scholarly journals The Enigma of Interspecific Plasmodesmata: Insight From Parasitic Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Karsten Fischer ◽  
Lena Anna-Maria Lachner ◽  
Stian Olsen ◽  
Maria Mulisch ◽  
Kirsten Krause
Keyword(s):  
Host Plants ◽  
Large Range ◽  
Parasitic Plants ◽  
Individual Plant ◽  
Host System ◽  
Molecular Approaches ◽  
Open Questions ◽  
Technical Advances ◽  
Secondary Plasmodesmata ◽  
Insight Into

Parasitic plants live in intimate physical connection with other plants serving as their hosts. These host plants provide the inorganic and organic compounds that the parasites need for their propagation. The uptake of the macromolecular compounds happens through symplasmic connections in the form of plasmodesmata. In contrast to regular plasmodesmata, which connect genetically identical cells of an individual plant, the plasmodesmata that connect the cells of host and parasite join separate individuals belonging to different species and are therefore termed “interspecific”. The existence of such interspecific plasmodesmata was deduced either indirectly using molecular approaches or observed directly by ultrastructural analyses. Most of this evidence concerns shoot parasitic Cuscuta species and root parasitic Orobanchaceae, which can both infect a large range of phylogenetically distant hosts. The existence of an interspecific chimeric symplast is both striking and unique and, with exceptions being observed in closely related grafted plants, exist only in these parasitic relationships. Considering the recent technical advances and upcoming tools for analyzing parasitic plants, interspecific plasmodesmata in parasite/host connections are a promising system for studying secondary plasmodesmata. For open questions like how their formation is induced, how their positioning is controlled and if they are initiated by one or both bordering cells simultaneously, the parasite/host interface with two adjacent distinguishable genetic systems provides valuable advantages. We summarize here what is known about interspecific plasmodesmata between parasitic plants and their hosts and discuss the potential of the intriguing parasite/host system for deepening our insight into plasmodesmatal structure, function, and development.

scholarly journals Search for Resistant Genotypes to Cuscuta campestris Infection in Two Legume Species, Vicia sativa and Vicia ervilia

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 738
Author(s):  
Eva María Córdoba ◽  
Mónica Fernández-Aparicio ◽  
Clara Isabel González-Verdejo ◽  
Carmela López-Grau ◽  
María del Valle Muñoz-Muñoz ◽  
...  
Keyword(s):  
Agricultural Production ◽  
Host Plants ◽  
Resistance Breeding ◽  
Parasitic Plants ◽  
Vicia Sativa ◽  
Common Vetch ◽  
Germplasm Collections ◽  
Bitter Vetch ◽  
Cuscuta Campestris ◽  
Resistant Genotypes

The dodders (Cuscuta spp.) are parasitic plants that feed on the stems of their host plants. Cuscuta campestris is one of the most damaging parasitic plants for the worldwide agricultural production of broad-leaved crops. Its control is limited or non-existent, therefore resistance breeding is the best alternative both economically and environmentally. Common vetch (Vicia sativa) and bitter vetch (Vicia ervilia) are highly susceptible to C. campestris, but no resistant genotypes have been identified. Thus, the aim of this study was to identify in V. sativa and V.ervilia germplasm collections genotypes resistant to C. campestris infection for use in combating this parasitic plant. Three greenhouse screening were conducted to: (1) identify resistant responses in a collection of 154 accessions of bitter vetch and a collection of 135 accessions of common vetch genotypes against infection of C. campestris; (2) confirm the resistant response identified in common vetch accessions; and (3) characterize the effect of C. campestris infection on biomass of V. sativa resistant and susceptible accessions. Most common vetch and bitter vetch genotypes tested were susceptible to C. campestris. However, the V. sativa genotype Vs.1 exhibited high resistance. The resistant phenotype was characterized by a delay in the development of C. campestris posthaustorial growth and a darkening resembling a hypersensitive-like response at the penetration site. The resistant mechanism was effective in limiting the growth of C. campestris as the ratio of parasite/host shoot dry biomass was more significantly reduced than the rest of the accessions. To the best or our knowledge, this is the first identification of Cuscuta resistance in V. sativa genotypes.

scholarly journals Direct measurement of Coulomb-laser coupling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Doron Azoury ◽  
Michael Krüger ◽  
Barry D. Bruner ◽  
Olga Smirnova ◽  
Nirit Dudovich
Keyword(s):  
Coulomb Interaction ◽  
Time Domain ◽  
Coulomb Potential ◽  
Laser Field ◽  
Large Range ◽  
Extreme Ultraviolet ◽  
Strong Field ◽  
The Time Domain ◽  
First Time ◽  
Insight Into

AbstractThe Coulomb interaction between a photoelectron and its parent ion plays an important role in a large range of light-matter interactions. In this paper we obtain a direct insight into the Coulomb interaction and resolve, for the first time, the phase accumulated by the laser-driven electron as it interacts with the Coulomb potential. Applying extreme-ultraviolet interferometry enables us to resolve this phase with attosecond precision over a large energy range. Our findings identify a strong laser-Coulomb coupling, going beyond the standard recollision picture within the strong-field framework. Transformation of the results to the time domain reveals Coulomb-induced delays of the electrons along their trajectories, which vary by tens of attoseconds with the laser field intensity.

scholarly journals Conserved Mechanisms, Novel Anatomies: The Developmental Basis of Fin Evolution and the Origin of Limbs

Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 384
Author(s):  
Amanda N. Cass ◽  
Ashley Elias ◽  
Madeline L. Fudala ◽  
Benjamin D. Knick ◽  
Marcus C. Davis
Keyword(s):  
Gene Expression ◽  
Linear Connection ◽  
Expression Data ◽  
Evolutionary Novelty ◽  
Model Species ◽  
Animal Evolution ◽  
Molecular Approaches ◽  
Key Aspects ◽  
Insight Into ◽  
Appendage Patterning

The transformation of paired fins into tetrapod limbs is one of the most intensively scrutinized events in animal evolution. Early anatomical and embryological datasets identified distinctive morphological regions within the appendage and posed hypotheses about how the loss, gain, and transformation of these regions could explain the observed patterns of both extant and fossil appendage diversity. These hypotheses have been put to the test by our growing understanding of patterning mechanisms that regulate formation of the appendage axes, comparisons of gene expression data from an array of phylogenetically informative taxa, and increasingly sophisticated and elegant experiments leveraging the latest molecular approaches. Together, these data demonstrate the remarkable conservation of developmental mechanisms, even across phylogenetically and morphologically disparate taxa, as well as raising new questions about the way we view homology, evolutionary novelty, and the often non-linear connection between morphology and gene expression. In this review, we present historical hypotheses regarding paired fin evolution and limb origins, summarize key aspects of central appendage patterning mechanisms in model and non-model species, address how modern comparative developmental data interface with our understanding of appendage anatomy, and highlight new approaches that promise to provide new insight into these well-traveled questions.

scholarly journals A review of the endemic Hawaiian Drosophilidae and their host plants

Zootaxa ◽  
2008 ◽  
Vol 1728 (1) ◽  
pp. 1 ◽  
Author(s):  
KARL N. MAGNACCA ◽  
DAVID FOOTE ◽  
PATRICK M. O’GRADY
Keyword(s):  
Host Plant ◽  
Host Plants ◽  
Ecological Specialization ◽  
Primary Host ◽  
Evolutionarily Conserved ◽  
Rare And Endangered ◽  
Species Groups ◽  
Plant Families ◽  
Insight Into

The Hawaiian Drosophilidae is one of the best examples of rapid speciation in nature. Nearly 1,000 species of endemic drosophilids have evolved in situ in Hawaii since a single colonist arrived over 25 million years ago. A number of mechanisms, including ecological adaptation, sexual selection, and geographic isolation, have been proposed to explain the evolution of this hyperdiverse group of species. Here, we examine the known ecological associations of 326 species of endemic Hawaiian Drosophilidae in light of the phylogenetic relationships of these species. Our analysis suggests that the long-accepted belief of strict ecological specialization in this group does not hold for all taxa. While many species have a primary host plant family, females will also oviposit on non-preferred host plant taxa. Host shifting is fairly common in some groups, especially the grimshawi and modified mouthparts species groups of Drosophila, and the Scaptomyza subgenus Elmomyza. Associations with types of substrates (bark, leaves, flowers) are more evolutionarily conserved than associations with host plant families. These data not only give us insight into the role ecology has played in the evolution of this large group, but can help in making decisions about the management of rare and endangered host plants and the insects that rely upon them for survival.

Trematodes and snails: an intimate association

2004 ◽  
Vol 82 (2) ◽  
pp. 251-269 ◽  
Author(s):  
Anne E Lockyer ◽  
Catherine S Jones ◽  
Leslie R Noble ◽  
David Rollinson
Keyword(s):  
Evolutionary History ◽  
Intermediate Hosts ◽  
Molecular Approaches ◽  
Complex Interactions ◽  
Intimate Association ◽  
In Vitro Cell Cultures ◽  
Medical Burden ◽  
Insight Into ◽  
Trematode Parasites

Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail–trematode interactions. Laboratory-maintained snail–trematode systems and in vitro cell cultures are being used to investigate the molecular dialogue between host and parasite. These dynamic and finely balanced antagonistic relationships, in which parasites strongly influence the physiology of the host, are highly specific and may occasionally demonstrate co-speciation. We consider the mechanisms and responses deployed by trematodes and snails that result in compatibility or rejection of the parasite, and the macroevolutionary implications that they may effect. Although for gastropods the fossil record gives some insight into evolutionary history, elucidation of trematode evolution must rely largely upon molecular approaches, and for both, such techniques have provided fresh and often surprising evidence of their origins and dispersal over time. Co-evolution of snails and trematodes is becoming increasingly apparent at both cellular and population levels; the implications of which are only beginning to be understood for disease control. Untangling the complex interactions of trematodes and snails promise fresh opportunities for intervention to relieve the burden of parasitic disease.

Inhabitants of heritage: the dwellers of an Italian Renaissance palace and their problematic eviction in Ferrara, 1900–1940

Urban History ◽  
2020 ◽  
pp. 1-21
Author(s):  
Michele Nani
Keyword(s):  
Social Structure ◽  
Large Range ◽  
Italian Renaissance ◽  
Housing Problem ◽  
National Heritage ◽  
The Social ◽  
Nineteenth And Twentieth Centuries ◽  
Post War ◽  
Urban Demography ◽  
Insight Into

Abstract This article examines the eviction of tenants and squatters from a Renaissance palace in Ferrara, purchased by the Italian state in 1920. The case stands at the crossroads of three processes in European history between the nineteenth and twentieth centuries: the social and material ‘decadence’ of aristocratic residences, the birth of ‘national heritage’ and preservation policies and the explosion of the ‘housing problem’, following changes in urban demography and social structure. Considering a large range of sources, the article offers new insight into the conflict between different urban bureaucracies and inside them. It also explores the different forms of agency of working-class dwellers against the background of troubled post-war years followed by the advent of fascism.

Nitrogen Assimilation Enzyme Activities in Witchweed (Striga) in Hosts Presence and Absence

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 224-232 ◽  
Author(s):  
Imuetinyan Igbinnosa ◽  
Patrick A. Thalouarn
Keyword(s):  
Host Plant ◽  
Enzyme Activities ◽  
Host Plants ◽  
Nitrogen Assimilation ◽  
Reductase Activity ◽  
Growth Conditions ◽  
Plant Growth And Development ◽  
Continuous Darkness ◽  
N Assimilation ◽  
Insight Into

N fertilizers suppress witchweed plant growth and development, thus reducing the severity of parasite attack and increasing host yield simultaneously. However, the underlying physiological mode of N action occurring within the parasite cells remains largely unknown. This study aims at screening for the effects of N forms and different growth conditions on some N assimilation enzymes in witchweed seedlings grown aseptically without host plant, and in pots with host plants. Results show that supply of N in NH4+or urea forms resulted in 83 to 92% reduction in nitrate reductase activity (NRc), compared with control. Increasing NO3−concentrations from 0 mM to 100 mM, led to a corresponding increase in NRc in giant witchweed. NRc of giant witchweed seedlings grown under light and dark cycles were about 270 times higher than seedlings grown in continuous darkness. A combination of NH4+and NO3−, resulted in increased giant witchweed NRc, compared with NH4+or NO3−supplied singly. Highest shoot development and NRc was at NH4+and NO3−ratio 1:1, followed by ratios 1:3, 3:1, 0:1, and 1:0, respectively. Addition of N in soils resulted in increased NRc, followed by rapid deterioration and death of giant witchweed plants. NRc, GSc, and GDHc in witchweed, maize, cowpea, and tobacco were affected by diurnal fluctuations with higher enzyme activities occurring during the day than at night. Higher GSc than GDHc suggests that NH4+assimilation occurs mainly through the GS pathway in witchweed plants. NRc and GDHc were two and four times higher in giant witchweed grown in aseptic media without host plant, than that grown in potted soils with host plants. These findings provide insight into the physiological mode of N action and their implications on witchweed control.

Multiple and different genomic rearrangements of the rbcL gene are present in the parasitic orchid Neottia nidus-avis

Genome ◽  
2012 ◽  
Vol 55 (09) ◽  
pp. 629-637 ◽  
Author(s):  
Donata Cafasso ◽  
Gianni Chinali
Keyword(s):  
Plastid Genome ◽  
Photosynthetic Capacity ◽  
Parasitic Plants ◽  
Flowering Plants ◽  
Genomic Rearrangements ◽  
Rbcl Gene ◽  
Individual Plant ◽  
Fixed Carbon ◽  
Photosynthetic Genes ◽  
Rbcl Sequences

In parasitic plants that have lost most, if not all, of their photosynthetic genes, the genome of their plastids has also undergone a dramatic reduction. For example, photosynthetic genes, such as rbcL, frequently become pseudogenes, in which large portions of the gene have been found to be deleted. Orchids are flowering plants with several parasitic lineages. This is consistent with the observation that parasitic orchids can invade pre-existing mutualistic associations between ectomycorrhizal trees and fungi to obtain fixed carbon and nutrients. In addition, some parasitic species are devoid of chlorophyll, and consequently, have lost their photosynthetic capacity. Here, the organization of the plastid genome of the parasitic orchid Neottia nidus-avis (L.) Rich. was investigated using sequencing and hybridization experiments. In particular, genomic rearrangements in the rbcL region of this parasitic orchid were analyzed. At least three distinct rbcL sequences were found to be present as pseudogenes and were likely located in the plastid genome. Based on these results, it is hypothesized that N. nidus-avis contains different plastomes, each with a different pseudogene, and these can exist within the same individual plant.

scholarly journals The history of neurosurgery and its relation to the development and refinement of the frontotemporal craniotomy

2014 ◽  
Vol 36 (4) ◽  
pp. E12 ◽  
Author(s):  
D. Ryan Ormond ◽  
Costas G. Hadjipanayis
Keyword(s):  
19Th Century ◽  
Neurosurgical Procedures ◽  
Late 19Th Century ◽  
History Of Neurosurgery ◽  
Technical Advances ◽  
History Of ◽  
Cerebral Localization ◽  
Great Odds ◽  
Insight Into ◽  
Over Time

The history of neurosurgery is filled with descriptions of brave surgeons performing surgery against great odds in an attempt to improve outcomes in their patients. In the distant past, most neurosurgical procedures were limited to trephination, and this was sometimes performed for unclear reasons. Beginning in the Renaissance and accelerating through the middle and late 19th century, a greater understanding of cerebral localization, antisepsis, anesthesia, and hemostasis led to an era of great expansion in neurosurgical approaches and techniques. During this process, frontotemporal approaches were also developed and refined over time. Progress often depended on the technical advances of scientists coupled with the innovative ideas and courage of pioneering surgeons. A better understanding of this history provides insight into where we originated as a specialty and in what directions we may go in the future. This review considers the historical events enabling the development of neurosurgery as a specialty, and how this relates to the development of frontotemporal approaches.

Critical examination of growth rate for magnesium oxide (MgO) thin films deposited by molecular beam epitaxy with a molecular oxygen flux

2010 ◽  
Vol 25 (4) ◽  
pp. 670-679 ◽  
Author(s):  
Mark D. Losego ◽  
H. Spalding Craft ◽  
Elizabeth A. Paisley ◽  
Seiji Mita ◽  
Ramon Collazo ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Molecular Beam ◽  
Quartz Crystal ◽  
Large Range ◽  
Flux Ratio ◽  
Critical Examination ◽  
Molecular Scattering ◽  
Molecular Beam Deposition ◽  
Insight Into ◽  
Beam Deposition

The authors report a study of molecular beam deposition of MgO films on amorphous SiO2 and (0001) GaN surfaces over a large range of temperatures (25–400 °C) and molecular oxygen growth pressures (10−7–10−4 Torr). This study provides insight into the growth behavior of an oxide with volatile metal constituents. Unlike other materials containing volatile constituents (e.g., GaAs, PbTiO3), all components of MgO become volatile at normal epitaxial growth temperatures (≥250 °C). Consequently, defining which species is the adsorption controller becomes ambiguous. Different growth regimes are delineated by the critical substrate temperature for Mg re-evaporation and the Mg:O flux ratio. These regimes have impact on phase purity, quartz crystal microbalance calibration, and film microstructure. The universal decay in deposition rate above growth 10−5 Torr O2 is also considered. By introducing a third flux of inert argon gas, rate reduction is attributed to increased molecular scattering and not oxidation of the metal source.

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