Loss of phylogenetic information in chorion gene families of Bombyx mori gene conversion

The silkmoth chorion has provided a stimulating model for the study of evolution and developmental regulation of gene families. Previous attempts at inferring relationships among chorion sequences have been based on pairwise comparisons of overall similarity, a potentially problematic approach. To remedy this, we identified the alignable regions of low sequence variability and then analyzed this restricted database by parsimony and neighbor-joining methods. At the deepest level, the chorion sequence tree is split into two branches, called "alpha" and "beta." Within each branch, early- and late-expressing genes each constitute monophyletic groups, while the situation with middle-expressing genes remains uncertain. The HcB gene family appears to be the most basal beta-branch group, but this conclusion is qualified because the effect of gene conversion on branching order is unknown. Previous studies by Eickbush and colleagues have strongly suggested that ErA, HcA, and HcB families undergo gene conversion within a gene family, whereas the ErB family does not. The occurrence of conversion correlates with a particular tree structure; namely, branch lengths are much greater at the base of the family than at higher internodes and terminal branches. These observations raise the possibility that chorion gene families are defined by gene conversion events (reticulate evolution) rather than by descent with modification (synapomorphy).      

First record of a spiral form of Aulacoseira,A. ambigua f. japonica (F.Meister) Tuji & D.M.Williams,in South African fresh waters

Water quality and algal populations in the Vaal River Barrage Reservoir have been monitored extensively for many decades, because of its importance as a water source for the most densely populated area in South Africa. Although Aulacoseira granulata (Ehrenberg) Simonsen is frequently found and at it times dominates algal assemblages in the Barrage, Aulacoseira ambigua (F.Meister) Tuji & D.M.Williams has never before been recorded at this locality. During a countrywide proficiency-testing scheme for algae counting, coordinated by Rand Water, spiral-shaped diatom colonies with distinctly curved cells were detected during May 2015. Upon investigation, it was found that the spiral colonies were Aulacoseira ambigua f. japonica, its presence in the fresh waters of South Africa being recorded for the first time. Since their first appearance during May 2015, colonies of Aulacoseira ambigua f. japonica have been constantly present in the surface waters of the Barrage. Their presence at this site can be linked to increasing eutrophication in the Vaal River, because the spiral form is known to prefer eutrophic conditions. Centric diatoms rarely form spiral colonies and there is some confusion in the literature as to the identity of this particular form, therefore in this paper we discuss this taxon, its nomenclature and ecological significance.     

Calcium-induced acetylcholine release and intramembrane particle occurrence in proteoliposomes equipped with mediatophore.

Proteoliposomes obtained from the mediatophore, a purified Torpedo electric organ nerve terminals protein, and endogenous lipids were used for a study of calcium-induced release of acetylcholine and freeze-fracture electron microscopy. Large intramembrane particles were induced by the influx of calcium into proteoliposomes, as previously observed for synaptosomes or stimulated electric organ nerve terminals. The involvement of mediatophore in a calcium dependent acetylcholine translocation seems therefore to be related to the occurrence of a category of intramembrane particles in the course of the release process.     

De novo ceramide synthesis is responsible for the anti-tumor properties of camptothecin and doxorubicin in follicular thyroid carcinoma

Doxorubicin and camptothecin are two cytotoxic chemotherapeutic agents triggering apoptosis in various cancer cells, including thyroid carcinoma cells. Recent studies revealed a critical role of ceramide in chemotherapy and suggested that anti-cancer drugs may kill tumor cells through sphingomyelinase activation. However, in comparison to sphingomyelin hydrolysis, the relative involvement of de novo ceramide synthesis remained poorly explored and highly controversial. Here, we evidenced that both doxorubicin and camptothecin triggered ceramide accumulation in thyroid carcinoma cells. We demonstrated that ceramide increase occurred via the de novo pathway without neither acidic nor neutral sphingomyelinase contribution. Interestingly, de novo ceramide generation was responsible for the drug-induced malignant cell apoptosis through a caspase-3-dependent pathway and a decrease of thrombospondin amount. Furthermore, blocking ceramide metabolism by inhibiting glucosylceramide synthase strengthened the camptothecin and doxorubicin-dependent effects. Altogether, we evidenced that de novo ceramide synthesis mediates the anti-tumor properties of doxorubicin and camptothecin in thyroid carcinoma and suggested that glucosylation of ceramide may contribute to the drug-resistance phenotype in thyroid malignancies.     

THUMP from archaeal tRNA:m22G10 methyltransferase, a genuine autonomously folding domain

The tRNA:m²₂G10 methyltransferase of Pyrococus abyssi (PAB1283, a member of COG1041) catalyzes the N²,N²-dimethylation of guanosine at position 10 in tRNA. Boundaries of its THUMP (THioUridine synthases, RNA Methyltransferases and Pseudo-uridine synthases)—containing N-terminal domain [1–152] and C-terminal catalytic domain [157–329] were assessed by trypsin limited proteolysis. An inter-domain flexible region of at least six residues was revealed. The N-terminal domain was then produced as a standalone protein (THUMPα) and further characterized. This autonomously folded unit exhibits very low affinity for tRNA. Using protein fold-recognition (FR) methods, we identified the similarity between THUMPα and a putative RNA-recognition module observed in the crystal structure of another THUMP-containing protein (ThiI thiolase of Bacillus anthracis). A comparative model of THUMPα structure was generated, which fulfills experimentally defined restraints, i.e. chemical modification of surface exposed residues assessed by mass spectrometry, and identification of an intramolecular disulfide bridge. A model of the whole PAB1283 enzyme docked onto its tRNA^Asp substrate suggests that the THUMP module specifically takes support on the co-axially stacked helices of T-arm and acceptor stem of tRNA and, together with the catalytic domain, screw-clamp structured tRNA. We propose that this mode of interactions may be common to other THUMP-containing enzymes that specifically modify nucleotides in the 3D-core of tRNA.     

Human thyroid carcinoma cell invasion is controlled by the low density lipoprotein receptor-related protein-mediated clearance of urokinase plasminogen activator

The low density lipoprotein receptor-related protein (LRP), a large scavenger receptor reported to mediate the uptake and degradation of various ligands, emerges as a promising receptor for targeting the invasive behaviour of human cancer cells. However, the accurate function of LRP during tumor invasion seems to be highly dependent on cellular context and remains controversial. The expression patterns of both this receptor and the main proteolytic systems involved in cell invasion were examined in two follicular thyroid carcinoma cell lines exhibiting different invasive phenotypes. We established that a low expression of LRP at the cell surface was associated to elevated extracellular MMP2 and urokinase plasminogen activator (uPA) activities as well as to high invasiveness properties. Surprisingly, neither exogenously added receptor-associated protein, an antagonist of LRP, nor LRP blocking antibodies significantly modified the amount of extracellular MMP2. Furthermore, the invasive phenotype of thyroid carcinoma cells was not related to their matrix metalloproteinases amount since different specific inhibitors of these proteases failed to affect the invasive properties of both cell lines. Additionally, blocking LRP-mediated clearance led to a further increase of the uPA amount and activities and to increased invasiveness in both cell lines. Finally thyroid carcinoma cells aggressiveness was widely increased by exogenous uPA; and anti-uPA antibodies treatments abolished both basal and receptor-associated protein-induced thyroid cell invasion. Overall our results identified the LRP-mediated clearance of uPA as one of the mechanisms involved during the control of human thyroid carcinoma cell invasion.     

7th SOSORT consensus paper: conservative treatment of idiopathic & Scheuermann's kyphosis

Abstract

Thoracic hyperkyphosis is a frequent problem and can impact greatly on patient's quality of life during adolescence. This condition can be idiopathic or secondary to Scheuermann disease, a disease disturbing vertebral growth. To date, there is no sound scientific data available on the management of this condition. Some studies discuss the effects of bracing, however no guidelines, protocols or indication's of treatment for this condition were found. The aim of this paper was to develop and verify the consensus on managing thoracic hyperkyphosis patients treated with braces and/or physiotherapy.

Methods

The Delphi process was utilised in four steps gradually modified according to the results of a set of recommendations: we involved the SOSORT Board twice, then all SOSORT members twice, with a Pre-Meeting Questionnaire (PMQ), and during a Consensus Session at the SOSORT Lyon Meeting with a Meeting Questionnaire (MQ).

Results

There was an unanimous agreement on the general efficacy of bracing and physiotherapy for this condition. Most experts suggested the use of 4-5 point bracing systems, however there was some controversy with regards to physiotherapeutic aims and modalities.

Conclusion

The SOSORT panel of experts suggest the use of rigid braces and physiotherapy to correct thoracic hyperkyphosis during adolescence. The evaluation of specific braces and physiotherapy techniques has been recommended.     

Revisiting iodination sites in thyroglobulin with an organ-oriented shotgun strategy

Thyroglobulin (Tg) is secreted by thyroid epithelial cells. It is essential for thyroid hormonogenesis and iodine storage. Although studied for many years, only indirect and partial surveys of its post-translational modifications were reported. Here, we present a direct proteomic approach, used to study the degree of iodination of mouse Tg without any preliminary purification. A comprehensive coverage of Tg was obtained using a combination of different proteases, MS/MS fragmentation procedures with inclusion lists and a hybrid mass high-resolution LTQ-Orbitrap XL mass spectrometer. Although only 16 iodinated sites are currently known for human Tg, we uncovered 37 iodinated tyrosine residues, most of them being mono- or diiodinated. We report the specific isotopic pattern of thyroxine modification, not recognized as a normal peptide pattern. Four hormonogenic sites were detected. Two donor sites were identified through the detection of a pyruvic acid residue in place of the initial tyrosine. Evidence for polypeptide cleavages sites due to the action of cathepsins and dipeptidyl proteases in the thyroid were also detected. This work shows that semi-quantitation of Tg iodination states is feasible for human biopsies and should be of significant medical interest for further characterization of human thyroid pathologies.