Environmental controls on pteropod biogeography along the Western Antarctic Peninsula

Pteropods are abundant zooplankton in the Western Antarctic Peninsula (WAP) and important grazers of phytoplankton and prey for higher trophic levels. We analyzed long-term (1993-2017) trends in summer (January-February) abundance of WAP pteropods in relation to environmental controls (sea ice, sea surface temperature, climate indices, phytoplankton biomass and productivity, and carbonate chemistry) and interspecies dynamics using general linear models. There was no overall directional trend in abundance of thecosomes, Limacina helicina antarctica and Clio pyramidata, throughout the entire WAP, although L. antarctica abundance increased in the slope region and C. pyramidata abundance increased in the South. High L. antarctica abundance was strongly tied to a negative Multivariate El Nino Southern Oscillation Index the previous year. C. pyramidata abundance was best explained by early sea ice retreat 1-yr prior. Abundance of the gymnosome species, Clione antarctica and Spongiobranchaea australis, increased over the time series, particularly in the slope region. Gymnosome abundance was positively influenced by abundance of their prey, L. antarctica, during the same season, and late sea ice advance 2-yr prior. These trends indicate a shorter ice season promotes longer periods of open water in spring/summer favoring all pteropod species. Weak relationships were found between pteropod abundance and carbonate chemistry, and no long-term trend in carbonate parameters was detected. These factors indicate ocean acidification is not presently influencing WAP pteropod abundance. Pteropods are responsive to the considerable environmental variability on both temporal and spatial scales-key for predicting future effects of climate change on regional carbon cycling and plankton trophic interactions

Genome-based discovery of polyketide-derived secondary metabolism pathways in the barley pathogen <i>Ramularia collo-cygni</i>

Ramularia collo-cygni causes Ramularia leaf spot (RLS) disease of barley. The fungus develops asymptomatically within its host until late in the growing season, when necrotic lesions become visible on upper leaves. Fungal secondary metabolites (SM) have been proposed as important factors in RLS lesion formation but the biosynthetic pathways involved remain largely unknown. Mining the R. collo-cygni genome revealed the presence of 10 polyketide synthases (PKS), 10 nonribosomal peptide synthetases (NRPS), and 3 hybrid PKS-NRPS (HPS) identified within clusters of genes with predicted functions associated with secondary metabolism. SM core genes along with their predicted transcriptional regulators exhibited transcriptional coexpression during infection of barley plants. Moreover, their expression peaked during early stages of host colonization and preceded or overlapped with the appearance of disease symptoms, suggesting that SM may manipulate the host to promote colonization or protect R. collo-cygni from competing organisms. Accordingly, R. collo-cygni inhibited the growth of several fungi in vitro, indicating that it synthesized and excreted antifungal agents. Taken together, these findings demonstrate that the R. collo-cygni genome contains the genetic architecture to synthesize a wide range of SM and suggests that coexpression of PKS and HPS is associated with competitive colonization of the host and early symptom development. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY 4.0 International license . </jats:p

Exploring the Levinthal limit in protein folding

According to the thermodynamic hypothesis, the native state of proteins is uniquely defined by their amino acid sequence. On the other hand, according to Levinthal, the native state is just a local minimum of the free energy and a given amino acid sequence, in the same thermodynamic conditions, can assume many, very different structures that are as thermodynamically stable as the native state. This is the Levinthal limit explored in this work. Using computer simulations, we compare the interactions that stabilize the native state of four different proteins with those that stabilize three non-native states of each protein and find that the nature of the interactions is very similar for all such 16 conformers. Furthermore, an enhancement of the degree of fluctuation of the non-native conformers can be explained by an insufficient relaxation to their local free energy minimum. These results favor Levinthal's hypothesis that protein folding is a kinetic non-equilibrium process.FCT - Foundation for Science and Technology, Portugal [UID/Multi/04326/2013]; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Conselho Nacional de Desenvolvimento Cientia co e Tecnologico (CNPq

Virtual environment for studying the docking interactions of rigid biomolecules with haptics

Haptic technology facilitates user interaction with the virtual world via the sense of touch. In molecular docking, haptics enables the user to sense the interaction forces during the docking process. Here we describe a haptics-assisted interactive software tool, called Haptimol RD, for the study of docking interactions. By utilising GPU-accelerated proximity querying methods very large systems can now be studied. Methods for force scaling, multipoint collision response and haptic navigation are described that address force stability issues that are particular to the interactive docking of large systems. Thus Haptimol RD expands, for the first time, the use of interactive biomolecular haptics to the study of protein-protein interactions. Unlike existing approaches, Haptimol RD is designed to run on relatively inexpensive consumer-level hardware and is freely available to the community

Within-person variation in serum thyrotropin concentration: main sources, potential underlying biological mechanisms, and clinical implications

Background: Individuals exhibit fluctuations in the concentration of serum thyroid-stimulating hormone (TSH) over time. The scale of these variations ranges from minutes to hours, and from months to years. The main factors contributing to the observed within-person fluctuations in serum TSH comprise pulsatile secretion, circadian rhythm, seasonality, and ageing. In clinical practice and clinical research however, such within-person biological variation in serum TSH concentrations is often not considered. The aim of this review is to present an overview of the main sources of within-person variation in TSH levels, as well as the potential underlying biological mechanisms, and the clinical implications.Summary: In euthyroid individuals, the circadian rhythm, with a nocturnal surge around 02:00-04:00 h and a nadir during daytime has the greatest impact on variations in serum TSH concentrations. Another source of within-person variation in TSH levels is seasonality, with generally higher levels during the cold winter months. Since TSH is secreted in a pulsatile manner, TSH levels also fluctuate over minutes. Furthermore, elevated TSH levels have been observed with ageing. Other factors that affect TSH levels include thyroid peroxidase (TPO)-antibody positivity, BMI, obesity, smoking, critical illness, and many xenobiotics, including environmental pollutants and drugs. Potential underlying biological mechanisms of within-person variation in TSH levels can be safely concluded from the ability of TSH to respond quickly to changes in cues from the internal or external environment in order to maintain homeostasis. Such cues include the biological clock, environmental temperature, and length of day. The observed increase in TSH level with ageing can be explained at a population level and at an organism level. In clinical practice, the season for thyroid testing can influence a patient's test result and it occurs frequently that subclinical hypothyroid patients normalize to euthyroid levels over time without intervention.Conclusions: Serum TSH concentrations vary over time within an individual, which is caused by multiple different internal and external factors. It is important to take the within-person variations in serum TSH concentrations into account when testing a patient in clinical practice, but also in performing clinical research.Diabetes mellitus: pathophysiological changes and therap

Relationships between 24-hour LH and testosterone concentrations and with other pituitary hormones in healthy older men

Objective: To investigate the relationship between LH and testosterone (T), which characteristics associate with the strength of this relationship, and their interrelationships with GH, TSH, cortisol, and ACTH.Design: Hormones were measured in serum samples collected every 10 minutes during 24 hours from 20 healthy men, comprising 10 offspring of long-lived families and 10 control subjects, with a mean (SD) age of 65.6 (5.3) years. We performed cross-correlation analyses to assess the relative strength between 2 timeseries for all possible time shifts.Results: Mean (95% CI) maximal correlation was 0.21 (0.10-0.31) at lag time of 60 minutes between LH and total T concentrations. Results were comparable for calculated free, bioavailable, or secretion rates of T. Men with strong LH-T cross-correlations had, compared with men with no cross-correlation, lower fat mass (18.5 [14.9-19.7] vs. 22.3 [18.4-29.4] kg), waist circumference (93.6 [5.7] vs. 103.1 [12.0] cm), high-sensitivity C-reactive protein (0.7 [0.4-1.3] vs. 1.8 [0.8-12.3] mg/L), IL-6 (0.8 [0.6-1.0] vs. 1.2 [0.9-3.0] pg/mL), and 24-hour mean LH (4.3 [2.0] vs. 6.1 [1.5] U/L), and stronger LH-T feedforward synchrony (1.5 [0.3] vs. 1.9 [0.2]). Furthermore,T was positively cross-correlated withTSH (0.32 [0.21-0.43]), cortisol (0.26 [0.19-0.33]), and ACTH (0.26 [0.19-0.32]).Conclusions: LH is followed by T with a delay of 60 minutes in healthy older men. Men with a strong LH-T relationship had more favorable body composition, inflammatory markers, LH levels, and LH-T feedforward synchrony. We observed positive correlations between T and TSH, cortisol, and ACTH.Pathophysiology, epidemiology and therapy of agein

Diagnosis-related deterioration of lung function after extracorporeal membrane oxygenation.

The aim of the study was to assess lung function longitudinally after neonatal extracorporeal membrane oxygenation (ECMO), and to identify any effects of diagnosis and perinatal characteristics. 121 neonatal ECMO-treated children (70 with meconium aspiration syndrome, 20 congenital diaphragmatic hernia and 31 with other diagnoses) performed a total of 191 lung function measurements at 5, 8 and/or 12 yrs. We assessed dynamic and static lung volumes, reversibility of airway obstruction and diffusion capacity. Mean SDS forced expiratory volume in 1 s (FEV(1)) at 5 yrs before and after bronchodilation (-0.51 and 0.07) was significantly higher than at 8 (-0.79 and -0.4; p<0.04) and 12 yrs (-1.10 and -0.52; p<0.003). Mean SDS for all spirometric parameters before and after bronchodilation were significantly lower in the congenital diaphragmatic hernia group compared with the other diagnostic groups (all p</=0.025). A significant volume of trapped air was observed in 86% patients with congenital diaphragmatic hernia, 50% with meconium aspiration syndrome and 58% with other diagnoses. After bronchodilation, mean SDS FEV(1) and forced vital capacity were negatively influenced by duration of ventilation (both p<0.001) and duration of ECMO (p=0.003 and p=0.02, respectively). Long-term pulmonary sequelae after neonatal ECMO-treatment mainly occur in congenital diaphragmatic hernia patients and tend to deteriorate over time

Growth and development after oesophageal atresia surgery: Need for long-term multidisciplinary follow-up

Abstract Survival rates in oesophageal atresia patients have reached over 90%. In long-term follow-up studies the focus has shifted from purely surgical or gastrointestinal evaluation to a multidisciplinary approach. We reviewed the literature on the long-term morbidity of these patients and discuss mainly issues of physical growth and neurodevelopment. We conclude that growth problems–both stunting and wasting–are frequently seen, but that sufficient longitudinal data are lacking. Therefore, it is unclear whether catch-up growth into adolescence and adulthood occurs. Data on determinants of growth retardation are also lacking in current literature. Studies on neurodevelopment beyond preschool age are scarce but oesophageal atresia patients seem at risk for academic problems and motor function delay. Many factors contribute to the susceptibility to growth and development problems and we propose a multidisciplinary follow-up schedule into adulthood future care which may help improve quality of life