bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of thyroidectomy on testicular size and on the photorefractory period in the starling (Sturnus vulgaris L.)
Authors: Wieselthier Arthur S. , Van Tienhoven A.
Published: June 2005

Thyroidectomy of Starlings prior to exposure to long photo‐periods (17L:7D) resulted in a failure of testes to regress after an initial size increase. Thyroidectomy after four weeks of such exposure resulted in testicular regression followed by a second period of size increase. Testicular size was correlated with androgen secretion as indicated by yellowing of the bill. The effect of thyroidectomy was not due to increased gonadal sensitivity to gonadotrophins and not due to the requirement of the presence of the thyroid for regression per se. Presumably thyroidectomy results in higher gonadotrophin secretion.

Thyroidectomy did not affect the termination of the photorefractory period in the fall.

Thyroidectomized Starlings had higher body weights than controls.
Neuromuscular physiology of the strike mechanism of the mantis shrimp, Hemisquilla
Authors: Burrows Malcolm , Hoyle Graham
Published: June 2005

This study was planned to determine the neuromuscular basis of the very rapid strike movement, lasting only 5–10 ms, used by mantis shrimps to capture prey or defend themselves. The raptorial second thoracic append‐ages which are responsible for the strike action are unfurled by four muscles in the merus, two extensors and two flexors. All were found to be specialized for slow not fast contraction. The largest extensor muscle has a twitch time of 400 ms, reaches peak tetanic tension in 700 ms and takes one second to relax completely from this. It receives two “slow” and one “fast” motor axons distributed uniformly throughout the muscle. An overshooting spike occurs in each muscle fiber from the first activation of a train in the fast axon, but many seconds must elapse before the first muscle fiber will again respond with a spike. The smaller, medial extensor receives one fast axon which may give rise to overshooting spikes and an inhibitor whose effects appear to be minor; its muscle fibers are only weakly electrically excitable. The contraction and relaxation rates are slow, as are those of the medial flexor which receives two slow axons. The lateral flexor is divisible into two parts; a proximal region comprised of electrically passive fibers innervated solely by a slow axon and a distal region of spiking fibers innervated by a fast axon. The rapid strike action is explained not in terms of the rapid contraction of these muscles but in their operation of a mechanical device in the form of a “click‐joint,” described previously.
A comparison of the fine structure of late mouse blastocysts developed in vivo and in vitro
Authors: McReynolds Hal D. , Hadek Robert
Published: June 2005

The utrastructure of the in vivo developed late preimplantation mouse blastocyst has been compared with the fine structure of mouse blastocysts developed in vitro for 72 and 92 hours from the late two‐cell stage, as well as those grown in vitro for 26 hours from the late morula or early blastocyst stage. Very little difference was observed between the in vivo developed blastocysts and those cultured 26 hours in vitro. The differences between 72 and 92 hour‐embryos and the in vivo grown ones were significant. The in vivo specimen and those grown 26 hours in vitro had differentiated a layer of endoderm cells while the ones cultured in vitro from the two‐cell stage did not. Nuclear and cytoplasmic structures in the in vivo developed blastocysts are well‐differentiated while those of the embryos grown in vitro from the two‐cell stage were less advanced. Possible reasons for the apparently less differentiated stage of blastocysts developed in vitro from the two‐cell stage are discussed.
Photoperiodic control of fur growth and reproduction in the mink (Mustela vison)
Authors: Duby R. T. , Travis H. F.
Published: June 2005

The influence of light on fur growth and reproduction in the mink has been investigated. Exposure of kits and adults to 4L/20D (4 light hours/20 dark hours) after completion of the summer furring cycle accelerated the development of the winter pelage. Gradually increasing the length of the daily photoperiod after growth of the winter pelage had been completed also hastened the onset of the breeding season. An abrupt change from 4L/20D to 16L/8D either inhibited gonadal development or initiated gonadal atrophy. It was also noted that mink changed from a 4L/20D schedule to a 16L/8D schedule immediately after completion of the winter furring cycle failed to begin development of the summer pelage for 10 to 12 weeks. This observation suggests that a refractory period exists in the initiation of growth of the summer pelage. However, a similar experiment conducted after completion of the summer pelage showed that the animals responded immediately to decreased light by molting into the winter pelage. It was also noted that changes leading to the development of the summer pelage occurred concomitant with or slightly after the initiation of testicular regression, while gonadal recrudescence occurred after completion of the winter furring cycle. The significance of these observations in relation to possible hypophyseal mechanisms for their control is discussed.
Hemoglobin transitions in the bullfrog, Rana catesbeiana, during spontaneous and induced metamorphosis
Authors: Just John J. , Atkinson Burr G.
Published: June 2005

Electrophoretic separation of hemoglobins (Hb) during normal metamorphosis reveals larval Hb starting to disappear and adult Hb appearing during tail regression (Taylor and Kollros stage XXII). This transition is nearly complete by stage XXIV. Labeled amino acid incorporation studies demonstrate selective production of adult Hb at stage XXII, complete suppression of larval Hb by stage XXIII, and continued high levels of adult Hb production in one‐week‐old froglets. In circulating blood cells DNA synthesis begins to increase after forelimb emergence (stage XX), attains its height at stage XXII, and then declines. These results indicate that after the increase in thyroid hormone during normal metamorphosis, the first event in new blood cells is DNA synthesis. One week later these same new blood cells demonstrate a marked increase in adult Hb production.

In triiodothyronine (T3)‐induced metamorphosis there is measurable adult Hb production beginning 12 days after hormone treatment, indicating that thyroid hormone treatment can partially mimic the Hb transition of normal metamorphosis. This mimicry is not total because larval Hb continues to be produced and does not disappear, suggesting that other factors besides thyroid hormone may be involved in causing Hb transition during normal metamorphosis.
Morphogenetic movements in Salmo gairdneri Richardson
Authors: Ballard William W.
Published: June 2005

Uncoordinated movements of individual internal blastomeres of the pregastrular blastodisc are distinguished from true morphogenetic movements which later segregate the germ layers and establish the embryonic axis and its organs. These coordinated movements are described in detail for stages 7 through 10 on the basis of recorded drift of chalk dust implanted among the blastomeres, and of vital dye spots printed on the blastodisc. The movements of the chalk and of the living colored cells follow the same pattern but the chalk gives more precise information over a longer time span. There is no evidence of invagination, or in‐wheeling, or centripetal convergence. Most of the movements combine epiboly and convergence, but in different proportions varying with the depth of the cells and their distance from the blastodisc center. A line of chalk dust, implanted by needle thrust down the full depth of the blastodisc often divides into a superficial, chiefly epibolic, cloud of granules and a deeper one, convergent toward the axis. Particles from a single implantation site may become incorporated into a variety of organs and tissues, indicating that a fate map for Salmo must be three‐dimensional. The forebrain receives secondary contributions from the center of the blastodisc. Movements directly comparable to closure of neural folds are described during formation of the brain. The role of the germ ring is examined in detail. It does contribute to the mesoderm of the tail. Migration along it toward the axis involves only the hypoblast, through which cells move at very different rates.
Site of gene action in steel mice: Analysis of the pigment defect by mesoderm‐ectoderm recombinations
Authors: Mayer Thomas C.
Published: June 2005

Mice homozygous for the gene steel (S1) are black‐eyed white, anemic and sterile. Previous studies have shown that the pigment defect in the skin and hair results from a failure of the tissue environment to support pigment cell development. In an attempt to analyse more critically this block of pigmentation by the skin, recombinations were made between dermal mesoderm and epidermal ectoderm from normal and mutant 13 day mouse embryos. The re‐combined skin pieces were then grown for 14 days in the chick coelom and subsequently examined for melanocytes in the dermis and epidermis. The results demonstrated that both the mesodermal and ectodermal components of steel skin are adversely affected by the mutant gene. Steel dermis combined with normal epidermis failed to receive or support the development of melanoblasts from the normal component. Steel epidermis combined with normal dermis likewise remained free of melanocytes. No effect of the steel components on the development of pigmentation in the normal associated component was observed. These results are discussed in relation to the general inhibition of pigment in tissues other than skin of steel mice, and in relation to the interesting pleiotropic effects of the gene steel.
Changes in ion permeability and membrane potential during early echinoderm development: Electrophysiological and tracer‐flux determinations
Authors: Tupper Joseph T. , Powers R. Douglas
Published: June 2005

After fertilization the membrane potential of the Asterias embryo undergoes an approximately fourfold increase in internal negativity, as measured by intracellular microelectrodes. Our previous experiments have demonstrated that the ionic basis of the membrane potential in this embryo may be described by a simplified form of the constant field equation. Using this relationship, the present experiments illustrate that the relative permeability of Na to K (PNa/PK) may be determined at any time during the early cleavage of this embryo. The results of these experiments indicate a relative increase of PK as related to PNa as the mechanism responsible for the large change in membrane potential. This has been confirmed by independent determination of absolute values for PNa and PK by means of 24Na and 42K tracer‐flux analysis. Experiments carried out during early cleavage demonstrate a greater than two fold increase in K permeability (3.8 × 10−7 cm/sec to 9.5 × 10−7 cm/sec) with no concurrent alteration in Na permeability (0.1 × 10−7 cm/sec). PNa/PK in 15 minute and two hour post‐fertilized embryos is 0.03 and 0.01 respectively. Its magnitude is the same whether determined by the constant field assumption or from tracer‐flux analysis. These changes in ionic permeability occur on a time scale which is similar to that of increased metabolic and synthetic activities in other echinoderm embryos. A possible regulatory role in the early differentiation of this embryo is discussed.
Bud initiation in a non‐budding strain of hydra: Role of interstitial cells
Authors: Moore Linda B. , Campbell Richard D.
Published: June 2005

A non‐budding strain of Chlorohydra viridissima has been maintained by vegetative propagation and used to study factors which initiate budding. These hydra can be induced to bud by implanting small pieces of normal tissue into their columns. The cellular bases of the non‐budding phenotype and the bud induction were investigated by means of grafting, radio‐autography, and histological methods. No differences in the proportions or appearances of the cell types were observed between non‐budding and normal animals. However, induced buds have higher proportions of interstitial cells and their derivatives (nerves and nematoblasts) than do normal buds. Many of these interstitial cells and derivatives origihate from cells in the grafted implant, as demonstrated by using 3H‐thymidine labeled implanted tissue. Normal tissue from which interstitial cells have been previously removed will not induce buds in non‐budding hydra. We conclude that bud induction is mediated by migratory interstitial cells, and that the non‐budding strains of hydra owe their phenotype to a deficiency in those interstitial cell differentiation events which are necessary for bud initiation.
Developmental change in morphogenetic properties: Embryonic chick heart tissue and cells segregate from other tissues in age‐dependent patterns
Authors: Lesseps Roland J.
Published: June 2005

During animal development complex morphogenetic movements occur. If these movements are controlled by cell‐to‐cell adhesiveness, the latter should change during embryonic development. To test this possibility indirectly, heart cells or tissue fragments from chick embryos of one and one‐half to five days of incubation were paired in separate experiments with five‐day pigmented retina or neural retina or 36‐hour neural tube. The combinations were made either by fusing together intact tissue pieces or by aggregating mixed cell suspensions dissociated from tissue pairs. All fused pieces and aggregates were cultured for two and one‐half days. The heart cells and tissue fragments from young embryos (1.5–2 days of incubation) displayed a tendency to take up external positions when combined with neural tube. In contrast, heart cells and tissue fragments from older embryos (4–5 days of incubation) tended to take up internal positions when combined with neural tube. A similar result (young heart outside, old heart inside) was found when combinations of heart fragments were made with pigmented retina fragments. When heart fragments of varying developmental ages were fused with neural retina, the older heart pieces were completely covered by neural retina, whereas younger heart pieces were only partially, if at all, covered by neural retina. These results clearly indicate a change in morphogenetic properties of embryonic heart cells during these early developmental stages. The interpretation is that the heart cells are gradually increasing their cell‐to‐cell adhesiveness, passing from a less adhesive condition at one and one‐half days to a more adhesive condition at four days of incubation.
Intracellular localization of lens antigens in the developing eye of the mouse embryo
Authors: Van De Kamp Maarten , Zwaan Johan
Published: June 2005

The time of initial synthesis and the subsequent localization of the crystallins in the embryonic mouse lens were studied with antisera to adult mouse lens using the indirect fluorescent antibody technique. Fluorescence was first detected in a few centrally located cells of deeply invaginated lens rudiments (10.75 to 11 days of gestation), after a prolonged period of contact between presumptive lens and presumptive retina. The reaction usually was restricted to the basal cytoplasm of these cells. During formation of the lens vesicle in 11 to 11.5 day embryos a gradually increasing fraction of lens cells began to display fluorescence, throughout their cytoplasm. At the time of closure of the vesicle the reaction had spread throughout the posterior wall. After fiber elongation became distinct, the cells of the anterior lens epithelium began to fluoresce (11.5 days). All cells of the lens rudiment were uniformly fluorescent in 12 day embryos and in all subsequent prenatal stages. Reactions were never observed outside the lens. We concluded that the mouse crystallins are tissue specific proteins and that their production begins at a relatively late stage of lens morphogenesis.

When cells first showed fluorescence, they always had an elongated shape and their nuclei were in a basal position, close to the optic cup. A few hours later dividing cells became positive. Taking into account earlier found relations between cell shape and cell cycle phase, these observations may indicate that crystallin synthesis is initiated in the late S‐ or early G2‐phase of the cell cycle, and that embryonic lens cells retain the capacity to divide, even after acquiring large amounts of tissue‐specific structural proteins.
Chemical estimates of the RNA and DNA contents of the early mouse embryo
Authors: Olds P. J. , Stern S. , Biggers J. D.
Published: June 2005

DNA and RNA were extracted from mouse embryos at several stages prior to implantation. RNA was measured by extinction at 200 nm, and DNA by a fluorometric assay. The mean values of RNA in the ovulated oocyte, 1‐cell, 2‐cell, and blastocyst‐stage embryo were 0.554, 0.545, 0.396, 0.458, and 1.37 ng, respectively. The mean values of DNA in embryos at these same stages were 23.8, 29.3, 41.1, 155, and 439 pg. There was no significant rise in total RNA per embryo until after the 8‐cell stage. The amount of DNA in mouse spermatozoa was also measured, and found to be 3.8 pg per spermato‐zoan. From this study it is clear that the mouse oocyte and early embryo do not contain the large quantities of DNA, in excess of the diploid value, found in some amphibian and invertebrate eggs.
The development of isolated blastomeres in Bithynia tentaculata (prosobranchia, gastropoda)
Authors: Verdonk N. H. , Cather James N.
Published: June 2005

The development of isolated blastomeres, separated at the first and second cleavage has been studied. After separation at the first cleavage, one half‐embryo (CD) becomes swollen and balloon‐like and develops adult organs such as eyes, tentacles, shell, operculum, etc. The other half (AB) is much more compact and never develops these adult structures.

After separation on the alternate axis at the second cleavage to produce AD and BC halves, both halves could form all adult structures.

These results indicate an equivalent organizing capacity of the C and D quadrants contrary to most spiralians, such as Ilyanassa, where the D quadrant alone exerts the major organizational influence.

The experimental evidence is discussed in relation to the distribution of the cytoplasmic vegetal body, rich in RNA, which is passed to the CD blastomere in the polar lobe and then evidently equally distributed to C and D.
The adaptive response of the salt glands of adult mallard ducks to a salt water regime: An ultrastructural and tracer study
Authors: Martin B. J. , Philpott Charles W.
Published: June 2005

The salt glands of adult domestic mallards that had been maintained in three different physiological conditions were studied ultrastructurally. With adaptation to salt water conditions, the glands approximately doubled in size. This size increase appeared to result entirely from hypertrophy of the secretory cells which became a labyrinth of mitochondria filled basolateral interdigitations. The extent of the extracellular spaces and the complexity of the surface amplification was delineated by horseradish peroxidase and lanthanum salts. Tracer studies provided evidence that the junctional complexes may not always contain typical “tight junctions.” The ultrastructure of the gland is discussed in relation to the standing gradient osmotic flow hypothesis of Diamond.
Acetylcholinesterase in singly and multiply innervated muscles of normal and dystrophic chickens
Authors: Wilson B. W. , Linkhart S. G. , Nieberg P. A.
Published: June 2005

AChE isozymes, localization and activities of multiply innervated anterior latissimus dorsi (ALD), singly innervated posterior latissimus dorsi (PLD) and mixed semispinalis capitis muscles from 2, 6 and 12 week normal and dystrophic chicks were studied. AChE forms characteristic of chick embryo muscles were maintained in normal ALD and semispinalis muscles and lost in normal PLD muscles after two weeks of age. Dystrophic ALD and semispinalis muscles were similar in their AChE forms, localization and levels to their normal counterparts. Dystrophic PLD muscles exhibited embryo AChE forms, high AChE activity and AChE outside of the neuromuscular junctions within the sarcoplasm of the muscle fibers. The data suggest that tonic fibers of the chicken lack and that dystrophic fast twitch fibers are defective in a system that suppresses embryo AChE forms after hatching.
The pentose shunt in wild‐type and glucose‐6‐phosphate dehydrogenase deficient Drosophila melanogaster
Authors: Geer B. W. , Bowman J. T. , Simmons J. R.
Published: June 2005

Four‐day old Drosophila melanogaster homozygous or hemizygous for the glucose‐6‐phosphate dehydrogenase mutant allele, Zw−, possess slightly less than 10% as much glucose‐6‐phosphate dehydrogenase activity in whole‐fly homogenates as their wild‐type, Zw+, counterparts. The reduction of glucose‐6‐phosphate dehydrogenase activity in Zw− adults had no effect upon 6‐phosphogluconate dehydrogenase, phosphofructokinase, or malic enzyme activities. However, activities of the non‐oxidative pentose shunt enzymes were significantly greater in Zw− adults than in Zw+ adults. Radiotracer procedures indicate that the oxidative phase of the pentose shunt is blocked in Zw− adults. Zw− larvae grow less well on a defined minimal amino acid diet lacking fatty acids and whole nucleic acid than do Zw+ larvae, indicating that Zw− individuals have a lower biosynthetic capacity than Zw+ individuals.
A cytostatic factor in amphibian oocytes: Its extraction and partial characterization
Authors: Masui Yoshio
Published: June 2005

In mature unfertilized Rana pipiens oocytes a cytoplasmic substance exists that arrests mitosis at metaphase when injected into blastomeres. This is called “cytostatic factor (CSF)”. CSF is found to be inactive in fertilized eggs. CSF is extractable in a stable form with an extraction medium containing Ca++. In the absence of Ca++ it is inactivated during storage. CSF is not dialyzable and precipitates in ammonium sulfate solution between 20 and 30% saturation. Heat treatment at 55°C for 30 min inactivates CSF. RNAase treatment inactivates CSF, but protease treatment does not. Roles of CSF and Ca++ in oocyte activation at the time of fertilization are discussed.
Dorsal unpaired median insect neurons make neurosecretory endings on skeletal muscle
Authors: Hoyle Graham , Dagan Dani , Moberly Betty , Colquhoun William
Published: June 2005

This report presents results of a study in Schistocerca gregaria of large dorsal unpaired median neurons found previously in ganglia of several insects (Crossman et al., 171a; Hoyle, unpublished). Most of these neurons give off a single median neurite that makes a T‐branch, providing symmetrical left and right efferent axons. These axons emerge in ganglion nerve trunks and terminate in each of two nerves. They then travel to major skeletal leg muscles. One of the neurons supplies only the extensor tibiae (jumping muscle). The final branches of this neuron parallel the fast axon and supply muscle units that receive the fast axon only. All the muscle fibers in a unit are innervated (multiterminally) by the fast axon, but only a few receive terminals of the dorsal neuron in addition. The endings are of neurosecretory type, containing large numbers of dense core vesicles. Their function is unknown.
Response of the adult newt ventricle to injury
Authors: Oberpriller John O. , Oberpriller Jean C.
Published: June 2005

A study was made of the response of adult newt ventricle to injury. The major events in the repair process after wounding involve blood clot formation, coagulation necrosis, macrophagic activity, regenerative activity of heart muscle, and connective tissue formation. Light microscopic autoradiography indicated that there was a definite area of labeled cells in trabeculae adjacent to the wound, beginning at about ten days after injury. Electron microscopic autoradiography confirmed that myocytes containing myofibrillae underwent DNA synthesis. It was concluded that adult newt myocardium is capable of reacting to injury by the proliferation of myocytes at the wound area as indicated by both DNA synthesis and mitosis.
Acceptance and sustenance value of naturally occurring sugars fed to newly emerged adult workers of honey bees (Apis mellifera L.)
Authors: Barker Roy J. , Lehner Yolanda
Published: June 2005

Thirteen sugars were fed in 0.125, 0.5, and 2 M solutions in water and in 0.5 M sucrose: L‐arabinose, D‐xylose, D‐fructose, D‐glucose, D‐galactose, D‐mannose, lactose, maltose, melibiose, sucrose, trehalose, melezitose, and raffinose. Survival, water consumption, and sugar consumption were measured. No sugar equaled sucrose in acceptance or sustenance. Reduced survival seemed to be associated with aldoses that contain axial hydroxyl groups at C2 or C4 in a C1 pyran ring (mannose, galactose, or arabinose) even if they were in a sucrose solution that ensures feeding. Acceptance was correlated with survival, but whether low acceptance is a consequence or a cause of mortality was not established. When 0.5 M sucrose was supplied separately, bees showed a strong preference for the sucrose solution and were not harmed by small quantities of the other sugars.
The structural protein of reptilian scales
Authors: Baden Howard , Sviokla Sylvester , Roth Irwin
Published: June 2005

Previous studies of reptilian epidermis have shown that scales contain both a and feather fibrous proteins. The outer stratum (feather) and inner stratum (a) of snake (Boa constrictor) scales were separated and the tissue extracted with 6 M urea in 0.1 M Tris, pH 9.0, with 0.1 M mercaptoethanol. Following alkylation to the S‐carboxymethyl derivatives (SCM), the proteins were separated on the basis of their solubility at pH 4.5. X‐ray diffraction analysis indicated that pH 4.5 insoluble proteins represented the fibrous proteins while the soluble ones had the characteristics of matrix material. Disc electrophoretic patterns and amino acid analyses of the two types of fibrous proteins were different while those of the matrix proteins from both strata appeared to be very similar. The epidermal proteins of shell (feather) and extremity (a) skin from turtle (Pseudemys) were similarly isolated and shown to have different amino acid compositions. Although separation of the various components by differences in their solubility at pH 4.5 was not possible, a comparison of electrophoretic patterns suggested that the proteins extracted from the epidermis of the shell and extremity skin had different fibrous but similar matrix proteins. These studies indicated a strong similarity between reptilian scales and hair, where fibrous and matrix proteins are present and are separable on the basis of the solubility of their SCM derivatives. Although the a and feather fibrous proteins form filaments of very different size, it appears that they are associated with similar matrix proteins.
Effects of cell density on the expression of differentiation by chick embryo chondrocytes
Authors: Solursh Michael , Meier Stephen
Published: June 2005

In this report the effects of cell density on the expression of differentiation by chick embryo sternal chondrocytes is studied. Differentiation is simultaneously assayed in terms of the rate of synthesis of collagen and acid mucopolysaccharide and in terms of the distribution of newly synthesized acid mucopolysaccharide between the cells and the culture medium. Cell density is studied first in terms of the number of cells per plate and second in terms of the size of aggregates of cells. First, when cultures, started‐with 104 cells/60 mm dish, are studied over time, it is observed that the rate of synthesis of collagen and acid mucopolysaccharide increases faster than accountable for by the growth rate. Because conditioned medium placed on cultures grown in fresh medium can rapidly enhance mucopolysaccharide synthesis relative to the growth rate, it is suggested that conditioning of the culture medium might contribute in part to the observed rapid acceleration of the expression of differentiation with time in culture. Second, when cultures are started with small inocula so that large aggregates of cells form before cultures reach stationary phase, both the rate of synthesis of specialized products and the ability of cells to retain acid mucopolysaccharides is promoted. It is suggested that accumulated matrix might provide a microenvironment that itself promotes better expression of the cartilage phenotype.
Wound healing in Eisenia foetida (oligochaeta). 1. Histology and 3H‐thymidine radioautography of the epidermis
Authors: Burke Janice M.
Published: June 2005

When the eight most anterior segments of Eisenia foetida are removed the wound is provisionally closed by a plug of coelomocytes surrounding an everted or retracted esophagus. Usually within one to three days the wound is definitively covered by migration of the columnar cells from the adjacent epidermis over the coelomic plug. Epidermal basal and gland cells do not directly take part in wound epithelialization.

In the normal epidermis 2.3% of the cells incorporate 3H‐thymidine during a labeling period of one hour. The incorporation rate for the columnar cells is higher than that for the basal cells and the gland cells are not labeled. During the period of wound covering by the epidermis (the first three days after transection) the DNA synthetic rate for basal cells and columnar cells drops steadily in both the segment bordering the wound and for at least four segments posteriorly. At four and five days the labeling rate for the epidermis of the segment near the wound rises sharply to beyond the control levels (3.7%) then drops again abruptly at six to seven days (0.8%). Two to four segments posterior to the wound the incorporation rate remains at the low 3‐day level throughout the first week after transection.
Cell aggregation: Properties of cell surface factors from five species of sponge
Authors: McClay David R.
Published: June 2005

Aggregation factors isolated from the cell surface of five species of sponge are shown to be specific in their ability to enhance cell aggregation. Factors from Haliclona viridis, Haliclona variabilis, Tedania ignis, Homaxinella rudis, and Dysidea crawshayi each exhibit the species specific enhancing effect and have no such effect in heterospecific cell‐factor combinations. Radioactively labeled cell free supernatant materials are shown to bind selectively to homospecific cells suggesting that cells contain specific receptors for attachment of the aggregation mediating materials. Finally, in several heterospecific combinations there was an inhibition of cell aggregation. The inhibitory agent was separated from the enhancing factor chromatographically. After removal of the inhibitory substance, the enhancing factor was still active in promoting cell aggregation of the homospecific cells only.
Ultrastructural autoradiography and cytochemistry of the iodine‐binding cells in the ascidian endostyle
Authors: Dunn Ann D.
Published: June 2005

Thyroid‐like activity was investigated in the endostyles of Molgula manhattensis, M. occidentalis and Styela plicata. Animals were immersed in sea water containing 125I for one to 24 hours. Although electron microscopic autoradiography revealed an extracellular accumulation of silver grains associated with zone 8 in all three species and with zone 9 in two of them, intracellular accumulations were found only in zone 7. Within this zone in each of the three species, grains were present over the apical cell membrane, multivesicular bodies and the apical cytoplasmic matrix after brief exposure to 125I. After longer exposure, grains were also present over large dense bodies and more basal regions of the cytoplasmic matrix.

Certain features, suggestive of thyroidal functions, were observed in the cells of zone 7. These included morphological evidence for secretory and pinocytotic activities and cytochemical evidence both for peroxidase activity and for the presence of carbohydrate material which may represent a glycoprotein.

It is concluded that active binding of iodine is restricted to zone 7 in the endostyles of Molgula and Styela, where it occurs at both the apical cell membrane and within multivesicular bodies. Some of the iodinated product may be immediately passed into the lumen of the pharynx. The rest is stored intracellularly within multivesicular bodies and dense bodies of zone 7. Intracellular binding and storage of iodine are considered to represent primitive conditions preceding the evolution of the follicular structure of the thyroid gland.
Influence of diet on sugars found by thin‐layer chromatography in thoraces of honey bees, Apis mellifera L.
Authors: Barker Roy J. , Lehner Yolanda
Published: June 2005

Twelve sugars in 0.5 M solution in water and also in 0.5 M solution in 0.5 M sucrose were fed to newly emerged, caged honey bee workers. After 11 to 27 hours, the sugars of ice water extracts of degutted thoraces were promptly analyzed by thin‐layer chromatography.

Unlike published values for sugars in the hemolymph from healthy bees, trehalose was the predominant sugar in the thorax. Lesser amounts of glucose and only traces of fructose were found. Trisaccharides were found in the thorax after they were fed to bees.

Progress was made toward determining which nonsustentative sugars are toxic and which are not accepted. Galactosides seem toxic per se and not to be progenitors of toxic galactose. Galactosides and mannose gave no buildup of a particular sugar to indicate metabolic blockage. Starved bees and moribund bees with empty crops contained glucose but no trehalose. Analysis of thoracic sugars has potential value in diagnosis of bee poisoning.
Field experiments on sexuality in the freshwater sponge Spongilla lacustris. The control of oocyte production and the fate of unfertilized oocytes
Authors: Gilbert John J.
Published: June 2005

Gemmulated, female sponge was collected from nature on 10 November 1971 and then stored in the laboratory at 3°C in the dark. Pieces of this sponge were set out in the pond of origin on 29 May, 6 July, 10 August, and 14 September 1972 and on 16 May 1973. Oocyte production was observed in all sponges developing from the hatched gemmules about one week after implantation. The production of young oocytes ceased three or four weeks following implantation except in the sponges implanted on 14 September 1972, which continued to produce oocytes up to 6 November. This extended period of oocyte production was associated with and may be due to low water temperatures.

The study shows that oocyte production does not require an environmental stimulus specific to a particular time of year, for oocytes differentiated under conditions of increasing as well as decreasing water temperatures and day lengths. The control of oocyte production is probably endogenous and associated with gemmule hatching. The possible nature and the adaptive significance of this control mechanism are discussed.

Oocytes produced in sponges implanted after the normal sexual period in the pond were not fertilized. Such oocytes go through the normal growth sequence up to the end of the “grand accroissement” phase. Then they degenerate, ultimately releasing their stored yolk bodies into the mesenchyme.

All evidence indicates that this population of the species is dioecious.
Calls of different individual hens and the parental control of feeding behavior in young Gallus gallus
Authors: Cowan P. J. , Evans Roger M.
Published: June 2005

Selective food pecking by young domestic chiks to parental calls from different individual hens was demonstrated. Previous experience with a parental call paired with visual movement can decrease the number of food pecks to novel calls in testing as compared to the responses of chicks which have received either the parental call or visual movement alone in training. Selective food pecking to parental calls appears to assist in the maintenance of the family unit.
Effects of grouping on sexual receptivity in female hamsters
Authors: Lisk Robert D. , Reuter Lawrence A. , Raub Jeffrey A.
Published: June 2005

Female hamsters maintained in groups of 4 to 12 animals continue to show four‐day ovulatory cycles. However, when placed with males on the evening of proestrus, only 40% of these grouped females mate. Ninety‐five per cent of females caged singly or in groups of two, mate in less than ten minutes when placed with males on the evening of proestrus. Thus, grouping of female hamsters blocks reproduction in some individuals through a behavioral mechanism which does not apparently affect the ovulatory cycle. Receptivity cannot be reinitiated in such animals by administration of exogenous progesterone on the afternoon of proestrus.
Establishment of cleavage furrows by the mitotic spindle
Authors: Rappaport R. , Rappaport B. N.
Published: June 2005

The purpose of this investigation was to determine the capacity for furrow establishment of the mitotic spindle in several kinds of dividing animal cells. To this end the cell shape was altered so that equatorial surface was brought in contact with the spindle and its normal geometrical relation with the asters changed. In flattened Tripneustes gratilla eggs, furrows formed at the tips of deeply cut notches that impinged upon the spindle area. In Echinarachnius parma eggs, furrows formed at the tips of deeply cut notches and also at the margins of perforations that straddled the spindle. The distance separating the perforations was less than the normal spindle diameter. In flattened, dividing cultured newt (Diemictylus viridescens) kidney cells furrows formed in equatorial surface that was pushed inward far enough to displace the metaphase chromosomes. These results appear to indicate that the mitotic spindle of animal cells can establish furrows. We speculate that the actual role played by the spindle in normal cytokinesis depends upon the relative sizes of the asters and the spindle and upon the normal distance between the spindle and the equatorial surface.
Mayer waves in the circulation of a teleost fish
Authors: Wood Chris M.
Published: June 2005

Regular oscillation in arterial blood pressures identical to mammalian Mayer waves were recorded in unanaestetized trout (Salmo gairdneri). The waves were associated with hemorrhage, were caused by fluctuations in systemic vascular resistance, and were sometimes accompanied by fluctuations in cardiac output of opposite phase. Alpha‐adrenergic blockade eliminated the phenomena; muscarinic cholinergic blockade was ineffective. The existence of Mayer waves provides evidence for a nervous control of vasomotor tone in teleosts.
Sound and sound emission apparatus in puerulus and postpuerulus of the western rock lobster (Panulirus longipes)
Authors: Meyer‐Rochow V. Benno , Penrose John D.
Published: June 2005

Sounds and sound emitting structures of larval rock lobsters are compared with those of juvenile and adult. The rasping sound, typical of disturbed juveniles and adults, is not produced by the puerulus, although file and plectrum are developed. The sound is, however, heard in the postpuerulus. Sound characteristics vary with age, individual and species, and therefore are of little value to spiny lobster taxonomy.
Avian scale development. III. Ultrastructure of the keratinizing cells of the outer and inner epidermal surfaces of the scale ridge
Authors: Sawyer Roger H. , Abbott Ursula K. , Fry Greta N.
Published: June 2005

Ultrastructural features of keratinization differ for the inner and outer epidermal surfaces of developing avian scales. Only the alpha stratum develops along the inner scale surface, and it is retained after hatching and is still present in adult birds. The cells of the alpha stratum are characterized by lipid droplets, multigranular bodies, and peripherally located keratohyalin granules. In contrast, the epidermis of the outer scale surface develops both alpha and beta strata. The alpha stratum is lost soon after hatching and only the beta stratum is found in the mature bird. Bundles of 30 Å filaments fill the cells of the beta stratum and keratohyalin granules are not present. The outermost peridermal and subperidermal cell layers develop along both epidermal surfaces of the scale. These two cell layers are characteristic of the embryonic period and are lost at the time of hatching.
Avian scale development. IV. Ultrastructure of the anterior shank skin of the scaleless mutant
Authors: Sawyer Roger H. , Abbott Ursula K. , Fry Greta N.
Published: June 2005

Scales do not form on the legs and feet of the scaleless mutant chicken, and consequently, the skin in these regions remains soft and pliable, similar to that covering the rest of the body. By 17 days of embryonic development, both the peridermal and subperidermal cell layers have developed along the surface of the anterior shank epidermis. Subsequently, the scaleless epidermis cornifies, producing an alpha stratum characteristic of the inner epidermal surface of normal scales. The cells of the alpha stratum elaborate lipid droplets, multigranular bodies, and peripherally located keratohyalin granules. The beta stratum found along the outer epidermal surface of normal scales never develops.
Regeneration of the forelimb in adult hypophysectomized Notophthalmus (Diemictylus) viridescens given embryonic or adult chicken anterior pituitary extract
Authors: Liversage Richard A. , Fisher Kenneth R. S.
Published: June 2005

In absence of the anterior pituitary gland, limb and tail regeneration does not occur in the adult newt Notophthalmus (Diemictylus) viridescens. Sixty‐five adult newts were included in this work which was designed to test to what degree a hypophysectomized newt can regenerate its forelimb when given daily injections of fresh adult or stored (−20° C)‐thawed embryonic or adult chicken anterior pituitary gland extract. Injections were begun seven days after hypophysectomy (to minimize further the titres of residual circulatory hormones) and concomitant amputation. The results are based on three experimental, one control and one sham series.

In 40 out of 45 cases in Experiments C, D, and E, limb regeneration ensued for 25–30 days post‐amputation (until fixation). However, in the Experiment E newts, which were given embryonic chick pituitary extract, the regenerates were less advanced than those seen in the animals of Experiments C and D, given adult chicken pituitary extracts. Possible explanations for the differences in results are discussed.

The results show that forelimb regeneration and survival in our hypophysectomized animals were due to extracts of embryonic or adult chicken anterior pituitary glands; presumably, these extracts contained the essential hormones. On the basis of our newt bio‐test system, 15–18 day chick embryo and adult chicken anterior pituitary extracts (hormones) are not species specific. Freezing and storage of extracts at −20° C for up to three months before thawing and use apparently does not appreciably affect their hormonal activity.
Neuromuscular analysis of closing in the dimorphic claws of the lobster Homarus americanus
Authors: Govind C. K. , Lang Fred
Published: June 2005

The mechanical and electrical activity of the closer muscle is compared in the cutter and crusher claws of the lobster Homarus americanus. Two excitor axons innervate the closer muscle. In the cutter the fast axon produces twitch contractions in response to single stimuli while its counterpart in the crusher gives twitches only to paired stimuli. The twitches fatigue more rapidly in the cutter than in the crusher. The slow axon in both claws produces tonic contractions which are fatigue resistant. The electrical events in the muscle fibers correlate closely with the mechanical activity. Thus the cutter fast EPSPs show poor facilitation and fatigue rapidly while the slow EPSPs have high facilitation values and are less prone to fatigue. The slow and fast axon EPSPs in the crusher are qualitatively similar to their counterparts in the cutter. In both claws the postsynaptic response was considerably enhanced by paired stimuli.
Intracellular actions of 5‐hydroxytryptamine on the bivalve myocardium. II. Cyclic nucleotide‐dependent protein kinases and microsomal calcium uptake
Authors: Higgins William J. , Greenberg Michael J.
Published: June 2005

The effects of cyclic AMP, cyclic AMP‐induced phosphorylation, and 5‐hydroxytryptamine (5HT) on calcium uptake by bivalve heart microsomes were investigated. Cyclic AMP‐dependent and cyclic GMP‐dependent protein kinases were purified from Macrocallista nimbosa ventricles. The cyclic AMP‐dependent preparation readily phosphorylates myocardial cell proteins in both the soluble and microsomal fractions. The cyclic AMP‐mediated phosphorylation of microsomal protein augments microsomal calcium uptake; but 5HT and cyclic AMP also induce a similar increase directly. The protein kinase activity indigenous to the microsomal preparation was not increased by cyclic AMP.

In many molluscan ventricles, 5HT increases intracellular cyclic AMP and simultaneously enhances muscle contractility by altering the amount of intracellular calcium available for contraction. Therefore, if cyclic AMP acts as a second messenger and mediates the effects of 5HT, the nucleotide should augment, directly or indirectly, the amount of membrane associated calcium. This study suggests that cyclic AMP can mediate 5HT action either by the activation of a cyclic AMP‐dependent protein kinase, or by a direct modification of the amount of membrane associated calcium.
The caecilian ear
Authors: Wever Ernest Glen
Published: June 2005

A study of the ear and its responses to acoustic stimuli was carried out in two caecilian species, Geotrypetes seraphini and Dermophis mexicanus. There is no external ear opening or tympanic membrane. The middle ear mechanism consists of a single element, the stapes, with its footplate in the oval window and a headpiece extending anterolaterally to the quadrate. The inner ear contains a single auditory endorgan, the amphibian papilla, somewhat similar to this organ in anurans. The mode of stimulation by sounds, however, involves a reentrant fluid circuit as in certain of the reptiles.

In terms of the electrical potentials this ear is rather uniformly sensitive, though in low degree, to tones over the low‐frequency range.
Autoradiographic study of mouse spermatozoan arginine‐rich nuclear protein in fertilization
Authors: Kopečný Vaclav , Pavlok Antonín
Published: June 2005

General labeling of ripe mouse spermatozoa was obtained two weeks after six injections of L‐arginine‐5‐3H monohydrochloride, administered within two days. Besides tail labeling a very intensive nuclear labeling was obtained. It is presumed that this nuclear labeling represents almost exclusively tritiated arginine incorporation into basic nuclear protein.

Mouse oocytes were fertilized in vitro with such labeled spermatozoa. It was found that the nuclear label is lost very early during male pronucleus formation, probably concomitantly with sperm chromatin decondensation. This might indicate total loss of the basic spermatozoal nuclear protein before male genome activation.
Influence of season, photoperiod and thermal acclimation on the panting threshold of Amphibolurus muricatus
Authors: Heatwole Harold , Firth Bruce T. , Stoddart Helen
Published: June 2005

The panting threshold of Amphibolurus muricatus progressively elevates with increasing acclimation temperature. It is also elevated by long (16L:8D) photoperiod in comparison to values obtained under constant photic conditions or short photoperiods. There is a seasonal cycle (higher thresholds in the austral summer than in other seasons) which is independent of shortterm thermal acclimation or photoperiod. A fluctuating temperature regimen of eight hours at 6°C and 16 hours at 26°C under constant light resulted in a panting threshold intermediate between values for animals acclimated at constant 5°C and those acclimated at constant 26°C.