bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spontaneous melanoma in regenerating tails of axolotls
Authors: Sheremetieva E. A. 
Published: June 2005

AbstractRelationships between neoplasia and regeneration were studied in the regenerative processes following 21 amputations through or near 8 spontaneous melanotic formations in the tails of axolotls. It was found that spontaneous melanoma can grow in the presence of regeneration, but that melanotic ingrowth into a regenerate tends to be limited to temporary “symbiotic” participation of the melanotic tissue in the development of the regenerate. It was also found that regeneration is almost always essentially normal in the presence of a spontaneous melanoma, even when the regenerate grows from the tumor itself or from a previous regenerate that is black with melanotic cells.Melanotic cells are presumably derived from normal pigment cells, and some investigators have suggested that neoplastic cells under the influence of regenerative processes may occasionally be transformed back into normal cells. The present study has provided no evidence that such a transformation ever occurs. Instead, the regenerative processes seem only to limit the neoplastic activity of melanotic cells that participate in regenerative growth. In fact, when regeneration is abnormal, melanotic cells may behave much as they do in the absence of regeneration.
The role of interstitial cells in the maintenance of hydra II. Budding
Authors: Diehl Fred A. , Burnett Allison L. 
Published: June 2005

AbstractAnimals whose interstitial cells have been selectively destroyed by nitrogen mustard continue to form new buds for nine days after mustard treatment. Buds present on parent animals at the time of mustard teatment continued to develop at the same rate as control animals; however, in most cases they failed to detach as quickly as control forms.Extensive histological examination revealed a lack of mitoses in gastrodermal digestive cells after nitrogen mustard treatment. Divisions continued in epidermal epithelio‐muscular cells for as long as 20 days. It is suggested that cell divisions in the epidermis are necessary for the initiation of the budding process and that under the present conditions the gastrodermal cells are pulled along passively into the bud outgrowth.
On the nature of the restricted differentiation‐promoting ability of transplanted Rana pipiens nuclei from differentiating endoderm cells
Authors: Subtelny Stephen 
Published: June 2005

AbstractMany diploid Rana pipiens endoderm nuclei from late gastrulae and neurulae demonstrate restrictions in their ability to promote normal development when transplanted into enucleated host eggs. To obtain information on the nature of these restrictions the nuclear descendants of 26 different endoderm nuclei from advanced embryos were injected into groups of enucleated and nucleate (non‐enucleated) haploid host eggs. In none of the 26 serial transfer experiments in which the enucleated test eggs revealed abnormal development did the nucleate test eggs show normal development. Consequently, the results demonstrated that the restrictions in differentiation‐promoting properties of transplanted diploid endoderm nuclei were dominant in the sense that they were not corrected to totipotency by combining them with “undifferentiated” haploid egg pronuclei.While ten control serial transfer experiments with blastula nuclei produced normal larvae associated with euploid chromosome complements, about half of the serial transfer experiments with nuclei from differentiating endoderm cells produced abnormal embryos associated with gross chromosome abnormalities. The other half of the serial transfer experiments analyzed for chromosome number were associated with apparently normal chromosome complements. Some produced normal diploid and triploid individuals from enucleated and nucleate host eggs respectively, demonstrating the transplanted nuclei to be totipotent. Others produced abnormal diploid and triploid embryos, the majority of which exhibited deficiencies consistent with the endodermal origin of the donor nucleus. The latter triploids did not display any further development than nucleate eggs in the experiments associated with definite gross chromosome abnormalities. In addition, variations were noted in the development of the diploid and triploid embryos and in the severity of their deficiencies which could not be ascribed to poor egg quality. They indicated differences among the donor nuclei, which may include chromosome rearrangements, but not chromosome number. Some experimental evidence has been presented which indicates that the chromosome aberrations may reflect restrictions in nuclei of differentiating endoderm cells which result in a proclivity of the donor chromosomes to replicate abnormally in host egg cytoplasm.
Differentiation of multiple molecular forms of four dehydrogenases in the teleost, Oryzias latipes, studied by disc electrophoresis
Authors: Nakano Eizo , Whiteley Arthur H. 
Published: June 2005

AbstractThe isozymic forms of four dehydrogenases, separated by disc electrophoresis in acrylamide gels, have been studied during development and in adult organs in the cyprinodontiform fish, Oryzias latipes, the medaka. Xanthine dehydrogenase appears as a single molecular form at hatching, and in the adult fish is found only in the liver and gut. Glucose‐6‐phosphate dehydrogenase is a single enzyme in early development, just before hatching two new forms appear, and after hatching all three decrease in whole larval extracts. In adults, the enzymes were found only in brain, liver, and ovary. Malate dehydrogenase increases from a single molecular form in early stages to five or six after hatching. Each adult tissue has its characteristic assemblage of isozymes. The only lactate dehydrogenase detectable before hatching is isozyme 5, and four others appear abruptly at hatching. All adult organs have one to three LDH isozymes, but isozymes 1 and 2 were found only in the retina of the eye. The abrupt change from the single isozyme 5 to the full complement occurs also in eyes of the larvae taken pre‐ and post‐hatching. Homogenates of pre‐hatching embryos do not inhibit the electrophoretic separation or reactivity of isozymes 1, 2, 3, and 4 of post‐hatching larvae. Presumably hatching triggers the appearance of the more rapidly migrating isozymes, especially strongly in the retina. On the basis of the structure of LDH isozymes in other organisms, it can be concluded that polypeptide A is present before hatching, but some restraint on the synthesis or activation of polypeptide B seems to be removed by hatching. The importance of hatching as a time of qualitative change in these four enzymes is correlated with increases in other metabolic activities at this time.
Fine structural changes in the nervous system of the regenerating hydra
Authors: Lentz Thomas L. 
Published: June 2005

AbstractThe fine structure of neurons from regenerating hydra was studied. The ganglion cells of regenerating hydra in contrast to those of normal hydra contain denser and sometimes multiple nucleoli, polyribosomes, and membrane‐bounded accumulations of dense homogeneous material which appears to be elaborated by the Golgi apparatus. During regeneration, membrane‐bounded dense granules disappear from the perikaryon of neurosecretory cells and accumulate in the processes. They are released by fusion of the vesicle membrane with the plasma membrane of the neurite. A large number of intermediate stages of differentiation of neurons from interstitial cells are present after 12 hours of regeneration. These observations support the hypothesis that neurosecretory substance released at nerve terminals plays a significant role in the regulation of growth and differentiation in the regenerating hydra.
Trophic responses to trauma in growing antlers
Authors: Bubenik Anthony B. , Pavlansky R. 
Published: June 2005

AbstractThe effects of trauma on antlers, pedicles and/or frontal bones in roe‐, red‐ and fallow‐deer during the period of antler growth were investigated. The following results were obtained: (1) antler regeneration originates from the osseous part of the pedicle or frontal bone and is not restricted to the hypothetical “Bildungssaum” or so‐called regenerative rim. (2) Unilateral trauma of a growing antler stimulates a trophic response on the control side only when the base of the pedicle, that is, the generative region of antler production, has been heavily injured. In such circumstances supernumerary and dislocated pedicles may be produced. Not infrequently the abnormality caused by unilateral trauma to the germinative bud may reappear in the next antler cycle in the same place but in a more intensified form. In general it may be found that there is a direct correlation between the trophic response to trauma and the stage of antler growth, i.e., the earlier the period of growth the more vigorous the trophic response to the trauma. Moreover, it may be that the antler cycle on the one pedicle may be accelerated or slowed down owing to trauma or other factors so far unknown. There are even cases on record where the antler on one side only may be affected differently by hormonal factors than the opposite side. All these findings have led the authors to the conclusion that each of the frontal bones, as a base for the pedicles and antlers, may have a center of antler stimulation of its own. It is assumed that in these centers (dispositions) a “pattern of antler form” is integrated. This is the only possible explanation for the memory of antler injuries on the one hand and the unilateral disturbances of antler growth on the other. It is suggested that the hormones which influence antler growth exert their effects via neural trophic centers and may thus be directed only to one antler or to a certain zone of it. Conversely, it is possible that the specific hormone may be prevented by the neural trophic centers from acting on the tissues of one antler or a certain zone of it. The site of such trophic centers is supposed to be the hypothalamus.
Studies on the incorporation of isotopically labeled nucleotides and amino acids in planaria
Authors: Best Jay Boyd , Rosenvold Robert , Souders Jacqueline , Wade Carlton 
Published: June 2005

AbstractNeither intact nor regenerating planaria incorporated any significant amount of tritiated thymidine, tritiated L‐leucine, or C14‐L‐leucine from free solution even over long periods of exposure. Tritiated thymidine was incorporated into regenerating rat liver and fed to planaria, but tritium hydrogen exchange rendered this method useless. A large incorporation of C14‐uracil and C14‐L‐leucine into planaria was obtained by growing baker's yeast in a defined medium containing the labeled compound and then feeding the acetone dried yeast to the planaria. C14 assay of the amino acid components of planaria fed on C14‐L‐leucine labeled yeast showed C14 in only the L‐leucine component and yielded a minimum estimate for protein turnover of 46% in seven weeks. Radioautographs of planaria fed on C14‐uracil labeled yeast exhibited specific incorporation into ribonucleic acid. Previous radioisotopic studies on planaria are evaluated and criticized. The amino acid composition of planarian protein was determined.
A study of strobilation in Aurelia aurita under controlled conditions
Authors: Spangenberg Dorothy Breslin 
Published: June 2005

AbstractThe maintenance of Aurelia aurita polyps in this laboratory has made possible the study of strobilation under well controlled laboratory conditions for the first time. The development of pulsing, statocysts and gastric filaments during normal strobilation occurring in artificial sea water at constant temperature was observed. Comparisons made of intact strobilae and segments cut from strobilae revealed that isolated segments of strobilae differentiated at a rate comparable to segments of intact strobilae. Furthermore, segments and pieces of segments which appeared morphologically to be polyp tissue and which exhibit no differentiation of structure were already “programmed” to become medusa tissue. Since isolated completed segments developed into ephyrae without further contributions of cells or substances from the parent it was postulated that segments of intact strobilae are, likewise, independent in their development once segments are completed.Studies of atypical strobilation resulting from simple environmental change emphasized that mechanisms that regulate segmentation are different from and probably independent of those that regulate metamorphosis of the segments into ephyrae.A discussion of the major processes involved in strobilation is presented and a close analogy to the metamorphosis of higher animals is drawn. The value of this primitive form of metamorphosis for studies of mechanisms involved in growth and differentiation is demonstrated.
Reconstitution of the spinal cord following ablation in urodele larvae
Authors: Butler Elmer G. , Ward Margery B. 
Published: June 2005

AbstractAfter ablation of 2 mm of spinal cord in the postbrachial region in larvae of Ambystoma maculatum studies were made on the reconstitution of the cord and the return of function posterior to the ablation level.Healing of the cord at anterior and posterior transection surfaces involves migration of ependymal cells to close the open central canal and movement of cells of the gray matter over the cut surface. Dilation of the central canal occurs at each transection level to form a terminal vesicle. Its wall is made up of ependyma, cells from the gray matter and an outer layer of white matter. Anterior and posterior terminal vesicles gradually increase in length bringing about a slow advance of their tips across the ablation gap, the anterior vesicle moving more rapidly than the posterior.Nerve fibers growing out from the white matter of each terminal vesicle extend across the ablation gap and eventually join the wall of the opposite vesicle. Thus are formed bridges of intracentral fibers between anterior and posterior vesicles. Broad nerve fiber bridges become the white matter of the reconstituted spinal cord. Continued advance of the terminal vesicles across the ablation region results finally in the union of the two vesicles, restoring the continuity of the spinal cord.Recovery of the use of hind limbs for walking and of trunk and tail muscles for swimming is correlated with the extent to which nerve fiber bridges have been established, but does not involve a complete fusion of terminal vesicles. All larvae which walked normally and the majority of those which swam normally possessed fiber bridges with an average diameter of at least 0.05 mm.
Production and utilization of reduced nicotinamide adenine dinucleotide phosphate in the mouse testis
Authors: Hitzeman Sister Jean Walter 
Published: June 2005

AbstractTesticular Leydig cells of BALB/c Jax mice exhibit time‐dependent patterns of nicotinamide‐adenine‐dinucleotide‐phosphate (NADP)‐linked glucose‐6‐phosphate and isocitrate dehydrogenase activity beginning five days before birth. In crude homogenates of fetal testes, glucose‐6‐phosphate dehydrogenase (G‐6‐PDH) activity is twice that found in the adult. Levels drop at birth and remain low. Isocitrate dehydrogenase activity is high during late gestation and at 10 and 60 days postpartum, but decreases in the neonatal and the prepubertal testis. Moderate prenatal NADPH‐diaphorase activity is reduced in the postpartum animal. Conversely, there is a steady increase in reduced nicotinamide‐adenine‐dinucleotide (NADH)‐diaphorase activity after birth, with adult levels being attained by the third week. Inhibition of testicular G‐6‐PDH activity by pregnenolone, dehydroepiandrosterone, and cholesterol is proportional to steroid concentration between 10−6 M and 10−4 M.The production of NADPH by isocitrate and glucose‐6‐phosphate dehydrogenases assures sufficient reducing potential for the early synthesis of androgens in fetal interstitial cells. The sustained depression in G‐6‐PDH activity found in the postpartum testis may be due in part to regulation by steroid intermediates. Hormonal precursors have no effect on isocitrate dehydrogenase which continues to supply NADPH in the postpubertal testis.
A study of induced metamorphosis in the Axolotl
Authors: Prahlad K. V. , DeLanney Louis E. 
Published: June 2005

AbstractMetamorphic changes occurred in dark and white Mexican axolotls injected with 3,3′,5‐triiodo‐L‐thyronine (T3) or DL‐thyroxine (T4), when exposed at the following ages (in days) after spawning: 3–8, 45, 62, 117, 521–541, 541‐571, at 20°C. The dosage of the hormone administered as a single injection varied from 10 μg to 100 μg. Optimum conditions in group 1 proved to be 10 μg T3 injected into the perivitelline space of six‐day‐old embryos which were subsequently released from the jelly to fresh water nine days later at 15 days of age. After two days in fresh water tissue changes were observed in this order: gills — ventral, middle, dorsal; tailtip; skin; upper eyelid. T3‐treated animals had a shorter latent period than T4 groups. There was heavy mortality in younger animals. Surviving axolotls completed metamorphosis within 25 to 35 days. Embryonic tissues, therefore, are capable of taking up the hormone and responding after the treatment is terminated, raising doubts as to the obligatory persistence of the hormone. The implications of these observations with regard to the effect of hormone at the molecular level are discussed.
Synthesis and storage of a nerve growth protein in mouse submandibular glands
Authors: Burdman Jose A. , Goldstein Milton N. 
Published: June 2005

AbstractA series of experiments were designed to determine the origin of a nerve growth promoting protein found in high concentration in the tubular portions of the submandibular glands of adult male mice. This protein is necessary for the growth and development of immature sympathetic nerve cells. The quantities of this protein can be increased in the glands of female mice to levels found in the submandibular glands of adult male mice by injecting testosterone into preadolescent or adult female mice. When testosterone was given to young mice or to adult female mice together with an antiserum prepared against the nerve growth factor (NGF), the NGF content of the testosterone‐treated mice increased in the same manner as in testosterone‐ and normal serum‐treated mice. Although antiserum against the nerve growth protein could be demonstrated in the sera of mice during the course of the entire experiment, the antiserum had no effect on the content of NGF in the submandibular glands. After the intravenous injection of NGF in large quantities, it could not be localized in liver, spleen or submandibular gland cells of the mouse as determined by fluorescent antibody techniques. The results suggested that the nerve growth promoting protein found in high concentration in the submandibular glands of adult male mice and in testosterone‐treated female mice is synthesized and stored in cells of the tubular portion of these glands.
Amino acid incorporation into protein during the molt cycle of the land crab, Gecarcinus lateralis
Authors: Skinner Dorothy M. 
Published: June 2005

AbstractThis is the first of a series of studies on protein synthesis and its control during the molt cycle of the land crab, Gecarcinus lateralis. Incorporation of valine‐1‐C14 and leucine‐1‐C14 into proteins of blood, epithelium, midgut gland, and muscle has been measured at each stage and found to reach a maximum rate in all tissues during the stages D0 through D2 of the premolt period. This period is not necessarily the period of maximum net synthesis of total protein in all tissues. Total muscle protein, in fact, is decreasing at this time: the high incorporation rate may reflect synthesis of degradative enzymes.In control experiments on possible rate limiting features in amino acid incorporation, the pool sizes of valine and leucine in plasma water were determined. These do not vary systematically with stages in the molt cycle; the relatively small fluctuations in these pools do not correlate with the larger fluctuations in incorporation rate. The sizes of these pools do not appear to be rate limiting. In conjunction with these measurements, the plasma water volume of Gecarcinus was found to be 22 ± 1.72 (S.D.) per cent of the body weight.It is also shown that the rate of penetration of amino acid from plasma water into intracellular water was not the rate limiting step in the incorporation of C14‐leucine into muscle protein. (Muscle is the tissue with the lowest incorporation rates.) Leucine penetrates muscle readily and appears to be concentrated four‐fold in muscle water relative to plasma water.
Onset of cerebral electrical activity associated with behavioral sleep and attention in the developing chick
Authors: Peters Joseph , Vonderahe Alphonse , Schmid David 
Published: June 2005

AbstractBipolar electrical recordings from the cerebral lobes of chick embryos and of freely moving chicks after hatching indicate that spontaneous electrical activity begins about the eleventh to thirteenth day of incubation, but electroencephalographic patterns characteristic of behavioral sleep or attention appear within six hours after hatching. High amplitude, slow waves, are characteristic of behavioral sleep; low amplitude, fast waves are characteristic of behavioral attention. During sleeping postures the electroencephalographic record shows brief cyclic episodes of lower voltage fast waves (paradoxical sleep) and these cycles appear more definitely as the chick grows older. When the act of waking from sleep is associated with the opening of only one eye, the lower voltage, fast waves may appear only in the contralateral lobe, while the ipsilateral lobe shows the high amplitude slow waves. In the less mature chicks, the electrical waves are slower, less regular, and of smaller amplitude, especially during sleep, furthermore the cyclic episodes of activated sleep are less distinct and the span of attention is more brief. Although chick embryos may move following tactile stimulation, the response is probably due to reflex arcs involving lower nervous centers since the cerebral lobes do not show the transition to lower voltage faster waves characteristic of attention. After hatching electroencephalographic patterns associated with sleeping postures show more conspicuous developmental changes than those associated with attention.
Gene and phenocopy: Selection experiments and tests with 6‐aminonicotinamide
Authors: Landauer Walter 
Published: June 2005

AbstractThe problems at issue concerned the epigenetic responses of chicken embryos to 6‐aminonicotinamide (6‐AN). It had been known that injected 6‐AN is responsible for malformations of the appendicular and facial skeleton (micromelia and parrot beak, respectively) and that the resulting syndrome of malformations resembles the phenotypic features of a number of independent mutations. The questions raised by our tests related to the following problems: Does heterozygosity in one of several of the micromelia‐syndrome transmitting recessive genes alter responsiveness to 6‐AN by raising the incidence of induced micromelia and parrot beak and, on the other hand, does a genotype which had been modified by selection toward low expressivity of the micromelia and parrot beak syndrome, again in heterozygous condition, result in reduced responsiveness to 6‐AN? It is concluded from the results of our test that (a) the gene mmA of the California micromelia traits promotes, in single dose, responsiveness to 6‐AN; (b) that multiple modifying genes which tend to suppress the ch/ch genotype of Lamoreux's chondrodystrophy greatly reduce, in single dose, the responsiveness of embryos to 6‐AN. It is concluded, finally, that these results satisfy for the micromelia and parrot beak syndrome, induced by 6‐aminonicotinamide, the definition of phenocopy which was implied by the hypothesis from which the present venture started, viz., that the metabolic pathways of gene and induced effect must be sufficiently related to permit interaction during development.