Publications by authors named "Mike J McGrew"

Article Synopsis
  • A new method has been developed to directly introduce frozen embryonic gonadal germ cells (GGC) into sterile chicken hosts to help preserve chicken breeds and their genetic materials.
  • The technique is particularly efficient using male gonads, but obtaining enough viable female gonads for breeding is challenging due to limited egg production in certain chicken breeds.
  • A simplified culture method allows for high-purity GGC to be recovered from frozen 9.5-day-old embryonic gonads, supporting the biobanking of indigenous chicken breeds and potentially other bird species.
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Meat and eggs from chicken are the major source of animal protein for the human population. The cryopreservation of poultry species is needed to guarantee sustainable production. Here, we describe the existing cryopreservation technologies for avian reproductive cells using embryonic germ cells, spermatozoa and ovarian tissues.

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  • Chickens with genetic edits that alter the ANP32A protein show resistance to avian influenza, preventing infections in most cases.
  • When exposed to a stronger virus dose, some edited chickens still got infected due to mutations in the virus that adapted to the changes in the chicken's genes.
  • Further genome editing to remove additional related proteins (ANP32B and ANP32E) successfully eliminated all viral growth, highlighting the need for multiple genetic changes to effectively combat viral adaptations.
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Primordial germ cells (PGCs) are germline-restricted embryonic cells that form the functional gametes of the adult animal. The use of avian PGCs in biobanking and producing genetically modified birds has driven research on the in vitro propagation and manipulation of these embryonic cells. In avian species, PGCs are hypothesized to be sexually undetermined at an early embryonic stage and undergo differentiation into an oocyte or spermatogonial fate dictated by extrinsic factors present in the gonad.

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Major advances in pathogen identification, treatment, vaccine development, and avian immunology have enabled the enormous expansion in global poultry production over the last 50 years. Looking forward, climate change, reduced feed, reduced water access, new avian pathogens and restrictions on the use of antimicrobials threaten to hamper further gains in poultry productivity and health. The development of novel cell culture systems, coupled with new genetic tools to investigate gene function, will aid in developing novel interventions for existing and newly emerging poultry pathogens.

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The intestinal epithelium plays a variety of roles including providing an effective physical barrier and innate immune protection against infection. Two-dimensional models of the intestinal epithelium, 2D enteroids, are a valuable resource to investigate intestinal cell biology and innate immune functions and are suitable for high throughput studies of paracellular transport and epithelial integrity. We have developed a chicken 2D enteroid model that recapitulates all major differentiated cell lineages, including enterocytes, Paneth cells, Goblet cells, enteroendocrine cells and leukocytes, and self-organises into an epithelial and mesenchymal sub-layer.

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Article Synopsis
  • In birds, males have the ZZ chromosomal configuration while females have ZW, and this study looks at how chromosomal sex affects germ cell competition and differentiation.
  • Researchers created genetically sterile layer cockerels and hens to serve as hosts for primordial germ cell transplantation using cryopreserved PGCs from Silkie broilers.
  • The results showed that sterile females with male PGCs could produce functional eggs and only male offspring, while sterile males with female PGCs produced functional sperm and viable progeny, indicating PGCs can function across sexes and have implications for poultry cryopreservation.
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Aquaculture is playing an increasingly important role in meeting global demands for seafood, particularly in low and middle income countries. Genetic improvement of aquaculture species has major untapped potential to help achieve this, with selective breeding and genome editing offering exciting avenues to expedite this process. However, limitations to these breeding and editing approaches include long generation intervals of many fish species, alongside both technical and regulatory barriers to the application of genome editing in commercial production.

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Avian species are used as model systems in research and have contributed to ground-breaking concepts in developmental biology, immunology, genetics, virology, cancer and cell biology. The chicken in particular is an important research model and an agricultural animal as a major contributor to animal protein resources for the global population. The development of genome editing methods, including CRISPR/Cas9, to mediate germline engineering of the avian genome will have important applications in biomedical, agricultural and biotechnological activities.

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  • Male birds are homogametic (ZZ) and females are heterogametic (ZW), with the DMRT1 gene on the Z chromosome being crucial for sex determination.
  • Using CRISPR-Cas9 technology, researchers created male chickens with a mutation in DMRT1, causing them to develop ovaries instead of testes, affirming that the presence of DMRT1 influences sexual development.
  • Blocking estrogen production influenced gonad development, indicating that both DMRT1 expression and estrogen synthesis are vital for proper sexual differentiation in birds.
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Poultry is the most abundant livestock species with over 60 billion chickens raised globally per year. The majority of chicken are produced from commercial flocks, however many indigenous chicken breeds play an important role in rural economies as they are well adapted to local environmental and scavenging conditions. The ability to make precise genetic changes in chicken will permit the validation of genetic variants responsible for climate adaptation and disease resilience, and the transfer of beneficial alleles between breeds.

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The human population is growing, and as a result we need to produce more food whilst reducing the impact of farming on the environment. Selective breeding and genomic selection have had a transformational impact on livestock productivity, and now transgenic and genome-editing technologies offer exciting opportunities for the production of fitter, healthier and more-productive livestock. Here, we review recent progress in the application of genome editing to farmed animal species and discuss the potential impact on our ability to produce food.

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  • Macrophages play crucial roles in development, homeostasis, and immunity, with origins traced back to the yolk sac in chick embryos, as explored in this study.
  • Research revealed that embryonic macrophages contribute about 2% to the RNA of 7-day-old chick embryos and share similar gene expression profiles with bone marrow-derived macrophages.
  • The study found that while yolk sac-derived macrophages don't persist after hatching, bone marrow-derived macrophages generate tissue macrophages in adult birds and can be increased significantly through CSF1R stimulation, leading to enhanced bone density in treated hatchlings.
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