Newt limb

L. F. (1977) Bioelectricity and regeneration large currents leave the stumps of regenerating newt limbs. Proc. Natl. Acad. Sci. USA 74, 4528 532. 

Kinmer, C. R. and Brockes, J. (1984) Monoclonal antibodies identify blastemal cells derived from differentiating muscle in newt limb regeneration. Nature (London) 308,67-69. 

Mescher, A. L. (1976) Effects on adult newt limb regeneration of partial and complete skin flaps over the amputation surface. J. Exp. Zool. 195,117-128. 

Culture fluids of (1) synovial tissues involved wdth rheumatoid arthritis, (2) the skin of individuals with certain neuromuscular diseases including amyotrophic lateral sclerosis, (3) hyperplasia and inflammation of the gingivae, (4) reparative tissues of w ounds, (7) regenerative tissues of newt limb, and (6) parathormone-stimulated bone tissues have yielded increased collagenase. Histologically, proliferative vascular tissues in lesions of rheumatoid arthritis have been correlated with increased coi-lagenase production. 

Radiation adversely affects limb regeneration of amphibians, alters DNA metabolism, and increases the frequency of chromosomal aberrations and liver lesions (Table 32.25). In some species of amphibians and reptiles, as in many mammals, mortality rates after acute exposure to radiation do not stabilize within 30 days — effectively invalidating the conventional LD50 (30-day postexposure) value. In the rough-skinned newt (Taricha granulosa), for example, the minimal LD50 dose at 200 days after irradiation was 2.5 Gy, compared with 350 Gy at 30 days (Willis and... 

Newt, Notophthalmus viridescens adults, single acute exposure of 20 Gy, one limb shielded or 22 Gy, whole body, no limbs shielded Frog, Rana sp., single acute exposure Forelimb regeneration completely suppressed when limbs to be amputated were irradiated directly. Irradiated limbs had severe and protracted inflammation, with total resorption of the affected limbs in 85% of the cases. Shielded limbs subsequently amputated had delays — but not suppression — in rate of forelimb regeneration and skin graft rejection 4... 

Landesman, R.H. and W.S. Douglas. 1990. Abnormal limb regeneration in adult newts exposed to a pulsed electromagnetic field. Teratology 42 137-145. 

Maneb or mancozeb. The reader is referred to Section 2.2.1.2 for a discussion of musculoskeletal effects in humans following dermal exposure to maneb or mancozeb. Arias and Zavanella (1979) and Zavanella et al. (1984) have reported severe skeletal deformities in newts with amputated limbs that were incubated in varying concentrations of maneb. However, these experiments were performed as a model for developmental toxicity of environmental pollutants therefore, these reports are discussed fully in Section 2.2.3.6. No studies were located regarding musculoskeletal effects following dermal exposure to mancozeb in animals. 

Maneb at aqueous concentrations of 5 ppm resulted in delayed development of amputated forearms in male and female newts, with reduced melanogenesis and malformations of regenerating limbs (Arias and Zavanella 1979 Zavanella et al. 1984). However, in light of the relevant pathways of pesticide exposure in humans, the relevance of this model system to human development is not clear. 

A host of different species have been used over the past century for limb regeneration studies, including the European crested newt, Triturus cristatus, which is now a protected species. Today, however, four species predominate. One is the eastern spotted newt of North America, Notophthalmus viridescens, which is used as an adult. The adults of this species are common, adaptable to... 

Young axolotl larvae will regenerate their limbs in 2-3 wk, whereas adult newts take 2-3 mo, hut the processes they go through are identical. 

Landesman, R. H. and Copeland, K. C. (1988) Bioengineered human growth hormone supports limb regeneration in the hypophysectomized newt Notophthalmus viridescens. J. Exp. Zool. 248,247-250. 

Adult newts, or axolotls, or Pleurodeles at various stages of larval growth are usually used for these studies. The limbs are amputated, and then the animals are treated with retinoids in various ways. One method of administration is simply to add 10-60 mg retinyl palmitate (Sigma, complexed with com starch) to 1 L of water in which the animals are kept. The water turns cloudy because of the corn starch and should be changed every day. Treatment times vary from 1-14 d (22). It is also possible to treat animals in this way with tRA and other retinoids. In this case the appropriate amount of retinoid is used dissolved in DMSO (e.g., 300 iL of a 1 mg/mL solution of tRA), and this is put into the water. The retinoid immediately precipitates out, being insoluble in water, forming a yellow scum on the surface. Nevertheless, this method works perfectly well. 

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