scholarly journals The Effect of Chromosome Structure upon Meiotic Homologous and Homoeologous Recombinations in Triticeae

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 552 ◽  
Author(s):  
Tomás Naranjo
Keyword(s):  
Meiotic Recombination ◽  
Structural Changes ◽  
High Capacity ◽  
Genetic Studies ◽  
Negative Effect ◽  
Chromosomal Architecture ◽  
Homoeologous Relationships ◽  
Agronomical Traits ◽  
Interspecific Recombination ◽  
Intercalary Region

The tribe Triticeae contains about 500 diploid and polyploid taxa, among which are important crops, such as wheat, barley and rye. The phylogenetic relationships, genome compo-sition and chromosomal architecture, were already reported in the pioneer genetic studies on these species, given their implications in breeding-related programs. Hexaploid wheat, driven by its high capacity to develop cytogenetic stocks, has always been at the forefront of these studies. Cytogenetic stocks have been widely used in the identification of homoeologous relationships between the chromosomes of wheat and related species, which has provided valuable information on genome evolution with implications in the transfer of useful agronomical traits into crops. Meiotic recombination is non-randomly distributed in the Triticeae species, and crossovers are formed in the distal half of the chromosomes. Also of interest for crops improvement is the possibility of being able to modulate the intraspecific and interspecific recombination landscape to increase its frequency in crossover-poor regions. Structural changes may help in this task. In fact, chromosome truncation increases the recombination frequency in the adjacent intercalary region. However, structural changes also have a negative effect upon recombination. Gross chromosome rearrangements produced in the evolution usually suppress meiotic recombination between non-syntenic homoeologs. Thus, the chromosome structural organization of related genomes is of great interest in designing strategies of the introgression of useful genes into crops.

scholarly journals Genetic Studies of mei-P26 Reveal a Link Between the Processes That Control Germ Cell Proliferation in Both Sexes and Those That Control Meiotic Exchange in Drosophila

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1757-1772 ◽  
Author(s):  
Scott L Page ◽  
Kim S McKim ◽  
Benjamin Deneen ◽  
Tajia L Van Hook ◽  
R Scott Hawley
Keyword(s):  
Meiotic Recombination ◽  
Double Mutant ◽  
P Element ◽  
Genetic Studies ◽  
Germline Differentiation ◽  
Males And Females ◽  
Bag Of Marbles ◽  
Differentiation And Proliferation

Abstract We present the cloning and characterization of mei-P26, a novel P-element-induced exchange-defective female meiotic mutant in Drosophila melanogaster. Meiotic exchange in females homozygous for mei-P261 is reduced in a polar fashion, such that distal chromosomal regions are the most severely affected. Additional alleles generated by duplication of the P element reveal that mei-P26 is also necessary for germline differentiation in both females and males. To further assess the role of mei-P26 in germline differentiation, we tested double mutant combinations of mei-P26 and bag-of-marbles (bam), a gene necessary for the control of germline differentiation and proliferation in both sexes. A null mutation at the bam locus was found to act as a dominant enhancer of mei-P26 in both males and females. Interestingly, meiotic exchange in mei-P261; bamΔ86/+ females is also severely decreased in comparison to mei-P261 homozygotes, indicating that bam affects the meiotic phenotype as well. These data suggest that the pathways controlling germline differentiation and meiotic exchange are related and that factors involved in the mitotic divisions of the germline may regulate meiotic recombination.

Cerebral autosomo-dominant arteriopathy with subcortical infarctions and leukoencephalopathy

2021 ◽  
Vol 26 (5) ◽  
pp. 30-38
Author(s):  
E. A. Savchuk ◽  
E. P. Golubinskaya ◽  
T. N. Shcherbinina ◽  
G. Yu. Voronin ◽  
E. O. Savchuk ◽  
...  
Keyword(s):  
Clinical Case ◽  
Structural Changes ◽  
Light And Electron Microscopy ◽  
Joint Work ◽  
Genetic Studies ◽  
Small Vessels ◽  
Clinical Case Study ◽  
The Family ◽  
Probable Diagnosis

The article presents an analysis of the literature and a clinical case of a rare disease from the group of diseases of small vessels — cerebral autosomal dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL).It is based on the deposition of osmiophilic granulation material in vessels of small and medium caliber. A mutation in the NOTCH3 gene on chromosome 19p13 leads to significant structural changes in the walls of small arteries due to impaired differentiation and maturation of smooth muscle cells.CADASIL is characterized by four key symptoms: migraines, recurrent ischemic strokes, mental disorders, and cognitive decline. The clinical case study is presented from the standpoint of a multidisciplinary patient-oriented approach of joint work of neurologists and morphologists. On the basis of clinical and laboratory criteria, a probable diagnosis was made. To confirm it, a muscle biopsy was performed (a musculocutaneous flap from the inner surface of the thighs and forearms), in order to conduct light and electron microscopy. The details of the results of the morphological study, which made it possible to verify the patient’s diagnosis, are presented. Differential diagnostic judgments are presented and recommendations for genetic studies in the family, prognosis and treatment of the patient are given.

Trends in tourism under economic uncertainty

2020 ◽  
pp. 135481662090960 ◽  
Author(s):  
Khalid Khan ◽  
Chi-Wei Su ◽  
Yi-Dong Xiao ◽  
Haotian Zhu ◽  
Xiaoyan Zhang
Keyword(s):  
Gravity Model ◽  
Structural Changes ◽  
Exchange Rate Regime ◽  
Causal Link ◽  
Policy Uncertainty ◽  
Time Varying ◽  
The United Kingdom ◽  
Window Technique ◽  
Rolling Window ◽  
Negative Effect

We use the gravity model to examine the causal link between economic policy uncertainty (EPU) and inbound tourism (ITM) in the United Kingdom. The results for the full sample demonstrate that EPU Granger causes ITM. This finding shows that association is misappropriated due to structural changes. We apply the time-varying rolling window technique to revisit the dynamic association between EPU and ITM. The findings for the subsamples indicate that EPU has a negative effect on ITM. In contrast, ITM has a positive effect on EPU in the subsamples. These results support the gravity model, which states that as EPU increases, the level of ITM decreases. The results have noteworthy implications for policymakers in the form of consistency in policies and short-term shock forecasting that is capable of greater shock-absorbing capacity to lessen the revocation of tourist programs. A stable exchange rate regime in the destination country will make tourism cheaper and more attractive to tourists. Decision-makers should consider time-varying attributes to establish tourism activities for effective and accurate predictions.

Risk of damage to tomato crops by the generalist zoophytophagous predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae)

2009 ◽  
Vol 100 (1) ◽  
pp. 105-115 ◽  
Author(s):  
J. Arnó ◽  
C. Castañé ◽  
J. Riudavets ◽  
R. Gabarra
Keyword(s):  
Vegetative Growth ◽  
Insect Pests ◽  
High Capacity ◽  
Lower Number ◽  
Generalist Predator ◽  
Extreme Conditions ◽  
Tomato Crop ◽  
Nesidiocoris Tenuis ◽  
Negative Effect ◽  
Prey Scarcity

AbstractNesidiocoris tenuis (Reuter) (Hem. Miridae) is a native zoophytophagous predator of the Mediterranean region, and its populations colonize tomato crops when they are not heavily treated with insecticides. This generalist predator has a high capacity for controlling insect pests, and it is currently commercially produced and released in some areas to control Bemisia tabaci (Gennadius) (Hem. Aleyrodidae). However, its status as a pest and/or as beneficial is controversial. Therefore, the aim of this study was to evaluate the risk of damage to tomatoes in extreme conditions of prey scarcity, as well as high predator populations. Three predator densities were tested in a greenhouse cage experiment during a summer tomato crop. The crop did not display any negative effect caused by the predators during the first six weeks of interaction, independently of the density released. However, subsequently, the effect was dramatic, both on the vegetative growth of the plant and on the production of fruits. The reduction in vegetative growth was located at truss eight and it was expressed mainly by a lower number of leaves and a shorter length of the shoot above the truss. There was a significant reduction of yield with a lower number of fruits collected and a smaller mean weight, although this was not observable until truss seven. It seems that feeding on the plant by this mirid bug competed with the vegetative growth and fruiting processes of the plant in the extreme conditions of prey shortage maintained in our experiment.

scholarly journals Nonmigraine-associated TRESK K+ channel variant C110R does not increase the excitability of trigeminal ganglion neurons

2014 ◽  
Vol 112 (3) ◽  
pp. 568-579 ◽  
Author(s):  
Zhaohua Guo ◽  
Ping Liu ◽  
Fei Ren ◽  
Yu-Qing Cao
Keyword(s):  
Trigeminal Ganglion ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
K Channel ◽  
Genetic Studies ◽  
Negative Effect ◽  
Functional Consequences ◽  
Ganglion Neurons

Recent genetic studies suggest that dysfunction of ion channels and transporters may contribute to migraine pathophysiology. A migraine-associated frameshift mutation in the TWIK-related spinal cord K+ (TRESK) channel results in nonfunctional channels. Moreover, mutant TRESK subunits exert a dominant-negative effect on whole cell TRESK currents and result in hyperexcitability of small-diameter trigeminal ganglion (TG) neurons, suggesting that mutant TRESK may increase the gain of the neuronal circuit underlying migraine headache. However, the nonmigraine-associated TRESK C110R variant exhibits the same effect on TRESK currents as the mutant subunits in Xenopus oocytes, suggesting that dysfunction of TRESK is not sufficient to cause migraine. Here, we confirmed that the C110R variant formed nonfunctional channels and exerted a dominant-negative effect on TRESK currents in HEK293T cells, similar to the migraine-associated mutant TRESK. To compare the functional consequences of TRESK mutations/variants in a more physiological setting, we expressed the mutant TRESK and the C110R variant in cultured mouse TG neurons and investigated their effects on background K+ currents and neuronal excitability. Both mutant TRESK and the C110R variant reduced the endogenous TRESK currents in TG neurons, but the effect of the C110R variant was significantly smaller. Importantly, only TG neurons expressing mutant TRESK subunits, but not those expressing the C110R variant, exhibited a significant increase in excitability. Thus only the migraine-associated TRESK mutation, but not the C110R variant, reduces the endogenous TRESK currents to a degree that affects TG excitability. Our results support a potential causal relationship between the frameshift TRESK mutation and migraine susceptibility.

scholarly journals Does capacity increase compliance? Examining evidence from European cooperation against air pollution

2020 ◽  
Author(s):  
Andreas Kokkvoll Tveit
Keyword(s):  
Air Pollution ◽  
High Capacity ◽  
International Agreements ◽  
European Cooperation ◽  
Capacity Increase ◽  
Policy Goals ◽  
Negative Effect

Abstract Scholars commonly hypothesize that enhanced capacity—improved ability to do as agreed—increases states’ compliance with international agreements. In contrast, using a novel dataset that covers 31 states and three decades of cooperation, I find a negative effect of capacity on compliance. To help explain this seemingly counterintuitive finding, I offer a novel conjecture of the capacity–compliance relationship. In particular, I argue that the effect of capacity may vary substantially across states, because states’ intention to comply constitutes a crucial intervening variable. Among reluctant states pursuing policy goals that affect compliance negatively, high capacity may in fact cause noncompliance. I exemplify the conjecture through evidence from a high-capacity noncompliant state (Norway).

Regularities of Changes in the Mechanical Characteristics and Electrical Properties of the Reaction Furnaces Coils Material during Operation

2020 ◽  
Vol 992 ◽  
pp. 706-711
Author(s):  
E.A. Naumkin ◽  
J.N. Shermatov
Keyword(s):  
Structural Changes ◽  
Mechanical Characteristics ◽  
Diffusion Processes ◽  
Relative Magnitude ◽  
Electrical Signal ◽  
Destructive Testing ◽  
Static Tests ◽  
Negative Effect ◽  
Void Structure ◽  
Reaction Furnace

The main causes of early failure of reaction furnaces coils are diffusion processes in the material as a result of which structural changes occur, new phases are formed and void structure is formed in the surface layers of the metal, which has a negative effect on the mechanical characteristics. In this regard as a structurally sensitive method, which allows evaluating the changes occurring in the metal, the response parameters of the electrical signal are used which are sensitive to pore formation and allow predicting the zone of formation of the breaking crack. Fragments of the coils of the reaction furnaces from the radiant section, which were in operation for 750, 1300, 8000, and 10000 hours and the pipe element in the delivery condition were chosen as the objects of the study. As a result of the research a correlation between the amplitude of the first harmonic of the electrical signal output voltage with the results of static tests for tensile and impact bending was established. This happens due to the fact that during operation there is an increase in the relative impact viscosity and relative tensile strength, and the relative magnitude of the voltage amplitude of the first harmonic of the output electrical signal also increases. These results can be used as a method of mechanical properties assessment by non-destructive testing, and also they can be used to develop a criterion for the rejection of reaction furnace coils.

Variation I: Genetics

Mate Choice ◽  
2017 ◽  
Author(s):  
Gil G. Rosenthal
Keyword(s):  
Genetic Variation ◽  
Gene Structure ◽  
Infinite Number ◽  
Reverse Genetics ◽  
Forward Genetics ◽  
Genetic Models ◽  
Genetic Studies ◽  
Quantitative Genetic ◽  
Negative Effect ◽  
Genomic Regions

This chapter reviews the main approaches for characterizing preference genetics. Approaches to understanding the genetics underlying preferences (or any other phenotype) take two broad forms. The first approach consists of attempts to identify particular genes or genomic regions associated with preference variation; for preferences, this is typically done using so-called forward genetics, whereby variation in phenotype is correlated with variation in genotype. Alternatively, the effects of candidate genes on preference can be characterized using reverse genetics, whereby gene structure or function is altered to test its effect on phenotype. The second approach encompasses quantitative genetic studies that assume that the underlying genetic variation is continuous and additive. Quantitative genetic models often assume an infinite number of loci each contributing infinitely small positive or negative effect, summing to determine trait value.

High-capacity V-/Sc-/Ti-doped MnO2 for Li/MnO2 batteries and structural changes at different discharge depths

2014 ◽  
Vol 127 ◽  
pp. 115-122 ◽  
Author(s):  
Jian Zeng ◽  
Shengping Wang ◽  
Qiuling Liu ◽  
Xinrong Lei
Keyword(s):  
Structural Changes ◽  
High Capacity
Sign in / Sign up

Export Citation Format

Share Document