The beginnings

The simple title tells many things. Of course, it could tell almost nothing since a well-known motto says that ‘everything must have a beginning’. However, another motto is more appropriate here: ‘A journey of a thousand miles must begin with a single step’. Yes, we remember here the first steps of a journey of more than 60/2 years; steps that set the basis for the first group of people working on Graph Theory not only at Barcelona, but in the whole of Spain. And all this began when Miguel Angel FiolPeer Reviewe

Contribution of marine zooplankton time series to the United Nations Decade of Ocean Science for Sustainable Development

Zooplankton play a central role in marine trophic webs, influencing both biogeochemistry and productivity of the oceans. Changes in their communities are important indicators of overall ecosystem health and global change impacts. With increasing exploitation and pressures on the marine environment, there is a growing need for high-resolution monitoring of marine zooplankton to provide detailed information about seasonal to decadal changes at local, regional, and global scales. This crucial knowledge is gathered mainly through long-term time series, which are key to characterizing and forecasting changes in marine zooplankton assemblages. In this Introduction, and through the articles included in this Themed Article Set, we bring together new insights, issuing from data time series, into zooplankton population dynamics.We also take up the application of such time series to the understanding of global change impacts on marine ecosystems and in providing advice on sustainable management of marine ecosystem resources and services. We highlight the importance of maintaining and supporting long-term marine zooplankton time series as key contributors to the development and advancement of the United Nations’ Decade of Ocean Science for Sustainable Development Goal 13-Climate action and Goal 14-Life below water.Versión del editor2,27

Correlation between ion hopping conductivity and near constant loss in ionic conductors

For ionic conductivity relaxation in ionically conducting materials we predict in the framework of the coupling model that the magnitude of the ubiquitous near constant loss correlates with the activation energy E_(a) for independent ion hopping. Using experimental data of a variety of ionic conductors, this correlation has been borne out. The model also explains the observed correlation between the magnitude of the near constant loss and the value of the dc conductivity at room temperature, as well as the temperature dependence for the near constant loss

Individual growth rate (IGR) and aminoacyl-tRNA synthetases (AARS) activity as individual-based indicators of growth rate of North Pacific krill, Euphausia pacifica

We investigated aminoacyl-tRNA synthetases (AARS) activity and individual growth rate (IGR) as individual-based in situ indicators of growth in adult krill, Euphausia pacifica. AARS enzymes catalyze the first step in protein synthesis while the IGR method is based on changes in body length during molting. Growth rates of field-collected krill were measured via the IGR method and individuals were subsequently preserved for AARS analysis to yield paired measurements. Our results show that conditions during the IGR incubation period influenced AARS activity in these individuals precluding a direct comparison but revealing the different timescales across which these two measures integrate. Importantly, they show that AARS activity provides a snap-shot image of an organism's metabolism, while IGR of krill is thought to integrate their environmental experience over several days. Each method would require repeated measurements to estimate population growth rates integrated over seasonal or generational time scales. As part of this project, we investigated how specific the AARS assay is to protein synthesis by testing a modified protocol that includes an additional blank and found evidence that the current assay may be measuring other cellular processes in addition to its intended signal. Our results suggest that a new NADH Blank might be optimized to improve the specificity of the assay.Postprint2,26

Are we missing a mesopelagic-demersal coupling?

Despite demersal trawling monitoring programs are not aimed at quantifying mesopelagic organisms, they are recurrently captured as by catch between 30 and 800 m depth. These species are mostly diel vertical migrants, with differentiated behavior from benthic and demersal ones. Nevertheless, they are sometimes captured in large quantities (both abundance and biomass) although absent on other occasions. The co-occurrence observed with demersal populations may probably be due to the daytime and location of samplings, i.e. depth and type of bottom (habitat). In order to understand the mesopelagic-demersal coupling, we discuss spatio-temporal patterns observed along the Spanish Mediterranean coast during the 1994-2012 MEDITS survey.FEM

Loss of the PTCH1 tumor suppressor defines a new subset of plexiform fibromyxoma.

BackgroundPlexiform fibromyxoma (PF) is a rare gastric tumor often confused with gastrointestinal stromal tumor. These so-called "benign" tumors often present with upper GI bleeding and gastric outlet obstruction. It was recently demonstrated that approximately one-third of PF have activation of the GLI1 oncogene, a transcription factor in the hedgehog (Hh) pathway, via a MALAT1-GLI1 fusion protein or GLI1 up-regulation. Despite this discovery, the biology of most PFs remains unknown.MethodsNext generation sequencing (NGS) was performed on formalin-fixed paraffin-embedded (FFPE) samples of PF specimens collected from three institutions (UCSD, NCI and OHSU). Fresh frozen tissue from one tumor was utilized for in vitro assays, including quantitative RT-PCR and cell viability assays following drug treatment.ResultsEight patients with PF were identified and 5 patients' tumors were analyzed by NGS. An index case had a mono-allelic PTCH1 deletion of exons 15-24 and a second case, identified in a validation cohort, also had a PTCH1 gene loss associated with a suspected long-range chromosome 9 deletion. Building on the role of Hh signaling in PF, PTCH1, a tumor suppressor protein, functions upstream of GLI1. Loss of PTCH1 induces GLI1 activation and downstream gene transcription. Utilizing fresh tissue from the index PF case, RT-qPCR analysis demonstrated expression of Hh pathway components, SMO and GLI1, as well as GLI1 transcriptional targets, CCND1 and HHIP. In turn, short-term in vitro treatment with a Hh pathway inhibitor, sonidegib, resulted in dose-dependent cell killing.ConclusionsFor the first time, we report a novel association between PTCH1 inactivation and the development of plexiform fibromyxoma. Hh pathway inhibition with SMO antagonists may represent a target to study for treating a subset of plexiform fibromyxomas

Horizontal distribution of deep sea microplankton: A new point of view for marine biogeography.

An investigation on microplankton composition and spatial distribution has been carried out around Italian seas. The analysis of 53 samples, collected in 2017 at two depths in 27 different stations, has led to a scenario of horizontal distribution of microplankton. Dinophyta and Ciliophora were chosen as representatives of the whole microplankton community. A total of 60 genera were identified. Cluster analysis of data regarding taxa presence and abundance led us to recognize that similarities between surface stations were more evident than those between deep ones. Furthermore, we conducted an inter-annual comparison with available data from the South Adriatic Sea (2013, 2015). The higher dissimilarity between deep sea samples was also confirmed in a relatively smaller geographic area. The dissimilarity of deep-sea samples does not correspond to a higher habitat diversification, in terms of abiotic parameters. It has been suggested that the negligible biological connectivity in the deep, for those micro-organisms not able to perform wide spatial migrations, could produce such a biological diversificatio

Higher accuracy approximate solution for oscillations of a mass attached to a stretched elastic wire by rational harmonic balance method

A second-order modified rational harmonic balance method is used for approximately solve the nonlinear differential equation that governs the oscillations of a system typified as a mass attached to a stretched elastic wire for which the restoring force for this oscillator has an irrational term with a parameter lambda that characterizes the system. A frequency-amplitude relation is constructed and this frequency is valid for the complete range of oscillation amplitudes A and parameter lambda, and excellent agreement of the approximate frequencies with the exact one is demonstrated and discussed. The discrepancy between the approximate frequency and the exact one never exceed 0.12%. This error corresponds to lambda = 1. while for lambda < 1 the relative error is much lower. For example, its value is lower than 0.017% for lambda = 0.5

Ontogenetic Responses of Calanus chilensis to Hypoxia from Northern Chile (23ºS), Humboldt Current Ecosystem

Eastern Boundary Upwelling Systems are being subjected to expansion, intensification and shoaling of Oxygen Minimum Zones (OMZ's), as a result of ongoing climate change. To understand how dominant epipelagic copepods may respond to stressful conditions induced by low oxygen, we experimentally studied the effect of hypoxia over the stage-specific physiology of Calanus chilensis from the Mejillones Bay (23°S — 70°W), northern Chile, during the winters of 2013 and 2014. Females, eggs and nauplii (NI to NIV) of C. chilensis were incubated under hypoxia (~0.7 mg O2 L-1) and normoxia (~8.3 mg O2 L-1) conditions at a constant temperature of 14ºC as to estimate egg production rate (EPR), hatching success (HS) and naupliar growth and development time. Additionally, we estimated survivorship by using Neutral Red technique, and also examined female metabolism by measuring specific activity of the enzymes Aminoacyl-tRNA synthetases (spAARS) (growth index) and the electron transport system (spETS) (potential respiration). Survival of females and EPR were not significantly affected by dissolved oxygen (DO) conditions, coinciding with no significant changes in their metabolism. By contrast, HS was reduced from normoxia (70%) to hypoxia (30%), whereas naupliar growth (NI to NIII) was lower under hypoxia (0.155 ± 0.007 d-1) than normoxia (0.237 ± 0.006 d-1), resulting also in a longer development time, 6.490 ± 0.353 d and 4.238 ± 0.149 d, respectively. Most eggs and nauplii collected at the end of the experiments were alive, although a higher proportion of organisms were recovered in normoxia than hypoxia. Our results revealed stage-specific responses to hypoxia in C. chilensis and the importance of ontogenetic responses to variable levels of oxygenation in the upwelling zone