Structural changes in the antennapedia complex of Drosophila pseudoobscura.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 319-330
Author(s):  
F M Randazzo ◽  
M A Seeger ◽  
C A Huss ◽  
M A Sweeney ◽  
J K Cecil ◽  
...  
Keyword(s):  
Structural Changes ◽  
Genetic Regulation ◽  
Drosophila Pseudoobscura ◽  
Evolutionary Divergence ◽  
Closely Related Species ◽  
Substantial Impact ◽  
Evolutionary Changes ◽  
Gene Complexes ◽  
Deformed Gene ◽  
Insight Into

Abstract The discovery of the striking positional conservation between the Antennapedia and Bithorax homeotic gene complexes (ANT-C and BX-C) in Drosophila melanogaster and the murine Hox and human HOX clusters has had a substantial impact on our understanding of the evolution of development and its genetic regulation. Structural differences do exist among the mammalian Hox complexes and the ANT-C in D. melanogaster. To gain further insight into the evolutionary changes among these complexes, the ANT-C was cloned in the closely related species, Drosophila pseudoobscura. The overall structure of the ANT-C in D. pseudoobscura is highly similar to its D. melanogaster counterpart; however, two differences in the organization of the ANT-C have been identified. First, the z2 gene, a member of the ANT-C in D. melanogaster, is not present in the D. pseudoobscura ANT-C and is possibly absent from the D. pseudoobscura genome. Second, the orientation of the Deformed gene is inverted in D. pseudoobscura, providing it with a 5' to 3' direction of transcription identical to the remaining ANT-C homeobox genes with the exception of fushi tarazu. These differences demonstrate that subtle changes can occur in ANT-C structure during relatively short periods of evolutionary divergence, although the fundamental organization of the complex is conserved. These observations and others suggest that the complex is not absolutely rigid but that selective pressures have maintained this organization of genes for some functional reason that remains elusive.

Global insight into microwave stoneware firing: Macro and micro structural changes

2021 ◽  
Author(s):  
T. Santos ◽  
C.S.F. Gomes ◽  
L. Hennetier ◽  
V.A.F. Costa ◽  
L.C. Costa
Keyword(s):  
Structural Changes ◽  
Insight Into

Gastric Brooding - a New Form in a Recently Discovered Australian Frog of the Genus Rheobatrachus

1986 ◽  
Vol 34 (2) ◽  
pp. 205 ◽  
Author(s):  
ASY Leong ◽  
MJ Tyler ◽  
DJC Shearman
Keyword(s):  
Structural Changes ◽  
Nuclear Material ◽  
Gastric Epithelium ◽  
Brooding Female ◽  
Apoptotic Bodies ◽  
Animal Kingdom ◽  
Closely Related Species ◽  
Eosinophilic Cytoplasm ◽  
Acid Secreting ◽  
New Form

The phenomenon of gastric brooding and oral birth displayed by the Australian frog Rheobatrachus silus has not previously been observed in the Animal Kingdom. This report describes another example of gastric brooding in a recently discovered, closely related species, Rheobatrachus vitellinus. The stomach of a female R. vitellinus that had given birth to 22 froglets revealed morphologic changes which were quite different to those described in R. silus. Unlike the atrophy of the mucosa and acid-secreting oxyntic cells in the latter species, there was no evidence of major structural changes in the brooding stomach of R. vitellinus. Furthermore, no differences were observed in the light microscopic appearances of the stomach in the brooding female and that from a non-brooding female and male R. vitellinus. A striking finding not observed in the non-brooding stomachs of R. vitellinus nor in R. silus was the presence of widespread and numerous apoptotic bodies in the gastric epithelium. The apoptotic bodies were recognized as phagocytosed fragments of eosinophilic cytoplasm and pyknotic nuclear material. Ultrastructurally, well preserved organelles were observed in the phagocytosed fragments. This diffuse deletion of cells and the striking absence of major structural changes in the brooding stomach may indicate a dichotomy in the evolution of this bizarre and unique reproductive habit.

scholarly journals Insight into surface and structural changes of montmorillonite and organomontmorillonites loaded with Ag

2019 ◽  
Vol 22 (2-3) ◽  
pp. 142-153 ◽  
Author(s):  
Alejandra M. Fernández Solarte ◽  
Jhonny Villarroel-Rocha ◽  
César Fernández Morantes ◽  
Maria L. Montes ◽  
Karim Sapag ◽  
...  
Keyword(s):  
Structural Changes ◽  
Insight Into

scholarly journals Bichir external gills arise via heterochronic shift that accelerates hyoid arch development

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jan Stundl ◽  
Anna Pospisilova ◽  
David Jandzik ◽  
Peter Fabian ◽  
Barbora Dobiasova ◽  
...  
Keyword(s):  
Pharyngeal Arch ◽  
Developmental Sequence ◽  
Free Living ◽  
Pharyngeal Arches ◽  
Hyoid Arch ◽  
Early Appearance ◽  
Evolutionary Changes ◽  
Insight Into ◽  
Living Group ◽  
Early Larvae

In most vertebrates, pharyngeal arches form in a stereotypic anterior-to-posterior progression. To gain insight into the mechanisms underlying evolutionary changes in pharyngeal arch development, here we investigate embryos and larvae of bichirs. Bichirs represent the earliest diverged living group of ray-finned fishes, and possess intriguing traits otherwise typical for lobe-finned fishes such as ventral paired lungs and larval external gills. In bichir embryos, we find that the anteroposterior way of formation of cranial segments is modified by the unique acceleration of the entire hyoid arch segment, with earlier and orchestrated development of the endodermal, mesodermal, and neural crest tissues. This major heterochronic shift in the anteroposterior developmental sequence enables early appearance of the external gills that represent key breathing organs of bichir free-living embryos and early larvae. Bichirs thus stay as unique models for understanding developmental mechanisms facilitating increased breathing capacity.

scholarly journals Population genetic analysis and evidence of inter-specific introgression in Helichrysum armenium and H. rubicundum (Asteraceae)

Genetika ◽  
2015 ◽  
Vol 47 (2) ◽  
pp. 451-468 ◽  
Author(s):  
Malahat Taban ◽  
Masoud Sheidai ◽  
Zahra Noormohammadi ◽  
Narjes Azizi ◽  
Somayeh Ghasemzadeh-Baraki ◽  
...  
Keyword(s):  
Population Genetic ◽  
Structural Changes ◽  
Genetic Difference ◽  
Genetic Admixture ◽  
Specific Gene ◽  
Population Genetic Study ◽  
Population Genetic Analysis ◽  
Closely Related Species ◽  
Geographical Populations ◽  
Genetic Stratification

Helichrysum armenium and H. rubicundum are two medicinally important plants of Iran that are distributed in various regions of the country. They are extensively used by locals as medicinal plants and a great negative selection pressure is applied on them. Therefore, due to importance of these plant species, we performed a population genetic study in both species. For this study, we used 66 randomly collected plants from 24 geographical populations of Helichrysum armenium and H. rubicundu. These species had areas of overlap and contact and we found some intermediate plants that were included in our study too. UPGMA and MDS analyses revealed morphological separation of these closely related species and placed intermediate plants in an intermediate position. ISSR analysis revealed inter-population genetic diversity and K-Means clustering and STRUCTURE analyses revealed populations. Genetic stratification in both species. Genetic difference of the studied populations was not correlated to geographical distance. Triangle plot of Bayesian analysis and NeighborNet plot showed inter-specific gene flow. The studied populations showed plants with 2n = 2x = 14 and 2n = 4x = 28 chromosomes and differed significantly in their meiotic behavior. Therefore, a combination of genetic stratification, and genetic admixture as well as polyploidy and chromosomes structural changes, have played rule in Helichrysum diversification.

Evolutionary conservatism will limit responses to climate change in the tropics

2021 ◽  
Vol 17 (10) ◽  
Author(s):  
Ethan B. Linck ◽  
Benjamin G. Freeman ◽  
C. Daniel Cadena ◽  
Cameron K. Ghalambor
Keyword(s):  
Thermal Tolerance ◽  
Species Turnover ◽  
Tropical Species ◽  
Evolutionary Divergence ◽  
Closely Related Species ◽  
Tropical Mountains ◽  
Low Latitudes ◽  
Parapatric Speciation ◽  
The Tropics

Rapid species turnover in tropical mountains has fascinated biologists for centuries. A popular explanation for this heightened beta diversity is that climatic stability at low latitudes promotes the evolution of narrow thermal tolerance ranges, leading to local adaptation, evolutionary divergence and parapatric speciation along elevational gradients. However, an emerging consensus from research spanning phylogenetics, biogeography and behavioural ecology is that this process rarely, if ever, occurs. Instead, closely related species typically occupy a similar elevational niche, while species with divergent elevational niches tend to be more distantly related. These results suggest populations have responded to past environmental change not by adapting and diverging in place, but instead by shifting their distributions to tightly track climate over time. We argue that tropical species are likely to respond similarly to ongoing and future climate warming, an inference supported by evidence from recent range shifts. In the absence of widespread in situ adaptation to new climate regimes by tropical taxa, conservation planning should prioritize protecting large swaths of habitat to facilitate movement.

scholarly journals Overview and Insights into Carbapenem Allergy

Pharmacy ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 110 ◽  
Author(s):  
Yuman Lee ◽  
Nicole Bradley
Keyword(s):  
Case Reports ◽  
Review Article ◽  
Limited Data ◽  
Substantial Impact ◽  
Cross Sensitivity ◽  
Search Terms ◽  
Incidence Risk ◽  
Pubmed Search ◽  
The Individual ◽  
Insight Into

Understanding antibiotic allergies and the risk of cross-sensitivity between and within antibiotic classes can have a substantial impact on patient care. The purpose of this review article is to provide insight into carbapenem allergies, describing the overall incidence, risk factors, and in-class cross-sensitivity. A PubMed search was conducted using the following search terms: carbapenem, allergy, cross-sensitivity, incidence, imipenem/cilastatin, meropenem, ertapenem, and doripenem. Article bibliographies and relevant drug monographs were also reviewed. The overall reported incidence of carbapenem allergy is 0.3%–3.7%. Risk of cross-sensitivity between penicillins and carbapenems is less than 1% in patients with a positive penicillin skin test. Data on cross-sensitivity between cephalosporins and carbapenems are limited; however, the risk appears to also be low. No clinical studies have described cross-sensitivity between the carbapenem agents thus far. The limited data available from case reports demonstrates a lack of cross-sensitivity between the individual carbapenems, suggesting that an alternative carbapenem may cautiously be used in patients with a reported carbapenem allergy.

scholarly journals Tracing the Lineage of Two Traits Associated with the Coat Protein of the Tombusviridae: Silencing Suppression and HR Elicitation in Nicotiana Species

Viruses ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 588 ◽  
Author(s):  
Mustafa Adhab ◽  
Carlos Angel ◽  
Andres Rodriguez ◽  
Mohammad Fereidouni ◽  
Lóránt Király ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Structural Changes ◽  
Coat Proteins ◽  
Silencing Suppressor ◽  
Suppressor Activity ◽  
Nicotiana Species ◽  
Pathogen Effector ◽  
The Family ◽  
Silencing Suppression ◽  
Insight Into

In this paper we have characterized the lineage of two traits associated with the coat proteins (CPs) of the tombusvirids: Silencing suppression and HR elicitation in Nicotiana species. We considered that the tombusvirid CPs might collectively be considered an effector, with the CP of each CP-encoding species comprising a structural variant within the family. Thus, a phylogenetic analysis of the CP could provide insight into the evolution of a pathogen effector. The phylogeny of the CP of tombusvirids indicated that CP representatives of the family could be divided into four clades. In two separate clades the CP triggered a hypersensitive response (HR) in Nicotiana species of section Alatae but did not have silencing suppressor activity. In a third clade the CP had a silencing suppressor activity but did not have the capacity to trigger HR in Nicotiana species. In the fourth clade, the CP did not carry either function. Our analysis illustrates how structural changes that likely occurred in the CP effector of progenitors of the current genera led to either silencing suppressor activity, HR elicitation in select Nicotiana species, or neither trait.

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