Endothelial cells of adipose tissues: A niche of adipogenesis

Comment on: Tran KV, et al. Cell Metab 2012; 15:222-9.     

Historical biogeography of the widespread macroalga Sargassum (Fucales,Phaeophyceae)

Sargassum is a cosmopolitan brown algal genus spanning the three ocean basins of the Atlantic, Pacific and Indian Oceans, inhabiting temperate, subtropical and tropical habitats. Sargassum has been postulated to have originated in the Oligocene epoch approximately 30 mya according to a broad phylogenetic analysis of brown macroalgae, but its diversification to become one of the most widespread and speciose macroalgal genera remains unclear. Here, we present a Bayesian molecular clock study, which analyzed data from the order Fucales of the brown algal crown radiation (BACR) group to reconstruct a time-calibrated phylogeny of the Sargassum clade. Our phylogeny included a total of 120 taxa with 99 Sargassum species sampled for three molecular markers – ITS-2, cox3 and rbcLS – calibrated with an unambiguous Sargassaceae fossil from between the lower and middle Miocene. The analysis revealed a much later origin of Sargassum than expected at about 6.7 mya, with the genus diversifying since approximately 4.3 mya. Current geographic distributions of Sargassum species were then analyzed in conjunction with the time-calibrated phylogeny using the dispersal-extinction-cladogenesis (DEC) model to estimate ancestral ranges of clades in the genus. Results strongly support origination of Sargassum in the Central Indo-Pacific (CIP) region with subsequent independent dispersal events into other marine realms. The longer history of diversification in the ancestral CIP range could explain the much greater diversity there relative to other marine areas today. Analyses of these dynamic processes, when fine-tuned to a higher spatial resolution, enable the identification of evolutionary hotspots and provide insights into long-term dispersal patterns.     

Epidemiology and prediction of brown leaf rust of mulberry caused by Peridiopsora mori

Brown leaf rust (BLR) caused by Peridiopsora mori is one of the major foliar diseases of mulberry (Morus sp.) in the subtropical hills of eastern India. The disease appeared in first week of August and continued up to September with maximum severity in second and third week of September. The disease symptoms appeared at atmospheric temperature (27.00–20.07°C), relative humidity (92.14–82.43%), rainfall (11.20 cm) and rainy days (7) of the preceding week. Disease severity (>50 PDI) was observed at temperature (26.29–19.29°C), relative humidity (94.14–80.14%), rainfall (4.12 cm) and number of rainy days (2–3 days). Apparent rate of infection was found high at temperature (27.00–19.83°C), relative humidity (94.67–85.00%), rainfall (4.6 cm) and rainy days (2) of the preceding week. The correlation coefficient between disease severity and average meteorological factors of the preceding 7 days revealed that BLR disease severity showed significant negative correlation with minimum temperature. It was also revealed that contribution of maximum and minimum temperature 42.23% and 35.21%, maximum and minimum relative humidity (RH) 11.23% and 10.69% and rainfall and number of rainy days 0.11% and 0.50%, respectively towards development of BLR disease severity. Multiple regression analysis revealed that average of maximum and minimum temperatures and minimum RH of preceding 7 days were found to maximally influence BLR disease severity.     

Rice Resistance to Planthoppers and Leafhoppers

For over 50 years, host-plant resistance has been regarded as an efficient method to reduce yield losses to rice caused by delphacid and cicadelid hoppers. Already a number of resistant rice varieties have been developed and deployed throughout Asia. To date, over 70 hopper resistance genes have been identified in rice; however, less than 10 genes have been deliberately introduced to commercial rice varieties. Currently, due to recent brown planthopper (Nilaparvata lugens [Stål]) and whitebacked planthopper (Sogatella furcifera [Horvath]) outbreaks occurring at an unprecedented scale, researchers are working toward a second generation of resistant varieties using newly identified gene loci and applying new molecular breeding methods. This paper reviews advances in the identification of resistance genes and QTLs against hoppers in rice. It collates all published information on resistance loci and QTLs against the major rice planthoppers and leafhoppers and presents information on gene locations, genetic markers, differential varieties, and wild rice species as sources of resistance. The review indicates that, whereas progress in the identification of genes has been rapid, considerable tidying of the information is required, especially regarding gene nomenclature and resistance spectra. Furthermore, sound information on gene functioning is almost completely lacking. However, hopper responses to resistance mechanisms are likely to be similar because a single phenotyping technique has been applied by most national and international breeding programs during germplasm screening. The review classifies genes occurring at two chromosome regions associated with several identified resistance loci and highlights these (Chr4S: BphR-R and Chr12L: BphR-R) as general stress response regions. The review calls for a greater diversity of phenotyping methods to enhance the durability of resistant varieties developed using marker-aided selection and emphasizes a need to anticipate the development of virulent hopper populations in response to the field deployment of genes.     

Species Diversity,Phylogeny and Large Scale Biogeographic Patterns of the Genus Padina (Phaeophyceae,Dictyotales)

The brown algal genus Padina (Dictyotales, Phaeophyceae) is distributed worldwide in tropical and temperate seas. Global species diversity and distribution ranges, however, remain largely unknown. Species‐level diversity was reassessed using DNA‐based, algorithmic species delineation techniques based on cox3 and rbcL sequence data from 221 specimens collected worldwide. This resulted in estimates ranging from 39 to 61 putative species (ESUs), depending on the technique as well as the locus. We discuss the merits, potential pitfalls, and evolutionary and biogeographic significance of algorithmic species delineation. We unveil patterns whereby ESUs are in all but one case restricted to either the Atlantic or Indo‐Pacific Ocean. Within ocean basins we find evidence for the vast majority of ESUs to be confined to a single marine realm. Exceptions, whereby ESUs span up to three realms, are located in the Indo‐Pacific Ocean. Patterns of range‐restricted species likely arise by repeated founder events and subsequent peripatric speciation, hypothesized to dominate speciation mechanisms for coastal marine organisms in the Indo‐Pacific. Using a three‐gene (cox3, psaA and rbcL), relaxed molecular clock phylogenetic analysis we estimated divergence times, providing a historical framework to interpret biogeographic patterns.     

Evaluation of an indigenous parasitoid Habrobracon gelechiae (Hymenoptera: Braconidae) for biological control of light brown apple moth Epiphyas postvittana (Lepidoptera: Tortricidae) in California

Light brown apple moth, Epiphyas postvittana (Walker), is a newly invasive pest in California. Habrobracon gelechiae Ashmead is an indigenous North American ectoparasitoid of lepidopterans. Using E. postvittana as the host, we determined H. gelechiae host stage preference for oviposition and suitability for larval growth: the parasitoid attacked second to fifth instars, but preferred older (third to fifth) host larvae for oviposition, laying more eggs per clutch on the largest (fifth instar). Offspring survival was better on larger (third to fifth instars) hosts. Adult survival and fecundity and immature temperature development were studied at three key temperatures. At 12°C, H. gelechiae failed to oviposit. At 22 and 30°C, H. gelechiae had, respectively, egg to adult developmental times of 15.4 and 8.7 days, adult female survival of 54.8 and 27.2 days, lifetime parasitism of 39.9 and 21.8 hosts and 181 and 151 eggs per female, an intrinsic rate of increase of 0.107 and 0.165, and mean generation time 30.7 and 18.9 days. We studied intraguild interactions with the endoparasitoid Meteorus ictericus Nees, and found that H. gelechiae did not discriminate against hosts that were parasitised by M. ictericus. Neither the paralysing venom injected by H. gelechiae or the presence of the ectoparasitoid's eggs or larvae arrested M. ictericus development. We also conducted a field release of H. gelechiae on two plant species commonly infested by E. postvittana and showed that H. gelechiae was able to locate and attack moth larvae on both hosts.