Synthesis,characterization, and cellular localization of a fluorescent probe of the antimalarial 8-aminoquinoline primaquine

Primaquine (PQ) is the only commercially available drug that clears dormant liver stages of malaria and blocks transmission to mosquito vectors. Although an old drug, much remains to be known about the mechanism(s) of action. Herein we develop a fluorescent tagged PQ to discover cellular localization in the human malaria parasite, Plasmodium falciparum. Successful synthesis and characterization of a primaquine-coumarin fluorescent probe (PQCP) demonstrated potency equivalent to the parent drug and the probe was not cytotoxic to HepG2 carcinoma cells. Cellular localization was found primarily in the cytosol of the asexual erythrocytic and gametocyte stages of parasite development.     

Participant Profiling and Pattern of Crop-Foraging in Chacma Baboons (<Emphasis Type="Italic">Papio hamadryas ursinus</Emphasis>) in Zimbabwe: Why Does Investigating Age–Sex Classes Matter?

Transformation and loss of natural habitat to urbanization and agriculture provide new opportunities for primates to feed on anthropogenic food sources. Currently, mitigation strategies fail to target the individuals responsible for initiating and maintaining this behavior. As primates mainly forage on crops in groups, we investigate the crop-foraging behavior of a group of 40 chacma baboons in Zimbabwe from the perspective of collective movements, i.e., when a group of animals move together in the same direction, thus resulting in a change of location. We collected data on 110 crop-foraging events during 35 days in March–April 2014. We recorded baboon movement and behavior with a camcorder and obtained further information through video analysis. Most crop-foraging events involved less than 20% of the troop and lasted less than 3 min. Although crop-foraging parties were composed of all age–sex classes, adult females and particularly adult males initiated most crop-foraging events and made direct movements (without stopping on the road) more often than nonadult participants. Baboons made up to five successive attempts to crop forage in a single crop-foraging event. Neither the number of participants nor the success of the crop-foraging events increased over the successive attempts. Finally, crop-foraging events were more successful and more frequent in unguarded areas than in guarded areas. These results suggest that group members are highly synchronized and that crop-foraging is based on a collective decision such as classical foraging movements. In addition, the short duration of the crop-foraging events might prevent detection of baboons by farmers. The more frequent initiation of crop-foraging by adults compared to nonadults might be explained by greater energetic needs or a greater tendency of adults to take risks. These preliminary data can help inform long-term strategies for farmers to reduce crop losses to baboons, as guarding helps reduce damage but does not prevent it.     

Cyclodextrin-surfactant complex: a new route in DNA decompaction

In the present work, we show a new approach for decompaction of DNA-cationic surfactant complexes, e.g., lipoplexes, by using beta-cyclodextrin (beta-CD). The DNA decompaction was achieved by dissolving the surfactant aggregates in the complex by making use of the high affinity between the beta-CD and the free surfactant in solution. The results from fluorescence microscopy and adiabatic compressibility measurements indicate that coils and globules do not coexist. The reported procedure using beta-CD is an efficient way to decompact DNA surfactant complexes because the association constant of surfactants with beta-CD is large. The surfactant's interaction with beta-CD is specific and the nonspecific interaction between beta-CD and biological interfaces is small.     

Role of rhizosphere mechanisms in Cd uptake by various wheat cultivars

In each wheat type, cultivars have different propensities to accumulate Cd in their grains, likely depending on Cd uptake by roots and/or Cd distribution in the plant. This study investigates the processes in the root–soil interface and their role in high or low grain Cd accumulation. Twenty-four cultivars of spring bread, winter bread, durum, and spelt wheat with different grain Cd accumulation levels were investigated regarding removal of Cd from soil, pH, Cd and organic acids in root exudates, and cation-exchange capacity of roots (rootCEC). In addition, we investigated ¹⁰⁹Cd uptake from a nutrient solution resembling soil solution. The removal of Cd from the rhizosphere soil increased, likely due to increased rootCEC with increased grain Cd accumulation propensity, except in spring bread wheat. The ¹⁰⁹Cd uptake from solution did not differ between high and low grain Cd accumulators. If the soil Cd concentration was elevated, rootCEC increased, as did pH, and succinic acid levels in the exudates, while lactic and citric acid levels in root exudates decreased. This work indicates that high grain Cd accumulators take up more Cd from soil than do low accumulators. But not by a different capacity to take up Cd from soil solution. The higher rootCEC in high accumulating cultivars may influence the release of Cd from the soil particles.     

Longitudinal Study of Escherichia coli O157:H7 in a Beef Cattle Feedlot and Role of High-Level Shedders in Hide Contamination

The objectives of the study described here were (i) to investigate the dynamics of Escherichia coli O157:H7 fecal and hide prevalence over a 9-month period in a feedlot setting and (ii) to determine how animals shedding E. coli O157:H7 at high levels affect the prevalence and levels of E. coli O157:H7 on the hides of other animals in the same pen. Cattle (n = 319) were distributed in 10 adjacent pens, and fecal and hide levels of E. coli O157:H7 were monitored. When the fecal pen prevalence exceeded 20%, the hide pen prevalence was usually (25 of 27 pens) greater than 80%. Sixteen of 19 (84.2%) supershedder (>10⁴ CFU/g) pens had a fecal prevalence greater than 20%. Significant associations with hide and high-level hide (≥40 CFU/100 cm²) contamination were identified for (i) a fecal prevalence greater than 20%, (ii) the presence of one or more high-density shedders (≥200 CFU/g) in a pen, and (iii) the presence of one or more supershedders in a pen. The results presented here suggest that the E. coli O157:H7 fecal prevalence should be reduced below 20% and the levels of shedding should be kept below 200 CFU/g to minimize the contamination of cattle hides. Also, large and unpredictable fluctuations within and between pens in both fecal and hide prevalence of E. coli O157:H7 were detected and should be used as a guide when preharvest studies, particularly preharvest intervention studies, are designed.It is now well established that at the time of harvest, hides are the major source of Escherichia coli O157:H7 contamination on beef carcasses (1, 4, 22). Thus, reducing the levels of food-borne pathogens on cattle hides has been the focus of many pre- and postharvest research efforts. For postharvest applications, hide interventions (i.e., washing of hide-on carcasses with various antimicrobial agents) are direct approaches and have been shown to be efficacious for reducing hide and carcass contamination rates (2, 4, 5, 22).In the area of preharvest research, several approaches have been taken to reduce the prevalence of E. coli O157:H7 in feces of cattle presented for slaughter. These approaches include, among others, feeding cattle probiotics (dietary administration of beneficial bacteria to compete with E. coli O157:H7), vaccination, and bacteriophage treatment (8, 24, 30). These intervention approaches are indirect. By reducing the fecal pathogen load, the pathogen prevalence and the level on hides are reduced through lower cross-contamination at the feedlot, and subsequently, carcass contamination rates decrease. While the effectiveness of preharvest interventions varies, no preharvest intervention is 100% effective in reducing the fecal prevalence of E. coli O157:H7. It is not known what level of pathogen reduction in feces would be necessary to significantly reduce hide and carcass contamination during processing. Key pieces of information needed to address this question are the number of shedding cattle in a pen needed to contaminate the hides of most of the cattle in the same pen and at what level the shedding cattle are contaminated.Aside from the number of cattle shedding a pathogen, the concentration of the pathogen in feces plays a pivotal role in spreading the pathogen between animals. Recently, cattle shedding E. coli O157:H7 at levels of >10⁴ CFU/g (“supershedders”) have been associated with high rates of transmission of the pathogen between cohort animals (18, 23). Matthews et al. reported that 20% of the E. coli O157:H7 infections in cattle on Scottish farms were responsible for 80% of the transmission of the organism between animals (18). Another study reported similar findings; 9% of the animals shedding E. coli O157:H7 produced over 96% of the total E. coli O157:H7 fecal load for the group (23). While a number of studies have indicated the importance of supershedders in fecal transmission dynamics, there is a general lack of information concerning the effects of high shedding rates on hide prevalence and load. Accordingly, the objectives of this study were (i) to investigate the dynamics of E. coli O157:H7 prevalence and levels in feces and on hides of feedlot cattle over time and (ii) to determine how pathogen prevalence and levels on hides in a pen are affected by individuals shedding E. coli O157:H7 at high levels.In the analysis presented here, fecal shedding was analyzed using the following three categories based on the level of E. coli O157:H7 being shed: shedding positive (presumed concentration, ≥1 CFU/g), high-density shedder (≥200 CFU/g), and supershedder (≥10⁴ CFU/g). Several definitions of E. coli O157:H7 supershedders have been offered previously. One-time shedding levels of >10³ or >10⁴ CFU/g have been used in multiple studies (17, 23, 24), while other groups have required persistent colonization of the rectoanal junction, as well as high cell counts, for an animal to qualify as a supershedder (10). Recently, Chase-Topping et al. (9) reviewed the requirements for supershedder status and provided a working definition: an animal that excretes >10⁴ CFU/g. In doing this, Chase-Topping et al. noted the high stringency of this definition and acknowledged that with such a definition some supershedders will be missed if they are sampled at times other than peak shedding times (9). In the current study, this was a concern. In an attempt to investigate the link between high-shedding-level animals and hide contamination, greater leeway was needed in the classification. When it is sampled on a monthly basis, an animal shedding at high levels can have a large impact on the hide status of pen cohorts between sampling intervals but not be shedding at peak levels on the day of sample collection. Hence, the categories described above were selected to analyze the relationship between fecal shedding and hide contamination.     

Modeling the Time Evolution of the Nanoparticle-Protein Corona in a Body Fluid

Background

Nanoparticles in contact with biological fluids interact with proteins and other biomolecules, thus forming a dynamic corona whose composition varies over time due to continuous protein association and dissociation events. Eventually equilibrium is reached, at which point the continued exchange will not affect the composition of the corona.

Results

We developed a simple and effective dynamic model of the nanoparticle protein corona in a body fluid, namely human plasma. The model predicts the time evolution and equilibrium composition of the corona based on affinities, stoichiometries and rate constants. An application to the interaction of human serum albumin, high density lipoprotein (HDL) and fibrinogen with 70 nm N-iso-propylacrylamide/N-tert-butylacrylamide copolymer nanoparticles is presented, including novel experimental data for HDL.

Conclusions

The simple model presented here can easily be modified to mimic the interaction of the nanoparticle protein corona with a novel biological fluid or compartment once new data will be available, thus opening novel applications in nanotoxicity and nanomedicine.     

Small worms, big appetites: ratios of different functional morphs in relation to interspecific competition in trematode parasites

Animals living in colonies or collectives composed of highly-related individuals often produce morphs that are physically and behaviourally specialised to perform specific tasks. Because such morphs are often sterile, their production represents a fitness cost for the colony and there should be an optimal ratio of the numbers of sterile specialists and reproductive members that may be adjustable to environmental conditions. Trematode parasites undergo asexual multiplication within their snail intermediate host, resulting in large numbers of clonal stages known as rediae or sporocysts, depending on the trematode species. In areas with high prevalences of infection, the host can be infected by multiple species, which can lead to intense competition for limited resources. Here, we describe the existence of specialised ‘mini-rediae’ in the trematode Philophthalmus sp. that are morphologically and functionally specialised for interspecific competition. Mini-rediae were observed feeding on the sporocysts of a co-occurring trematode species - Maritrema novaezealandensis. In addition, in larger snails - which are less likely to have M. novaezealandensis infections - Philophthalmus sp. produces relatively fewer mini-rediae than expected. Our findings support results from a prior study which demonstrated the existence of morphs that perform specialised functions in antagonistic interspecific interactions in trematodes, and additionally shows that the number of these morphs in each host is associated with the likelihood of encountering other species within the same host. Trematodes may thus provide interesting models for studying morphological specialisation in colonial organisms.