Vanishing chromosomal inversion clines in Drosophila subobscura from Chile: Is behavioral thermoregulation to blame?

Chromosomal inversion clines paralleling the long-standing ones in native Palearctic populations of Drosophila subobscura evolved swiftly after this species invaded the Americas in the late 1970s and early 1980s. However, the new clines did not consistently continue to converge on the Old World baseline. Our recent survey of Chilean populations of D. subobscura shows that inversion clines have faded or even changed sign with latitude. Here, we investigate the hypothesis that this fading of inversion clines might be due to the Bogert effect, namely, that flies' thermoregulatory behavior has eventually compensated for environmental variation in temperature, thus buffering selection on thermal-related traits. We show that latitudinal divergence in thermal preference (T-p) has evolved in Chile for females, with higher-latitude flies having a lower mean T-p. Plastic responses in T-p also lessen latitudinal thermal variation because flies developed at colder temperatures prefer warmer microclimates. Our results are consistent with the idea that active behavioral thermoregulation might buffer environmental variation and reduce the potential effect of thermal selection on other traits as chromosomal arrangements.

Scientific evidence on the usefulness of intraarticular hyaluronic acid injection in the management of temporomandibular dysfunction

Hyaluronic acid (HA) is found in high concentrations in cartilage and synovial fluid, and is an important component of the extracellular matrixes- exerting joint lubrication and buffering actions thanks to its viscoelastic properties. The present study examines the scientific evidence found in the current literature on the usefulness of the intraarticular injection of HA in patients with temporomandibular dysfunction. A literature search was made up until May 2008 in the following databases: PubMed / MEDLINE. Of the articles found in the literature, the present review included 18 relevant studies on the application of HA in the temporomandibular joint (TMJ). The quality, level of evidence and strength of recommendation of the articles was evaluated based on the"Strength of Recommendation Taxonomy" criteria. It is concluded that type A level of recommendation exists in favor of the intraarticular injection of HA in dysfunction of the TMJ. However, further studies are needed to establish the true therapeutic effects and to identify the best dosing regimen.