First Evidence of Reproductive Adaptation to “Island Effect” of a Dwarf Cretaceous Romanian Titanosaur, with Embryonic Integument In Ovo

<div><h3>Background</h3><p>The Cretaceous vertebrate assemblages of Romania are famous for geographically endemic dwarfed dinosaur taxa. We report the first complete egg clutches of a dwarf lithostrotian titanosaur, from Toteşti, Romania, and its reproductive adaptation to the “island effect”.</p> <h3>Methodology/Findings</h3><p>The egg clutches were discovered in sequential sedimentary layers of the Maastrichtian Sânpetru Formation, Toteşti. The occurrence of 11 homogenous clutches in successive strata suggests philopatry by the same dinosaur species, which laid clutches averaging four ∼12 cm diameters eggs. The eggs and eggshells display numerous characters shared with the positively identified material from egg-bearing level 4 of the Auca Mahuevo (Patagonia, Argentina) nemegtosaurid lithostrotian nesting site. Microscopic embryonic integument with bacterial evidences was recovered in one egg. The millimeter-size embryonic integument displays micron size dermal papillae implying an early embryological stage at the time of death, likely corresponding to early organogenesis before the skeleton formation.</p> <h3>Conclusions/Significance</h3><p>The shared oological characters between the Haţeg specimens and their mainland relatives suggest a highly conservative reproductive template, while the nest decrease in egg numbers per clutch may reflect an adaptive trait to a smaller body size due to the “island effect”. The combined presence of the lithostrotian egg and its embryo in the Early Cretaceous Gobi coupled with the oological similarities between the Haţeg and Auca Mahuevo oological material evidence that several titanosaur species migrated from Gondwana through the Haţeg Island before or during the Aptian/Albian. It also suggests that this island might have had episodic land bridges with the rest of the European archipelago and Asia deep into the Cretaceous.</p> </div

Ion mobility–mass spectrometry as a tool to investigate protein–ligand interactions

Ion mobility–mass spectrometry (IM-MS) is a powerful tool for the simultaneous analysis of mass, charge, size, and shape of ionic species. It allows the characterization of even low-abundant species in complex samples and is therefore particularly suitable for the analysis of proteins and their assemblies. In the last few years even complex and intractable species have been investigated successfully with IM-MS and the number of publications in this field is steadily growing. This trend article highlights recent advances in which IM-MS was used to study protein–ligand complexes and in particular focuses on the catch and release (CaR) strategy and collision-induced unfolding (CIU)

Critical Evaluation of Native Electrospray Ionization Mass Spectrometry for Fragment-Based Screening

Fragment-based screening presents a promising alternative to high-throughput screening and has gained great attention over the last years. So far, only a few studies discuss mass spectrometry as a screening technology for fragments. Here, we applied native electrospray ionization mass spectrometry (ESI-MS) for screening defined sets of fragments against four different target proteins. Fragments were selected from a primary screen conducted by thermal shift assay (TSA) and represent different binding categories. Our data show that beside specific complex formation, many fragments show extensive multiple binding as well as charge-state shifts. Both of these factors complicate automated data analysis and lower the attractiveness of native MS as a primary screening tool for fragments. A comparison of hits identified by native MS and TSA shows good agreement for two proteins. Furthermore, we discuss general obstacles including the determination of an optimal fragment concentration and the question of how to rank fragment hits according to their affinity. In conclusion, we consider native MS a highly valuable tool for the validation and deeper investigation of promising fragment hits rather than a method for primary screening

Consistent variation in yolk androgens in the Australian Brush-turkey, a species without sibling competition or parental care

Maternal hormones are an excellent pathway for the mother to influence offspring development, and birds provide exceptional opportunities to study these hormone-mediated maternal effects. Two dominant hypotheses about the function of yolk androgens in avian eggs concern maternal manipulation of sibling competition and post hatching paternal care. In megapodes, however, neither sibling competition nor post hatching parental care exists. Eggs are incubated by external heat sources, and chicks dig themselves out of their underground nest and live independently of their parents and their siblings. In this first study on egg androgens of such a megapode, the Australian Brush-turkey Alectura lathami, we found nevertheless substantial amounts of maternal androgens. Since size of the incubation mound, incubation temperature, egg size and laying date greatly vary in this species, we analysed variation in testosterone (T), androstenedione (A4) and dihydrotestosterone (DHT) in relation to these factors. T concentrations were significantly higher in eggs from bigger mounds and laid at greater depth, which may compensate via anabolic effects for the longer duration and higher energetic requirements of chicks when digging themselves out. T concentrations were higher in smaller eggs, and both yolk A4 and T concentrations increased with laying date, perhaps as a compensatory measure, while DHT concentrations only varied across different mounds. These results indicate that maternal androgens may influence offspring development outside the contexts of sibling competition or parental care.

Presynaptic Calmodulin targets: lessons from structural proteomics

Introduction: Calmodulin (CaM) is a highly conserved Ca2+-binding protein that is exceptionally abundant in the brain. In the presynaptic compartment of neurons, CaM transduces changes in Ca2+ concentration into the regulation of synaptic transmission dynamics. Areas covered: We review selected literature including published CaM interactor screens and outlineestablished and candidate presynaptic CaM targets. We present a workflow of biochemical andstructural proteomic methods that were used to identify and characterize the interactions between CaM and Munc13 proteins. Finally, we outline the potential of ion mobility-mass spectrometry (IM-MS) for conformational screening and of protein-protein cross-linking for the structural characterization of CaM complexes. Expert commentary: Cross-linking/MS and native MS can be applied with considerable throughput to protein mixtures under near-physiological conditions, and thus effectively complement high-resolution structural biology techniques. Experimental distance constraints are applicable best when obtained by combining different cross-linking strategies, i.e. by using cross-linkers with different spacer length and reactivity, and by using the incorporation of unnatural photo-reactive amino acids. Insights from structural proteomics can be used to generate CaM-insensitive mutants of CaM targets for functional studies in vitro or ideally in vivo

To Anion–π or not to Anion–π: The Case of Anion‐Binding to Divalent Fluorinated Pyridines in the Gas Phase

Aseries of mono- and divalent fluorinatedpyri- dine derivatives is investigated by electrospray ionization (tandem) mass spectrometry and quantum chemical calcula- tions with respect to their capability to bind anions in the gas phase. The pyrid ine derivativ es differ not only in valency , but also with regard to the degree of fluorination of the pyr- idine rings, the positions of the fluorine atoms, the rigidity of the spacers connec ting the two pyridines in the divalent compounds, and the relative configuratio n. While the mono- valent compounds did not form anioncomplexes, the diva- lent analoguesexhibit anion binding even to weakly coordi- nating anionssuch as tetrafluoroborate.Three different tandem mass spectrometric experimentswereappliedto rank the gas-phase binding energies:(i) collision-induceddis- sociation (CID)experiments in aFourier transform ion-cyclo- tron-resonance (FTICR) mass spectrometer on two different, simultaneously mass-selected complexes with different re- ceptors, (ii)determination of the collisionenergy required to fragment 50 %ofthe mass-selected complexes in an ESI- QToF mass spectrometer,and (iii)CID of heterodimers formed from two different, competing pyridine receptor s and indigo carmine,adianionwith two identical binding sites. All three experimentsresult in consistent binding energyranking. This ranki ng reveals surprising features, whichare not in agreement with binding through anion–p interactions. Densityfunctionaltheory (DFT) calculations comparing different potentialbinding modes provide evi- dencethat the ranking can insteadnicely be explained, when C@H···anion interactions with the spacers are invoked. Theseresults are supported by gas-phase IR spectroscopy and ion mobility-mass spectrometry (IM-MS)onaselected set of chloridepyridine comp lexes