A multi-faceted comparative perspective on elevational beta-diversity: the patterns and their causes

The observed patterns and underlying mechanisms of elevational beta-diversity have been explored intensively, but multi-dimensional comparative studies remain scarce. Herein, across distinct beta-diversity components, dimensions and species groups, we designed a multi-faceted comparative framework aiming to reveal the general rules in the observed patterns and underlying causes of elevational beta-diversity. We have found that: first, the turnover process dominated altitudinal patterns of species beta-diversity ( β sim > β sne ), whereas the nestedness process appeared relatively more important for elevational trait dissimilarity ( β funcsim < β funcsne ); second, the taxonomic turnover was relative higher than its phylogenetic and functional analogues ( β sim > β phylosim / β funcsim ), conversely, nestedness-resultant trait dissimilarity tended to be higher than the taxonomic and phylogenetic measures ( β funcsne > β sne / β phylosne ); and third, as elevational distance increased, the contradicting dynamics of environmental filtering and limiting similarity have jointly led the elevational patterns of beta-diversity, especially at taxonomic dimension. Based on these findings, we infer that the species turnover among phylogenetic relatives sharing similar functional attributes appears to be the main cause of shaping the altitudinal patterns of multi-dimensional beta-diversity. Owing to the methodological limitation in the randomization approach, currently, it remains extremely challenging to distinguish the influence of the neutral process from the offset between opposing niche-based processes. Despite the complexities and uncertainties during species assembling, with a multi-dimensional comparative perspective, this work offers us several important commonalities of elevational beta-diversity dynamics.

Establishment of a new sex-determining allele driven by sexually antagonistic selection

The turnover of sex-determining loci has repeatedly occurred in a number of species, rather than having a diverged pair of sex chromosomes. We model the turnover process by considering a linked locus under sexually antagonistic selection. The entire process of a turnover may be divided into two phases, which are referred to as the stochastic and deterministic phases. The stochastic phase is when a new sex-determining allele just arises and is still rare and random genetic drift plays an important role. In the deterministic phase, the new allele further increases in frequency by positive selection. The theoretical results currently available are for the deterministic phase, which demonstrated that a turnover of a newly arisen sex-determining locus could benefit from selection at a linked locus under sexually antagonistic selection, by assuming that sexually antagonistic selection works in a form of balancing selection. In this work, we provide a comprehensive theoretical description of the entire process from the stochastic phase to the deterministic phase. In addition to balancing selection, we explore several other modes of selection on the linked locus. Our theory allows us make a quantitative argument on the rate of turnover and the effect of the mode of selection at the linked locus. We also performed simulations to explore the pattern of polymorphism around the new sex-determining locus. We find that the pattern of polymorphism is informative to infer how selection worked through the turnover process.

Establishment of a new sex-determining allele driven by sexually antagonistic selection

ABSTRACTSome species undergo frequent turnovers of sex-determining locus, rather than having stable diverged sex chromosomes. In such species, how often turnover occurs is a fundamental evolutionary question. We model the process with considering a linked locus under sexually antagonistic selection. The entire process of a turnover may be divided into two phases, which are referred to as the stochastic and deterministic phases. The stochastic phase is when a new sex-determining allele just arises and is still rare and random genetic drift plays an important role. In the deterministic phase, the new allele further increases in frequency by positive selection. The theoretical results currently available are for the deterministic phase, which demonstrated that a turnover of a newly arisen sex determining locus could benefit from selection at a linked locus under sexually antagonistic selection, by assuming that sexually antagonistic selection works in a form of balancing selection. In this work, we provide a comprehensive theoretical description of the entire process from the stochastic phase to the deterministic phase. In addition to balancing selection, we explore several other modes of selection on the linked locus. Our theory allows us make a quantitative argument on the rate of turnover and the effect of the mode of selection at the linked locus. We also performed simulations to explore the pattern of polymorphism around the new sex determining locus. We find that the pattern of polymorphism is informative to infer how selection worked through the turnover process.

Connexin 43 in osteogenesis

Skeleton formation and its proper functioning is possible thanks to specialized bone tissue cells: bone forming osteoblasts, bone resorbing osteoclasts and osteocytes located in bone cavities. Gap junctions are transmembrane channels connecting neighboring cell. Thanks to gap junctions it is possible for signals to be directly transmitted by cells. Gap junction type channels, and more specifically the connexin proteins that build them, have a key impacton the bone turnover process, and thus on both bone building and remodeling. A particularly important connexin in bone tissue is connexin43 (Cx43), which is necessary in the proper course of the bone formation process and in maintaining bone homeostasis. The importance of the presence of Cx43 in bones is showed by skeletal defects in diseases such as ODD syndrome and craniometaphyseal dysplasia caused by mutations in GJA1, the gene encoding Cx43. The role of Cx43 in the differentiation of stem cells into bone cells, anti-apoptotic action of bisphosphonates and bone responses to hormonal and mechanical stimuli have also been demonstrated. In addition to connexin43, the presence of other connexins such as connexin45, 46 and 37 was also noted in bone tissue.

Aerobic C–H Functionalization Using Pyrenedione as the Photocatalyst

We disclose a visible-light-promoted aerobic alkylation of activated C(sp3)–H bonds using pyrenedione (PYD) as the photocatalyst. Direct C–H bond alkylation of tetrahydrofuran with alkylidenemalononitriles is accomplished in over 90% yield in the presence of 5 mol% of PYD and 18 W blue LED light under ambient conditions. The substrate scope is extended to ethers, thioethers, and allylic C–H bonds in reactions with various electrophilic Michael acceptors. The catalytic turnover process is facilitated by oxygen. Our work represents the first example of using PYD as a photocatalyst to promote C(sp3)–H alkylation, revealing the unique character of PYD as a novel organophotocatalyst.

CAUSATIVE ASPECTS OF TRADE TURNOVER: A MANAGERS AND EMPLOYEES’ PERCEPTION

The objective of this study was to identify the causes of the turnover process in the city of Viçosa-AL. For this, it was held a descriptive and qualitative study aiming to identify, by means of the perception of managers and contributors, the reasons for process of turnover of micro and small businesses in the commercial sector. It was identified that elements of professional qualification, existence of new job opportunities, quality of life at work, perception of success in the career and the process of recruitment and selection influence on the process of turnover. The age element has demonstrated not to be an influencer on this process. Findings of the study also identified that the satisfaction at work, dissatisfaction with the manager, bad resourcefulness as a professional and discontinuity in the rhythm of work also contribute to the turnover process. A managers' contribution to this study was helping to elencare the main flaws of controlling the process of turnover in trade in a vision from collaborators and managers, showing both sides of the working relationship. From an academic point of view, this study collaborates with the understanding of the turnover process, offering two visions - supposedly antagonistic -, besides conducting a research in trade without restriction of business branches. As a contribution to future studies, there is a suggestion of deeping the question embracing other sectors to verify if there is a difference in the managers and employees’ perception from different sectors.

Oxidative and non-oxidative active turnover of genomic methylcytosine in distinct pluripotent states

Epigenetic plasticity underpins cell potency, but the extent to which active turnover of DNA methylation contributes to such plasticity is not known and the underlying pathways are poorly understood. Here we use metabolic labelling with stable isotopes and mass spectrometry to quantitatively address the global turnover of genomic methylcytidine (mdC), hydroxymethylcytidine (hmdC) and formylcytidine (fdC) across mouse pluripotent cell states. High rates of mdC/hmdC oxidation and fdC turnover characterize a formative-like pluripotent state. In primed pluripotent cells the global mdC turnover rate is about 3-6% faster than can be explained by passive dilution through DNA synthesis. While this active component is largely dependent on Tet-mediated mdC oxidation, we unveiled an additional mdC oxidation-independent turnover process based on DNA repair. This process accelerates upon acquisition of primed pluripotency and returns to low levels in lineage committed cells. Thus, in pluripotent cells active mdC turnover involves both mdC oxidation-dependent and -independent processes.

Molecular understanding of pharmacological treatment of osteoporosis

Osteoporosis is a serious health concern, particularly in aged societies. The burden of osteoporosis with its associated morbidity and mortality due to fracture has become a critical socioeconomic problem. Skeletal integrity is maintained through a balance of bone resorption and bone formation. The bone turnover process, called bone remodelling. Recently, a number of anti-osteoporosis drugs with excellent anti-osteoporosis and fracture effects have been developed. They are mainly classified into two groups according to their effects on bone remodelling: anti-resorptive agents and anabolic agents. Cite this article: EFORT Open Rev 2019;4:158-164. DOI: 10.1302/2058-5241.4.180018

SENSORY ANALYSIS OF COFFEE DRIED IN YARD WITH AND WITHOUT STIRRING

<p>The production of quality coffees, with different sensory characteristics, is strongly related to drying techniques. Experiments were carried out on coffee fruits, with the presence and absence of the fruit turnover process during drying in the yard, Catuaí Vermelho 144 coffee fruits, from the Cerrado Mineiro, processed dry and wet. The treatments consisted of natural parchment, natural green, peeled parchment and demucilated parchment fruits, which were dried in a concrete yard. They were conducted in a completely randomized design, with 4 post-harvest processes, 2 types of drying (with or without tillage) and 3 replications, totaling 24 plots. Natural green and natural parchment coffees were more responsive in the final scores, when not stirred during the drying process in the yard, unlike the coffees obtained by wet processing. Peeled coffees obtained the highest scores for the attributes, regardless of the adoption or not of stirring during the drying process in the yard. It was possible to obtain scores above 80 points by the SCA protocol, without stirring the coffee in the yard.</p>