Islands beneath islands: phylogeography of a groundwater amphipod crustacean in the Balearic archipelago

<p>Abstract</p> <p>Background</p> <p>Metacrangonyctidae (Amphipoda, Crustacea) is an enigmatic continental subterranean water family of marine origin (thalassoid). One of the species in the genus, <it>Metacrangonyx longipes</it>, is endemic to the Balearic islands of Mallorca and Menorca (W Mediterranean). It has been suggested that the origin and distribution of thalassoid crustaceans could be explained by one of two alternative hypotheses: (1) active colonization of inland freshwater aquifers by a marine ancestor, followed by an adaptative shift; or (2) passive colonization by stranding of ancestral marine populations in coastal aquifers during marine regressions. A comparison of phylogenies, phylogeographic patterns and age estimations of clades should discriminate in favour of one of these two proposals.</p> <p>Results</p> <p>Phylogenetic relationships within <it>M. longipes </it>based on three mitochondrial DNA (mtDNA) and one nuclear marker revealed five genetically divergent and geographically structured clades. Analyses of cytochrome oxidase subunit 1 (<it>cox1</it>) mtDNA data showed the occurrence of a high geographic population subdivision in both islands, with current gene flow occurring exclusively between sites located in close proximity. Molecular-clock estimations dated the origin of <it>M. longipes </it>previous to about 6 Ma, whereas major cladogenetic events within the species took place between 4.2 and 2.0 Ma.</p> <p>Conclusions</p> <p><it>M. longipes </it>displayed a surprisingly old and highly fragmented population structure, with major episodes of cladogenesis within the species roughly correlating with some of the major marine transgression-regression episodes that affected the region during the last 6 Ma. Eustatic changes (vicariant events) -not active range expansion of marine littoral ancestors colonizing desalinated habitats-explain the phylogeographic pattern observed in <it>M. longipes</it>.</p

Amphipathic polymers enable the study of functional membrane proteins in the gas phase

Membrane proteins are notoriously challenging to analyze using mass spectrometry (MS) because of their insolubility in aqueous solution. Current MS methods for studying intact membrane proteins involve solubilization in detergent. However, detergents can destabilize proteins, leading to protein unfolding and aggregation, or resulting in inactive entities. Amphipathic polymers, termed amphipols, can be used as a substitute for detergents and have been shown to enhance the stability of membrane proteins. Here, we show the utility of amphipols for investigating the structural and functional properties of membrane proteins using electrospray ionization mass spectrometry (ESI-MS). The functional properties of two bacterial outer-membrane β-barrel proteins, OmpT and PagP, in complex with the amphipol A8-35 are demonstrated, and their structural integrities are confirmed in the gas phase using ESI-MS coupled with ion mobility spectrometry (IMS). The data illustrate the power of ESI-IMS-MS in separating distinct populations of amphipathic polymers from the amphipol-membrane complex while maintaining a conformationally "nativelike" membrane protein structure in the gas phase. Together, the data indicate the potential importance and utility of amphipols for the analysis of membrane proteins using MS

The impact of economic recession on company activities

Negative consequences of economic fluctuations and economic downturns influence the significance of research in this area. Results of such research allow providing insights and sugges¬tions for governments to make political-economic decisions. The article investigates the impact of slowing economy on enterprises, the reasons of fluctuations of economic cycles and their characteristics, phases of economic cycle: growth, peak, downturn and crisis. The article studies definition of slowing economy, its reasons, ratios, and inter-relationship between various ratios. Methodology of evaluating economic cycles is provided in the article. Article in Lithuanian. Lėtėjančios ekonomikos poveikis įmonių veiklai Santrauka&nbsp; Didėjantys neigiami ekonominių svyravimų ir ekonomikos nuosmukio padariniai nulemia šioje srityje atliekamų tyrimų svarbą. Remiantis tyrimų rezultatais, pateikiamos įžvalgos ir pasiūlymai vyriausybės politiniams – ekonominiams sprendimams priimti. Straipsnyje nagrinėjamas lėtėjančios ekonomikos poveikis įmonėms, išgrynintos pagrindinės ekonomikos ciklų svyravimų priežastys ir jų charakteristikos. Nagrinėjamos ekonominio ciklo fazės: pakilimas, viršūnė, nuosmukis ir krizė. Analizuojama ekonomikos lėtėjimo samprata, priežastys, rodikliai ir įvairių ekonominių rodiklių sąveika. Taip pat pateikiama ekonominių ciklų vertinimo metodika. Reikšminiai žodžiai:&nbsp;ekonominiai ciklai, ciklo fazės, lėtėjimas, pakilimas, krizė, lėtėjimo rodikliai

THE IMPACT OF ECONOMIC RECESSION ON COMPANY ACTIVITIES / LĖTĖJANČIOS EKONOMIKOS POVEIKIS ĮMONIŲ VEIKLAI

Negative consequences of economic fluctuations and economic downturns influence the significance of research in this area. Results of such research allow providing insights and sugges¬tions for governments to make political-economic decisions. The article investigates the impact of slowing economy on enterprises, the reasons of fluctuations of economic cycles and their characteristics, phases of economic cycle: growth, peak, downturn and crisis. The article studies definition of slowing economy, its reasons, ratios, and inter-relationship between various ratios. Methodology of evaluating economic cycles is provided in the article. Santrauka  Didėjantys neigiami ekonominių svyravimų ir ekonomikos nuosmukio padariniai nulemia šioje srityje atliekamų tyrimų svarbą. Remiantis tyrimų rezultatais, pateikiamos įžvalgos ir pasiūlymai vyriausybės politiniams – ekonominiams sprendimams priimti. Straipsnyje nagrinėjamas lėtėjančios ekonomikos poveikis įmonėms, išgrynintos pagrindinės ekonomikos ciklų svyravimų priežastys ir jų charakteristikos. Nagrinėjamos ekonominio ciklo fazės: pakilimas, viršūnė, nuosmukis ir krizė. Analizuojama ekonomikos lėtėjimo samprata, priežastys, rodikliai ir įvairių ekonominių rodiklių sąveika. Taip pat pateikiama ekonominių ciklų vertinimo metodika. Reikšminiai žodžiai: ekonominiai ciklai, ciklo fazės, lėtėjimas, pakilimas, krizė, lėtėjimo rodikliai

The variation of stygofauna along a gradient of salinization in a coastal aquifer

We examined the variation of stygofauna composition collected in wells, along a gradient in groundwater salinity/conductivity in a coastal aquifer from southern Portugal. The studied coastal aquifer is considered vulnerable to salinization due to seawater intrusion, caused by overexploitation of the aquifer. Knowing the response of the stygofauna species to present levels of groundwater salinity makes it possible to understand and measure the effects of saltwater intrusion on stygofauna, rendering them potential bioindicators of this environmental pressure. Biotic and abiotic sampling was conducted in six shallow wells located in the fresh-saltwater interface of the Arade estuary along the salinity gradient established in the groundwater from the estuary to inland locations (microSiemens/cm). Groundwater salinity was highly correlated with taxa distribution. The stygobites Eucyclops hadjebensis and Acanthocyclops sensitivus, the cosmopolitan Megacyclops viridis and Cypria ophtalmica were particularly associated with low-salinity conditions, whereas Eucyclops graeteri, Megacyclops brachypus and Daphnia pulicaria were related to high-salinity waters. Multivariate analyses indicated that stygofauna assemblages varied significantly with location. We suggest that stygofauna composition and structure can be a useful complementing tool for monitoring seawater intrusion into coastal aquifers, where reduction or deterioration in groundwater resources is predicted

Amphipols outperform dodecylmaltoside micelles in stabilizing membrane protein structure in the gas phase

Noncovalent mass spectrometry (MS) is emerging as an invaluable technique to probe the structure, interactions, and dynamics of membrane proteins (MPs). However, maintaining native-like MP conformations in the gas phase using detergent solubilized proteins is often challenging and may limit structural analysis. Amphipols, such as the well characterized A8-35, are alternative reagents able to maintain the solubility of MPs in detergent-free solution. In this work, the ability of A8-35 to retain the structural integrity of MPs for interrogation by electrospray ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS) is compared systematically with the commonly used detergent dodecylmaltoside. MPs from the two major structural classes were selected for analysis, including two β-barrel outer MPs, PagP and OmpT (20.2 and 33.5 kDa, respectively), and two α-helical proteins, Mhp1 and GalP (54.6 and 51.7 kDa, respectively). Evaluation of the rotationally averaged collision cross sections of the observed ions revealed that the native structures of detergent solubilized MPs were not always retained in the gas phase, with both collapsed and unfolded species being detected. In contrast, ESI-IMS-MS analysis of the amphipol solubilized MPs studied resulted in charge state distributions consistent with less gas phase induced unfolding, and the presence of lowly charged ions which exhibit collision cross sections comparable with those calculated from high resolution structural data. The data demonstrate that A8-35 can be more effective than dodecylmaltoside at maintaining native MP structure and interactions in the gas phase, permitting noncovalent ESI-IMS-MS analysis of MPs from the two major structural classes, while gas phase dissociation from dodecylmaltoside micelles leads to significant gas phase unfolding, especially for the α-helical MPs studied