scholarly journals Variation in Base Composition Underlies Functional and Evolutionary Divergence in Non-LTR Retrotransposons

2019 ◽  
Author(s):  
Robert P. Ruggiero ◽  
Stéphane Boissinot
Keyword(s):  
Deleterious Effect ◽  
Base Composition ◽  
Regulatory Mechanism ◽  
Extended Period ◽  
Evolutionary Divergence ◽  
Ltr Retrotransposons ◽  
Evolutionary Time ◽  
Nucleotide Content ◽  
L1 Element

ABSTRACTBackgroundNon-LTR retrotransposons often exhibit base composition that is markedly different from the nucleotide content of their host’s gene. For instance, the mammalian L1 element is AT-rich with a strong A bias on the positive strand, which results in a reduced transcription. It is plausible that the A-richness of mammalian L1 is a self-regulatory mechanism reflecting a trade-off between transposition efficiency and the deleterious effect of L1 on its host. We examined if the A-richness of L1 is a general feature of non-LTR retrotransposons or if different clades of elements have evolved different nucleotide content. We also investigated if elements belonging to the same clade evolved towards different base composition in different genomes or if elements from the same clades evolved towards similar base composition in the same genome.ResultsWe found that non-LTR retrotransposons differ in base composition among clades within the same host but also that elements belonging to the same clade differ in base composition among hosts. We showed that nucleotide content remains constant within the same host over extended period of evolutionary time, despite mutational patterns that should drive nucleotide content away from the observed base composition.ConclusionsOur results suggest that base composition is evolving under selection and may be reflective of the long-term co-evolution between non-LTR retrotransposons and their host. Finally, the coexistence of elements with drastically different base composition suggests that these elements may be using different strategies to persist and multiply in the genome of their host.

scholarly journals Long-Term Cryopreservation Does Not Affect Quality of Peripheral Blood Stem Cell Grafts: A Comparative Study of Native, Short-Term and Long-Term Cryopreserved Haematopoietic Stem Cells

2021 ◽  
Vol 30 ◽  
pp. 096368972110360
Author(s):  
Daniel Lysak ◽  
Michaela Brychtová ◽  
Martin Leba ◽  
Miroslava Čedíková ◽  
Daniel Georgiev ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Statistical Significance ◽  
Extended Period ◽  
High Dose ◽  
Atp Production ◽  
Cd34 Cells ◽  
Negative Effect

Cryopreserved haematopoietic progenitor cells are used to restore autologous haematopoiesis after high dose chemotherapy. Although the cells are routinely stored for a long period, concerns remain about the maximum storage time and the possible negative effect of storage on their potency. We evaluated the effect of cryopreservation on the quality of peripheral stem cell grafts stored for a short (3 months) and a long (10 years) period and we compared it to native products.The viability of CD34+ cells remained unaffected during storage, the apoptotic cells were represented up to 10% and did not differ between groups. The clonogenic activity measured by ATP production has decreased with the length of storage (ATP/cell 1.28 nM in native vs. 0.63 in long term stored products, P < 0.05). Only borderline changes without statistical significance were detected when examining mitochondrial and aldehyde dehydrogenase metabolic activity and intracellular pH, showing their good preservation during cell storage. Our experience demonstrates that cryostorage has no major negative effect on stem cell quality and potency, and therefore autologous stem cells can be stored safely for an extended period of at least 10 years. On the other hand, long term storage for 10 years and longer may lead to mild reduction of clonogenic capacity. When a sufficient dose of stem cells is infused, these changes will not have a clinical impact. However, in products stored beyond 10 years, especially when a low number of CD34+ cells is available, the quality of stem cell graft should be verified before infusion using the appropriate potency assays.

scholarly journals How Do Trade-Offs and Synergies between Ecosystem Services Change in the Long Period? The Case Study of Uxin, Inner Mongolia, China

2019 ◽  
Vol 11 (21) ◽  
pp. 6041 ◽  
Author(s):  
Zhang ◽  
Li ◽  
Buyantuev ◽  
Bao ◽  
Zhang
Keyword(s):  
Ecosystem Services ◽  
Inner Mongolia ◽  
Stepwise Regression ◽  
Driving Forces ◽  
Extended Period ◽  
Trade Offs ◽  
Development And Utilization ◽  
Long Term Trends

Ecosystem services management should often expect to deal with non-linearities due to trade-offs and synergies between ecosystem services (ES). Therefore, it is important to analyze long-term trends in ES development and utilization to understand their responses to climate change and intensification of human activities. In this paper, the region of Uxin in Inner Mongolia, China, was chosen as a case study area to describe the spatial distribution and trends of 5 ES indicators. Changes in relationships between ES and driving forces of dynamics of ES relationships were analyzed for the period 1979–2016 using a stepwise regression. We found that: the magnitude and directions in ES relationships changed during this extended period; those changes are influenced by climate factors, land use change, technological progress, and population growth.

Acute Pancreatitis Has a Long-term Deleterious Effect on Physical Health Related Quality of Life

2017 ◽  
Vol 15 (9) ◽  
pp. 1435-1443.e2 ◽  
Author(s):  
Jorge D. Machicado ◽  
Amir Gougol ◽  
Kimberly Stello ◽  
Gong Tang ◽  
Yongseok Park ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Acute Pancreatitis ◽  
Physical Health ◽  
Deleterious Effect ◽  
Health Related Quality ◽  
Related Quality ◽  
Health Related

scholarly journals Evaluation of Two Supplemented Culture Media for Long-Term, Room-Temperature Preservation ofStreptococcus pneumoniaeStrains

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Beatriz Quintero Moreno ◽  
María Araque ◽  
Evelyn Mendoza
Keyword(s):  
Survival Time ◽  
Room Temperature ◽  
Culture Media ◽  
Skim Milk ◽  
Extended Period ◽  
Phenotypic Characteristics ◽  
Genetic Profiles ◽  
Sequence Types ◽  
Over Time

Objective. To produce two supplemented agar types in order to store pneumococci for several months at room temperature.Methods. Todd-Hewitt/Hemoglobin/Yeast/Charcoal/Agar (TH-HYC) and Todd-Hewitt/Skim-Milk/Yeast/Charcoal/Agar (TH-SYC) were used to prepare two supplemented agar types. Nineteen pneumococci isolated from patients or asymptomatic carriers displaying diverse serotypes and multilocus sequence types (MLST) were subcultured and stored onto supplemented agar types, in four different tests, at room temperature.Findings. At the end of all tests (4–6 months) all noncontaminated subcultures were viable and maintained all phenotypic characteristics. Survival-time curves revealed a slow decrease of viable CFU over time on agar types, but at the end the number of viable CFU was satisfactory (≥2+ of growth). Decreasing of CFU was significantly higher for clinical versus nasopharyngeal isolates. Subcultures contamination rates were 6.25% and 14.58% after 2 and 6 months of storage, respectively.Conclusion. TH-HYC and TH-SYC agar types allowed the viability of pneumococci with several serotypes, MLST, and genetic profiles, after 6 months of storage at room temperature. We consider that these agar types are a valid alternative to preserve pneumococci over an extended period, especially when methods as cryopreservation or lyophilization are not available, and are useful for transporting strains between laboratories.

An extended period of episodic northern mid-latitude glaciation on Mars during the Middle to Late Amazonian: Implications for long-term obliquity history

Geology ◽  
2014 ◽  
Vol 42 (9) ◽  
pp. 763-766 ◽  
Author(s):  
Caleb I. Fassett ◽  
Joseph S. Levy ◽  
James L. Dickson ◽  
James W. Head
Keyword(s):  
Extended Period

scholarly journals Comets (Existing Populations)

1994 ◽  
Vol 160 ◽  
pp. 77-94
Author(s):  
Ľ. Kresák
Keyword(s):  
Kuiper Belt ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Survival Times ◽  
Evolutionary Time ◽  
Origin And Evolution ◽  
History Of ◽  
The Individual ◽  
Evolutionary Paths

The definition, population, extent, origin and evolution of the individual subsystems of comets and transitions between them are discussed, together with presentation of the relevant statistical data and their changes with time. The largest outer subsystems are unobservable, but their existence is documented by the necessity of progressive replenishment of the observable populations, with limited survival times. There is persuasive evidence for two different evolutionary paths, one from the Oort cloud and another from the Kuiper belt. While the extent and accuracy of the data available is increasing rapidly, the Jupiter family of comets is the only one for which the evolutionary time scales do not exceed by many orders of magnitude the history of astronomical observations. The individual comet populations differ from one another not only by the distribution of orbits, but also by the size distribution and aging rate of their members. Their dynamical evolution is coupled with disintegration processes, which make it questionable whether the present state can be interpreted as a long-term average.

scholarly journals Immunomodulatory Effects of Tryptophan Metabolism in the Glioma Tumor Microenvironment

2021 ◽  
Vol 12 ◽  
Author(s):  
Yang Xu ◽  
Huikai Zhang ◽  
Qian Sun ◽  
Rongxin Geng ◽  
Fanen Yuan ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Tumor Cells ◽  
Immune Regulation ◽  
Acid Metabolism ◽  
Regulatory Mechanism ◽  
Term Treatment ◽  
Tryptophan Metabolism ◽  
Long Term Treatment ◽  
Regulation Mechanisms

Gliomas are the most common primary malignant tumor in adults’ central nervous system. While current research on glioma treatment is advancing rapidly, there is still no breakthrough in long-term treatment. Abnormalities in the immune regulatory mechanism in the tumor microenvironment are essential to tumor cell survival. The alteration of amino acid metabolism is considered a sign of tumor cells, significantly impacting tumor cells and immune regulation mechanisms in the tumor microenvironment. Despite the fact that the metabolism of tryptophan in tumors is currently discussed in the literature, we herein focused on reviewing the immune regulation of tryptophan metabolism in the tumor microenvironment of gliomas and analyzed possible immune targets. The objective is to identify potential targets for the treatment of glioma and improve the efficiency of immunotherapy.

Impact of clonal evolution on the biological diversity of Trypanosoma cruzi

Parasitology ◽  
1997 ◽  
Vol 114 (3) ◽  
pp. 213-218 ◽  
Author(s):  
J.-P. LAURENT ◽  
C. BARNABE ◽  
V. QUESNEY ◽  
S. NOEL ◽  
M. TIBAYRENC
Keyword(s):  
Trypanosoma Cruzi ◽  
Biological Diversity ◽  
Clonal Evolution ◽  
Evolutionary Divergence ◽  
Biological Variability ◽  
Profound Impact ◽  
Applied Study ◽  
Biological Differences

Trypanosoma cruzi, the agent of Chagas' disease, exhibits considerable biological variability. Moreover, it has been postulated that populations of this protozoan are subdivided into natural clones, which can be separated from each other by considerable levels of evolutionary divergence. The authors have proposed that this long-term clonal evolution may have a profound impact on Trypanosoma cruzi biological diversity. In order to test this hypothesis, 16 T. cruzi stocks representing 3 major clonal genotypes of the parasite were analysed for 8 different in vitro biological parameters. The overall results show a strong statistical linkage between genetic and biological differences. This is in agreement with the working hypothesis, although a notable biological variability is observable among the stocks of each of the 3 major clonal genotypes. The authors propose that T. cruzi genetic variability must be taken into account in any applied study dealing with this parasite.

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