Trade, diplomacy, and warfare: The Quest for elite rhizobia inoculant strains

Rhizobia form symbiotic nitrogen-fixing nodules on leguminous plants, which provides an important source of fixed nitrogen input into the soil ecosystem. The improvement of symbiotic nitrogen fixation is one of the main challenges facing agriculture research. Doing so will reduce the usage of chemical nitrogen fertilizer, contributing to the development of sustainable agriculture practices to deal with the increasing global human population. Sociomicrobiological studies of rhizobia have become a model for the study of the evolution of mutualistic interactions. The exploitation of the wide range of social interactions rhizobia establish among themselves, with the soil and root microbiota, and with the host plant, could constitute a great advantage in the development of a new generation of highly effective rhizobia inoculants. Here, we provide a brief overview of the current knowledge on three main aspects of rhizobia interaction: trade of fixed nitrogen with the plant; diplomacy in terms of communication and possible synergistic effects; and warfare, as antagonism and plant control over symbiosis. Then, we propose new areas of investigation and the selection of strains based on the combination of the genetic determinants for the relevant rhizobia symbiotic behavioral phenotypes

Metabolic modelling reveals the specialization of secondary replicons for niche adaptation in Sinorhizobium meliloti

The genome of about 10% of bacterial species is divided among two or more large chromosome-sized replicons. The contribution of each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model of the legume symbiont Sinorhizobium meliloti that is integrated with carbon utilization data for 1,500 genes with 192 carbon substrates. Growth of S. meliloti is modelled in three ecological niches (bulk soil, rhizosphere and nodule) with a focus on the role of each of its three replicons. We observe clear metabolic differences during growth in the tested ecological niches and an overall reprogramming following niche switching. In silico examination of the inferred fitness of gene deletion mutants suggests that secondary replicons evolved to fulfil a specialized function, particularly host-associated niche adaptation. Thus, genes on secondary replicons might potentially be manipulated to promote or suppress host interactions for biotechnological purposes

Metabolic modelling reveals the specialization of secondary replicons for niche adaptation in Sinorhizobium meliloti

The genome of about 10% of bacterial species is divided among two or more large chromosome-sized replicons. The contribution of each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model of the legume symbiont Sinorhizobium meliloti that is integrated with carbon utilization data for 1,500 genes with 192 carbon substrates. Growth of S. meliloti is modelled in three ecological niches (bulk soil, rhizosphere and nodule) with a focus on the role of each of its three replicons. We observe clear metabolic differences during growth in the tested ecological niches and an overall reprogramming following niche switching. In silico examination of the inferred fitness of gene deletion mutants suggests that secondary replicons evolved to fulfil a specialized function, particularly host-associated niche adaptation. Thus, genes on secondary replicons might potentially be manipulated to promote or suppress host interactions for biotechnological purposes

Are We Preparing the Next Generation of Fisheries Professionals to Succeed in their Careers?: A Survey of AFS Members

Natural resource professionals have frequently criticized universities for poorly preparing graduates to succeed in their jobs. We surveyed members of the American Fisheries Society to determine which job skills and knowledge of academic topics employers, students, and university faculty members deemed most important to early-career success of fisheries professionals. Respondents also rated proficiency of recently hired, entry-level professionals (employers) on how well their programs prepared them for career success (students and faculty) in those same job skills and academic topics. Critical thinking and written and oral communication skills topped the list of important skills and academic topics. Employers perceived recent entry-level hires to be less well-prepared to succeed in their careers than either university faculty or students. Entry-level hires with post-graduate degrees rated higher in proficiency for highly important skills and knowledge than those with bachelor’s degrees. We conclude that although universities have the primary responsibility for developing critical thinking and basic communication skills of students, employers have equal or greater responsibility for enhancing skills of employees in teamwork, field techniques, and communicating with stakeholders. The American Fisheries Society can significantly contribute to the preparation of young fisheries professionals by providing opportunities for continuing education and networking with peers at professional conferences. ¿Estamos preparando a la siguiente generación de profesionales en pesquerías para que tengan éxito en sus carreras?: una encuesta a miembros de la AFS Los profesionales de los recursos naturales, con frecuencia, han criticado a las universidades por la preparación deficiente de los graduados para tener éxito en sus trabajos. En este trabajo se encuestaron a miembros de la Sociedad Americana de Pesquerías para determinar qué conocimiento de tópicos académicos y habilidades laborales consideran los empleados, estudiantes y miembros de facultades universitarias como las más importantes en los profesionales de las pesquerías para tener éxito al inicio de sus carreras. Los encuestados también reconocieron las habilidades de los profesionistas regresados y contratados (empleados) o qué tan bien sus programas académicos los preparaban para tener éxito en sus carreras (estudiantes y facultad) en las mismas habilidades laborales y tópicos académicos. El pensamiento crítico y las habilidades de comunicación oral y escrita encabezaron la lista de habilidades y tópicos académicos importantes. Los empleadores percibieron a las contrataciones recientes como menos preparadas para tener éxito en sus carreras que los miembros de la facultad o los propios estudiantes. Los individuos recién contratados con posgrado fueron mejor calificados en cuanto a poseer el conocimiento y las habilidades más importantes que los titulados de licenciatura. Concluimos que si bien las universidades tienen la responsabilidad primordial de desarrollar el pensamiento crítico y las habilidades de comunicación en los estudiantes, los empleadores tienen la misma o mayor responsabilidad para fomentar las habilidades de sus trabajadores en lo referente a trabajo en equipo, técnicas de trabajo en campo, y comunicación con los involucrados en las pesquerías. La Sociedad Americana de Pesquerías puede contribuir significativamente a preparar a los jóvenes profesionistas de las pesquerías mediante el otorgamiento de oportunidades para continuar con su educación y el establecimiento de redes de contactos, durante conferencias, con pares y profesionales. Préparons-nous la prochaine génération de professionnels de la pêche à réussir leur carrière?: Un sondage auprès des membres AFS Les professionnels des ressources naturelles ont fréquemment critiqué les universités, car elles préparent mal les diplômés à réussir leur carrière. Nous avons interrogé les membres de l’American Fisheries Society pour déterminer quelles compétences professionnelles et quelles connaissances académiques les employeurs, étudiants et membres du corps professoral des universités jugent les plus importantes pour le succès des professionnels de la pêche au début de leur carrière. Les répondants ont également évalué l’aptitude des professionnels récemment entrés sur le marché du travail (employeurs) ou dans quelle mesure les programmes les ont préparés à réussir leur carrière (étudiants et professeurs) dans ces mêmes compétences professionnelles et sujets académiques. La pensée critique, les compétences en communication écrite et orale étaient en tête de la liste des compétences et des sujets académiques importants. Les employeurs ont perçu les professionnels récemment entrés sur le marché du travail moins bien préparés pour réussir dans leur carrière que les professeurs d’université ou les étudiants. Les employés au niveau d’entrée possédant des diplômes postuniversitaires étaient mieux notés dans la maîtrise des compétences et des connaissances très importantes que ceux ne possédant que des diplômes de baccalauréat. Nous concluons que, bien que les universités aient la responsabilité principale de développer la pensée critique et les compétences en communication de base des étudiants, les employeurs ont la responsabilité égale ou supérieure d’améliorer ces compétences dans le travail d’équipe, les techniques de terrain et la communication avec les parties prenantes. L’American Fisheries Society peut contribuer de manière significative à la préparation des jeunes professionnels de la pêche en offrant des possibilités de formation continue et de réseautage avec des pairs lors de conférences professionnelles

Determination of the (3x3)-Sn/Ge(111) structure by photoelectron diffraction

At a coverage of about 1/3 monolayer, Sn deposited on Ge(111) below 550 forms a metastable (sqrt3 x sqrt3)R30 phase. This phase continuously and reversibly transforms into a (3x3) one, upon cooling below 200 K. The photoemission spectra of the Sn 4d electrons from the (3x3)-Sn/Ge(111) surface present two components which are attributed to inequivalent Sn atoms in T4 bonding sites. This structure has been explored by photoelectron diffraction experiments performed at the ALOISA beamline of the Elettra storage ring in Trieste (Italy). The modulation of the intensities of the two Sn components, caused by the backscattering of the underneath Ge atoms, has been measured as a function of the emission angle at fixed kinetic energies and viceversa. The bond angle between Sn and its nearest neighbour atoms in the first Ge layer (Sn-Ge1) has been measured by taking polar scans along the main symmetry directions and it was found almost equivalent for the two components. The corresponding bond lengths are also quite similar, as obtained by studying the dependence on the photoelectron kinetic energy, while keeping the photon polarization and the collection direction parallel to the Sn-Ge1 bond orientation (bond emission). A clear difference between the two bonding sites is observed when studying the energy dependence at normal emission, where the sensitivity to the Sn height above the Ge atom in the second layer is enhanced. This vertical distance is found to be 0.3 Angstroms larger for one Sn atom out of the three contained in the lattice unit cell. The (3x3)-Sn/Ge(111) is thus characterized by a structure where the Sn atom and its three nearest neighbour Ge atoms form a rather rigid unit that presents a strong vertical distortion with respect to the underneath atom of the second Ge layer.Comment: 10 pages with 9 figures, added reference

COVID-19 Roundtable

The past year was an unprecedentedly challenging period to humanity. The very concept of a pandemic indicates a profound impact across different regions and societal strata, rendering the idea of unscathed human lives almost unimaginable. Still, this image of COVID-19 as a global threat menacing us all must not be allowed to efface the specificity of individual or communal struggles. This caveat is particularly relevant in the context of gender and diversity studies – the pertinence of which has been underscored countlessly over the past months, especially in policy recommendations to the COVID-19 pandemic. From the disproportionately severe measures aggravating isolation and destitution among the elderly to the coalescence of sanitary regulations and the BLM protests or the fire in the Moria refugee camp and the resulting urgency to address the wellbeing of displaced people: issues that relate intimately to notions of marginalization continually surface adjacent to the health crisis proper. Whether explicitly or implicitly, these circumstances call for gender and diversity scholars to commit their expertise to the benefit of those inordinately affected by COVID-19 and the array of responses it has evoked worldwide. At the same time, the conditions affecting these groups and individuals also affect research activities and advocacy work on gender and diversity, inhibiting the active commitment and scholarly involvement the situation demands. In this Spring 2021 General Issue, the Journal of Diversity and Gender Studies (DiGeSt) sought to explore the paradoxes, contradictions and tensions scholars in our field have faced and continue to face during the current COVID-19 crisis. Transcending a formally academic register, the roundtable includes personal, situated accounts that engage tensions between the pandemic and scholarly work in diversity and gender studies

Deformation effects in 56^{56}Ni nuclei produced in 28^{28}Si+28^{28}Si at 112 MeV

Velocity and energy spectra of the light charged particles (protons and $\alpha$-particles) emitted in the $^{28}$Si(E$_{lab}$ = 112 MeV) + $^{28}$Si reaction have been measured at the Strasbourg VIVITRON Tandem facility. The ICARE charged particle multidetector array was used to obtain exclusive spectra of the light particles in the angular range 15 - 150 degree and to determine the angular correlations of these particles with respect to the emission angles of the evaporation residues. The experimental data are analysed in the framework of the statistical model. The exclusive energy spectra of $\alpha$-particles emitted from the $^{28}$Si + $^{28}$Si compound system are generally well reproduced by Monte Carlo calculations using spin-dependent level densities. This spin dependence approach suggests the onset of large deformations at high spin. A re-analysis of previous $\alpha$-particle data from the $^{30}$Si + $^{30}$Si compound system, using the same spin-dependent parametrization, is also presented in the framework of a general discussion of the occurrence of large deformation effects in the A$_{CN}$ ~ 60 mass region.Comment: 25 pages, 6 figure