Can fruit ontogenetic features prove to be an important tool in the circumscription of Psychotrieae alliance?

2021 ◽  
Author(s):  
Anderson F. Santos ◽  
Amanda A. O. do Carmo ◽  
Vanessa C. Harthman ◽  
Mariza B. Romagnolo ◽  
Luiz A. Souza
Keyword(s):  
Structural Features ◽  
State Parks ◽  
Inferior Ovary ◽  
Brazilian State ◽  
Long Time

The Rubiaceae tribe Psychotrieae sensu lato and its two largest genera, Psychotria L. and Palicourea Aubl., have been considered taxonomically controversial for a long time. We aimed to identify structural features of the ontogeny of the fruits and seeds with taxonomic potential for the tribe by using species of these two genera, and Rudgea jasminoides (Cham.) Müll.Arg. The samples were obtained from a herbarium and from Brazilian state parks, and sectioned by using a rotation microtome. The fruits were found to be derived from an inferior ovary, and were characterised by a fleshy mesocarp and sclerenchymatic sinuate pyrene. The seeds were pachychalazal and arillate. The fruit was classified as a pomaceous drupoid nuculanium. The investigation showed the utility of some fruit features to discriminate species. Our study also showed that ontogenetic features of fruits and seeds are very homogeneous in Palicourea and Psychotria, which supports the inclusion of both genera in the tribe Psychotrieae.

scholarly journals A record of deglaciation-related shifting of the proximal zone of a sandur — a case study from the Gwda sandur, NW Poland (MIS 2)

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mateusz Mleczak ◽  
Małgorzata Pisarska-Jamroży
Keyword(s):  
Structural Features ◽  
Complex Problem ◽  
Coarse Grained ◽  
Fine Grained ◽  
Depositional Processes ◽  
Long Time ◽  
Sedimentary Succession ◽  
Late Weichselian ◽  
Proximal Zone ◽  
Nw Poland

AbstractThe study analyses a 7.5-m-thick sedimentary succession deposited in the largest sandur (the Gwda sandur, a glacial outwash plain) in NW Poland, during the late Weichselian (MIS 2). Although the study site is located in the distal zone of the sandur, its sedimentological features and palaeohydrological parameters reflect the presence of an energetic, powerful environment typical of the proximal zone. Three sedimentary units were recognized in the studied sedimentary succession: (1) lower unit — fine-grained sands with ripple cross-lamination and horizontal lamination; (2) middle unit — gravelly coarse-grained sands and sandy gravels with planar cross-stratification; and, (3) upper unit — sands and gravelly sands with trough cross-stratification. Although the age of deposition of the sandur is accepted to be convergent with that of end-moraines of the same phase, the sediments in the distal zone of the Gwda sandur correlate with an earlier glaciation phase/subphase. Our findings hint at a complex problem: large sandurs such as the Gwda sandur were probably deposited over a long time, and their successions might record the textural and structural features of the proximal subenvironment, even in their distal parts due to deglaciation-related shifting of the proximal zone of a sandur. This paper presents a new approach to analysing the depositional processes in large sandurs, shows a new light on glaciofluvial water supply dynamics of distal parts of sandurs, and may solve several fundamental problems related to the sandur deposition.

scholarly journals Autophagy and evasion of immune system by SARS-CoV-2. Structural features of the Non-structural protein 6 from Wild Type and Omicron viral strains interacting with a model lipid bilayer.

2022 ◽  
Author(s):  
Emmanuelle Bignon ◽  
Marco Marazzi ◽  
Stephanie Grandemange ◽  
Antonio Monari
Keyword(s):  
Lipid Bilayer ◽  
Defense Mechanisms ◽  
Lipid Membrane ◽  
Structural Features ◽  
Endoplasmic Reticulum Membrane ◽  
Interaction Patterns ◽  
Structural Protein ◽  
Dynamic Simulations ◽  
Long Time ◽  
Cellular Machinery

The viral cycle of SARS-CoV-2 is based on a complex interplay with the cellular machinery, which is mediated by specific proteins eluding or hijacking the cellular defense mechanisms. Among the complex pathways called by the viral infection autophagy is particularly crucial and is strongly influenced by the action of the non-structural protein 6 (Nsp6) interacting with the endoplasmic reticulum membrane. Importantly, differently from other non-structural proteins Nsp6 is mutated in the recently emerged Omicron variant, suggesting a possible different role of autophagy. In this contribution we explore, for the first time, the structural property of Nsp6 thanks to long-time scale molecular dynamic simulations and machine learning analysis, identifying the interaction patterns with the lipid membrane. We also show how the mutation brought by the Omicron variant may indeed modify some of the specific interactions, and more particularly help anchoring the viral protein to the lipid bilayer interface.

Structural studies of the cell wall polysaccharide of Nocardia asteroides R 399

1985 ◽  
Vol 31 (11) ◽  
pp. 1011-1018 ◽  
Author(s):  
Annie Voiland ◽  
Georges Michel
Keyword(s):  
Cell Wall ◽  
Bacterial Species ◽  
Structural Features ◽  
Nocardia Asteroides ◽  
Cell Wall Polysaccharide ◽  
Cell Wall Polysaccharides ◽  
Phosphodiester Bond ◽  
Long Time ◽  
Carbohydrate Polymer

As with other bacteria belonging to the corynebacteria, mycobacteria, and nocardia group, Nocardia possess in their cell walls a neutral polysaccharide. Structural analysis of the cell wall polysaccharide of Nocardia asteroides R 399 was undertaken. The carbohydrate polymer contained D-arabinose and D-galactose as in mycobacteria. Besides these two carbohydrates we pointed out the occurrence of two additional components: D-glucose and a polyol. This polyol, because of its small amount and its uneasy detection, had been for a long time ignored. It has been proven to be the 6-deoxy-D-altritol or 1-deoxy-D-talitol. The polymer consists of a main strand composed of →5 Araf 1→ and →4Galp1→ or→5Galf1→; oligoarabinosyl side chains were localized on C3 of an arabinosyl residue. Other shorter ramifications also occur on some galactosyl units. A characterization of the linkage between polysaccharide and peptidoglycan inside the cell wall has also been carried out. The two polymers are joined by a phosphodiester bond which involves 6-deoxyaltritol. As some corynebacteria previously analyzed were also shown to contain mannose (and sometimes glucose), we can conclude that the main skeleton of cell wall polysaccharides of the corynebacteria, mycobacteria, and nocardia group of bacteria is an arabinogalactan; however, individual structural features of the polysaccharide are varying according to the bacterial species. These results might be connected with variations that were observed in immunological analysis.

scholarly journals Deep clustering of protein folding simulations

2018 ◽  
Author(s):  
Debsindhu Bhowmik ◽  
Shang Gao ◽  
Michael T Young ◽  
Arvind Ramanathan
Keyword(s):  
Protein Folding ◽  
Structural Features ◽  
Conformational Substates ◽  
Learning Techniques ◽  
Latent Features ◽  
Model Protein ◽  
Long Time ◽  
Biomolecular Simulations ◽  
Folding Simulations ◽  
Low Dimensional

AbstractWe examine the problem of clustering biomolecular simulations using deep learning techniques. Since biomolecular simulation datasets are inherently high dimensional, it is often necessary to build low dimensional representations that can be used to extract quantitative insights into the atomistic mechanisms that underlie complex biological processes. In this paper, we use a convolutional variational autoencoder (CVAE) to learn low dimensional, biophysically relevant latent features from long time-scale protein folding simulations in an unsupervised manner. We demonstrate our approach on three model protein folding systems, namely the Fs-peptide (14μs aggregate sampling), villin head piece (single trajectory of 125μs) and the mixedβ-β-α(BBA) protein (223 + 102μs sampling across two independent trajectories). In these systems, we show that the CVAE latent features learned correspond to distinct conformational substates along the protein folding pathways. The CVAE model predicts nearly 89% of all contacts within the folding trajectories correctly, while being able to extract folded, unfolded and potentially misfolded states in an unsupervised manner. Further, the CVAE model can be used to learn latent features of protein folding that can be applied to other independent trajectories, making it particularly attractive for identifying intrinsic features that correspond to conformational substates that share similar structural features. Together, we show that the CVAE model can quantitatively describe complex biophysical processes such as protein folding.

scholarly journals Сінтаксічныя канструкцыі тыпу “на + вінавальны склон” і “на + месны склон” ў беларускіх паўночна‑заходніх народных гаворках і яе пагранічча

2015 ◽  
Vol 37 ◽  
pp. 323-331
Author(s):  
Юлія [IUliia] Хвіланчук [Khvilanchuk]
Keyword(s):  
Structural Features ◽  
Standard Variety ◽  
The West ◽  
North West ◽  
High Productivity ◽  
Exact Time ◽  
Need Analysis ◽  
Usage Patterns ◽  
Long Time ◽  
Geographical Expansion

Prepositional constructions with ‘na’ in folk dialects of north-west BelarusThis article is a study of such prepositional constructions as aslepnuts na vochy, hvarets na astsu, azlabіtstsa na sina, graz na dudtsy, ehats na kanі in folk dialects of north-west Belarus. These constructions have received too little attention in the research on the standard variety of Belorussian and a few issues still need analysis: the usage patterns of the structure and its relations with other dialects. In this paper, we discuss the structural features, the geographical expansion and the prescriptive status of the construction. Our study revealed that the constructions can express different mea­nings, and they modify the meaning of the verb. The analysed structure exhibits high productivity in the dialects of north-west Belarus. We believe that all prepositional constructions of this kind were derived from non-prepositional constructions; the exact time of such shift is difficult to determine, since the two kinds of constructions have existed in parallel for a long time. The prepositional construction ehats na kanі is normative in modern Belorussian and Russian. In the west of Belarus, people also use the prepositionless variant of the construction: ehats kanem. Синтаксические конструкции типа «на + винительный падеж» и «на + предложный падеж» в белорусских северо-западных говорах и их пограничьяЦелью статьи является исследование синтаксических конструкций типа “на + винительный” и “на + предложный” в белорусских северо-западных народных говорах и их пограничья. Объектом исследования послужили словосочетания с предлогом на, которые выражают объектные отношения. Особенности применения таких конструкций в говорах белорусского языка со стороны территории их расширения, внутри- и мeждиалектных отношений до сих пор составляют научную проблему. Они недостаточно исследованы в национальной диалектологии и поэтому требуют детального анализа, хотя вопросы изучения синтаксических конструкций не являются новыми для славянской диалектологии в целом. В данной статье мы попытались охарактеризовать синтаксические отношения словосочетаний типа “на + винительный” и “на + предложный” структурные особенности таких конструкций, территорию их расширения, нормативный статус. В результате исследования выявилось, что синтаксические конструкции с объектными отношениями могут выражать различные значения. В качестве главного кампонента таких словосочетаний обычно выступают различные по значению глаголы. Конструкции типа “на + винительный” и “на + предложный” достаточно продуктивны в белорусских северо-западных народных говорах и пограничья. Параллельно с предложными словосочетаниями в говорах могут употребляться и беспредложные синтаксические конструкции. Есть мнение, что все предложные конструкции возникли на базе беспредложных. Когда состоялся процесс их разграничения на сегодняшний момент сказать трудно, так как предложные и беспредложные словосочетания долгое время применялись параллельно. Так, предложная конструкция “ехаць на кані” является нормативной в современном белорусском и русском языках. Функционирование же беспредложной синтаксической конструкции “ехаць канём” на западе Беларуси поддерживается за счет соседних языков – польского и литовского, где такие словосочетания считаются нормативными.

EFFECTS OF ADAPTIVE SOCIAL NETWORKS ON THE ROBUSTNESS OF EVOLUTIONARY ALGORITHMS

2011 ◽  
Vol 20 (05) ◽  
pp. 783-817 ◽  
Author(s):  
JAMES M. WHITACRE ◽  
RUHUL A. SARKER ◽  
Q. TUAN PHAM
Keyword(s):  
Evolutionary Algorithm ◽  
Biological Networks ◽  
Fitness Landscape ◽  
Structural Features ◽  
New Paradigm ◽  
Design Problems ◽  
Search Heuristics ◽  
Engineering Design Problems ◽  
Long Time ◽  
System Robustness

Biological networks are structurally adaptive and take on non-random topological properties that influence system robustness. Studies are only beginning to reveal how these structural features emerge, however the influence of component fitness and community cohesion (modularity) have attracted interest from the scientific community. In this study, we apply these concepts to an evolutionary algorithm and allow its population to self-organize using information that the population receives as it moves over a fitness landscape. More precisely, we employ fitness and clustering based topological operators for guiding network structural dynamics, which in turn are guided by population changes taking place over evolutionary time. To investigate the effect on evolution, experiments are conducted on six engineering design problems and six artificial test functions and compared against cellular genetic algorithms and panmictic evolutionary algorithm designs. Our results suggest that a self-organizing topology evolutionary algorithm can exhibit robust search behavior with strong performance observed over short and long time scales. More generally, the coevolution between a population and its topology may constitute a promising new paradigm for designing adaptive search heuristics.

scholarly journals Evaluation of the possibility of manifestation of deformations from the position of disturbance of the massif (using the Kamagan field as an example)

2020 ◽  
pp. 173-182
Author(s):  
Oksana Sergeevna KOLESATOVA ◽  
◽  
Elena Aleksandrovna GORBATOVA ◽  
◽  
Keyword(s):  
Structural Features ◽  
Open Pit ◽  
Main Task ◽  
Mining Operations ◽  
Edge Zone ◽  
Stability Of Slopes ◽  
Fracture Systems ◽  
Prediction And Prevention ◽  
Long Time ◽  
The Stability

Introduction. The main task in the development of mineral deposits by open and underground methods is to ensure the safety of mining operations. As a result of long-time standing of the pit walls in the near edge zone massif, changes in natural stresses can occur, which lead to deformations. Prediction and prevention of deformation processes of the near-rock massif largely depend on reliable information about its structural features, including the structure of the massif and the degree of its disturbance. Purpose of research is to assess the possibility of manifestation of deformations from the position of disturbance of the massif. Methods of research. When assessing the possibility of deformation manifestation, a set of methods was used, including: full-scale measurements of fracturing; methods of mathematical statistics using the Stereonet program for processing measurement results; analysis of the spatial position of cracks relative to the direction of strike of the slopes and sides of the open pit with the identification of the most dangerous ones; kinematic analysis, allowing to determine potential types of loss of stability from the position of disturbance of the massif. Result of research. In the southeastern, northern and western sides of the Kamagan open pit, 41 fracture systems have been identified; the prevailing systems are northwestern dip systems at angles of 50 ° –85 °; south-east - at an angle of 50 ° and south-west - at an angle of 50 °. For example, for the northern side (Ap = 90 °; n = 60 °), it was found that potential types of destabilization are: wedge formed by systems of cracks with spatial characteristics Ap = 65 °; n = 45 ° and Apr = 150 °; n = 90 °, and planar sliding formed by systems of cracks with the parameters Ap = 90 °; n = 55 ° and Apr = 100 °; n = 42 °. Conclusions. Studies have proven the need to study and identify weakening surfaces in the process of mining and determine the parameters of their occurrence in order to assess the possibility of deformations and further assess the stability of slopes.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Sign in / Sign up

Export Citation Format

Share Document