Nikolas Morrison-Welch’s research while affiliated with California State University, Northridge and other places

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Publications (3)


NSAID-mediated cyclooxygenase inhibition disrupts ectodermal derivative formation in axolotl embryos
  • Article

March 2025

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3 Reads

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1 Citation

Differentiation

Emma J. Marshall

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Raneesh Ramarapu

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Tess A. Leathers

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[...]

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Fig. 1. (A) Concentration of AZ and TBZ in wallboard core and paper samples. (B) Linear regression of concentration of AZ and TBZ in wallboard samples (n = 8 wallboard samples). Correlation coefficient: R squared = 0.9, p < 0.0001. (C) Representative pictures of the tested wallboard samples.
Co-detection of azoxystrobin and thiabendazole fungicides in mold and mildew resistant wallboards and in children
  • Article
  • Full-text available

March 2024

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22 Reads

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1 Citation

Heliyon

The study measured the levels of azoxystrobin (AZ) and thiabendazole (TBZ) in wallboards and metabolite levels of these fungicides in children. The paper covering of wallboard samples contained a higher concentration of AZ and TBZ than the gypsum core, and similar amounts (w/w) of these two fungicides were present in the samples. These data suggest that commercial products containing a 1:1 (w/w) amount of AZ and TBZ, such as Sporgard® WB or Azo Tech™, were applied to the wallboard paper. This is the first detection of TBZ in mold-and-mildew resistant wallboards. The TBZ metabolite, 5OH-TBZ, was detected in 48% of urine samples collected from children aged 40–84 months, and was co-detected with AZ-acid, a common AZ metabolite, in 37.5% of the urine samples. The detection frequency of 5OH-TBZ was positively associated with the detection frequency of AZ-acid. These findings suggest that certain types of wallboards used in homes and commercial buildings may be a potential source of co-exposure to AZ and TBZ in humans.

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Staging series for Ambystoma mexicanum from fertilization through maturation. Stages were grouped into eight different categories: cleavage‐blastula (0–24 hours post laying, HPL), gastrula (24–54 hours HPL), neurula (54–72 hours HPL), early tailbud (72–83 hours HPL), tailbud (83–122 hours HPL), prehatched (122–342 + HPL), hatched (342 hours to 1–3 months postlaying/fertilization), and larva‐adult. Hatched larva to sexually mature adult can take up to 18 months depending on tank density. At cleavage/blastula stages, both animal and lateral views are shown. Similar to Xenopus laevis and tropicalis, Ambystoma embryos have pigment differentials on the animal and vegetal poles, the animal poles being dark and the vegetal poles light colored and filled with yolk even in leucistic animals as shown. At gastrula stages, we show both dorsal and posterior views. As gastrulation proceeds, the blastopore closes and the animals begin to neurulate. At neurula stages, we show dorsal and anterior views. After neural tube closure, the embryos begin axis elongation throughout the early tailbud and tailbud stages. At these stages, we show lateral views. The gill arches become visible during tailbud stages and further develop in the prehatch tadpoles (lateral view). At these stages, gills become more pronounced and eyes gain pigment and become visible. Prehatch embryos remain in their thick jelly coats in natural settings. In hatched tadpoles, the dorsal fin becomes more transparent, the gills branch and grow outward (lateral view). We show a dorsal view of a larva‐adult. This animal is approximately 1 year old, but is not yet fully grown or sexually mature
The amazing and anomalous axolotls as scientific models

April 2022

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249 Reads

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7 Citations

Ambystoma mexicanum (axolotl) embryos and juveniles have been used as model organisms for developmental and regenerative research for many years. This neotenic aquatic species maintains the unique capability to regenerate most, if not all, of its tissues well into adulthood. With large externally developing embryos, axolotls were one of the original model species for developmental biology. However, increased access to, and use of, organisms with sequenced and annotated genomes, such as Xenopus laevis and tropicalis and Danio rerio, reduced the prevalence of axolotls as models in embryogenesis studies. Recent sequencing of the large axolotl genome opens up new possibilities for defining the recipes that drive the formation and regeneration of tissues like the limbs and spinal cord. However, to decode the large A. mexicanum genome will take a herculean effort, community resources, and the development of novel techniques. Here, we provide an updated axolotl‐staging chart ranging from one‐cell stage to immature adult, paired with a perspective on both historical and current axolotl research that spans from their use in early studies of development to the recent cutting‐edge research, employment of transgenesis, high‐resolution imaging, and study of mechanisms deployed in regeneration.

Citations (1)


... However, delving into the genetic mechanisms governing the neotenic axolotl's regenerative processes will yield invaluable insights into its ability to keep the larval stage regenerative ability throughout life. Hopefully, these comprehensive genomic data will leverage the unique axolotl's regenerative capabilities and highlight potential clinical applications in Regenerative Medicine 108,109 . Nonetheless, a chary approach is warranted because even if humans share the axolotl's proregenerative genes, one must prove that their function has not changed, notwithstanding the ample evolutive time gap separating the two species and that human embryogenesis is a strictly regulated process. ...

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The quest for the perfect healing of human skin wounds: Promising models
The amazing and anomalous axolotls as scientific models