A Comparison Between Bonobos and Chimpanzees: A Review and Update

Chimpanzees (Pan troglodytes) and bonobos (P. paniscus) are our closest living relatives, with the human lineage diverging from the Pan lineage only around five to seven Mya, but possibly as early as eight Mya.^1–2 Chimpanzees and bonobos even share genetic similarities with humans that they do not share with each other.² Given their close genetic relationship to humans, both Pan species represent crucial living models for reconstructing our last common ancestor (LCA) and identifying uniquely human features. Comparing the similarities and differences of the two Pan is thus essential for constructing balanced models of human evolution.³     

Population and Single-Cell Analysis of Human Cardiogenesis Reveals Unique LGR5 Ventricular Progenitors in Embryonic Outflow Tract

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Virulence‐associated protein A from Rhodococcus equi is an intercompartmental pH‐neutralising virulence factor

Professional phagocytic cells such as macrophages are a central part of innate immune defence. They ingest microorganisms into membrane‐bound compartments (phagosomes), which acidify and eventually fuse with lysosomes, exposing their contents to a microbicidal environment. Gram‐positive Rhodococcus equi can cause pneumonia in young foals and in immunocompromised humans. The possession of a virulence plasmid allows them to subvert host defence mechanisms and to multiply in macrophages. Here, we show that the plasmid‐encoded and secreted virulence‐associated protein A (VapA) participates in exclusion of the proton‐pumping vacuolar‐ATPase complex from phagosomes and causes membrane permeabilisation, thus contributing to a pH‐neutral phagosome lumen. Using fluorescence and electron microscopy, we show that VapA is also transferred from phagosomes to lysosomes where it permeabilises the limiting membranes for small ions such as protons. This permeabilisation process is different from that of known membrane pore formers as revealed by experiments with artificial lipid bilayers. We demonstrate that, at 24 hr of infection, virulent R. equi is contained in a vacuole, which is enriched in lysosome material, yet possesses a pH of 7.2 whereas phagosomes containing a vapA deletion mutant have a pH of 5.8 and those with virulence plasmid‐less sister strains have a pH of 5.2. Experimentally neutralising the macrophage endocytic system allows avirulent R. equi to multiply. This observation is mirrored in the fact that virulent and avirulent R. equi multiply well in extracts of purified lysosomes at pH 7.2 but not at pH 5.1. Together these data indicate that the major function of VapA is to generate a pH‐neutral and hence growth‐promoting intracellular niche. VapA represents a new type of Gram‐positive virulence factor by trafficking from one subcellular compartment to another, affecting membrane permeability, excluding proton‐pumping ATPase, and consequently disarming host defences.     

Directed cortical information flow during human object recognition: analyzing induced EEG gamma-band responses in brain's source space

The increase of induced gamma-band responses (iGBRs; oscillations >30 Hz) elicited by familiar (meaningful) objects is well established in electroencephalogram (EEG) research. This frequency-specific change at distinct locations is thought to indicate the dynamic formation of local neuronal assemblies during the activation of cortical object representations. As analytically power increase is just a property of a single location, phase-synchrony was introduced to investigate the formation of large-scale networks between spatially distant brain sites. However, classical phase-synchrony reveals symmetric, pair-wise correlations and is not suited to uncover the directionality of interactions. Here, we investigated the neural mechanism of visual object processing by means of directional coupling analysis going beyond recording sites, but rather assessing the directionality of oscillatory interactions between brain areas directly. This study is the first to identify the directionality of oscillatory brain interactions in source space during human object recognition and suggests that familiar, but not unfamiliar, objects engage widespread reciprocal information flow. Directionality of cortical information-flow was calculated based upon an established Granger-Causality coupling-measure (partial-directed coherence; PDC) using autoregressive modeling. To enable comparison with previous coupling studies lacking directional information, phase-locking analysis was applied, using wavelet-based signal decompositions. Both, autoregressive modeling and wavelet analysis, revealed an augmentation of iGBRs during the presentation of familiar objects relative to unfamiliar controls, which was localized to inferior-temporal, superior-parietal and frontal brain areas by means of distributed source reconstruction. The multivariate analysis of PDC evaluated each possible direction of brain interaction and revealed widespread reciprocal information-transfer during familiar object processing. In contrast, unfamiliar objects entailed a sparse number of only unidirectional connections converging to parietal areas. Considering the directionality of brain interactions, the current results might indicate that successful activation of object representations is realized through reciprocal (feed-forward and feed-backward) information-transfer of oscillatory connections between distant, functionally specific brain areas.     

Differences in variation of human immunodeficiency virus type 1 sequences from Henan and Shanghai regions of China

Illegally paid blood donation was a risk factor for HIV acquisition exclusively in Henan and Hubei Provinces of China, and not in Shanghai. Nucleotide sequences in the gag and env genes of HIV-1 were compared between isolates from Henan and Shanghai regions of China to test whether an expected higher degree of a common source of infections from this unique blood donation transmission risk would be evident as decreased variation among Henan isolates in an exploratory cross-sectional analysis. Among 38 isolates studied, 23 of 23 (100%) from Henan and 8 of 15 (54%) from Shanghai were subtype B. In addition, fewer sequence differences were found in gp41 of subtype B isolates from Henan than from Shanghai isolates. Further studies with additional controls are therefore warranted to confirm the role of the degree of a common source of infections in differences in HIV variation across populations. Fundation items: The Vanderbilt-Meharry Center for AIDS Research (P30 AI 54999); R.T.D (R01 AI 29193); Start Fund of Ministry of Education of China (for Hong-zhou LU, 2004BA719A10).     

The renewal and differentiation of Isl1+ cardiovascular progenitors are controlled by a Wnt/beta-catenin pathway

Isl1(+) cardiovascular progenitors and their downstream progeny play a pivotal role in cardiogenesis and lineage diversification of the heart. The mechanisms that control their renewal and differentiation are largely unknown. Herein, we show that the Wnt/beta-catenin pathway is a major component by which cardiac mesenchymal cells modulate the prespecification, renewal, and differentiation of isl1(+) cardiovascular progenitors. This microenvironment can be reconstituted by a Wnt3a-secreting feeder layer with ES cell-derived, embryonic, and postnatal isl1(+) cardiovascular progenitors. In vivo activation of beta-catenin signaling in isl1(+) progenitors of the secondary heart field leads to their massive accumulation, inhibition of differentiation, and outflow tract (OFT) morphogenic defects. In addition, the mitosis rate in OFT myocytes is significantly reduced following beta-catenin deletion in isl1(+) precursors. Agents that manipulate Wnt signals can markedly expand isl1(+) progenitors from human neonatal hearts, a key advance toward the cloning of human isl1(+) heart progenitors.     

Standardisation of rapid in-gel digestion by mass spectrometry

In-gel digestion has been standardised using a poly(propylene) disposable. We designed a four-step rapid and simple in-gel digestion protocol which is carried out in one self-contained reaction tube avoiding keratin contamination. In order to quantify the efficiency of in-gel digestion, we developed a rapid on-column peptide acetylation protocol. Results show that trypsin in-gel uptake is increased and in-gel digestion is 90% complete within 15 min. We further show that spectrum quality, peptide yield and sequence coverage for mass spectrometric analysis are enhanced. We utilise 2-D PAGE separation of photosystem II from barley to demonstrate that the protocol facilitates identification of highly hydrophobic membrane proteins.