Ancient connection between NKL genes and the mesoderm? Insights from <Emphasis Type="Italic">Tlx</Emphasis> expression in a ctenophore

In recent years, evo-devo studies on non-bilaterian metazoans have improved our understanding of the early evolution of animal body plans. In particular, works on cnidarians suggested that contrary to classical views, the mesoderm originated far before the emergence of the Bilateria. In this context, a synthesis of genomic and functional data concerning the Antennapedia (Antp) superclass of homeobox genes suggested that early in animal evolution, each of the three germ layers was under the control of one cluster of Antp genes. In particular, the patterning and differentiation of the mesoderm was under the control of the NKL cluster. The ctenophores stand as a key taxon with respect to such issues because unlike other non-bilaterian phyla, their intermediate germ layer satisfies the strict embryological definition of a mesoderm. For that reason, we investigated the only known member of the NKL group in Ctenophora, a gene previously isolated from Pleurobrachia and attributed to the Tlx family. In our analysis of the NKL group, this ctenophore gene branches as the sister-group of bilaterian Tlx genes, but without statistical support. The expression pattern of this gene was revealed by in situ hybridisation in the adult ctenophore. The expression territories of PpiTlx are predominantly ectodermal, in two distinct types of ciliated epidermal cells and in one category of gland cells. We also identified a probable endodermal site of expression. Because we failed to detect any mesodermal expression, the results do not provide support to the hypothesis of an ancient functional association between the NKL group and the mesoderm.     

Localization of cocaine analog [125I]RTI 82 irreversible binding to transmembrane domain 6 of the dopamine transporter

The site of cocaine binding on the dopamine transporter (DAT) was investigated using the photoactivatable irreversible cocaine analog [125I]3beta-(p-chlorophenyl)tropane-2beta-carboxylic acid, 4'-azido-3'-iodophenylethyl ester ([125I]RTI 82). The incorporation site of this compound was mapped to transmembrane domains (TMs) 4-6 using epitope-specific immunoprecipitation of trypsin fragments and further localized using cyanogen bromide (CNBr), which hydrolyzes proteins on the C-terminal side of methionine residues. CNBr hydrolysis of [125I]RTI 82-labeled rat striatal and expressed human DATs produced fragments of approximately 5-10 kDa consistent with labeling between Met(271/272) or Met(290) in TM5 to Met(370/371) in TM7. To further define the incorporation site, substitution mutations were made that removed endogenous methionines and inserted exogenous methionines in combinations that would generate labeled CNBr fragments of distinct masses depending on the labeling site. The results obtained were consistent with the presence of TM6 but not TMs 4, 5, or 7 in the labeled fragments, with additional support for these conclusions obtained by epitope-specific immunoprecipitation and secondary digestion of CNBr fragments with endoproteinase Lys-C. The final localization of [125I]RTI 82 incorporation to rat DAT Met(290)-Lys(336) and human DAT I291M to R344M provides positive evidence for the proximity of cocaine binding to TM6. Residues in and near DAT TM6 regulate transport and transport-dependent conformational states, and TM6 forms part of the substrate permeation pathway in the homologous Aquifex aeolicus leucine transporter. Cocaine binding near TM6 may thus overlap the dopamine translocation pathway and function to inhibit TM6 structural rearrangements necessary for transport.     

Lymphocytes and the Dap12 adaptor are key regulators of osteoclast activation associated with gonadal failure

Bone resorption by osteoclasts is necessary to maintain bone homeostasis. Osteoclast differentiation from hematopoietic progenitors and their activation depend on M-CSF and RANKL, but also requires co-stimulatory signals acting through receptors associated with DAP12 and FcRgamma adaptors. Dap12 mutant mice (KDelta75) are osteopetrotic due to inactive osteoclasts but, surprisingly, these mice are more sensitive than WT mice to bone loss following an ovariectomy. Because estrogen withdrawal is known to disturb bone mass, at least in part, through lymphocyte interaction, we looked at the role of mature lymphocytes on osteoclastogenesis and bone mass in the absence of functional DAP12. Lymphocytes were found to stimulate an early osteoclast differentiation response from Dap12-deficient progenitors in vitro. In vivo, Rag1-/- mice lacking mature lymphocytes did not exhibit any bone phenotype, but lost their bone mass after ovariectomy like KDelta75 mice. KDelta75;Rag1-/- double mutant female mice exhibited a more severe osteopetrosis than Dap12-deficient animals but lost their bone mass after ovariectomy, like single mutants. These results suggest that both DAP12 and mature lymphocytes act synergistically to maintain bone mass under physiological conditions, while playing similar but not synergistic co-stimulatory roles in protecting bone loss after gonadal failure. Thus, our data support a role for lymphocytes during osteoclast differentiation and suggest that they may function as accessory cells when regular osteoclast function is compromised.     

Network Reconstruction and Significant Pathway Extraction Using Phosphoproteomic Data from Cancer Cells

Protein phosphorylation acts as an efficient switch controlling deregulated key signaling pathway in cancer. Computational biology aims to address the complexity of reconstructed networks but overrepresents well‐known proteins and lacks information on less‐studied proteins. A bioinformatic tool to reconstruct and select relatively small networks that connect signaling proteins to their targets in specific contexts is developed. It enables to propose and validate new signaling axes of the Syk kinase. To validate the potency of the tool, it is applied to two phosphoproteomic studies on oncogenic mutants of the well‐known phosphatidyl‐inositol 3‐kinase (PIK3CA) and the unfamiliar Src‐related tyrosine kinase lacking C‐terminal regulatory tyrosine and N‐terminal myristoylation sites (SRMS) kinase. By combining network reconstruction and signal propagation, comprehensive signaling networks from large‐scale experimental data are built and multiple molecular paths from these kinases to their targets are extracted. Specific paths from two distinct PIK3CA mutants are retrieved, and their differential impact on the HER3 receptor kinase is explained. In addition, to address the missing connectivities of the SRMS kinase to its targets in interaction pathway databases, phospho‐tyrosine and phospho‐serine/threonine proteomic data are integrated. The resulting SRMS‐signaling network comprises casein kinase 2, thereby validating its currently suggested role downstream of SRMS. The computational pipeline is publicly available, and contains a user‐friendly graphical interface ( http://doi.org/10.5281/zenodo.3333687 ).     

Advanced Alkali Treatments for High‐Efficiency Cu(In,Ga)Se2 Solar Cells on Flexible Substrates

Flexible, lightweight Cu(In,Ga)Se₂ (CIGS) solar cells grown on polymer substrates are a promising technology with fast growing market prospects. However, power conversion efficiencies of solar cells grown at low temperatures (≈450 °C) remain below the efficiencies of cells grown at high temperature on glass substrates. This contribution discusses the impact on cell efficiency of process improvements of low‐temperature CIGS deposition on flexible polyimide and glass substrates. Different strategies for incorporation of alkali elements into CIGS are evaluated based on a large number of depositions. Postdeposition treatment with heavy alkali (here RbF) enables a thickness reduction of the CdS buffer layer and increases the open‐circuit voltage. Na supply during 3rd stage CIGS deposition positively impacts the cell performance. Coevaporation of heavy alkali (e.g., RbF) during capping layer deposition mitigates the adverse shunting associated with high Cu contents, yielding highest efficiencies with near‐stoichiometric absorber compositions. Furthermore, optimization of the deposition sequence results in absorbers with a 1 µm wide notch region with nearly constant bandgap minimum. The improved processes result in a record cell efficiency of 20.8% for CIGS on flexible substrate.     

Analysis of the S. pombe Meiotic Proteome Reveals a Switch from Anabolic to Catabolic Processes and Extensive Post-transcriptional Regulation

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Effects of environmental temperature and exercise on the biochemical characteristics of hamster intestine

The effects of increasing environmental temperature and of exercise on some biochemical characteristics of the intestinal mucosa were analyzed in hamsters to determine whether damage occurs to the intestine during exercise, because long-distance runners complain of cramp, diarrhea, or retrostaltic symptoms, especially when exercise is performed at high temperatures. Two sets of experiments were carried out on groups of five animals. First, one group stayed at rest at 20 degrees C while another group performed exercise for 30 min at the same temperature. Second, one group of animals remained at rest at 20 degrees C for 16 h, a second group was placed at 32 degrees C for the same period, and a third group was subjected to the latter treatment but in addition performed two 20-min exercises. The animals were killed immediately after the experiment. After the small bowel was removed, biopsies were taken for histological examination, and the remaining small bowel tissue was homogenized for biochemical analysis. During exercise performed at 20 degrees C or during exposure to 32 degrees C, the DNA weight (expressed as a function of the protein weight) increased; the specific activity of sucrase, leucine aminopeptidase, diamine oxidase, and maltase decreased; spermine and putrescine content generally decreased; and the weight of mucosal proteins per length of intestine did not vary significantly. When exercise was performed at 32 degrees C, we noted few modifications in the values of the intestinal parameters tested, i.e., changes in only the weight of mucosa expressed as a function of bowel length and, perhaps, the spermine or putrescine content.     

The last African white giraffes live in farmers’ fields

The giraffe population (Giraffa camelopardalis) in Niger is the last representative of the peralta sub-species which lived throughout West Africa at the beginning of the twentieth century. Protected since the 1970s, giraffes cohabit with humans in cultivated landscapes. This may not have appeared to pose many problems in the past, but the relationship between farmers and giraffes has deteriorated with the expansion of cultivated land and that of the giraffe population, with reported cases of giraffes damaging crops. A survey was conducted in all the affected villages in the Kouré area to establish the nature, severity and distribution of the damage and to evaluate the local populations’ perception of the problem. Cowpeas are fed upon in the field at harvest time and in the granaries, as well as ripe mangoes, during the most critical period for giraffes’ nutrition. The vast majority of farmers interviewed consider giraffes to be rather a problem in spite of tourism revenues they can obtain from them. This opinion has individually little correlation with damage rate on crops or easy access to tourism revenues. The damage risk factors are first and foremost considered as uncontrollable by the farmers, even if technical protection measures could easily be put in place locally. The inter-relationships between the socio-economic context and the way the problem is perceived are discussed.     

Melanin is an essential component for the integrity of the cell wall of Aspergillus fumigatus conidia

Background  

Aspergillus fumigatus is the most common agent of invasive aspergillosis, a feared complication in severely immunocompromised patients. Despite the recent commercialisation of new antifungal drugs, the prognosis for this infection remains uncertain. Thus, there is a real need to discover new targets for therapy. Particular attention has been paid to the biochemical composition and organisation of the fungal cell wall, because it mediates the host-fungus interplay. Conidia, which are responsible for infections, have melanin as one of the cell wall components. Melanin has been established as an important virulence factor, protecting the fungus against the host's immune defences. We suggested that it might also have an indirect role in virulence, because it is required for correct assembly of the cell wall layers of the conidia.