bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of hydroplasmic pressure in stolonic growth movements in the hydroid, Bougainvillia
Authors: Wyttenbach Charles R.
Published: June 2005

The effects of intrastolonic pressure on growth activity of the stolon have been ascertained by simultaneously observing the direction of hydroplasmic flow and movements of the stolon tip at close time intervals over many consecutive growth cycles. During each growth cycle (4.4–5.8 minutes long) the tip passes through three distinct stages of inherent retractile potential and associated responsiveness to hydroplasmic pressure. (1) Beginning abruptly at the crest, it displays a strong retractile propensity: low pressure (from proximal flow) elicits a retraction of up to 5.5 μ per 0.2 minute, until the onset of distal flow (increasing pressure) causes it to immediately re‐extend. Thus the depth of retraction is directly determined by the degree and duration of low pressure following the crest. (2) After 1.8–2.0 minutes this retractile tendency becomes suddenly diminished. The tip, if still retracted, now re‐extends regardless of the intrastolonic pressure, and proximal flow during the middle third of the cycle causes only a delayed and shallow retraction to define an intermediate peak. (3) During the final third of the cycle the tip is nonresponsive to hydroplasmic pressure: even under circumstances of lowest pressure, it extends forward to a new crest. It is suggested that this varying retractile capacity may be associated with the pattern of changing thickness of the epidermal layer at the stolon tip.

Certain features of the hydroplasmic flow and stolon growth cycles appear to be interrelated, most notably the consistent cessation of proximal flow in relation to a crest or trough. Thus some degree of control seems likely between the stolon tip and the contractile zone responsible for flow.
Inductive role of the nerve cord in regeneration of isolated postpharyngeal body sections of Dugesia dorotocephala
Authors: Sperry Pamela J. , Ansevin Krystyna D. , Tittel Frank K.
Published: June 2005

Lateral cordless fragments isolated from the postpharyngeal section of Dugesia dorotocephala formed a large normal head at a 90° angle to the original antero‐posterior polarity; postcerebrally, only a hump of undifferentiated tissue developed. This “head‐hump” pattern, and also other types observed in previous studies of lateral fragments, were attributed to the absence of the nerve cord. In order to confirm the inductive role of the nerve cord and to eliminate the possibility that the “head‐hump syndrome” was due to the relative proportions of other tissues besides nerve, body fragments of two experimental groups were observed: (1) the five types of fragments which had no nerve cord but had varying proportions of other tissues present formed primarily “head‐hump” types of regenerates. (2) Almost all fragments which had varying amounts of nerve cord present but the same proportions of other tissues formed regenerates of normal body proportions. Therefore, the absence of the nerve cord does determine the “head‐hump syndrome”.

Isolated postpharyngeal half segments containing one nerve cord were allowed to regenerate for varying periods of time before the lateral cordless fragment was isolated. The number of “head‐hump” regenerates from lateral fragments isolated after a one‐day or longer contact with the nerve cord gradually decreased, and the number of regenerates with incomplete head development or which were more elongated postcerebrally increased. These results indicate that the nerve cord acts gradually to determine the differentiation of specific tissues rather than rapidly to determine the overall body plan.
A serologic comparison of bat complements
Authors: Hatten Betty A. , Lutskus Joseph H. , Sulkin S. Edward
Published: June 2005

Complement levels of four species of bats were much lower than in guinea pigs when measured by immune hemolysis, bactericidal and immune adherence procedures. Serum pools from three species of Microchiroptera showed somewhat higher levels of complement activity by the immune hemolysis procedure than the megachiropteran species, but not by the immune adherence procedure. Kinetic studies indicated that activities of P. vampyrus and E. fuscus complements were similarly affected by changes in ionic strength of the buffer, but not by changes in pH or in concentrations of divalent ions (Ca++ and Mg++). Eptesicus species of bat complement also gave maximum rates of lysis over a wider range of incubation temperatures than did P. vampyrus and guinea pig complements. Guinea pig complement mediated lysis equally well with rabbit, guinea pig, and bat antibodies. E. fuscus complement showed maximum lytic activity with guinea pig and rabbit antibodies, and P. vampyrus complement with guinea pig antibodies. Minimal lysis occurred when mammalian complements and antibodies were combined with chicken antibodies and complement, respectively. Functionally purified C1 components of guinea pig, chicken, and P. vampyrus and E. fuscus bat complements mediated immune lysis with guinea pig C2–9, but demonstrated little lytic activity in the presence of E. fuscus and chicken C2–9. No significant immunologic correspondence was shown between any of the four species of C1 components by immunodiffusion or turbidimetric procedures. Similar patterns of naturally occurring hemolytic activity present in P. vampyrus and E. fuscus sera for erythrocytes from a wide variety of animals were distinct from patterns obtained with guinea pig and chicken sera. Occurrence of agglutination with some species of cells in addition to or in the absence of hemolysis, however, suggested variations in the specificity of these species of complement for different cell surfaces.
Molecular basis for multiple forms of LDH‐X
Authors: Goldberg Erwin
Published: June 2005

The guinea pig has three molecular species of LDH‐X which are inhibited by antiserum directed against the C subunit. Only two of these are selectively inhibited by anti‐A polypeptide antiserum. Heterotetramers produced by in vitro dissociation and recombination of isozymes and containing B‐C subunit combinations are selectively inhibited only by the anti‐C antiserum. Therefore, the subunit composition of these multiple forms of LDH‐X are: CCCC; CCCA; CCAA. Similarly, rat testes contain two forms of LDH‐X which can be described as CCCC and CCCA tetramers.
Germination of the statoblasts of a freshwater bryozoan, Pectinatella gelatinosa
Authors: Mukai Hideo
Published: June 2005

Pectinatella gelatinosa has only one generation of statoblasts a year. The statoblasts are dormant when they are formed in summer. When they were kept in water under laboratory conditions, dormancy was gradually broken from late autumn to early spring of the following year. No effective means was found to induce germination in the dormant statoblasts. Some substance(s) which inhibits the germination of statoblasts, hence called blastostasin, was demonstrated in the water in which statoblasts had been stored for a long period. The optimum temperature for germination is about 25°C. Light is an essential factor but is needed for only the initial phase of germination. Prolonged periods of illumination with strong light are inhibitory. Visible light with wavelengths longer than green is effective for germination. Undried statoblasts remained viable for more than three years. Some germination was also obtained from statoblasts dried for 20 months. Undried statoblasts can resist prolonged periods of freezing but are very sensitive to high temperature.

It is suggested that the effectiveness of critical experimental factors varies with the previous history of statoblasts. Various unfavorable, but not lethal, treatments resulted in temporary loss of germinability and brought the statoblasts into a resting state, for which the term “induced dormancy” is proposed.
The pattern of morphogenetic control in Chilodonella cucullulus
Authors: Kaczanowska Janina
Published: June 2005

The formation of positional information in cells involves the determination of a geometrical point pattern in a developing system. The translation of genetic information into a spatial pattern is achieved in the unicellular ciliate Chilodonella cucullulus by the two‐dimensional cortical surface which specifies a non‐random distribution of continuously dispersed organelles during the early stage of divisional morphogenesis.

The supposed mechanism of positioning operates in a system of spatial coordinates and the system possesses definite reference points and boundaries. One reference point is the site of the oral apparatus. This site, at the stage of early divisional morphogenesis of Chilodonella, acts as a source of positional information specifying the sites of the daughter reference points (centers). These centers specify the sites of differentiation of primordia of the contractile vacuole pores (CVPs). This positional information is regulated by the boundaries of the ventral surface and the topography of the postoral sector. Specified sites of differentiation may be shifted somewhat eventually by structural guidance factors.

Inter‐ and intraclonal polymorphism of C. cucullulus suggests that a genie basis for parameters of positioning also exists.

The congruence between the model of positional information in multicellular systems (Wolpert, '69, '71) and the analysis of morphogenetic pattern in C. cucullulus is discussed. The cell surface membrane is envisaged as the possible structural site of the mechanism of positioning.
Serum composition of the coelacanth, Latimeria chalumnae Smith
Authors: Griffith Robert W. , Umminger Bruce L. , Grant Blake F. , Pang Peter K. T. , Pickford Grace E.
Published: June 2005

Inorganic and organic constituents were studied on blood serum collected from a living specimen of the coelacanth, Latimeria chalumnae. Inorganic electrolytes determined included sodium (196.7 mM/l), potassium (5.78 mM/l), magnesium (5.30 mM/l), calcium (4.94 mM/l), chloride (186.7 mM/l), bicarbonate (9.60 mM/l), phosphate (5.08 mM/l), and sulfate (4.80 mM/l). Serum urea (377 mM/l) and trimethylamine oxide (122 mM/l) were high as previously reported, and accounted for the bulk of the total non‐protein nitrogen (1199 mg%); total amino acids added a small but not insignificant fraction (21.9 mg%). High serum lactate (16.5 mM/l) and glucose (6.57 mM/l) levels were probably indicative of stress; glucose was the only carbohydrate present in appreciable amounts in the serum, although traces of glucuronic acid and rhamnose were found. Serum total cholesterol was 3.91 mM/l, organically bound phosphorus 1.99 mM/l and total proteins 2.84 g%. Three major protein fractions were evident from cellulose acetate electrophoresis and at least 11 peaks were demonstrable by acrylamide gel electrophoresis. Latimeria serum lacks a protein component with a mobility approaching that of human serum albumin. Serum osmolarity (932 mOsm/l) was somewhat lower than that of sea water collected at the site of capture of the specimen (1035 mOsm/l). Evolutionary implications of the similarity of Latimeria serum chemistry to that of other marine fishes are discussed.
Ultrastructural effects of dark‐adaptation on eyes of a snail. Helix aspersa
Authors: Eakin Richard M. , Brandenburger Jean L.
Published: June 2005

Pulmonate snails (Helix aspersa) were raised from embryos to adulthood in total darkness. Unique ultrastructural features found in their photosensory cells were: 1. Break up of large aggregations of 800 A photic vesicles into smaller clusters by thick layers of membranes. 2. Increase in lipid droplets and in number and size of lysosomes. 3. Decrease in formation of photic vesicles by Golgi centers. 4. Flattening and bending of the tips of the microvilli. Tentative conclusions: the reduction in number of photic vesicles in dark‐adapted snails, by break down and decreased production, supports the hypothesis that the vesicles transport materials (photopigment ?) essential for light‐sensitivity of the microvilli.
In vitro effects of prolactin and cortisol on water permeability of the urinary bladder of the teleost Gillichthys mirabilis
Authors: Doneen Byron A. , Bern Howard A.
Published: June 2005

Urinary bladders of the euryhaline teleost Gillichthys mirabilis were maintained in organ culture under defined conditions for four days. Examination of bladders cultured in medium containing cortisol or prolactin or both hormones indicates that cortisol increases bladder water permeability and that prolactin antagonizes the cortisol effect, causing a reduction in water permeability. Bladders co‐cultured with teleost pituitaries or with teleost rostral pars distalis is show a pronounced reduction in osmotic permeability. The effects of prolactin and cortisol in vivo appear to be reproducible in vitro.
Functional volume of frog eggs: Equivalence of metabolite diffusion space in chemically demembranated embryos and aqueous phase (non‐yolk) volume
Authors: Melton C. G. , Smorul R. P.
Published: June 2005

Vitelline membranes were removed from two‐cell Rana pipiens embryos by papain‐cysteine. Uptake of several different metabolites was enhanced, some more than others, but they all slowly reached about the same plateau, 11.2–13% (average) volumetric equilibration of the embryos with the radioactive medium. Active transport was ruled out as the uptake mechanism.

Similarly, direct measurement of the volume of the aqueous phase, or “non‐yolk” cytoplasm, of egg homogenates gave an average value of 12.3% of the total egg volume. We conclude that this represents the available embryonic diffusion space and that the metabolites saturated it by passive diffusion. The importance of the concept of non‐yolk cytoplasm, or egg functional volume, as a developmentally significant parameter is discussed.
Further evidence for a developmental change in morphogenetic properties of embryonic chick heart cells
Authors: Lesseps Roland J. , Brown Shelia A.
Published: June 2005

Recent experiments involving the reaggregation of dissociated cells and fusion of intact tissue fragments have indicated that whereas heart cells and tissue fragments from young chick embryos (1.5–2 days) displayed a tendency to assume external positions in combination with neural tube, those from older embryos (4–5 days) tended to segregate to the inside of neural tube. In the present experiments, we have used the same techniques in conjunction with autoradiography to determine the relative positions of two‐day and five‐day heart ventricle cells in fusion masses and in reaggregates. Sections of 30 fusion masses revealed that the two‐day heart fragment enveloped the five‐day heart fragment in every case. Sections of 29 reaggregates showed that the two‐day and five‐day heart cells were still randomly mixed at the end of the two and one‐half day culture period. The consistent spreading of intact two‐day heart ventricle fragments over five‐day heart ventricle fragments confirms the indication of the previous experiments that heart cells change their morphogenetic properties between two days and five days of incubation. The failure of five‐day and two‐day heart cells to sort out from one another could be due to a decreased cohesiveness of five‐day heart cells caused by the trypsin dissociation procedure.
Effect of experimentally induced anemia on the testicular activity of the toad (Bufo melanostictus)
Authors: Boral M. C. , Kaul Pratibha , Dey Sudhansu K. , Deb C.
Published: June 2005

Anemia induced experimentally either by administration of phenylhydrazine or by splenectomy stimulated spermatogenic and steroidogenic activities in the testes of the toad (Bufo melanostictus). It is concluded that the stimulated activity of the testes is mediated through the hypothalamo‐pituitary axis.
The occurrence and possible functional significance of ‐S‐S‐ crosslinks in sperm heads, with particular reference to eutherian mammals
Authors: Bedford J. M. , Calvin H. I.
Published: June 2005

The extraordinary resistance to disruption shown by the eutherian sperm nucleus is associated with a significant complement of ‐S‐S‐ crosslinks within the chromatin. The present light and electron microscopic study, in which the spermatozoa of many vertebrates and some invertebrates were exposed to SDS with or without dithiothreitol, demonstrates that the extreme degree of disulfide bonding in the sperm chromatin of eutherian mammals is highly unusual in a comparative sense. In no other species did the sperm nucleus display a resistance to disruption comparable to that in eutherians; on the contrary, in most groups including prototherian and metatherian mammals, such crosslinks are absent or relatively sparse, the greatest degree of crosslinking outside the eutheria being seen in octopus and skate.

The suggestion is advanced that the unusually thiol‐rich protamines have evolved as a structural adaptation which, through crosslinking, endows the sperm head with a rigidity of possible importance in the penetration phase of fertilization. This seems likely because (1) any degree of ‐S‐S‐ determined stability present or inducible in sperm chromatin often appears more intense in or is confined to the anterior region of the nucleus (e.g., newt, snail, turtle and immature eutherian spermatozoa); (2) the zona pellucida, which the fertilizing sperm must penetrate, is an unusually thick, compact and resilient coat in the eutherian ovum in particular; and (3) the occasional observation of a sperm nucleus buckled within the pathway of its penetration into the rabbit zona pellucida suggests that in eutheria this tough vestment presents a relatively rigid barrier to the sperm head.

Its apical location suggests a similar structural role for the ‐S‐S‐ stabilised perinuclear projection, or “perforatorium” around the leading border of the sperm nucleus in eutherians as well as in some non‐eutherian species, such as octopus, snake and turtle.
Spermatozoan vesicle loss during penetration of the female gonangium in the hydroid. Campanularia flexuosa
Authors: O'Rand Michael G. , Miller Richard L.
Published: June 2005

Fertilization in the hydrozoan Campanularia flexuosa is internal and may be considered to include events in the female reproductive organ (the gonangium) prior to zygote formation. Prior to fertilization the spermatozoan must move through the female gonangium to the site of sperm‐egg fusion. The female gonangium contains sheets of epithelial cells which distally line the entrance and proximally form passageways that lead to and surround the eggs. After chemotactic attraction to the gonangium aperture, the spermatozoa adhere to the epithelial cells by their outer surfaces, but they continue to move downward along the distal gonangium epithelia and through the passageways to the germinal vesicle area of the egg. As the spermatozoa move deeper into the gonangium the 640–700 Å membrane‐bounded (“pro‐acrosomal”) vesicles of the sperm progressively decrease in number. By the time the spermatozoa reach the egg, 88% of the vesicles have been lost. It is possible that the contents of the vesicles play a role in the control of spermatozoan‐epithelial cell adhesion or that they serve, in some way, to permit sperm penetration to the egg surface. Alternatively, their loss may be a morphological indication of the capacitation‐like interaction between the sperm and normal female gonangium epithelial cells which is required for fertilization in Campanularia flexuosa.
Surgical approach to the dolphin's ear
Authors: Ridgway Sam H. , McCormick James G. , Wever Ernest Glen
Published: June 2005

A surgical approach to the cetacean (Tursiops truncatus and Lagenorhynchus obliquidens) ear represented a unique problem. The first obstacle was the development of a safe and humane anesthesia procedure and techniques of long‐term physiological maintenance of the animal during surgery. The surgical anatomy was a challenge especially because of the extensive venous plexuses that invest the entire ear and adnexa. The corpus cavernosum carotidis and other small arterial networks course through this venous mass.

Sodium pentothal‐halothane anesthesia and careful physiological monitoring were determined to be adequate for long‐term maintenance during surgery and cochlear recording experiments. A specially designed surgical tank held the animal during the procedure. Immersion in water relieved the lungs of external pressure that ordinarily occurs, when the animal is out of the water, due to the flexible thorax. Thermoregulation was provided for by regulating the water temperature in response to the dolphin's core temperature. This arrangement also provided for underwater auditory stimulation and easy manipulation of the animal since dolphins with their lungs inflated are close to neutral buoyancy.

It was necessary to ligate the external and internal carotid arteries, neither of which supplies blood to the ear or brain. Hemostasis in the massive venous plexus could be achieved only by partial removal and subsquent application of oxycel and surgical cement to effectively dam off the area of the round window and other ear structures for electrical potential recording and experimental manipulations.

With this technique the round window of the cochlea was exposed. Fully anesthetized animals were maintained for periods up to 24 hours while electrophysiological measurements were being made. Some of the auditory measurements required further surgical manipulation of the auditory meatus, bulla, ossicular chain and other middle‐ear structures.
Development of the rat salivary glands. III. Mesenchymal specificity in the morphogenesis of the embryonic submaxillary and sublingual glands of the rat
Authors: Ball William D.
Published: June 2005

The parotid, sublingual and submaxillary buds of the embryonic rat can undergo typical morphogenesis in response to capsular mesenchyme from either the parotid or submaxillary‐sublingual rudiment. The submaxillary epithelium can be induced by embryonic bronchial mesenchyme to undergo limited morphogenesis, while the sublingual epithelium exhibits more extensive morphogenesis in response to the same stimulus. Pancreatic mesenchyme and jaw mesenchyme are essentially inactive in inducing the submaxillary epithelium, but can consistently stimulate morphogenesis of the sublingual rudiment at a relatively low level of complexity. Thus, the sublingual rudiment shows a less‐stringent mesenchymal requirement than does the submaxillary, and with both rudiments, lung mesenchyme is more effective than pancreas or jaw mesenchyme in supporting morphogenesis.
The inhibitory effects of Concanavalin A on the development of the amphibian embryo
Authors: Moran Denis
Published: June 2005

Concanavalin A exerts a reversible inhibition upon gastrulation and neurulation in the amphibian embryo. This inhibition depends on concentration and is attenuated when the embryonic capsules are left intact.
Incorporation of 3H‐thymidine in rhesus monkey (Macaca mulatta) embryos
Authors: Sawyer R. H. , Wilson D. B. , Anderson J. , Hendrickx A. G.
Published: June 2005

A procedure has been developed whereby cell proliferation during early embryogenesis of the monkey can be studied radioautographically following in vivo exposure to relatively small amounts of 3H‐thymidine.
Lysosomes and lysosomal enzyme activity in the regenerating planarian; Evidence in support of dedifferentiation
Authors: Coward S. J. , Bennett C. E. , Hazlehurst B. L.
Published: June 2005

The lysosomal enzyme acid phosphatase has been shown to increase in activity rapidly during the first 12 hours of cephalic regeneration in the planarian Dugesia dorotocephala. This increase was correlated with the cytological demonstration of lysosomes in dedifferentiating cells and the electron microscopical cytochemical localization of acid phosphatase in lysosomes. These findings are interpreted as being consistent with the dedifferentiation hypothesis for the origin of blastema cells.
Length, weight and secondary sex character development in male and female phenotypes in three sex chromosomal genotypes (XX, XY, YY) in the killifish, Oryzias latipes
Authors: Fineman Robert , Hamilton James , Chase Gary , Bolling David
Published: June 2005

Length and weight of medaka appeared to be influenced by sex hormone‐treatment and genotype. Hormone‐treated genotypes were significantly shorter in length and slightly lighter in weight than untreated genotypes. The degree of response to androgenic and estrogenic treatment appeared to be strongly influenced by genotype. Growth of XX fish was stunted more by androgenic treatment than by estrogenic treatment. Growth of XY and YY fish was stunted more by estrogenic than by androgenic treatment. Differences in the metabolism of sex hormones by the three genotypes might be responsible for the variation in response to androgenic or estrogenic treatment. Sex phenotype, a unique interaction between genotype and exogenous hormone‐treatment, strongly influenced secondary sex character development (relative papillary size and number).
Binding of antibody to LDH‐X by the mouse blastocyst
Authors: Bene Michelle , Goldberg Erwin
Published: June 2005

LDH‐X from spermatozoa can be demonstrated within the perivitelline space and zona pellucida of the preimplantation mouse embryo. Peroxidase reaction product is deposited in these areas of blastocysts incubated with rabbit anti‐LDH‐X IgG and then with peroxidase labelled goat anti‐rabbit IgG. Unfertilized ova do not bind antibody to LDH‐X.
Morphological substrates of conduction in the colonial hydroid Hydractinia echinata. I. An ectodermal nerve net
Authors: Stokes Darrell R.
Published: June 2005

Correlative light and electron microscope observations suggest that the colonial hydroid, Hydractinia echinata, possesses a single ectodermal nerve net in gastrozooid and dactylozooid polyps, and in the uppermost ectodermal sheet of the basal mat, but not in free stolon tips. Two distinct cell types comprise this nerve net — ganglion cells and sensory cells, the neurites of which characteristically possess microtubules and electron dense, membrane‐bound vesicles. The sensory cell body possesses an apical ciliary apparatus which distinguishes it from the ganglion cell type. Ultrastructural features of ganglion and sensory cells are presented in relationship to their distribution. Gastrozooids and the basal mat contain ganglion and sensory cells; dactylozooids contain ganglion cells primarily on the concave side of the polyp. Significantly, distinct bundles comprised of several neurites are found directly above the epithelio‐muscular cell processes of the gastrozooid and dactylozooid. Although synaptic junctions have not been found between ectodermal nerve cells and the muscle processes, they have been found bridging two nerve cells.
Investigations on the function and hormonal regulation of the anal appendices in Blennius pavo (risso)
Authors: Laumen Johannes , Pern Uwe , Blüm Volker
Published: June 2005

The appendices of the first and second anal fin spines of mature males of the mediterranean Blennid fish, Blennius pavo, produce a pheromone which attracts females of the same species. Evidence for this is provided by the observation that water from aquaria in which mature males have been kept is strongly attractive to female fish. However, aquarium water from females or from immature males, whose anal appendices are poorly developed, is without effect. Aquarium water from immature males that had been treated with luteinizing hormone at a concentration of 0.15 mg/g bodyweight, but not higher, is effective in attracting females. Such LH treatment leads to enlargement of the anal appendices and to a proportional increase in the behavioral reactions of female fish brought into contact with aquarium water from such treated males. Aquarium water from males whose anal appendices have been removed by surgery or cautery does not elicit behavioral reactions from female fish. Histological examination of the anal appendices reveals the presence of numerous tubular invaginations in the epidermis. It is conjectured that pheromone production is related to the proliferation and degeneration of epidermal cells which can be seen to occur in the tubular structures. The pheromone(s) appears to be produced phasically during spawning under the direct influence of hypophyseal gonadotropin.
DNA synthesis without mitosis in amputated denervated forelimbs of larval axolotls
Authors: Tassava Roy A. , Bennett Leo L. , Zitnik Gaylynn D.
Published: June 2005

Both forelimbs of axolotl larvae were amputated at the elbow and left limbs were immediately denervated. Both the left and right limbs of 4 larvae/day were examined for DNA synthesis (H3‐thymidine‐autoradiography) and mitotic index on days 1 to 7 post‐amputation. DNA synthesis was evident in both innervated regenerating, and denervated non‐regenerating limb stumps, on days 4, 5, 6, and 7. Mitotic index increased only in innervated limbs, beginning on day 5.
Ultrastructure of the development and subsequent breakdown of muscle in aneurogenic limbs (Ambystoma)
Authors: Tweedle Charles D. , Popiela Heinz , Thornton Charles S.
Published: June 2005

A study, mainly by electron microscopy, has been made on the forelimb musculature of Ambystoma opacum larvae following removal of the presumptive limb innervation in the embryo. In the aneurogenic limbs, early development and differentiation of striated muscle occurs at the same rate as in normal animals. At the time of nerve ingrowth into the normal limb, both myotubes and differentiated myofibers of small diameter are present. With the failure to make contact with nerves, the aneurogenic muscle does not advance beyond the early myofiber stage and soon (1–2 weeks) begins to show signs of atrophy. As has been described in studies of denervated adult muscle, the breakdown seems to be in two phases overlapping in time. In the first, a degenerative autolysis takes place, leading to loss of striation. There is dissolution of the Z bands, followed by disorder of the myofilaments. During this process there is evidence of fragmentation of the muscle fiber, both into nucleated and anucleate portions; waste sarcoplasm is thought to be discarded into the intercellular spaces. Interestingly enough, with the techniques used, no sign of lysosomes was noted and only a few macrophages were seen. The second phase of muscle breakdown is one with characteristics of atrophy, where single myofibers undergo gradual reduction in diameter. This process seems to take place by detachment of filaments from the periphery of the fibers and by their subsequent breakdown in the interfibrillary spaces. Late stages of muscle deterioration show large areas of cytoplasm containing scattered ribosomes, small vesicles, and a few mitochondria. The final picture is of densely stained irregular nuclei surrounded by a thin rim of cytoplasm; the intercellular spaces contain a considerable amount of fibrous material. The cartilage and skin of the aneurogenic limb appear normal even after the latest stages of muscle deterioration.
Forebrain localization of the spawning reflex response to exogenous neurohypophysial hormones in the killifish, Fundulus heteroclitus
Authors: Macey Michelle J. , Pickford Grace E. , Peter Richard E.
Published: June 2005

Stereotaxically placed electrolytic lesions were made in six areas of the forebrain of killifish, Fundulus heteroclitus. Lesioned fish were tested for their ability to respond to intraperitoneal injections of hog posterior pituitary suspension or synthetic arginine vasotocin, administered at doses that ensured occurrence of the spawning reflex response in unoperated controls. Only lesions that destroyed a major part of the nucleus preopticus severely impaired, or abolished, the spawning reflex response.
The chemical ecology of Biomphalaria glabrata (say): The effects of media homotypically conditioned by adult snails on the growth of juveniles
Authors: Thomas J. D. , Aram R. H.
Published: June 2005

Homotypically conditioned media (Hom. C.M.) produced by adult Biomphalaria glabrata weighing about 600 mg and fed on pure cellulose under bacteriostatic conditions at a density of one snail per 100 milliliter of standard snail water for three days significantly enhanced the growth of juveniles. Hom. C.M. produced under the same conditions by fasting snails that were previously fed on lettuce, also had a growth promoting effect but was less potent. The growth promoting factors have a molecular weight of 500‐104, and appear to act directly on the snails and not indirectly by influencing the food medium. The extent to which absolute growth rate is stimulated by the growth factors correlates well with decrements in the conductivity and calcium concentration of the media. Possible modes of action of the growth factors are discussed. They appear not to influence the relative weights of shell, or body and water content of the snails. It is suggested that the adaptive significance of the growth factors is to facilitate rapid increase in numbers of this gregarious and often fugitive species when environmental conditions are favorable.
Dedifferentiation and mitotic activity in amputated newt tails locally deprived of the spinal cord (Including a note on effects of amputation level on mitosis)
Authors: Donaldson Donald J. , Wilson Jack L.
Published: June 2005

The spinal cord of freshly amputated newt tails was displaced cranially by pushing several paraplast chips into the spinal canal with a glass needle. That part of the canal formerly occupied by the spinal cord was then packed with paraplast. Tails treated in this manner failed to regenerate, forming no more than a millimeter of new tissue with little or no cartilage and muscle. Dedifferentiation and early mitotic activity, however, was normal, indicating that the spinal cord exerts its effect on tail regeneration in the later stages. Amputation through the proximal region of a vertebra led to a significantly lower mitotic rate at four days than did amputation through the distal region, a situation contrary to the principle that during regeneration, elongation rate is generally faster from proximal than distal levels.
Experimental studies on a lethal gene (I) in the Mexican axolotl, Ambystoma mexicanum
Authors: Chung Hae‐Moon , Briggs Robert
Published: June 2005

1. Gene l is a recessive lethal factor found in the white strain of axolotls. Animals heterozygous for the gene are phenotypically normal. When mated with each other they give offspring 25% of which exhibit the lethal effects of the gene. 2. The l/l homozygotes develop normally to an advanced embryonic stage (Harrison stage 40) before the effects of the gene are first manifested. They then come to display a characteristic combination of abnormalities, including a disproportionately small head, small and poorly developed eyes, abnormal poorly developed gills, undifferentiated limb buds, and reduced overall growth rate. They may feed briefly, but soon stop and invariably die within a few weeks of the time of hatching. 3. The action of gene l has been analyzed by parabiosing mutant and normal embryos, and by grafting various organ primordia reciprocally between mutant and normal embryos. Parabiosis to normal embryos fails to correct the abnormalities of the mutants, although their survival may be somewhat prolonged. Grafts of mutant organ primordia (eye, limb, gill, pronephros, gonad, head) also invariably fail to show improved development or to survive on normal hosts; normal organ primordia develop normally on mutant hosts so long as the mutant survives.

These experiments indicate that gene l is a recessive autonomous cell lethal affecting all of the organ systems during late embryonic and early larval development.
Association of an ultraviolet irradiation sensitive cytoplasmic localization with the future dorsal side of the amphibian egg
Authors: Malacinski George M. , Benford Helen , Chung Hae‐Moon
Published: June 2005

Drastic alterations in neural morphogenesis can be induced by ultraviolet irradiation of the amphibian egg. The target area of U.V. was determined either by direct irradiation of various regions of the egg or by comparing the area of the U.V. hit with the location of the dorsal lip. Axolotl eggs which displayed easily recognizable gray crescents were employed for the direct irradiation experiments and albino axolotl eggs were used for a comparison of the U.V. sensitivity of the animal and vegetal halves of the egg. Marked frog eggs were employed to determine the relationship between the sensitive area and the site of formation of the dorsal lip. It was concluded that the dorsal marginal zone of the fertilized, uncleaved egg was the most sensitive area of the egg.

Ovarian homogenates provide a source of material for correcting, by microinjection, the effects of U.V.
Immunofluorescent localization of bovine acrosin
Authors: Garner Duane L. , Easton Marlys P. , Munson Mark E. , Doane Mark A.
Published: June 2005

Acrosin, a trypsin‐like proteinase, was localized in the acrosome of methanol‐fixed bovine spermatozoa by the indirect immunofluorescent technique. Anti‐acrosin immunoglobulin was obtained from a rabbit immunized with highly purified bovine acrosin. The results of agarose‐gel immunodiffusion analyses indicated that although the antibody was specific for the acrosomal enzyme, it cross‐reacted with ovine acrosin.
Distance chemoreception‐triggered avoidance behavior of the limpets Acmaea (Collisella) limatula and Acmaea (Notoacmea) scutum to the predatory starfish pisaster ochraceus
Authors: Phillips David W.
Published: June 2005

In a flow of normal seawater, populations of the limpets Acmaea (Collisella) limatula and Acmaea (Notoacmea) scutum on a horizontal surface moved upstream (positive rheotaxis). In contrast, when the scent of the predatory starfish Pisaster ochraceus was present in the water current, populations moved downstream. On a vertical surface in a flow of normal (control) water, the populations moved strongly upward in the dark (negative geotaxis) and away from light (negative phototaxis). In the presence of Pisaster scent, negative geotaxis was increased both in the light and in the dark. Negative geotaxis appeared to be a stronger response than negative rheotaxis in the presence of Pisaster scent, since limpets on a vertical surface with starfish scent in a current directed downward from above still moved up. A sample of limpets tested repeatedly in the presence of Pisaster scent was found to contain individuals differing significantly in the number of positive responses evoked and the vertical distance traveled during a response. The adaptive significance of the responses is discussed.
Synthesis of soluble protein in oocytes of Xenopus laevis
Authors: Heidemann Steven R. , Townsend Janis , Tompkins Robert
Published: June 2005

Oocytes of five stages of development were isolated from ovaries of Xenopus laevis and allowed to take up radioactive amino acids. After six hours of labeling the amount of label incorporated into perchloric acid precipitable material from the soluble oocyte fraction and the specific activity of the label free pool was determined. From these figures an estimate of the rate of protein synthesis was calculated. Labeled soluble protein from each oocyte stage was analyzed by electrophoresis on SDS polyacrylamide gels. The gel was dried and autoradiographed to determine the qualitative pattern of soluble protein synthesis during various stages of oogenesis.

Our results indicate that no significant differences exist in the rate of protein synthesis among any of the stages of oogenesis investigated. The qualitative pattern of soluble protein synthesized during the labeling period is similar among the oocyte stages. Moreover, this qualitative pattern of soluble protein synthesis is the same as the pattern of soluble protein accumulated up to that time during oogenesis.

These results suggest a stable synthesis and accumulation of maternal protein products during Xenopus oogenesis, in marked contrast to the results that have been reported for RNA synthesis during oogenesis in Xenopus. Our results are discussed in terms of the present understanding of the process of maternal information accumulation.
Antibody‐mediated inhibition of immune responsiveness in baby chicks
Authors: Seto Frank
Published: June 2005

An experimental model for the analysis of antibody‐mediated regulation of specific immune responsiveness in chickens is described. Chick embryos and day‐old chicks were passively administered homologous serum with high anti‐mouse erythrocyte (MRBC) activity and then tested for immune responsiveness to MRBC several weeks later. Compared to the untreated controls, the hemagglutinin titers of experimental birds were obviously depressed for 2 to 3 weeks but near normal by the 4th week. The inhibitory property of homologous serum appeared directly related to the anti‐MRBC activity; serum samples collected on day 1 and 2 after immunization were ineffective and low in specific activity, whereas those collected after the 3rd day were progressively more inhibitory as the anti‐MRBC activity increased.
Initiation factor distribution in Xenopus laevis eggs
Authors: Garrison N. E. , Kaulenas M. S.
Published: June 2005

The distribution of activity similar to that of one of the initiation factors (1F2) was determined as a function of developmental stage in Xenopus laeviseggs and embryos. In vivo exposure of mature oocytes to hormone increases the total amount of detectable factor activity and facilitates the binding of 1F2‐like factor to ribosomes. The quality of factor bound is not correlated with polysome content.
A method for the chemical isolation of individual muscle fibers and its application to a study of the effect of denervation on the number of nuclei per muscle fiber
Authors: Cardasis Constance A. , Cooper George W.
Published: June 2005

A method is described for isolating intact, individual skeletal muscle fibers from glutaraldehyde fixed muscle. This method was conceived to eliminate the many limitations of determining muscle nuclear numbers in histological cross section. Glutaraldehyde fixed fibers are isolated by dissection while in a solution of low concentration guanidine in a borate buffer at high pH. Electron microscopy demonstrates that single fibers, isolated in this manner, are free of their microvasculature and connective tissue. Their basal laminas and the structures within them, including their satellite cells, are preserved.

This method is employed to determine whether changes in nuclear numbers occur within the basal lamina of individual muscle cells from 1 to 28 days following denervation of mouse gastrocnemius muscle. The total number of nuclei located within the basal lamina of individual muscle fibers (i.e. muscle and satellite cell nuclei) does not change after denervation. This rules out the possibility that additional nuclei are arising from an influx of cells outside the basal lamina or by mitotic division of nuclei within the basal lamina. However, the possibility of a change in the ratio of satellite cell nuclei, to muscle cell nuclei, is not eliminated.

Other possible applications of this isolation method are discussed.
The influence of thyroxine and acclimation temperature on glycogen reserves of the frog Rana pipiens
Authors: Packard Gary C. , Randall James G.
Published: June 2005

Leopard frogs were given daily injections of Na‐l‐thyroxine (2.0 μg/10 g body weight) for seven days, and control animals were given daily injections of the vehicle. During the period of treatment, half of the frogs were acclimated, in darkness and without food, at a constant temperature of 15°C, whereas the remainder of the animals were acclimated at 25°C. At the end of the seventh day, the frogs were killed by decapitation, and the glycogen concentration in samples of liver tissue and skeletal muscle was determined spectrophotometrically. Total hepatic glycogen of each frog subsequently was calculated from data on glycogen concentration and liver weight.

Treatment of leopard frogs with thyroxine had no apparent effect on hepatic glycogen reserves of animals acclimated at 15°C, but there was a striking reduction in glycogen content of livers from hyperthyroid frogs held at 25°C. Mobilization of hepatic glycogen in thyroxine‐treated animals held at 25°C presumably was secondary to a general stimulation of oxidative metabolism. Treatment with thyroxine had no effect on the concentration of glycogen in skeletal muscle of leopard frogs held at either of the acclimation temperatures used in this study.
Ingestion of colloid solutions by filter‐feeding mosquito larvae: Relationship to viscosity
Authors: Dadd R. H.
Published: June 2005

During ingestion tests of 1 to 3 hours duration with larval Culex pipiens, displacement of midgut contents was virtually nil for larvae filterfeeding in particle‐free water, whereas in various dilute colloid solutions displacement was rapid and comparable in rate to displacement in water containing particulate solids. For larvae in 0.01 to 0.1 % methylcellulose solutions or in 0.01 to 0.6% polyhall (polyacrylamide) solutions, having viscosities of approximately 1 to 1.5 or 1 to 3 centipoises, respectively, displacements increased with increasing concentrations from just detectable to maximal and remained maximally high for higher concentrations with viscosities up to 15 and 5 cp respectively. Progressively greater displacements were likewise observed with sucrose solutions of 4 to 20% and having viscosities of 1 to 1.5 cp, but at higher concentrations ingestion was poor because of severe osmotic damage to larvae. In 0.015% agar, which is about 10% more viscous than water, ingestion was virtually nil; but with a doubling of concentration to 0.03%, and with viscosity about 20% greater than for water, displacement was maximal. The correlation between increasing viscosity and increasing ingestion for methylcellulose, polyhall and sucrose implicates viscosity as a factor that may alter the mechanical properties of liquids so as to allow them to be ingested in bulk as readily as particulate solids. With agar, the viscosity difference between non‐ingested and maximally‐ingested concentrations was so small as to suggest that some other factor is involved in bringing about ingestibility, perhaps some property related to the molecular structure that at elevated concentrations of agar brings about the formation of gels.
Some additional observations relating to the mechanism of trypan blue induced teratogenesis
Authors: Hamburgh Max , Erlich Mark , Nathanson Ginger , Pesetsky Irwin
Published: June 2005

The mechanism and site of teratogenic action of trypan blue on mammalian embryos was reinvestigated. The experiments to be presented include (1) an analysis of the effect of trypan blue treatment on the morphology of the early mouse egg cylinder, (2) a demonstration of the effect of dye treatment on the enzyme acid phosphatase of yolk sac epithelium using histochemical procedures. Results obtained from these experiments indicate that trypan blue injected into mothers on day 7 of gestational age leads, within 12 to 24 hours after treatment, to dramatic abnormalities in 90–95% of egg cylinders examined. The frequency of gross malformations obtained by this treatment is considerably less when litters are examined at later stages of gestation. Acid phosphatase activity in yolk sac epithelium is depressed by the dye treatment, but there is no difference between enzymatically depressed yolk sacs of malformed embryos and yolk sacs surrounding normally appearing litter mates both obtained from trypan blue treated mothers. The hypothesis that trypan blue may exert its teratogenic effect by the direct exposure of egg cylinder stages to the dye, and that some of the egg cylinders affected may subsequently repair, is recommended for further testing.
The ontogeny of L‐α‐hydroxyacid oxidase isozymes in the mouse
Authors: Miles Joanna L. , Holmes Roger S.
Published: June 2005

Mouse liver hydroxyacid oxidase isozymes are present at low levels at birth and increase inactivity until day 13 after which HAOX‐B almost disappears and HAOX‐A i s reduced to approximately one half the maximum level in the adult. Kidney HAOX‐G appears near day 13 post partum and increases until adultl evels are reached, the female having four times the activity of the male. The pregnant female has significantly lower levels of HAOX‐A and HAOX‐B in the liver and higher activity ofHAOX‐B in the kidney. Developmental changes occur in the extent of epigenetic modification of mouse liver HAOX‐A during theearly neonatal period.