Vital role for the Plasmodium actin capping protein (CP) beta-subunit in motility of malaria sporozoites

Successful malaria transmission from the mosquito vector to the mammalian host depends crucially on active sporozoite motility. Sporozoite locomotion and host cell invasion are driven by the parasite's own actin/myosin motor. A unique feature of this motor machinery is the presence of very short subpellicular actin filaments. Therefore, F-actin stabilizing proteins likely play a central role in parasite locomotion. Here, we investigated the role of the Plasmodium berghei actin capping protein (PbCP), an orthologue of the heterodimeric regulator of filament barbed end growth, by reverse genetics. Parasites containing a deletion of the CP beta-subunit developed normally during the pathogenic erythrocytic cycle. However, due to reduced ookinete motility, mutant parasites form fewer oocysts and sporozoites in the Anopheles vector. These sporozoites display a vital deficiency in forward gliding motility and fail to colonize the mosquito salivary glands, resulting in complete attenuation of life cycle progression. Together, our results show that the CP beta-subunit exerts an essential role in the insect vector before malaria transmission to the mammalian host. The vital role is restricted to fast locomotion, as displayed by Plasmodium sporozoites

EFFECT OF LOW CARBOHYDRATE / LOW FAT DIETARY INTERVENTION ON GENE EXPRESSION OF GLUT IN ABDOMINAL SUBCUTANEOUS ADIPOSE TISSUE OF TYPE 2 DIABETES PATIENTS

Type 2 diabetes mellitus (T2DM) global prevalence is increasing rapidly along with obesity marking it as a major public health problem. The causes of its epidemic are embedded in a complex interaction between genes, metabolites and external factors, such as diet. To investigate the short termed effects of a moderate low fat diet (<30% fat, 50% carbohydrate, 20% protein, 1000-1200 kcal/d) and a low-carbohydrate diet (60-70% fat, 5-10% carbohydrate, 20-30% protein, 1200-1500 kcal/d) on metabolic parameters and focusing on diet-induced regulation of glucose transporters (GLUT) in subcutaneous adipose tissue (SCAT) of recently diagnosed T2DM patients. Seventeen T2DM patients were randomly assigned to the low-carbohydrate (LC) diet or to the moderate low-fat (LF) diet. SCAT biopsies and clinical parameters were obtained at baseline and after the 3 weeks dietary intervention. Reverse transcriptase polymerase chain reaction (RT-PCR) was employed to quantify the expression of GLUT in human SCAT. Both interventions led to significant reduction of weight (LC: p=0.004, LF: p<0.000), BMI (LC: p=0.008, LF: p<0.000), LDL/HDL ratio (LC: p=0.004, LF: p=0.002), total cholesterol/HDL ratio (LC: p=0.008, LF: p=0.020) and HbA1c levels (LC: p=0.025, LF: p=0.001). Whereas LDL (p=0.001) and total cholesterol (p=0.003) levels were only significantly reduced after the LF diet, waist-to-hip ratio (WHR) (p=0.013) and triglyceride (TAG) levels (p=0.013) were significantly reduced in the LC group only. After the LF diet, GLUT3 (1.19 ±0.6 to 1.78 ±0.5, p=0.019), mRNA levels increased significantly and, on the contrary, GLUT5 (1.65 ±1.5 to 0.58 ±0.44, p=0.045) mRNA levels showed a significant reduction. No significant differences were observed between diet groups after 3 weeks of diet. This short-term dietary intervention separates the improvements on WHR, TAG, total cholesterol and LDL from dietary composition-related effects. Furthermore, moderate low-fat, calorie-restricted diet may significantly upregulate GLUT3 expression and down-regulate GLUT5 expression in SCAT of T2DM patients. However, future studies on its influence on GLUT transports are needed

Elevational patterns of Polylepis tree height (Rosaceae) in the high Andes of Peru: role of human impact and climatic conditions

We studied tree height in stands of high-Andean Polylepis forests in two cordilleras near Cuzco (Peru) with respect to variations in human impact and climatic conditions, and compared air and soil temperatures between qualitatively defined dry and humid slopes. We studied 46 forest plots of 100 m(2) of five Polylepis species at 3560-4680 m. We measured diameter at breast height (dbh) and tree height in the stands (1229 trees in total), as well as air and soil temperatures in a subset of plots. The data was analyzed combining plots of given species from different sites at the same elevation (±100 m). There was no elevational decrease of mean maximum tree height across the entire data set. On humid slopes, tree height decreased continuously with elevation, whereas on dry slopes it peaked at middle elevations. With mean maximum tree heights of 9 m at 4530 m on the humid slopes and of 13 m at 4650 m on the dry slopes, we here document the tallest high-elevation forests found so far worldwide. These highest stands grow under cold mean growing season air temperatures (3.6 and 3.8°C on humid vs. dry slopes) and mean growing season soil temperatures (5.1 vs. 4.6°C). Mean annual air and soil temperature both decreased with elevation. Dry slopes had higher mean and maximum growing season air temperatures than humid slopes. Mean annual soil temperatures did not significantly differ and mean annual air temperatures only slightly differed between slopes. However, maximum air temperatures differed on average by 6.6 K between dry and humid slopes. This suggests that the differences in tree height between the two slopes are most likely due to differences in solar radiation as reflected by maximum air temperatures. Our study furthermore provides evidence that alpine Polylepis treelines grow under lower temperature conditions than global high-elevation treelines on average, suggesting that Polylepis species may have evolved special physiological adaptations to low temperatures