Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Attractiveness and aggressiveness: implementing social network analysis in physical education classes

The objective of this study was to detect combinations of interpersonal attractiveness, social power and verbal aggressiveness during physical education and to point out their determinants. A sample of five students’ networks (secondary education) was collected (117 nodes, 64 = boys 53 = girls) using standardized questionnaires. The questionnaires consisted of the network part (relationships of attractiveness, aggressiveness, power developed among students: each student replied about the particular relationship developed with each and every student in their network) and the non-network part (non-network determinants such as age, weight, gender, place of birth, living, family financial status etc.). Social Network Analysis, Spearman test and PCA were implemented. Results: All forms of interpersonal attractiveness are interrelated and correlated to social power. Verbal aggressiveness is negatively related to attractiveness and power. Scientific/task attractiveness may protect from becoming a target of verbal aggressiveness. Good general grade at school and aiming at distinction are the main determinants of emerging attractiveness and power and deterrents of verbal aggressiveness. Females seem scientifically attractive and chosen as mentors more often than males. The types of targets and actors of attractiveness, power, argumentativeness and verbal aggressiveness are proposed. The targets are: “the interpersonally attractive mentor” who is physically, socially and task/scientifically attractive, argumentative and protected from verbal aggressiveness and “the physically attractive target” who is only physically attractive and is verbally targeted. The types of actors are: “the socialized troublemaker” who may be verbally aggressive at times but tends to be attracted and mentored by others and “the lonely coercer” who is marginalized, using verbal aggressiveness and tends not to be mentored and attracted by others. © JPES

Mixed Methods in Analysis of Aggressiveness and Attractiveness: Understanding PE Class Social Networks with Content Analysis

The aim of this study is to detect and analyze the relationship between verbal aggressiveness and interpersonal attractiveness using four secondary-school PE classes in central Greece (88 nodes). Content analysis of open-ended questions, social network analysis, Spearman test and PCA have been implemented. Main results: scientific and social attractiveness are interrelated with a subsequent emergence of power structures and negatively related to verbal aggressiveness. Targets of verbal aggressiveness receive aggressiveness consisting of hurt, irony, rudeness and threat. The general grade and students’ tendency for distinction are positively related to attractiveness and negatively related to verbal aggressiveness. Types of targets of interpersonal attractiveness are proposed (“the untargeted powerful” and “the targeted powerful”). © 2022 by the authors. Licensee MDPI, Basel, Switzerland

The Attractive, the Aggressive and the Withdrawn Student in the University: Social Network and Content Analysis [El Atractivo, el Agresivo y el Estudiante Retraído en la Universidad: Análisis de Redes Sociales y Análisis de Contenido]

The aim of this study is to detect and analyse relationships of attractiveness, social power and aggressiveness in the PE university community. A sample of 197 PE university students from University of Thessaly, Greece participated in the social network study, answering about the relationships developed with their fellow students and providing demographic non-network data as well. After the extraction of results, 8 of them were interviewed to further clarify the motives and thoughts that underlie their behaviour regarding attractiveness, social power and aggressiveness. Social network analysis, carried out with Visone 1.1, statistical analysis, carried out with SPSS 26 and content analysis of the qualitative data – interviews, carried out with MaxQDA 2020 led us to the following conclusions: Scientific attractiveness is related to social power and vice versa, protecting from verbal aggressiveness. Aggressiveness is negatively related to attractiveness and social power. Argumentativeness is important for the position one holds in their network and argumentational deficiency may lead to marginalization. Gender, body characteristics and academic distinction affect attractiveness and aggressiveness emergence. © 2022, Hipatia Editorial. All rights reserved

The powerful, the powerless, and the empowered: Visualizations of power in high school and university through social network analysis

The investigation uses Popitz’s power theory (1992) to examine relationships among social power position, attractiveness, and verbal aggressiveness comparing social networks of high school and university students. 117 high school PE students and 195 university PE students participated in the research completing both a network and a joint non-network questionnaire. Visone 1.1 software was used for the processing of the network data and SPSS 26 was implemented for the non-network data. The results revealed in both settings that students demonstrating scientific/task attractiveness develop authoritative power/power of internalized control in their network and are protected from verbal aggressiveness and enforcement of instrumental power/power of externalized control. Social attractiveness enhances the development of authoritative power/power of internalized control in high school only. In this research, a type of powerful student is suggested who does not tend to concentrate power but rather to share power for empowering the powerless ones. © The Author(s) 2022

Unveiling negative behaviors in the academic arena

There is increasing evidence that the appearance of negative behaviors is omnipresent not only at the secondary but also at the academic institutions. The aim of the present study is the investigation of inclinations in terms of practicing and being a target of three negative behavioral phenomena; verbal aggressiveness, bullying and Machiavellianism among university students. A sample of 17 classes of totally 783 undergraduate students (405 females and 378 males) from Physical Education and Sports Science, Veterinary and Business Administration academic departments in Greece was scrutinized with social network analysis as far as the afore mentioned three destructive behaviors as structural phenomena were concerned. Standardized questionnaires composed of non-network and network parts were distributed. Visone software was implemented for calculating network variables (network analysis algorithms were used: In/outdegree, Katz status, PageRank, authority). Social Network Analysis and Spearman test (SPSS) have been applied in order to reveal any reliance among departments, behaviors and general characteristics in question. According to the basic results of the present study, there is a noticeable variation among the three academic fields concerning their value system. Physical Education department seems to be characterized by a spirit of competitiveness and great discipline fulfilling athletic achievements. Veterinary department appears to be depicted by scientific and selflessness standards while Business Administration department seems to be devoted to its sole aim regarding the dominance of the market. To combat these negative behaviors, it is necessary to detect their specific determinants in order to formulate effective tactics for nipping such behaviors in the bud at the educational settings. © 2020 Common Ground Research Networks. All rights reserved

Social network analysis in physical education classes: Attractiveness of individuals and targets of verbal aggressiveness

The objective of this study is to detect combinations of students’ interpersonal attractiveness and verbal aggressiveness during physical education and to point out their determinants. A sample of four students’ networks (88 nodes—50 male and 38 female) from secondary education in Trikala, Greece has been collected. Standardized questionnaires were used. Social network analysis, Spearman and PCA have been implemented. Main results: Scientific attractiveness is positively related to social and physical attractiveness. It seems to protect from being a target of verbal aggressiveness. Social attractiveness seems to protect less than scientific attractiveness from being a target for verbal aggressiveness, while physical attractiveness encourages receiving verbal aggressiveness. Specific behavioral types are proposed: “the powerful and attractive mentor” who consists of scientific, social and physical attractiveness, is recognized as a mentor, attracts others’ sympathy and at the same time they are protected from all forms of verbal aggressiveness and “the socially unattractive target” who is physically attractive and at the same time a target for all forms of verbal aggressiveness. © Common Ground Research Networks, Maria Litsa, Alexandra Bekiari, Kyriaki Spanou, All Rights Reserved

GnRH Stimulates Expression of PACAP in the Pituitary Gonadotropes via Both the PKA and PKC Signaling Systems

Abstract Recent studies have demonstrated a clear role for pituitary adenylate cyclase-activating polypeptide (PACAP) in the regulation of gonadotropin biosynthesis and secretion, both alone and in conjunction with GnRH. First defined as a hypothalamic releasing factor, PACAP subsequently has been identified in the gonadotrope subpopulation of the anterior pituitary gland, suggesting that PACAP may act as an autocrine-paracrine factor in this tissue. In initial studies, we determined that GnRH markedly stimulated endogenous PACAP mRNA levels and promoter-reporter activity in the mature gonadotrope cell line, LβT2. GnRH-stimulated rat PACAP promoter activity was blunted with deletion from position −915 to −402 and eliminated with further truncation to position −77 relative to the transcriptional start site. Site-directed mutagenesis demonstrated a functional requirement for a cAMP response element (CRE)-like site at position −205 and an activating protein-1 (AP-1)-like site at position −275, both of which bound CRE binding protein and AP-1 family members on EMSA. Treatment with pharmacological activators or inhibitors of second messenger signaling pathways implicated the protein kinase A, protein kinase C, and MAPK pathways in the GnRH response. In support of these in vitro data, we demonstrate that JunB binds to the rat PACAP gene promoter by chromatin immunoprecipitation assay and that small interfering RNA knockdown of JunB, cFos, and CRE binding protein factors blunts PACAP expression. In summary, these results further elucidate the complex functional interactions between PACAP and GnRH in the anterior pituitary. Specifically, these studies demonstrate that GnRH-stimulated PACAP gene expression is mediated via multiple signaling pathways acting on CRE/AP-1 sites in the proximal gene promoter. Because both PACAP and GnRH regulate gonadotropin biosynthesis and secretion, these results provide important insight into the critical fine tuning of gonadotrope function and, thereby, the maintenance of normal reproductive function