Biolabs catalog and vectors arrived in neat packages from Promega, and before molecular biologists added patents or a company to their CV, there was Herb Boyer. One can almost define the revolution in molecular genetics by Herb’s story alone–the discovery of the iconic restriction enzyme EcoR1 and the definition of its sticky ends, the collaboration with Stan Cohen that produced recombinant DNA, and the genesis of the enduring gold standard in biotechnology, Genentech.

I had been fascinated by Herb’s story for many years, as I myself had the good fortune to do a post-doc at Genentech in the early 1980s. Much has been written about Herb Boyer (Image 1), so I chose not to talk with him about his role in the founding of Genentech in 1976, nor the landmark Boyer-Cohen patent, nor the mid-1970s moratorium on recombinant DNA research. Instead, I was interested in what came before all of that–how Herb developed as a scientist, how he become interested in restriction enzymes and in vitro recombination–and by what came later. I’m sure you’ll agree, this is equally rich reading.

Five Questions about Microsporidia:

Microsporidia are a diverse group of obligate intracellular eukaryotic parasites. There are approximately 1,300 formally described species in 160 genera [1], but this certainly represents a tiny fraction of the real diversity because most potential host lineages have been poorly surveyed. Nearly all microsporidia are known to infect animals, and some are responsible for a number of human diseases (13 species of microsporidia have been documented to infect humans) predominantly associated with immune suppression [2]. They also infect several commercially important animal species such as bees, silk worms, and salmon, and various domesticated mammals. They are thought to be especially common in insects and fish, although most invertebrates have been so poorly surveyed this may change. Their infective stage is a thick-walled spore, which is also the only stage that can survive outside their host cell [3]. The spore contains a sophisticated infection apparatus, primarily distinguished by a long, coiled filament called the polar filament. When the spore germinates, an inflow of water leads to pressure in the spore that eventually ruptures the wall and forces the polar filament to eject, turning inside out to form a tube (Figure 1) [4]. This process takes place very quickly, so the polar tube is in effect a projectile. At the completion of germination, the parasite cytoplasm is forced through the tube and either delivered to the surface of the host cell, or perhaps injected into the host cytoplasm if the projectile tube has actually penetrated the host cell. It has also been shown that microsporidia can be taken up by phagocytosis, and then use the polar tube to escape from the vacuole [5], so there appear to be more than one mode of infection.