Hasil untuk "Evolution"

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DOAJ Open Access 2025
High-Redshift Quasars at <i>z</i> ≥ 3—III: Parsec-Scale Jet Properties from Very Long Baseline Interferometry Observations

Shaoguang Guo, Tao An, Yuanqi Liu et al.

High-redshift active galactic nuclei (AGN) provide key insights into early supermassive black hole growth and cosmic evolution. This study investigates the parsec-scale properties of 86 radio-loud quasars at z ≥ 3 using very long baseline interferometry (VLBI) observations. Our results show predominantly compact core and core-jet morphologies, with 35% having unresolved cores, 59% with core–jet structures, and only 6% with core–double jet morphology. Brightness temperatures are generally lower than expected for highly radiative sources. The jets’ proper motions are surprisingly slow compared to those of lower-redshift samples. We observe a high fraction of young and/or confined peak-spectrum sources, providing insights into early AGN evolution in dense environments during early cosmic epochs. The observed trends may reflect genuine evolutionary changes in AGN structure over cosmic time, or selection effects favoring more compact sources at higher redshifts. These results stress the complexity of high-redshift radio-loud AGN populations and emphasize the need for multi-wavelength, high-resolution observations to fully characterize their properties and evolution through cosmic history.

Elementary particle physics
DOAJ Open Access 2025
THE EVOLUTION OF REPRODUCTIVE STRATEGIES IN ANIMALS – IMPLICATIONS FOR THERIOGENOLOGY

Klementina Fon Tacer, Gregor Majdič

Reproduction is one of the fundamental biological imperatives shared by all living beings. Organisms must reproduce to pass on their genes to the next generation, ensuring the survival and continuation of their species. In pursuit of this goal, nature has evolved a remarkable diversity of reproductive methods and behaviors, including external fertilization in aquatic species, internal fertilization in terrestrial animals, oviparity, viviparity, complex hormonal regulation, and diverse strategies of parental investment. In the Slovenian Veterinary Research journal, we welcome articles addressing various aspects of veterinary and comparative reproductive research and medicine. In this issue, we have placed particular emphasis on this topic. With this editorial, we would also like to bring attention to these articles, including a review of the phenomics evaluation and research on hormone GnRH injection in cattle and sheep breeding, the effect of food additives and environmental enrichment on fertility protection against toxicity  and egg production  and a case report on canine idiopathic oligoasthenoteratozoospermia. Razmnoževanje skozi prizmo evolucije – pomen za sodobno veterinarsko medicino Izvleček: Razmnoževanje je temelj življenja. Omogoča prenos genov na naslednje generacije in s tem ohranjanje vrst. Narava je skozi evolucijo razvila osupljivo paleto strategij, od zunanje oploditve pri vodnih organizmih do notranje oploditve pri kopenskih živalih, jajcerodnosti, živorodnosti, kompleksnega hormonskega uravnavanja in različnih oblik starševske skrbi. V reviji Slovenian Veterinary Research z veseljem objavljamo prispevke, ki obravnavajo različne vidike veterinarskih in primerjalnih raziskav ter medicine razmnoževanja. V tej številki smo temu področju namenili poseben poudarek. Predstavljamo prispevke, ki osvetljujejo fenomsko evalvacijo in raziskave vpliva hormona GnRH na plodnost goveda in ovc, vpliv prehranskih dodatkov in obogatitve okolja na zaščito plodnosti, in proizvodnjo jajc ter primer idiopatske oligoasteno-teratozoospermije pri psu.

Veterinary medicine
DOAJ Open Access 2025
Assessment of Ecological Carrying Capacity and Spatiotemporal Evolution Analysis for Arid Areas Based on the AHP-EW Model: A Case Study of Urumqi, China

Xiaoyan Tang, Funan Liu, Xinling Hu et al.

Ecological carrying capacity (ECC) is central to assessing the sustainability of ecosystems, aiming to quantify the limits of natural systems to support human activities while maintaining biodiversity and resource regeneration. To assess ECC, earlier studies typically used the analytic hierarchy process (AHP) method for modeling. In this study, we developed an AHP-EW method based on a combination of AHP and the entropy weight method, which considered important indicators including land use, vegetation, soil, location, topography, climate, and socio-economics, and constructed an ECC evaluation system. The new AHP-EW method was applied to analyze the spatiotemporal ECC patterns in Urumqi from 2000 to 2020. The results showed a general decreasing trend in ECC during the period 2000–2020. Among them, the ECC decreased significantly by 19.05% from 2000 to 2010. After 2010, the rate of decline in ECC slowed to 14.12% due to ecological conservation policies. In addition, Midong District, Dabancheng District, and Urumqi County had worse ECC. Still, in general, the distribution of ECC in each district and county showed a trend of decreasing in areas with low ECC and increasing in areas with high ECC. Cluster analysis showed that ECC improved in ecological reserve areas, while some built-up areas showed a decrease in ECC due to economic development and human activities. Driving factor analysis shows that NDVI, climate change, and land-use conversion are the key factors influencing the change in ECC in Urumqi. This study provides new ideas and technical support for ECC assessment in arid areas, which can help formulate more effective ecological protection strategies and promote the healthy and stable development of regional ecosystems.

DOAJ Open Access 2025
Dualism of the Aging Process (analytical review)

V. N. Shabalin

The aging process is one of the most complex problems in biology. Hundreds of research institutes around the world are studying aging at various levels of the structural organization of living matter. The results of many thousands of studies on this phenomenon have been published. More than 300 theories have been proposed that attempt to explain the causes of aging. It is important to note that almost all theories associate aging with the accumulation of negative changes in molecules and cells in the body. It seems that a person (or an individual of another biological species) lives in order to make negative changes in the structure of living matter. However, this contradicts the fact that damage and destructive changes cannot ensure progress in the evolutionary development of life. The article attempts to find the cause of this contradiction. The author puts forward a position on the dual function of the aging process in the development of living matter: on the one hand, aging causes degradation of the organism as a system, on the other, it ensures the structural improvement of its tissues at the molecular level. That is, aging, as the main mechanism of evolution, is aimed not at preserving the organism as a system, but at preserving its individual elements (information blocks) that are of interest for building new structures of living matter as a whole. An evolutionary ladder is formed from these information blocks, along which living matter rises to a higher level of its development. Aging is not decay or damage, but a mechanism for transferring one structure of living tissue to another - more perfect, with its preservation in the form of a potential phase for use by new cellular generations of the same organism or other organisms.

Medicine (General)
DOAJ Open Access 2025
A near-complete genome assembly of Fragaria iinumae

Haiyuan Du, Yiying He, Maoxian Chen et al.

Abstract Fragaria iinumae, a diploid progenitor species of octoploid strawberries, likely occupies a basal position within the genus Fragaria. In this study, we report a near-complete genome assembly of F. iinumae v2.0, totaling 241.14 Mb with a contig N50 of 33.31 Mb. We identified 14 telomeric and 7 centromeric regions across its seven chromosomes. Compared to previous assemblies, F. iinumae v2.0 demonstrates substantial improvements in both genome continuity (gaps reduced from 29 to 0) and annotation completeness, including the annotation of 4,144 new genes and 395 new gene clusters. Notably, several large structural variants were identified between the F. iinumae v1.0 and F. iinumae v2.0 genomes, with most gaps in the v1.0 assembly overlapping with structural variant breakpoints. Additionally, we found a significant expansion of telomeric repeats in the B subgenome of octoploid strawberries compared to F. iinumae. Interestingly, two telomeres consistently exhibited low repeat abundance in both the diploid and octoploid B subgenomes, suggesting significant contraction early in the evolution of F. iinumae. Furthermore, through multiple lines of genomic evidence—including phylogenetic analyses, genetic distance matrices, a burst of LTR insertions, and the distribution of NLR resistance genes, we conclude that F. iinumae may represent an early-diverging lineage within the strawberry genus. This updated assembly provides a crucial genomic resource for understanding of the origin and structural dynamics of the strawberry genus and facilitates further exploration of genome-wide consequences of polyploidy.

Biotechnology, Genetics
DOAJ Open Access 2024
Designing of high entropy alloys with high hardness: a metaheuristic approach

Ansh Poonia, Modalavalasa Kishor, Kameswari Prasada Rao Ayyagari

Abstract The near-infinite compositional space of high-entropy-alloys (HEAs) is a huge resource-intensive task for developing exceptional materials. In the present study, an algorithmic framework has been developed to optimize the composition of an alloy with chosen set of elements, aiming to maximize the hardness of the former. The influence of phase on hardness prediction of HEAs was thoroughly examined. This study aims to establish generalized prediction models that aren’t confined by any specific set of elements. We trained the HEA identification model to classify HEAs from non-HEAs, the multi-labeled phase classification model to predict phases of HEAs also considering the processing route involved in the synthesis of the alloy, and the hardness prediction model for predicting hardness and optimizing the composition of the given alloy. The purposed algorithmic framework uses twenty-nine alloy descriptors to compute the composition that demonstrates maximum hardness for the given set of elements along with its phase(s) and a label stating whether it is classified as HEA or not.

Medicine, Science
DOAJ Open Access 2023
Intracellular Transposition of Mobile Genetic Elements Associated with the Colistin Resistance Gene mcr-1

Richard N. Goodman, Supathep Tansirichaiya, Michael S. M. Brouwer et al.

ABSTRACT Mobile colistin resistance (mcr) genes are often located on conjugative plasmids, where their association with insertion sequences enables intercellular and intracellular dissemination throughout bacterial replicons and populations. Multiple mcr genes have been discovered in every habitable continent, in many bacterial species, on both plasmids and integrated into the chromosome. Previously, we showed the intercellular transfer of mcr-1 on an IncI1 plasmid, pMCR-E2899, between strains of Escherichia coli. Characterizing the intracellular dynamics of mcr-1 transposition and recombination would further our understanding of how these important genes move through bacterial populations and whether interventions can be put in place to stop their spread. In this study, we aimed to characterize transfer events from the mcr-1-containing transposon Tn7511 (ISApl1-mcr-1-pap2-ISApl1), located on plasmid pMCR-E2899, using the pBACpAK entrapment vector. Following the transformation of pBACpAK into our DH5α-Azir/pMCR-E2899 transconjugant, we captured ISApl1 in pBACpAK multiple times and, for the first time, observed the ISApl1-mediated transfer of the mcr-1 transposon (Tn7511) into the chromosome of E. coli DH5α. Whole-genome sequencing allowed us to determine consensus insertion sites of ISApl1 and Tn7511 in this strain, and comparison of these sites allowed us to explain the transposition events observed. These observations reveal the consequences of ISApl1 transposition within and between multiple replicons of the same cell and show mcr-1 transposition within the cell as part of the novel transposon Tn7511. IMPORTANCE By analyzing the intracellular transfer of clinically relevant transposons, we can understand the dissemination and evolution of drug resistance conferring mobile genetic elements (MGEs) once a plasmid enters a cell following conjugation. This knowledge will help further our understanding of how these important genes move through bacterial populations. Utilizing the pBACpAK entrapment vector has allowed us to determine the mobility of the novel mcr-1-containing transposon Tn7511.

DOAJ Open Access 2023
Key Factors of the Strong Cold Wave Event in the Winter of 2020/21 and Its Effects on the Predictability in CMA-GEPS

Pengfei Ren, Li Gao, Jiawen Zheng et al.

During the 2020/2021 winter season, three nationwide cold waves took place from 28 to 31 December 2020, as well as from 5 to 8 January and 14 to 17 January 2021. These cold waves resulted in extreme cold weather in northern and eastern China. In this study, the common features of these cold waves were analyzed, and the key factors contributing to cold waves were illustrated, and the performance of the CMA-GEPS numerical model was evaluated in predicting the cooling effect of the cold waves, and its predictability source was discussed. The results indicated that the cold waves were caused by synergistic effects in the mid- to high-latitude atmospheric circulation of both the upper and lower atmosphere, including polar vortex splitting, enhancement of blocking high, and increased meridional circulation anomaly in the Siberian high area. During the time of cold waves, the mid- to high-latitude atmospheric circulation was undergoing low-frequency adjustment, with the Arctic oscillation continuously weakening, while the blocking high and Siberian high gradually increased to historically high-intensity states. The outbreaks of the three cold waves occurred at the peak and declining points of the blocking high and Siberian high, respectively, acting as short- to medium-term forecast factors. The CMA-GEPS model demonstrated high forecasting ability for the cooling of the cold waves due to its ability to accurately predict the evolution of the Siberian high and blocking high prior to and after the cold wave with a long lead time. Predictability analysis suggested the strong variability of key factors (such as the Siberian high and blocking) in cold wave events may benefit the model’s prediction of cold wave events. These findings contribute to the understanding of the physical mechanisms behind cold waves and the potential for improved forecasting of extreme cold weather events.

Meteorology. Climatology
DOAJ Open Access 2023
On catching the preparatory phase of damaging earthquakes: an example from central Italy

Matteo Picozzi, Antonio G. Iaccarino, Daniele Spallarossa et al.

Abstract How, when and where large earthquakes are generated remain fundamental unsolved scientific questions. Intercepting when a fault system starts deviating from its steady behavior by monitoring the spatio-temporal evolution and dynamic source properties of micro-to-small earthquakes can have high potential as tool for identifying the preparatory phase of large earthquakes. We analyze the seismic activity that preceded the Mw 6.3 earthquake that hit L’Aquila on 6 April 2009 in central Italy, and we show that the seismic catalog information can be transformed into features allowing us to track in a statistical framework the spatio-temporal evolution of seismicity. Features associated to foreshocks show different patterns from the background seismicity that occurred in the previous years. We show that features ensemble allows to clearly capture the activation phase of the main event. Nonetheless, foreshocks share similar clustering properties of previous seismic sequences not culminating in large earthquakes, and thus generating questions on their use as potential precursor for earthquake sequences prone to evolve into catastrophic sequences.

Medicine, Science
DOAJ Open Access 2022
Numerical simulation on movement behavior of dispersed phase droplets of water-in-oil emulsion under electric field

HUANG Ya'nan, HOU Lei, XIAO Kaixi et al.

To explore the demulsification mechanism of emulsion under electric fields, the movement process of dispersed phase droplets in water-in-oil emulsion was simulated with the finite element method. Herein, the oil-water distribution was represented with the phase field method, and the accuracy and efficiency of calculation on fluid flow process was improved with the structured quadrilateral grid. Besides, the influence laws of electric field parameters, as well as the physical parameters of emulsion, on the droplet deformation and coalescence were systematically studied to provide theoretical basis for the efficient application of electric demulsification technology. According to the results, the higher the electric field intensity, root mean square(RMS) of electric field waveform and droplet size, the greater the deformability and coalescence ability of droplets are. The droplet deformation is independent of frequency under the high-frequency conditions, and the frequency has little effect on the coalescence rate of droplets. Meanwhile, the droplet deformation and coalescence rate can been improved by decreasing the continuous phase viscosity and oil-water interfacial tension. In addition, the microcosmic mechanism of droplet deformation and coalescence was also discussed. It is found that the maximum droplet deformation is in strong linear relationship with the electric Weber number in the case of small deformation, and the electric field intensity,droplet size and interfacial tension affect the coalescence efficiency of droplets by influencing the evolution of liquid bridge between droplets.

Oils, fats, and waxes, Gas industry
DOAJ Open Access 2022
High‐density genomic data reveal fine‐scale population structure and pronounced islands of adaptive divergence in lake whitefish (Coregonus clupeaformis) from Lake Michigan

Yue Shi, Jared J. Homola, Peter T. Euclide et al.

Abstract Understanding patterns of genetic structure and adaptive variation in natural populations is crucial for informing conservation and management. Past genetic research using 11 microsatellite loci identified six genetic stocks of lake whitefish (Coregonus clupeaformis) within Lake Michigan, USA. However, ambiguity in genetic stock assignments suggested those neutral microsatellite markers did not provide adequate power for delineating lake whitefish stocks in this system, prompting calls for a genomics approach to investigate stock structure. Here, we generated a dense genomic dataset to characterize population structure and investigate patterns of neutral and adaptive genetic diversity among lake whitefish populations in Lake Michigan. Using Rapture sequencing, we genotyped 829 individuals collected from 17 baseline populations at 197,588 SNP markers after quality filtering. Although the overall pattern of genetic structure was similar to the previous microsatellite study, our genomic data provided several novel insights. Our results indicated a large genetic break between the northwestern and eastern sides of Lake Michigan, and we found a much greater level of population structure on the eastern side compared to the northwestern side. Collectively, we observed five genomic islands of adaptive divergence on five different chromosomes. Each island displayed a different pattern of population structure, suggesting that combinations of genotypes at these adaptive regions are facilitating local adaptation to spatially heterogenous selection pressures. Additionally, we identified a large linkage disequilibrium block of ~8.5 Mb on chromosome 20 that is suggestive of a putative inversion but with a low frequency of the minor haplotype. Our study provides a comprehensive assessment of population structure and adaptive variation that can help inform the management of Lake Michigan's lake whitefish fishery and highlights the utility of incorporating adaptive loci into fisheries management.

DOAJ Open Access 2022
Ulysses Flyby in the Heliosphere: Comparison of the Solar Wind Model with Observational Data

Evgeniy V. Maiewski, Helmi V. Malova, Victor Yu. Popov et al.

A model capable of reproducing a set of solar wind parameters along the virtual spacecraft orbit out of an ecliptic plane has been developed. In the framework of a quasi-stationary axisymmetric self-consistent MHD model the spatial distributions of magnetic field and plasma characteristics at distances from 20 to 1200 Solar radii at almost all solar latitudes could be obtained and analyzed. This model takes into account the Sun’s magnetic field evolution during the solar cycle, when the dominant dipole magnetic field is replaced by the quadrupole one. Self-consistent solutions for solar wind characteristics were obtained, depending on the phase of the solar cycle. To verify the model, its results are compared with the observed characteristics of solar wind along the Ulysses trajectory during its flyby around the Sun from 1990 to 2009. It is shown that the results of numerical simulation are generally consistent with the observational data obtained by the Ulysses spacecraft. A comparison of the model and experimental data confirms that the model can adequately describe the solar wind parameters and can be used for heliospheric studies at different phases of the solar activity cycle, as well as in a wide range of latitudinal angles and distances to the Sun.

Elementary particle physics
DOAJ Open Access 2021
Dendritic Zn Deposition in Zinc‐Metal Batteries and Mitigation Strategies

Vahid Jabbari, Tara Foroozan, Reza Shahbazian-Yassar

As one of the most promising energy storage technologies, zinc (Zn)‐metal batteries (ZMBs) have attracted significant attention due to outstanding properties of Zn, including high energy density (820 mAh g−1/5855 mAh cm−3), abundance, low cost, low reactivity, multielectron redox capacity, compatibility with aqueous electrolytes, low equilibrium potential (−0.76 V vs SHE), stability, safety, and environmental benignity. Yet, the existence of some major issues such as surface‐originated parasitic reactions (e.g., corrosion and H2 evolution), formation of dead Zn, and oxide passivation leading to capacity loss in ZMBs are hindering their full potential applications. Addressing these challenges requires profound understanding of mechanism of Zn dendrites formation. Therefore, the aim of the current study is to assess some of the latest challenges and advancements concerning ZMBs, with an emphasis on origin and growth mechanism of Zn dendrites. Herein, it is demonstrated that the Zn electrodeposition does not follow a simple reaction/diffusion limited behavior, and other parameters such as surface energy and surface diffusion barrier play great roles on the morphology and microstructure of the deposited Zn. In addition, recent advances to mitigate Zn dendrite issues by applying modifications on the design of electrode, electrolyte, separator and interface are discussed.

Environmental technology. Sanitary engineering, Renewable energy sources
DOAJ Open Access 2020
Tympanojugular paragangliomas. Two case reports

Raluca GRIGORE, Anca I. CIRSTEA, Paula BEJENARU et al.

Introduction. Paragangliomas are benign tumours that arise from the paraganglionic system. The most frequently encountered symptoms of tympanojugular paragangliomas are pulsatile tinnitus and conductive hearing loss. High resolution computed tomography, with reconstruction in axial and coronal planes, is mandatory in every suspected case of tympanojugular paraganglioma. The treatment is guided by the classification of Fish. Cases presentation. We present two cases in whom the clinical manifestations and paraclinical investigations established the diagnosis of tympanojugular paraganglioma. Both surgery and postoperative evolution are described for each case. In most of these tumours, surgery remains the mainstay treatment. According to the preoperative plan of the first case, it was decided that the tumour can be resected safely, without compromising the cranial nerves. In the second case, the entire tumour was removed, but with the sacrifice of the inferior cranial nerve, caught in the tumour mass. Conclusions. These tumours have the tendency to involve multiple vital structures of the skull base. A detailed preoperative plan of treatment is required to maximize tumour resection, while minimizing morbidity of the great vessels and lower cranial nerves.

Medicine, Medicine (General)
DOAJ Open Access 2020
A new basal ornithopod dinosaur from the Lower Cretaceous of China

Yuqing Yang, Wenhao Wu, Paul-Emile Dieudonné et al.

A new basal ornithopod dinosaur, based on two nearly complete articulated skeletons, is reported from the Lujiatun Beds (Yixian Fm, Lower Cretaceous) of western Liaoning Province (China). Some of the diagnostic features of Changmiania liaoningensis nov. gen., nov. sp. are tentatively interpreted as adaptations to a fossorial behavior, including: fused premaxillae; nasal laterally expanded, overhanging the maxilla; shortened neck formed by only six cervical vertebrae; neural spines of the sacral vertebrae completely fused together, forming a craniocaudally-elongated continuous bar; fused scapulocoracoid with prominent scapular spine; and paired ilia symmetrically inclined dorsomedially, partially covering the sacrum in dorsal view. A phylogenetic analysis places Changmiania liaoningensis as the most basal ornithopod dinosaur described so far. It is tentatively hypothesized that both Changmiania liaoningensis specimens were suddenly entrapped in a collapsed underground burrow while they were resting, which would explain their perfect lifelike postures and the complete absence of weathering and scavenging traces. However, further behavioural inference remains problematic, because those specimens lack extensive sedimentological and taphonomic data, as it is also the case for most specimens collected in the Lujiatun Beds so far.

Medicine, Biology (General)
DOAJ Open Access 2018
Molecular Typing of ST239-MRSA-III From Diverse Geographic Locations and the Evolution of the SCCmec III Element During Its Intercontinental Spread

Stefan Monecke, Stefan Monecke, Stefan Monecke et al.

ST239-MRSA-III is probably the oldest truly pandemic MRSA strain, circulating in many countries since the 1970s. It is still frequently isolated in some parts of the world although it has been replaced by other MRSA strains in, e.g., most of Europe. Previous genotyping work (Harris et al., 2010; Castillo-Ramírez et al., 2012) suggested a split in geographically defined clades. In the present study, a collection of 184 ST239-MRSA-III isolates, mainly from countries not covered by the previous studies were characterized using two DNA microarrays (i) targeting an extensive range of typing markers, virulence and resistance genes and (ii) a SCCmec subtyping array. Thirty additional isolates underwent whole-genome sequencing (WGS) and, together with published WGS data for 215 ST239-MRSA-III isolates, were analyzed using in-silico analysis for comparison with the microarray data and with special regard to variation within SCCmec elements. This permitted the assignment of isolates and sequences to 39 different SCCmec III subtypes, and to three major and several minor clades. One clade, characterized by the integration of a transposon into nsaB and by the loss of fnbB and splE was detected among isolates from Turkey, Romania and other Eastern European countries, Russia, Pakistan, and (mainly Northern) China. Another clade, harboring sasX/sesI is widespread in South-East Asia including China/Hong Kong, and surprisingly also in Trinidad &amp; Tobago. A third, related, but sasX/sesI-negative clade occurs not only in Latin America but also in Russia and in the Middle East from where it apparently originated and from where it also was transferred to Ireland. Minor clades exist or existed in Western Europe and Greece, in Portugal, in Australia and New Zealand as well as in the Middle East. Isolates from countries where this strain is not epidemic (such as Germany) frequently are associated with foreign travel and/or hospitalization abroad. The wide dissemination of this strain and the fact that it was able to cause a hospital-borne pandemic that lasted nearly 50 years emphasizes the need for stringent infection prevention and control and admission screening.

DOAJ Open Access 2013
Metschnikowia Species Share a Pool of Diverse rRNA Genes Differing in Regions That Determine Hairpin-Loop Structures and Evolve by Reticulation.

Matthias Sipiczki, Walter P Pfliegler, Imre J Holb

Modern taxonomy of yeasts is mainly based on phylogenetic analysis of conserved DNA and protein sequences. By far the most frequently used sequences are those of the repeats of the chromosomal rDNA array. It is generally accepted that the rDNA repeats of a genome have identical sequences due to the phenomenon of sequence homogenisation and can thus be used for identification and barcoding of species. Here we show that the rDNA arrays of the type strains of Metschnikowia andauensis and M. fructicola are not homogenised. Both have arrays consisting of diverse repeats that differ from each other in the D1/D2 domains by up to 18 and 25 substitutions. The variable sites are concentrated in two regions that correspond to back-folding stretches of hairpin loops in the predicted secondary structure of the RNA molecules. The substitutions do not alter significantly the overall hairpin-loop structure due to wobble base pairing at sites of C-T transitions and compensatory mutations in the complementary strand of the hairpin stem. The phylogenetic and network analyses of the cloned sequences revealed that the repeats had not evolved in a vertical tree-like way but reticulation might have shaped the rDNA arrays of both strains. The neighbour-net analysis of all cloned sequences of the type strains and the database sequences of different strains further showed that these species share a continuous pool of diverse repeats that appear to evolve by reticulate evolution.

Medicine, Science
DOAJ Open Access 2012
Human developmental enhancers conserved between deuterostomes and protostomes.

Shoa L Clarke, Julia E VanderMeer, Aaron M Wenger et al.

The identification of homologies, whether morphological, molecular, or genetic, is fundamental to our understanding of common biological principles. Homologies bridging the great divide between deuterostomes and protostomes have served as the basis for current models of animal evolution and development. It is now appreciated that these two clades share a common developmental toolkit consisting of conserved transcription factors and signaling pathways. These patterning genes sometimes show common expression patterns and genetic interactions, suggesting the existence of similar or even conserved regulatory apparatus. However, previous studies have found no regulatory sequence conserved between deuterostomes and protostomes. Here we describe the first such enhancers, which we call bilaterian conserved regulatory elements (Bicores). Bicores show conservation of sequence and gene synteny. Sequence conservation of Bicores reflects conserved patterns of transcription factor binding sites. We predict that Bicores act as response elements to signaling pathways, and we show that Bicores are developmental enhancers that drive expression of transcriptional repressors in the vertebrate central nervous system. Although the small number of identified Bicores suggests extensive rewiring of cis-regulation between the protostome and deuterostome clades, additional Bicores may be revealed as our understanding of cis-regulatory logic and sample of bilaterian genomes continue to grow.

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