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"Apse"
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JIYEH CHURCH, SOUTH OF BEIRUT- LEBANON: ARCHITECTURAL STUDY
2024
With the declaration of Christianity as the official religion of the Byzantine state in the year 381 AD, a campaign of destruction of the ancient temples spread throughout the Roman Empire. Their stones and columns were used to build cathedrals and Christian churches, distinguished by their designs. Some of those temples, distinguished by their architecture and tall buildings, were transformed into centers of worship appropriate to the new religion. These churches did not remain as they were because of their exposure in subsequent eras to destruction, especially the earthquakes(·) that struck the region and the successive wars(··) and the looting and vandalism that accompanied them. In the sixth century AD, religious divisions increased, a Syriac cultural renaissance appeared, and loyalty to the Byzantine state weakened until it faded away in the seventh century AD. The state exhausted its resources and lost many lands during the Islamic conquests, and the empire lost its most important provinces, including this region. Among the important examples are the churches of Lebanon; one of them being the \"Jiyeh church\"
Journal Article
Phage loss and the breakdown of a defensive symbiosis in aphids
by
Weldon, S. R.
,
Oliver, K. M.
,
Strand, M. R.
in
Acyrthosiphon pisum
,
Analysis of Variance
,
Animals
2013
Terrestrial arthropods are often infected with heritable bacterial symbionts, which may themselves be infected by bacteriophages. However, what role, if any, bacteriophages play in the regulation and maintenance of insect–bacteria symbioses is largely unknown. Infection of the aphid Acyrthosiphon pisum by the bacterial symbiont Hamiltonella defensa confers protection against parasitoid wasps, but only when H. defensa is itself infected by the phage A. pisum secondary endosymbiont (APSE). Here, we use a controlled genetic background and correlation-based assays to show that loss of APSE is associated with up to sevenfold increases in the intra-aphid abundance of H. defensa. APSE loss is also associated with severe deleterious effects on aphid fitness: aphids infected with H. defensa lacking APSE have a significantly delayed onset of reproduction, lower weight at adulthood and half as many total offspring as aphids infected with phage-harbouring H. defensa, indicating that phage loss can rapidly lead to the breakdown of the defensive symbiosis. Our results overall indicate that bacteriophages play critical roles in both aphid defence and the maintenance of heritable symbiosis.
Journal Article
Hamiltonella defensa, genome evolution of protective bacterial endosymbiont from pathogenic ancestors
2009
Eukaryotes engage in a multitude of beneficial and deleterious interactions with bacteria. Hamiltonella defensa, an endosymbiont of aphids and other sap-feeding insects, protects its aphid host from attack by parasitoid wasps. Thus H. defensa is only conditionally beneficial to hosts, unlike ancient nutritional symbionts, such as Buchnera, that are obligate. Similar to pathogenic bacteria, H. defensa is able to invade naive hosts and circumvent host immune responses. We have sequenced the genome of H. defensa to identify possible mechanisms that underlie its persistence in healthy aphids and protection from parasitoids. The 2.1-Mb genome has undergone significant reduction in size relative to its closest free-living relatives, which include Yersinia and Serratia species (4.6-5.4 Mb). Auxotrophic for 8 of the 10 essential amino acids, H. defensa is reliant upon the essential amino acids produced by BUCHNERA: Despite these losses, the H. defensa genome retains more genes and pathways for a variety of cell structures and processes than do obligate symbionts, such as BUCHNERA: Furthermore, putative pathogenicity loci, encoding type-3 secretion systems, and toxin homologs, which are absent in obligate symbionts, are abundant in the H. defensa genome, as are regulatory genes that likely control the timing of their expression. The genome is also littered with mobile DNA, including phage-derived genes, plasmids, and insertion-sequence elements, highlighting its dynamic nature and the continued role horizontal gene transfer plays in shaping it.
Journal Article
The diversity and fitness effects of infection with facultative endosymbionts in the grain aphid, Sitobion avenae
by
Dawid, Maciej A.
,
Łukasik, Piotr
,
Godfray, H. Charles J.
in
Analysis
,
Animal and plant ecology
,
Animal, plant and microbial ecology
2013
Mutualisms with facultative, non-essential heritable microorganisms influence the biology of many insects, and they can have major effects on insect host fitness in certain situations. One of the best-known examples is found in aphids where the facultative endosymbiotic bacterium Hamiltonella defensa confers protection against hymenopterous parasitoids. This symbiont is widely distributed in aphids and related insects, yet its defensive properties have only been tested in two aphid species. In a wild population of the grain aphid, Sitobion avenae, we identified several distinct strains of endosymbiotic bacteria, including Hamiltonella. The symbiont had no consistent effect on grain aphid fecundity, though we did find a significant interaction between aphid genotype by symbiont status. In contrast to findings in other aphid species, Hamiltonella did not reduce aphid susceptibility to two species of parasitoids (Aphidius ervi and Ephedrus plagiator), nor did it affect the fitness of wasps that successfully completed development. Despite this, experienced females of both parasitoid species preferentially oviposited into uninfected hosts when given a choice between genetically identical individuals with or without Hamiltonella. Thus, although Hamiltonella does not always increase resistance to parasitism, it may reduce the risk of parasitism in its aphid hosts by making them less attractive to searching parasitoids.
Journal Article
A Coupled Thermal–Hydrological–Mechanical Damage Model and Its Numerical Simulations of Damage Evolution in APSE
2016
This paper proposes a coupled thermal–hydrological–mechanical damage (THMD) model for the failure process of rock, in which coupling effects such as thermally induced rock deformation, water flow-induced thermal convection, and rock deformation-induced water flow are considered. The damage is considered to be the key factor that controls the THM coupling process and the heterogeneity of rock is characterized by the Weibull distribution. Next, numerical simulations on excavation-induced damage zones in Äspö pillar stability experiments (APSE) are carried out and the impact of in situ stress conditions on damage zone distribution is analysed. Then, further numerical simulations of damage evolution at the heating stage in APSE are carried out. The impacts of in situ stress state, swelling pressure and water pressure on damage evolution at the heating stage are simulated and analysed, respectively. The simulation results indicate that (1) the v-shaped notch at the sidewall of the pillar is predominantly controlled by the in situ stress trends and magnitude; (2) at the heating stage, the existence of confining pressure can suppress the occurrence of damage, including shear damage and tensile damage; and (3) the presence of water flow and water pressure can promote the occurrence of damage, especially shear damage.
Journal Article
Venus Magnetotail Long-Term Sensing Using Solar Sails
2024
Propellantless propulsion systems, such as the well-known photonic solar sails that provide thrust by exploiting the solar radiation pressure, theoretically allow for extremely complex space missions that require a high value of velocity variation to be carried out. Such challenging space missions typically need the application of continuous thrust for a very long period of time, compared to the classic operational life of a space vehicle equipped with a more conventional propulsion system as, for example, an electric thruster. In this context, an interesting application of this propellantless thruster consists of using the solar sail-induced acceleration to artificially precess the apse line of a planetocentric elliptic orbit. This specific mission application was thoroughly investigated about twenty years ago in the context of the GeoSail Technology Reference Study, which analyzed the potential use of a spacecraft equipped with a small solar sail to perform an in situ study of the Earth’s upper magnetosphere. Taking inspiration from the GeoSail concept, this study analyzes the performance of a solar sail-based spacecraft in (artificially) precessing the apse line of a high elliptic orbit around Venus with the aim of exploring the planet’s induced magnetotail. In particular, during flight, the solar sail orientation is assumed to be Sun-facing, and the required thruster’s performance is evaluated as a function of the elliptic orbit’s characteristics by using both a simplified mathematical model of the spacecraft’s planetocentric dynamics and an approximate analytical approach. Numerical results show that a medium–low-performance sail is able to artificially precess the apse line of a Venus-centered orbit in order to ensure the long-term sensing of the planet’s induced magnetotail.
Journal Article
The Transcription Factor StuA Regulates the Glyoxylate Cycle in the Dermatophyte Trichophyton rubrum under Carbon Starvation
by
Rossi, Antonio
,
Martinez-Rossi, Nilce M.
,
Petrucelli, Monise Fazolin
in
Alternative Splicing
,
Arthrodermataceae
,
Carbon
2023
Trichophyton rubrum is the primary causative agent of dermatophytosis worldwide. This fungus colonizes keratinized tissues and uses keratin as a nutritional source during infection. In T. rubrum–host interactions, sensing a hostile environment triggers the adaptation of its metabolic machinery to ensure its survival. The glyoxylate cycle has emerged as an alternative metabolic pathway when glucose availability is limited; this enables the conversion of simple carbon compounds into glucose via gluconeogenesis. In this study, we investigated the impact of stuA deletion on the response of glyoxylate cycle enzymes during fungal growth under varying culture conditions in conjunction with post-transcriptional regulation through alternative splicing of the genes encoding these enzymes. We revealed that the ΔstuA mutant downregulated the malate synthase and isocitrate lyase genes in a keratin-containing medium or when co-cultured with human keratinocytes. Alternative splicing of an isocitrate lyase gene yielded a new isoform. Enzymatic activity assays showed specific instances where isocitrate lyase and malate synthase activities were affected in the mutant strain compared to the wild type strain. Taken together, our results indicate a relevant balance in transcriptional regulation that has distinct effects on the enzymatic activities of malate synthase and isocitrate lyase.
Journal Article
Planetary nodes and apses in the Sūrya-Siddhānta
2023
There are a few aspects of Indian astronomy that border on the implausible, and none more so than the nodal and apsidal movements of planetary orbits as specified in the
Sūrya-Siddhānta
. In this paper we examine some aspects of this data in the light of modern astronomy. Given the very-slow rates of motion specified for these two parameters, we speculate that this data might be heliocentric (as opposed to geocentric), and proceed with that assumption in this paper. It is determined that while this assumption proves true for the outer planets (Mars, Jupiter and Saturn), it does not conform well with the inner planets (Mercury and Venus). It is also determined that while the directions specified in the
Sūrya-Siddhānta
for these subtle motions are correct, the rates of motion given are slower by a couple orders of magnitude compared to actuality. Further analysis also appears to confirm that the data is genuine, and the epoch of the data is likely many thousands of years old.
Journal Article
Characterization of the mbsA Gene Encoding a Putative APSES Transcription Factor in Aspergillus fumigatus
by
Yu, Jae-Hyuk
,
Choi, Yong-Ho
,
Lee, Min-Woo
in
Amino acids
,
Asexuality
,
Aspergillus fumigatus - genetics
2021
The APSES family proteins are transcription factors (TFs) with a basic helix-loop-helix domain, known to regulate growth, development, secondary metabolism, and other biological processes in Aspergillus species. In the genome of the human opportunistic pathogenic fungus Aspergillus fumigatus, five genes predicted to encode APSES TFs are present. Here, we report the characterization of one of these genes, called mbsA (Afu7g05620). The deletion (Δ) of mbsA resulted in significantly decreased hyphal growth and asexual sporulation (conidiation), and lowered mRNA levels of the key conidiation genes abaA, brlA, and wetA. Moreover, ΔmbsA resulted in reduced spore germination rates, elevated sensitivity toward Nikkomycin Z, and significantly lowered transcripts levels of genes associated with chitin synthesis. The mbsA deletion also resulted in significantly reduced levels of proteins and transcripts of genes associated with the SakA MAP kinase pathway. Importantly, the cell wall hydrophobicity and architecture of the ΔmbsA asexual spores (conidia) were altered, notably lacking the rodlet layer on the surface of the ΔmbsA conidium. Comparative transcriptomic analyses revealed that the ΔmbsA mutant showed higher mRNA levels of gliotoxin (GT) biosynthetic genes, which was corroborated by elevated levels of GT production in the mutant. While the ΔmbsA mutant produced higher amount of GT, ΔmbsA strains showed reduced virulence in the murine model, likely due to the defective spore integrity. In summary, the putative APSES TF MbsA plays a multiple role in governing growth, development, spore wall architecture, GT production, and virulence, which may be associated with the attenuated SakA signaling pathway.
Journal Article
3D SURVEYING AND FORMAL ANALYSIS OF A STRUCTURAL BAY OF A GOTHIC APSE
2022
In recent years, the development of massive data capture techniques such as Terrestrial Laser Scanner (TLS) have made it possible to develop new procedures to evaluate architectural heritage with a high level of accuracy. The study proposes a workflow to identify formal anomalies in the main elements that form a structural bay of the apse of the Cathedral of Girona, studying arches, vaults, buttresses and pillars. The methodology is based on different two-dimensional and three-dimensional procedures, and the database obtained that could help in future research to relate the results with the different construction phases and being applicable to other constructions of similar typology.
Journal Article