Rapid Divergent Evolution of Male Genitalia Among Populations of Drosophila buzzatii

Increasing evidence from multiple animal systems suggests that genital evolution and diversification are driven by rapid and strong evolutionary forces. Particularly, the morphology of male genital structures is considered to be among the fastest evolving traits in animal groups with internal fertilization. In this study, we investigated patterns of male genital variation within and between natural populations of the cactophilic fly Drosophila buzzatii in its original geographic distribution range in the Neotropics. We detected significant morphological differences among populations and distinguished five differentiated groups. Moreover, among population differentiation in genital morphology was associated with the degree of geographic isolation among populations and clearly contrasted with the general homogeneity detected for the putatively neutral mitochondrial gene COI. Integrating our present data with previous molecular population genetic surveys, our results suggest that male genital morphology has rapidly diverged after the recent demographic expansion that D. buzzatii has undergone in the arid zones of South America. Because the “lock and key” hypothesis failed to explain the present pattern, we explored alternative explanations for the observed pattern of genital diversification including drift-facilitated sexual selection.     

A new small mammal assemblage from the M013 Terre Rosse fissure filling (Gargano,South-Eastern Italy)

The taxonomic study of the small mammal assemblage from fissure M013, sampled by a team of the University of Torino during the 2005–2009 excavations in the Dell’Erba Quarry (Apricena, Foggia) is presented. The assemblage includes the Echinosoricinae Apulogalerix cf. pusillus and the Crocidosoricinae ?Lartetium cf. dehmi; the Myomiminae species Stertomys simplex and Stertomys lyrifer; a new genus and species of Cricetodontinae and a single specimen of Hattomys cf. nazarii. Muridae include Mikrotia cf. parva, Mikrotia sp. 1 and a new genus and species of Murinae, phylogenetically related to Mikrotia. The occurrence of the new Murinae, the new Cricetodontinae, the two species of glirids and the Crocidosoricinae, as well as the absence of Apodemus and Prolagus, indicates M013 as the oldest Gargano's faunal assemblage known to date, despite the occurrence of Hattomys cf. nazarii, Mikrotia cf. parva and Mikrotia sp. 1, which most probably results from infiltrations from younger fissure fillings. The M013 assemblage is an absolute novelty for the Abruzzo-Apulian Palaeobioprovince, opening new perspectives for the timing and mode of dispersal of the forerunners of the Gargano fauna.     

Spatial variability of chlorophyll-a and abiotic variables in a river–floodplain system during different hydrological phases

Chlorophyll-a (Chl-a) and abiotic variables were measured in the main channel and floodplain waterbodies of the Middle Paraná River to analyse the system dynamics and to assess their spatial variability during different hydrological phases, including an extreme flood. We wanted to test that the flood does not always have a homogenising effect in a river–floodplain system. An explanatory model for Chl-a was performed according to Akaike’s Information Criterion (AIC), and the relation of water level with the coefficient of variation (CV) among sites for each variable was explored. The model explained 64% of Chl-a variability. Water level, depth:euphotic zone ratio (Z _d:Z _eu) (inverse correlation) and conductivity (direct correlation) were the significant explicative variables. The CV of Chl-a decreased with flood from the main channel to the floodplain, but for turbidity, Z _d:Z _eu, pH, dissolved oxygen, soluble reactive phosphorus and Chl-a:pheophytin-a ratio, it increased. However, within the floodplain, CV of turbidity, Z _d:Z _eu and pH decreased during flood. These suggest that the homogenising effect frequently observed during inundation cannot be generalised and that the floodplain may maintain its identity even during flood. The extreme flood and its overlap with the warm season and sedimentological pulse probably contributed to the heterogeneity in the spatial gradient.     

Fluorescent ligands for adenosine receptors

Interest is increasing in developing fluorescent ligands for characterization of adenosine receptors (ARs), which hold a promise of usefulness in the drug discovery process. The size of a strategically labeled AR ligand can be greatly increased after the attachment of a fluorophore. The choice of dye moiety (e.g. Alexa Fluor 488), attachment point and linker length can alter the selectivity and potency of the parent molecule. Fluorescent derivatives of adenosine agonists and antagonists (e.g. XAC and other heterocyclic antagonist scaffolds) have been synthesized and characterized pharmacologically. Some are useful AR probes for flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer, and scanning confocal microscopy. Thus, the approach of fluorescent labeled GPCR ligands, including those for ARs, is a growing dynamic research field.     

Presence of osteoinductive factors in bovine colostrum

New approaches in the treatment of skeletal defects may benefit from the use of soluble biological factors. We previously standardized a derivative of bovine colostrum (SBCD), deprived of casein and fat and rich in cytokines. In the present study, we tested its possible use as an adjuvant in bone healing. SBCD contained factors involved in stromal cell stimulation and differentiation and induced cytokine production from stimulated mesenchymal stem cells (MSCs). In vitro, SBCD promoted proliferation, migration and, in association with osteogenic factors, osteogenic differentiation of osteoblastic and MSCs. In in vivo experiments of subcutaneous Matrigel injection in mice, SBCD plus hydroxyapatite, but not hydroxyapatite nor SBCD alone, induced recruitment of macrophages and stromal cells. After 60?days, plugs containing SBCD and hydroxyapatite were densely calcified and diffusely positive for osteocalcin, supporting the occurrence of an early osteogenic process. These results indicate that SBCD is a rich source of factors with osteoinductive properties.     

Atrioventricular nodal function during atrial fibrillation: Model building and robust estimation

Statistical modeling of atrioventricular (AV) nodal function during atrial fibrillation (AF) is revisited for the purpose of defining model properties and improving parameter estimation. The characterization of AV nodal pathways is made more detailed and the number of pathways is now determined by the Bayesian information criterion, rather than just producing a probability as was previously done. Robust estimation of the shorter refractory period (i.e., of the slow pathway) is accomplished by a Hough-based technique which is applied to a Poincaré plot of RR intervals. The performance is evaluated on simulated data as well as on ECG data acquired from AF patients during rest and head-up tilt test. The simulation results suggest that the refractory period of the slow pathway can be accurately estimated even in the presence of many artifacts. They also show that the number of pathways can be accurately determined. The results from ECG data show that the refined AV node model provides significantly better fit than did the original model, increasing from 85 ± 5% to 88 ± 4% during rest, and from 86 ± 5% to 87 ± 3% during tilt. When assessing the effect of sympathetic stimulation, the AF frequency increased significantly during tilt (6.25 ± 0.58 Hz vs. 6.32 ± 0.61 Hz, p < 0.05, rest vs. tilt) and the prolongation of the refractory periods of both pathways decreased significantly (slow pathway: 0.23 ± 0.20 s vs. 0.11 ± 0.10 s, p < 0.001, rest vs. tilt; fast pathway: 0.24 ± 0.31 s vs. 0.16 ± 0.19 s, p < 0.05, rest vs. tilt). The results show that AV node characteristics can be assessed noninvasively for the purpose of quantifying changes induced by autonomic stimulation.     

Metagenomic insights into strategies of carbon conservation and unusual sulfur biogeochemistry in a hypersaline Antarctic lake

Organic Lake is a shallow, marine-derived hypersaline lake in the Vestfold Hills, Antarctica that has the highest reported concentration of dimethylsulfide (DMS) in a natural body of water. To determine the composition and functional potential of the microbial community and learn about the unusual sulfur chemistry in Organic Lake, shotgun metagenomics was performed on size-fractionated samples collected along a depth profile. Eucaryal phytoflagellates were the main photosynthetic organisms. Bacteria were dominated by the globally distributed heterotrophic taxa Marinobacter, Roseovarius and Psychroflexus. The dominance of heterotrophic degradation, coupled with low fixation potential, indicates possible net carbon loss. However, abundant marker genes for aerobic anoxygenic phototrophy, sulfur oxidation, rhodopsins and CO oxidation were also linked to the dominant heterotrophic bacteria, and indicate the use of photo- and lithoheterotrophy as mechanisms for conserving organic carbon. Similarly, a high genetic potential for the recycling of nitrogen compounds likely functions to retain fixed nitrogen in the lake. Dimethylsulfoniopropionate (DMSP) lyase genes were abundant, indicating that DMSP is a significant carbon and energy source. Unlike marine environments, DMSP demethylases were less abundant, indicating that DMSP cleavage is the likely source of high DMS concentration. DMSP cleavage, carbon mixotrophy (photoheterotrophy and lithoheterotrophy) and nitrogen remineralization by dominant Organic Lake bacteria are potentially important adaptations to nutrient constraints. In particular, carbon mixotrophy relieves the extent of carbon oxidation for energy production, allowing more carbon to be used for biosynthetic processes. The study sheds light on how the microbial community has adapted to this unique Antarctic lake environment.