bluuebunny/crossref_metadata_2025 huggingface dataset:
Renal excretion of chlorphenol red and related organic acids in the intact flounder Pseudopleuronectes americanus
Authors: Mackenzie Duncan D. S. , Maack Thomas , Kinter William B.
Published: June 2005

Renal clearance experiments were performed on unanesthetized winter flounder from which bladder urine was collected continuously and caudal vein blood was sampled periodically; renal tissue was also obtained terminally for comparison of test organic acid content in vivo and after incubation in vitro. Urine flow rates and inulin U/P (urine to plasma concentration) ratios were relatively constant for a given fish and averaged 1.0 ml/hr × kg fish and 2.6, respectively. In contrast, U/P ratios for all three test acids cycled from minima of near 100 to maxima of over 1000 roughly every 24 hr when plasma concentrations of unbound acid were below 1 μM; correction of plasma protein binding was required in the case of chlorphenol red, but not PAH or Diodrast. Both in vivo and in vitro the organic acid content of renal tissue was intermediate between plasma and urine concentrations. These results demonstrate that kidneys of intact flounder exhibit the remarkable concentrative capacity for exogenous organic acids previously observed with isolated tubules and suggest that the tubular urine concentration is established in two steps by cell transport first at the peritubular and second at the luminal membrane. The anterior kidney position and the magnitude of maximal PAH and Diodrast clearances, about 1000 ml/hr × kg flounder, are consistent with most of the cardiac output returning to the heart through the renal portal circulation; a regulatory shunt bypassing the peritubular capillaries is proposed to explain cycling of organic acid clearances to minimal values.
Prolactin and substrate stimulation of locomotor activity in adult tiger salamanders (Ambystoma tigrinum)
Authors: Duvall David , Norris David O.
Published: June 2005

Groups of adult tiger salamanders were treated with either prolactin or saline and were maintained between behavioral observation on either a moist pea gravel substrate or in water. During 60‐minute observation periods, all animals in a group were placed together in moisture‐gradient apparati, and locomotor activity scores and substrate preferences were recorded and analyzed. Prolactin or saline and substrate type exerted no effects on eventual substrate preference. However, animals in both substrate groups treated with prolactin displayed greater activity than either group treated with saline. The group of salamanders treated with prolactin and held between behavioral observations on moist gravel displayed significantly more activity than animals in any other group. These results suggest that prolactin‐stimulated locomotion represents a behavioral component of a “second metamorphosis” event in tiger salamanders.
Ultrastructural study of concanavalin‐A binding to the surface of preimplantation mouse embryos
Authors: Konwinski Marian , Vorbrodt Andrzej , Solter Davor , Koprowski Hilary
Published: June 2005

Receptors for Con‐A were labelled (using the peroxidasediaminobenzidine technique) on the plasma membrane of unfertilized and fertilized mouse eggs, cleavage stage embryos, trophoblast and inner cell mass (ICM) of the blastocyst. Embryos were exposed to Con‐A concentrations of 10 μg/ml, 50 μg/ml, or 1,000 μg/ml and the lowest concentration was observed to be the most suitable for discerning differeces between stages of embryonic development.

On the surface of unfertilized and fertilized eggs and 2‐cell embryos, reaction product appeared as a thin, discontinuous layer. The surface of 4‐ and 16‐cell stage embryos had a thicker, continuous, although non‐uniform, layer of the reaction product. On the surface of the cells of the late morula, and on the trophoblastic cells of the blastocyst, clustering of reaction product, was observed. Cells of ICM of intact blastocyst were free of the reaction product, showing that either Con‐A and/or peroxidase cannot penetrate tight junctions between trophoblastic cells. Reaction product in the form of a thin, uniform layer covered the free surface of the cells of the ICM after they had been isolated (using immunosurgery) and exposed to 50 μ/ml of Con‐A.

The amount and distribution of Con‐A receptors is discussed, along with their redistribution and mobility in relation to the agglutinability of preimplantation mouse embryos.
The phosphoenol‐pyruvate branchpoint in adult Hymenolepis diminuta (cestoda): A study of pyruvate kinase and phosphoenol‐pyruvate carboxykinase
Authors: Moon T. W. , Mustafa T. , Hulbert W. C. , Podesta R. B. , Mettrick D. F.
Published: June 2005

The properties of pyruvate kinase (PK) and phosphoenol pyruvate carboxykinase (PEP CK), two enzymes that determine the preferrential accumulation of either succinate or lactate as endproducts of carbohydrate metabolism, are described in adult Hymenolepis diminuta. PK activity at Vmax and Km levels of PEP was unaffected by ATP, alanine, FDP4, or H+ ions, but was inhibited by 50% at 6.3 mM L‐lactate and 30 mM HCO3−. The addition of 30 mM HCO3− increased the Km (PEP) by 6‐fold but did not alter the Vmax. The inhibition of PK by HCO3− cannot be explained entirely by an effect of ionic strength, but probably represents a specific modulator‐enzyme interaction. Under similar conditions PEP CK was maximally activated. Although L‐lactate inhibited PEP CK (Ki(lac) = 1.8 mM), this effector may play a minor role in regulation of PEP flux. These results implicate the poise of the HCO3− :CO2 system as a major determiner of endproduct accumulation in H. diminuta.
Is the activated spermatozoon really capacitated?
Authors: Barros Claudio , Berrios Miguel
Published: June 2005

A culture medium (7N) consisting only of salts and devoid of any macromolecule was prepared to test its effect upon survival, activation and acrosome reaction of golden hamster spermatozoa. Incubation of spermatozoa in medium 7N allowed a temporal separation of activation and acrosome reaction. Over seventy per cent of spermatozoa were activated after four hours at 37°C while the acrosome reaction remained very low (8%). Activated spermatozoa with intact acrosomes were incubated with zona‐free hamster oocytes at 37°C for one to two hours. When these oocytes were examined with the electron microscope it was found that the spermatozoa were closely bound to the egg plasma membrane, mainly by the plasma membrane overlying the acrosome, but in no instance had the gamete membranes fused. Prolonged incubation resulted in an engulfment of the sperm by the oocyte in a phagocytic manner. The experimental evidence would indicate that an activated spermatozoon is not capacitated since it cannot fertilize oocytes.
Observations on the fertilization block between Xenopus borealis and Xenopus laevis laevis
Authors: Brun R. , Kobel H. R.
Published: June 2005

Eggs of Xenopus borealis usually can not be fertilized by sperm of Xenopus laevis laevis, while laevis eggs do not exhibit such a fertilization block to borealis sperm. But if borealis eggs obtained from the body cavity and thus lacking jelly are enrobed with laevis jelly following transfer to the body cavity of laevis and subsequent passage through the oviduct, fertilization with laevis sperm can occur. Alternatively, laevis eggs enrobed with borealis jelly can not be usually fertilized with sperm of their own species but are still fertilized by borealis sperm. Evidence is presented that suggests that laevis sperm can not penetrate the innermost jelly layer of borealis eggs.
Polymorphism and polyploidy in the rotifer Asplanchna sieboldi: Relative nuclear DNA contents in tissues of saccate and campanulate females
Authors: Jones Philip A. , Gilbert John J.
Published: June 2005

The relative DNA content of nuclei from saccate and campanulate females of A. sieboldi was measured cytophotometrically. Mitotic figures from embryonic tissues of both morphotypes had similar DNA contents, indicating that both are diploid. Adult tissues were mixoploid with nuclear DNA levels characteristic of replications of the entire genome. The yolk gland nuclei showed the highest levels of ploidy (36‐ to 300‐ploid), with the greater values being restricted to the terminal regions. The gastric gland nuclei showed intermediate levels (2‐ to 50‐ploid). Oocytes were diploid and arrested in G2.
The order of tooth development and eruption in the rainbow trout (Salmo gairdneri)
Authors: Berkovitz B. K. B.
Published: June 2005

The ontogeny of the dentition of the rainbow trout (Salmo gairdneri) has been studied by examining serial sections of 27 hatchlings ranging in age from the day of hatching to 34 days after. By the end of the first month after hatching, the dentition of the rainbow trout consists of about 12 teeth. Though the teeth develop in rapid succession, it was possible to determine their precise sequence of development. The study showed that the teeth develop in an alternate sequence, the teeth occupying the odd‐numbered tooth positions arising first; the first tooth to develop occupied the third tooth position. The order of eruption reflected the order of initial tooth development. Occasional variations in the sequence of development were encountered. The time between initiation of these first teeth and their appearance within the oral cavity is of the order of 12 days. The teeth remain erupted for about two weeks before they are exfoliated.
Homozygous mouse embryos produced by microsurgery
Authors: Markert Clement L. , Petters Robert M.
Published: June 2005

Homozygous mouse blastocysts have been produced following microsurgical removal of one pronucleus from the fertilized egg, diploidization in cytochalasin B, and culture in vitro. This combination of techniques should greatly shorten the time required to obtain homozygous strains of mice.
Cell interactions required for transdetermination in the imaginal leg disc of Drosophila melanogaster
Authors: Chihara Carol J. , Gerhart John C. , Lee Li‐Wen
Published: June 2005

Male foreleg imaginal discs from late third instar larvae were cut along radii as designated on a clockface, and the sectors were tested separately for their ability to transdetermine to wing and to regenerate leg structures. The frequency of transdetermination depended strongly on the position of the cuts: discs cut into 12‐6 and 6–12 fragments or into 12‐9 and 9–12 fragments gave wing frequently, derived from the 6–12 and 9–12 fragments, respectively; whereas discs cut into 6–11 and 11‐6 fragments transdetermined rarely. Regeneration showed a different pattern, with the 6–12, 9–12 and 6–11 fragments regenerating frequently. Thus, the 6–11 fragments regenerated but did not transdetermine, indicating the separability of these two phenomena. The 12‐6 and 11‐6 fragments could be induced to transdetermine more frequently by implanting each in combination with a 6–11 piece. These results suggest that disc cells must interact with other cells not normally their neighbors in order to transdetermine, and that the transdetermining cells may be located in the upper central region of the disc.
Observations on the cortical reaction in eggs of Brachydanio rerio as seen with the scanning electron microscope
Authors: Hart Nathan H. , Yu Sui‐Foh , Greenhut Victor A.
Published: June 2005

Ripe eggs of Brachydanio rerio were fixed at selected intervals of time after activation, dechorionated, and prepared by standard techniques for viewing under the scanning electron microscope (SEM). The surfaces of eggs fixed two to four minutes after activation show all stages in the activation and extrusion of the cortical granules. At least four morphologically distinct and temporally sequential stages for the cortical granule reaction are observed with the SEM. These include the elevation of the cortical granule above the egg surface, the extrusion of the contents of the cortical granule, the transient participation of the limiting membrane of the cortical granule in egg surface membrane formation, and replacement of the granule limiting membrane by the egg plasma membrane. We propose that a consequence of egg activation is the retrieval of the cortical granule membrane.
Preliminary evidence for the intracellular localization of luteinizing hormones in mammalian oocytes
Authors: Jagiello Georgiana , Ducayen Mercedes B.
Published: June 2005

Preliminary autoradiographic and immunofluorescent evidence is presented which suggests the localization of hLHβ, hCG and oLH within the oocytes of several mammalian species. Specificity of the response is supported by negative observations in the presence of cold hormone or antibodies to other proteins. The mechanism of action of these gonadotrophins in such a site remains to be defined.
Involvement of two carbohydrate‐containing components in the binding of uncapacitated spermatozoa to eggs of the golden hamster in vitro
Authors: Hartmann John F. , Hutchison Cameron F.
Published: June 2005

The mechanism by which uncapacitated epididymal sperm bind to eggs of the golden hamster in vitro has been investigated for the eventual purpose of understanding the nature of the molecular changes that the sperm surface undergoes during capacitation. It was possible to remove bound uncapacitated sperm by washing in medium supplemented with glucuronic acid; other sugars were partially effective or completely ineffective. Pretreatment of sperm with β glucuronidase prevented binding, suggesting that glucuronic acid on the sperm head is involved in binding. If sperm were allowed to bind for 25 minutes, then medium supplemented with glucuronic acid was no longer effective in removing sperm, indicating the nature of binding changes with time.

Binding of uncapacitated sperm could also be prevented by removing the epididymal supernatant introduced with the sperm, but it did occur if the eggs were first treated with a purified pronase digest of epididymal supernatant. The active material appears to be oligosaccharide, very likely the carbohydrate portion of epididymal glycoproteins. Glucuronic acid could not be detected in the active fractions of the epididymal supernatant digest suggesting that the binding of uncapacitated sperm depends upon the cooperation of sperm head glucuronic acid and soluble oligosaccharide. The requirement for the soluble factor was not specific, since several glycopeptide fractions derived from pronase digests of either epididymal supernatant or the plasma glycoprotein fetuin caused uncapacitated golden hamster sperm lacking the original supernatant, to bind. However, such sperm would not bind to mouse eggs treated with these fractions.
Cardiac mutant salamanders: Evidence for heart induction
Authors: Kulikowski Robert R. , Manasek Francis J.
Published: June 2005

Homozygosity for gene c in Ambystoma mexicanum results in no detectable heartbeat in situ. Alteration of the cardiac environment through organ culture results in rapid initiation of spontaneous heartbeat, indicating that absence of cardiac function in situ is not the result of failure of embryonic induction.
The effect of light on forelimb regeneration in the newt
Authors: Maier C. Eberhardt , Singer Marcus
Published: June 2005

The forelimb of the newt, Triturus (Notophthalamus) viridescens, was bilaterally amputated and the animals subjected to different photoperiods during the period of regeneration, namely (1) continuous light, (2) 15 hours of light/day and (3) total darkness. Animals exposed to continuous light reached the palette regeneration stage four to five days before those kept in total darkness with the 15 hours of light/day animals being intermediate. The difference in regeneration rate was first evident in the moderate early stage (blastema accumulation stage); it then increased during subsequent stages and the difference persisted during the observation period. In an attempt to determine whether the retina was the receptor of light affected, some animals were blinded at the time of amputation and subjected to continuous light. Their rate of regeneration was similar to sighted animals subjected to continuous light but greater than sighted animals in total darkness. The pineal is discussed as the likely mediator of the photo effect.
Orientation and behavior of epithelial cell muscle processes during Hydra budding
Authors: Otto Joann J.
Published: June 2005

The reorientation of the muscle processes of the ectodermal epithelial cells in Hydra attenuata has been examined during bud morphogenesis and in grafts inserted at right angles to their original orientation. The muscle processes were observed in histological preparations after staining with Mallory's Triple Stain and, in freshly fixed hydra, with polarization microscopy.

Since the bud forms as an outpocketing from the parent, the ectodermal muscle processes, which run longitudinally, must reorient at some stage in order to be in the proper orientation on the bud. During the early stages of bud development, the reorientation of the ectodermal muscle processes is a passive result of the deformation of the parental tissue. Later, active reorientation occurs.

The means by which muscle processes are able to reorient was studied further in rectangular grafts placed at right angles to their original orientation. In these grafts, muscle processes become aligned with those of the host in two ways: (1) in groups through the rotation of the whole graft or (2) individually, probably by retracting and then reextending in the new direction.
Oxygen consumption and activity in salamanders: Effect of body size and lunglessness
Authors: Feder Martin E.
Published: June 2005

Oxygen consumption during and after two minutes of strenuous activity was measured at 25°C in three groups of salamanders: temperate zone lunged, temperate zone lungless, and neotropical lungless. No increase in oxygen consumption was detected during two minutes of activity. There were significant differences among the three groups of salamanders in the effect of body size on maximum oxygen consumption and aerobic scope. Small lungless salamanders consumed more oxygen than small lunged salamanders; however, large lunged salamanders consumed more oxygen than large lungless salamanders. Neotropical lungless salamanders showed lower maximum oxygen consumption than temperate zone lungless salamanders, but the effect of body size was similar in these two groups. Small salamanders, both lunged and lungless, pay off oxygen debt at the same relative rate as indicated by percent of scope. Large lungless salamanders pay off debt at a slower rate than large lunged salamanders. Maximum oxygen consumption, aerobic scope, and payoff of oxygen debt are correlated with total respiratory surface area, especially at large sizes. Large lungless salamanders show a reduced capacity to transport oxygen following activity.
Insect cellular differentiation. I. Redifferentiation of the adult labial glands of Manduca sexta (lepidoptera)
Authors: Jones James E. , Hakim Raziel S.
Published: June 2005

With the exception of a few primitive ephemeropterans, winged insects do not normally molt as adults, although they can molt under appropriate hormonal conditions. We investigated this supernumerary molt process by taking adult labial glands (from Manduca sexta), cutting them into fragments of a single cell type, implanting them into individual freshly molted pupae, and then recovering them from pharate adult and adult hosts. The appearance and function of these fragments were compared to those of normally metamorphosing glands. Based on these criteria: (1) the supernumerary adult molt involved cellular deand re‐differentiation and (2) no transdifferentiation occurred, between the separate adult gland cell types.
Tubulin and microtubule‐like structures in mammalian acrosomes
Authors: Stambaugh R. , Smith M.
Published: June 2005

Immunofluorescence and electron microscopy were used to demonstrate the presence of tubulin and microtubule‐like structures in rabbit and rhesus monkey sperm acrosomes. The distribution of tubulin within the acrosome appeared similar to the distribution of proteolytic activity, suggesting an association of proteinase with these structures. Electron microscopy of rhesus monkey sperm incubated in vitro demonstrated a progressive condensation of the acrosomal matrix into microtubule‐like structures. A system of this type could explain the linear patterns of silver‐proteinate staining in the penetration tunnel through the zona pellucida.
Glutamate dehydrogenase from coelenterates NADP specific
Authors: Hoffmann Richard J. , Bishop Stephen H. , Sassaman Clay
Published: June 2005

Glutamate dehydrogenases detected in tissue extracts of a broad sample of coelenterate species all require NADP(H) as a co‐substrate, rather than being capable of using either NAD(H) or NADP(H). In this respect, the coelenterate phyla appear to be unique in the animal kingdom.
Development of the compound eyes of dragonflies (odonata). IV. Development of the adult compound eyes
Authors: Sherk Truman E.
Published: June 2005

The changes in the directions of view of marked larval ommatidia were observed after the emergence of the adult. Those ommatidia that had been present during the first larval instar had the most posterior directions of view in the adult visual field while the newest ommatidia that had not been functional for vision in the aquatic larva contributed to the anterior and dorsal foveas of the aerial adults.

The changes in interommatidial angles at emergence are discussed. Contrary to the general trend for interommatidial angles between retained larval ommatidia to decrease at emergence, the interommatidial angles in the larval fovea of aeshnid visual predators increase at emergence.

The modifications in an odonate compound eye at emergence are like an exaggeration of the modifications that occur at the moult from one larval instar to the next, except that the newest ommatidia do not have any compromises in their design for use in the aquatic vision of the larvae. This is in contrast to the ommatidia retained from the earliest larval instars which have to have the most compromises in their design so that they can be adapted for the visual requirements of every larval instar, as well as the adult. This is discussed in relation to the trend among advanced species of odonates to replace the larval ommatidia by an entirely new set of adult ommatidia.
Endocrine control of larval fat body histolysis in normal and mutant Drosophila melanogaster
Authors: Postlethwait John H. , Jones Gary J.
Published: June 2005

In Drosophila melanogaster, about a thousand larval fat body cells survive metamorphosis, but histolyze and disappear in the first few days of adult life. We wondered what hormonal factors control larval fat cell disappearance in normal and mutant flies. In order to test the effect of anterior endocrine organs, we isolated abdomens from the head and thorax of newly eclosed flies. In isolated abdomens fat cells disappeared at a much slower rate, decreasing by only 30% instead of 100% by 72 hours. To find if the juvenile hormone was responsible for this result, we treated isolated abdomens with ZR‐515, a juvenile hormone analogue. In ZR‐515 treated isolated abdomens, the fat cell number decreased by 94% at 72 hours. This shows that juvenile hormone activity can replace the lytic factor missing from isolated abdomens. The mutation ap4 retards the rate of fat cell lysis: only 47% of the cells disappear by 48 hours compared to 99% in heterozygous controls. To find if JH activity could restore the normal phenotype, we treated these mutants with ZR‐515. The result was that hormonetreated mutants at 48 hours had destroyed 88% of their fat cells, thereby approaching the normal situation. To study the effect of an inhibitor of protein synthesis, we injected cycloheximide into freshly eclosed normal flies. A dose of 0.3 μl of 6 × 10−4 gm/ml cycloheximide inhibited both vitellogenesis and larval fat cell disappearance. This inhibition could not be overcome by administration of ZR‐515. From these studies we conclude that juvenile hormone activity is required for larval fat cell disappearance in both wild type and mutant flies. Since cycloheximide inhibits larval fat cell disappearance even in the presence of a juvenile hormone analogue, it is suggested that the lytic effect of juvenile hormone is mediated via protein synthesis.
Effects of puromycin and actinomycin D on fertilized rabbit eggs cultured in vitro
Authors: Longo Frank J.
Published: June 2005

Rabbit zygotes were cultured in media containing varying concentrations of puromycin and actinomycin D in order to determine what effect these agents have on events of fertilization and early development. Concentrations of puromycin greater than 10−5 M inhibited mitosis, cytokinesis of fertilized eggs and leucine incorporation. In approximately 50% of the zygotes treated with puromycin (10−5 M or greater) the female pronucleus remained at its site of formation, the cortex, and did not migrate centrad. In these instances the male pronucleus moved from its site of development to the female pronucleus. Concentrations of actinomycin D greater than 10−7 M also inhibited mitosis and cytokinesis of fertilized eggs. Breakdown of the nuclear envelopes and association of the paternally‐ and maternally‐derived chromatin did not occur in either puromycinor actinomycin D‐treated embryos. Actinomycin D at all of the concentrations employed (10−9 to 10−4 M) had little effect upon the structure of nucleolus‐like bodies within male and female pronuclei. Male and female pronuclei of puromycin (10−4 M) and actinomycin D (10−5 M) treated zygotes, incubated with tritiated thymidine and prepared for scintillation counting and autoradiography, synthesized DNA at a reduced level when compared to control specimens. Although “side effects” of puromycin and actinomycin D treatment are not excluded, these results suggest that nascent proteins may be required for events of fertilization.
The possible role of hemidesmosomes in neonatally estrogen‐induced selection of a permanently altered abnormal vaginal epithelium
Authors: Cunha Gerald R. , Lee Andrew K.
Published: June 2005

In untreated and neonatally‐estrogenized (E) Balb/c mice the numbers of hemidesmosomes per basal cell cross section (HD/bccs) gradually increases from 0.07 HD/bccs on day 1 to about 2 to 3 HD/bccs on day 4 postpartum. In untreated mice the incidence of HD's increases and plateaus at 6 to 7 HD/bccs on days 5 and 8, while during this same period in E‐treated mice the incidence is increased to 14 to 15 HD/bccs. In 5‐day‐old E‐treated mice two types of basal vaginal epithelial cells can be recognized: basophilic cells rich in HD (19.5 ± 2.1 HD/bccs) and light cells containing only 5.3 ± 3.3 HD/bccs. The basophilic, HD‐rich cells appear to replace the lighter HD‐poor cells. The hypothesis that HD's are involved in the estradiol‐induced selection of an abnormal vaginal epithelium is discussed.
Nerve dependent macromolecular synthesis in the epidermis and blastema of the adult newt regenerate
Authors: Geraudie Jacqueline , Singer Marcus
Published: June 2005

The present study is an analysis of neurotrophic control of DNA and protein synthesis in the separated epidermis and blastema of the early newt limb regenerate. Previous macromolecular studies employed the entire regenerate without discrimination between its two components. The results demonstrate that the specific activities of newly synthesized protein and DNA show a nerve dependence in both epidermis and blastema. There appears to be a postdenervation rise in synthesis followed by a decline to a plateau level in both components, similar to what is reported for the whole regenerate. After two days of denervation DNA synthesis in the mesenchymatous cells is more profoundly depressed, suggesting that the epidermis is less nerve dependent.
Trophoblast regeneration by inner cell masses isolated from cultured mouse embryos
Authors: Spindle Akiko I.
Published: June 2005

The developmental potential of the inner cell mass (ICM) of the cultured mouse embryo was determined by testing the ability of the ICM to regenerate trophoblast in vitro. ICM's isolated by immunosurgery from either single or chimeric embryos were able to regenerate trophoblast when they were isolated at 69 hours of culture from the 2‐cell stage, but they had lost this capacity by 93 hours of culture. Trophoblast regeneration by isolated ICM's did not appear to require either a critical cell mass at the time of isolation or cell proliferation during regeneration.
Regeneration of ciliary pattern in longitudinal fragments of the hypotrichous ciliate, Stylonychia
Authors: Grimes Gary W. , Adler Joseph A.
Published: June 2005

Longitudinal fragments of the hypotrichous ciliate Stylonychia were studied at various stages of cortical regeneration by Scanning Electron Microscopy. Analysis showed that (except for the oral primordium) all primordial fields responsible for replacing excised ciliature develop in continuity with existing primordia; i.e., all ciliary primordia are derived from segments originally continuous with the oral primordium. This observation leads to the concept of a single primordial field, a “primordium of the ciliature,” possessing the developmental competence of giving rise to a complete set of ciliary structures. Such a concept implies the operation of a reciprocal intra‐cortical communication system; i.e., the developmental manifestations of any individual primordium are determined at least in part by the precise location of morphostatic and/or primordial ciliary structures. An intra‐cortical communication system is consistent with the previously proposed “determinative region” (Grimes, '75), the function of which is to serve as the initiation site of a primordium during excystment morphogenesis.
Oogenesis in Xenopus laevis (Daudin) VI. The route of injected tracer transport in the follicle and developing oocyte,
Authors: Dumont J. N.
Published: June 2005

In Xenopus laevis, vitellogenin (the yolk precursor) is synthesized in the liver and transported via the circulatory system to the ovary. In order to reach developing oocytes where it is sequestered, it must exit the circulatory system and traverse several follicular tissue layers including the theca, the follicle cell layer, and the vitelline envelope. This study demonstrates this pathway by means of electron‐opaque tracers, and follows the fate of heterologous macromolecules after their incorporation into the ooplasm. The tracers used were horseradish peroxidase, iron dextran, ferritin, and thorotrast. The bulk of the tracers exit the circulatory system through gaps between adjacent capillary endothelial cells and migrate into the connective tissue theca, where they appear randomly dispersed. All tracers, except thorotrast, penetrate the basement membrane on the distal surface of the follicle cells and pass through channels between adjacent follicle cells into the vitelline envelope and to the surface of developing oocytes, where they are incorporated by endocytosis. Endosomes which contain tracer, and also presumably vitellogenin, fuse to form primordial yolk platelets. During this fusion process an extensive network of smooth‐surfaced tubules arises in the peripheral ooplasm. Endosomes and/or primordial yolk platelets continue to fuse with each other, resulting in the growth of primordial platelets which move deeper into the ooplasm, where they are transformed into yolk platelets with crystalline main bodies. Peroxidase and iron dextran remain in the superficial layer of the platelet, while ferritin is present in both the superficial layer and the crystalline main body.
Quantitative behavioral studies of misdirected responses in skin‐grafted Rana pipiens
Authors: Heidemann Merle Knudson
Published: June 2005

The experiments reported here describe quantitatively wiping responses elicited from three equal body sections of adult Rana pipiens having had one of two types of skin‐graft operations as tadpoles. These experiments assessed the development of abberant wiping responses in individuals and populations of grafted animals. Grafting parameters critical for the development of aberrant wiping responses were also determined. These studies indicated that the phenomenon of “misdirected responses” and the extent of these responses is highly variable among grafted individuals and between different populations of grafted animals. In addition, the development of “misdirected responses” is independent of premetamorphic stimulation and of a critical grafting period. The pro‐portion of “misdirected responses” elicited upon cutaneous stimulation of individuals appears to be stable and predictable after metamorphosis. “Misdirected responses” could be elicited from animals with grafts including over 40% of the trunk skin. Wiping responses and grafting parameters of skin‐grafted R pipiens in other studies are also presented and possible sources of interstudy variation discussed.
Light‐sensitive fish melanophores in culture
Authors: Wakamatsu Yuko
Published: June 2005

Dermal melanophores in the skin from embryos and young fishes of the black platy fish, Xiphophorus maculatus, were dissociated and cultured in a monolayer. Melanosomes in the melanophores were dispersed in culture. Some of the cultured melanophores directly responded to light by producing reversible melanosome aggregation within a few minutes. A dose‐response relationship was found between light intensity and time required for melanosome aggregation.
The failure of double‐half forelimbs to undergo distal transformation following amputation in the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W.
Published: June 2005

Although capable of initiating early regenerative responses, axolotl forelimb stumps which are composed of double‐half limb tissues fail to undergo the events that normally lead to the replacement of missing parts. In the present study, the posterior halves of right forelimbs were exchanged with the anterior halves of left forelimbs, or the dorsal halves of right forelimbs were exchanged with the ventral halves of left forelimbs. Forelimbs were amputated through the graft region 30 days after grafting. Limb stumps bearing double‐dorsal, double‐ventral or double‐posterior tissues either produced hypomorphic regenerates or failed to form any externally visible outgrowth. When the limb stump bore double‐anterior tissues, no externally visible structures were formed. Normal and multiple regenerates were never formed by double‐half limbs. These results are discussed in terms of the polar coordinate model and suggest that the regeneration blastema requires a complete circumference of positional values in order to complete distal transformation.
Seasonal effects on osmotic permeability of Rana pipiens in vivo and in vitro
Authors: Parsons Robert H. , Brady Robert , Goddard Bryan , Kernan Donald
Published: June 2005

Dependence on season of the osmotic water permeability (Lp) of the skin of whole frogs and isolated preparations of frog leg and abdominal skin have been determined. The Lp of frog skin in vivo and in vitro increases during the summer. However, the increase in vivo occurs in April while the increase in vitro does not occur until August. Injection of arginine vasopressin (ADH) into whole frogs in July produces a 200% increase in the osmotic water permeability, while the same injection in March induces only a slight increase. Isolated abdominal skin shows a similar effect upon stimulation by 500 mU/ml of ADH: a large increase in July with a barely detectable effect in March. Isolated leg skin does not show a response to this level of vasopressin either in July or March. The possibility that seasonal changes in the osmotic permeability of whole animals can be attributed to seasonal variations in sensitivity to ADH is discussed.
Mammalian pyruvate kinase hybrid isozymes: Tissue distribution and physiological significance
Authors: Cardenas Janet M. , Dyson Robert D.
Published: June 2005

The purpose of this study was to examine the pyruvate kinase isozymic patterns of a wide variety of tissues from rats and mice, particularly regarding hybrid isozymes. For these studies, we employed longer electrophoresis times than used in most earlier studies in order to improve the resolution of closely spaced bands. The tissue distributions of types K, L, and M pyruvate kinases were found to be approximately the same as those reported earlier for rats and other mammals. In addition, K–M hybrids could be detected in most tissues examined in relative quantities which differed from one tissue to another in the same organism, in corresponding tissues from different species, and within a single tissue during development. Hybrid isozymes containing type L subunits occur in only a few tissues of either the fetus or the adult of either animal.

In earlier studies utilizing L–M hybrid isozymes produced in vitro, we showed that the kinetic properties of a given subunit are profoundly affected by the nature of its neighbors within the tetramer (Dyson and Cardenas, ['73] J. Biol. Chem., 248: 8482–8488). Based on these altered kinetic properties, we suggest that there is little need for an organism to suppress completely the gene activity for one subunit type of pyruvate kinase during the synthesis of larger quantities of a second subunit type.
Induced formation of asters and cleavage furrows in oocytes of Xenopus laevis during in vitro maturation
Authors: Heidemann Steven R. , Kirschner Marc W.
Published: June 2005

We have previously reported that injection of purified basal bodies or sperm into unfertilized eggs of Xenopus laevis induced the formation of asters and irregular cleavage furrows. Fully grown oocytes were found to be unable to form asters or cleavage furrows. In this paper we show that the oocyte acquires the ability to form asters upon basal body injection at the time of germinal vesicle breakdown during in vitro maturation. Our evidence indicates that aster formation requires progesterone‐stimulated changes in the oocyte and mixing of cytoplasm and germinal vesicle plasm. The ability of the oocyte to form cleavage furrows arises six to eight hours after germinal vesicle breakdown. We infer that some maturational change in the cell cortex occurs to enable the egg surface to furrow. Experiments on the relationship of aster formation to furrow initiation indicates that asters stimulate furrow formation. However, some furrowing could be induced without aster formation in mature oocytes and unfertilized eggs by an activation stimulus, showing that asters are not essential for cleavage initiation. The significance of these observations are discussed in the light of our current understanding of meiotic maturation, cell cleavage and aster growth.
The possible influence of temporal factors in androgenic responsiveness of urogenital tissue recombinants from wild‐type and androgen‐insensitive (Tfm) Mice
Authors: Cunha Gerald R. , Lung Ben
Published: June 2005

Tissue recombinants of epithelium and stroma from embryonic and neonatal urogenital rudiments derived from wild‐type and femininized (Tfm/Y) mice were grown as grafts in intact male hosts and analyzed morphologically for androgenic response. When mesenchyme of embryonic wild‐type urogenital sinus (UGS) was associated with epithelium from embryonic wild‐type bladder (B), the epithelium developed into glandular structures resembling prostate. In the reciprocal recombinant (B mesenchyme + UGS epithelium) the response was mixed, half of the recombinants exhibited bladder morphology and half exhibited prostatic‐like morphology.

Vaginal‐like histogenesis occurred in UGS recombinants of androgen‐insensitive Tfm/Y mesenchyme and wild‐type epithelium, while prostatic morphology developed in reciprocal recombinants of wild‐type mesenchyme and Tfm/Y epithelium. These observations demonstrate (1) that the presence of wild‐type mesenchyme appears essential for expression of androgen‐dependent morphogenesis during embryonic periods; and (2) that Tfm/Y epithelium is capable of participating in an androgenic response. Conversely, in similar recombinants prepared with neonatal tissues, the presence of wild‐type urogenital stroma may not be required for expression of certain androgen‐dependent phenomena since maintenance of the height and cytodifferentiation of ductus deferens epithelium occurs even when this epithelium is associated with Tfm/Y urogenital stroma. It appears, therefore, that the requirement of urogenital epithelium for wild‐type (androgen sensitive) stroma may vary temporally.
Biochemical and autoradiographic analysis of regeneration in two hydroids
Authors: Samuelson Marlene , Lesh‐Laurie Georgia E.
Published: June 2005

Podocoryne carnea and Hydractinia echinata are organisms at a similar taxonomic level with different regenerative abilities. This investigation compared biochemical events following wounding of these organisms, and additionally examined autoradiographically the incorporation of macromolecular precursors into cells in the cut, proximal area of their gastrozooids.

Although the non‐regenerating gastrozooids of both organisms incorporated little 3H‐thymidine into cells near the proximal tip, amputation provided a stimulus for cells in this area of both organisms to incorporate greater levels of this precursor. However, the level of stimulation of total incorporation into gastrozooids was substantially greater in Podocoryne. During regeneration, Podocoryne gastrozooids were stimulated to incorporate peak levels of 3H‐uridine into RNA at 6, 15 and 24 hours, whereas Hydractinia gastrozooids exhibited no peak levels of incorporation throughout the 27‐hour post‐wounding period. In the initial nine hours following wounding, Podocoryne gastrozooids were stimulated to much greater levels of incorporation of 3H‐leucine into protein over non‐regenerating gastrozooids than were Hydractinia polyps.

Therefore, the results of this biochemical and autoradiographical investigation demonstrated that Podocoryne gastrozooids, which regenerate proximally, had substantially higher levels of stimulation of precursor incorporation into macromolecules during 27 hours following wounding than Hydractinia gastrozooids, which do not regenerate proximally. Additionally, when this level of incorporation was depressed by the use of inhibitors in Podocoryne polyps, they were unable to complete regeneration in the normal manner.
Studies on the regeneration of an entoproct, Barentsia discreta
Authors: Mukai Hideo , Makioka Toshiki
Published: June 2005

Regeneration of a colonial entoproct, Barentsia discreta, was studied. In the colony, the stolon is subdivided into alternately arranged fertile and sterile sections by annular septa. The zooid consists of a stalk arising from the fertile section and an apical calyx; the stalk comprises a single “muscular node” at its base and a slender “rod.” In regeneration occurring after partial degeneration of a zooid, the following three types can be distinguished: calyx, rod and zooid regeneration. Double malformations of the calyx were obtained. The double calyx seems to result from calyx regeneration effected without loss of the original calyx. Amputations were made at various levels of the stalk and regeneration both from the cut stump and from the cut piece was observed. The rod can regenerate a calyx both apically and basally. The muscular node can regenerate a calyx apically but can not basally. In every regenerate, the original oral‐anal axis is retained. Continuous contact of calyces with glass slides induced the formation of a muscular node between the calyx and the rod. The stolon can regenerate distally from any site of the fertile or the sterile section, but can not regenerate proximally. Stolons with two serially arranged sterile sections were obtained when amputations were made at the proximal site of the fertile section.
The subcommissural organ of Lacerta s. sicula raf.: Effects of experimental treatments on castrated animals during winter
Authors: D'uva V. , Ciarcia G. , Ciarletta A. , Angelini F.
Published: June 2005

The AA. have studied the effects of testosterone administration and of temperature increase on the subcommissural organ (SCO) of Lacerta s. sicula Raf. castrated during the winter. Testosterone administered to specimens at environment temperature did not cause stimulation of the SCO. It was sufficient to raise the temperature to obtain stimulation. At 28° C the SCO of castrated animals was also stimulated, but after more time and less intensely than in normal animals.
Role of divalent cations in the resumption of meiosis of rat oocytes
Authors: Tsafriri Alexander , Bar‐Ami Shalom
Published: June 2005

Resumption of meiotic maturation was induced in follicleenclosed rat‐oocytes by treatment with the divalent cationophore A23187 (10−5M). However, the same effect was attained by incubation in Ca++ ‐ deficient medium, even in the presence of EDTA or EGTA (lmM). The stability of the first polar body was increased under Ca++ ‐deficient conditions. Neither the ionophore nor Ca++ ‐deficient medium interfered with the spontaneous maturation of isolated oocytes of the rat. The experiments with cultured follicles suggest that redistribution of divalent cations may participate in the physiological control of meiosis in mammalian oocytes.
Environmental influence on testicular activity in the green frog, Rana esculenta
Authors: Rastogi R. K. , Iela L. , Delrio G. , Di Meglio M. , Russo A. , Chieffi G.
Published: June 2005

Adult male Rana esculenta were placed under several combinations of light and temperature in different periods of the year to elucidate the regulation of various testicular phases by environmental factors and to discover the mechanism through which these factors act upon the testis. In nature the quiescence of spermatogenesis in winter is due solely to low temperature. Under controlled experimental conditions a temperature of 4°C, whatever the photoperiod, impairs spermatogenesis at any time of the year. The early spring resurgence of a new wave of spermatogenesis depends upon a gradual rise both in the environmental temperature and the photoperiod. In fact in nature the temperature range favorable for active spermatogenesis is between 12°C, and 25°C with a period of between 10 and 16 hours of light daily. In the laboratory a temperature of ca. 20°C and a period of 12 hours of light daily represent the best combination of these factors for regulating and maintaining active spermatogenesis in any period of the year. Very long (21 hours of light daily) and very short (3 hours of light daily) photoperiods, however, have deleterious effects upon the testis. These effects are manifested mainly in the suppression of primary spermatocytes and successively in a gradual decline in number of secondary spermatocytes and spermatids and appearance of numerous degenerating cell nests. The same occurs when the frogs are treated at very low temperature. Besides this, high temperature stimulates plasma levels of testosterone which does not occur if the animals are kept in the dark. Very low temperature, on the other hand, has the opposite effect.

These data suggest that a combination of “critical temperature” and “critical photoperiod” is necessary for regulating and maintaining active spermatogenesis since neither of these factors is effective in the absence of the other. The stimulatory effects of high temperature are due to the increased secretory activity of the pituitary gonadotropin.

Furthermore the present results also indicate that the testis of Rana esculenta does not manifest any seasonal change in the degree of its response to thermal and/or photoperiodic regulation i.e., it does not show photo‐ or thermal refractoriness during the year.
The synthesis of melatonin by the trout retina
Authors: Gern William A. , Owens David W. , Ralph Charles L.
Published: June 2005

Trout retinae were shown to contain melatonin, which was present in highest (p<.05) concentration during the photophase portion of a light‐dark cycle. Pinealectomy was found not to perturb either the rhythm or the titer of retina melatonin. These results suggest that the trout retina is a melatonin‐synthesizing tissue.