The Effects of Anthropogenic Structures on Habitat Connectivity and the Potential Spread of Non-Native Invertebrate Species in the Offshore Environment

Offshore structures provide habitat that could facilitate species range expansions and the introduction of non-native species into new geographic areas. Surveys of assemblages of seven offshore oil and gas platforms in the Santa Barbara Channel revealed a change in distribution of the non-native sessile invertebrate Watersipora subtorquata, a bryozoan with a planktonic larval duration (PLD) of 24 hours or less, from one platform in 2001 to four platforms in 2013. We use a three-dimensional biophysical model to assess whether larval dispersal via currents from harbors to platforms and among platforms is a plausible mechanism to explain the change in distribution of Watersipora and to predict potential spread to other platforms in the future. Hull fouling is another possible mechanism to explain the change in distribution of Watersipora. We find that larval dispersal via currents could account for the increase in distribution of Watersipora from one to four platforms and that Watersipora is unlikely to spread from these four platforms to additional platforms through larval dispersal. Our results also suggest that larvae with PLDs of 24 hours or less released from offshore platforms can attain much greater dispersal distances than larvae with PLDs of 24 hours or less released from nearshore habitat. We hypothesize that the enhanced dispersal distance of larvae released from offshore platforms is driven by a combination of the offshore hydrodynamic environment, larval behavior, and larval release above the seafloor.     

Worldwide Alien Invasion: A Methodological Approach to Forecast the Potential Spread of a Highly Invasive Pollinator

The ecological impacts of alien species invasion are a major threat to global biodiversity. The increasing number of invasion events by alien species and the high cost and difficulty of eradicating invasive species once established require the development of new methods and tools for predicting the most susceptible areas to invasion. Invasive pollinators pose serious threats to biodiversity and human activity due to their close relationship with many plants (including crop species) and high potential competitiveness for resources with native pollinators. Although at an early stage of expansion, the bumblebee species Bombus terrestris is becoming a representative case of pollinator invasion at a global scale, particularly given its high velocity of invasive spread and the increasing number of reports of its impacts on native bees and crops in many countries. We present here a methodological framework of habitat suitability modeling that integrates new approaches for detecting habitats that are susceptible to Bombus terrestris invasion at a global scale. Our approach did not include reported invaded locations in the modeling procedure; instead, those locations were used exclusively to evaluate the accuracy of the models in predicting suitability over regions already invaded. Moreover, a new and more intuitive approach was developed to select the models and evaluate different algorithms based on their performance and predictive convergence. Finally, we present a comprehensive global map of susceptibility to Bombus terrestris invasion that highlights priority areas for monitoring.     

Potential fitness benefits from mate selection in the Atlantic cod (Gadus morhua)

Little evidence of benefits from female mate choice has been found when males provide no parental care or resources. Yet, good genes models of sexual selection suggest that elaborated male sexual characters are reliable signals of mate quality and that the offspring of males with elaborate sexual ornaments will perform better than those of males with less elaborate ornaments. We used cod (Gadus morhua L.), an externally fertilizing species where males provide nothing but sperm, to examine the potential of optimal mate selection with respect to offspring survival. By applying in vitro fertilizations, we crossed eight females with nine males in all possible combinations and reared each of the 72 sib groups. We found that offspring survival was dependent on which female was mated with which male and that optimal mate selection has the potential to increase mean offspring survival from 31.9 to 55.6% (a 74% increase). However, the size of the male sexual ornaments and sperm quality (i.e. sperm velocity and sperm density) could not predict offspring survival. Thus, even if there may be large fitness benefits of mate selection, we might not yet have identified the male characteristics generating high offspring survival.     

Analysis of the Temporal Organization of Sleep Spindles in the Human Sleep EEG Using a Phenomenological Modeling Approach

The sleep electroencephalogram (EEG) is characterized by typical oscillatory patterns such as sleep spindles and slow waves. Recently, we proposed a method to detect and analyze these patterns using linear autoregressive models for short (≈?1 s) data segments. We analyzed the temporal organization of sleep spindles and discuss to what extent the observed interevent intervals correspond to properties of stationary stochastic processes and whether additional slow processes, such as slow oscillations, have to be assumed. We have found evidence for such an additional slow process, most pronounced in sleep stage 2.     

Molecular cloning and characterization of rhodopsin in a teleost (Plecoglossus altivelis,Osmeridae)

Amplified fragments encoding exon-4 of opsin cDNAs were cloned from the retina of landlocked ayu (Plecoglossus altivelis), and sequenced. On the basis of the sequence homology to previously characterized fish visual pigments, one clone was identified as rod opsin (AYU-Rh), and two clones as green (AYU-G1, -G2), one as red (AYU-R) and two as ultraviolet (AYU-UV1, -UV2) cone opsins. The 335-amino acid sequence deduced from the full-length cDNA of AYU-Rh included residues highly conserved in vertebrate rhodopsins and showed the greatest degree (88%) of similarity with salmon rhodopsin. Southern blotting analysis indicated that ayu possess two rhodopsin genes, one encoding visual rhodopsin (AYU-Rh) and the other non-visual extra-ocular rhodopsin (AYU-ExoRh). RT-PCR experiments revealed that AYU-Rh was expressed in the retina and AYU-ExoRh in the pineal gland. In situ hybridization experiments showed that the mRNA of AYU-Rh was localized only in rod cells not in cone cells. Lake and river type landlocked ayu having different amounts of retinal and 3-hydroxyretinal in their retinas expressed a rhodopsin (AYU-Rh) of identical amino acid sequence.     

Song Variation in a Recently Founded Population of the Dark-Eyed Junco (Junco hyemalis)

During natural colonization events, songs are expected to change as a result of both selection and drift-like processes. We studied song variation within a small isolated population of dark-eyed juncos, Junco hyemalis , which became established in an unusual environment on the University of California at San Diego (UCSD) campus in the early 1980's, and compared this variation with the native range. At UCSD, the average repertoire size is 4.2 song types/male, which is similar to that in the native range. There is a low level of song-type sharing across the population. Typically a male shares at least one song type with on average 40% of his neighbors, and song-type sharing decreases rapidly with distance. Thus song-type diversity is high, and in this respect appears similar to that in ancestral mountain populations. These results suggest a moderate to large number of males founded and/or subsequently immigrated into the UCSD population, but several selection mechanisms, if coupled with a high cultural mutation rate, may also favor high song-type diversity. When combined with results from a previous study, songs are significantly shorter at UCSD than in the mountain population we studied. It appears that founder effects have not influenced the evolution of songs in this population. More generally, if song-type diversity and other features of song result from various social and natural selection pressures, many of these pressures may have remained similar between the native and the recently established population.     

Approach for Qualitative Validation Using Aggregated Data for a Stochastic Simulation Model of the Spread of the Bovine Viral-Diarrhoea Virus in a Dairy Cattle Herd

Qualitative validation consists in showing that a model is able to mimic available observed data. In population level biological models, the available data frequently represent a group status, such as pool testing, rather than the individual statuses. They are aggregated. Our objective was to explore an approach for qualitative validation of a model with aggregated data and to apply it to validate a stochastic model simulating the bovine viral-diarrhoea virus (BVDV) spread within a dairy cattle herd. Repeated measures of the level of BVDV-specific antibodies in the bulk-tank milk (total milk production of a herd) were used to summarise the BVDV herd status. First, a domain of validation was defined to ensure a comparison restricted to dynamics of pathogen spread well identified among observed aggregated data (new herd infection with a wide BVDV spread). For simulations, scenarios were defined and simulation outputs at the individual animal level were aggregated at the herd level using an aggregation function. Comparison was done only for observed data and simulated aggregated outputs that were in the domain of validation. The validity of our BVDV model was not rejected. Drawbacks and ways of improvement of the approach are discussed.     

Mathematical Modeling of the Effectiveness of Facemasks in Reducing the Spread of Novel Influenza A (H1N1)

On June 11, 2009, the World Health Organization declared the outbreak of novel influenza A (H1N1) a pandemic. With limited supplies of antivirals and vaccines, countries and individuals are looking at other ways to reduce the spread of pandemic (H1N1) 2009, particularly options that are cost effective and relatively easy to implement. Recent experiences with the 2003 SARS and 2009 H1N1 epidemics have shown that people are willing to wear facemasks to protect themselves against infection; however, little research has been done to quantify the impact of using facemasks in reducing the spread of disease. We construct and analyze a mathematical model for a population in which some people wear facemasks during the pandemic and quantify impact of these masks on the spread of influenza. To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks. The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%. We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009.     

Peptide NMHRYPNQ of the Cellular Prion Protein (PrP) Inhibits Aggregation and Is a Potential Key for Understanding Prion-Prion Interactions

Pathogenesis of transmissible spongiform encephalopathies is correlated with a conversion of the normal cellular form of the prion protein (PrP^C) into the abnormal isoform (scrapie form of PrP). Contact of the normal PrP with its abnormal isoform, the scrapie form of PrP, induces the transformation. Knowledge of molecules that inhibit such contacts leads to an understanding of the mechanism of the aggregation, and these molecules may serve as leads for drugs against transmissible spongiform encephalopathies. Therefore, we screened a synthetic octapeptide library of the globular domain of the human PrP^C for binding affinity to PrP^C. Two fragments with binding affinity, 149YYRENMHR156 and 153NMHRYPNQ160, were identified with K_d values of 21 and 25 μM, respectively. A 10-fold excess of peptide 153NMHRYPNQ160 inhibits aggregation of the PrP by 99%. NMR and mass spectrometry showed that the binding region of the peptide 153NMHRYPNQ160 is located at helix 3 of the PrP.     

Activity Response to Climate Seasonality in Species with Fossorial Habits: A Niche Modeling Approach Using the Lowland Burrowing Treefrog (Smilisca fodiens)

The importance of climatic conditions in shaping the geographic distribution of amphibian species is mainly associated to their high sensitivity to environmental conditions. How they cope with climate gradients through behavioral adaptations throughout their distribution is an important issue due to the ecological and evolutionary implications for population viability. Given their low dispersal abilities, the response to seasonal climate changes may not be migration, but behavioral and physiological adaptations. Here we tested whether shifts in climatic seasonality can predict the temporal variation of surface activity of the fossorial Lowland Burrowing Treefrog (Smilisca fodiens) across its geographical distribution. We employed Ecological Niche Modeling (ENM) to perform a monthly analysis of spatial variation of suitable climatic conditions (defined by the July conditions, the month of greatest activity), and then evaluated the geographical correspondence of monthly projections with the occurrence data per month. We found that the species activity, based on the species'' occurrence data, corresponds with the latitudinal variation of suitable climatic conditions. Due to the behavioral response of this fossorial frog to seasonal climate variation, we suggest that precipitation and temperature have played a major role in the definition of geographical and temporal distribution patterns, as well as in shaping behavioral adaptations to local climatic conditions. This highlights the influence of macroclimate on shaping activity patterns and the important role of fossorials habits to meet the environmental requirements necessary for survival.     

Mapping the Potential Risk of Mycetoma Infection in Sudan and South Sudan Using Ecological Niche Modeling

In 2013, the World Health Organization (WHO) recognized mycetoma as one of the neglected tropical conditions due to the efforts of the mycetoma consortium. This same consortium formulated knowledge gaps that require further research. One of these gaps was that very few data are available on the epidemiology and transmission cycle of the causative agents. Previous work suggested a soil-borne or Acacia thorn-prick-mediated origin of mycetoma infections, but no studies have investigated effects of soil type and Acacia geographic distribution on mycetoma case distributions. Here, we map risk of mycetoma infection across Sudan and South Sudan using ecological niche modeling (ENM). For this study, records of mycetoma cases were obtained from the scientific literature and GIDEON; Acacia records were obtained from the Global Biodiversity Information Facility. We developed ENMs based on digital GIS data layers summarizing soil characteristics, land-surface temperature, and greenness indices to provide a rich picture of environmental variation across Sudan and South Sudan. ENMs were calibrated in known endemic districts and transferred countrywide; model results suggested that risk is greatest in an east-west belt across central Sudan. Visualizing ENMs in environmental dimensions, mycetoma occurs under diverse environmental conditions. We compared niches of mycetoma and Acacia trees, and could not reject the null hypothesis of niche similarity. This study revealed contributions of different environmental factors to mycetoma infection risk, identified suitable environments and regions for transmission, signaled a potential mycetoma-Acacia association, and provided steps towards a robust risk map for the disease.     

Genetic characteristics of the amphidromous fish Ayu Plecoglossus altivelis altivelis (Osmeriformes: Plecoglossidae) on Yaku-shima Island in Japan,the southernmost population of the subspecies

Genetica - The Ayu (Plecoglossus altivelis altivelis) population on Yaku-shima Island, Kagoshima Prefecture, Japan represents the southernmost population of the subspecies and is considered to be...     

Homogenous Population Genetic Structure of the Non-Native Raccoon Dog (Nyctereutes procyonoides) in Europe as a Result of Rapid Population Expansion

The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides) in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species’ dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large ‘central’ population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.     

Pattern of synaptic connections in the pineal organ of the ayu,Plecoglossus altivelis (Teleostei)

Summary Synaptic connections were studied by means of electron microscopy in the sensory pineal organ of the ayu, Plecoglossus altivelis, a highly photosensitive teleost species. Three types of specific contacts were observed in the pineal end-vesicle: 1) symmetrically organized gap junctions between the basal processes of adjacent photoreceptor cells; 2) sensory synapses endowed with synaptic ribbons, formed by basal processes of photoreceptor cells and dendrites of pineal neurons; 3) conventional synapses between pineal neurons, containing both clear and dense-core vesicles at the presynaptic site. Based on these findings, the following interpretations are given: (i) The gap junctions may be involved in an enhancement of electric communication and signal encoding between pineal photoreceptor cells. (ii) The sensory synapses transmit photic signals from the photoreceptor cells to pineal nerve cells. (iii) The conventional synapses are assumed to be involved in a lateral interaction and/or summation of information in the sensory pineal organ. A concept of synaptic relationships among the sensory and neuronal elements in the pineal organ of the ayu is presented.Fellow of the Alexander von Humboldt Foundation, Federal Republic of Germany     

Increased leptin may be involved in the short life span of ayu (Plecoglossus altivelis)

It is well known that ayu (Plecoglossus altivelis) die after spawning and have a life span of only 1 year. The determinants for such a short life span are probably connected with spawning and related changes in hormonal homeostases. One of these changes is that the ayu's feeding activity decreases both during and after spawning. We investigated the relationships among leptin, one of the regulators of food intake, and two other major hormones, 17 beta-estradiol and prolactin (PRL). Ir-leptin levels were significantly higher during spawning, and were associated with a decrease in appetite. Ir-leptin levels were also synchronized with levels of 17 beta-estradiol and PRL-like protein. Therefore, one possible explanation for the decrease in appetite during ayu spawning is that the elevation of 17 beta-estradiol homeostasis induced the secretion of Ir-leptin. The inability to decrease leptin to the basal levels because of high estrogen after spawning could be in part responsible for the short life span of ayu.     

Administration of Chromium(III) and Manganese(II) as a Potential Protective Approach Against Daunorubicin-Induced Cardiotoxicity: in vitro and in vivo Experimental Evidence

Daunorubicin (DNR) is a widely used antitumor drug, but its application is limited because of its cardiotoxic side effects. The present study was designed to investigate the interaction between DNR and cardiac myosin (CM) in the presence of chromium(III) (Cr³⁺) and manganese(II) (Mn²⁺) using fluorescence spectrometry under simulative physiological conditions with the aim of exploring the influence of metal ion on DNR-CM complex and finding out an aggressive approach to abrogate of DNR-induced cardiotoxicity. In detail, the quenching and binding constant of ternary system, including metal ion, DNR, and CM, were measured and compared with the DNR-CM. The data from in vitro experiments indicate that the presence of Cr³⁺ or Mn²⁺ distinctly decreased the binding force between DNR and CM, and alleviated the cardiac toxicity caused by DNR. In addition, the variations in mice body weight and myocardial enzyme level were examined by in vivo experiments. Animals receiving Cr³⁺ or Mn²⁺ supplementation of DNR showed preservation of the normal pattern of the heart, especially 2.0 mg Cr³⁺/kg body wt or 50.0 mg Mn²⁺/kg body wt exhibited an obviously protective effect accompanied with body weight raise when compared with the mice treated with DNR alone, decreased the ratio of heart to body weight (BW) and the ratio of left ventricular mass to BW to the normal levels, and inhibited the leak of myocardial enzyme caused by DNR. As a result, this study suggests that pretreatment of lower dose of Cr³⁺ (2 mg/kg wt) and moderate dose of Mn²⁺ (50 mg/kg wt) might be useful and play an important role in ameliorating the cardiotoxicity of DNR treatment in cancer patients.