bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen‐binding properties of hemoglobins from estivating and active African lungfish
Authors: Weber Roy E. , Johansen Kjell , Lykkeboe Gunnar , Maloiy Geoffrey M. O.
Published: June 2005

The oxygen‐binding characteristics and the multiplicity of the stripped hemoglobin from active lungfish Protopterus amphibius, are the same as in specimens that have been estivating for about 30 months, showing that alteration in the hemoglobin molecules is not involved in the earlier reported increase in oxygen affinity of whole blood during estivation (Johansen et al., '76). At pH 7.0 and 26°C the hemolysates show a high oxygen affinity (P50 = 3.1 Torr), a Bohr factor (Δ log P50/Δ pH) of −0.33, and a cooperativity coefficient (n) of 1.7. Between 15 and 26°C, the apparent heat of oxygenation (ΔH) is −8.6 Kcal·mole−1 at pH 7.0, corre‐sponding with data for other fish. A low sensitivity of oxygen affinity to urea appears to be adaptive to the high urea concentrations in estivating lungfish. The salt sensitivity is, however, similar to human hemoglobin.

The hemoglobin consists of two major (electrophoretically anodal) components, which differ slightly in oxygen affinity but are both sensitive to pH and nucleoside triphosphates (NTP). Guanosine triphosphate (GTP), the major erythrocytic organic phosphate, however, depresses the oxygen affinity of the composite and separated hemoglobins more effectively than ATP suggesting that GTP is the primary modulator of oxygen affinity.

Comparative measurements reveal only one major hemoglobin component in P. annectens which has a markedly lower oxygen affinity and phosphate sensitivity than P. amphibius hemoglobins and thus seems less pliable to phosphate‐mediated variation in oxygen affinity.

The data are discussed in relation to the hemoglobin systems of other fish.
Thymus‐dependent lymphoid regions in the spleen of the lizard, Calotes versicolor
Authors: Pitchappan R. M. , Muthukkaruppan V. R.
Published: June 2005

This paper describes the distribution of thymus‐derived lymphocytes in the spleen of the lizard, Calotes versicolor. Our studies reveal the existence of red and white pulp in the spleen. The red pulp consists of collagenous fibrous septae containing lymphocytes, erythrocytes and sinuses. The white pulp is an area enclosed by fibrous septae, containing lymphocytes, reticular cells and arterioles. The region around the arteriole in the white pulp was depleted of lymphocytes either one month after adult thymectomy or after anti‐thymocyte serum treatment. The repopulation of this region was observed in sham‐thymectomized controls, but not in thymectomized lizards. Therefore, this peri‐arteriolar region may be designated as a thymus‐dependent area, as described previously in higher vertebrates. The significance of these findings is discussed in relation to the phylogeny of the immune system.
The nature and development of sex attractant specificity in cockroaches of the genus periplaneta. IV. Electrophysiological study of attractant specificity and its determination by juvenile hormone
Authors: Schafer Rollie
Published: June 2005

The antennae of male Periplaneta americana acquire a large number of olfactory receptors at the adult stage. Electrophysiological methods (single unit and electroantennogram recording) show that a portion of the receptors added at the adult ecdysis are sex attractant receptors. Sex attractant receptors are not present in large numbers on larval and adult female antennae. The differentiation of pheromone receptors is inhibited during normal larval development by juvenile hormone. Topical application of juvenile hormone‐mimic to male antennae during the terminal larval instar inhibits their development. Comparative electrophysiological studies indicate a high degree of cross‐reactivity of the P. americana sex attractant among four other species within the genus Periplaneta.
Ureotelism in the slug, Limax flavus linné
Authors: Horne Francis R.
Published: June 2005

The slug, Limax flavus, excretes both urea and purines.

Urea and purines account for up to 59 and 41% of the excretory nitrogen, respectively.

Of the purines excreted uric acid predominates (64%) with quanine (22%) and xanthine (14%) usually being voided in lesser amounts. Neither adenine or hypoxanthine was detected.

Urea was excreted in urine while the purines were deposited irregularly, as semi‐solid, yellowish nubs.
Neurotrophic stimulation of DNA synthesis in the regenerating forelimb of the newt, Triturus
Authors: Jabaily Joseph A. , Singer Marcus
Published: June 2005

The effect of infusions of soluble newt brain extracts on deoxyribonucleic acid (DNA) synthesis in the denervated, regenerating newt blastema has been studied. When moderate early to early regenerates are denervated for 48 hours, DNA synthesis normally drops to about 40% of that found in contralateral, innervated blastemas. Infusion of brain extract halfway through the denervation period (at 24 hours) approximately doubles the rate of DNA synthesis in denervated regenerates.
The effect of 5‐bromodeoxyuridine on the postnatal development of the rat testis
Authors: Barasch Jonathan M. , Bressler Robert S.
Published: June 2005

The effects of 5‐bromodeoxyuridine (BrdU) on postnatal testicular development were studied in rats treated on the second, third and fourth days of life. Testes were removed for study at 5, 15 and 35 days of age. Body weights and diameters of seminiferous cords and tubules were significantly less in the treated than control animals. At 15 days of age fewer pachytene spermatocytes were present in treated animals. At 35 days of age the testes of treated animals contained fewer canalized cords. Spermatids exhibited an altered distribution of chromatin material, contained less agranular endoplasmic reticulum and fewer mitochondria, and had not yet developed tails. Sertoli cells and Leydig cells of treated animals contained less agranular endoplasmic reticulum and more lipid droplets than the normal.
Temporal coordination and spatial autonomy in regulation of ciliary pattern in double forms of a hypotrich ciliate Paraurostyla weissei
Authors: Jerka‐Dziadosz Maria
Published: June 2005

Regulation of cortical pattern was analyzed in homopolar back‐to‐back doublets of Paraurostyla weissei. After surgical removal of the anterior quarter of one component, both components form primordia of the ciliature, each one positioning the primordia according to its own boundaries. Both regenerated components were measured several hours after the operation, and the number of cortical elements was counted in each component. On the average, the operated component is smaller by about 17% and possesses about 25% fewer AZM membranelles and about 14% fewer left marginal cirri than the unoperated component. The analysis shows that in spite of the endoplasmic and membrane continuity and the morphogenetic signals passing from one component to the other, the two halves of a doublet show remarkable autonomy both in positioning of the primordia and in regulation of the number of cortical elements, which remain proportionate to the size of each component of the double form.
Changes in the levels of chloride cells and (Na+ + K+)‐dependent ATPase in the gills of yellow and silver eels adapting to seawater
Authors: Thomson A. J. , Sargent J. R.
Published: June 2005

Changes were measured in the numbers of chloride cells and the levels of (Na+ + K+)‐dependent ATPase in the gills of immature, yellow eels and mature, silver eels during adaptation from freshwater to seawater. The percentage of chloride cells in yellow eels more than doubled after six days in seawater; at this time the specific activity and concentration of (Na+ + K+)‐dependent ATPase in gills start to increase in parallel to reach maxima after two weeks that are 2.5 times the starting values. It is concluded that adaptation of yellow eels to seawater involves an increase in the numbers of chloride cells in gills as well as an increased amount of (Na+ + K+)‐dependent ATPase per chloride cell. Mature silver eels in freshwater had essentially the same numbers of chloride cells and the same specific activity of the enzyme in the gills as yellow eels fully adapted to seawater. Transferring silver eels to seawater did not alter the percentage of chloride cells in gills although the level of (Na+ + K+)‐dependent ATPase and its specific activity increased slightly. Thus, although the silver eel is better prepared for life in seawater than the yellow eel, it still has to attain an increased level of (Na+ + K+)‐dependent ATPase in its chloride cells to be fully adapted to seawater.
Physiological adjustments to dilution of the external medium in the lip‐shark Hemiscyllium plagiosum (bennett). I. Size of body compartments and osmolyte composition
Authors: Chan D. K. O. , Wong T. M.
Published: June 2005

The lip‐shark Hemiscyllium plagiosum can survive gradual dilution of the external medium to a salinity of about 12% sea water.

Throughout the range in salinity from undiluted sea water to 25% sea water a plasma osmolarity greater than that of the medium is maintained. In undiluted sea water the concentrations of the plasma electrolytes Na+, K+, Ca++, Mg++ and Cl− are much lower than those of the medium. The high plasma osmolarity is due largely to urea.

In dilute media, lip‐sharks gain considerable amounts of water. There is a marked expansion of the blood volume and intramuscular fluid space. Although the massive influx of water causes a significant decline in electrolyte concentrations in plasma and intramuscular space, the total electrolyte content is maintained. Urea content, on the other hand, declines significantly following adaptation to dilute media.

Near the lowest salinity in which survival can occur there is a rapid decline in concentration of Ca++ in the plasma and intramuscular fluid. The concentration gradient of K+ and Cl− between the extracellular and intracellular compartments of the parietal muscle also declines so that the calculated diffusion potential across the myolemma for both ions decreases significantly. These changes may be related to the inactivation of muscle and respiratory failure prior to death.
Progesterone‐induced DNA polymerase activity in full‐grown oocytes of xenopus laevis
Authors: Grippo P. , Locorotondo G. , Taddei C.
Published: June 2005

DNA polymerase activity increases in full‐grown oocytes of Xenopus laevis during in vitro progesterone‐induced maturation. This increase in inhibited by cycloheximide. The presence of the oocyte's nucleus (germinal vesicle) seems essential for the induction of this increase: in previously enucleated oocytes, the level of DNA polymerase activity does not change during progesterone treatment.

Furthermore, a new form of DNA polymerase is detectable by DEAE chromatography in in vitro matured oocytes.
Relationship between net 45calcium influx across a perfused isolated eel gill and the development of post‐stanniectomy hypercalcemia
Authors: So Ying‐Peng , Fenwick James C.
Published: June 2005

The net 45calcium influx was measured in perfused isolated individual hemibranchs taken from Anguilla rostrata L. at various intervals following the surgical removal of the Corpuscles of Stannius. Total plasma calcium concentrations were record at the same time.

A relationship between the development of post‐stanniectomy hypercalcemia and the net rate of 45calcium uptake in the isolated gills is suggested. The net influx of 45calcium increased rapidly during the first week, peaked at two weeks and dropped back to control levels at three weeks. Plasma calcium levels followed the same trend over the first two weeks but continued to rise through the third week before dropping slightly during the fourth week.

We conclude that the corpuscles of Stannius play some role in controlling the branchial uptake of calcium and that the gills are of primary importance in the appearance of post‐stanniectomy hypercalcemia.
Ultrastructural analysis of gene interaction and melanosome differentiation in the retinal pigment cells of the albino goldfish
Authors: Kajishima Takao , Takeuchi Ikuo K.
Published: June 2005

The genotype of albino goldfish is represented by pp,cc, and the non‐albino fish is PP,CC. The P gene begins to control the melanosome formation of retinal pigment cells at St‐21; and the C, which is epistatic to P and p, governs melanosome formation in the dermal melanophores and in retinal pigment cells after St‐22. Then in the pp,CC fish, between St‐21 and St‐22, melanosomes of the pigmented retina are albino in type, but after St‐22 they become non‐albino in type. From ultrastructural observations on the melanosomes of these late‐melanizing fish, it is apparent that the incompletely melanized albino pigment granules can differentiate into normal melansomes under the control of the C gene. The processes of melanosome maturation in the late‐melanizing goldfish are evident from these observations.
Studies of the developmental potential of 4‐ and 8‐cell stage mouse blastomeres
Authors: Kelly Susan J.
Published: June 2005

The object of this study was to assess the full developmental potential of all the blastomeres in 4‐cell and 8‐cell stage mouse embryos. Isolated blastomeres at these stages have limited developmental powers, and in order to follow their development into the postimplantation period a method of combining each blastomere into a chimaeric composite was devised. Preliminary experiments indicated the most favourable genetic combinations and blastomere arrangements. For the 4‐cell stage embryos each individual donor blastomere was combined with genetically distinct blastomeres at the same stage to make a “Quarted” of composite embryos. The occurrence of the donor cell characters in these composites when they were recovered at the tenth day of pregnancy and at term, indicates that each 4‐cell stage blastomere is totipotent and may contribute extensively to a mouse and also to the yolk sac and trophoblast. Eight‐cell stage blastomeres were obtained in pairs, each pair being derived from a particular 4‐cell stage blastomere. The development of the pairs were followed in chimaeric composites. Each blastomere of a pair was found to have the same range of developmental potential. This indicates a lack of segregation of morphogenetic factors and implies totipotency of the 8‐cell stage blastomeres. The relevance of these results to the current theories of blastocyst differentiation is discussed.
Exceptional tolerance to low pH of some tropical blackwater fish
Authors: Dunson William A. , Swarts Fred , Silvestri Mark
Published: June 2005

Cardinal, neon, and emperor tetras (Cheirodon axelrodi, Hyphessobrycon innesi, Nematobrycon palmeri), small South American characin fish often found in acidic blackwater rivers, have an unusual tolerance to sulfuric acid solutions of low pH. Most cardinal tetras withstand immediate transfer to water at pH 3.5 for an indefinite period. With gradual adjustment to further stepwise lowering of the pH, one individual survived at a pH of 3.1 for five weeks. This is by far the most acidic solution known to be tolerated for extended periods by any fish. The lower incipient lethal level (for 50% survival) is estimated to be about 3.35 for neon and cardinal tetras. On the other hand, common guppies (Poecilia reticulata), a species generally considered to be highly resistant to environmental change, all died after 11 days at pH 4.75. Both guppies and tetras lose large amounts of body sodium on exposure to lethal pH's.
Nucleic acid synthesis in preimplantation rabbit embryos. III. A “dark period” immediately following fertilization, and the early predominance low molecular weight RNA synthesis
Authors: Manes Cole
Published: June 2005

This report stems from efforts to characterize the products of trancription during the initial stages of cleavage in the rabbit embryo, since previous studies have suggested that RNA synthesis is required during this period for the continuation of normal development. Early cleaving embryos were exposed to radiolabeled precursors of nucleic acids in vitro and RNA extracted and analyzed by polyacrylamide gel electrophoresis and BD‐cellulose chromatography. No unequivocal evidence of RNA synthesis could be obtained during the first three cleavage divisions; all apparent “embryonic” RNA synthesis could be ascribed to contaminating follicle cells. After the fourth cleavage, however, there is readily detectable incorporation of radioisotope into RNA by embryos which have been denuded of follicle cells. Two‐thirds of the cytoplasmic RNA labeled during a 4‐hour period is 25–30 × 103 daltons in size, and some of this low molecular weight RNA can be aminoacylated and shown to be transfer RNA. A low level of ribosomal RNA synthesis is detectable at this stage. The contribution, if any, of the rabbit embryonic genome to development prior to the 16‐cell stage remains to be defined.
An analysis of water‐content regulation in osmoconforming limpets (Mollusca: Patellacea)
Authors: Tarr Kathleen J.
Published: June 2005

The capacity to regulate body volume is important in the ability of soft‐bodied osmoconforming marine animals to withstand osmotic stress. In the present study two intertidal limpets, Collisella digitalis and Notoacmea scutum, which differ in their tolerance of osmotic stress, are compared in their ability to regulate water content. Two direct measurements and two mathematical approaches developed by Oglesby ('75) and Machin ('75), respectively, have been used. Both species are osmoconformers over the range 500–1,500 mOs/1 but showed a slight tendency to hyporegulate Cl− and Na+ in the hemolymph. In weight and tissue hydration changes following a change in osmotic pressure of the medium, C. digitalis did not vary as widely as did N. scutum and so appears to have better control of body volume. This correlates well with the previous finding that C. digitalis tolerates a wider range of salinity than does N. scutum.
The phylogenetic distribution of red cell 2,3 diphosphoglycerate and its interaction with mammalian hemoglobins
Authors: Scott A. F. , Bunn H. F. , Brush A. H.
Published: June 2005

In order to better understand the extent to which 2,3 diphosphoglycerate (DPG) contributes to red cell function in the mammals, we assayed DPG levels in blood from a taxonomically diverse set of 71 species representing 14 orders. In addition, for 66 species and 4 hemoglobin phenotypes of the sheep, the effect of DPG on oxygen affinity was measured by determining P50 values for hemoglobin in the absence of DPG and at 0.2 mM and 1.0 mM concentrations. Most mammals had high levels of red cell DPG and phosphate‐free hemoglobins with a relatively high oxygen affinity. In contrast, two taxonomically unrelated groups had both very low intra‐erythrocytic DPG concentrations as well as hemoglobins of native low oxygen affinity that interacted weakly with DPG. This latter group includes the Feloidea (order Carnivora) and the Bovoidea (order Artiodactyla). The relationship between DPG concentration, hemoglobin oxygen affinity and the interaction of DPG with hemoglobin is treated quantitatively to provide a model of mammalian red cell function. This derived expression is compared with descriptive allometric equations for whole blood P50 and is shown to provide statistically reasonable predictions.
The estrous cycle in golden hamsters: A circadian pacemaker times preovulatory gonadotropin release
Authors: Stetson Milton H. , Gibson Jeffrey T.
Published: June 2005

In a population of cycling female hamsters entrained to an LD 6:18 light cycle (lights 1000–1600 hours), preovulatory release of luteinizing hormone and follicle‐stimulating hormone occurred in some animals at 1300–1400 hours and in others at 1900 hours. In every case peak release was phase‐locked (2–3‐hour positive phase angle) to the circadian rhythm of locomotor activity. The pattern of entrainment of gonadotropin release on LD 6:18 is fully explicable in terms of the hamster's phase response curve to light. We conclude that periodic gonadotropin release in cycling females is timed by a circadian oscillator (biological clock) that is probably the same oscillator driving the circadian rhythm of locomotor activity.
Two types of hemocytes in localization of clottable protein in Japanese horseshoe crab, Tachypleus tridentatus
Authors: Shishikura F. , Chiba J. , Sekiguchi K.
Published: June 2005

Localization of clottable protein (CP) in hemocytes of the Japanese horseshoe crab, Tachypleus tridentatus, was investigated by a fluorescent antibody technique. The cytoplasmic granules in the minority of hemocytes (15%) were stained strongly and uniformly while those in the majority of hemocytes (85%) were not. In contrast, the cytoplasmic matrix of the majority was stained with various degrees of intensity and that of the minority was not. The two types of hemocytes which showed different intracellular localization of CP might be in different maturational stages or might play different roles in blood coagulation.
Incorrect connections made by a regenerating cockroach motoneuron
Authors: Whitington Paul M.
Published: June 2005

An identified cockroach motoneuron, mesothoracic cell 30, the fast excitatory motoneuron to the coxal depressor muscles, has been found to make connections with inappropriate muscles after regenerating to a leg from which its correct muscles had been excised. Thus the specificity of innervation shown by motoneurons regenerating to a normal, intact leg cannot be due solely to a one‐to‐one matching of motoneurons with muscles.
Synthesis of RNA by male pronuclei of fertilized sea urchin eggs
Authors: Longo Frank J. , Kunkle Mel
Published: June 2005

Experiments have been conducted in an effort to determine when the paternally derived genome of sea urchin embryos becomes active in RNA synthesis. Participation of the paternal genome in RNA transcription as early as fertilization has been indicated by the following: (1) polyspermic zygotes consistently demonstrate greater levels of incorporation of labelled precursor (3H‐uridine) into RNA when compared to monospermic eggs. (2) Monospermic and polyspermic eggs treated with actinomycin D show the same levels of incorporation of label into RNA. (3) Analysis of autoradiographs demonstrates the incorporation of 3H‐uridine into male and female pronuclei.
Heart rate response to light in the embryo of the Japanese quail (Coturnix coturnix)
Authors: Ockleford Elizabeth M. , Vince Margaret A.
Published: June 2005

The effects of exposure to light were investigated during and shortly after the period of light stimulation. A particular objective was to evaluate any responses to the type of illumination conditions generally used for observation of avian embryos. Twenty 16‐day Japanese quail embryos were illuminated for 15 minutes each during a total recording period of 55 minutes. Heart rate, respiration rate and an approximate measure of activity were recorded. Mean heart rate was found to be higher during stimulation than before and did not return to the prestimulation level during the recording period after stimulation ceased. The lack of an immediate heart rate response to the onset of stimulation separates the effects of light from those of touch, rotation, odours, tastes and maternal calls. The possibility that light may act to stimulate accelerated development is discussed.
Segregation during cleavage of a factor determining endodermal alkaline phosphatase development in ascidian embryos
Authors: Whittaker J. R.
Published: June 2005

Localized alkaline phosphatase activity (EC 3.1.3.1) develops progressively in endodermal tissues of the presumptive digestive system in Ciona intestinalis embryos. It was first detected histochemically at late gastrulation, and a puromycin sensitivity period coincident with this time suggests that new alkaline phosphatase is synthesized. Embryos in which cell division was blocked with cytochalasin B at early cleavage stages up to the 64‐cell stage, eventually differentiated strong alkaline phosphatase activity in certain cells at each cleavage‐arrested stage. The maximum cell numbers and their positions were identical to those of the previously known endodermal cell lineage. Actinomycin D did not prevent development of endodermal alkaline phosphatase when administered from fertilization onwards, nor did other inhibitors of RNA synthesis (chromomycin A3, cordycepin, and daunomycin). There is probably a preformed maternal mRNA for endodermal alkaline phosphatase present in the unfertilized Ciona egg. Either this RNA itself, or some related translation factor, is localized in the egg cytoplasm and segregated during early cleavages into the endodermal cell lineage of the embryo.
Effects of neurotransmitters upon the discharge of secretory product from the cutaneous glands of the red‐spotted newt
Authors: Hoffman Charles W. , Dent James Norman
Published: June 2005

The effects of sympathetic and parasympathetic agonists and antagonists on discharge of secretory product by the granular and mucous glands were examined in the red‐spotted newt, Notopthalmus viridescens viridescens. Observations were made also on the South African clawed toad, Xenopus laevis, the grass frog, Rana pipiens, and the crested newt, Triturus cristatus.

In contrast to the granular glands of the South African clawed toad and the grass frog, which were stimulated by α‐adrenergic agents, those of the red‐spotted newt discharge in response to acetylcholine, either in vitro when added to the Holtfreter's solution in which explants were incubated, or in vivo when injected subcutaneously. Granular glands of the crested newt were also discharged in response to subcutaneous injection of acetylcholine. Stimulation of the granular glands by acetylcholine was blocked by atopine but not by tubocurarie, indicating that the cholinergic receptors are muscarinic rather than nicotinic. The mucous glands of the red‐spotted newt, on the other hand, did not discharge in response to either acetylcholine or to adrenergic agents.
Evidence for multiple cell surface chicken fetal‐leukemic antigens (CFA) in the developing chick and other avian species
Authors: Dietert R. R. , Sanders B. G.
Published: June 2005

Chicken fetal antigen (CFA), a membrane antigen present on fetal chicken red blood cells is lost with chicken development, and reappears on the red blood cells of leukemic chickens. Seven avian species were found to possess CFA. A species hierarchy comparing the quantitative expression of CFA has been established. The levels of CFA expression with development are compared in the chicken and Japanese quail.

Specific adsorptions of R‐anti‐CFA with avian red blood cells revealed the existence of multiple CFAs. Four groups of antigenic determinants (CFA a,b,c,d) have been characterized and defined by their expression among avian species. Multiple CFA determinants are discussed with regard to possible membrane alterations and gene function.
Regulation of cell proliferation in tadpole limb epidermis by thyroxine
Authors: Wright Mary L.
Published: June 2005

The mechanism of thyroxine control of cell proliferation was investigated by studying cell cycle kinetics in limb epidermis of control and thyroxine‐treated Rana pipiens tadpoles using repeated labeling and construction of percent labeled mitoses curves. Changes in labeling index may be attributed primarily to alteration in either the relative length of S in the cell cycle (S/T), or the growth fraction of the cell population. In limb bud epidermis of Stage III tadpoles growth fraction, like labeling index, increased in basal cells but did not change in outer layer after 24 hours of 3, 30 or 300 μg/l thyroxine treatment. Changes in cell cycle parameters, however, were small and similar in both outer and basal layers, and there was no appreciable change in S/T. At Stages IX to XI, changes in labeling index and growth fraction were also parallel. Both parameters increased in intermediate and basal cells but decreased in outer layer after 30 or 300 μg/l thyroxine treatment for 48 hours. In addition, there was a decrease in S/T, due to a lengthening of G1 + ½M and a shortening of S. The cell cycle changes at Stages IX to XI were similar in all layers as at Stage III, regardless of whether labeling index increased or decreased. The results indicate that the specific changes in labeling index observed during thyroxine‐induced growth and differentiation of limb epidermis are linked closely to regulation of size of the proliferative pool, although alterations in cell cycle parameters are of some significance in older tadpoles.
The presence of sperm‐specific surface isoantigens on the egg following fertilization
Authors: O'Rand Michael G.
Published: June 2005

Sperm surface isoantigens can be detected on the surface of fertilized eggs by using cytotoxic (complement dependent) sperm‐specific isoantisera. These isoantigens cannot be detected on unfertilized eggs. This may indicate their transfer from sperm to egg during fertilization.
Pigment cell differentiation in embryonic mouse skin and isolated epidermis: An in vitro study
Authors: Mayer Thomas C. , Oddis Leroy
Published: June 2005

Pigment cell differentiation was studied in cell cultures derived from 14‐day embryonic mouse skin, and in cultures of dermal or epidermal skin cells. Cell cultures from dissociated whole skin produced melanocytes in very small numbers, and they were always present in association with groups of epithelial‐like cells. Cell cultures from dissociated dermis produced no melanocytes during the three week culture period.

Epidermal cultures established from mechanically produced small aggregates of cells first formed melanocytes after 30 hours in culture, and large numbers of melanocytes were present after two days. Epidermal cells, in contrast to other cells, did not survive in culture beyond 11 days, and consequently surviving populations of pure melanocytes were left remaining on the plate surface. Epidermal cultures prepared from albino embryos resulted in amelanotic melanocyte populations remaining following the epidermal cell death. Epidermal cell cultures from white‐spotting mutant embryos (W/W and S1/S1) left no cells on the plate recognizable as being of the pigment cell lineage. The enhancement of melanoblast differentiation by epidermal cells, and the relationship between melanocytes and epidermal cells revealed in cell culture may be useful in the analysis of early stages of melanoblast differentiation, and in the study of mechanisms of gene action involved in this process.
Photokinesis and behavioral thermoregulation in adult sea lampreys (Petromyzon marinus)
Authors: McCauley Robert W. , Reynolds William W. , Huggins Norman H.
Published: June 2005

Photokinetic responses of adult sea lampreys were used to facilitate study of their thermoregulatory behavior in a laboratory thermal gradient. Lampreys swam about actively when room lights were switched on, but attached themselves to the side walls at temperature‐dependent sites in the gradient when lights were turned off. Attachment sites were significantly correlated with temperature (correlation coefficient = 0.73, p < 0.01). Acete mean preferred temperature of five lampreys, previously acclimated at 10°C, was 14.3 ± 3.0 (S.D.) °C. This is the first experimental demonstration of behavioral thermoregulation in this ancient class of jawless vertebrates (Agnatha).
Are sugar residues involved in the specific cell recognition of mating in Paramecium?
Authors: Kitamura Akio , Hiwatashi Koichi
Published: June 2005

To characterize the chemical nature of the substances responsible for the agglutinative mating reaction in Paramecium caudatum, the effects of a variety of reagents on the mating activity of detached cilia were studied quantitatively. Treatment of mating‐reactive cilia with sodium periodate (NaIO4) markedly decreases mating activity of the cilia. However, the addition of sodium aspartic acid or pre‐treatment with 5% formalin inhibits the NaIO4‐inactivation. This result indicates that the oxidation of some surface components of cilia other than the mating substances is responsible for this inactivation. Five kinds of glycosidases, α‐mannosidase, α‐L‐fucosidase, β‐galactosidase, β‐glucosidase and neuraminidase, have no demonstrable effect on the mating acitivity of the cilia. On the other hand, trypsin destroys the mating activity even in a concentration as low as 0.00001%. These results strongly suggest that no sugar moiety is directly involved in the mating agglutination in P. caudatum.
Inhibition of “spontaneous,” notochord‐induced, and collagen‐induced in vitro somite chondrogenesis by the calcium ionophore, A23187
Authors: Kosher Robert A.
Published: June 2005

The present study represents a first step in investigating the possible involvement of calcium (Ca2+) in the stimulation of somite chondrogenesis elicited by extracellular matrix components produced by the embryonic notochord. The ionophore, A23187, a drug that facilitates Ca2+ uptake leading to elevation of cytoplasmic Ca2+ levels, at concentrations of 0.25–1.0 ug/ml severely impairs “spontaneous” somite chondrogenesis, i.e., inhibits the formation of the small amount of cartilaginous matrix normally formed by embryonic somites in vitro in the absence of inducing tissues. This inhibition is reflected in a considerable reduction in sulfated glycosaminoglycan (GAG) accumulation by A23187‐treated somite explants. Furthermore, A23187 inhibits the striking stimulation of cartilaginous matrix formation and sulfated GAG accumulation normally elicited by the embryonic notochord and collagen substrates. In fact, 1.0 μg/ml of A23187 reduces sulfated GAG accumulation by somites cultured in association with notochord or on collagen to a level even below that accumulated by somites cultured in the absence of these inductive agents. Although these results must be interpreted with caution, they provide incentive for considering a possible regulatory role for Ca2+ in the chondrogenic response of somites to extracellular matrix components produced by the embryonic notochord.
Effects of ecdysterone, inokosterone and eyestalk ablation on limb regeneration in the fiddler crab, Uca pugilator
Authors: Rao K. Ranga
Published: June 2005

Bilateral ablation of eyestalks or injection of either ecdysterone or inokosterone (two 25‐μg doses or five 10‐μg doses into crabs weighing on an average 1.5 g) caused precocious proecdysis and ecdysis in the fiddler crab, Uca pugilator. On a weight basis ecdysterone was more effective than inokosterone in exerting the effects. Whether the accelerated proecdysis was accompanied by regenerative limb growth depended on the degree of limb bud development at the time of treatment with ecdysones. Ecdysterone and inokosterone blocked the initiation of basal limb growth when administered as two 25‐μg doses into crabs exhibiting scar tissue without any visible limb bud. When injected into crabs with limb buds in various stages of basal limb growth exogenous ecdysones accelerated basal limb growth and led to proecdysial limb growth. The degree of acceleration of limb bud growth noticed within three to six days after injection of ecdysones into crabs with limb buds in early stages of basal limb growth was greater than that resulting from eyestalk ablation. In crabs with limb buds in later stages of basal growth, the degree of acceleration of limb bud growth evoked by exogenous ecdysones was similar to that resulting from eyestalk ablation. The final sizes of the limb buds preceding ecdysis in eyestalkless crabs and crabs injected with ecdysones depended on the proecdysial duration available for regeneration.

The rate of proecdysial limb growth has been known to vary with the speed at which the crabs complete the proecdysial stages of the molt cycle. This study shows that the time required for the initiation and completion of the basal limb growth also varies depending on how soon the intact and eyestalkless crabs approach proecdysis and ecdysis.
A correlation between the activity of divalent cation activated adenosine triphosphatase in the cell membrane and low salinity tolerance of the ribbed mussel, Modiolus demissus demissus
Authors: Watts John A. , Pierce Sidney K.
Published: June 2005

A comparison was made between the bound divalent cation stimulated adenosine triphosphatase (ATPase) activity of the cell membrane and the regulation of free amino‐acid (FAA) permeability in the myocardium of the bivalve (Modiolus demissus) during isosmotic and hypoosmotic stress. The FAA efflux induced by isosmotic, divalent cation free, artificial sea water (ASW) was reduced by Ca2+, Mg2+, Mn2+ and Co2+ at concentrations non‐lethal to the intact heart. However, the order of effectiveness in reducing the efflux was not the same as the effectiveness of the divalent cations on the stimulation of ATPase activity. In addition, ATPase activity with the concentrations of Ca2+ and Mg2+ in full strength ASW or in 50% ASW was inhibited by Co2+ and stimulated by Mn2+ Under isosmotic conditions, modification of ATPase activity by Co2+ or Mn2+ did not alter FAA permeability. However, during hypoosmotic stress, the recovery of normal FAA permeability correlated with divalent cation activated ATPase activity; increased enzyme activity in the presence of Mn2+ was coincident with a decreased FAA efflux and decreased enzyme activity in the presence of Co2+ accompanied an increased FAA efflux.

Therefore, the recovery of normal FAA permeability during a hypoosmotic stress is correlated with divalent ATPase activity. During isosmotic conditions, FAA permeability may be controlled by divalent cation binding.
The role of extra cellular material in chick neurulation. II. Surface morphology of neuroepithelial cells during neural fold fusion
Authors: Lee Hsin‐Yi , Sheffield Joel B. , Nagele Robert G.
Published: June 2005

Changes in cell surface morphology of the neuroepithelium during fusion of neural folds in the chick were studied. As the folds were about to meet, a thick extra cellular coat material (ECM) appeared between the two leading edges. Cell membranes forming the fusion area were relatively smooth and heavily coated with ECM. By contrast, the apical surface of most cells lining the wall of the neural tube was folded with much less ECM. During the contact of neural folds, ECM was displaced from the space between the two leading edges, leaving a thin, closely adherent “typical” cell surface coat. Trypsin and concanavalin A inhibited proper alignment and fusion of apposing neural folds by modifying the surface of developing neuroepithelium. Results of this study support a hypothesis that ECM may serve temporarily as an adhesive to bind together the leading edges of neural folds until establishment of more intimate contacts (junctional complexes).
Preconjugant cell‐cell interaction in the ciliate Euplotes crassus: A possible role of the ciliary ampules
Authors: Verni F. , Rosati G. , Luporini P.
Published: June 2005

Euplotes crassus, like other species of Euplotes, possesses organelles commonly known as ampules, which are associated with the roots of cilia and organelles composed of cilia. Ampules of E. crassus greatly increase their functional activity during the cellular interaction which takes place after mixing cells of complementary mating type. Material is rapidly stored in the ampules, starting a few minutes after cell mixing, until a maximum of full ampules is reached in congregated cells which are closely approaching each other. Once the interacting cells have entered the agglutinative stages, the ampules show a dramatic decrease in their contents, so that cells just paired carry very few ampules filled by material.

We infer that the material contained in the ampules has an important role in making the mixed cells competent to unite in pairs.
Estradiol‐17β interference with meiotic maturation in Rana pipiens ovarian follicles: Evidence for inhibition of 3β‐hydroxysteroid dehydrogenase
Authors: Spiegel Judith , Jones Elizabeth , Snyder B. W.
Published: June 2005

Increasing doses of estradiol‐17β added to in vitro incubations inhibited pregnenolone‐induced germinal vesicle breakdown in Rana pipiens ovarian follicles. The inhibition was reversed with increasing concentrations of pregnenolone added to the medium. Because no evidence of estradiol‐17β inhibition or interaction with progesterone‐induced GVBD was observed, the effect of estradiol‐17β on the conversion of 3H‐pregnenolone to 3H‐progesterone was investigated. Estradiol‐17β in doses as low as 10−7 M significantly inhibited the conversion of 3H‐pregnenolone to 3H‐progesterone in follicles incubated in vitro. It is suggested that estradiol‐17β is a feedback inhibitor of 3β‐hydroxysteroid dehydrogenase‐isomerase, the enzyme complex that converts pregnenolone to progesterone, a necessary step in the initiation of GVBD.
Effect of trypsin inhibitors and Concanavalin A on the fertilization of Bufo arenarum coelomic oocytes
Authors: Cabada Marcelo O. , Mariano Marta I. , Raisman Jorge S.
Published: June 2005

The effect of trypsin inhibitors (obtained from soybean, lima bean and ovomucoid) and Concanavalin A on fertilization in Bufo arenarum was tested. In order to study the effect of these substances at the level of the vitelline envelope of the oocytes, a new bioassay was designed. This bioassay employs coelomic oocytes to which some oviducal factors necessary for their fertility was added.

Trypsin inhibitors block both the lytic effect of the acrosomal proteases on the vitelline envelope and fertilization. This indicates that the blockade of fertilization is a consequence of the inhibition of the lytic effect of the acrosomal proteases.

Concanavalin A is effective as well in blocking the lytic effect of acrosomal proteases and fertilization. These effects are reversed by some sugar antagonists of the lectin, thus indicating that the effect of Concanavalin A is through its saccharide‐binding capacity. These results suggested the involvement of glucosidic residues of the vitelline envelope in amphibian fertilization (the saccharide residues might be involved in the attack of the vitelline envelope by the acrosomal proteases).

The possible mechanism of action of these substances is discussed.
Keratogenic metaplasia of the avian chorionic epithelium: Absence of the Beta stratum which characterizes the epidermis of the avian scutellate scale
Authors: Sawyer Roger H.
Published: June 2005

Upon exposure to air, the avian chorionic epithelium (CE) transforms into a keratinizing, stratified squamous epithelium. The overall morphology of this keratogenic CE is unlike any keratinized epidermis of the normal embryo. The basal cells are squamous, not like those of normal avian epidermis which are cuboidal or columnar, and the basal lamina is poorly developed. Although desmosomes are present throughout this keratogenic epithelium, hemidesmosomes do not form in the basal cells. Peridermal and subperidermal layers likewise were not observed. This ultrastructural study does show, however, that the cells of the intermediate layers and stratum corneum resemble very closely those observed in the Alpha Stratum of normal avian epidermis. Yet, in no case does a Beta Stratum characteristic of the normal avian scutellate scale epidermis ever form. Evidently, a rather non‐specific cue can bring about the formation of an Alpha Stratum, whereas induction of a Beta Stratum requires a more specific cue. The hypothesis that the formation of the Beta Stratum of scutellate scales does require a specific dermis and that the dermis itself requires a prior association with an “epidermal placode” is discussed.
Wound healing in tadpole tailfin pieces in vitro
Authors: Derby Albert
Published: June 2005

Explants of tail fins from R. catesbeiana tadpoles undergo reepithelialization of their cut surfaces (healing) when cultured in vitro in Hanks' balanced salt solution at 22°C. Healing is initiated early and closure of the wound is complete by 12 to 24 hours. Morphogenesis continues for several days as further reorganization and migration of epidermal cells from the regions adjacent to the wound margins take place. The addition of serum to the culture media improves the general appearance of these tissues and promotes healing. The rate of healing is affected by temperature. Tail fins maintained at 10°C do not heal while fins maintained at 30° and 37°, although healing more rapidly than at 22°, undergo progressive degeneration in culture.

Epidermal cell movements were also studied in explants consisting of a combination of intact tail fin plus tail fin deprived of its epithelium. Rapid and extensive migration of epidermal cells from the intact tail fin across the collagen lamella of the stripped fin is observed.
Nuclear transplantation in Bombina orientalis and utilization of the Pale mutation as a nuclear marker
Authors: Ellinger Mark S. , Carlson John T.
Published: June 2005

The discoglossid frog, Bombina orientalis, displays many characteristics that make it desirable as a laboratory animal. We report here the first successful transplantation of embryonic nuclei into enucleated eggs of this organism. The participation of the grafted nucleus in the development of the transplant embryos was confirmed with the use of a genetic marker, the Pale mutation. Frogs homozygous for this recessive gene are much lighter in appearance than the wild‐type animals. The use of this trait in appropriate experiments demonstrated that nuclear tansplantation in B. orientalis provides embryos whose nuclei may be reliably interpreted as being derived from the injected nucleus.
Acid base changes during recovery from disturbance and during long term hypoxic exposure in the lobster Homarus vulgaris
Authors: McMahon B. R. , Butler P. J. , Taylor E. W.
Published: June 2005

Hemolymph O2 and CO2 levels and pH were measured in lobsters (H. vulgaris) as they settled in normoxic conditions and during prolonged exposure to moderately hypoxic seawater. Initial handling and transfer to the experimental conditions resulted in a marked acidosis. Complete recovery took from 24 to 48 hours. Samples of hemolymph taken after 48 hours yielded “settled” normoxic levels for O2 CO2 and pH. Subsequent exposure to moderately hypoxic water caused an initial respiratory alkalosis associated with pronounced hyperventilation. The induced pH change was sufficient to cause a marked increase in the oxygen affinity of the hemocyanin, allowing almost complete saturation of post‐branchial (arterial) hemolymph despite a 3‐fold decrease in hemolymph oxygen tension. Prolonged exposure to hypoxia resulted in an attenuation of the hyperventilation response but hemolymph bicarbonate levels rose substantially and may have maintained pH high and thus kept oxygen affinity above the normoxic level. On return to normoxic water both ventilation volume and hemolymph carbon dioxide decreased and pH and oxygen affinity returned to normoxic levels.