Larvicidal effect of pepper plants on Aedes aegypti (L.) (Diptera: Culicidae).

Ethanolic extracts derived from three species of the Piperaceae (pepper) family, Piper longum L., P. ribesoides Wall., and P. sarmentosum Roxb. ex Hunt., were evaluated for efficacy against early 4th instar larvae of Aedes aegypti mosquitoes using larvicidal bioassays. The highest larvicidal efficacy was established from P. longum, followed by P. sarmentosum and P. ribesoides, with LC50 values of 2.23, 4.06, and 8.13 ppm, respectively. Observations of morphological alterations on treated 4th instar larvae revealed that most organs, except anal papillae, had a normal structural appearance that was similar to controls. Under light microscopy, the internal structures of anal papillae in the treated larvae showed shrinkage, while the external features were normal in appearance. Ultrastructural studies, however, clearly demonstrated external destruction, with extensive damage and shrunken cuticle of the anal papillae. The structural deformation of anal papillae probably led to their dysfunction, which may be intrinsically associated with the death of the larvae. This study affords some evidence regarding the action site of the pepper extracts and suggests their potential in developing new types of larvicides used for mosquito control.     

A Cost of Leadership in Human Groups

Group living is the result of a dynamic trade‐off between associated costs and benefits. However, these costs and benefits are not necessarily distributed equally across different spatial positions of groups which may result in different fitness returns for individuals occupying different positions in groups. Here we consider whether leadership of a group during a navigation task in humans may have a specific cost associated with it. Pairs of students performed a counting task whilst walking through two obstacle courses, once as leader and once as follower. We found that leaders made significantly more errors in the counting task than followers suggesting that there is an attention cost associated with leadership/navigation behaviour.     

Echinostoma revolutum: Freshwater Snails as the Second Intermediate Hosts in Chiang Mai,Thailand

The occurrence of 37-collar spined echinostome metacercariae in freshwater snails was investigated in 6 districts of Chiang Mai Province, Thailand, from October 2011 to April 2012. A total of 2,914 snails that belong to 12 species were examined, and 7 snail species (Clea helena, Eyriesia eyriesi, Bithynia funiculata, Bithynia siamensis siamensis, Filopaludina doliaris, Filopaludina sumatrensis polygramma, and Filopaludina martensi martensi) were found infected with echinostome metacercariae. The prevalence of metacercariae was the highest in Filopaludina spp. (38.5-58.7%) followed by B. funiculata (44.0%), E. eyriesi (12.5%), B. siamensis siamensis (8.2%), and C. helena (5.1%). Metacercariae were experimentally fed to hamsters and domestic chicks, and adult flukes were recovered from both hosts at days 15 and 20 post-infection. The adult flukes were identified based on morphological features, morphometrics, host-parasite relationships, and geographical distribution. They were compatible to Echinostoma revolutum or Echinostoma jurini, with only minor differences. As the adults were recovered from both hamsters and chicks, our specimens were more compatible to E. revolutum rather than E. jurini (reported only from mammals). This is the first report for metacercariae of E. revolutum in the snail host, C. helena, and also confirmed that Filopaludina spp., E. eryresi, and Bithynia spp. act as the second intermediate hosts of E. revolutum under natural conditions, which are indigenously distributed in Chiang Mai province.     

Quantitative EEG evaluation for performance level analysis of professional female soccer players

Quantitative electroencephalography (QEEG) was used to investigate the brain activity of Thai professional female soccer team players who exhibit high performance. The QEEGs of 29 players were recorded three times: twice before a competition (once a week) and a week after a competition. The results of the brain topographic map (absolute power) in the alpha frequency band and the brain connectivity (coherence) in the delta frequency bands represented their anxiety and decision-making levels, respectively. These phenomena occurred in the brain activities of the athletes, which could be used to predict their performances during the competition. Moreover, the value of the correlation coefficient between the brain activity ranking and average performance score revealed a moderate to good relationship (r_s = .586, p = .001). These results support the association between brain activity and performance level during competition.     

Biotinyl-methyl 4-(amidomethyl)benzoate is a competitive inhibitor of human biotinidase

Posttranslational modification of histones by biotinylation can be catalyzed by both biotinidase (BTD) and holocarboxylase synthetase. Biotinylation of histones is an important epigenetic mechanism to regulate gene expression, DNA repair, and chromatin remodeling. The role of BTD in histone biotinylation is somewhat ambiguous, given that BTD also catalyzes removal of the biotin tag from histones. Here, we sought to develop BTD inhibitors for future studies of the role of BTD in altering chromatin structure. We adopted an existing colorimetric BTD assay for use in a novel 96-well plate format to permit high-throughput screening of potential inhibitors. Biotin analogs were chemically synthesized and tested for their ability to inhibit human BTD. Seven of these compounds inhibited BTD by 26–80%. Biotinyl-methyl 4-(amidomethyl)benzoate had the largest effect on BTD, causing an 80% inhibition at 1 mM concentration. Enzyme kinetics studies were conducted to determine V_max, K_m and K_i for the seven inhibitors; kinetics were consistent with the hypothesis that biotinyl-methyl 4-(amidomethyl)benzoate and the other compounds acted by competitive inhibition of BTD. Finally, biotinyl-methyl 4-(amidomethyl)benzoate did not affect biotin transport in human cells, suggesting specificity in regard to biotin-related processes.