CELLULAR AND MOLECULAR MECHANISMS OF BIOMINERALISATION IN A SILICIFYING HAPTOPHYTE PRYMNESIUM NEOLEPIS

Full version unavailable due to 3rd party copyright restrictions.Haptophytes are renowned for the most prominent and biogeochemically important group of marine calcifiers: coccolithophores. The unexpected discovery of a unique, silicifying member of this clade - Prymnesium neolepis - prompted questions regarding mechanisms of silicification and their origin in the calcifier-dominated haptophytes. To address these questions I used cell physiology, biochemistry and molecular approaches, investigating cellular and molecular mechanisms involved in silicification in haptophytes. Comparisons of this system with calcification in coccolithophores and other silica-based systems in eukaryotes were also made. Here I report that P. neolepis is an obligate silicifier, producing silica scales in a process fundamentally different to that observed in coccolithophores. Scale deposition and secretion in P. neolepis is localized in the posterior, vacuolar part of the cell rather than in the anterior part near the flagellar roots as in calcifying coccolithophores. The organic matrix underlying silica scales in P. neolepis was found to be non-homologous with organic scales, which in coccolithophores serve as coccolith baseplates. This suggests, that silica scales and coccoliths arise from two distinct, most likely non-homologous processes, which is further supported by the comparative investigation of the role of cytoskeleton in silica scale production in P. neolepis and coccolithogenesis in a representative calcifier, Coccolithus pelagicus. Using cytoskeleton inhibitors I established, that the cytoskeleton components used for morphogenesis and secretion of biomineralised structures are different in these two systems. Analysis of P. neolepis biosilica revealed the presence of an intimately associated organic fraction consisting of a putatively chitin-containing material, potentially serving as an organic matrix underlying silica scales. Further biochemical investigation of the biosilica-associated organics confirmed the presence of long chain polyamines (LCPAs) dissimilar to those previously reported in diatoms and sponges. Additionally, a potentially novel, proline and lysine-rich protein sharing a weak homology with lipocalins was recovered, suggesting that this silicification system is unique to haptophytes. Several theories concerning acquisition of the ability to silicify in haptophytes were proposed. Overall, the findings presented in this study provide a detailed description of Si biomineralisation system in this unique, silicifying haptophyte and supply novel information on biomineralisation systems in marine haptophytes. This study contributes a basis on which the phenomenon of silicification in haptophytes can be further investigated, as well as novel information which can be further used in elucidation of origins of silicification in algae and other Eucarya.EU Interreg IV Marinexus Projec

Apprehensions of Unauthorized Migrants Along the Southwest Border: Fact Sheet

[Excerpt] According to the U.S. Border Patrol (USBP), the number of illegal alien apprehensions between southern ports of entry (POE) in the United States has generally declined from about 1.6 million in FY2000 to nearly 420,000 in FY2013. Much of this downward trend has occurred since FY2005. Apprehensions of unauthorized migrants by the USBP along the U.S.-Mexico border fell from about 1.2 million in FY2005 to a 41-year low of 328,000 in FY2011, before climbing to 357,000 in FY2012 and 414,397 in FY2013

Gençlerde Sosyal Kaygı ve Depresyonun Problemli İnternet Kullanımıyla İlgili Bilişlerle İlişkisi

Presence of psychopathology (e.g., depression and anxiety) has found to be related to an increased vulnerability to develop problematic Internet use (PIU). The current study aimed to investigate the effects of social anxiety and depression on cognitions related to PIU based on a cognitive behavioral framework in youths. The Online Cognition Scale (OCS), The Beck Depression Inventory (BDI), The Liebowitz Social Anxiety Scale (LSAS) and Demographic Information Form were administered and hierarchical multiple regression analyses were used to ascertain these effects as well as to determine the roles of socio-demographic variables (age, gender, type of residence, and monthly income), romantic relationship status, and time spent online, using a sample of 448 Turkish university students aged 18 to 25 years. The results revealed significant effects of gender (being male) and time spent online on cognitions about PIU. However, the effects of romantic relationship status were found to be insignificant. Fear/ anxiety and depression were positively correlated with cognitions about PIU. Avoidance was not found to be correlated with cognitions about PIU. Examining the roles of social anxiety and depressi Psikopatolojinin varlığının (örneğin depresyon ve kaygı), sorunlu İnternet kullanımına yatkınlığı arttırdığı ortaya konmuştur. Bu çalışmanın amacı, bilişsel davranışçı yaklaşım çerçevesinde sosyal kaygının ve depresyonun sorunlu İnternet kullanımı ile ilgili bilişler üzerindeki etkisini gençler üzerinde araştırmaktır. Çalışmaya, 18-25 yaş aralığındaki 448 üniversite öğrencisi katılmıştır. Sosyal kaygının ve depresyonun etkisinin yanı sıra sosyodemografik değişkenlerin (yaş, cinsiyet, ikamet türü ve aylık gelir), romantik bir ilişkiye sahip olmanın ve Internet başında geçirilen zamanın sorunlu İnternet kullanımı ile ilgili bilişler üzerindeki etkisini araştırmak amacıyla çoklu hiyerarşik regresyon analizleri gerçekleştirilmiştir. Elde edilen bulgular, cinsiyetin (erkek olmanın) ve İnternet başında geçirilen zamanın sorunlu Internet kullanımı ile ilgili bilişler üzerindeki etkisinin anlamlı olduğunu göstermiştir. Bununla birlikte romantik bir ilişkiye sahip olmanın sorunlu İnternet kullanımı ile ilgili bilişler üzerindeki etkisi anlamsızdır. Korku-kaygı ve depresyon, sorunlu İnternet kullanımı ile ilgili bilişler ile pozitif korelasyon göstermiştir. Bununla birlikte kaçınmanın sorunlu İnternet kullanımı ile ilgili bilişler üzerindeki etkisi anlamsızdır. Sosyal kaygının ve depresyonun sorunlu İnternet kullanımı ile ilgili bilişler üzerindeki rollerinin araştırılmış olması, ileride bu alanda yapılacak araştırmalara katkı sağlayacaktır

Evolution of a polymodal sensory response network

Background: Avoidance of noxious stimuli is essential for the survival of an animal in its natural habitat. Some avoidance responses require polymodal sensory neurons, which sense a range of diverse stimuli, whereas other stimuli require a unimodal sensory neuron, which senses a single stimulus. Polymodality might have evolved to help animals quickly detect and respond to diverse noxious stimuli. Nematodes inhabit diverse habitats and most nematode nervous systems are composed of a small number of neurons, despite a wide assortment in nematode sizes. Given this observation, we speculated that cellular contribution to stereotyped avoidance behaviors would also be conserved between nematode species. The ASH neuron mediates avoidance of three classes of noxious stimuli in Caenorhabditis elegans. Two species of parasitic nematodes also utilize the ASH neuron to avoid certain stimuli. We wanted to extend our knowledge of avoidance behaviors by comparing multiple stimuli in a set of free-living nematode species. Results: We used comparative behavioral analysis and laser microsurgery to examine three avoidance behaviors in six diverse species of free-living nematodes. We found that all species tested exhibit avoidance of chemo-, mechano- and osmosensory stimuli. In C. elegans, the bilaterally symmetric polymodal ASH neurons detect all three classes of repellant. We identified the putative ASH neurons in different nematode species by their anatomical positions and showed that in all six species ablation of the ASH neurons resulted in an inability to avoid noxious stimuli. However, in the nematode Pristionchus pacificus, the ADL neuron in addition to the ASH neuron contributed to osmosensation. In the species Caenorhabditis sp. 3, only the ASH neuron was required to mediate nose touch avoidance instead of three neurons in C. elegans. These data suggest that different species can increase or decrease the contribution of additional, non-ASH sensory neurons mediating osmosensation and mechanosensation. Conclusion: The overall conservation of ASH mediated polymodal nociception suggests that it is an ancestral evolutionarily stable feature of sensation. However, the finding that contribution from non-ASH sensory neurons mediates polymodal nociception in some nematode species suggests that even in conserved sensory behaviors, the cellular response network is dynamic over evolutionary time, perhaps shaped by adaptation of each species to its environment

Psychological distress and anxiety among housewives: the mediational role of perceived stress, loneliness, and housewife burnout

Housewives are experiencing chronic stress when dealing with multiple roles (cooking, shopping, tidying the house) in their daily life. Although earlier studies have documented a significant link between role overload and stress-psychological well-being in the workplace, few studies have been conducted among housewives despite their high anxiety and burnout reports. The diathesis-stress model and transactional model of stress indicate that there may be somecontributory factors related to mental health. Within these frameworks, this research aimed to examine housewives' psychological distress and anxiety by focusing on three contributory factors namely housewife burnout, perceived stress, and loneliness. The present study was a novel contribution to the literature investigating the mediating roles of those three contributory factors between psychological distress and anxiety among housewives. Participants were 500 volunteer housewives between the ages of 20 and 70 from Turkey. In addition to Demographic Information Form, The Perceived Stress Scales (PSS-10), The General Health Questionnaire (GHQ-12), The UCLA Loneliness Scale-Version 3 (UCLA LS3), The Housewives Burnout Questionnaire (CUBAC), and The Beck Anxiety Inventory (BAI) were used. Results showed that there were four paths between psychological distress and anxiety in the model, explaining 31.19% of the total variance in anxiety in housewives. The relationship between psychological distress and anxiety was mediated by perceived distress, loneliness, and housewife burnout. Specifically, the higher psychological distress and higher anxiety relationship were associated with higher perceived distress, higher loneliness, and higher housewife burnout. The findings provide beneficial insight for clinicians to prioritize the abandonment of the cope with loneliness, perceived stress, and burnout while working with housewives having psychological distress and anxiety.Publisher's Versio

A Scalable Null Model for Directed Graphs Matching All Degree Distributions: In, Out, and Reciprocal

Degree distributions are arguably the most important property of real world networks. The classic edge configuration model or Chung-Lu model can generate an undirected graph with any desired degree distribution. This serves as a good null model to compare algorithms or perform experimental studies. Furthermore, there are scalable algorithms that implement these models and they are invaluable in the study of graphs. However, networks in the real-world are often directed, and have a significant proportion of reciprocal edges. A stronger relation exists between two nodes when they each point to one another (reciprocal edge) as compared to when only one points to the other (one-way edge). Despite their importance, reciprocal edges have been disregarded by most directed graph models. We propose a null model for directed graphs inspired by the Chung-Lu model that matches the in-, out-, and reciprocal-degree distributions of the real graphs. Our algorithm is scalable and requires $O(m)$ random numbers to generate a graph with $m$ edges. We perform a series of experiments on real datasets and compare with existing graph models.Comment: Camera ready version for IEEE Workshop on Network Science; fixed some typos in tabl