Uniquely derived upper molar morphology of Eocene Amphipithecidae (Primates: Anthropoidea): Homology and phylogeny

The extinct Southeast Asian primate family Amphipithecidae is regularly cited in discussions of anthropoid origins, but its phylogenetic position remains controversial. In part, the lack of consensus regarding amphipithecid relationships can be attributed to uncertainty regarding the homology of upper molar structures in this group. Here, we describe a virtually pristine upper molar of Pondaungia cotteri from the late middle Eocene Pondaung Formation of Myanmar, which is the first example of a relatively unworn and well-preserved amphipithecid upper molar ever recovered. The distolingual upper molar cusp in this new specimen of Pondaungia appears to be a lingually displaced and enlarged metaconule, rather than a hypocone or pseudohypocone as previous workers have thought. Reassessment of the upper molar morphology of other amphipithecids and putative amphipithecids reveals a very similar pattern in Siamopithecus, Myanmarpithecus and Ganlea, all of which are interpreted as having upper molars showing many of the same derived features apparent in Pondaungia. In contrast, the upper molar morphology of Bugtipithecus diverges radically from that of undoubted amphipithecids, and the latter taxon is excluded from Amphipithecidae on this basis. Phylogenetic analyses of several character–taxon matrices culled from the recent literature and updated to reflect the new information on amphipithecid upper molar morphology yield similar results. Consensus tree topologies derived from these analyses support amphipithecid monophyly and stable relationships within Amphipithecidae. Amphipithecids appear to be stem members of the anthropoid clade.     

The Influence of Extracorporeal Circulation on the Susceptibility of Erythrocytes to Oxidative Stress

Extracorporeal circulation (ECC), a necessary and integral part of cardiac surgery, can itself induce deleterious effects in patients. The pathogenesis of diffuse damage of several tissues is multifactorial. It is believed that circulation of blood extracorporeally through plastic tubes causes a whole body inflammatory response and a severe shear stress to blood cells. The aim of this study was to evaluate the level of oxidative stress and its deleterious effect on red blood cell (RBC) before (pre-ECC), immediately after (per-ECC) and 24?h after an ECC (24?h post-ECC). Several indicators of extracellular oxidative status were evaluated. The ascorbyl free radical (AFR) was directly measured in plasma using electron spin resonance (ESR) spectroscopy and expressed with respect to vitamin C levels in order to obtain a direct index of oxidative stress. Allophycocyanin assay was also used to investigate the plasma antioxidant status (PAS). Indirect parameters of antioxidant capacities of plasma such as vitamin E, thiol and uric acid levels were also quantified. RBC alterations were evaluated through potassium efflux and carbonyl levels after action of AAPH, a compound generating carbon centered free radicals. No changes in plasma uric acid and thiols levels were observed after ECC. However, vitamin E levels and PAS were decreased in per-ECC and 24?h post-ECC samples. Vitamin C levels were significantly lower in 24?h post-ECC and the AFR/ vitamin C ratio was increased. Differences in results had been noted when measurements took account of hemodilution. Increases of uric acid and thiols levels were observed after ECC. Vitamin E levels were not modified. However after hemodilution correction a significant decrease of vitamin C level was noted in 24?h post-ECC samples as compared to per-ECC sample. Whatever the way of measurement, vitamin C levels decreased suggesting the occurrence of ECC induced-oxidative stress. Concerning RBC, in the absence of AAPH, extracellular potassium remained unchanged between pre-, per- and 24?h post-ECC. AAPH induced a significant increase in extracellular potassium and carbonyls levels of RBC membranes, which was not modified by ECC. These results suggest the absence of alterations of RBC membrane during ECC despite the occurrence of disturbances in PAS. Such protection is of particular importance in a cell engaged in the transport of oxygen and suggests that RBC are equipped with mechanisms affording a protection against free radicals.     

High genetic diversity of in situ and ex situ populations of Madagascan coffee species: further implications for the management of coffee genetic resources

The genetic diversity of endemic Madagascan Coffea species has not received any considerable attention, despite the high extinction threat facing most of the species on the island. In order to address this shortfall, we assessed and compared the genetic diversity and allelic richness of ex situ and in situ populations for four selected species, and 18 ex situ populations maintained at the Kianjavato Coffee Research Station. We also investigated the possibility of in situ and ex situ hybridization events for Madagascan coffee, both within and between species. For these purposes, we used 18 nuclear microsatellite markers, on a total of 37 Coffea populations (4 in situ and 33 ex situ) representing a total of 398 genotypes (96 in situ and 302 ex situ) for 23 species. Our study showed (1) strong differentiation between Madagascan Coffea species; (2) good differentiation between all the populations studied, including those from the same locality (even when the area of the locality was restricted); (3) good evidence for both in situ and ex situ hybridization, although in situ hybridization appeared to be limited; (4) much higher genetic diversity within in situ collections compared to ex situ collections; and (5) that, despite limitations, the Kianjavato Coffee Research Station collection is an extremely valuable resource of Madagascan coffee germplasm. Recommendations for in situ and ex situ germplasm conservation are discussed.     

TGF-beta inhibits human cutaneous melanoma cell migration and invasion through regulation of the plasminogen activator system

Over the past decades, the incidence of cutaneous melanoma in developed countries has increased faster than any other cancer. Although most patients have localized disease at the time of diagnosis and are cured by surgical excision of the primary tumor, melanoma can be highly malignant and the survival dramatically decreases for advanced stage melanomas. It is thus necessary to understand the progression of this disease. Cell migration and invasion promote tumor metastasis, the major cause of melanoma cancer morbidity and death. In this study, we investigated the role of the TGFβ/Smad signaling pathway in melanoma tumor progression and found TGFβ to potently inhibit both cell migration and invasion in human melanoma cell lines, established from different patients. Furthermore, we elucidated the molecular mechanisms by which TGFβ exerts its effects and found the plasminogen activation system (PAS) to play a central role in the regulation of these effects. We found TGFβ to strongly up-regulate the Plasminogen Activator Inhibitor-1 (PAI-1) in melanoma cells, leading to reduced plasmin generation and activity and, in turn to inhibition of cell migration and invasion. Together, our results define TGFβ as a potent suppressor of tumor progression in cutaneous melanoma, inhibiting both cell migration and invasion.     

Disturbance Frequency Determines Morphology and Community Development in Multi-Species Biofilm at the Landscape Scale

Many natural and engineered biofilm systems periodically face disturbances. Here we present how the recovery time of a biofilm between disturbances (expressed as disturbance frequency) shapes the development of morphology and community structure in a multi-species biofilm at the landscape scale. It was hypothesized that a high disturbance frequency favors the development of a stable adapted biofilm system while a low disturbance frequency promotes a dynamic biofilm response. Biofilms were grown in laboratory-scale reactors over a period of 55-70 days and exposed to the biocide monochloramine at two frequencies: daily or weekly pulse injections. One untreated reactor served as control. Biofilm morphology and community structure were followed on comparably large biofilm areas at the landscape scale using automated image analysis (spatial gray level dependence matrices) and community fingerprinting (single-strand conformation polymorphisms). We demonstrated that a weekly disturbed biofilm developed a resilient morphology and community structure. Immediately after the disturbance, the biofilm simplified but recovered its initial complex morphology and community structure between two biocide pulses. In the daily treated reactor, one organism largely dominated a morphologically simple and stable biofilm. Disturbances primarily affected the abundance distribution of already present bacterial taxa but did not promote growth of previously undetected organisms. Our work indicates that disturbances can be used as lever to engineer biofilms by maintaining a biofilm between two developmental states.     

Antimicrobial Resistance in Invasive Non-typhoid Salmonella from the Democratic Republic of the Congo: Emergence of Decreased Fluoroquinolone Susceptibility and Extended-spectrum Beta Lactamases

Background

Co-resistance against the first-line antibiotics ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole or multidrug resistance (MDR) is common in non typhoid Salmonella (NTS). Use of alternative antibiotics, such as fluoroquinolones or third generation cephalosporins is threatened by increasing resistance, but remains poorly documented in Central-Africa.

Methodology/Principal findings

As part of a microbiological surveillance study in DR Congo, blood cultures were collected between 2007 and 2011. Isolated NTS were assessed for serotype and antimicrobial resistance including decreased ciprofloxacin susceptibility and extended-spectrum beta-lactamase (ESBL) production. In total, 233 NTS isolates (representing 23.6% of clinically significant organisms) were collected, mainly consisting of Salmonella Typhimurium (79%) and Salmonella Enteritidis (18%). The majority of NTS were isolated in the rainy season, and recovered from children ≤2 years old. MDR, decreased ciprofloxacin susceptibility, azithromycin and cefotaxime resistance were 80.7%, 4.3%, 3.0% and 2.1% respectively. ESBL production was noted in three (1.3%) isolates. Decreased ciprofloxacin susceptibility was associated with mutations in codon 87 of the gyrA gene, while ESBLs all belonged to the SHV-2a type.

Conclusions/Significance

Presence of almost full MDR among NTS isolates from blood cultures in Central Africa was confirmed. Resistance to fluoroquinolones, azithromycin and third generation cephalosporins is still low, but emerging. Increased microbiological surveillance in DR Congo is crucial for adapted antibiotic therapy and the development of treatment guidelines.     

Molecular Evidence for the Presence of Rickettsia Felis in the Feces of Wild-living African Apes

Background

Rickettsia felis is a common emerging pathogen detected in mosquitoes in sub-Saharan Africa. We hypothesized that, as with malaria, great apes may be exposed to the infectious bite of infected mosquitoes and release R. felis DNA in their feces.

Methods

We conducted a study of 17 forest sites in Central Africa, testing 1,028 fecal samples from 313 chimpanzees, 430 gorillas and 285 bonobos. The presence of rickettsial DNA was investigated by specific quantitative real-time PCR. Positive results were confirmed by a second PCR using primers and a probe targeting a specific gene for R. felis. All positive samples were sequenced.

Results

Overall, 113 samples (11%) were positive for the Rickettsia-specific gltA gene, including 25 (22%) that were positive for R. felis. The citrate synthase (gltA) sequence and outer membrane protein A (ompA) sequence analysis indicated 99% identity at the nucleotide level to R. felis. The 88 other samples (78%) were negative using R. felis-specific qPCR and were compatible with R. felis-like organisms.

Conclusion

For the first time, we detected R. felis in wild-living ape feces. This non invasive detection of human pathogens in endangered species opens up new possibilities in the molecular epidemiology and evolutionary analysis of infectious diseases, beside HIV and malaria.     

Differential Distribution of Genes Encoding the Virulence Factor Trans-Sialidase along Trypanosoma cruzi Discrete Typing Units

Trypanosoma cruzi the agent of Chagas disease is a monophyletic but heterogeneous group conformed by several Discrete Typing Units (DTUs) named TcI to TcVI characterized by genetic markers. The trans-sialidase (TS) is a virulence factor involved in cell invasion and pathogenesis that is differentially expressed in aggressive and less virulent parasite stocks. Genes encoding TS-related proteins are included in a large family divided in several groups but only one of them contains TS genes. Two closely related genes differing in a T/C transition encode the enzymatically active TS (aTS) and a lectin-like TS (iTS). We quantified the aTS/iTS genes from TcII and TcVI aggressive and TcI low virulent strains and found variable aTS number (1–32) per haploid genome. In spite of being low TS enzyme-expressers, TcI strains carry 28–32 aTS gene copies. The intriguing absence of iTS genes in TcI strains together with the presence of aTS/iTS in TcII and TcVI strains (virulent) were observed. Moreover, after sequencing aTS/iTS from 38 isolates collected along the Americas encompassing all DTUs, the persistent absence of the iTS gene in TcI, TcIII and TcIV was found. In addition, the sequence clustering together with T/C transition analysis correlated to DTUs of T. cruzi. The consistence of TS results with both evolutionary genome models proposed for T. cruzi, namely the “Two Hybridization” and the “Three Ancestor” was discussed and reviewed to fit present findings. Parasite stocks to attempt genetic KO or to assay the involvement of iTS in parasite biology and virulence are finally available.     

Activin receptor-like kinase 1 inhibits human microvascular endothelial cell migration: potential roles for JNK and ERK

Activin receptor-like kinase 1 (ALK1) is an endothelial-specific type I receptor of the TGFbeta receptor family that is implicated in angiogenesis and in the pathogenesis of the vascular disease, hereditary hemorrhagic telangiectasia (HHT). In the absence of a specific ligand, ALK1 cellular functions have been mainly studied through the use of a constitutively active form of this receptor (ALK1ca) and are still debated. We previously reported that ALK1ca inhibits proliferation and migration of human endothelial cells suggesting that ALK1 plays an important role in the maturation phase of angiogenesis (Lamouille et al., 2002, Blood 100: 4495-4501). In the present work, we further analyzed the role of ALK1 in the migration of human dermal microvascular endothelial cell (HMVEC-d) and observed that silencing endogenous ALK1 expression with siRNAs accelerates endothelial cell migration in the wound assay. Further, we demonstrate that ALK1-induced inhibition of migration is Smad-independent. Using a panel of kinase inhibitors, we found that HMVEC-d wound closure was completely inhibited by a JNK inhibitor and to a lower degree by an ERK kinase inhibitor. Further, HMVEC-d wounding induced activation of both JNK and ERK, and these were inhibited by ALK1ca expression. Taken together, these results support a significant role for ALK1 as a negative regulator of endothelial cell migration and suggest the implication of JNK and ERK as mediators of this effect.