scholarly journals Limb regeneration in salamanders: the plethodontid tale

2020 ◽  
Vol 52 ◽  
Author(s):  
Claudia M. Arenas Gómez ◽  
Jean P. Delgado
Keyword(s):  
Limb Development ◽  
Molecular Mechanisms ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
South American ◽  
Plethodontid Salamanders ◽  
History Of ◽  
Salamander Species ◽  
Generation Sequencing ◽  
Recent Sequencing

Salamanders are the only vertebrates that can regenerate limbs as adults. This makes them ideal models to investigate cellular and molecular mechanisms of tissue regeneration. Ambystoma mexicanum and Nothopthalmus viridescens have long served as primary salamander models of limb regeneration, and the recent sequencing of the axolotl genome now provides a blueprint to mine regeneration insights from other salamander species. In particular, there is a need to study South American plethodontid salamanders that present different patterns of limb development and regeneration. A broader sampling of species using next-generation sequencing approaches is needed to reveal shared and unique mechanisms of regeneration, and more generally, the evolutionary history of salamander limb regeneration.

Skeletal patterns in the autopodium of native and regenerated limbs of the larval axolotl, Ambystoma mexicanum

1991 ◽  
Vol 69 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Steven R. Scadding
Keyword(s):  
Vitamin A ◽  
Significant Variation ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum ◽  
Skeletal Patterning ◽  
Skeletal Pattern ◽  
Limb Pattern ◽  
Salamander Species

The purpose of this investigation was to study the autopodial skeletal patterns that are observed in native (never regenerated) and regenerated limbs of the larval axolotl, Ambystoma mexicanum. The axolotl is used widely in limb regeneration studies, and in the regenerating axolotl limb mesopodial patterns can be modified by such factors as vitamin A administration. It is also known that other salamander species show significant variation in autopodial skeletal patterning. Hence, it seemed important to determine the type and frequency of autopodial variants in both native limbs and those that have regenerated after amputation at either the stylopodial and zeugopodial levels. The results showed that native limbs exhibited a complete skeletal pattern in the majority of cases, but that variants involving loss of a phalange or reduction in the number of carpals or tarsals occurred frequently. Regenerated limb patterns were more variable than those seen in native limbs, and limbs regenerating from zeugopodial level amputations were more variable than those regenerating from stylopodial level amputation. The significance of these observations for the development and regeneration of limb pattern is discussed.

scholarly journals Genetic Alterations of Malignant Pleural Mesothelima

Mesothelioma ◽  
2020 ◽  
Author(s):  
Benjamin Wadowski ◽  
David T. Severson ◽  
Raphael Bueno ◽  
Assunta De Rienzo
Keyword(s):  
Medical Diagnosis ◽  
Molecular Mechanisms ◽  
Asbestos Exposure ◽  
Mesothelial Cell ◽  
Latency Period ◽  
Genetic Alterations ◽  
Long Latency ◽  
History Of ◽  
Aggressive Tumor ◽  
Generation Sequencing

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor that arises from the mesothelial cells lining the pleural cavity. Asbestos is considered the major factor in the pathogenesis of this malignancy, with more than 80% of patients with a history of asbestos exposure. MPM is characterized by a long latency period, typically 20–40 years from the time of asbestos exposure to diagnosis, suggesting that multiple somatic genetic alterations are required for the tumorigenic conversion of a mesothelial cell. In the last few years, advancements in next-generation sequencing and “–omics” technologies have revolutionized the field of genomics and medical diagnosis. The focus of this chapter is to summarize recent studies which explore the molecular mechanisms underlying this disease and identify potential therapeutic targets in MPM.

Comparison of the effects of vitamin A on limb development and regeneration in the axolotl, Ambystoma mexicanum

Development ◽  
1986 ◽  
Vol 91 (1) ◽  
pp. 19-34
Author(s):  
S. R. Scadding ◽  
M. Maden
Keyword(s):  
Vitamin A ◽  
Limb Development ◽  
Species Differences ◽  
Limb Regeneration ◽  
Ambystoma Mexicanum

The objective of this investigation was to compare the effect of vitamin A on limb development and limb regeneration in the same animal, at the same time, thus eliminating the possibility that species differences or different rates of uptake between animals would influence the results. Axolotl larvae had both right limbs amputated and then were treated with retinol palmitate by immersion at 60 or 300 mg 1−1 for 4 or 10 days. Intact left developing limbs at the cone, two-digit, or four-digit stages responded to the treatment by deletion of skeletal elements producing hypomorphic limbs. Severity of the deletions was correlated with higher dose, longer times, and earlier stages of limb development. In contralateral right regenerating limbs, the effect of the same treatment was to cause various degrees of proximodistal duplication as well as occasional hypomorphic regenerates. Thus, there is a marked difference in response to vitamin A between developing and regenerating limbs. The implications of this observation are discussed especially with respect to the underlying morphogenetic mechanisms.

scholarly journals Early evolution of limb regeneration in tetrapods: evidence from a 300-million-year-old amphibian

2014 ◽  
Vol 281 (1794) ◽  
pp. 20141550 ◽  
Author(s):  
Nadia B. Fröbisch ◽  
Constanze Bickelmann ◽  
Florian Witzmann
Keyword(s):  
Comparative Studies ◽  
Limb Development ◽  
Molecular Mechanisms ◽  
Limb Regeneration ◽  
Regenerative Capacity ◽  
Unique Pattern ◽  
Research Designs ◽  
Regenerative Activity ◽  
Distant Relative ◽  
New Framework

Salamanders are the only tetrapods capable of fully regenerating their limbs throughout their entire lives. Much data on the underlying molecular mechanisms of limb regeneration have been gathered in recent years allowing for new comparative studies between salamanders and other tetrapods that lack this unique regenerative potential. By contrast, the evolution of animal regeneration just recently shifted back into focus, despite being highly relevant for research designs aiming to unravel the factors allowing for limb regeneration. We show that the 300-million-year-old temnospondyl amphibian Micromelerpeton , a distant relative of modern amphibians, was already capable of regenerating its limbs. A number of exceptionally well-preserved specimens from fossil deposits show a unique pattern and combination of abnormalities in their limbs that is distinctive of irregular regenerative activity in modern salamanders and does not occur as variants of normal limb development. This demonstrates that the capacity to regenerate limbs is not a derived feature of modern salamanders, but may be an ancient feature of non-amniote tetrapods and possibly even shared by all bony fish. The finding provides a new framework for understanding the evolution of regenerative capacity of paired appendages in vertebrates in the search for conserved versus derived molecular mechanisms of limb regeneration.

scholarly journals Next Generation Sequencing for the Prediction of the Antibiotic Resistance in Helicobacter pylori: A Literature Review

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 437
Author(s):  
Ilaria Maria Saracino ◽  
Matteo Pavoni ◽  
Angelo Zullo ◽  
Giulia Fiorini ◽  
Tiziana Lazzarotto ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Next Generation Sequencing ◽  
Literature Review ◽  
Molecular Mechanisms ◽  
World Health ◽  
Next Generation ◽  
Culture Methods ◽  
Phenotypic Resistance ◽  
H Pylori ◽  
Generation Sequencing

Background and aims: Only a few antimicrobials are effective against H. pylori, and antibiotic resistance is an increasing problem for eradication therapies. In 2017, the World Health Organization categorized clarithromycin resistant H. pylori as a “high-priority” bacterium. Standard antimicrobial susceptibility testing can be used to prescribe appropriate therapies but is currently recommended only after the second therapeutic failure. H. pylori is, in fact, a “fastidious” microorganism; culture methods are time-consuming and technically challenging. The advent of molecular biology techniques has enabled the identification of molecular mechanisms underlying the observed phenotypic resistance to antibiotics in H. pylori. The aim of this literature review is to summarize the results of original articles published in the last ten years, regarding the use of Next Generation Sequencing, in particular of the whole genome, to predict the antibiotic resistance in H. pylori.Methods: a literature research was made on PubMed. The research was focused on II and III generation sequencing of the whole H. pylori genome. Results: Next Generation Sequencing enabled the detection of novel, rare and complex resistance mechanisms. The prediction of resistance to clarithromycin, levofloxacin and amoxicillin is accurate; for other antimicrobials, such as metronidazole, rifabutin and tetracycline, potential genetic determinants of the resistant status need further investigation.

scholarly journals MicroRNAs from Snellenius manilae bracovirus regulate innate and cellular immune responses of its host Spodoptera litura

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Cheng-Kang Tang ◽  
Chih-Hsuan Tsai ◽  
Carol-P. Wu ◽  
Yu-Hsien Lin ◽  
Sung-Chan Wei ◽  
...  
Keyword(s):  
Immune Responses ◽  
Spodoptera Litura ◽  
Molecular Mechanisms ◽  
Innate Immune ◽  
Sequencing Analysis ◽  
Innate Immune Responses ◽  
Cellular Immune Responses ◽  
Next Generation Sequencing Analysis ◽  
Cellular Immune ◽  
Generation Sequencing

AbstractTo avoid inducing immune and physiological responses in insect hosts, parasitoid wasps have developed several mechanisms to inhibit them during parasitism, including the production of venom, specialized wasp cells, and symbioses with polydnaviruses (PDVs). These mechanisms alter the host physiology to give the wasp offspring a greater chance of survival. However, the molecular mechanisms for most of these alterations remain unclear. In the present study, we applied next-generation sequencing analysis and identified several miRNAs that were encoded in the genome of Snellenius manilae bracovirus (SmBV), and expressed in the host larvae, Spodoptera litura, during parasitism. Among these miRNAs, SmBV-miR-199b-5p and SmBV-miR-2989 were found to target domeless and toll-7 in the host, which are involved in the host innate immune responses. Microinjecting the inhibitors of these two miRNAs into parasitized S. litura larvae not only severely decreased the pupation rate of Snellenius manilae, but also restored the phagocytosis and encapsulation activity of the hemocytes. The results demonstrate that these two SmBV-encoded miRNAs play an important role in suppressing the immune responses of parasitized hosts. Overall, our study uncovers the functions of two SmBV-encoded miRNAs in regulating the host innate immune responses upon wasp parasitism.

scholarly journals Genomics of ageing in twins

2014 ◽  
Vol 73 (4) ◽  
pp. 526-531 ◽  
Author(s):  
Massimo Mangino
Keyword(s):  
Molecular Mechanisms ◽  
Twin Studies ◽  
Later Life ◽  
Twin Design ◽  
The Past ◽  
Human Ageing ◽  
Classical Twin Design ◽  
Environmental Component ◽  
Early Life Events ◽  
Generation Sequencing

Ageing is a complex multifactorial process, reflecting the progression of all degenerative pathways within an organism. Due to the increase of life expectancy, in recent years, there is a pressing need to identify early-life events and risk factors that determine health outcomes in later life. So far, genetic variation only explains ~20–25 % of the variability of human survival to age 80+. This clearly implies that other factors (environmental, epigenetic and lifestyle) contribute to lifespan and the rate of healthy ageing within an individual. Twin studies in the past two decades proved to be a very powerful tool to discriminate the genetic from the environmental component. The aim of this review is to describe the basic concepts of the twin study design and to report some of the latest studies in which high-throughput technologies (e.g. genome/epigenome-wide assay, next generation sequencing, MS metabolic profiling) combined with the classical twin design have been applied to the analysis of novel ‘omics’ to further understand the molecular mechanisms of human ageing.

Memory impairment induced by amphetamine derivatives in laboratory animals and in humans: a review

2012 ◽  
Vol 3 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Jordi Camarasa ◽  
Teresa Rodrigo ◽  
David Pubill ◽  
Elena Escubedo
Keyword(s):  
Illicit Drugs ◽  
Molecular Mechanisms ◽  
Memory Performance ◽  
Laboratory Animals ◽  
Club Drugs ◽  
Synthetic Drugs ◽  
History Of ◽  
Amphetamine Derivatives ◽  
Considerable Body

AbstractThe 20th century brought with it the so-called club drugs (the most notorious being amphetamine derivatives), which are used by young adults at all-night dance parties. Methamphet­amine and 3,4-methylenedioxymethamphetamine (MDMA or ecstasy) are synthetic drugs with stimulant and psychoactive properties that belong to the amphetamine family. Here, we have reviewed the literature about the cognitive impairment induced by these two amphetamine derivatives and the preclinical and clinical outcomes. Although there is controversial evidence about the effect of methamphetamine and MDMA on learning and memory in laboratory animals, results from published papers demonstrate that amphetamines cause long-term impairment of cognitive functions. A large number of pharmacological receptors have been studied and screened as targets of amphetamine-induced cognitive dysfunction, and extensive research efforts have been invested to provide evidence about the molecular mechanisms behind these cognitive deficits. In humans, there is a considerable body of evidence indicating that methamphetamine and MDMA seriously disrupt memory and learning processes. Although an association between the impairments of memory performance and a history of recreational amphetamine ingestion has also been corroborated, a number of methodological difficulties continue to hamper research in this field, the most important being the concomitant use of other illicit drugs.

Citral, an inhibitor of retinoic acid synthesis, modifies pattern formation during limb regeneration in the axolotl Ambystoma mexicanum

1999 ◽  
Vol 77 (11) ◽  
pp. 1835-1837 ◽  
Author(s):  
Steven R Scadding
Keyword(s):  
Retinoic Acid ◽  
Pattern Formation ◽  
Limb Regeneration ◽  
Acid Synthesis ◽  
Ambystoma Mexicanum

While the effects of exogenous retinoids on amphibian limb regeneration have been studied extensively, the role of endogenous retinoids is not clear. Hence, I wished to investigate the role of endogenous retinoic acid during axolotl limb regeneration. Citral is a known inhibitor of retinoic acid synthesis. Thus, I treated regenerating limbs of the larval axolotl Ambystoma mexicanum with citral. The result of this inhibition of retinoic acid synthesis was that limb regeneration became extremely irregular and hypomorphic, with serious pattern defects, or was inhibited altogether. I conclude that endogenous retinoic acid plays an important role in pattern formation during limb regeneration.

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