bluuebunny/crossref_metadata_2025 huggingface dataset:
Locomotion of bluefish
Authors: DuBois Arthur B. , Cavagna Giovanni A. , Fox Richard S.
Published: June 2005

Pressures previously measured on the body surface of swimming bluefish were resolved into their backward vectorial components to allow calculation of profile drag. It was 0.18 kg at a speed of 1.8 m/sec. Tangential drag was calculated as if for a thin plate of an area equal to that of the fish. It was 0.08 kg at 1.8 m/sec. Net drag, 0.26 kg, was the sum of profile and tangential drag.

Thrust and drag also were calculated from the changes of acceleration measured during steady swimming, assuming that thrust took place only during the acceleration phase, whereas drag occurred during both acceleration and deceleration. This drag was 0.08 kg at a speed of 1.1 m/sec. It is compatible with the drag of 0.26 at 1.8 m/sec calculated from profile and tangential drag provided drag varies as the square of velocity.

The force required to produce maximal acceleration was measured during a scare. It was calculated to be 6.9 kg at a peak acceleration of 3 g.

The compression strength of the vertebrae was found to be approximately 20 kg per cm2, or roughly three times the force encountered during maximal acceleration. This safety factor of 3 would be reduced when the back was curved, or if opposing groups of muscles were under tension.

The finding that a bluefish can accelerate at 3 g and that the vertebral column is strong enough to withstand this force indicates that the muscles and body structure of a bluefish would be able to withstand the force of gravity if the fish were otherwise equipped for terrestrial life. This fish may have evolved these strengths simultaneously with land animals. It is speculated that other fish may have evolved some degree of strength to overcome inertia and drag during aquatic locomotion, and this evolution may have been a prelude to terrestrial locomotion.
Furrowing in altered cell surfaces
Authors: Rappaport R.
Published: June 2005

Understanding the process which establishes the cell division mechanism requires analysis of the role of the responding surface as well as that of stimulatory subsurface structures. Cell surface was altered by the expansion which occurs during exovate formation. Exovates appear on the surface of fertilized Arbacia lixula, Paracentrotus lividus and Echinarachnius parma eggs in response to extreme flattening. They result from cytoplasmic outflow initiated in a very restricted portion of the egg surface. Observations of the formation process in pigmented A. lixula eggs revealed that the original surface may be expanded about 100‐fold as the exovate swells. When exovates formed 15–30 minutes after fertilization contain the mitotic apparatus, they divide synchronously with flattened controls. If nucleated exovates are established after the beginning of first cleavage, furrows appear in ten minutes. Exovates established after the beginning of second cleavage develop furrows four minutes after the entrance of the mitotic apparatus. Cytoplasm beneath damaged exovate surfaces sometimes develops partial constrictions independently of the surface in the plane the furrow would have occupied. These results suggest that normal surface structure is unnecessary for furrow establishment and function.
Effect of temperature on spermatogenesis, on the production and action of androgens and on the ultrastructure of gonadotropic cells in the lizard Anolis carolinensis
Authors: Pearson Anita K. , Tsui Hing Wo , Licht Paul
Published: June 2005

Adult male lizards (Anolis carolinensis) were kept at either 31° or 20°C for 11 weeks starting December 4, and the activity of the pituitary‐gonadal axis was monitored by examination of pituitaries, testes, androgen target organs and plasma testosterone levels.

The gonadotropic cells of both thermal groups were stimulated to secrete for approximately seven weeks. Thereafter, the cells of 31°C animals indicated reduced secretion and increased granule storage, while those at 20°C became hyperactive. Testes enlarged at both temperatures: testicular enlargement at 31°C was due to active spermatogenesis and sperm production, whereas at 20°C, gametogenesis was largely blocked at the spermatocyte level, and enlargement was due to accumulation of cells, growth, and hydration. Leydig cells were larger and more numerous at 31° Epididymal and kidney tubules (androgen target organs) increased in diameter and epithelial height at both temperatures, but responses were markedly greater at 31° Also, male‐male aggressive behavior occurred only at the higher temperature; dominant lizards had slightly higher testosterone levels than subordinates. In contrast, plasma testosterone levels were consistently higher (> 2‐fold) at 20°.

Thus the production of gonadotropins in Anolis is stimulated at 20° in late winter, and these hormones promote androgen production but not spermatogenesis. The high androgen level at 20°C evokes only a limited response in epididymis and renal sex tubules, and it neither inhibits the gonadotropic cells of the pituitary nor produces aggressive behavior. These results demonstrate that constituent processes in the pituitary‐gonadal system have different sensitivities to temperature and that thermal effects may be misinterpreted by standard histological or histometric analysis of gonads and accessory sexual structure.
Genome size in some reptiles
Authors: Olmo Ettore
Published: June 2005

The nuclear DNA content was studied histophotometrically in 49 reptilian species. The results obtained indicate that species of three orders show DNA values falling within similar variability range.
Adenosine 3′, 5′ ‐monophosphate, morphogenetic movements and embryonic neural differentiation in Pleurodeles waltlii
Authors: Wahn Harvey , Lightbody Laurace Townsend , Tchen T. T. , Taylor John D.
Published: June 2005

Evidence is presented for the following hypothesis dealing with dibutyryl‐c‐AMP induction of neural differentiation in Pleurodeles waltlii embryos: (1) Dibutyryl‐c‐AMP induces the determination for neural differentiation. (2) Additional dibutyryl‐c‐AMP is not needed for cytodifferentiation. (3) Cytodifferentiation of induced cells can only take place after morphogenetic movements (in vivo) or extensive cell migrations (in vitro). It is suggested that cell migrations, both in vivo and in vitro, lead to the separation of the induced cells from one another or from unidentified inhibitory cells.
Effect of dithiothreitol on meiotic maturation of mouse oocytes in vitro: Dependence of the effect on N6,O2′‐dibutyryl adenosine 3′,5′‐cyclic monophosphate
Authors: Wassarman Paul M. , Turner Pamela E.
Published: June 2005

The inhibitory effect of dithiothreitol on meiotic maturation of mouse oocytes in vitro is a function of the intracellular dibutyryl cyclic AMP concentration. Inhibition of nuclear (germinal vesicle) breakdown by dibutyryl cyclic AMP is reversed upon transfer of oocytes to plain culture medium, where‐as, transfer to medium containing dithiothreitol results in continued inhibition. Dithiothreitol significantly enhances the effectiveness of dibutyryl cyclic AMP as an inhibitor of meiotic maturation. These results suggest that the reported effect of sulfhydryl reducing agents on membrane dissolution and reconstitution, in both meiotic and mitotic cells, may be attributed to their influence on intracellular levels of cyclic AMP.
An analysis of MP gene affected morphogenesis in Tetrahymena pyriformis, syngen 1, (Species 1) ciliates
Authors: Kaczanowski Andrzej
Published: June 2005

The recessive mp gene in syngen 1 (Species 1) of Tetrahymena pyriformis results in a characteristic set of abnormalities of the adoral membranelles, commonly including some extra membranellar segments (Kaczanowski, '75). The abnormal pattern is produced in about 10% of dividing cells, compared to 80% of cells undergoing oral replacement. Thus the percentage of abnormal cells increases during prolonged stationary phase. Abnormal oral replacement arises primarily from a separation of two kinetosomal fields: the field of kinety no. 1 (the K‐1 field), and the anterior field originating from the displaced undulating membrane. Both sites of proliferation appear also during wild type morphogenesis, but they fuse early to form one integrated field (Frankel, ′69). The prolonged separation of the subfields in mp/mp cells results in a separate assembly of adoral membranelles; however, the independently developing membranelles of the two subfields are united later to produce a single oral apparatus. A single gene‐dependent factor apparently alters some property of the cortical layer, which in turn is responsible for a reduced integrity of the oral replacement primordium.
Role of gill Na+ + K+ ‐dependent ATPase in acclimation of blue crabs (Callinectes sapidus) to low salinity
Authors: Towle David W. , Palmer Gloria E. , Harris John L.
Published: June 2005

Male blue crabs (Callinectes sapidus Rathbun) were acclimated to salinities of 5 and 34 o/oo. Microsomal preparations of gills from these animals possessed Na+ + K+‐dependent ATPase specific activities of 2.33 ± 0.11 and 1.29 ± 0.11 μmoles Pi min per mg protein respectively, implicating the Na+ + K+‐dependent ATPase in the previously recognized ability of the blue crab to maintain high hemolymph sodium levels in low salinity environments. The specific ATPase activity of gill microsomes increased significantly within two and one‐half hours after transfer of crabs from high to low salinity, prior to stabilization of hemolymph sodium levels. The ATPase isolated from crabs acclimated to the two different salinities were both highly sensitive to ouabain, and required either K+ or NH4+ as well as Na+. Sodium‐dependent phosphorylation of both enzymes was blocked by K+ or NH4+. Polyacrylamide gel electrophoresis of the sodium dodecyl sulfate‐solubilized ATPases revealed one band of radioactivity in each case, with an apparent molecular weight of 104,000. The ability of NH4+ to serve as an effective counterion supports the hypothesis that, in blue crabs acclimated to low salinity, Na+ uptake may be coupled to NH4+ excretion.
Abnormal morphogenesis of feather structure and pattern in the chick embryo integument. I. Macroscopic description
Authors: Brotman Harris F.
Published: June 2005

The development of feathers in embryos from a profusely feathered line derived from a homozygous scaleless mutant stock was compared with that of embryos from a standard White Leghorn stock. The time of appearance of feather primordia, their structure and their arrangement all were altered in mutant embryos. Unit structures ranging in size from hillocks of 300 μ diameter (the size of normal primordia) to ridges 8 mm long were found in varying numbers in the different tracts of the mutant embryos. The hexagonal pattern characterizing feather primordia in normal embryos was disrupted in scaleless high line embryos. Differential growth and morphogenetic sculpting, as evidenced by the appearance of clefts, generate the form of and subdivide the variably shaped unit structures of the mutant as they elongate.

Selection for high feather number was successful in dramatically increasing the total amount of feathering but the absence of coordinate controls of pattern and feather structure development led to the aberrant arrangement of tracts and of structures within the tracts. The basic pattern thus appears to have been destroyed by the scaleless mutation, and the alteration of the phenotype accomplished by selection has not apparently restored its control.
Natural hybridization between parthenogenetic and bisexual lizards: Detection of uniparental source by skin grafting
Authors: Cuellar Orlando , McKinney Charles O.
Published: June 2005

Skin grafting evidence is used to directly identify the unisexual parent of natural hybrids produced between the bisexual species Cnemidophorus inornatus and the unisexual Cnemidophorus neomexicanus.

Reciprocal grafts transplanted among three suspected hybrids between Cnemidophorus inornatus and Cnemidophorus neomexicanus are rejected as well as grafts from the hybrids to C. neomexicanus, indicating that the hybrids are each genetically different from each other and that C. neomexicanus has the ability to reject foreign grafts.

Allografts among C. neomexicanus and xenografts from C. neomexicanus to the hybrids are not rejected, indicating that C. neomexicanus is genetically homogeneous and that the hybrids possess genomes genetically identical to C. neomexicanus.

Electrophoretic analysis of the hybrids and their probable parents supports the evidence obtained from skin grafting that C. neomexicanus is one of the parents, and suggests that C. inornatus, rather than C. tigris, is the bisexual parent.

Chromosome spreads obtained from the hybrids reveal a triploid number of 69, a number consistent with their presumed origin from unreduced diploid ova (2N =46) from C. neomexicanus and haploid sperm (N = 23) from C. inornatus.

Preliminary evidence is presented of the first hybrids known between Cnemidophorus inornatus and Cnemidophorus uniparens. Histological examination of the testes suggests that these hybrids are sterile.

Included is a list summarizing all known hybrids between bisexual and unisexual species of the genus Cnemidophorus.
Ionophore A23187 induces acrosome reactions in sea urchin and guinea pig spermatozoa
Authors: Summers R. G. , Talbot P. , Keough E. M. , Hylander B. L. , Franklin L. E.
Published: June 2005

Ionophore A23187, in the presence of extraceullular Ca+2, induces a morphologically normal acrosome reaction in sperm of the sea urchin and precocious acrosome reaction and activation of guinea pig sperm. Increased membrane permeability to Ca+2 is responsible for initiating the acrosome reaction in both sea urchin and guinea pig sperm. In sea urchin sperm, the permeability changes is brought about by egg jelly, whereas in the guinea pig sperm it accompanies capacitation.
The oral apparatus ofTetrahymena pyriformis, strain WH‐6. III. The binding of3H‐cytochalasin B by the isolated oral apparatus
Authors: Gavin R. H.
Published: June 2005

The binding of tritium‐labelled cytochalasin B by the isolated oral apparatus ofTetrahymena pyriformis, strain WH‐6, syngen 1, was investigated. Equilibrium binding studies revealed approximately 1.4 × 105cytochalasin B binding sites per oral apparatus. A Scatchard plot indicates a single class of binding affinities with an association constant of 105liters/mole. Rapid release of oral apparatus‐bound cytochalasin B occurred when oral apparatuses were washed and resuspended in 1 mM TRIS without cytochalasin B. Because cytochalasin B binding to oral apparatus microtubular protein was not detected, microtubules are probably not the cytochalasin B binding site. The probable nature of the cytochalasin B binding site within oral apparatus is discussed.
Biochemical changes in temperature‐activated statoblasts of an ectoproct bryozoan
Authors: Black Robert E. , Proud Virginia K.
Published: June 2005

Dormant Statoblasts germinate after prolonged treatment at 4° C, followed by incubation at 25° C. At 25° C, the activation period preceding germination is about 3 days; the polypide develops and buds once during the 3 days following germination. During the activation period, respiration increases 4‐fold and no significant changes in DNA, RNA or protein occur. Polysomes and ribosomes in the 8,000‐g supernatant increase. A dramatic 4‐fold increase in respiration occurs between 2 and 6 hours after germination, and little subsequent increase occurs. DNA and RNA increase steadily after germination, but protein remains constant. Actinomyc in D blocks post‐germination development but does not prevent germination. No germination inhibitor is released by statoblasts.
Response of the ovary in the catfish, Heteropneustes fossilis (Bloch), to various combinations of photoperiod and temperature
Authors: Vasal Sudhir , Sundararaj Bangalore I.
Published: June 2005

Responses of the ovary of the catfish, Heteropneustes fossilis, to various regimes of photoperiod and temperature, were studied during the different periods of the annual ovarian cycle. During the preparatory and postspawning periods moderate temperatures of 25°C and above, regardless of photoperiod, were more favorable for the formation of yolky (stage III) oocytes than cooler temperature (below 23°C). Even under conditions of continuous dark or light, ovarian development occurred as a function of warm temperatures.

Gravid ovaries were maintained beyond the spawning period only with a temperature of 30°C, photoperiod notwithstanding. Nevertheless, moderate or cool temperatures did not prevent the ovarian regression that occurred by the first week of October in the post‐spawning period. Regulation of ovarian activity at least in part by an endogenous circannual rhythm appears possible.
Mating‐type‐specific soluble factors (gamones) in cell interaction of conjugation in the ciliate Oxytricha bifaria
Authors: Esposito Fulvio , Ricci Nicola , Nobili Renzo
Published: June 2005

Sexual reproduction in Ciliates occurs through pair formation (conjugation) between cells of complementary mating types. In many species, after complementary cells are brought together, a waiting period ensues, which lasts up to the initial visible ciliary interaction leading to cell pairing. An exchange of information, mediated by soluble factors (gamones) takes place during the waiting period of Oxytricha bifaria. This hypotrich ciliate possesses a multiple mating type breeding system, and conjugation may thus occur between cells belonging to any two mating types. The excreted gamones being mating type specific, differ from each other. Any cell pretreated with any one of the complementary gamones starts pairing immediately after mixing. Thus cell interaction does not require heterologous cell to cell contact during the waiting period. A simple readily made apparatus to detect the exchange of information through soluble factors, is described.
The role of sodium and calcium lons in osmoregulation in Hydra littoralis
Authors: Koblick Daniel C. , Rufus Charles D.
Published: June 2005

The frequency of column contractions in Hydra littoralis (taken as a measure of the rate of water elimination) is maximal at about 5 × 10−4M Na+, and falls off markedly at higher and lower concentrations, even though total medium osmotic pressure is kept constant by replacement with K+.

Reduction in Ca++ concentration causes a reduction in the frequency of column contractions. This reduction is half‐maximal at about 4.8 × 10−4 M Ca++.

The significance of these findings in the light of the osmoregulatory mechanism in Hydra is discussed, and it is suggested that Na+ plays a regulatory role in the mechanism of extrusion of water and salts from the cells to the gastrovascular cavity.
Alterations in the developmental properties of stroma during the development of the urogenital ridge into ductus deferens and uterus in embryonic and neonatal mice
Authors: Cunha Gerald R.
Published: June 2005

The ability of mesenchyme from the urogenital ridge to participate in the development of male and female urogenital organs was studied by preparing homo‐and heterotypic recombinants of epithelium and stroma from ductus deferens and uterus of neonatal mice. The recombinants as well as intact 14‐day old embryonic urogenital ridges (UGR) were grown for two to eight weeks in adult male and female hosts. The development of ductus deferens and seminal vesicle from female UGR's grafted into male hosts and uterus from male UGR's grafted into female hosts demonstrates that the mesenchyme of embryonic UGR's is capable of participating in the development of either male or female urogenital structures. During normal development of the female urogenital tract, the bisexual morphogenetic potentiality of UGR mesenchyme persists postnatally as demonstrated by the ability of uterine stroma to support normal differentiation of epithelium of ductus deferens in male hosts. Conversely, during the normal development of the male urogenital tract, the morphogenetic potentiality of mesenchyme of the urogenital ridge is restricted as stroma from the ductus deferens appears incapable of participating in uterine morphogenesis in male or female hosts. These differences in the developmental properties of UGR stroma may be attributed to differences in hormonal conditions in male and female fetuses.
An ultrastructural analysis of chick embryonic skin development in vitro
Authors: Carinci P. , Simonelli L. , Bubola G. , Pettazzoni P.
Published: June 2005

Behaviour of 6‐day chick embryo thigh skin in vitro in two different nutrients was studied electron microscopically.

In explants supported with chicken serum containing medium epithelium keratinized faster than and in a similar way to that in ovo, except for the absence of corpuscola cribriformia in pericytes. It did not in explants supported with chick embryo extract containing medium, but underwent a noticeable ultrastructural evolution, mainly of granular reticulum and Golgi complexes.

In the two series of culturs mesenchyme presented the same ultrastructural characteristics, especially as far as collagen fibers were concerned.

The above data rule out the suggested regulatory role of collagen fibers in epidermal differentiation and support a possible epidermal two‐step differentiative process. They are discussed in relation to the general mechanisms implicated in skin evolution.
Adaptation of muscle pyruvate kinases to environmental temperatures and pressures
Authors: Low Philip S. , Somero George N.
Published: June 2005

Kinetic and structural properties of muscle pyruvate kinases from species adapted to different temperatures and hydrostatic pressures were examined. Most muscle pyruvate kinases can exist in two temperature‐dependent conformational states. For the low temperature conformers, activation free energies and enthalpies were proportional to the species' adaptation temperatures. The interspecific differences in activation parameters may be due to different amounts of weak bond formation/rupture during the rate‐limiting event(s) in catalysis. When comparisons of substrate binding ability at physiological temperature, is are made, a marked conservation in apparent Km values is observed among species. Structural rigidity, as estimated by heat inactivation temperature, is positively correlated with adaptation temperature. The apparent size of the conformational change which occurs during catalysis is also positively correlated with cell temperature, except for enzymes for deep‐sea species.
On the diversity of sperm histones in the vertebrates: II. A cytochemical study of the basic protein transitions during spermiogenesis in the cartilaginous fish Hydrolagus colliei
Authors: Bols N. C. , Kasinsky H. E.
Published: June 2005

Spermiogenesis in the ratfish (Hydrolagus colliei) is characterized by unusual changes in the basic proteins of the nucleus. Cytochemical analysis indicates that early spermatids in this cartilaginous fish contain the somatic type of histones. However, late spermatids contain the salmon type of sperm histone whereas spermatozoa display the mouse/grasshopper type designated by Bloch ('69). Such an unusual cytochemical shift from protamine in the spermatid to “stable protamine” in the sperm has not been documented heretofore.
The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. II. Juvenile hormone regulates sexual dimorphism in the distribution of antennal olfactory receptors
Authors: Schafer Rollie , Sanchez Thomas V.
Published: June 2005

Sexual dimorphism of antennal sense organs appears only at the adult stage during normal development of the cockroach, Periplaneta americana. Adult males acquire approximately twice as many olfactory sensilla as females at the terminal ecdysis. When terminal instar larvae are subjected to unilateral antennectomy, most ecdyse to supernumerary larvae rather than adults. Sexual dimorphism is not evident in the intact (unamputated) antenna during the extra larval stage, but appears at the following ecdysis which leads to the adult stage. Allatectomy of male and female larvae in the penultimate instar produces adultoids which show antennal sexual dimorphism. Whole‐body treatment of terminal instar larvae with exogenous juvenile hormone‐mimic (JH‐M) results in supernmerary larvae which lack antennal sexual dimorphism. When these superlarvae are removed from the influence of JH‐M, they ecdyse to adults with antennal sexual dimorphism. Topical application of JH‐M to male antennae early in the terminal larval instar results in the emergence of adults which lack the total male complement of antennal sensilla, but are otherwise normal‐appearing. These results indicate that an inhibitory action of juvenile hormone prevents the appearance of antennal sexual dimorphism during normal larval development.
Daily variations in the effects of disturbance on growth, fattening, and metamorphosis in the bullfrog (Rana catesbeiana) tadpole
Authors: Horseman Nelson D. , Meier Albert H. , Culley Dudley D.
Published: June 2005

Bullfrog tadpoles subjected to the daily disturbance of water replacement demonstrated differences in the rates of growth and metamorphosis and in fatbody weights which depended on the time of day when water replacement occurred. Early daily disturbances stimulated larval growth whereas midday disturbances stimulated metamorphosis. The time when the daily disturbances caused fattening changed during metamorphosis so that younger tadpoles fattened when disturbed early in the photoperiod and older tadpoles when disturbed at midday.
A contribution to the problem of the origin of the blastema cells in planarians: A karyological and ultrastructural investigation
Authors: Gremigni Vittorio , Puccinelli Ileana
Published: June 2005

The basic problem in Planarian regeneration, i.e., the origin of blastema cells, has been tackled by means of a karyological investigation carried out on a triplo‐hexaploid biotype of Dugesia lugubris. The main characteristic of this biotype is that male germ cells are karyologically distinguishable from female germ cells and from the somatic cells.

Sexually mature specimens were transected at a caudal level, posterior to the testes: from each transected specimen two regenerants were obtained, both of which formed a blastema. Thirty‐six hours after the transection most of the metaphase cells of the anterior regenerant blastema (a.r.b.) had 12 chromosomes. However, cells with 8 chromosomes as well as cells showing signs of chromosome elimination were also present. Three days after the transection only cells with 8 or 12 chromosomes could be detected in the a.r.b.

The ultrastructural examination of the 36‐hours‐old a.r.b. revealed that some blastema cells display features which can be interpreted as indicating a process of dedifferentiation, the others being virtually undifferentiated. In the posterior regenerant blastema (p.r.b.) of sexually mature specimens only cells with 12 chromosomes were present. The same applies to both the a.r.b. and p.r.b. of sexually immature specimens and to developing embryos.

These findings suggest that in the sexually mature planarians studied, the blastema is formed mainly by triploid cells. However, in those regenerants which still possess testes, immature male germ cells can also contribute to the blastema formation. The possible role played by these male germ cells in the reconstitution of the missing tissues in the biotype studied is also discussed.
Changes in the cell coat at the onset of gastrulation in Xenopus laevis embryos
Authors: Johnson Kurt E.
Published: June 2005

Four developmental stages of Xenopus laevis embryos were fixed in standard electron microscopic fixatives with 1% lanthanum nitrate added. This treatment reveals a lanthanum staining material (LSM) on the cell surface and in extracellular spaces. Morula and blastula stage cells have a small amount of LSM; in blastulae, 3±3 SD % of the cell surface is coated with LSM. In early gastrulae, 29±6 SD % of the cell periphery is covered with LSM. In late gastrulae, 82±13 SD % of the cell periphery is either coated with LSM or faces a space with LSM in it. There is also an appreciable accumulation of LSM within extracellular spaces during gastrulation.
Alterations in lipid composition of liver cell plasma membranes during development
Authors: Eberspacher Bruno E. , Organisciak Daniel T. , Massaro Edward J.
Published: June 2005

Liver plasma membranes of Swiss‐Webster CFW mice ranging in age from 5 to 165 days were isolated employing a two‐phase dextran/polyethylene glycol polymer system. Electron microscopy revealed low mitochondrial and microsomal contamination. Lipids were quantitatively extracted and subjected to two dimensional thin layer chromatography. Individual lipids were eluted and phosphorus was measured by the Malachite green method. Cholesterol was quantitated by the micro Lieberman‐Burchard method and sphingolipids were quantitated fluorometrically with fluorescamine.

During development, phosphatidylethanolamine levels decreased from 43.2% to 19.5% whereas phosphatidylcholine levels rose from 26.6% to 45.2%. The ratio of phospholipid/cholesterol remained essentially constant during development; but the sphingolipid/cholesterol and sphingolipid/phospholipid ratios increased from 0.75 to 1.79 and 0.11 to 0.34, respectively.
The phlorizin effect on the transport of sugars at the antiluminal face of teased flounder tubules
Authors: Kleinzeller Arnost , Dubyak George , Mullin James F. , McAvoy Elizabeth M.
Published: June 2005

The effect of phlorizin on the uptake of sugars by teased renal tubules of the flounder (Pseudopleuronectes americanus) and slices of rabbit kidney cortex was investigated:

Increasing concentrations (0.05–0.5 mM) of phlorizin inhibited the uptake of D‐glucose at the antiluminal face of the tubular cells by affecting primarily the cellular levels of glucose phosphates, whereas the levels of free glucose remained constant. This result suggests the possibility that the actual transport step is associated with sugar phosphorylation.

As opposed to the high affinity of phlorizin for the Na+‐dependent active transport system for methyl‐α‐D‐glucoside in flounder and rabbit kidney, the carrier shared by glucose, 2‐deoxyglucose and mannose at the antiluminal face of tubular cells displays a low affinity for the inhibitor.

It is suggested that glucose and its C2‐analogs enter the renal tubular cells at the antiluminal face by a phosphorylating pathway which has a low affinity for phlorizin, and mix readily with the metabolic pool. This transport pathway serves the nutritional requirements of the cells.
Regeneration of the retina in the adult newt,Triturus cristatus, following surgical division of the eye by a post‐limbal incision
Authors: Levine Robert
Published: June 2005

An autoradiographic and histological study of retinal regeneration following a post‐limbal ocular incision, inTriturus cristatus, is described. In these cases there is a major contribution to the regenerating retina from both the anterior complex (pars ciliaris retinae: ora serrata) and the retinal pigment epithelium. The tissue derived from the anterior complex can independently differentiate into retinal tissue if the anterior and posterior parts of the regenerate do not join. This contrasts with the situation following a limbal incision to the eye where the regenerative response of the anterior complex is inhibited.

The significance of labelling patterns in the regenerating retina, following administration of3H‐thymidine, is discussed.
Inhibition of epidermal cell migration by concanavalin A in skin wounds of the adult newt
Authors: Donaldson Donald J. , Mason James M.
Published: June 2005

Pigment cell migration was used as an indicator to study the effects of the plant lectin, concanavalin A (con A), on epidermal cell closure of skin wounds. Continuous immersion of wounded animals in 10–100 μg/ml of con A greatly slowed but did not stop epidermal cell migration. Thus, untreated animals closed wounds in 12 to 24 hours while some treated wounds were still open after three days. Removal from con A after 24 hours, allowed inhibited wounds to close faster than those left in con A. Brief (30‐minute) immersion of wounded animals in con A, either before or after migration had begun, suppressed closure for four to eight hours, demonstrating that the affinity for con A persists as epidermal cells migrate. When the left forelimb of bilaterally wounded animals was immersed in con A, it caused suppression of migration only on the immersed side, indicating a local rather than systemic site of action. Mixture with its competing sugar, alpha methyl D mannoside, abolished the effects of con A. The mechanism by which this lectin suppresses epidermal cell migration is unknown but clearly involves binding of the molecule to glycoprotein or glycolipid receptors on the cell surface.
Chronology of tooth development in the rainbow trout (Salmo gairdneri)
Authors: Berkovitz B. K. B.
Published: June 2005

A histological study was undertaken on the jaws of three rainbow trout (Salmo gairdneri) for which the previous dental record of each tooth position had been obtained by taking wax impressions of the jaws twice weekly. This has provided accurate data concerning the time sequence of events in the life cycle of the teeth. The periods of development leading to initial calcification, resorption and exfoliation of its predecessor, and ankylosis were rapid and each was calculated as taking no more than one week out of a life cycle, in the case of a mandibular tooth of a fish of body length 15 cm, of approximately 16 weeks. There was some evidence that resorption of a functioning tooth could commence internally as well as externally. Eruptive movements have to be accomplished rapidly and some contribution appears to be made by an uprighting of the tooth from its angled, developmental position.
Physiological adjustments to dilution of the external medium in the lip‐shark, Hemiscyllium plagiosum (bennett). III. Oxygen consumption and metabolic rates
Authors: Chan D. K. O. , Wong T. M.
Published: June 2005

During the initial period of adjustment of the lip‐shark, Hemiscyllium plagiosum, to a dilute medium there is an apparent decline in rate of oxygen consumption which is due mainly to the accumulation of water in the body. There is a rapid loss of lipid and glycogen from the liver.

After complete adaptation to the dilute medium, the oxygen consumption rate increases to the original level of the animal in sea water. A metabolic balance sheet based on the oxygen consumption, total nitrogen excretion and the assumption that muscle catabolism supplies the bulk of the energy, indicates that the lip‐shark has an elevated catabolic rate in the dilute medium. The calculated catabolic rate agrees well with the rate of loss in body weight in the unfed fish.

Blood glucose is well maintained while tissue‐lactate concentrations decline following adaptation to 46% sea water. Thus the availability of oxygen and metabolite are not limiting with respect to survival in diluted sea water.
Abnormal morphogenesis of feather structures and pattern in the chick embryo integument. II. Histological description
Authors: Brotman Harris F.
Published: June 2005

The development of skin and feathers in highly feathered scaleless mutants and normal Single Comb White Leghorn chick embryos was analyzed histologically. In addition, the growth of mutant feathers in chorioallantoic membrane culture is reported as a verification of several inferences made from observations of serially staged fixed specimens.

The most striking feature of scaleless high line feather development is the widespread appearance of condensed or nearly condensed dermis. The discrete arrangement of normal placodes with underlying condensed dermis is replaced in the mutant by a heterogeneously shaped group of extremely large islands of columnar (“placodized”) epithelium as long as 3,000 μ. The shape and extent of the condensed areas of dermis reflect the shape and extent of the overlying “placodized” epithelium. The polarity of the epidermis in normal feather germs, i.e., thicker epidermis on the posterior surface, is absent in mutant feather germs. This absence of epidermal polarity is reflected in the aberrant outgrowth of the mutant feather primordia.

In the mutant, the basal cell layer of the epidermis invades the dermal core of the aberrant feather germs and may form barb vane ridges or feather sheaths. This process has no counterpart in the development of normal down feathers.
Epidermal‐dermal tissue interactions between mutant foot skin and normal back skin: A comparison of the inductive capacities of scaleless low line and normal anterior foot dermis
Authors: Brotman Harris F.
Published: June 2005

The inductive capacities of 9‐ to 16‐day anterior foot dermis of scaleless low line and normal embryos were compared by recombining them with a common source of epidermis, i.e., 7‐day normal back epidermis. Tissue recombinants were cultured as grafts to the chorioallantoic membrane (CAM). Both normal and scaleless low line dermis of 12 to 13 days of incubation began to lose their ability to elicit feather production in 7‐day normal back epidermis. Normal foot dermis began to elicit scale production at 12 to 13 days, whereas scaleless low line anterior foot dermis maintained feather production at a low level.

It is inferred that without being associated with scale placode formation, scaleless low line anterior foot dermis does not acquire specific inductive capacities related to the production of an outer scale surface in the overlying epidermis. Feather placodes do not function as surrogates of scale placodes. The difference between normal and scaleless low line anterior foot dermis in terms of specific inductive capacities related to scale production is interpreted as a secondary effect of the action of the scaleless allele in interfering with scale placode formation in the scaleless low line anterior foot epidermis.
Low salt and high PH in the blood of amazon fishes
Authors: Mangum C. P. , Haswell M. S. , Johansen K.
Published: June 2005

All but one of 15 species of fishes and two crustaceans from the Amazon River system have reduced levels of inorganic ion activity in the blood, which results from the purity of Amazon waters. In many of the teleosts, low ion activity is accompained by high blood pH, due to the presence of high levels of HCO and ammonia. The activities of H+ and Cl− have the important respiratory consequence of raising the oxygen affinity of the hemoglobins in water‐breathing species in this chronically hypoxic environment.
Control of metamorphic events in a neotenous urodele Ambystoma mexicanum
Authors: Tompkins Robert , Townsend Janis K.
Published: June 2005

External metamorphosis in the normally neotenous urodele, Ambystoma mexicanum, can be induced by continuous immersion in thyroxine solutions of 5 × 10−8 M or more. The natural larval‐to‐adult hemoglobin change occurs in untreated animals at 100–150 days of age, unaccompanied by external metamorphosis. The hemoglobin change is inducible prematurely by continuous immersion of larvae in a thyroxine solution of at least 3 × 10−8 M‐a concentration insufficient to induce external metamorphosis.
Morphology of mouse egg cylinder development in vitro: A light and electron microscopic study
Authors: Wiley Lynn M. , Pedersen Roger A.
Published: June 2005

Phase contrast, light, and electron microscopy showed that mouse egg cylinder development from the blastocyst stage in vitro closely resembled the egg cylinder stages of the fourth to seventh days of gestation in vivo. Primary endoderm and ectoderm formed on day 2 of culture, and on day 3 visceral and parietal endoderm could be distinguinshed. Mesoderm formed on days 6.5‐7 by delaminating from a thickened region of embryonic ectoderm. Extraembryonic ectoderm developed as single layer of cuboidal epithelial cells that appeared to originate from polar trophoblast cells. By day 8 of culture egg cylinders had an ectoplacental cavity, an exocoelom, a proamnionic cavity, a chorion, and an allantois and resembled egg cylinders in vivo after seven days' gestation. However, cultured blastocysts took longer to develop to these egg cylinder stages than embryos in vivo (8 days in vitro vs. 4 days in vivo) and were shorter (600 μm in vitro vs. 700 μm in vivo). The development of mural trophoblast, parietal endoderm, Reichert's membrane, and ectoplacental cone also differed from that of their counterparts in vivo. Nevertheless, because the egg cylinder itself, which produces the embryo proper, develops similarly in vitro as in vivo, we suggest that cultured mouse blastocysts provide an excellent model for studies on early postimplantation embryogenesis.
Bioelectricity and regeneration. I. Initiation of frog limb regeneration by minute currents
Authors: Borgens R. B. , Vanable J. W. , Jaffe L. F.
Published: June 2005

We have applied 0.2 μamps of current to the forelimb stump of Rana adults for several weeks. The stimulator was designed to avoid introduction of any physiologically active electrode products into the tissue. Current was applied to the dorsal postaxial region of the stump. Cathodal (i.e., distally negative) current initiated partial regeneration; anodal (i.e., distally positive) current initiated extensive destruction of the limb; while implantation of sham stimulators (delivering no current) yielded limbs showing just a healing response. Regeneration was indicated by organized extension of the severed radio‐ulna, newly formed muscle, ligament, and isolated cartilage rods that were partially segmented. Moreover, extraordinarily large amounts of nerve developed in the regenerated tissue. We conclude that the cathodally initiated regeneration was mediated by small electrical fields within the stump and not by electrode products. However, an electrode product (Ag+ ion) cannot be completely excluded as a possible mediator of anodal destruction.
Budding inHydra attenuata:Bud stages and fate map
Authors: Otto Joann J. , Campbell Richard D.
Published: June 2005

Ten bud stages are defined and their profiles illustrated. A fate map of the developing bud ofHydra attenuatawas made using vital intracellular marking. Marks made at increasing distances from the young bud tip end up in increasingly more proximal regions of the bud. There is no major difference between the recruitment patterns of cells from above, below and lateral to the bud tip. The angular positions of cells on the parent is directly correlated with their final angular positions on the bud axis. Therefore, tissue is recruited in concentric rings around the young bud tip and is distorted directly outward into the bud column. At the youngest bud stages, the fate map of the bud extends about 180° around the parent.

Tissue recruitment from the parent ends at the time that tentacle rudiments appear on the bud. Thus, tissue recruitment and hydranth morphogenesis are separate processes.
Liver regeneration in normal and alloxan‐induced diabetic rats
Authors: Barra Rosemary , Hall James C.
Published: June 2005

The effects of alloxan‐induced diabetes on liver regeneration were investigated. Normal and diabetic rats were sacrificed at eight time periods between 16 hours and 4 weeks following two‐thirds partial hepatectomy or sham operation. The results indicate that alloxan‐induced diabetes delays but does not prevent liver regeneration following partial hepatectomy. This delay is indicated by a depressed synthesis of RNA, DNA and protein during the first post‐operative day and a lack of mitotic figures in the 24‐hour sample. In addition, the synthesis of these three cellular constituents did not return to control levels as rapidly in the diabetics. Compared with the sham operated animals, the concentrations of total serum protein remained depressed longer in the diabetic hepatectomized animals. The data indicate that the metabolic alterations associated with alloxan diabetes delay the onset of the regenerative process and prolong the recovery period.
Inhibition of maturation and metabolism in rat oocytes by cyclic AMP
Authors: Magnusson Claes , Hillensjö Torbjörn
Published: June 2005

It is known that dibutyryl cyclic AMP (dbcAMP) and theophylline inhibit the spontaneous maturation of isolated mouse oocytes. The present study demonstrates that dbcAMP (0.01 – 1.0 mM) as well as cyclic AMP (cAMP, 10 mM) and a phosphodiesterase inhibitor (IBMX, 0.01 – 1.0 mM) prevent spontaneous maturation of isolated rat oocytes. As reported earlier an increase in oxygen consumption by the oocyte was found following maturation. When the oocytes were cultured in the presence of dbcAMP or cAMP no change in respiration occurred during culture.

These results argue against the theory that cAMP acts as a direct mediator of the action of luteinizing hormone (LH) on oocyte maturation. Furthermore they suggest that changes in oocyte energy metabolism are closely related to the maturation process.
Zooxanthellae‐produced O2 promotes sea anemone expansion and eliminates oxygen debt under environmental hypoxia
Authors: Malcolm J. Malcolm , Brown Warren I.
Published: June 2005

During exposure to hypoxic conditions in darkness, Anthopleura elegantissima remains contracted and incurs a physiological oxygen debt. Both of these phenomena are eliminated by maintaining anemones in the light, but not if photosynthesis by their endosymbiotic zooxanthellae is chemically inhibited, suggesting that the intracellular production of O2 stimulates expansion and enables aerobic metabolism to continue.
The ultrastructure and the hormonal control of product synthesis in the hedonic glands of the red‐spotted newt Notopthalmus viridescens
Authors: Pool Thomas B. , Dent James Norman
Published: June 2005

The ultrastructure and the hormonal regulation of hedonic glands in male and in female red‐spotted newts have been studied throughout the year and under various experimental conditions. Hedonic glands are simple, alveolar, merocrine glands that contain a single layer of secretory epithelial cells surrounded by a discontinuous layer of myoepithelial cells. Although hedonic glands from both sexes are alike in form, females have only about a third as many as do males. While newts are in breeding conformation during the fall, winter, and spring, large quantities of a glycoproteinaceous product are sequestered within the lumina of their hedonic glands. During those seasons the secretory cells are cuboidal and contain abundant rough endoplasmic reticulum with dilated cisternae and active Golgi complexes. Secretory granules are numerous in the apical cytoplasm and appear to be attached to microfilaments and microtubules. During the summer months, secretory cells are quiescent and assume a columnar configuration, reducing the lumen to negligible proportions. Rough endoplasmic reticulum is sparse, residual secretory granules contain small vacuities, and lipid droplets and glycogen aggregates occur. Hedonic glands of newts in breeding conformation regress to the summer state within three to four weeks under laboratory conditions. In laboratory‐conditioned, gonadectomized male newts hedonic glands remain unchanged after treatment with saline, prolactin, or testosterone but are transformed to the breeding state by treatment with prolactin and testosterone in combination. Hedonic glands from ovariectomized females respond similarly to prolactin in combination with testosterone, but fail to respond to prolactin with estradiol.