Evolution of Photosynthesis and Biospheric Oxygenation Contingent Upon Nitrogen Fixation?

How photosynthesis by Precambrian cyanobacteria oxygenated Earth's biosphere remains incompletely understood. Here it is argued that the oxic transition, which took place between approximately 2.3 and 0.5 Gyr ago, required a great proliferation of cyanobacteria, and this in turn depended on their ability to fix nitrogen via the nitrogenase enzyme system. However, the ability to fix nitrogen was not a panacea, and the rate of biospheric oxygenation may still have been affected by nitrogen constraints on cyanobacterial expansion. Evidence is presented for why cyanobacteria probably have a great need for fixed nitrogen than other prokaryotes, underscoring the importance of their ability to fix nitrogen. The connection between nitrogen fixation and the evolution of photosynthesis is demonstrated by the similarities between nitrogenase and enzymes critical for the biosynthesis of (bacterio)chlorophyll. It is hypothesized that biospheric oxygenation would not have occurred if the emergence of cyanobacteria had not been preceded by the evolution of nitrogen fixation, and if these organisms had not also acquired the ability to fix nitrogen at the beginning of or very early in their history. The evolution of nitrogen fixation also appears to have been a precondition for the evolution of (bacterio)chlorophyll-based photosynthesis. Given that some form of chlorophyll is obligatory for true photosynthesis, and its light absorption and chemical properties make it a "universal pigment," it may be predicted that the evolution of nitrogen fixation and photosynthesis are also closely linked on other Earth- like planets.Comment: 15 pages, 1 figur

Komunikacijski model kampanje »Međimurje daje više«, s ciljem smanjenja negativnih utjecaja pandemije COVID 19 virusa na turističke rezultate Međimurske županije

The paper deals with the communication model and the results achieved by the campaign »Međimurje daje više«,(»Međimurje Gives More« led with the aim of reducing the negative economic consequences of the COVID 19 pandemic on the tourist results of Međimurje County from 15.6.2020 to 15.9.2020. The starting point is the fact that the outbreak of a pandemic plays an important role in the social habits of tourists and results in changes in their needs, but also the capabilities of providers and users of tourist services / offers. The paper identifies and analyzes the factors of the persuasive communication model that will positively influence the sustainable tourism and recovery of Međimurje as a tourist destination through nudge tools. The paper is based on descriptive and developmental research, descriptive methods of synthesis and analysis, comparisons, and the collected data are systematized and compared and qualitatively and quantitatively presented in tables and graphs. The central point of the paper is the thesis that the use of new, alternative communication models and tools is crucial for the crisis management, as well as professionalism of employees at all levels of the tourism industry.Rad se tematizira komunikacijski model i rezultate postignute kampanjom »Međimurje daje više« vođene s ciljem smanjenja negativnih ekonomskih posljedica pandemije bolesti COVID 19 virusa na turističke rezultate Međimurske županije od 15.6.2020. do 15.9.2020. Problematiziraju se i transformativne mogućnosti turizma zbog pandemije, uvođenjem persuativnog modela te nudge komunikacijskog alata, do sada rijetko korištenog na području turizma. Predviđanje, priprema i djelovanje s ciljem smanjenja posljedica krize izazvane COVID 19 virusom važan su izazov s kojim su suočene turističke destinacije u cijelom svijetu, a male su destinacije, poglavito ako je riječ o kontinentalnim destinacijama, s obzirom na ograničene financijske i ljudske kapacitete najugroženije. Polazišna osnova je činjenica da izbijanje bolesti pandemijskih razmjera igra važnu ulogu u društvenim i socijalnim navikama turista te rezultira promjenama potreba, ali i mogućnosti pružatelja i korisnika turističkih usluga/ponude. Temeljem dostupne literature u radu su identificirani i analizirani čimbenici persuazivnog komunikacijskog modela koji će kroz nudge alat pozitivno utjecati na održivi turizam i oporavak Međimurja kao turističkog odredišta koje, ako postignu očekivane rezultate kroz promatrano razdoblje od tri mjeseca, mogu dovesti do preusmjeravanja turizma te pridonijeti politikama održivog turizma primjenjivim i u drugim turističkim destinacijama. Rad je temeljen na deskriptivnom i razvojnom istraživanju, odnosno deskriptivnim metodama sinteze i analize, usporedbama, a prikupljeni podaci su sistematizirani i komparirani te kvalitativno i kvantitativno prikazani tabelarno i grafički. Središnja točka rada je teza kako je korištenje novih, alternativnih komunikacijskih modela i alata ključno za sanaciju i upravljanje kriznom situacijom u turizmu, a stručnost zaposlenika na svim razinama turističke industrije važna komponenta pripreme i upravljanja destinacijom za vrijeme i nakon krize izazvane bolešću COVID 19 virusa

Starotestamentowe antycypacje trynitarne w perspektywie motywu wielości w istocie Bóstwa

Celem niniejszego artykułu jest syntetyczne przedstawienie przesłanek starotestamentalnych, sugerujących istnienie w Bogu pewnych wielości, które w perspektywie Nowego Testamentu dają się nam odczytać jako działanie poszczególnych Osób Bożych. Analiza i zestawienie fragmentów Starego i Nowego Testamentu świadczy w perspektywie Bożych działań i Jego opisów, że na przestrzeni dziejów Bóg wnikał w życie ludzi zawsze w Osobach Ojca Syna i Ducha Świętego

Próba rehabilitacji pojęcia monoteletyzmu w świetle dedukcji wynikających z definicji osoby

This article concentrates on the teaching of the Third Council of Constantinopleregarding the assignment of two Natures of Christ and their two Wills. The first part focuses on the history of the Incarnation and Christological dogmas up until the Council. The second part, based on the understanding of the definition of the person, tries to explain how the Will, as the ability to make decisions and choices, is an act of personal rather than physical character, that in regard to human nature are influenced by biology, independently of our will. Therefore, the article seeks to explain that as the two Natures of Christ were united in the One Person of the Word Incarnate, so was Christ directed by One will belonging to his Person. However, that Will was also influenced by the afflictions of human nature. Therefore, Monothelitism can be rehabilitated when accepting that in Christ there is only One Will of the Person of the Son of God, in two united and properlycoordinated Natures

Molecular phylogeny of the Pectinoidea (Bivalvia) indicates Propeamussiidae to be a non-monophyletic family with one clade sister to the scallops (Pectinidae)

Scallops (Pectinidae) are one of the most diverse families of bivalves and have been a model system in evolutionary biology. However, in order to understand phenotypic evolution, the Pectinidae needs to be placed in a deeper phylogenetic framework within the superfamily Pectinoidea. We reconstructed a molecular phylogeny for 60 species from four of the five extant families within the Pectinoidea using a five gene dataset (12S, 16S, 18S, 28S rRNAs and histone H3). Our analyses give consistent support for the non-monophyly of the Propeamussiidae, with a subset of species as the sister group to the Pectinidae, the Propeamussiidae type species as sister to the Spondylidae, and the majority of propeamussiid taxa sister to the Spondylidae + Pr. dalli. This topology represents a previously undescribed relationship of pectinoidean families. Our results suggest a single origin for eyes within the superfamily and likely multiple instances of loss for these characters. However, it is now evident that reconstructing the evolutionary relationships of Pectinoidea will require a more comprehensive taxonomic sampling of the Propeamussiidae sensu lato

Female Drosophila melanogaster Gene Expression and Mate Choice: The X Chromosome Harbours Candidate Genes Underlying Sexual Isolation

Background: The evolution of female choice mechanisms favouring males of their own kind is considered a crucial step during the early stages of speciation. However, although the genomics of mate choice may influence both the likelihood and speed of speciation, the identity and location of genes underlying assortative mating remain largely unknown. Methods and Findings: We used mate choice experiments and gene expression analysis of female Drosophila melanogaster to examine three key components influencing speciation. We show that the 1,498 genes in Zimbabwean female D. melanogaster whose expression levels differ when mating with more (Zimbabwean) versus less (Cosmopolitan strain) preferred males include many with high expression in the central nervous system and ovaries, are disproportionately X-linked and form a number of clusters with low recombination distance. Significant involvement of the brain and ovaries is consistent with the action of a combination of pre- and postcopulatory female choice mechanisms, while sex linkage and clustering of genes lead to high potential evolutionary rate and sheltering against the homogenizing effects of gene exchange between populations. Conclusion: Taken together our results imply favourable genomic conditions for the evolution of reproductive isolation through mate choice in Zimbabwean D. melanogaster and suggest that mate choice may, in general, act as an even more important engine of speciation than previously realized

High-Resolution Genome-Wide Dissection of the Two Rules of Speciation in Drosophila

Postzygotic reproductive isolation is characterized by two striking empirical patterns. The first is Haldane's rule—the preferential inviability or sterility of species hybrids of the heterogametic (XY) sex. The second is the so-called large X effect—substitution of one species's X chromosome for another's has a disproportionately large effect on hybrid fitness compared to similar substitution of an autosome. Although the first rule has been well-established, the second rule remains controversial. Here, we dissect the genetic causes of these two rules using a genome-wide introgression analysis of Drosophila mauritiana chromosome segments in an otherwise D. sechellia genetic background. We find that recessive hybrid incompatibilities outnumber dominant ones and that hybrid male steriles outnumber all other types of incompatibility, consistent with the dominance and faster-male theories of Haldane's rule, respectively. We also find that, although X-linked and autosomal introgressions are of similar size, most X-linked introgressions cause hybrid male sterility (60%) whereas few autosomal introgressions do (18%). Our results thus confirm the large X effect and identify its proximate cause: incompatibilities causing hybrid male sterility have a higher density on the X chromosome than on the autosomes. We evaluate several hypotheses for the evolutionary cause of this excess of X-linked hybrid male sterility