Back to Water: Signature of Adaptive Evolution in Cetacean Mitochondrial tRNAs

Abstract The mitochondrion is the power plant of the eukaryotic cell, and tRNAs are the fundamental components of its translational machinery. In the present paper, the evolution of mitochondrial tRNAs was investigated in the Cetacea, a clade of Cetartiodactyla that retuned to water and thus had to adapt its metabolism to a different medium than that of its mainland ancestors. Our analysis focussed on identifying the factors that influenced the evolution of Cetacea tRNA double-helix elements, which play a pivotal role in the formation of the secondary and tertiary structures of each tRNA and consequently manipulate the whole translation machinery of the mitochondrion. Our analyses showed that the substitution pathways in the stems of different tRNAs were influenced by various factors, determining a molecular evolution that was unique to each of the 22 tRNAs. Our data suggested that the composition, AT-skew, and GC-skew of the tRNA stems were the main factors influencing the substitution process. In particular, the range of variation and the fluctuation of these parameters affected the fate of single tRNAs. Strong heterogeneity was observed among the different species of Cetacea. Finally, it appears that the evolution of mitochondrial tRNAs was also shaped by the environments in which the Cetacean taxa differentiated. This latter effect was particularly evident in toothed whales that either live in freshwater or are deep divers

River loads of freshwater and nutrients in the continental shelf area of the Northern Adriatic Sea

River discharges have a great effect on oceanographic properties and production processes in the marine ecosystem of the Northern Adriatic Sea. The combination between meteorological forcings and the spreading of river waters, mainly from the Po River, determine formation and dynamics of the coastal fronts in the Western and Northern part of this continental shelf area, through the generation of alternated vertical and horizontal density gradients that drive the circulation of surface waters and the pattern of Southward flowing West Adriatic Current. High inputs of river borne nutrients sustain the peaks of production in this marine system, in particular during spring and autumn. However, they may also cause hypoxic or anoxic crises in the deeper waters, in case of weak circulation. Strong density gradients coupled to alternate ambient conditions experienced by plankton communities in the coastal area, due to the dynamics of low and high salinity waters, are also at the basis of dystrophic events that have often occurred in this area, such as the appearance of large dinoflagellate blooms and mucilage phenomenon. Despite its basic importance, the role of river loads in the Northern Adriatic Sea has been poorly studied, to date. A number of studies were published in the literature, mostly for Po and Adige rivers, as a result of the efforts addressed to the mitigation of eutrophication problems in the coastal zones carried out during the 1970\u27 and the 1980\u27, while the comparison of river loads at sub-regional scale still remains largely incomplete. In the framework of VECTOR research project (sub-task 6.1.3. Compilation of river load data, loads of nutrients and dissolved and particulate organic matter), the analysis of the current importance of river discharges in the Northern Adriatic Sea has been carried out, as a part of the study of carbon biogeochemical cycle in this basin, taking in account monitoring data provided by several environmental agencies and scientific institutions of Italy, Slovenia and Croatia. From 2004 to 2007, water load by Po River (20.54 - 45.30 km3y-1) constituted, on the average, 66% of the total river load in the basin, Adige River (10%), Brenta River (7%) and Livenza River (6%) being the other important sources of freshwater. Despite Po is an highly significant proxy of the total river load in the Northern Adriatic, the inputs from the rivers located along the Northern and Eastern sections of the coast were not negligible (11 and 6% of the total, respectively) and often not in phase with the regime of Po River. As shown by distinct peaks of discharge and by prolonged drought periods that often occurred in the minor rivers differently from Po River, because of their more pronounced flashy flow regimes. During the same years, total nitrogen (86,000 - 262,000 t N y-1) and total phosphorus (3,840 - 9,500 t P y-1) loads of Po River were highly variable, mainly as a consequence of the oscillations of annual integrated water discharges. The transport of TN and TP was constituted by dissolved inorganic nitrogen for 69% and by reactive phosphorus for 47%, whereas a high load of reactive silicon was also estimated (64,400 - 137,500 t Si y-1). The rivers located in the Northern and Eastern areas of the coast contributed respectively for 8% and 4% to the total load of TN in the basin, but only for 4% and 1% to the total load of TP. This finding pointed out that the strong decreasing gradient from West to East of nutrient supply in the Northern Adriatic might be further exacerbated in case of a selective reduction of the flows of minor rivers, due to oncoming natural changes or to larger anthropogenic usage of the continental waters. River loads estimated in this study do not strongly differ from the available data published in the scientific literature during the last decades, but they showed that the ecosystem of the Northern Adriatic Sea may experience a strong reduction (≈ -50%) of the supply of land borne nutrients during dry years, like in 2005. Recurring years characterised by extremely low discharges could have a great impact on the biogeochemistry of the whole Northern Adriatic basin

Prevalence of Golden retriever in European dogs with lymphoma: preliminary data

Introduction. Canine breeds, being genetic clusters, are good models for studies on genetic predisposition. Golden retriever (GR) has been described with a high incidence of both lymphoma overall (19%) and T zone lymphoma (TZL, 40%) with differences in different geographical areas in US. This breed predisposition is confirmed in Japanese but not in European (EU) case series although specific studies are still lacking.Aim of the present study is to investigate the prevalence of GR in a huge case series of canine lymphomas from different EU countries and to compare prevalence of different subtypes with studies in extra-EU countries, in order to support a possible different genetic predisposition.Materials and methods. Signalment data on 1734 consecutive cases of canine lymphoma collected from 9 different European countries are retrospectively analysed. When subtypes are available, cases are furtherly separated in three subtype groups: 1) B-cell lymphoma, 2) T-cell lymphoma-high grade, 3) TZL. Odds ratio (OR) for different lymphoma subtypes are calculated in comparison with mixed breed population, considered as control.Results. Overall prevalence of GR is 5.19% (range 1.59-7.32%) of lymphoma cases and differs from that reported in American and Japanese caseloads. Prevalence slightly varies among EU countries and no subtypes predilection is found if compared with mixed breed. Concerning Italian cohort, GR is not predisposed to develop a lymphoma when normalized for the breed prevalence (OR=1.49, 95% confidence interval=0.87-2.55, p=0.14).Discussion. Prevalence of lymphoma in EU population of GR is much lower than that of US. No predisposition is identified in EU GR for TZL differently from US and Japan. Being genetic of European GR population quite different from American and Japanese ones this suggest a possible different genetic predisposition. Slight differences in GR lymphoma prevalence among European countries likely reflects different breed distribution rather than different genetic predisposition

Long-term dynamics of hypoxia and anoxia in the Emilia Romagna coastal zone (Northern Adriatic Sea)

The Northern Adriatic is a continental shelf area characterised by highly variable freshwater discharges and production events. Here, hypoxia and anoxia have occurred both in offshore areas and in coastal waters, at least since the beginning of 1900. Despite several biogeochemical studies are available, longterm analysis of their recurrence, triggering mechanisms and impact on marine environment may provide a tool for a better understanding of present evolution of this ecosystem. For this reason, a compilation of the information contained in the scientific literature on the occurrence on decadal scales of hypoxia and anoxia in the North Adriatic has been done, focusing in particular on the Emilia Romagna coastal zone. Time series of Po River discharges and meteorological data (air temperature, precipitation, wind intensity and direction) were analysed, together with oceanographic conditions, as triggering factors for this phenomenon in the area of interest. The occurrence of plankton blooms was also reported and evaluated. The characteristics of hypo-anoxic events in terms of extension, duration and diffusion were collected in order to distinguish local vs. regional events, shortlived vs. long-lasting events, and to evaluate space and temporal evolutionary trends. This analysis was carried out through the reconstruction of time series of bottom dissolved O2 distribution for the period 1982-2005 and by comparison with reported observations on the field. On this base, latitudinal diffusion of events was studied, as well as possible exchanges between coastal and offshore waters. Finally, the analysis of this historical dataset suggests an increase in short-lived events, located in shallow waters, but often repeated during the year, which cause a continuous stress on the pelagic and benthic habitats. This temporal trends may be related to regional changes of the climatic conditions, which include an higher frequency of irregular seasonal cycles

Importanza e distribuzione spazio-temporale delle frazioni organiche disciolte dell\u27azoto e fosforo nel bacino del nord Adriatico

The effects of continental inputs and biological processes acting on dissolved inorganic (DIN and DIP) and organic (DON and DOP) nitrogen and phosphorus are discussed in the North-western Adriatic Sea. The allocthonous contributions of DIN are evidenced, particularly in winter, in the mixed layer (up to 18 μmol-N?dm-3) while the other fractions of nitrogen and phosphorous show behaviours which depend more on the biological activity in the marine environment. The presented. data evidence the importance of DON and DOP which can constitute, in this basin, up to 93% and 96% of the available nitrogen and phosphorus, respectively. Moreover, the phosphorus deficiency, when compared to nitrogen, has been evidenced not only in the inorganic fraction (DIN/DIP ratios from 25 up to 3000) but also in the organic fraction(DON/DOP ratios from 50 up to 1500). At last, spatial and seasonal trends of these parameters suggest the uncoupling between these nutrients and indicate a faster recycling of phosphorus with respect to nitrogen through the biological compartments of the ecosystem

First basin-wide experimental results on N2-fixation in the open Mediterranean Sea.

Mediterranean Sea presents several biogeochemical anomalies compared to the global ocean. Unbalanced N budget, high nitrate/phosphate ratios in subsurface waters and light isotopic signals in particulate and dissolved nitrogen have suggested a relevant occurrence of N2-fixation. This study presents, for the first time, N2-fixation rate measurements in the open Mediterranean Sea on a basin scale during early summer, compared to one site in the North Atlantic. Very low rates (0.052?0.031 nmols N l-1d-1) were observed in all sub-regions of the Mediterranean, unlike the higher values measured in the North Atlantic surface waters (0.300?0.115 nmols N l-1d-1). No evidence of phosphate limitation emerges from this study. Low N2-fixation rates associated to light isotopic composition of PON (from -2.10 to 4.11?) suggest that other light N sources, different from atmospheric N2, fuel the Mediterranean ecosystem

New observations of CO2 - induced acidification in the northern Adriatic Sea.

In the Mediterranean area the North Adriatic is one of the most suitable sites for studying the response of marine pH to increased atmospheric CO2 levels because of its shallow depth and being exposed to strong cold winds during winter. During VECTOR VECSES 1 cruise (15 to 19 February 2008), pH and total alkalinity (AT) were measured over the North Adriatic basin. These data were compared with that collected during ASCOP 2 cruise (30 April to 8 May 1983), 25 years before. During ASCOP 2 cruise pH was determined at 25 ?C using a potentiometric method in NBS scale (pHNBS) while during VECSES 1 cruise it was measured by the spectrophotometric method (precision ? 0.003) and the results expressed on "total scale" at 25?C (pHT). To allow a comparison the pHNBS values were converted into the total scale and the reliability of the conversion was checked. Comparable North Adriatic dense water bodies were identified according to T, S and AOU data from both the datasets and the carbonate system parameters were compared. Results at 25?C showed an acidification of -0.063 pHT units from 1983 and 2008 and a decrease in carbonate ion concentration (-19.6Qmol kg-1), whereas total alcalinity (+ 74 Qmol kg-1), dissolved inorganic carbon (+ 110 Qmol kg-1) and CO2 (+ 108 Q atm) exhibited a net increase over the same period. The drivers of these changes were analyzed and the increase in atmospheric CO2 concentration was identified as the main forcing that determined the acidification observed. It would correspond to an acidification rate of -0.0025 pH units/year, that is of the same order of magnitude of the rate measured in other oceanic regions. This study, even if it was based on the comparison of only two datasets spanning 25 years is the first published work (Luchetta et al., Chem. and Ecol., 2010, vol. 26, 1-17) assessing the ocean acidification process in the Mediterranean region and one of the few based on the analysis of experimental data

Distributions of pHT, total alkalinity and CO2 fugacity in the Adriatic Sea during the SESAME campaigns, winter and late summer 2008. CIESM

pH experimental data of good quality are still scarce in the Mediterranean as in the Adriatic Sea. Here are presented the results of two repeated surveys at basin scale, conducted within SESAME project, showing significant longitudinal and seasonal variabilities of the pH and other carbonate system parameters

Toward an assessment of ocean acidification in the Adriatic sea and its impact on the biogeochemistry of marine carbonate system

The increase of CO2 amount in the atmosphere has created great concern: it will in all probability result in changes in temperature, precipitation and/or their seasonal amplitudes with consequences not only on sea level rise but also on chemical equilibrium of the CO2 system in seawater, mainly reducing pH and carbonate ion concentration (Ocean Acidification). The process is now well documented in field data from all around the world. However is not sufficiently witnessed in the Mediterreranean Sea, due to the scarcity of good quality data. On this concern, results for the Adriatic Sea are presented: from experimental measures of pH and total alkalinity, two seasonal pictures of pH and carbonate system parameters have been drawn. In addition, a pH decrease of 0.063 pHT units with related chemistry changes has been inferred in the North Adriatic Dense Water (NAdDW) over the two last decades. These results, although preliminary, merit attention as confirm that N. A. sea has been affected by OA, being sensitive to the climate forcing. Potential impacts of OA are several and should be assessed, as many might even exacerbate hyopoxia/anoxia events, already affecting the area. OA might also affetc the food web, as the carbonate reduction has the potential to alter the distribution and abundance of marine organisms that use calcium carbonate to build their shells or skeletons (corals, plankton) and the organisms that depend on them for survival (fishes, marine mammals)