Validity of Xiphophorus Fish as Models for Human Disease
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Xiphophorus is the one of the oldest animal systems for studying melanoma. In this article, the authors summarize current Xiphophorus models for other human diseases. They review how Xiphophorus fishes and their interspecies hybrids can be used for studying human diseases and highlight research opportunities enabled by these unique models (both established and emerging). They identified several emerging Xiphophorus models, including for albinism, micromelanophore pigmentation, fin regeneration, and diet-induced obesity.
Blastocyst Development After Fertilization with In Vitro Spermatids Derived From Nonhuman Primate Embryonic Stem Cells
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Rhesus macaque pluripotent stem cells were differentiated into spermatogenic germ cell linages and matured in vitro to form spermatids that were capable of fertilizing oocytes (female or germ cells involved in reproduction) by intracytoplasmic spermatid injection (i.e., the egg is fertilized outside the body and the sperm is injected through a needle into the egg). Successful in vitro preimplantation embryo development was observed in approximately 12% of zygotes. The data suggest potential mechanisms to address male infertility.
Multiplexed Drug-Based Selection and Counterselection Genetic Manipulations in Drosophila
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Many highly efficient methods exist which enable transgenic flies to contribute to diagnostics and therapeutics for human diseases. In this study, researchers describe a drug-based genetic platform with four selection and two counterselection markers, increasing transgenic efficiency by more than 10-fold compared to established methods in flies. Researchers also developed a plasmid library to adapt this technology to other model organisms.
Cryopreservation Method for Drosophila melanogaster Embryos
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Drosophila melanogaster is a premier model for biomedical research. However, preservation of Drosophila stocks is labor intensive and costly. Researchers at University of Minnesota reported an efficient method for cryopreservation by optimizing key steps including embryo permeabilization and cryoprotectant agent loading.
Establishing an Immunocompromised Porcine Model of Human Cancer for Novel Therapy Development with Pancreatic Adenocarcinoma and Irreversible Electroporation
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Efficacious interventions to treat pancreatic cancer lack a preclinical model to recapitulate patients' anatomy and physiology. The authors developed RAG2/IL2RG deficient pigs using CRISPR/Cas9 with the novel application of cancer xenograft studies of human pancreatic adenocarcinoma. These pigs were successfully generated using on-demand genetic modifications in embryos. Human Panc01 cells injected into the ears of RAG2/IL2RG deficient pigs demonstrated 100% engraftment.
Lung Expression of Human Angiotensin-Converting Enzyme 2 Sensitizes the Mouse to SARS-CoV-2 Infection
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A rapidly deployable mouse model that recapitulates a disease caused by a novel pathogen would be a valuable research tool during a pandemic. Researchers were able to produce C57BL/6J mice with lung expression of human angiotensin-converting enzyme 2 (hACE2), the receptor for SARS-CoV-2. They did so by oropharyngeal delivery of a recombinant human adenovirus type 5 expressing hACE2. The transduced mice were then infected with SARS-CoV-2.
Rapid Joule Heating Improves Vitrification Based Cryopreservation
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Cryopreservation by vitrification is an effective approach for long-term preservation of biosystems, but effective vitrification often requires high concentrations of cryoprotective agent (CPA), which can be toxic. The investigators described a joule heating–based platform technology for rapid rewarming of biosystems, which allows the use of low concentrations of CPA. They demonstrated the success of this platform in cryopreservation of three model systems: adherent cells, Drosophila melanogaster embryos, and rat kidney slices with low CPA concentrations.
X Chromosome Agents of Sexual Differentiation
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Many diseases affect one sex disproportionately. A major goal of biomedical research is to understand which sex-biasing factors influence disease severity and to develop therapeutic strategies to target these factors. Two groups of such agents are sex chromosome genes and gonadal hormones. Researchers use the “four core genotypes” model to enable comparisons among animals with different sex chromosomes but the same type of sex hormones, which allows investigators to distinguish disease mechanisms influenced by the sex chromosomes.
Increased Collective Migration Correlates With Germline Stem Cell Competition in a Basal Chordate
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Cell competition is a process that compares the relative fitness of progenitor cells and results in healthier cells, contributing a higher proportion to the final tissue composition. Investigators are studying cell competition in a novel model organism, the colonial ascidian, Botryllus schlosseri. They demonstrated that winner germline stem cells show enhanced migratory ability to chemotactic cues ex vivo and that enhanced migration correlates with both expression of the Notch ligand, Jagged, and cluster size.
The Drosophila Chemokine-Like Orion Bridges Phosphatidylserine and Draper in Phagocytosis of Neurons
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Degenerating neurons can be cleared by phagocytosis triggered by “eat-me” signal phosphatidylserine (PS) and mediated by the engulfment receptor Draper (Drpr), yet the process is poorly understood. Investigators used several Drosophila models to study dendrite degeneration and demonstrated that the fly chemokine-like protein Orion binds to PS and mediates interactions between PS and Drpr to enable phagocytosis. This study identifies a link between immunomodulatory proteins and phagocytosis of neurons and reveals conserved mechanisms of clearing degenerating neurons.