Propionic acid side chain hydrogen bonding in the malaria pigment beta-hematin

Malaria pigment, or beta-hematin, the insoluble heme detoxification product resulting from the intraerythrocitic digestion of hemoglobin by young malaria trophozoites has been structurally characterized by X-ray powder diffraction and shown to contain chains of propionic acid linked dimers. Although there is considerable spectroscopic evidence for a monodentate propionate-iron interaction in this crystalline material, the spectroscopic characterization of the propionic acid dimer is limited. Herein we demonstrate the presence of the propionic acid dimer unit by H/D isotope substitution in carboxylic acid dimer. In the Raman spectrum of the deuterium substituted compound there is a circa 12 cm(-1) shift, H: 1629 cm(-1) vs. D: 1617 cm(-1) in the symmetric ring breathing mode for the propionic acid dimer. On the other hand, the IR active asymmetric stretch has a very small shift, <3 cm(-1), upon deuteration. These, and other vibrational data, are consistent with the presence of a planar carboxylic acid dimer in the structure of beta-hematin.     

Functional analysis of the venom of mealybug parasitoid Aenasius bambawalei (Hymenoptera: Encyrtidae)

Aenasius bambawalei (Hymenoptera: Encyrtidae) is a koinobiont nymphal endoparasitoid of cotton mealybug, Phenacoccus solenopsis (Hemiptera: Pseudocccidae). Functional analysis of the venom of the wasp was performed by artificial microinjections of both crude and treated venom (heat and proteinase) of the wasp containing 0.3 and 0.5 μl in non-parasitized and synchronized adult hosts (mealybugs) and the mortality data were recorded 24, 48, 72 and 96 hours post injecton while mealybugs receiving saline injections were acted as control. The main effects for artificially envenomated mealybugs were observed on their mortality and survival. The biological activity of crude venom was also evaluated by heat and protease treatment. Here, we demonstrate that maximum mortality (82 ± 2.0%) was achieved by microinjections containing higher volume (0.5 μl) of crude venom while lower mortality (68 ± 4.0%) was achieved with lower volume of venom (0.3 μl). On the other hand, heat and proteinase K treated venom did not show any significant effect on mortality of the host insect. Our findings suggest that bioactive components of the crude venom are proteins which lost their activity upon heat and protease treatment. This basic information regarding the functional role of the venom of A. bambawalei serves as a starting point for comprehensive analysis of the role of the venom of the parasitoid on the regulation processes in its host.     

Effect of exposure to 50 Hz magnetic field with or without insulin on blood–brain barrier permeability in streptozotocin‐induced diabetic rats

We investigated the effect of long‐term exposure to modulation magnetic field (MF), insulin, and their combination on blood–brain barrier (BBB) permeability in a diabetic rat model. Fifty‐three rats were randomly assigned to one of six groups: sham, exposed to no MF; MF, exposed to MF; diabetes mellitus (DM), DM induced with streptozotocin (STZ); DM plus MF (DMMF); DM plus insulin therapy (DMI); and DM plus insulin therapy plus MF (DMIMF). All the rats underwent Evans blue (EB) measurement to evaluate the BBB 30 days after the beginning of experiments. The rats in MF, DMMF, and DMIMF groups were exposed to MF (B = 5 mT) for 165 min every day for 30 days. Mean arterial blood pressure (MABP), body mass, and serum glucose level of the study rats were recorded. The extravasation of brain EB of the MF, DM, DMMF, DMI, and DMIMF groups was higher than that of the sham group and the extravasation of right hemisphere of the DMIMF group was highest (P < 0.05). The post‐procedure body mass of the sham and MF groups were significantly higher than those of the DM and DMMF groups (P < 0.05). In the DM, DMMF, DMI, and DMIMF groups, the baseline glucose was significantly lower than the post‐procedure glucose (P < 0.05). DM and MF increase BBB permeability; in combination, they cause more increase in BBB permeability, and insulin decreases their effect on BBB. Improved glucose metabolism may prevent body mass loss and the hypoglycemic effect of MF. DM increases MABP but MF causes no additional effect. Bioelectromagnetics 31:262–269, 2010. © 2009 Wiley‐Liss, Inc.     

Significance of serum trace element status in patients with rheumatic heart disease: a prospective study

It is known that certain trace elements can affect various heart diseases. In this study, we aimed to evaluate the changes in concentrations of certain serum trace elements in patients with chronic rheumatic heart disease (RHD). Serum analysis of selenium (Se), zinc (Zn), and copper (Cu) trace elements was assayed by atomic absorption spectrophotometry. RHD patients had significantly lower serum concentrations of Se and Zn than control subjects (p < 0.05 and p < 0.001, respectively). However, the serum Cu concentration was significantly higher in RHD patients than in controls (1.93 +/- 0.59 microg/L vs 1.06 +/- 0.29 microg/L; p < 0.001). Similarly, the Cu/Zn ratio in RHD patients was higher than in control subjects (4.70 +/- 0.92 vs 1.68 +/- 0.45; p < 0.001). Additionally, no significant correlation was found among these trace element concentrations and the functional capacity classes (p > 0.05). RHD patients had decreased serum Se and Zn element concentrations and increased serum Cu element concentration. We suggest that Se and Zn deficiency might be contributory factors in the development of rheumatic heart disease, and a high Cu concentration and a high Cu/Zn ratio might reflect an ongoing inflammatory process in this disease.     

Structural and morphological characterization of hemozoin produced by Schistosoma mansoni and Rhodnius prolixus

Hemozoin (Hz) is a heme crystal produced upon the digestion of hemoglobin (Hb) by blood-feeding organisms as a main mechanism of heme disposal. The structure of Hz consists of heme dimers bound by reciprocal iron-carboxylate interactions and stabilized by hydrogen bonds. We have recently described heme crystals in the blood fluke, Schistosoma mansoni, and in the kissing bug, Rhodnius prolixus. Here, we characterized the structures and morphologies of the heme crystals from those two organisms and compared them to synthetic β-hematin (βH). Synchrotron radiation X-ray powder diffraction showed that all heme crystals share the same unit cell and structure. The heme crystals isolated from S. mansoni and R. prolixus consisted of very regular units assembled in multicrystalline spherical structures exhibiting remarkably distinct surface morphologies compared to βH. In both organisms, Hz formation occurs inside lipid droplet-like particles or in close association to phospholipid membranes. These results show, for the first time, the structural and morphological characterization of natural Hz samples obtained from these two blood-feeding organisms. Moreover, Hz formation occurring in close association to a hydrophobic environment seems to be a common trend for these organisms and may be crucial to produce very regular shaped phases, allowing the formation of multicrystalline assemblies in the guts of S. mansoni and R. prolixus.     

Religious Affiliation Modulates Weekly Cycles of Cropland Burning in Sub-Saharan Africa

Vegetation burning is a common land management practice in Africa, where fire is used for hunting, livestock husbandry, pest control, food gathering, cropland fertilization, and wildfire prevention. Given such strong anthropogenic control of fire, we tested the hypotheses that fire activity displays weekly cycles, and that the week day with the fewest fires depends on regionally predominant religious affiliation. We also analyzed the effect of land use (anthrome) on weekly fire cycle significance. Fire density (fire counts.km^-2) observed per week day in each region was modeled using a negative binomial regression model, with fire counts as response variable, region area as offset and a structured random effect to account for spatial dependence. Anthrome (settled, cropland, natural, rangeland), religion (Christian, Muslim, mixed) week day, and their 2-way and 3-way interactions were used as independent variables. Models were also built separately for each anthrome, relating regional fire density with week day and religious affiliation. Analysis revealed a significant interaction between religion and week day, i.e. regions with different religious affiliation (Christian, Muslim) display distinct weekly cycles of burning. However, the religion vs. week day interaction only is significant for croplands, i.e. fire activity in African croplands is significantly lower on Sunday in Christian regions and on Friday in Muslim regions. Magnitude of fire activity does not differ significantly among week days in rangelands and in natural areas, where fire use is under less strict control than in croplands. These findings can contribute towards improved specification of ignition patterns in regional/global vegetation fire models, and may lead to more accurate meteorological and chemical weather forecasting.     

Molecular genetic diversity and association mapping of morphine content and agronomic traits in Turkish opium poppy (<Emphasis Type="Italic">Papaver somniferum</Emphasis>) germplasm

As the sole plant source of many potent alkaloids, opium poppy (Papaver somniferum L.) is an important medicinal crop. Nevertheless, few studies have characterized opium poppy germplasm with crop-specific molecular markers. Because Turkey is a diversity center for opium poppy, Turkish germplasm is a valuable genetic resource for association mapping studies aimed at identifying QTLs controlling morphine content and agronomic traits. In this study, the morphological diversity and molecular diversity of 103 Turkish opium poppy landraces and 15 cultivars were analyzed. Potentially useful morphological variation was observed for morphine content, plant height, and capsule index. However, the landraces exhibited limited breeding potential for stigma number, and seed and straw yields. Both morphological and molecular analyses showed distinct clustering of cultivars and landraces. In addition, a total of 164 SSR and 367 AFLP polymorphic loci were applied to an opium poppy association mapping panel composed of 95 opium poppy landraces which were grown for two seasons. One SSR and three AFLP loci were found to be significantly associated with morphine content (P < 0.01 and LD value (r ²) = 0.10–0.32), and six SSR and 14 AFLP loci were significantly associated with five agronomic traits (plant height, stigma number, capsule index, and seed and straw yields) (P < 0.01 and LD value (r ²) = 0.08–0.35). This is the first report of association mapping in this crop. The identified markers provide initial information for marker-assisted selection of important traits in opium poppy breeding.     

Local induction of acetylcholine receptor clustering in myotube cultures using microfluidic application of agrin

During neuromuscular synaptogenesis, the exchange of spatially localized signals between nerve and muscle initiates the coordinated focal accumulation of the acetylcholine (ACh) release machinery and the ACh receptors (AChRs). One of the key first steps is the release of the proteoglycan agrin focalized at the axon tip, which induces the clustering of AChRs on the postsynaptic membrane at the neuromuscular junction. The lack of a suitable method for focal application of agrin in myotube cultures has limited the majority of in vitro studies to the application of agrin baths. We used a microfluidic device and surface microengineering to focally stimulate muscle cells with agrin at a small portion of their membrane and at a time and position chosen by the user. The device is used to verify the hypothesis that focal application of agrin to the muscle cell membrane induces local aggregation of AChRs in differentiated C2C12 myotubes.