Allomaternal care is a rare, though phylogenetically widespread, mammalian infant care strategy. Among primates, the effects of allomaternal care are marked; its presence correlates with faster ...infant growth, younger age at weaning, and shorter interbirth intervals. Recent comparative research has found that such fertility benefits are absent in other mammals and are thus unique to primates. In large part because data describing lemur allomaternal care were lacking, the reproductive advantages of allomaternal care have never been demonstrated in Malagasy strepsirrhines. Using newly available data and rigorous phylogenetic methods, we extend this hypothesis to strepsirrhines and test whether allomaternal care in lemurs confers similar maternal reproductive benefits. Contrary to expectations, the presence of allomaternal care did not significantly impact lemur reproductive output; we did not find relationships between allomaternal care and either fetal or postnatal growth rates or interbirth intervals. Rather, infant parking and nesting, strategies employed primarily by litter-bearing species, were positively associated with faster fetal and postnatal infant growth, while nesting was negatively associated with interbirth interval. Thus, although each form of haplorrhine allomaternal care is also observed in Malagasy primates, the effects that these behaviors have on female reproductive output more closely resemble nonprimate mammals. We suggest that Malagasy strepsirrhines may not equally benefit from allomaternal care compared to haplorrhines because reproductive rates are less flexible and allomaternal care may instead increase infant survival in Madagascar's harsh and unpredictable environment. Our study has significant implications for understanding the evolution of infant care and developmental trajectories in mammals.
Recent studies demonstrate that inflammatory signals regulate hematopoietic stem cells (HSCs). Granulocyte colony-stimulating factor (G-CSF) is often induced with infection and has a key role in the ...stress granulopoiesis response. However, its effects on HSCs are less clear. Herein, we show that treatment with G-CSF induces expansion and increased quiescence of phenotypic HSCs, but causes a marked, cell-autonomous HSC repopulating defect associated with induction of Toll-like receptor (TLR) expression and signaling. The G-CSF-mediated expansion of HSCs is reduced in mice lacking TLR2, TLR4 or the TLR signaling adaptor MyD88. Induction of HSC quiescence is abrogated in mice lacking MyD88 or in mice treated with antibiotics to suppress intestinal flora. Finally, loss of TLR4 or germ-free conditions mitigates the G-CSF-mediated HSC repopulating defect. These data suggest that low-level TLR agonist production by commensal flora contributes to the regulation of HSC function and that G-CSF negatively regulates HSCs, in part, by enhancing TLR signaling.
Summary
The composition of extracellular polymeric substances (EPS) from Shewanella sp. HRCR‐1 biofilms was investigated using infrared spectroscopy and proteomics to provide insight into potential ...ecophysiological functions and redox activity of the EPS. Both bound and loosely associated EPS were extracted from Shewanella sp. HRCR‐1 biofilms prepared using a hollow‐fibre membrane biofilm reactor. Fourier transform infrared spectra revealed the presence of proteins, polysaccharides, nucleic acids, membrane lipids and fatty acids in the EPS fractions. Using a global proteomic approach, a total of 58 extracellular and outer membrane proteins were identified in the EPS. These included homologues of multiple Shewanella oneidensis MR‐1 proteins that potentially contribute to key physiological biofilm processes, such as biofilm‐promoting protein BpfA, surface‐associated serine protease, nucleotidases (CpdB and UshA), an extracellular lipase, and oligopeptidases (PtrB and a M13 family oligopeptidase lipoprotein). In addition, 20 redox proteins were found in extracted EPS. Among the detected redox proteins were the homologues of two S. oneidensis MR‐1 c‐type cytochromes, MtrC and OmcA, which have been implicated in extracellular electron transfer. Given their detection in the EPS of Shewanella sp. HRCR‐1 biofilms, c‐type cytochromes may contribute to the possible redox activity of the biofilm matrix and play important roles in extracellular electron transfer reactions.
Genome-scale prediction of gene regulation and reconstruction of transcriptional regulatory networks in bacteria is one of the critical tasks of modern genomics. The Shewanella genus is comprised of ...metabolically versatile gamma-proteobacteria, whose lifestyles and natural environments are substantially different from Escherichia coli and other model bacterial species. The comparative genomics approaches and computational identification of regulatory sites are useful for the in silico reconstruction of transcriptional regulatory networks in bacteria.
To explore conservation and variations in the Shewanella transcriptional networks we analyzed the repertoire of transcription factors and performed genomics-based reconstruction and comparative analysis of regulons in 16 Shewanella genomes. The inferred regulatory network includes 82 transcription factors and their DNA binding sites, 8 riboswitches and 6 translational attenuators. Forty five regulons were newly inferred from the genome context analysis, whereas others were propagated from previously characterized regulons in the Enterobacteria and Pseudomonas spp.. Multiple variations in regulatory strategies between the Shewanella spp. and E. coli include regulon contraction and expansion (as in the case of PdhR, HexR, FadR), numerous cases of recruiting non-orthologous regulators to control equivalent pathways (e.g. PsrA for fatty acid degradation) and, conversely, orthologous regulators to control distinct pathways (e.g. TyrR, ArgR, Crp).
We tentatively defined the first reference collection of ~100 transcriptional regulons in 16 Shewanella genomes. The resulting regulatory network contains ~600 regulated genes per genome that are mostly involved in metabolism of carbohydrates, amino acids, fatty acids, vitamins, metals, and stress responses. Several reconstructed regulons including NagR for N-acetylglucosamine catabolism were experimentally validated in S. oneidensis MR-1. Analysis of correlations in gene expression patterns helps to interpret the reconstructed regulatory network. The inferred regulatory interactions will provide an additional regulatory constrains for an integrated model of metabolism and regulation in S. oneidensis MR-1.
Understanding biological systems and the roles of their constituents is facilitated by the ability to make quantitative, sensitive, and comprehensive measurements of how their proteome changes, e.g., ...in response to environmental perturbations. To this end, we have developed a high-throughput methodology to characterize an organism's dynamic proteome based on the combination of global enzymatic digestion, high-resolution liquid chromatographic separations, and analysis by Fourier transform ion cyclotron resonance mass spectrometry. The peptides produced serve as accurate mass tags for the proteins and have been used to identify with high confidence >61% of the predicted proteome for the ionizing radiation-resistant bacterium Deinococcus radiodurans. This fraction represents the broadest proteome coverage for any organism to date and includes 715 proteins previously annotated as either hypothetical or conserved hypothetical.
•1,5-Dimethylbicyclo3.2.1octan-8-one-oxime; a safety assessment based on RIFM's criteria.•A safety assessment based on 7 human health endpoints plus environmental.•All endpoints were cleared using ...target data, read-across, and/or TTC.
The three-dimensional(3D) organization of the eukaryotic genome is critical for its proper function. Evidence suggests that extensive chromatin loops form the building blocks of the genomic ...architecture, separating genes and gene clusters into distinct functional domains. These loops are anchored in part by a special type of DNA elements called chromatin boundary elements(CBEs). CBEs were originally found to insulate neighboring genes by blocking influences of transcriptional enhancers or the spread of silent chromatin. However, recent results show that chromatin loops can also play a positive role in gene regulation by looping out intervening DNA and 'delivering' remote enhancers to gene promoters. In addition, studies from human and model organisms indicate that the configuration of chromatin loops, many of which are tethered by CBEs, is dynamically regulated during cell differentiation. In particular, a recent work by Li et al has shown that the SF1 boundary, located in the Drosophila Hox cluster, regulates local genes by tethering different subsets of chromatin loops: One subset enclose a neighboring gene ftz, limiting its access by the surrounding Scr enhancers and restrict the spread of repressive histones during early embryogenesis; and the other loops subdivide the Scr regulatory region into independent domains of enhancer accessibility. The enhancer-blocking activity of these CBE elements varies greatly in strength and tissue distribution. Further, tandem pairing of SF1 and SF2 facilitate the bypass of distal enhancers in transgenic flies, providing a mechanism for endogenous enhancers to circumvent genomic interruptions resulting from chromosomal rearrangement. This study demonstrates how a network of chromatin boundaries, centrally organized by SF1, can remodel the 3D genome to facilitate gene regulation during development.
•Menthyl acetate (isomer unspecified); a safety assessment based on RIFM's criteria.•A safety assessment based on 7 human health endpoints plus environmental.•All endpoints were cleared using target ...data, read-across, and/or TTC.
•Orange essence oil; a safety assessment based on RIFM's criteria.•A safety assessment based on 7 human health endpoints plus environmental.•All endpoints were cleared using target data, read-across, ...and/or TTC.
•Acetyl cedrene; a safety assessment based on RIFM's criteria.•A safety assessment based on 7 human health endpoints plus environmental.•All endpoints were cleared using target data, read-across, ...and/or TTC.
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