scholarly journals Getting to the Heart of Left–Right Asymmetry: Contributions from the Zebrafish Model

2021 ◽  
Vol 8 (6) ◽  
pp. 64
Author(s):  
Kelly A. Smith ◽  
Veronica Uribe

The heart is laterally asymmetric. Not only is it positioned on the left side of the body but the organ itself is asymmetric. This patterning occurs across scales: at the organism level, through left–right axis patterning; at the organ level, where the heart itself exhibits left–right asymmetry; at the cellular level, where gene expression, deposition of matrix and proteins and cell behaviour are asymmetric; and at the molecular level, with chirality of molecules. Defective left–right patterning has dire consequences on multiple organs; however, mortality and morbidity arising from disrupted laterality is usually attributed to complex cardiac defects, bringing into focus the particulars of left–right patterning of the heart. Laterality defects impact how the heart integrates and connects with neighbouring organs, but the anatomy of the heart is also affected because of its asymmetry. Genetic studies have demonstrated that cardiac asymmetry is influenced by left–right axis patterning and yet the heart also possesses intrinsic laterality, reinforcing the patterning of this organ. These inputs into cardiac patterning are established at the very onset of left–right patterning (formation of the left–right organiser) and continue through propagation of left–right signals across animal axes, asymmetric differentiation of the cardiac fields, lateralised tube formation and asymmetric looping morphogenesis. In this review, we will discuss how left–right asymmetry is established and how that influences subsequent asymmetric development of the early embryonic heart. In keeping with the theme of this issue, we will focus on advancements made through studies using the zebrafish model and describe how its use has contributed considerable knowledge to our understanding of the patterning of the heart.

Biology ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 120
Author(s):  
Abdalla Elbialy ◽  
Yoji Igarashi ◽  
Shuichi Asakawa ◽  
Shugo Watabe ◽  
Shigeharu Kinoshita

In our previous publication, it was shown that growth hormone (GH) excess in acromegaly affects the cell integrity of somatic cells through increased DNA damage throughout the body and impaired DNA repair pathways. Acromegaly is a hormone disorder pathological condition that develops as a result of growth hormone over-secretion from the pituitary gland. We produced a zebrafish acromegaly model to gain a better understanding of the excess GH effects at the cellular level. Here we show that the acromegaly zebrafish model progressively reduced the number of stem cells in different organs and increased oxidative stress in stem cells. Importantly, the decline in the stem cells was even more apparent than in aged fish. The controversy and debate over the use of GH as an anti-aging therapy have been going on for several years. In this study, excess GH induced aging signs such as increased senescence-associated (SA)-β-galactosidase staining of abdominal skin and similarity of the pattern of gene expression between aged and acromegaly zebrafish. Thus, this study highlights the role of excess GH in acromegaly stem cells.


Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4643-4651 ◽  
Author(s):  
P.J. Gage ◽  
H. Suh ◽  
S.A. Camper

Pitx2 is a homeodomain transcription factor that is mutated in Rieger syndrome, a haploinsufficiency disorder affecting eyes and teeth. Pitx2 also has a postulated role in left-right axis determination. We assessed the requirements for Pitx2 directly by generating hypomorphic and null alleles. Heterozygotes for either allele have eye abnormalities consistent with Rieger syndrome. The ventral body wall fails to close in embryos homozygous for the null allele, leaving the heart and abdominal organs externalized and the body axis contorted. In homozygotes for either allele, the heart tube undergoes normal, rightward looping and the stomach is positioned normally. In contrast, homozygotes for both alleles exhibit right isomerization of the lungs. Thus, Pitx2 is required for left-right asymmetry of the lungs but not other organs. Homozygotes for either allele exhibit septal and valve defects, and null homozygotes have a single atrium proving that a threshold level of Pitx2 is required for normal heart development. Null homozygotes exhibit arrest of pituitary gland development at the committed Rathke pouch stage and eye defects including optic nerve coloboma and absence of ocular muscles. This allelic series establishes that Pitx2 is required for the development of mulitple organs in a dosage-sensitive manner.


Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3281-3294 ◽  
Author(s):  
Zsolt Lele ◽  
Anja Folchert ◽  
Miguel Concha ◽  
Gerd-Jörg Rauch ◽  
Robert Geisler ◽  
...  

N-cadherin (Ncad) is a classical cadherin that is implicated in several aspects of vertebrate embryonic development, including somitogenesis, heart morphogenesis, neural tube formation and establishment of left-right asymmetry. However, genetic in vivo analyses of its role during neural development have been rather limited. We report the isolation and characterization of the zebrafish parachute (pac) mutations. By mapping and candidate gene analysis, we demonstrate that pac corresponds to a zebrafish n-cadherin (ncad) homolog. Three mutant alleles were sequenced and each is likely to encode a non-functional Ncad protein. All result in a similar neural tube phenotype that is most prominent in the midbrain, hindbrain and the posterior spinal cord. Neuroectodermal cell adhesion is altered, and convergent cell movements during neurulation are severely compromised. In addition, many neurons become progressively displaced along the dorsoventral and the anteroposterior axes. At the cellular level, loss of Ncad affects β-catenin stabilization/localization and causes mispositioned and increased mitoses in the dorsal midbrain and hindbrain, a phenotype later correlated with enhanced apoptosis and the appearance of ectopic neurons in these areas. Our results thus highlight novel and crucial in vivo roles for Ncad in the control of cell convergence, maintenance of neuronal positioning and dorsal cell proliferation during vertebrate neural tube development.


Life ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Srikanth Elesela ◽  
Nicholas W. Lukacs

Viral diseases account for an increasing proportion of deaths worldwide. Viruses maneuver host cell machinery in an attempt to subvert the intracellular environment favorable for their replication. The mitochondrial network is highly susceptible to physiological and environmental insults, including viral infections. Viruses affect mitochondrial functions and impact mitochondrial metabolism, and innate immune signaling. Resurgence of host-virus interactions in recent literature emphasizes the key role of mitochondria and host metabolism on viral life processes. Mitochondrial dysfunction leads to damage of mitochondria that generate toxic compounds, importantly mitochondrial DNA, inducing systemic toxicity, leading to damage of multiple organs in the body. Mitochondrial dynamics and mitophagy are essential for the maintenance of mitochondrial quality control and homeostasis. Therefore, metabolic antagonists may be essential to gain a better understanding of viral diseases and develop effective antiviral therapeutics. This review briefly discusses how viruses exploit mitochondrial dynamics for virus proliferation and induce associated diseases.


1972 ◽  
Vol 21 (3) ◽  
pp. 204-210 ◽  
Author(s):  
Ch. Susanne

SummaryThe results are presented of a method of generalized distances calculated by a noncentral χ2 test and applied to compare 63 twin pairs and 196 sib pairs. The advantage of this method in biometrical analysis lies in the fact that several measurements can be utilised simultaneously. Besides, it takes into account the distance of each relative to the centre of the population and also has the advantage of permitting the comparison of distances between pairs of relatives whatever their age or sex.Generalized distances were calculated for four measurements of the head, five of the body and eleven of the face. For all three sets of measurements the influence of genetical factors was demonstrated. The body seems less influenced by environmental factors and more conditioned by genetic ones.


2018 ◽  
Vol 2 (47) ◽  
pp. 10-15
Author(s):  
Danuta Łoboda ◽  
Karolina Simionescu ◽  
Anna Szajerska-Kurasiewicz ◽  
Dorota Lasyk ◽  
Grzegorz Jarosiński ◽  
...  

Cardiac arrhythmias during sleep are reported in almost half of the population suffering from obstructive sleep apnea (OSA). The most common are bradyarrhythmias and atrial fibrillation whereas premature ventricular contractions and nonsustained ventricular tachycardia are less frequent. The risk of arrhythmia is proportional to the body mass index (BMI), number of respiratory events per hour of sleep described with apnea/hypopnea index (AHI) and the level of oxygen desaturation during these episodes. Continuous positive airway pressure (CPAP) treatment in OSA reduces the incidence of cardiac arrhythmias therefore reduce mortality and morbidity from cardiovascular disease.


2021 ◽  
Vol 118 (48) ◽  
pp. e2109210118
Author(s):  
Régis Chirat ◽  
Alain Goriely ◽  
Derek E. Moulton

Snails are model organisms for studying the genetic, molecular, and developmental bases of left–right asymmetry in Bilateria. However, the development of their typical helicospiral shell, present for the last 540 million years in environments as different as the abyss or our gardens, remains poorly understood. Conversely, ammonites typically have a bilaterally symmetric, planispiraly coiled shell, with only 1% of 3,000 genera displaying either a helicospiral or a meandering asymmetric shell. A comparative analysis suggests that the development of chiral shells in these mollusks is different and that, unlike snails, ammonites with asymmetric shells probably had a bilaterally symmetric body diagnostic of cephalopods. We propose a mathematical model for the growth of shells, taking into account the physical interaction during development between the soft mollusk body and its hard shell. Our model shows that a growth mismatch between the secreted shell tube and a bilaterally symmetric body in ammonites can generate mechanical forces that are balanced by a twist of the body, breaking shell symmetry. In gastropods, where a twist is intrinsic to the body, the same model predicts that helicospiral shells are the most likely shell forms. Our model explains a large diversity of forms and shows that, although molluscan shells are incrementally secreted at their opening, the path followed by the shell edge and the resulting form are partly governed by the mechanics of the body inside the shell, a perspective that explains many aspects of their development and evolution.


Author(s):  
Anastasiya S. Kazitskaya ◽  
Oleg I. Bondarev ◽  
Maria S. Bugaeva ◽  
Anna G. Zhukova ◽  
Tatyana K. Yadykina

Introduction. The combined impact of unfavorable factors of the production environment in miners leads to the development of associated pathology of the bronchopulmonary and cardiovascular systems, the predisposition to which depends on the individual susceptibility of the body. In this regard, it is important to comprehensively study the pathogenetic mechanisms underlying the formation and course of occupational and work-related diseases for a personalized approach to the diagnosis, prevention and therapy of this pathology. The purpose of this study was to study the mechanisms of damage to the cardiovascular system in miners with dust lung pathology on the basis of morphological and genetic studies. Materials and methods. For genetic studies, venous blood drawing was conducted in 190 Kuzbass miners. The main group included 126 miners of the main professions with the previously proven diagnosis "dust lung pathology", the comparison group consisted of 64 workers without a proven diagnosis working in similar sanitary and hygienic conditions. Morphometric studies were carried out using autopsy material obtained during 80 forensic medical examinations of miners in the Kemerovo region. All the miners were divided into 4 groups depending on their underground work experience. The control group was formed from 20 cases of forensic medical examinations of men who died in road accidents and did not have organ pathology according to the results of autopsies. Results. The study of the autopsy material revealed the presence of morphostructural changes in the vascular walls of the miners’ hearts in the form of hypertrophy of the smooth muscle cells of the medial layers, thickening of the endothelial lining, and the development of fibroplastic changes in the perivascular zones. These changes began to form from the first years of work in the underground conditions and progressed with increasing work experience contributing to the "recalibration" of the heart vessels with the formation of the lumen "obstruction". One of the mechanisms of endothelial damage in miners was a change in the expression of the EDN1 gene, which regulates the synthesis of endothelin-1. The risk and resistance genotypes of the development of dust lung pathology for the rs5370 polymorphism of the EDN1 gene were identified. Morphostructural rearrangement of the endothelium in the combination with its pathological activation contributed to the occurrence of endothelial dysfunction in miners. Conclusions. The conducted studies of the parameters of the vascular endothelium indicate its key role in the pathogenesis of bronchopulmonary and cardiovascular pathology in miners of the main professions. Getting into the body of workers, particles of coal-rock dust lead to morphostructural rearrangement of the cells of the endothelial layer and its pathological activation. The contribution of molecular and genetic mechanisms to the development of occupational lung pathology and associated diseases of the circulatory system in miners is revealed. Ethics. The studies were carried out in compliance with the ethical standards of the Bioethical Committee of the Research Institute for Complex Problems of Hygiene and Occupational Diseases, elaborated on the basis of the Helsinki Declaration of the World Medical Association "Ethical Principles for Conducting Human Scientific Medical Research" as amended in 2013 and the "Rules of Clinical Practice in the Russian Federation" approved by the Order of the Ministry of Health of the Russian Federation No. 266 dated 19.06.2003. All workers were informed about their participation in the molecular-genetic study and gave written consent to carry it out. The research of the dead miners was based on the secondary examination of blocks and ready-made histological micro-preparations of the material of the Bureau for Forensic Medical Expert Examination of the cities of Novokuznetsk, Osinniki, and Prokopyevsk. The study of pathomorphological material was carried out in accordance with the Federal Law of 21.11.2011, No. 323-FZ "On the Fundamentals of Health Protection of Citizens in the Russian Federation", in particular, with Article 67 "Carrying out pathological and anatomical autopsies", Federal Law of 12.01.1996, No. 8-FZ "On burial and funeral business" (Article 5, paragraphs 1, 2), as well as on the basis of the Order of the Ministry of Health of April 29, 1994, No. 82 "On the procedure for conducting pathological and anatomical autopsy" (Annex to the Order of the Ministry of Health and Medical Industry of 29.04.1994 No. 82), the Order of the Ministry of Health of Russia of 24.03.2016. No. 179n "On the rules for conducting pathological and anatomical examinations".


2017 ◽  
Vol 2017 ◽  
pp. 1-4 ◽  
Author(s):  
Akanksha Agrawal ◽  
Deepanshu Jain ◽  
Sameer Siddique

Cytomegalovirus (CMV) is a ubiquitous organism which can infect multiple organs of the body. In an immunocompromised patient, it can have a myriad of gastrointestinal manifestations. We report a case of recurrent hematochezia and concomitant pseudotumor in an AIDS (acquired immunodeficiency syndrome) patient attributable to CMV infection. A 62-year-old man with a history of AIDS, noncompliant with highly active antiretroviral therapy (HAART), presented with bright red blood per rectum. Index colonoscopy showed presence of multiple ulcers, colonic stenosis, and mass-like appearing lesion. Biopsy confirmed CMV infection and ruled out malignancy. Cessation of dual antiplatelet therapy and compliance with HAART lead to clinical cessation of bleeding and endoscopic healing of ulcers with complete resolution of colon mass on follow-up colonoscopy.


2021 ◽  
Vol 4 (03) ◽  
Author(s):  
Habib Ullah Rind ◽  
Nadia Iftikhar ◽  
Fazal ur Rehman ◽  
Abdul Kareem Zarkoon ◽  
Syed Mohkam ◽  
...  

The Pandemic of COVID-19 has grasped the whole world and changed dramatically, together with our social, occupational and personal life with high mortality and morbidity with other consequences since December 2019 started from Wuhan and then declared pandemic in March. It has been observed to involve every organ of the body including skin. Various skin manifestations, but most cases reported were like urticarial rash, xanthemas,  chickenpox-like vesicle, vasculitidic type, pressure sores, contact dermatitis and a single case was reported in china with skin darkening. The COVID-19 and cutaneous manifestations are recognized by physicians and dermatologist treating COVID-19. We have observed around eight cases of COVID -19 who had skin darkening in our center Baluchistan Institute of Nephrology and Urology Quetta, among these included were six dialysis technicians one chronic maintenance dialysis patient and a physician. We present the representative cases and discuss the skin manifestations of COVID-19.


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