Overview of the Oldest Existing Set of Substrate-optimized Anaerobic Processes: Digestive Tracts

Over millions of years, living organisms have explored and optimized the digestion of a wide variety of substrates. Engineers who develop anaerobic digestion processes for waste treatment and energy production can learn much from this accumulated ‘experience’. The aim of this work is a survey based on the comparison of 190 digestive tracts (vertebrate and insect) considered as ‘reactors’ and their anaerobic processes. Within a digestive tract, each organ is modeled as a type of reactor (continuous stirred-tank, such reactors in series, plug-flow or batch) associated with chemical aspects such as pH or enzymes. Based on this analysis, each complete digestion process has been rebuilt and classified in accordance with basic structures which take into account the relative size of the different reactors. The results show that all animal digestive structures can be grouped within four basic types. Size and/or position in the structure of the different reactors (pre/post treatment and anaerobic microbial digestion) are closely correlated to the degradability of the feed (substrate). Major common features are: (i) grinding, (ii) an extreme pH compartment, and (iii) correlation between the size of the microbial compartment and the degradability of the feed. Thus, shared answers found by animals during their evolution can be a source of inspiration for engineers in designing optimal anaerobic processes.     

Mus in Morocco: a Quaternary sequence of intraspecific evolution

North Africa is an intricate biogeographical region at the crossroads of immigration waves from tropical Africa and Asia. Species confined between various barriers (Atlas Mountains, arid environments such as the Sahara in the south, water masses such as the Mediterranean Sea in the north, and the Atlantic Ocean in the west) were generally forced to adapt locally to environmental changes instead of tracking their habitat by shifting their distribution area. The present study aims at providing first insight into the evolution of the genus Mus, and more specifically of the western Mediterranean species Mus spretus in this area. The study relies on the abundant Late Pleistocene and Middle Holocene fossil assemblage from the El Harhoura 2 cave (Rabat‐Témara, Morocco). This exceptional record was studied using geometric morphometrics applied to first upper and lower molars, constituting the most informative and best preserved fossil remains for such small rodents. Two main issues were addressed. (1) Geometric morphometrics was used to clarify taxonomic status and phylogenetic relationships among fossil and modern species in this area. Morphometric analysis revealed good discrimination of most modern and fossil species but failed to document intermediate forms tracing anagenetic evolution. Not mutually exclusive, the occurrence of complex processes of morphological evolution in this genus such as parallel evolution and the action of stabilizing selection may make it difficult to translate patterns of morphological evolution into phylogenetic conclusions. (2) The record was shown to document a sequence of intraspecific evolution of M. spretus. The morphology of the molars through the fossil record of El Harhoura 2 was surprisingly stable despite extensive modern variation. The limited temporal variation largely failed to correlate to palaeoenvironmental proxies. The mouse fossil record at El Harhoura 2 thus presents an intriguing case of morphological stasis despite extensive environmental changes. This long‐term stability may have been recently perturbed by anthropogenic factors including landscape changes and introduction of various competitors and predators, leading to a size reduction. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 599–621.     

New insights into the ear region anatomy and cranial blood supply of advanced stem Strepsirhini: Evidence from three primate petrosals from the Eocene of Chambi,Tunisia

We report the discovery of three isolated primate petrosal fragments from the fossiliferous locality of Chambi (Tunisia), a primate-bearing locality dating from the late early to the early middle Eocene. These fossils display a suite of anatomical characteristics otherwise found only in strepsirhines, and as such might be attributed either to Djebelemur or/and cf. Algeripithecus, the two diminutive stem strepsirhine primates recorded from this locality. Although damaged, the petrosals provide substantial information regarding the ear anatomy of these advanced stem strepsirhines (or pre-tooth-combed primates), notably the patterns of the pathway of the arterial blood supply. Using μCT-scanning techniques and digital segmentation of the structures, we show that the transpromontorial and stapedial branches of the internal carotid artery (ICA) were present (presence of bony tubes), but seemingly too small to supply enough blood to the cranium alone. This suggests that the ICA was not the main cranial blood supply in stem strepsirhines, but that the pharyngeal or vertebral artery primitively ensured a great part of this role instead, an arterial pattern that is reminiscent of modern cheirogaleid, lepilemurid lemuriforms and lorisiforms. This could explain parallel loss of the ICA functionality among these families. Specific measurements made on the cochlea indicate that the small strepsirhine primate(s) from Chambi was (were) highly sensitive to high frequencies and poorly sensitive to low frequencies. Finally, variance from orthogonality of the plane of the semicircular canals (SCs) calculated on one petrosal (CBI-1-569) suggests that Djebelemur or cf. Algeripithecus likely moved (at least its head) in a way similar to that of modern mouse lemurs.     

Monitoring resistance to Bacillus thuringiensis subsp. israelensis in the field by performing bioassays with each Cry toxin separately

Bacillus thuringiensis subsp. israelensis (Bti) is increasingly used worldwide for mosquito control and is the only larvicide used in the French Rhône-Alpes region since decades. The artificial selection of mosquitoes with field-persistent Bti collected in breeding sites from this region led to a moderate level of resistance to Bti, but to relatively high levels of resistance to individual Bti Cry toxins. Based on this observation, we developed a bioassay procedure using each Bti Cry toxin separately to detect cryptic Bti-resistance evolving in field mosquito populations. Although no resistance to Bti was detected in none of the three mosquito species tested (Aedes rusticus, Aedes sticticus and Aedes vexans), an increased tolerance to Cry4Aa (3.5-fold) and Cry11Aa toxins (8-fold) was found in one Ae. sticticus population compared to other populations of the same species, suggesting that resistance to Bti may be arising in this population. This study confirms previous works showing a lack of Bti resistance in field mosquito populations treated for decades with this bioinsecticide. It also provides a first panorama of their susceptibility status to individual Bti Cry toxins. In combination with bioassays with Bti, bioassays with separate Cry toxins allow a more sensitive monitoring of Bti-resistance in the field.     

EVOLUTIONARY INFERENCES FROM THE ANALYSIS OF EXCHANGEABILITY

Evolutionary inferences are usually based on statistical models that compare mean genotypes or phenotypes (or their frequencies) among populations. An alternative is to use the full distribution of genotypes and phenotypes to infer the “exchangeability” of individuals among populations. We illustrate this approach by using discriminant functions on principal components to classify individuals among paired lake and stream populations of threespine stickleback in each of six independent watersheds. Classification based on neutral and nonneutral microsatellite markers was highest to the population of origin and next highest to populations in the same watershed. These patterns are consistent with the influence of historical contingency (separate colonization of each watershed) and subsequent gene flow (within but not between watersheds). In comparison to this low genetic exchangeability, ecological (diet) and morphological (trophic and armor traits) exchangeability was relatively high—particularly among populations from similar habitats. These patterns reflect the role of natural selection in driving parallel adaptive changes when independent populations colonize similar habitats. Importantly, however, substantial nonparallelism was also evident. Our results show that analyses based on exchangeability can confirm inferences based on statistical analyses of means or frequencies, while also refining insights into the drivers of—and constraints on—evolutionary diversification.     

Rhamnogalacturonan II structure shows variation in the side chains monosaccharide composition and methylation status within and across different plant species

A paradigm regarding rhamnogalacturonans II (RGII) is their strictly conserved structure within a given plant. We developed and employed a fast structural characterization method based on chromatography and mass spectrometry, allowing analysis of RGII side chains from microgram amounts of cell wall. We found that RGII structures are much more diverse than so far described. In chain A of wild‐type plants, up to 45% of the l –fucose is substituted by l –galactose, a state that is seemingly uncorrelated with RGII dimerization capacity. This led us to completely reinvestigate RGII structures of the Arabidopsis thaliana fucose‐deficient mutant mur1, which provided insights into RGII chain A biosynthesis, and suggested that chain A truncation, rather than l –fucose to l –galactose substitution, is responsible for the mur1 dwarf phenotype. Mass spectrometry data for chain A coupled with NMR analysis revealed a high degree of methyl esterification of its glucuronic acid, providing a plausible explanation for the puzzling RGII antibody recognition. The β–galacturonic acid of chain A exhibits up to two methyl etherifications in an organ‐specific manner. Combined with variation in the length of side chain B, this gives rise to a family of RGII structures instead of the unique structure described up to now. These findings pave the way for studies on the physiological roles of modulation of RGII composition.     

Pyridine to aniline: An exceptional biologically driven rearrangement

During the course of our study on the innovative ligand for nicotinic acetylcholinergic receptors, LNAChR, and in order to assess activity and toxicity profiles of the drug’s metabolites, synthesis of the main metabolites was undertaken. This synthesis work was done in parallel by organic chemistry and by biotransformation of LNAChR. Filamentous fungus Aspergillus alliaceus (NRRL 315) neatly afforded three of the main metabolites, one of which arose from a very unexpected and very uncommon rearrangement.     

Understanding Providers’ Offering and Patients’ Acceptance of HIV Screening in Emergency Departments: A Multilevel Analysis. ANRS 95008, Paris,France

Objective

We assessed the EDs’ characteristics associated with the offer and acceptance rates of a nontargeted HIV rapid-test screening in 29 Emergency Departments (EDs) in the metropolitan Paris region (11.7 million inhabitants), where half of France’s new HIV cases are diagnosed annually.

Methods

EDs nurses offered testing to all patients 18–64-year-old, able to provide consent, either with or without supplemental staff (hybrid staff model or indigenous staff model). The EDS’ characteristics collected included structural characteristics (location, type, size), daily workload (patients’ number and severity, length of stay in hours), staff’s participation (training, support to the intervention, leadership), type of week day (weekends vs weekdays) and time (in days). Associations between these variables and the staff model, the offer and acceptance rates were studied using multilevel modeling.

Results

Indigenous staff model was more frequent in EDs with a lower daily patient flow and a higher staff support score to the intervention. In indigenous-model EDs, the offer rate was associated with the patient flow (OR = 0.838, 95% CI = 0.773–0.908), was lower during weekends (OR = 0.623, 95% CI = 0.581–0.667) and decreased over time (OR = 0.978, 95% CI = 0.975–0.981). Similar results were found in hybrid-model EDs. Acceptance was poorly associated with EDs characteristics in indigenous-model EDs while in hybrid-model EDs it was lower during weekends (OR = 0.713, 95% CI = 0.623–0.816) and increased after the first positive test (OR = 1.526, 95% CI = 1.142–2.038).The EDs’ characteristics explained respectively 38.5% and 15% of the total variance in the offer rate across indigenous model-EDs and hybrid model-EDs vs 12% and 1% for the acceptance rate.

Conclusion

Our findings suggest the need for taking into account EDs’ characteristics while considering the implementation of an ED-based HIV screening program. Strategies allowing the optimization of human resources’ utilization such as HIV targeted screening in the EDs might be privileged.