bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cortical integration in tetrahymena: An exercise in cytogeometry
Authors: Nanney D. L. 
Published: June 2005

AbstractThe numbers and positions of contractile vacuole pores (CVP) have been examined in strains representing ten genetically isolated groups of Tetrahymena pyriformis. In all strains the position of the CVP's moves, relative to the individual ciliary rows, as a function of the total number of ciliary rows in the cortex (Corticotype). Similarly, the number of CVP's varies in a systematic way through the corticotypic array in each strain. The development of contractile vacuole pores is shown to be regulated by gross geometrical properties of the cortex and can be described with the aid of a simple geometrical model. At least three classes of strains can be distinguished by the patterns of correlation between CVP position and corticotype. Further discriminations are possible within each class through the relationships between CVP number and corticotype. These observations aid in understanding ciliate morphogenesis and Tetrahymena taxonomy.
The response of X‐irradiated limbs of adult urodeles to autografts of normal cartilage
Authors: Eggert Ronald C. 
Published: June 2005

AbstractThe left forelimbs of 100 adult newts (Triturus viridescens) were exposed to 1,560 or 2,000 r of localized x‐irradiation; right and left forelimbs were amputated through the distal humerus. Eighty of the left irradiated forelimbs were then implanted autoplastically with cartilage taken from the dorsal cartilaginous plate of the unirradiated contralateral scapula and rendered virtually free of all cell types other than chondrocytes by subjection to manual stripping of soft tissues and perichondrium (60 cases) and manual stripping combined with brief alcohol immersion (20 cases).The results showed that the unirradiated right forelimbs regenerated normally in all cases. They also showed that the irradiated left control limbs (no implants) failed to regenerate in all cases (20). In contrast, those irradiated limbs implanted with unirradiated cartilage developed blastemata which differentiated into irregular masses of cartilage. No blastema developed following dedifferentiation of irradiated stump tissues. The blastema developed concomitantly with the breakdown of the implanted cartilage. Since these two events were separated by a time interval of two weeks, it is concluded that the blastema was formed by a direct, massive contribution of cells from the normal autograft. Further, the histologic evidence presented indicates that the majority, if not all, of the blastema cells derived from chondrocytes of scapular origin in adult newts and implanted autoplastically into irradiated limb tissue has differentiated into chondrocytes.
The influence of neural retina and lens on the development of embryonic lens vesicles in Amblystoma punctatum and Triturus viridescens
Authors: Reyer Randall W. 
Published: June 2005

AbstractEmbryonic lens vesicles from both species of salamander self‐differentiated into a small lens with fibers when implanted into either the dorsal fin or anterior chamber of the larval eye. Growth of these lenses was very slow in Amblystoma and somewhat faster in Triturus. When implanted into the pupil in place of the extirpated host lens, the embryonic lens vesicles differentiated normally and had a normal rate of growth. Lens regeneration from the host iris in Triturus was frequently inhibited by the implanted lens. A statistical analysis by the method of covariance showed that, in both species, lenses from the implants were largest in the lentectomized eyes, smaller in the vitreous chamber of eyes with intact host lens and smallest in the anterior chamber, host lens present. In Amblystoma, the growth rates, as indicated by the coefficients for linear regression, were significantly different between lenses developing in the absence of the host lens and those growing from implants into either the anterior or vitreous chambers of eyes containing the host lens. In Triturus, a significant difference was observed only between growth rates of lenses in the lentectomized eyes and in the anterior chambers, host lens present or in the dorsal fin. These results show that the neural retina stimulates growth and differentiation of embryonic lens vesicles and that the host lens retards their growth.
Analysis of some of the variables associated with the proliferative response of human lymphoid cells in culture
Authors: Wilson Darcy B. 
Published: June 2005

AbstractHuman blood leucocytes from certain individuals cultured alone — as “controls” for experiments designed to demonstrate the mutual reactivity of mixed cultures of leucocytes from different donors — revealed an intense proliferative response by the fifth day as measured by the incorporation of radioactive thymidine. Furthermore, thymidine incorporation into control leucocyte cultures from most donors was markedly elevated by the seventh day of culture. Because these high background levels tended to obscure the mutual reactivity of mixed leucocyte cultures, experiments were designed to elucidate the nature of and to circumvent these difficulties. By supplementing the growth media with human plasma, rather than calf serum, the background activity of the control cultures could be maintained at low levels without compromising the mutual reactivity of lymphocytes in the nixed cultures. One other source of variability which proved simple to control was the relative number of “contaminating” non‐lymphoid cells in the cultures. This factor was important since, in the preparation of the leucocyte suspensions with erythrocyte sedimentation procedures, the number of contaminating granulocyte cell types can be expected to vary over a wide range.Phytohemagglutinin (PHA) was used as a mitogen in experiments designed to define further some of the parameters of the lymphocyte response in vitro. When a standard number of lymphocytes — either as a “purified” suspension or as one containing significant numbers of contaminating granulocytes — was cultured with various concentrations of PHA, a dose‐dependent response was observed. Partially purified lymphocyte suspensions were only one‐half to one‐third as active as non‐purified leucocyte suspensions containing the same number of lymphocytes. This could not be attributed to a deleterious effect of PHA on purified cultures with a lower cell density since (1) the peak response of both cultures occurred with the same concentration of PHA, and (2) the maximal reactivity to PHA could be restored by increasing the granulocyte content.
The ontogeny of the multiple molecular forms of hemoglobin in the developing chick under normal and experimental conditions
Authors: Simons Jarid Allan 
Published: June 2005

AbstractA total of five molecular forms of hemoglobin appear during the development of the chick embryo. In the seven day embryo, the earliest stage studied, four of these forms are present. Hb I, preponderant in the early embryo, decreases to become a minor component at hatching; Hb II, a minor component in the early embryo, increases to become the major component at hatching; Hb III is present throughout as a minor component. Hb IV is first detectable in the nine day embryo and remains a minor component. Hb E is present as a minor component in the seven day embryo and is last found in the eleven day embryo. After hatching there is no further change in the hemoglobin pattern.In ovo oxygen deficiency and chromate retard the progressive shift from Hb I to Hb II. In vitro oxygen deficiency and chromate accelerate heme synthesis and preferentially the synthesis of Hb I.Cobalt in vivo results in a decrease in Hb I and a corresponding increase in Hb III and Hb IV. The in vivo incorporation of Fe59 indicates that the effect of cobalt is to enhance the rate of degradation of Hb I.The progressive shift from Hb I to Hb II which occurs in normal embryogenesis is discussed in terms of the control of hemoglobin synthesis at the translational level.
The effects of thiourea, photoperiod and the pineal gland on the thyroid, adrenal and reproductive organs of female hamsters
Authors: Reiter Russel J. , Hoffman Roger A. , Hester Ralph J. 
Published: June 2005

AbstractTwo experiments were conducted to test the influence of ambient light and the pineal gland on the pituitary‐thyroidal and pituitary‐gonadal axes of female golden hamsters. The results show that the thyroid glands of dark‐exposed [light:dark (LD) 1:23 in hours], goitrogen‐treated (1% aqueous thiourea as drinking fluid) animals hypertrophy less than those of similarly treated animals maintained in long daily periods of illumination (LD 16:18). Goitrogen‐induced thyroidal hypertrophy is accompanied by hypothyroidism. The hypertrophic response of the thyroid glands in either light cycle was not affected by removal of the pineal gland. Microscopically the thyroid glands of goitrogen‐treated animals kept in either long or short daily photoperiod exhibited changes normally associated with hypertrophy and concomitant hypofunction of the gland.The exposure of intact female hamsters to LD cycles of 1:23 caused a significant reduction in the weight of the uteri and adrenal glands within 35 days. Likewise, removal of the eyes led to atrophy of the same organs. Although darkness caused a variable change in ovarian weight, histological studies of ovaries from dark‐exposed and blinded animals suggested minimal hormonal output. The atrophic responses of the ovaries, uteri and adrenal glands were prevented by pinealectomy. These data suggest that darkness activates the pineal gland to secrete a substance(s) which modified pituitary‐target organ relationships.Hypothyroidism induced by the administration of thiourea to intact female hamsters in both long (LD 16:8) and short (LD 1:23) daily light cycles caused a reduction in weight of the ovaries, uteri and adrenal glands. With one exception, these responses were not altered by pineal removal. The uterine weights of the dark‐exposed hypothyroid animals that were pinealectomized were comparable to those of animals given fresh drinking water and maintained in LD cycles of 16:8 (normal controls). The relationship of the secretion of thyroid stimulating hormone to adrenocorticotrophic and gonadotrophic hormone release by the pituitary is discussed.
Regeneration of the caudal neurosecretory system in the cichlid teleost Tilapia mossambica
Authors: Fridberg Gunnar , Nishioka Richard S. , Bern Howard A. , Fleming Warren R. 
Published: June 2005

AbstractAfter total extirpation of the caudal neurosecretory system in the teleost Tilapia mossambica by ligature and removal of the caudal peduncle, a new system regenerates rapidly. The new neurosecretory cells differentiate from ependyma. A series of transitional stages between slightly modified ependymal cells and fully developed caudal neurosecretory neurons can be readily constructed. Immediately after the operation, the distal part of the remaining spinal cord undergoes degeneration, during which no traces of the caudal system can be found. Eleven days after the operation the first signs of the new system appear, and after three weeks a potentially functional, although much reduced, system has developed, the elements of which are detectable with the electron microscope. After 5–6 months, an extensive system has regenerated; however, the neurohemal area equivalent to the normal urophysis is contained within the spinal cord. There is strong cytologic evidence for a considerable release of elementary neurosecretory granules into the cerebrospinal fluid in the regenerating and regenerated system, possibly by several different mechanisms. Prominent tubular reticula occur in the distal (preterminal) parts of the neurosecretory axons, and the possibility of local axonal production of vesicles and granules is strongly supported. Signs of secretion into the central canal and of distal production of neurosecretory material are also present in normal Tilapia, but both phenomena are much more strikingly demonstrated in regenerating systems.
On the role of metal cations in cellular adhesion: Effect on cell surface charge
Authors: Armstrong Peter B. 
Published: June 2005

AbstractAn examination has been made of the hypothesis that the role of divalent cations in promoting reaggregation of dissociated cells is principally to reduce the negative electrostatic charge at the cell surface. This hypothesis would suggest that cells in the presence of different divalent cations would reaggregate at identical rates if the concentrations of the different cations were so adjusted that in all cases the cells possess the same charge. This expectation has not been fulfilled. Magnesium ion was most effective in promoting reaggregation, calcium somewhat less so, and strontium and barium had little or no effect.
Induction of altered patterns of cortical morphogenesis and inheritance in Paramecium aurelia
Authors: Wille John J. 
Published: June 2005

AbstractThe effect of phenethyl alcohol (PEA) on cortical morphogenesis in Paramecium aurelia in relation to the fission cycle was investigated by the method of sister cell analysis. PEA interferes with cortical morphogenesis by suppressing the formation of cortical units, presumably by the inhibition of kinetosome production. The action of PEA at different timed stages during the fission cycle shows that there are series of “transition points” beyond which PEA no longer has any effect on cell division, but still blocks cortical unit formation, while at a later time, both cell division and cortical morphogenesis are unaffected. Incompletely divided cells, “chains,” lacking oral membranelles are produced after prolonged PEA treatment. The specific inhibition of oral membranelle formation is shown by the effect of PEA on oral morphogenesis during fertilization and reorganization in the absence of cell division. The gullet condition following PEA‐treatment during conjugation is restored to normal through successive cell generations, except for those cells lacking oral membranelles. The results indicate that chemical modification of the cortex can result in persistent changes in the pattern of cortical organization.
Origin and development of retinal melanin in Amblystoma punctatum devoid of ovarian pigment
Authors: Piatt Jean 
Published: June 2005

AbstractThis report is concerned with the origin and elaboration of melanin in the retinal epithelium of Amblystoma punctatum. The animals used in this study developed from a single clutch of unpigmented eggs. The tapetum of such animals is devoid of ovarian pigment and, consequently, the initial formation of melanin can be readily followed. Specifically examined is the possibility of active involvement of melanocytes in the formation of tapetal pigment.Eyes were transplanted from embryos at stage 32+ into the gill region and ventral flank of embryos at stage 28. Data were obtained concerning the initial appearance of melanin and its subsequent elaboration in the tapetum of the grafts correlated with the presence or absence of melanocytes in the immediate vicinity.Melanin first appears in the flank grafts two to three days before melanocytes reach the area. Sequence of melanin elaboration in both types of graft follows more closely that of the donor animals than that of the less advanced hosts. Melanin always appears first in the anterior portion of both grafts and intact eyes, despite the fact that melanocytes are just as closely associated with the posterior pole of the eyes. It is concluded that melanin production is an intrinsic property of the retinal epithelium in Amblystoma.
Insect neurometamorphosis. III. Nerve cord shortening in a moth, galleria mellonella (L.), may be accomplished by humoral potentiation of neuroglial motility
Authors: Pipa Rudolph L. 
Published: June 2005

AbstractNerve cord segments were removed from last stage larvae and pharate pupae and transplanted into recipients of known developmental age. When transplanted into larvae the connectives shortened maximally in near‐synchrony with their host's counterpart; in both, potentiation began during early pupal development, and was completed 1.5–2.5 days after ecdysis. Histological comparisons revealed metamorphic changes in transplants, changes which paralleled those normally occurring in situ. Shortening of transplanted segments is not adventitious, and it would seem that shortening of the transplant and the host's counterpart are manifestations of the same phenomenon.Larval connectives transplanted into pupae younger than two days shorten completely; those transplanted into pupae aged two days or older, or into adults, do not. Actively shortening connectives shorten completely when transplanted into pupae two days old, or into younger pupae, but not when transplanted into larvae, or into pupae three or more days old. This affirms a critical period in the early pupa when activation is maximal. The nature and source of the potentiating factors are unknown, but most likely they are blood‐borne.Connectives with cauterized ganglia will shorten even though axon degeneration is pronounced. This shortening, too, is potentiated during the critical period. The hypothesis is advanced that humoral factors may be potentiating shortening by activating neuroglial motility.Connectives which shorten slightly in situ will shorten entirely if transplanted into hosts in the critical period. The inhibition removed by the operation may be mechanical, since connectives which shorten in situ are located in body segments which also shorten.
On the similar orientation of fibrillar structures and rows of esterolytic invaginations in plasmodia of the slime mold, Physarum confertum Macbr.
Authors: Bauer L. G. 
Published: June 2005

AbstractThe localization of thiolacetic acid esterase activity in plasmodia of the slime mold, Physarum confertum Macbr., permitted the visualization of a system of esterolytic invaginations of the plasma membrane which appeared closely related to the arrangement of fibrillar structures. Fibrils running perpendicularly to the long axis of tubes and channels of the conducting system were found to be attached to relatively large lateral infoldings, while rows of smaller invaginations seemed to follow the course taken by the fibrils. In living and fixed specimens, constrictions in the diameter of tubes and channels were observed at the level of fibrils and linearly arranged rows of infoldings. These findings suggest that esterase‐positive infoldings may result from the contraction of fibrillar structures which are attached to the plasma membrane at multiple points along their length.
Studies on the physiology and genetics of the rotifer, Asplanchna. III. Results of outcrossing, selfing, and selection
Authors: Birky C. W. 
Published: June 2005

AbstractSympatric populations of Asplanchna brightwelli and A. girodi do not hybridize, so that these two morphological species represent distinct biological species or syngens. Populations of A. brightwelli from Tennessee and Indiana may be crossed to give viable F1, F2, and backcross generations. These two widely separated populations may thus be assigned to a single biological species. A program of repeated selfing with selection for high clonal viability has been carried out with A. brightwelli. Clonal viability declined with the first selfing, then rose with succeeding generations of selfing and selection, to or above the viability of clones obtained by inbreeding within the parental mixed stock. Selfing also led to an increase in the homogeneity of the growth rates of groups of sibling clones obtained by selfing, suggesting increased homozygosity in the selfed, selected lines. The results of the selfing and selection experiments suggest that wild stocks of Asplanchna are heterozygous for a number of recessive detrimental and lethal genes affecting the growth rate and viability of clones. The heterozygosity of the natural populations, together with the failure of geographically isolated populations of a morphological species to become reproductively isolated, suggests that these rotifers are not extreme inbreeders. It is suggested that the maintenance of recessive detrimentals in these rotifers, in which the males are haploid, may indicate that the phenotype of a male is determined to a large extent by the genotype of its mother. Such maternal effects would protect detrimentals from selection in the male offspring of heterozygous females.
Studies on the mechanism of implant‐induced supernumerary limb formation in urodeles. I. The histology of supernumerary limb formation in the adult newt, triturus viridescens
Authors: Carlson Bruce M. 
Published: June 2005

AbstractSupernumerary structures were formed in adult Triturus forelimbs following subcutaneous implantation of pieces of frog kidney. The gross and microscopic events in supernumerary limb formation were described in this paper. The first few days after implantation comprise a stage of wound healing and phagocytosis, the latter by both the epidermis and inflammatory cells of the host. Following this the tubular portions of the implant degenerate. During the height of this degeneration, the first dedifferentiated cells of the host are seen. These cells increase in number and gather around a central focus to form a blastema. From the blastema, first cartilage and then muscle differentiate, and elongation proceeds concomitantly with this differentiation. The final result of the kidney implant may be no growth at all, periosteal chondrification not preceded by a blastema or a true supernumerary structure ranging in complexity from a cartilaginous nodule to a fully developed supernumerary limb. The results of this experiment indicate that aside from the initial stimulus and the ultimate degree of morphogenetic complexity attained, the development of a supernumerary structure is very similar to the regeneration of an amputated limb.
Studies on the mechanism of implant‐induced supernumerary limb formation in urodeles. II. The effect of heat‐treatment, lyophilization and homogenization on the inductive capacity of frog kidney
Authors: Carlson Bruce M. , Morgan Charles F. 
Published: June 2005

AbstractIn experiments designed to test the effect of physical manipulations upon the ability of frog kidney implants to induce supernumerary limbs in Triturus viridescens, kidney tissue from adult Rana pipiens was treated by boiling, lyophilization and homogenization. Normal kidney induces supernumerary growth in over 90% of cases. Boiling at 100°C for ten minutes destroyed the ability of the kidney implant to stimulate supernumerary growth. Lyophilization did not affect the inductive capacity of the implant. Normal percentages of accessory growth were observed after multiple injections of frog kidney homogenates. It was concluded that some chemical agent(s) present in frog kidney is responsible for the inductive effect.
Genetic and experimental studies on a lethal trait (“Short Toes”) in the Mexican axolotl (Ambystoma mexicanum)
Authors: Humphrey R. R. 
Published: June 2005

AbstractA recessive lethal factor (s) discovered in the Mexican axolotl induces (1) reduction in length of limbs and number of phalanges, (2) failure of complete development of Mullerian ducts, and (3) renal pathology and dysfunction leading to death.Larvae homozygous for s, in parabiosis with normal animals, show no improvement in length of limbs or number of phalanges. Transplants of the forelimb area between normal and s/s embryos produce limbs of donor type. The character of the limbs in the s/s thus appears independent of nutritional or hormonal influences.The Mullerian ducts of s/s reared as parabionts with normal animals remain incomplete. The duct derived from a pronephric transplant from an s/s into a normal embryo attains full length, however, as does the duct from the reciprocal type of transplant. Probably intrinsic factors in duct epithelium and related stroma combine in s/s larvae to limit duct growth.Death of affected animals usually occurs before they are one year of age. Although some attain sexual maturity, none has reproduced.Gene s was probably carried by some of the white axolotls imported from Cracow by the Wistar Institute in the early 1930's. No linkage with other genes has been demonstrated.