Sponge-derived fatty acids inhibit biofilm formation of MRSA and MSSA by down-regulating biofilm-related genes specific to each pathogen

AIM

A promising approach for the development of next generation antimicrobials is to shift their target from causing bacterial death to inhibiting virulence. Marine sponges are an excellent potential source of bioactive anti-virulence molecules (AVM). We screened fractions prepared from 26 samples of Irish coastal sponges for anti-biofilm activity against clinically relevant pathogens.

METHODS AND RESULTS

Fifteen fractions from eight sponge species inhibited biofilm of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA) and/or Listeria monocytogenes without causing growth inhibition. GC-MS analyses of Mycale contarenii fractions revealed the presence of myristic acid and oleic acid. These fatty acids repressed transcription of the fibronectin-binding protein fnbA and fnbB genes and the polysaccharide intercellular adhesin icaADBC operon, required for MRSA and MSSA biofilm formation, respectively.

CONCLUSIONS

This study illustrates the potential of AVM from Irish coastal sponges to specifically target bacterial virulence phenotypes, in this case repression of biofilm formation via decreased transcription of biofilm-associated genes in MSSA and MRSA.

Faeces' odours attract gregarious locust hoppers

Collective motion is one of the most impressive common features of gregarious locusts: once formed, bands and swarms get moving for long distances. It was shown that visual perception of neighbours plays a key role in maintaining marching behaviour at a local scale. But at a larger scale, mechanisms underlying band cohesion are less understood. It was shown in several field studies that individuals separated from the band were able to get back to the group, even after being separated since a night. In this context, faeces' odours could be a possible indicator of the recent passage of a group. In this study, we tested if nymphs are attracted by faeces' odours and if this effect is modulated by the age of the faeces. To this end, we conducted individual olfactometric behavioural assays of 3^rd instar hoppers of desert locust, Schistocerca gregaria, exposed to odours of 1 h-old and 24 h-old faeces. We also used Gas Chromatography-Mass Spectrometry (GC-MS) to identify odours' volatile organic compounds from faeces. The results of behavioural assays indicated a strong attractive effect of faeces, with no preference for one of the two faecal age classes. Nymphs spent significantly more time in the side of the olfactometer where the faeces' odours came from, and 72.7% of tested individuals chose this side first. We filtered and annotated 11 volatile organic compounds present in both fresh and old faeces in GC-MS analyses, including guaiacol and phenol, which are known to cause an aggregative effect on desert locusts. As the attractive effect lasted over 24 h, band's faeces could still have an attractive effect when individuals are separated from the band since one day. In this situation, latecomers individuals would be able to get back to the group by following the traces of their predecessors.

Chemical detection triggers honey bee defense against a destructive parasitic threat

Invasive species events related to globalization are increasing, resulting in parasitic outbreaks. Understanding of host defense mechanisms is needed to predict and mitigate against the consequences of parasite invasion. Using the honey bee Apis mellifera and the mite Varroa destructor, as a host-parasite model, we provide a comprehensive study of a mechanism of parasite detection that triggers a behavioral defense associated with social immunity. Six Varroa-parasitization-specific (VPS) compounds are identified that (1) trigger Varroa-sensitive hygiene (VSH, bees' key defense against Varroa sp.), (2) enable the selective recognition of a parasitized brood and (3) induce responses that mimic intrinsic VSH activity in bee colonies. We also show that individuals engaged in VSH exhibit a unique ability to discriminate VPS compounds from healthy brood signals. These findings enhance our understanding of a critical mechanism of host defense against parasites, and have the potential to apply the integration of pest management in the beekeeping sector.

Chemical Profiles of Integumentary and Glandular Substrates in Australian Sea Lion Pups (Neophoca cinerea)

Recognition of individuals or classes of individuals plays an important role in the communication systems of many mammals. The ability of otariid (i.e., fur seal and sea lion) females to locate and identify their offspring in colonies after returning from regular foraging trips is essential to successful pup rearing. It has been shown that olfaction is used to confirm the identity of the pup by the mother when they reunite, yet the processes by which this chemical recognition occurs remain unclear. Using gas chromatography-mass spectrometry, we examined chemical profiles of integumentary and glandular secretions/excretions from pre- and post-molt Australian sea lion pups (Neophoca cinerea) and compared fur and swab samples to assess data collection methods. Multivariate statistics were applied to assess differences in chemical composition between body regions and sexes. We found differences among secretions from various body regions, driven by the distinctiveness of the oral odor mixture. The fine-scale trends in pre- and post-molt pups seem to differ due to changes in the behavior of pups and consequent decrease in the transfer of compounds among adjacent body regions in older pups. Volatile compounds from exocrine substrates were not distinct for different sexes. We also show that swab samples provide better data for exploring social olfaction than fur samples for this species. Obtaining fundamental chemical information, in this case chemical profiles of animals, and discerning differences in chemical composition is an important step toward fully exploring the intricacies of mother-offspring olfactory recognition and its underlying processes.

Acibenzolar-S-Methyl Reprograms Apple Transcriptome Toward Resistance to Rosy Apple Aphid

Acibenzolar-S-methyl (ASM) is a chemical compound, which is able to induce resistance in several model and non-model plants, but the end-players of this induced defense remain ill-defined. Here, we test the hypothesis that treatment with ASM can protect apple (Malus × domestica) against the rosy apple aphid (Dysaphis plantaginea) and investigate the defense molecules potentially involved in resistance. We measured aphid life traits and performed behavioral assays to study the effect of ASM on plant resistance against the aphid, and then combined transcriptomic, bioinformatics, metabolic and biochemical analyses to identify the plant compounds involved in resistance. Plants treated with ASM negatively affected several life traits of the aphid and modified its feeding and host seeking behaviors. ASM treatment elicited up-regulation of terpene synthase genes in apple and led to the emission of (E,E)-α-farnesene, a sesquiterpene that was repellent to the aphid. Several genes encoding amaranthin-like lectins were also strongly up-regulated upon treatment and the corresponding proteins accumulated in leaves, petioles and stems. Our results link the production of specific apple proteins and metabolites to the antibiosis and antixenosis effects observed against Dysaphis plantaginea, providing insight into the mechanisms underlying ASM-induced herbivore resistance.

Lung nodule in French Guiana in a immunocompetent patient

We report the case of an immunocompetent French soldier stationed in French Guiana, who developed symptomatic pulmonary histoplasmosis.

Malaria Hyperendemicity and Risk for Artemisinin Resistance among Illegal Gold Miners, French Guiana

To assess the prevalence of malaria among illegal gold miners in the French Guiana rainforest, we screened 205 miners during May-June 2014. Malaria prevalence was 48.3%; 48.5% of cases were asymptomatic. Patients reported self-medication with artemisinin-based combination therapy. Risk for emergence and spread of artemisinin resistance among gold miners in the rainforest is high.

Colour-scent associations in a tropical orchid: three colours but two odours

Colour and scent are the major pollinator attractants to flowers, and their production may be linked by shared biosynthetic pathways. Species with polymorphic floral traits are particularly relevant to study the joint evolution of floral traits. We used in this study the tropical orchid Calanthe sylvatica from Réunion Island. Three distinct colour varieties are observed, presenting lilac, white or purple flowers, and named respectively C. sylvaticavar.lilacina (hereafter referred as var. lilacina), C. sylvaticavar. alba (var. alba) and C. sylvatica var. purpurea (var. purpurea). We investigated the composition of the floral scent produced by these colour varieties using the non-invasive SPME technique in the wild. Scent emissions are dominated by aromatic compounds. Nevertheless, the presence of the terpenoid (E)-4,8-dimethylnona-1,3,7-triène (DMNT) is diagnostic of var. purpurea, with the volatile organic compounds (VOC) produced by some individuals containing up to 60% of DMNT. We evidence specific colour-scent associations in C. sylvatica, with two distinct scent profiles in the three colour varieties: the lilacina-like profile containing no or very little DMNT (<2%) and the purpurea-like profile containing DMNT (>2%). Calanthe sylvatica var. alba individuals group with one or the other scent profile independently of their population of origin. We suggest that white-flowered individuals have evolved at least twice, once from var. lilacina and at least once from var. purpurea after the colonisation of la Réunion. White-flowered individuals may have been favoured by the particular pollinator fauna characterising the island. These flowering varieties of C. sylvatica, which display three colours but two scents profiles prove that colour is not always a good indicator of odour and that colour-scent associations may be complex, depending on pollination ecology of the populations concerned.

Body Composition in Diabetic Subjects with Chronic Kidney Disease: Interest of Bio-Impedance Analysis, and Anthropometry

BACKGROUND/AIMS

Lean body mass (LBM) is reduced in uremia, but this has not been reported in diabetic nephropathy.

SUBJECTS AND METHODS

We compared predicted % LBM to DEXA measurements in 10 non-diabetic uremic, 10 non-uremic diabetic and 10 uremic diabetic subjects matched for age, gender and BMI. We also measured % LBM by anthropometry, bio-impedance analysis (BIA) and compared them with DEXA in 49 diabetic subjects with a wide range of renal failure. The results were compared and a Bland & Altman procedure was performed. Associations between glomerular filtration rate (GFR) and % LBM were tested.

RESULTS

In matched groups, predicted % LBM values were overestimated in non-diabetic uremic subjects, and underestimated in non-uremic diabetic subjects. In uremic diabetic subjects, the error was intermediary. As compared to DEXA (% LBM: 69.0 +/- 7.1%), measurement of % LBM by anthropometry (71.4 +/- 8.0%, p < 0.05) and BIA (67.2 +/- 7.6%, p < 0.05) were biased in the 49 diabetic subjects. The mean of anthropometric and BIA (Ant+BIA) were similar to DEXA results (69.3 +/- 6.8%, p = 0.64), with best correlation coefficients and Bland & Altman plots. GFR was correlated to % LBM assessed by DEXA, BIA and Ant+BIA.

CONCLUSION

In diabetic subjects with chronic kidney disease, LBM should be measured, rather than predicted. A good evaluation is possible, even without DEXA.