| 'fixed-axis' magnetic orientation by an amphibian: non-shoreward-directed compass orientation, misdirected homing or positioning a magnetite-based map detector in a consistent alignment relative to the magnetic field? | experiments were carried out to investigate the earlier prediction that prolonged exposure to long-wavelength (>500 nm) light would eliminate homing orientation by male eastern red-spotted newts notophthalmus viridescens. as in previous experiments, controls held in outdoor tanks under natural lighting conditions and tested in a visually uniform indoor arena under full-spectrum light were homeward oriented. as predicted, however, newts held under long-wavelength light and tested under either ful ... | 2002 | 12432012 |
| endosulfan affects pheromonal detection and glands in the male red-spotted newt, notophthalmus viridescens. | | 2002 | 12232734 |
| oligomerization of acidic fibroblast growth factor is not a prerequisite for its cell proliferation activity. | oligomerization of fibroblast growth factors (fgfs) induced on binding to heparin or heparan sulfate proteoglycan is considered to be crucial for receptor activation and initiation of biological responses. to gain insight into the mechanism of activation of the receptor by fgfs, in the present study we investigate the effect(s) of interaction of a heparin analog, sucrose octasulfate (sos), on the structure, stability, and biological activities of a recombinant acidic fgf from notophthalmus virid ... | 2002 | 11967362 |
| behavioral titration of a magnetic map coordinate. | spatial variation in the inclination of the geomagnetic field has been implicated in the map component of homing by eastern red-spotted newts notophthalmus viridescens. here we show that when newts are exposed to small changes in magnetic inclination, the most dramatic effects on homing orientation occur at values close to the 'home value', as predicted by the magnetic map hypothesis (phillips 1996). newts reverse the direction of homing orientation over a range of inclination of 0.5 degrees spa ... | 2002 | 11919697 |
| amyloid-like fibril formation in an all beta-barrel protein involves the formation of partially structured intermediate(s). | in the present study, we demonstrate the thermal induced amyloid formation in a beta-barrel protein, such as the acidic fibroblast growth factor from notopthalmus viridescens (nfgf-1). fibril formation in nfgf-1 is observed to occur maximally at 65 degrees c. electron microscope analysis of the thermal induced fibrils of nfgf-1 shows that they are filamentous with an average diameter of about 20 nm. x-ray diffraction analysis reveals that the thermal induced fibrils of nfgf-1 have a typical "cro ... | 2002 | 11877422 |
| vasculature in pre-blastema and nerve-dependent blastema stages of regenerating forelimbs of the adult newt, notophthalmus viridescens. | immunocytochemistry utilizing a monoclonal antibody (bv1; blood vessel 1) highly reactive to the vasculature of the adult newt showed that a developing vasculature was present during early, pre-blastema, and early-bud blastema stages of forelimb regeneration in this species. infusion of prussian blue and dii into the brachial artery further delineated the intactness of this early vasculature. finally, macroscopic observations of vascular flow underneath the apical epithelial cap (aec) and micros ... | 2002 | 11857459 |
| the role of extraocular photoreceptors in newt magnetic compass orientation: parallels between light-dependent magnetoreception and polarized light detection in vertebrates. | theoretical models implicating specialized photoreceptors in the detection of the geomagnetic field have been the impetus for studying the effects of light on magnetic compass orientation. magnetic orientation in flies, amphibians and birds has been found to be influenced by light, and in all these groups a shift of approximately 90 degrees in the direction of magnetic compass orientation has been observed under certain wavelengths and/or intensities of light. in the eastern red-spotted newt not ... | 2001 | 11511670 |
| endosulfan exposure disrupts pheromonal systems in the red-spotted newt: a mechanism for subtle effects of environmental chemicals. | because chemicals introduced into the environment by humans can affect both long-term survivorship and reproduction of amphibians, discovering the specific mechanisms through which these chemicals act may facilitate the development of plans for amphibian conservation. we investigated the amphibian pheromonal system as a potential target of common environmental chemicals. by treating female red-spotted newts, notophthalmus viridescens, to a commonly used insecticide, endosulfan, we found that the ... | 2001 | 11485864 |
| repellent function of male pheromones in the red-spotted newt. | pheromones act as attractants and sexual stimulants in most vertebrates. for example, in red-spotted newts, notophthalmus viridescens, female pheromones attract males, and male pheromones increase female receptivity. however, no studies have determined whether male vertebrates produce a pheromone that repels competing males. through a series of olfactory mate selection tests, we found that sexually motivated male red-spotted newts produce a pheromone that functions to repel other approaching mal ... | 2001 | 11351327 |
| the levels of tetrodotoxin and its analogue 6-epitetrodotoxin in the red-spotted newt, notophthalmus viridescens. | tetrodotoxin (ttx) and its analogue 6-epittx were detected in 11-12 specimens of the red-spotted newt, notophthalmus viridescens, by a post-column fluorescent-hplc system and by lc/ms in selected ion monitoring mode. ttx levels varied considerably among individuals from low (less than 0.15 microg ttx/g newt) to high concentrations (23.5 microg ttx/g newt), while 6-epittx was found to be a minor constituent in all specimens. | 2001 | 11306140 |
| letter to the editor: 1h, 13c and 15n chemical shift assignments of the acidic fibroblast growth factor from notopthalmus viridescens. | | 2000 | 10959639 |
| ichthyophonus-like infection in wild amphibians from québec, canada. | myositis associated with infection by ichthyophonus-like organisms was diagnosed in 35 of 260 (13%) wild amphibians collected in quebec, canada, from 1959 to 1964 (n = 30), and 1992 to 1999 (n = 230). infection was diagnosed in 17 green frogs rana clamitans, 9 wood frogs r. sylvatica, 4 red-spotted newts notophthalmus viridescens, 3 bullfrogs r. catesbeiana, 1 spring peeper pseudacris crucifer, and 1 pickerel frog r. palustris. the spring peeper and one of the bullfrogs were collected in 1964 fr ... | 2000 | 10843557 |
| ferromagnetic material in the eastern red-spotted newt notophthalmus viridescens | behavioral results obtained from the eastern red-spotted newt (notophthalmus viridescens) led to the suggestion of a hybrid homing system involving inputs from both a light-dependent and a non-light-dependent mechanism. to evaluate the possible role of a receptor based on biogenic magnetite in this animal, we performed magnetometry experiments on a set of newts previously used in behavioral assays. the natural remanent magnetization (nrm) carried by these newts was strong enough to be measured e ... | 1999 | 10539964 |
| regulation of prox 1 during lens regeneration. | to determine the expression pattern of prox 1 during the process of lens regeneration in the urodele notophthalmus viridescens. | 1999 | 10440259 |
| hox c6 expression during development and regeneration of forelimbs in larval notophthalmus viridescens. | a central theme concerning the epimorphic regenerative potential of urodele amphibian appendages is that limb regeneration in the adult parallels larval limb development. results of previous research have led to the suggestion that homeobox containing genes are "re-expressed" during the epimorphic regeneration of forelimbs of adult notophthalmus viridescens in patterns which retrace larval limb development. however, to date no literature exists concerning expression patterns of any homeobox cont ... | 1999 | 10370113 |
| cloning and interspecies comparisons of three newt (notophthalmus viridescens) fibroblast growth factor receptor sequences. | we report the nucleotide sequences of two fibroblast growth factor receptor (fgfr) cdnas, fgfr1 and fgfr3, from the newt species notophthalmus viridescens. these two cdna sequences and a previously published newt fgfr cdna, fgfr2, were used to derive the amino acid sequences which were then compared with their homologues from other species. this comparison shows that the intracellular tyrosine kinase domain is highly conserved across the species examined with the second half of the domain slight ... | 1997 | 9350028 |
| fibroblast growth factor receptors and regeneration of the eye lens. | if the eye lens of the adult newt, notophthalmus viridescens, is removed, a new lens will regenerate and only from the dorsal, not the ventral, iris. the source, pigmented epithelial cells, would normally no longer divide, but upon lentectomy they do re-enter the cell cycle and form lens. the cause for this capability is unknown, but the mitogenic fibroblast growth factors and their receptors may be involved. we have demonstrated that fgf receptors are present and operative in lens regeneration, ... | 1997 | 9022059 |
| organ distribution of aldehyde dehydrogenase activity in the newt, notophthalmus viridescens. | | 1997 | 9059612 |
| expression of type xii collagen by wound epithelial, mesenchymal, and ependymal cells during blastema formation in regenerating newt (notophthalmus viridescens) tails. | previously we showed that type xii collagen (col xii) is highly upregulated in the regenerating newt (notophthalmus viridescens) forelimb. here, using immunohistochemistry and in situ hybridization, we studied the pattern of expression of col xii during early stages of adult newt tail regeneration. the results show that immunoreactivity of col xii is first seen as a thin layer beneath the wound epithelium (we) at 3 days after amputation. reactivity associated with the mesenchyme becomes obvious ... | 1996 | 8921610 |
| reduction of the current of injury leaving the amputation inhibits limb regeneration in the red spotted newt. | immediately following amputation of the limb in salamanders, a strong, steady, and polarized flow of ionic current is produced by the injury. current flows in a proximodistal direction within the limb stump and is associated with a fall in electrical potential of about 50 mv/mm near the stump's end. this current is electrogenically driven by the na(+)-dependent, internally positive transcutaneous voltage of the intact skin of the limb stump. reduction of this emf, the skin's battery, by topical ... | 1996 | 8812127 |
| a laboratory classroom exercise: cell migration in cutaneous wound healing and pigmentary pattern formation in the red-spotted newt. | | 1996 | 8877464 |
| re-examining jaw regeneration in urodeles: what have we learnt? | urodele amphibians can regenerate not only their limbs and tails, but also their upper and lower jaws rather faithfully. however, relatively few studies of jaw regeneration in amphibians have been carried out, especially in recent years. it is therefore important to reexamine thoroughly this regenerating system, since the advent of sophisticated morphological techniques and the development of molecular approaches offer the promise of renewed and rapid progress in our understanding of complex dev ... | 1996 | 8877454 |
| electric field strength and epithelization in the newt (notophthalmus viridescens). | there is convincing evidence that endogenous electric fields are necessary for normal wound epithelization, but it is unclear whether normal epithelization rates can be accelerated increasing normal field strengths. although we confirmed that normal lateral fields are required for normal notophthalmus viridescens epithelization rates, significant increases in epithelization were not achieved by increasing normal field strengths with direct current. with increases of less than 50%, epithelization ... | 1996 | 8583208 |
| cloning of homoeobox sequences expressed in the intact and the regenerating newt eye. | in this report we present the sequences of four different homeoboxes cloned from the intact and regenerating eye of the newt notophthalmus viridescens. all these homeoboxes are novel for this species. | 1995 | 7607558 |
| consequences and causes of geographic variation in the body size of a keystone predator,notophthalmus viridescens. | two subspecies of the predatory aquatic salamandernotophthalmus, n. viridescens viridescens andn. v. dorsalis, differ in adult body size and geographic distribution. we tested whether experimental populations of the two predator subspecies differed in their effects on prey populations ofb. americanus, and whether observed differences in predator body size were genetic and/or environmentally induced. we compared the effects of predation by bothnotophthalmus subspecies on larvalbufo americanus by ... | 1994 | 28313881 |
| regenerative capability of upper and lower jaws in the newt. | the regenerating amphibian jaw represents an important model for studying pattern formation and the mechanisms underlying regeneration of facial structures. we have studied regeneration of upper and lower jaws in the urodele amphibian, notophthalmus viridescens, using whole mount preparations stained for bone and cartilage, scanning electron microscopy and immunocytochemistry to further characterize these regenerating systems. in addition, we have investigated whether lower jaws of adults and la ... | 1994 | 7531480 |
| effects of 3-nitrobenzothiazolo[3,2-a]quinolinium chloride (nbq) and doxorubicin on lens regeneration in the adult newt: a morphological study. | the antitumor drug 3-nitrobenzothiazolo [3,2-a] quinolinium chloride (nbq) stimulates the in vivo lens regeneration in the adult newt notophthalmus viridescens and induces a differentiated state in hl-60 leukemia cells. because the cytotoxic drug doxorubicin (adriamycin) induces differentiation of hl-60 cells in vitro we decided to compare the effect(s) of doxorubicin with nbq on lens regeneration in vivo. both drugs were injected intraperitoneally at six different schedules. morphological crite ... | 1994 | 8187978 |
| nucleotide sequences of two newt (notophthalmus viridescens) fibroblast growth factor receptor-2 variants. | the fgf receptor tyrosine kinase family consists of four members. we report the sequence of two newt (notophthalmus viridescens) fgfr2 cdnas which were isolated from a forelimb blastema cdna library and represent the newt cognates of two different isoforms of fgfr2, one homologous to bek the other to the kgfr. | 1994 | 8312364 |
| use of a specialized magnetoreception system for homing by the eastern red-spotted newt notophthalmus viridescens | laboratory experiments were carried out to investigate the effects of varying the wavelength of light on the use of an earth-strength magnetic field for shoreward orientation and for the compass component of homing. in the earlier shoreward orientation experiments, newts tested under full-spectrum and short-wavelength (i.e. 400 and 450 nm) light exhibited shoreward magnetic compass orientation. under long-wavelength (i.e. 550 and 600 nm) light, newts exhibited magnetic compass orientation that w ... | 1994 | 9317797 |
| embryonic appearance of rod opsin in the urodele amphibian eye. | notophthalmus (triturus) viridescens, a urodele amphibian (newt) common to the eastern united states, is a promising subject for developmental and regeneration studies. we have available a monoclonal antibody shown to be specific in many vertebrates for rod opsin, the membrane apoprotein of the visual pigment rhodopsin. this antibody to an n-terminal epitope, by rigorous biochemical and immunological criteria, recognizes only rod photoreceptor cells of the retina in light-and electron-microscopi ... | 1993 | 28305734 |
| the wound epithelium of regenerating limbs of pleurodeles waltl and notophthalmus viridescens: studies with mabs we3 and we4, phalloidin, and dnase 1. | the wound epithelium of regenerating limbs of the american newt, notophthalmus viridescens (nv), up-regulates a number of antigens, including those recognized by mabs we3 and we4. in the present study, we show that the we3 antigen is up-regulated in a similar fashion in the wound epithelium of the european newt, pleurodeles waltl (pw). mab we3 and we4 reactivities to secretory/transport body cell types, including integumentary glands, perineurium, endothelium, and conjunctiva, are also similar i ... | 1993 | 8409899 |
| prolactin alters the expression of integumental glycoconjugates in the red-spotted newt, notophthalmus viridescens. | prolactin (prl)-mediated changes in the texture and secretory activity of the skin in adult red-spotted newts may involve alterations in the distribution and/or expression of structural and secretory epidermal glycoconjugates. to explore this possibility, skin samples were obtained from groups of conditioned animals that had received injections of either ovine prolactin or amphibian saline over a 14-day period. glycoconjugates within the epidermis and cutaneous glands were examined by means of l ... | 1993 | 8363057 |
| expression of polysialylated neural cell adhesion molecule (psa-n-cam) in developing, adult and regenerating caudal spinal cord of the urodele amphibians. | the patterns of expression of polysialylated ("embryonic") form of neural cell adhesion molecule (psa/e-n-cam) and of all n-cam isoforms were investigated by indirect immunofluorescence and immunoblotting during the development of the central nervous system (cns) and during the regeneration of the caudal spinal cord (sc) of the amphibian urodeles pleurodeles waltl (pw) and notophthalmus viridescens (nv). in this study, a monoclonal antibody to group b meningococcus (anti-men-b) which recognizes ... | 1993 | 8398680 |
| expression of hydra head activator in newt tissues and effects on limb regeneration. | in this study, the presence of the hydra head activator (hha) neuropeptide and its influence on regenerating newt limbs (notophthalmus viridescens) was investigated. immunohistological analysis has localized the hha neuropeptide in the adult newt brain, eye, intestine, and regenerating blastema. experiments in which 9 day limb regenerates were denervated and subsequently implanted with hha-soaked beads suggest a slight progression of blastema growth compared to denervated controls. | 2013 | 8389215 |
| scanning electron microscopy of the early innervation of the wound epithelium of the amputated forelimb in the adult newt notophthalmus viridescens. | | 1993 | 8302902 |
| phosphoprotein phosphatase activity in regenerating forelimbs of adult newts, notophthalmus viridescens. | traditional signal transduction pathways appear to be operating during amphibian forelimb regeneration, as in other developing systems. a consistent picture appears to be developing that suggests that growth factors promoting proliferation during regeneration act through camp-independent mechanisms while factors that modulate differentiation and morphogenesis include signaling pathways in which camp participates. although our understanding of these pathways is far from complete, it is becoming i ... | 1993 | 8302898 |
| introduction of a retinoid reporter gene into the urodele limb blastema. | after amputation of the limb of an adult urodele amphibian at any point along the proximodistal axis, blastemal cells (the progenitor cells of the regenerate) give rise only to the missing structures. retinoic acid (ra) is able to respecify the positional identity of the blastema to a more proximal value, thus raising the possibility that the ra response system is activated during limb regeneration. cultured newt (notophthalmus viridescens) limb cells were transfected by nuclear microinjection o ... | 1992 | 1454825 |
| stimulation of dna synthesis by pdgf in the newt cardiac myocyte. | the adult newt cardiac ventricular myocyte has been successfully placed in cell culture and has been shown to undergo in vitro dna synthesis. although several growth factors have been reported to increase dna synthesis in cardiac myocytes in vitro, pdgf has not been reported to do so, but has been shown to be active in other systems. ventricles were removed from the adult red-spotted newt and were enzymatically and mechanically dissociated in a solution containing trypsin and collagenase. cells ... | 1992 | 1433320 |
| the effect of environmental ph on sodium balance in the red-spotted newt, notophthalmus viridescens. | sodium influx and efflux of the red-spotted newt, notophthalmus viridescens, at two phs were investigated in efts and adults in water and on land. the sodium efflux rate constant was not affected by ph. efflux was generally greater under aquatic than terrestrial conditions, and for efts than for adults. in an aquatic setting, both adults and efts were able to maintain sodium balance at ph 5, but exhibited net sodium loss at ph 3. sodium influx was greater in efts at ph 5 than in any other group. ... | 1992 | 1637201 |
| biogenesis of myeloid bodies in regenerating newt (notophthalmus viridescens) retinal pigment epithelium. | myeloid bodies are believed to be differentiated areas of smooth endoplasmic reticulum membranes, and they are found within the retinal pigment epithelium in a number of lower vertebrates. previous studies demonstrated a correlation between phagocytosis of outer segment disc membranes and myeloid body numbers in the retinal pigment epithelium of the newt. to test the hypothesis that myeloid bodies are directly involved in outer segment lipid metabolism and to further characterize the origin and ... | 1992 | 1628309 |
| localization of beta-endorphin-like immunoreactivity in the nervous system of the adult newt, notophthalmus viridescens. | using indirect immunofluorescence methods, we have localized for the first time in the newt, notophthalmus viridescens, beta-endorphin (beta-ep)-like immunoreactivity in the neurons of spinal ganglia (spg), spinal cord (spc), as well as in the hypothalamic region of the brain. an examination of serially sectioned spg showed that the beta-ep-positive neurons, cell bodies, and nerve fibers were distributed at all levels of spg. peripheral regions of the perikarya of beta-ep-positive spg neurons ex ... | 1992 | 1583460 |
| identification of proteins potentially involved in proximal-distal pattern formation in the regenerating forelimb of the newt. | we have used high resolution two-dimensional gel electrophoresis to identify and characterize proteins that may represent products of genes involved in establishing positional information along the proximal-distal axis of the regenerating forelimb of the newt notophthalmus viridescens. at least 24 proteins have been found whose synthesis and (or) abundance is increased in proximal (midstylopodial) regenerates relative to midzeugopodial (distal) regenerates at either of two regeneration stages, t ... | 1992 | 1497856 |
| morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, notophthalmus viridescens. | the eyelids of the newt were studied in 10 microns serial paraffin and 1-2 microns plastic sections using standard histological stains and special stains for glycoconjugates. the eyelids contain four different glands. simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. the first two are identical to cutaneous glands found elsew ... | 1992 | 1556738 |
| early innervation of skeletal muscle during tail regeneration in urodele amphibians. | the innervation pattern of skeletal muscles was studied in the normal and regenerating tail of notophthalmus viridescens. silver staining for nerve endings and histochemical localization of acetylcholinesterase (ache) were used for light microscopy. in in normal musculature, ache positive reactions were localized at the ends of the muscle fibers where they are anchored on connective tissue septa by myotendinous junctions. at this level, silver staining shows nerve terminals forming endplates. du ... | 1991 | 1744616 |
| intrinsic electric fields promote epithelization of wounds in the newt, notophthalmus viridescens. | the lateral electric fields (lfs) in the vicinity of small wounds made in hindlimb digit tip skin of notophthalmus viridescens have been measured and manipulated. healing of these wounds was assessed by crystal violet staining and by histology. paired experiments were conducted on the animals: the healing of one digit's wound was compared with healing of the contralateral digit's wound whose lf was changed from that of its contralateral wound. when currents were passed through the animal (into o ... | 1991 | 1864462 |
| tenascin localization in skin wounds of the adult newt notophthalmus viridescens. | earlier studies have shown that the extracellular matrix (ecm) protein tenascin (tn) is present between uninjured epidermal cells of urodele appendages, but is absent from most of the mesenchymally derived ecm. following appendage amputation, this distribution is reversed. tn is lost from the epidermis and appears in the ecm of the stump and the regeneration blastema. in the present study, monoclonal and polyclonal antibodies to tn were used to localize this protein immunohistochemically in limb ... | 1991 | 1718188 |
| macrophage invasion and phagocytic activity during lens regeneration from the iris epithelium in newts. | following removal of the lens through the cornea, early stages of lens regeneration from the dorsal iris of the adult newt, notophthalmus viridescens, were studied using light and electron microscopic observations on sectioned, plastic-embedded irises. specimens were fixed in karnovsky's fixative every 2 days from 0 to 12 and 15 days after lentectomy. infiltration of the iris epithelium by macrophages and their phagocytosis of melanosomes and small fragments of iris epithelial cells were observe ... | 1990 | 2392991 |
| wound currents and wound healing in the newt, notophthalmus viridescens. | wounded amphibian skin heals initially by a migration of epithelial cells from the cut edge towards the center of the wound. the density of currents leaving wounds made in notophthalmus viridescens skin was manipulated in order to determine whether electrical fields associated with these currents might have a significant role in promoting this cell migration during wound healing. wounds were made with either a needle (200 μm) or a biopsy punch (500 μm). currents leaving the wounds were measured ... | 1990 | 28305414 |
| the monoclonal antibody 22/18 recognizes a conformational change in an intermediate filament of the newt, notophthalmus viridescens, during limb regeneration. | previous work has shown that the monoclonal antibody 22/18 identifies progenitor cells (blastemal cells) which depend on the nerve for their division in the early stages of limb regeneration in the newt, notophthalmus viridescens. this antibody also reacts with cultured cells derived from the newt limb, and the intensity of immunoreactivity appears related to cell density and differentiation into myotubes. we report here that the monoclonal antibody 22/18 recognizes a polypeptide (22/18 antigen) ... | 1990 | 2317841 |
| distribution of tetrodotoxin, 6-epitetrodotoxin, and 11-deoxytetrodotoxin in newts. | tetrodotoxin was detected in all nine species of newts tested, 6-epitetrodotoxin in six species, and 11-deoxytetrodotoxin in five species. only one species lacked the analogues, thus suggesting that the analogues were common metabolites among newts. toxin levels were high in taricha granulosa and notophthalmus viridescens followed by cynops spp. distinct differences in toxin contents and profiles existed among species and tissues. | 1990 | 2339439 |
| autonomic control of heart rate in the adult, aquatic notophthalmus viridescens viridescens. | 1. we investigated the role of the autonomic nervous system in the control of the heart rate using an isolated heart preparation. 2. addition of the parasympathetic blocker, atropine, to the organ bath resulted in an increase in heart rate as expected. 3. addition of the sympathetic blocker, ergotamine, to the organ bath showed no change in the heart rate. 4. addition of the sympathetic blocker, propranolol, to the organ bath resulted in the expected decrease in heart rate. 5. both the sympathet ... | 1990 | 1980871 |
| delayed carpal ossification in notophthalmus viridescens efts: relation to the progress of mesopodial completion in newt forelimb regenerates. | the persistence of cartilage in the adult newt (notophthalmus viridescens) forelimb skeletal regenerate has recently been reported by libbon et al. it is particularly evident in the carpal group, which remains cartilaginous for at least 9 months while all other regrown skeletal parts are either ossified or ossifying. the present investigation was undertaken to determine whether delayed ossification in the adult regenerate recapitulates a pattern evident during the development of the forelimb of ... | 1989 | 2600563 |
| unequal activities of the two tilapia prolactins in the whole-animal transepithelial potential bioassay using the red eft. | the cichlid fish tilapia (oreochromis mossambicus) produces two forms of prolactin (tprl177 and tprl188) at equal rates. the primary sequences of this prolactin pair share only 69% identity. in these experiments, the whole-animal transepithelial potential (tep) in the eft stage of the red-spotted newt (notophthalmus viridescens) was measured in response to two injections totaling about 2 μg of tprl177, tprl188, ovine prl, or tilapia growth hormone (tgh), or distilled water (5 μl/injection). this ... | 1989 | 24221762 |
| flexural rigidity of marginal bands isolated from erythrocytes of the newt. | the marginal band is a bundle of microtubules residing at the periphery of nucleated erythrocytes of nonmammalian vertebrates and some invertebrates. marginal bands from erythrocytes of the newt (notopthalmus viridescens) were isolated from the cells as intact structures by treatment with detergent and either mild protease or high salt. isolated bands were subjected to mechanical testing by stretching the band between a glass microhook and a calibrated glass fiber. the deflection of the fiber pr ... | 1989 | 2715174 |
| electrical fields in the vicinity of small wounds in notophthalmus viridescens skin. | the transepithelial potential (tep) across the skin of notophthalmus viridescens hindlimb digits was measured in animals immersed in artificial pond water (apw) that was 1.5 mm in nacl, 0.06 mm in kcl, and 0.1 mm in cacl2, before and after making a wound in the digit tip. before wounding, the tep of the digit skin averaged 35.3 mv ± 5.5 mv (s.e.m.), inside positive. after wounding, the tep at locations distant from the wound approximated the tep before wounding, but, at points progressively clos ... | 1989 | 29300575 |
| spatial and temporal expression of the retinoic acid receptor in the regenerating amphibian limb. | retinoic acid is known to have dramatic effects on vertebrate limb pattern in development and regeneration, supporting a model in which a gradient of retinoic acid serves as a morphogen to differentially supply positional information to a developing limb. the discovery of a retinoic acid receptor (rar) and its homology to the steroid and thyroid hormone receptors provided a potential molecular mechanism for limb morphogenesis. one prediction of this model is that the receptor must be expressed i ... | 1989 | 2536901 |
| bulbospinal and intraspinal connections in normal and regenerated salamander spinal cord. | the salamander is the only limbed adult vertebrate which can regenerate portions of cervical, thoracic, or lumbar spinal cord. while the salamander has been a popular model for regeneration of the spinal cord, it is still not known what portions of the nervous system participate in the regeneration process. in the experiments reported here we examine the bulbospinal and intraspinal projections to the lumbar spinal cord in normal and regenerated salamanders (notophthalmus viridescens). hrp applic ... | 1989 | 2912749 |
| serotoninergic activity stimulates melanin dispersion within dermal melanophores of newts. | systemic injections of 5-hydroxytryptophan (5-htp), the precursor to serotonin, stimulates melanin dispersion within dermal melanophores of red-spotted newts (notophthalmus viridescens). injections of para-chlorophenylalanine (pcpa), an inhibitor of serotonin synthesis, inhibited melanin dispersion, and hence darkening of the skin, when newts were transferred to a dark background. the results indicate a role for serotoninergic activity in the background adaptation response in this amphibian. | 1989 | 2521686 |
| early stages of spinal ganglion formation during tail regeneration in the newt, notophthalmus viridescens. | stages in the development of sensory ganglia in the regenerating newt tail after amputation are described by taking advantage of the rostrocaudal developmental gradient of the regenerating tail. a series of ganglia, beginning at the tip of the regenerate and progressing rostrally, were examined. eight-week regenerates were used because they showed the most complete array of stages. the first recognizable ganglia appear as small clusters of cells sitting dorsally on the already established ventra ... | 1988 | 3218623 |
| appearance and regulation of an antigen associated with limb regeneration in notophthalmus viridescens. | previous reports from this laboratory have documented a cellular antigen, 22/18, associated with regeneration of forelimbs in the newt notophthalmus viridescens (kintner and brockes: nature 308:67-69, 1984; journal of embryology and experimental morphology 89:37-55, 1985; brockes: science 225:1280-1287, 1984; kintner et al.: molecular basis of neural development, 1985). the antigen is expressed at various stages of regeneration in several types of cells including schwann cells and muscle cells. ... | 1988 | 3183593 |
| nuclear characteristics of cardiac myocytes following the proliferative response to mincing of the myocardium in the adult newt, notophthalmus viridescens. | amphibian cardiac myocytes are predominantly mononucleated and have been demonstrated to respond to injury with dna synthesis and mitosis. the nature of this response with regard to nuclear number and ploidy is unclear. in this study, the apex of the newt ventricle was minced and replaced, increasing the reactive area of the wound. at 45 days after mincing following multiple injections of tritiated thymidine (2.5 microci/animal, 20 ci/mm) 15 to 20 days after mincing, three ventricular zones were ... | 1988 | 3180187 |
| culture of newt cells from different tissues and their expression of a regeneration-associated antigen. | we have established culture conditions for cells from normal limb, early limb regenerate (blastema), heart, and liver of the newt notophthalmus viridescens. whereas heart and liver cells had a relatively short life in culture, limb cells have shown no sign of senescence over more than 1 year in culture. cultured cells from all these tissues express to differing extents the regeneration-associated antigen 22/18. the antigen is intracellular and filamentous, and its expression appears to be regula ... | 1988 | 3183586 |
| treatment of brachial nerves with colchicine inhibits limb regeneration in the newt notophthalmus viridescens. | in urodele amphibians, limb regeneration is dependent on innervation and is blocked by the administration of colchicine. the objective of this experiment was to determine if colchicine blocks limb regeneration by a direct action on the blastema cells or by an indirect action on the nerves, specifically, if colchicine treatment of the brachial nerves would inhibit limb regeneration in the newt notophthalmus viridescens. colchicine was applied to the nerves by implanting a colchicine-loaded silast ... | 1988 | 3183584 |
| the effect of catecholamines and adenosine on the induction of morphological alterations and depigmentation of newt iris epithelial cells in vitro. | catecholamines and adenosine have a stimulating effect on the process of dedifferentiation of cultured iris epithelial cells (iecs) from the adult newt notophthalmus viridescens. micromolar concentrations of adrenergic ligands such as isoproterenol, norepinephrine, and epinephrine induced marked morphological alterations culminating in the stellate configuration and depigmentation of iecs. dopamine at 100 microm or higher induced the morphological response, while serotonin was ineffective. the m ... | 1988 | 2850251 |
| in vitro fusion of newt macrophages. | spontaneous formation of multinucleate giant cells is often observed in in vitro cultures of peritoneal adherent macrophages from the newts, notophthalmus viridescens and taricha granulosa (urodele amphibians). the frequency of such giant cells in these cultures is increased by the addition of phorbol myristic acetate at the initiation of the cultures. this high frequency of multinucleate cells permitted us to evaluate whether multinucleate giant cells arise by cell fusion and/or by repeated nuc ... | 1988 | 3404109 |
| laboratory studies of homing orientation in the eastern red-spotted newt, notophthalmus viridescens. | the orientation behaviour of adult male eastern red-spotted newts (notophthalmus viridescens) was studied in laboratory tests. newts were collected from ponds located 10-30 km from the laboratory, and housed in water-filled, all-glass aquaria located in a greenhouse or outdoors adjacent to the laboratory building. the aquaria were aligned on the magnetic north-south axis. newts were tested in a dry, enclosed arena in four magnetic fields: the ambient magnetic field (magnetic north at north) and ... | 1987 | 3694114 |
| eye lens regeneration and the crystallins in the adult newt, notophthalmus viridescens. | upon lens removal, the adult eastern spotted newt, notophthalmus viridescens, has the capacity to regenerate an ocular lens. crystallins, proteins characteristic of the vertebrate lens, were studied from normal and 3-month regenerated adult newt lenses. when separated by high-performance liquid chromatography (hplc) or sephadex g-200sf column chromatography, the crystallins from normal and regenerated lenses were fractionated into what appear to be the classical four groups: alpha, beta high, be ... | 1987 | 3666065 |
| effect of optic nerve denervation on lens regeneration in adult newts, triturus viridescens. | this experiment was designed to study the effect of optic nerve denervation on lens regeneration. adult newts, triturus viridescens, were divided into 4 groups: a) lentectomized newts, which served as controls, b) lentectomized newts with the optic nerve exposed and lightly palpated, c) newts with lens removed and the optic nerve cut simultaneously, and d) newts with lens removed first and optic nerve cut 7 days and 14 days later. control animals required about 21 days to produce a new lens, and ... | 1987 | 3662045 |
| longitudinal patterns of trypanosome infections in red-spotted newts. | longitudinal data on trypanosoma diemyctyli infections in individual red-spotted newts, notophthalmus viridescens, were collected over a 5-yr period. many newts (37%) retained infections throughout their adult lives and only 4.5% appeared to lose infections following their initial autumn sample. individual infection levels were higher at their first sample as compared to their second sample. newts of known age were transplanted between leech-free and leech-infested ponds. the time course of infe ... | 1987 | 3625426 |
| increased prolactin binding and morphological changes in the wound epithelium of regenerating limbs of notophthalmus viridescens. | distribution of prolactin has been examined in regenerating forelimbs from the newt notophthalmus viridescens. specific prolactin binding was demonstrated in homogenates of unamputated tissue, and of regenerating limbs at from 3 to 21 days postamputation. labeled prolactin that was injected intraperitoneally into animals with one regenerating limb accumulated in the most distal portion of the regenerate at 7 and 14 days postamputation. light-microscopic autoradiography demonstrated that labeled ... | 1987 | 3621305 |
| a monoclonal antibody detects a difference in the cellular composition of developing and regenerating limbs of newts. | we have previously described a monoclonal antibody (called 22/18) that reacts with the early blastemal cells of the regenerating limb of the newt (notophthalmus viridescens). in embryos of two newt species the antibody reacts with the epidermis, glial cells in the neural tube, the lens and cells in a restricted region of the aorta. in the developing limb bud less than 1% of the mesenchymal cells were reactive with 22/18, although most cells stained brightly with an antibody to another cytoskelet ... | 1987 | 3665773 |
| morphologic and histochemical analysis of the newt (notophthalmus viridescens) liver. | architectural arrangement, ultrastructure, and selected histochemical properties of the newt (notophthalmus viridescens) liver were examined. although hematopoietic tissue (1-4 cells thick) invested the liver, direct vascular communication between this tissue and hepatic parenchyma was not observed. the liver was intensely positive when stained with oil-red-o and periodic acid-schiff reagent and connective tissue was limited to large vascular channels and the capsule. a distinctive polarity was ... | 1987 | 3035962 |
| self-cleaving transcripts of satellite dna from the newt. | satellite 2 of the newt, notophthalmus viridescens, is a 330 bp tandemly repeated sequence scattered throughout the genome. cytoplasmic transcripts homologous to satellite 2 are found in a variety of tissues. most of the transcripts correspond precisely in length to the dna repeat unit or to whole multiples of that repeat. we show here that dimer-sized satellite 2 transcripts, synthesized with sp6 rna polymerase from a plasmid clone, undergo site-specific, self-catalyzed cleavage in vitro. the r ... | 1987 | 2433049 |
| an experimental study of population regulation in the salamander, notophthalmus viridescens dorsalis (urodela: salamandridae). | the roles of density-dependent larval survival and cannibalism of larvae as potential mechanisms of population regulation in the newt (notophthalmus viridescens dorsalis) were evaluated in laboratory and field experiments. in laboratory containers, adults cannibalized larvae and large larvae cannibalized smaller larvae. in artificial ponds, larval survival did not depend on initial larval density. no cannibalism could be demonstrated in the complex environment, although the experiment was powerf ... | 1987 | 28312257 |
| transcription of the histone loci on lampbrush chromosomes of the newt notophthalmus viridescens. | we have investigated transcription of the histone gene cluster on lampbrush chromosomes of the newt notophthalmus viridescens. clusters of the five histone genes are separated by long tracts of a dna repeat called satellite 1. previous in situ hybridization results demonstrated the presence of histone gene coding regions, intergene spacers, and flanking satellite repeats in giant transcription units on lampbrush chromosomes. these results suggested a model in which transcription initiates at his ... | 1987 | 3677922 |
| isolation of cardiac myocytes from the adult newt, notophthalmus viridescens. an electron microscopic and quantitative light microscopic analysis. | this report describes a technique which permits a high yield of viable adult cardiac myocytes from the adult newt using enzymatic separation techniques at low temperature and high enzyme concentrations. observations by light microscopy showed the isolated myocytes to have a distinctively slender morphology which consisted of a variable number of arm-like appendages radiating from the center of cells which were predominantly mononucleated. atrial myocytes were typically observed to have two to th ... | 1987 | 3629580 |
| control of blastema cell proliferation by possible interplay of calcium and cyclic nucleotides during newt limb regeneration. | the effects of the divalent cation ionophore a23187, papaverine, and chlorpromazine on the mitotic index and cyclic nucleotide levels in newt limb regeneration blastemata (notophthalmus viridescens) were assessed. the results of the experiments suggest that an intracellular increase in divalent cation (ca2+) concentration results in elevated cgmp levels, suppressed camp levels, and a corresponding increase in blastema cell proliferation. the results also suggest that the converse conditions, nam ... | 1987 | 2832230 |
| stress and changes in the blood of newts, notophthalmus viridescens, during early regeneration. | during the summers of 1984 and 1985, adult red-spotted newts, notophthalmus viridescens, were maintained in the laboratory at 23 degrees +/- 0.5 degrees c under natural photoperiods. from each of the experimental animals, the right forelimb was amputated just proximal to the elbow. control newts were not manipulated surgically. eight, 15, and 22 days after the time of amputation, equal numbers of regenerating and control animals were sacrificed, and blood smears of each individual were prepared ... | 1986 | 3806439 |
| transcription of a satellite dna in the newt. | satellite 2 is an abundant, 330-bp tandemly repeated sequence in the genome of the newt, notophthalmus viridescens. this sequence is distributed throughout the genome on each of the 11 chromosomes. both strands of satellite 2 are transcribed on the lampbrush chromosomes during oogenesis, probably as a result of readthrough from upstream structural gene promoters. in addition to these heterogeneous nuclear transcripts, satellite 2 is homologous to stable, strand-specific cytoplasmic transcripts i ... | 1986 | 3771629 |
| two magnetoreception pathways in a migratory salamander. | male eastern red-spotted newts (notophthalmus viridescens) under controlled laboratory conditions exhibit unimodal magnetic compass orientation either in a trained compass direction or in the direction of their home pond. if the vertical component of the magnetic field is inverted, newts exhibiting the simple-compass response undergo a 180 degree reversal in orientation, whereas newts orienting in the home direction are unaffected by this treatment. these results indicate that newts use an axial ... | 1986 | 3738508 |
| measurement of the extensional and flexural rigidities of a subcellular structure: marginal bands isolated from erythrocytes of the newt. | the elastic properties of marginal band, a microtubular structure isolated from the newt (notophthalmus viridescens) have been measured. bands were isolated using triton x-100 and pepsin at ph 6.8 according to the method of cohen (1978). isolated bands were manipulated with a glass microhook in a buffer-filled chamber under the microscope. single bands were stretched between the hook and a thin glass fiber. the fiber was calibrated so that the force on the band could be calculated from the displ ... | 1986 | 3747463 |
| ontogeny of cranial ossification in the eastern newt, notophthalmus viridescens (caudata: salamandridae), and its relationship to metamorphosis and neoteny. | the ontogenetic sequence of cranial osteogenesis through adulthood is described in samples of newts from completely metamorphosing and partially neotenic populations. cranial ossification proceeds in the same sequence in both samples. seven stages of cranial development are described on the basis of conspicuous events that occur during ontogeny. these include four larval stages, metamorphs, efts, and adults. neotenic adults have skulls that are metamorphosed completely and indistinguishable from ... | 1986 | 3735436 |
| magnetic compass orientation in the eastern red-spotted newt (notophthalmus viridescens). | laboratory tests were carried out to examine the orientation behavior of adult eastern red-spotted newts (notophthalmus viridescens) to earth-strength magnetic fields. groups of 30 to 40 newts were housed in water-filled, all-glass aquaria with an artificial shoreline at one end. the aquaria were located in a greenhouse or outdoors adjacent to the laboratory building, and aligned on either the magnetic north-south or east-west axis. tests were carried out in an enclosed indoor arena. newts were ... | 1986 | 3723427 |
| effects of amiloride analogues on adult notophthalmus viridescens limb stump currents. | we have previously investigated the relevance to limb regeneration of epidermally driven, na+-dependent limb stump currents by blocking epidermal na+ channels with amiloride, 3,5-diamino-6-chloro-n-(diaminomethylene)pyrazinecarboxamide. in order to reduce notophthalmus viridescens stump currents more effectively than with amiloride, we have examined six amiloride analogues. of these, only benzamil, 3,5-diamino-6-chloro-n-[(benzylamino)aminomethylene]pyrazinecarboxamide, was more effective than a ... | 1986 | 2871974 |
| monoclonal antibodies to the cells of a regenerating limb. | monoclonal antibodies were raised against differentiated cells, and blastemal cells from regenerating limbs of adult newts (notophthalmus viridescens) and screened for specific staining by immunocytochemistry. in addition to antibodies that identify muscle, schwann cells and cartilage, two reagents were specific for subpopulations of blastemal cells. one of these latter antibodies, termed 22/18, has provided new evidence about the origin of blastemal cells from schwann cells and myofibres, and a ... | 1985 | 3912459 |
| lamellar to tubular conformational changes in the endoplasmic reticulum of the retinal pigment epithelium of the newt, notophthalmus viridescens. | the retinal pigment epithelium (rpe) of the newt (notophthalmus viridescens) was examined ultrastructurally under both in-vivo and in-vitro conditions. five distinct conformations of smooth endoplasmic reticulum (ser), two lamellar and three tubular, were observed. the two lamellar conformations included myeloid bodies, which have previously been described (yorke and dickson 1984), and fenestrated ser. the latter appeared as layers of flattened or curved cisternae which were penetrated by fenest ... | 1985 | 4028144 |
| effects of temperature and bright light on myeloid bodies in the retinal pigment epithelium of the newt, notophthalmus viridescens. | myeloid bodies (mbs) are specialized regions of endoplasmic reticulum which occur in the retinal pigment epithelium of a number of vertebrate species. in the newt, notophthalmus viridescens, the effects of temperature and brief exposure to bright flashed-light on myeloid bodies have been studied. morphometric analysis has shown that in animals sampled at 06.30 h, myeloid body sectional area remained unchanged in animals maintained in the cold (1 degree c), compared with control animals at 15 deg ... | 1985 | 4028143 |
| giant readthrough transcription units at the histone loci on lampbrush chromosomes of the newt notophthalmus. | we have studied transcription at the histone loci in oocytes of the newt notophthalmus viridescens, using in situ hybridization of cloned probes to the nascent rna on lampbrush chromosome loops. clusters of the five histone coding sequences are separated by long tracts of a simple sequence dna, satellite 1. we had previously demonstrated coordinate transcription of histone genes and satellite 1 sequences. we postulated that satellite sequences were transcribed by readthrough from histone gene pr ... | 1985 | 2931253 |
| retinoic-acid-induced pattern completion in regenerating double anterior limbs of urodeles. | the effects of retinoic acid on the regeneration of double anterior lower arms in the adult newt, notophthalmus viridescens, were investigated. normally, double anterior lower arms regenerate a hypomorphic, symmetrical pattern of structures, which are distally complete; and double anterior upper arms regenerate a hypomorphic, symmetrical but distally incomplete pattern of structures. in limbs with a normal anteroposterior axis, the major effect of retinoic acid is to alter the proximodistal (pd) ... | 1984 | 6502098 |
| stump currents in regenerating salamanders and newts. | we report here that a variety of salamanders and newts from differing habitats all drive a steady ionic electric current out of the forelimb stump tip after forelimb amputation. several hours after amputation the density of this stump current ranges from about 10 to 100 microa/cm2 in most species, and declines with time. in most cases, the magnitude of the stump current is dependent on the concentration of na+ in the external medium (an artificial pondwater), suggesting that the well-known na+ - ... | 1984 | 6481332 |
| genetic structure of natural populations of the red-spotted newt, notophthalmus viridescens. | genetic variation is described at 15 loci in 2 neotenic and 12 nonneotenic populations of red-spotted newts. though high levels of genetic similarity (i = 0.990) were found among all populations, allele frequencies at six of the eight most polymorphic loci show significant heterogeneity across populations. change in allele frequencies at two of these loci (pep-2 and ldh-1) is significantly correlated with latitude. interspecific homologies are established for newt peptidases based on substrate s ... | 1984 | 6388562 |
| effects of hypophysectomy and prolactin on calcium regulation in the red-spotted newt, notophthalmus viridescens. | hypophysectomized male red-spotted newts exhibited hyponatremia but not hypocalcemia. parathyroidectomy and a combination of hypophysectomy and parathyroidectomy caused plasma calcium levels to fall, but control levels were reestablished within 12 days. injections of ovine prolactin had no effect on the plasma calcium or sodium levels of sham-operated and parathyroidectomized newts conditioned in tap water or in a 0.6% sodium chloride solution containing 10 meq calcium/liter. these data indicate ... | 1984 | 6735144 |
| the response of the atrium to direct mechanical wounding in the adult heart of the newt, notophthalmus viridescens. an electron-microscopic and autoradiographic study. | wound repair and proliferation were examined in the injured newt atrium with light- and electron-microscopic techniques including autoradiography. hearts were injured by removing a piece approximately 0.5 mm2 of the atrial wall. the five-day wound was an endothelial and mesothelial-lined blood clot bordered by a 150-micron necrotic zone. repair progressed from the periphery inward with areas of macrophage activity replaced by fibroblasts and connective tissue. the wound at 25 days consisted of a ... | 1984 | 6713487 |
| ichthyophonus-like infection in newts (notophthalmus viridescens rafinesque). | | 1984 | 6538909 |
| diurnal variations in myeloid bodies of the newt retinal pigment epithelium. | myeloid bodies (mbs) occur in the newt (notophthalmus viridescens) retinal pigment epithelium (rpe) and are similar to areas of specialized endoplasmic reticulum found in a variety of other cell types. the function of these structures is unknown, although a role in lipid metabolism has been strongly suggested. random samples from conventionally-fixed and sectioned newt rpe, obtained over a 24-hr cycle (ld 12:12), were examined by electron microscopy. myeloid bodies appear as stacks of flattened ... | 1984 | 6538116 |
| regeneration of adult newt skeletal muscle tissue in vitro. | explants and cells of forelimb muscle from adult notophthalmus viridescens were cultured for periods up to 160 days in mem-based medium supplemented with serum, hormones, and antibiotics. explants which were not minced prior to culture contained muscle fibres with healthy myonuclei and no evidence of dedifferentiation after four weeks. explants which were minced prior to culture contained degenerated muscle fibres after 1 day and no evidence of dedifferentiation after four weeks. mononucleated c ... | 1983 | 6655433 |
| a comparison of beta-endorphin levels in regenerating and nonregenerating vertebrates. | the mean plasma level of beta-endorphin in the newt, notophthalmus viridescens, as measured by radioimmunoassay, is significantly higher than the circulating levels of beta-endorphin in the anuran, rana pipiens, and in mammals (humans and mice). the newt beta-endorphin level is found to be 6-fold greater than mammalian levels and three times greater than the levels observed in rana pipiens. the high levels are maintained in the newt throughout limb regeneration. | 1983 | 6315854 |
| breeding condition, temperature, and the regulation of salt and water by pituitary hormones in the red-spotted newt, notophthalmus viridescens. | in vivo integumental transepithelial potential (tep) in the eastern red-spotted newt (notophthalmus viridescens) increases linearly with external [na+] from 0.1 to 10 mm and is anion independent. both integumental tep and osmotic permeability are higher in laboratory-conditioned (lc, terrestrial) than in breeding-condition (bc, aquatic) newts at temperatures of 5-25 degrees. prolactin (prl) treatment of lc newts decreased both tep and rate of water uptake. arginine vasotocin (avt) treatment resu ... | 1983 | 6311666 |
| annual cycle of body size and blood parameters of the aquatic adult red-spotted newt, notophthalmus viridescens. | a minimum of 20 aquatic, adult notophthalmus viridescens were captured approximately every other month during 1980 in order to investigate seasonal changes in body size and blood parameters. hemoglobin concentration, hematocrit, mean cell hemoglobin, sex, weight, snout-to-tail length, snout-to-vent length, and the presence of trypanosomes on blood smears were determined. environmental variables measured included temperature (range 5-26 degrees c), oxygen concentration (range 5.7-12.2 mg/l), and ... | 1983 | 6886660 |
| limb regeneration to digit stages occurs in well-fed adult newts after hypophysectomy. | experiments were designed to determine the maximum survival time and extent of limb regeneration of well-fed adult newts (notophthalmus viridescens) after complete hypophysectomy. adult newts were either well-fed or fasted for 3 weeks at which time hypophysectomies were performed. forelimbs were amputated 5 days posthypophysectomy. fasted hypophysectomized newts did not survive beyond 4 weeks, and limb regeneration was either absent or abortive. all of the well-fed newts survived to 3 weeks post ... | 1983 | 6842160 |