bluuebunny/crossref_metadata_2025 huggingface dataset:
The blastocoelic fluid of sea urchin embryo induces exogastrulation
Authors: Ishihara Katsutoshi , Tonegawa Yasuto , Suyemitsu Takashi , Kubo Hideo
Published: June 2005

The exogastrula‐inducing activity of the blastocoelic fluid of sea urchin embryo was demonstrated by adding it to the culture medium of the late blastula stage. The active substance was separated by gel filtration and ultrafiltration, and its molecular weight was found to be in the range from 10,000 to 50,000. The activity was destroyed by trypsin and heat treatment. Since the treated embryos developed normally into pluteus larvae, except for the extrusion of archenteron toward the outside, the morphogenetic activity of the blastocoelic fluid was assumed to be exerted on the endoderm. Close examination of the exogastrulation process suggests that the evagination was due to some force pushing the endodermal plate toward the outside of the embryo.
Development of peroxisomes in amphibians. I. Cytochemical and biochemical studies on the small intestine
Authors: Dauca M. , Calvert R. , Menard D. , Hugon J. S. , Hourdry J.
Published: June 2005

The ontogeny of intestinal microperoxisomes was studied by cytochemical and biochemical methods during the development of two anuran amphibian species (Rana catesbeiana and Alytes obstetricans). The catalase activity was localized after incubation in DAB medium and studied biochemically by a spectrophotometric method. Microperoxisomes were found to be present in the intestinal epithelial cells of these amphibians. The primary enterocytes of aquatic larvae showed very few microperoxisomes. After metamorphosis the absorptive cells of the new secondary epithelium exhibited a drastically increased number of microperoxisomes per cell section. These organelles showed circular profiles and had a diameter ranging from 0.36 to 0.40 μm. The intestinal catalase activity was low in the tadpoles, increased steadily after metamorphosis, and peaked in the adults. Moreover, at eath developmental stage, the proximal segments always exhibited the highest catalase activity. The present study shows that the number of microperoxisomes as well as the catalase activity increases with the maturation of the intestinal epithelial cells in developing anuran amphibians.
Modalities of the action of temperature on sexual differentiation in field‐developing embryos of the European pond turtle Emys orbicularis (Emydidae)
Authors: Pieau Claude
Published: June 2005

This paper is a study of sex ratios among turtle (Emys orbicularis) hatchlings and young from eggs incubated in the ground, as a function of soil temperature during the gonadal thermosensitive period. Five experiments were performed in Brenne (France) during the summers of 1974, 1975, and 1979. In all these experiments, the sex ratios were found to be skewed. In one experiment, the percentage of males was nearly 50%, whereas the number of females was reduced and the other individuals displayed an intersexual phenotype (the gonads were ovotestes). In the other experiments, the number of males was reduced, whereas the number of females approached 50% or was superior to 50% and the other animals displayed an intersexual (ovotestes) or indeterminate (thin atypical gonads) phenotype. The soil temperature was registered at the same depth as the eggs, and the temperature curves were analyzed for the 12 days following the beginning of the gonadal thermosensitive period (stage 16 of embryonic development). This analysis shows that the first half of this period is the most important for gonadal sexual differentiation. In the first experiment, temperature remained below or surpassed slightly the threshold temperature of 28.5°C (at which males and females, but also intersexes, are obtained). These conditions favored male differentiation. Then, the maxima were higher, allowing female differentiation which was either typical (2 cases of 21 only) or partial (intersexes which are probably genetic females). In the other experiments, the maxima were high, reaching 35 to 40°C, from the very beginning of the thermosensitive period, and although alternating with low minima (inferior to 25°C) they favored female differentiation and inhibited male differentiation. Therefore, intersexes, indeterminates, and probably some phenotypic females would correspond to genetic males.
Twinning and conjoined placentation in mice
Authors: Wan Yu‐Jui , Wu Tsung‐Chieh , Damjanov Ivan
Published: June 2005

Spontaneous and experimentally induced twinning and conjoined placentation were studied in Swiss‐Webster (SW) mice. Conjoined placentation was noticed at a rate of 0.4% for twins and 0.06% for triplets. Placentally conjoined embryos were either symmetrical or asymmetrical. A single spontaneous monozygotic conjoined twin was observed among 2,000 blastocysts cultured in vitro. The yield of twins could not be increased by manipulating explanted embryos in vitro, or by treating in utero during the early postimplantation stage of development with vincristine.
The photo‐gonadal response of a migratory bunting: Evidence of an external coincidence system
Authors: Prasad B. N. , Kumar Vinod , Tewary Reader P. D.
Published: June 2005

Male redheaded buntings (Emberiza bruniceps) were subjected to continuous darkness (DD) or short days (8L/16D) after photo‐stimulation (15L/9D) for either 15 or 30 days. Two groups of birds (four each), after photo‐stimulation for 30 days, were continued on a regimen of 15L/9D. Another two groups (of four each) of photo‐sensitive birds were also subjected to DD or 8L/16D; they served as controls. The effect of transfer to DD or 8L/16D on the size of testes was found not be dependent upon the size attained at the time of transfer. The rate of testicular regression was nearly the same under both the treatments, i.e., in those birds transferred either to DD or to 8L/16D. The birds that were maintained on 15L/9D maintained enlarged testes; this excluded the possibility of the onset of photo‐refractoriness during the treatment period. On the other hand, testes were not photo‐stimulated in the photo‐sensitive birds subjected to DD or 8L/16D. These results are consistent with the Bünning‐Pittendrigh avian external coincidence model, but could be explained alternatively by a relatively simple internal coincidence model. Nevertheless, the application of the law of parsimony suggests the acceptance of the hypothesis of the external coincidence model.
Vagal control of pulmonary blood flow in Ambystoma mexicanum
Authors: De Saint‐Aubain M. L.
Published: June 2005

Through direct observations on Ambystoma mexicanum it is found that the pulmonary artery contracts during stimulation of the vagus nerve and during acetylcholine treatment. In addition, contraction of the artery is a response to lung deflation and also occurs when the vagus fibers from the lung wall are sectioned; lung inflation and atropine treatment produce dilatation of the artery. Hypercapnia and noradrenaline had no effect on pulmonary vasomotor tone. The constrictor is located between the ductus Botalli and the lung, where histological examination showed a concentrically arranged layer of smooth muscle cells. It is suggested that the vagus nerve contains afferent fibers from stretch receptors in the lung wall inhibiting the vasomotor tone in the pulmonary artery. It is further suggested that the pulmonary vasoconstrictor in A. mexicanum is homologous to the vasoconstrictor previously found in a similar location in anurans and reptiles.
Growth, differentiation, and function of the testes in the toad Bufo bufo bufo (L.), with special reference to regulatory capacities: Effects of unilateral castration, hypophysectomy, and excision of bidder's organs
Authors: Barker Jøorgensen C. , Billeter Elisabeth
Published: June 2005

Function and compensatory growth of the testis have been studied in male toads of varying ages, ranging from postmetamorphosis to adults. All experiments lasted 2 months, starting about September 1. Spermatogenesis was normal in sexually immature, 1‐year‐old toads. The fastest growing young toads developed secondary sex characteristics, the thumbpads, during the experiment. The data suggest that size is more influential than age in determining the onset of sexual maturation. But body size is not the only factor which influences sexual maturation. The growth response of the remaining testis to unilateral castration decreased with increasing age and size of the toads. Two months after operation the remaining testis had reached the size of two testes in the young toads, whereas the testis showed no significant compensatory growth in the adultsized toads, wether sexually immature or mature. Hypophysectomy reduced body growth in young toads and prevented a testicular growth response to unilateral castration. Young toads, but not adults, with excised Bidder's organs had larger testes than the control toads. In hypophysectomized, young toads spermatogenesis was still active 2 months after the operation.
Sexual differentiation in Pelmatohydra robusta. I. Response to a temperature change is dependent on the duration of an asexual period after hatching
Authors: Noda Koichi
Published: June 2005

Pelmatohydra robusta were cultured at 18°C in an asexual state for 1‐8 months after hatching and then transferred to 10°C to induce sexual differentiation. When hydra were transferred to the lower temperature within a few months after hatching, they required a much longer time for the formation of mature germ cells than did hydra transferred 6‐8 months after hatching. This indicates that the onset of budding in P. robusta is not always accompanied by sexual maturation. An asexual period of 6‐7 months was required for P. robusta to become sufficiently mature for sexual differentiation. During the asexual period, the growth required for sexual maturation progressed uniformly within a clone, regardless of the budding status of the individual polyps. This indicates that part (or all) of a clone is not rejuvenated by budding.
Mating‐type dependent cell pairing in Oxytricha hymenostoma. IV. Macronuclear DNA content
Authors: Banchetti Rosalba , Cetera Rosanna , Nobili Renzo , Ricci Nicolo , Seyfert Hans‐Martin
Published: June 2005

The cytophotometric study of vegetative cells of Oxytricha hymenostoma showed that the two complementary strains 295 and 301 differ from each other in their macronuclear DNA content: 902 arbitrary units (U) for 295 and 1365 U for 301.

During paraconjugation, a phenomenon involving the total fusion of two complementary partners into a unique, new cellular entity, the macronuclear DNA content/pair does not change strikingly: for the first 3 hr, in fact, the macronuclear DNA content per pair ranges around 2250 U, such a value being very close to that of a 295 cell (902 U) plus that of a 301 cell (1365 U). Only at stages 6 and 7, an increase of the macronuclear DNA content occurs (+9%), which is likely to be due to anomalous replication bands. Finally, at stages 8 and 9, the macronuclear DNA content/pair progressively decreases, dropping to values as small as 2025 U, in spite of the apparently normal replication bands, passing through the macronuclear, soon before the first binary fission of the paraconjugant cell.
Amphotericin B and the elasmobranch rectal gland: Implications for the relationship between oxygen consumption and ion transport
Authors: Shuttleworth T. J.
Published: June 2005

In slices of the dogfish rectal gland, amphotericin B produced increases in oxygen consumption and ouabain binding similar to those produced by cyclic AMP, except that the increases induced by the latter were inhibited by furosemide whereas those resulting from the addition of amphotericin B were unaffected by the diuretic. Unlike cyclic AMP, however, amphotericin B failed to stimulate secretion by the isolated perfused gland. These results support the suggestion that the increases in ouabain binding and oxygen consumption produced by cyclic AMP result simply from an increased sodium entry into the cells, and as such can be mimicked by amphotericin B, whereas secretion rate itself depends on some additional, cyclic AMP‐induced process. The implications of this for determinations of the relationship between rates of oxygen consumption and ion transport are discussed.
A biochemical and morphological investigation of alkaline phosphatase and Ca+2‐ATPase during initial mineralization in chick embryonic tibia
Authors: Sandhu Harinder S. , Jande Sohan S.
Published: June 2005

Biochemical analysis of the enzymes alkaline phosphatase and Ca+2‐ATPase in the membrane fraction obtained from chick embryonic tibias showed a positive correlation between the elevated activity of these two enzymes and the onset of mineralization. Histochemistry further showed an increased intensity of alkaline phosphatase at the time of the onset of mineralization. It seems that both of these enzymes are involved in the process of mineralization.
Glycogen, protein, and lipid content of green, aposymbiotic, and nonsymbiotic hydra during starvation
Authors: Cook Clayton B. , Kelty Marcia O.
Published: June 2005

Glycogen and protein levels during starvation were determined for symbiotic and aposymbiotic Hydra viridis, and for a brown hydra, H. littoralis. Glycogen content in green hydra increased over a 2‐week period; this appears to be the first report of an animal which accumulates a food reserve during prolonged starvation. These hydra also retained a greater proportion of tissue protein than either of the other groups. Relative utilization of glycogen was similar in aposymbiotic and brown hydra, although initial glycogen stores of brown hydra were ten times larger. Aposymbionts had a proportionately higher rate of protein loss than brown hydra. Food reserves of starving green hydra are augmented by photosynthetic products of symbiotic algae, while starving brown hydra rely on large stores of all reserves, including lipids.
Suppression of male pronuclear movement in frog eggs by hydrostatic pressure and deuterium oxide yields androgenetic haploids
Authors: Briedis Andris , Elinson Richard P.
Published: June 2005

The disruptive effects of microtubule‐specific agents on pronuclear movement illustrate the requirement of an intact cytoskeletal system for movement. In this study, we investigated the effects of high hydrostatic pressure and deuterium oxide (D2O) on fertilized Rana pipiens eggs during the time of pronuclear migration. The eggs were either pulsed for six min with 3000, 5000, or 7000 psi or placed for ten min in 80% D2O between the time of second polar body emission and first cleavage. Both treatments disrupted male pronuclear migration as shown by eccentric first cleavage furrows. Treatment of eggs prior to pronuclear association resulted in haploid production. The androgenetic origin of the haploid embryos was demonstrated using morphological and isozymal markers produced by the cross Rana pipiens ♀ × Rana utricularia ♂. Eggs treated with D2O also yielded embryos with neural defects identical to those following ultraviolet irradiation. This study complements the recent reports on pressure‐suppression of the second polar body and of first cleavage by showing that the selective suppression of microtubular function between these two events produces an entirely different set of genetic and developmental consequences.
Nonuniform distribution of enzymes in fish eggs
Authors: Klyachko Olga S. , Korzh Vladimir P. , Gorgolyuk Sofia I. , Timofeev Andrei V. , Neyfakh Alexander A.
Published: June 2005

The distribution of enzymes in the blastoderm and the yolk was investigated in the eggs of the bony fish, Misgurnus fossilis. The total activities of lactate dehydrogenase (LDH), glucose‐6‐phosphate dehydrogenase (G‐6‐PD), and aldolase (ALD) did not change during early development. However, the enzymes were redistributed in the egg: at the blastula stage the blastoderm contains about 60% of the total ALD activity and 80% of the total LDH and G‐6‐PD activities.

The “free cytoplasm” volume, in which the enzymic proteins can be solubilized, is greater in the yolk than in the blastoderm. Low levels of homologous enzymes from other species injected into the egg are distributed between the blastoderm and the yolk in the same way as are the native enzymes; they are primarily localized in the blastoderm. Injected exogenous enzyme concentrates preferentially in the yolk, apparently being distributed proportionately with respect to the “free cytoplasm” volumes. The ratio of these “free cytoplasmic” volumes, determined by distribution of the injected enzyme (LDH), in the yolk and in the blastoderm is 6.8. On the basis of our results we propose that many egg enzymes are noncovalently bound to blastoderm structures, and that the “nonbound” fraction of the enzymes in the cytosol is distributed proportionally to the “free cytoplasm” volumes in the blastoderm and in the yolk.

Fractionation of the subcellular constituents of blastoderm extracts by ultracentrifugation or by gel filtration on Sepharose in the presence of an excess of LDH reveals the high‐molecular weight LDH‐containing complexes. These complexes are absent in the yolk and in the unfertilized eggs. These results are consistent with the hypothesis that the binding of the enzyme to subcellular structures in the blastoderm is an important mechanism in ooplasmic segregation.
Cuticle ultrastructure with respect to the lipid waterproofing barrier
Authors: Hadley Neil F.
Published: June 2005

Lipids (waxes) deposited on or incorporated in the epicuticle provide an important waterproofing barrier in most terrestrial insects and arachnids. Although the chemical nature of these lipids is well documented, ultra‐structural evidence for their association with specific cuticular layers and sublayers is less conclusive. Difficulties here include relating layers observed with the electron microscope with layers seen under light microscopy, plus the fact that much lipid is removed in normal preparative procedures for electron microscopy. Moreover, epicuticular layers which presumably are lipid‐rich are often resistant to organic solvents. The latter suggests that if lipid is present, much of it is bound, possibly to protein. Preliminary studies using new techniques such as myrcene partitioning and freeze‐fracture microscopy which improve lipid rétention and visualization have yielded some promising results. Scanning electron microscopy of surface waxes, in contrast, has revealed complex lipid accumulations which can be altered or removed by appropriate organic solvents. Surface waxes no doubt supplement lipids associated with epicuticular layers in restricting water loss, with the effectiveness of the former being dependent upon their thickness, physical structure and arrangement, and their chemical composition. Pore and wax canals are likely the major routes via which lipids are transported from sites of synthesis to the epicuticle, but the exact mechanisms involved must still be resolved.
A new system for concurrent measurement of respiration and water loss in arthropods
Authors: Quinlan Michael C. , Hadley Neil F.
Published: June 2005

A new, flow‐through system for the concurrent measurement of water loss and CO2 production from arthropods is described. The system employs an Al2O3 sensor to measure the moisture content of the air stream, and an infrared gas analyzer to determine the CO2 content. The system responds rapidly, is accurate, and provides a continuous record of both variables at constant or increasing temperatures. Preliminary studies on the house cricket, Acheta domesticus, showed that water loss and V̇ were highly variable depending upon the activity of crickets and that water loss increased greatly as a result of oral and anal discharges of fluid. Occlusion of the mouth and anus (paraffin) reduced water loss and V̇ at 30°C by 82 and 46%, respectively. Strong correlations between V̇ and water loss were observed in crickets whose mouth and anus had been sealed, both in long‐term (3 hour) isothermal studies and under conditions of rapidly increasing temperature.
Physiological processes related to nitrogen excretion in cockroaches
Authors: Cochran Donald G. , Mullins Donald E.
Published: June 2005

Several patterns of uric acid voiding exist among various cockroach species. The impact of dietary nitrogen levels on these patterns has now been examined. Blattella germanica, Supella longipalpa, and Latiblattella inornata do not void uric acid even when maintained on diets containing 10.6% nitrogen for up to 30 days. Two species of Nahublattella void some uric acid on that diet, but high mortality was observed by 15 days. Parcoblatta fulvescens voids increasing amounts of uric acid as formed pellets when dietary nitrogen is increased, and suffers no untoward effects. The partitioning of injected 14C‐purine (hypoxanthine) by Parcoblatta was shown to occur first by conversion to 14C‐uric acid. Thereafter, 14C is found in evolved 14CO2, feces, egg cases, and whole body. The partitioning of 14C is influenced by the level of dietary nitrogen available. On a nitrogen‐restricted diet, larger amounts of 14CO2 are evolved but little 14C occurs in the feces. When nitrogen is abundant, reduced amounts of 14CO2 are evolved and more 14C is voided with the feces. 14C‐containing compounds, including 14C‐uric acid, are incorporated into egg cases. Radiolabel remaining in the injected insects at the end of the experiment was also influenced by the dietary regime. These results are discussed in relation to the flow of uric acid through Parcoblatta and its utilization by this insect.
Novel uptake systems for atmospheric water vapor among insects
Authors: Rudolph Dieter , Knülle Willi
Published: June 2005

Uptake of water vapor from subsaturated atmospheres in the Psocodea is accomplished by an oral device. During uptake paired lingual sclerites of the ventral hypopharynx are brought into a typical absorbing position. Vapor condensation proceeds onto a fluid layer covering this surface. This fluid presumably originates from a pair of dorsal labial glands. The condensed vapor is transferred from the site of condensation to the entrace of the gut via a sclerotized tubule traversing the hypopharynx. Propulsion of the fluid is achieved by a cibarial sucking pump which operates intermittently. Below the critical equilibrium humidity (CEH) the fluid layer dries up, the salivarium is closed, and uptake of vapor ceases. Uptake of water vapor is a feature common to the whole order Psocoptera and is apparently not related to specific environmental conditions. Among the ectoparasitic descendants from the Psocopteran stock the absorbing system is preserved in both groups of the Mallophaga (Amblycera and Ischnocera); the faculty has, however, been lost independently by single species in both lines. In these species structural components of the uptake device are modified or reduced. The faculty appears to be completely absent in the Anoplura. The distribution of vapor uptake among the Phthiraptera is neither correlated with the type of host nor the mode of nutrition. The CEHs of the Mallophagans (43 to 52% relative humidity: R. H.) are markedly lower than those of the Psocoptera (58 to 85% R. H.). The uptake rates of most Mallophagans are extraordinarily high. A novel case of anal vapor uptake is reported in flea larvae and a preliminary account of rectal structures, possibly involved in vapor uptake, is given.
Physiological and psychophysical spectral sensitivities of the cichlid fish, Hemichromis bimaculatus
Authors: Bell David M.
Published: June 2005

Electrophysiological and psychophysical spectral sensitivities of the teleost Hemichromis bimaculatus (Pisces; Cichlidae) were determined by measurement of electroretinogram b‐wave magnitude and optomotor response threshold. The physiological and behavioral curves exhibit trivariance and trichromacy, respectively, with peaks occurring in the 460–478, 546, and 623–646 nm spectral regions. A 20‐nm shift to the red is seen in the physiological curves upon strong light adaptation, accompanied by an order of magnitude decline in overall sensitivity. Photopic physiological and behavioral sensitivities correspond in sensitivity, but differ in dominant peaks, with the red and green spectral sensitivities dominating the respective curves. The common spectral peaks correspond with suspected vertebrate photopigments, correlate with the visually oriented nuptial and parental behaviors of the cichlids, and imply cone dominance in the retina of this teleost.
Photoperiodic regulation of the gonadal recrudescence in common Indian Rosefinch: Dependence on circadian rhythms
Authors: Kumar Vinod , Tewary P. D.
Published: June 2005

Male Rosefinches, previously treated with short days (8L: 16D), were held under six different light regimes (resonance light cycles) in which a main 6‐hr photophase was combined with varying durations of scotophases (6L/6(2n + l)D)

L, light phase; D, dark phase; n, number of multiples of 6D.

; one group was also placed under long days (15L:9D) which served as control. Birds placed under long days as well as 6L:6D, 6L:30D, 6L:54D showed complete gonadal growthand development, while birds under 6L:18D, 6L:42D, 6L:66D showed no testicular growth and behaved as if they had been exposed to short days. These results are consistent with the Bünning hypothesis and indicate that the photoperiodic time measurement in Common Indian Rosefinches (Carpodacus erythrinus) involves an endogenous rhythm of approximately 24 hr in duration.
Pattern regulation between hind‐ and forelimbs after blastema exchanges and skin grafts in Notophthalmus viridescens
Authors: Rollman‐Dinsmore Christine , Bryant Susan V.
Published: June 2005

Experiments were performed to ascertain whether cells from the forelimb and the hindlimb of newts share a common pattern‐regulating mechanism during regeneration. In one series of experiments early digit hindlimb and forelimb blastemas were exchanged either ipsilaterally or contralaterally. In a second experimental series, a strip of forelimb skin was added to a slit in a homologous site on the hindlimb or in a site 180° removed from the position of origin, and vice versa (hindlimb skin into forelimb). After contralateral blastema exchanges, supernumerary limbs developed in addition to the limb of graft origin, whereas after ipsilateral exchanges, a single limb of graft origin regenerated. Limbs in which skin grafts were inserted into homologous sites developed normal regenerates of the host type, while in contrast, limbs with supernumerary digits regenerated from limbs which had received skin grafts in positions 180° opposite to the homologous position. The results of both experiments were dependent on the positional disparity between the graft and host tissues, and they suggest that the forelimb and hindlimb do indeed utilize a common mechanism for pattern regulation.
Timing of gastrulation in fused double‐embryos formed from eggs with different cleavage schedules in the starfish, Asterina pectinifera
Authors: Mita I. , Satoh N.
Published: June 2005

The aim of this study is to explore the control mechanism which regulates, the timing of gastrulation. We wished to know whether the timing is rigidly determined within the constituting cells of the embryo or whether it is changed by intercellular communication systems. Starfish‐fused double‐embryos were formed by contact between pairs of denuded eggs with different cleavage schedules, one egg in each pair being distinguished with vital stain. Electron microscopy revealed identical ultrastructural characteristics in every cell contact: Septate junctions were found not only between cells in the contact area between the two counterparts constituting a fused embryo but also between cells within a counterpart. In fused embryos formed from stained eggs and unstained eggs with the former having started the first cleavage 30 min earlier than the latter, the stained counterparts began to invaginate about 30 min earlier than the unstained. When fused embryos were produced by putting stained eggs in contact with unstained eggs which had begun the first cleavage 2 hr later than the stained eggs, gastrulation of the stained counterparts took place about 2 hr earlier than that of the unstained counterparts. These results suggest that the timing of gastrulation is fixed within the cells of an embryo and cannot be altered in spite of the cell‐to‐cell communication that appears to exist.
The effect of sperm concentrations during preincubation and at insemination on fertilization of rat eggs in vitro
Authors: Nishimura H. , Niwa K. , Miyake M. , Iritani A.
Published: June 2005

Rat epididymal spermatozoa, at a concentration of 40–65 × 104 cells/ml, were preincubated for 5–5.5 hr and then added to eggs from superovu‐lated, immature rats. By 10–12 hr after insemination, 86% of the eggs had undergone fertilization, but many of them (41%) were polyspermic. When sperm were preincubated at almost the same concentration and for the time stated above, but then diluted to 1–3 × 104 cells/ml before insemination, the number of fertilized eggs and the incidence of polyspermy were both reduced, being 56% and 5%, respectively. When a sperm concentration of 1–3 × 104 cells/ml was used both during preincubation and at insemination, the fertilization rate and the degree of polyspermy were essentially zero. To achieve a fertilization rate of 60% or more, with polyspermy not in excess of 10%, a sperm concentration of 30–100 × 104 cells/ml during preincubation and then diluted to approximately 1–3 × 104 cells/ml at insemination appears to be optimal.
The effects of antisperm plasma membrane antibodies on sperm‐egg binding, penetration, and fertilization in the pig
Authors: Peterson R. N. , Robl J. M. , Dziuk P. J. , Russell L. D.
Published: June 2005

A procedure using published surgical techniques is described for determining the effects of antiplasma membrane antibodies on sperm‐egg binding, penetration, and fertilization in vivo in the domestic pig. Time of ovulation was controlled and sperm inseminated at precise times relative to ovulation. Sperm were exposed to antibodies (Fab) and then washed free of excess antibody and placed in one uterine horn near the uterotubal junction. Sperm exposed to control material were placed in the opposite horn as a control. One horn was tied with two ligatures near the body of the uterus. Eggs were collected by flushing the oviducts at prescribed times after insemination. In nine animals used for this study, antibodies to boar sperm plasma membranes completely blocked sperm‐zona binding, penetration of the zona, and fertilization. In contrast, sperm were bound to the zona pellucida and penetrated eggs in every case on the control side. These results indicate that insemination in vivo is useful in screening antibodies produced against specific plasma membrane antigens to determine their role in fertilization.
Taurine transport by isolated flounder renal tubules
Authors: King Patricia A. , Beyenbach Klaus W. , Goldstein Leon
Published: June 2005

Previous in vivo clearance studies (Schrock et al., '82) have revealed that taurine is secreted by marine fish kidneys. In the present study taurine secretion by the flounder (Pseudopleuronectes americanus) renal tubule was investigated by assaying the transport of 14C‐taurine in vitro. Collections from isolated fluid‐secreting flounder tubules confirmed the presence of a tubular mechanism for taurine secretion. The flounder renal tubule concentrated taurine in the lumen at a lumen/bath ratio of 25, with the movement across the peritubular membrane identified as the concentrating step of taurine transport. Studies with teased flounder renal tubules identified transport as Na+ and Cl− dependent. Taurine transport was inhibited by β alanine, γ‐aminobutyric acid, and hypotaurine. In a study of the hormonal control of taurine transport, only the adrenal steroid dexamethasone stimulated taurine uptake by the flounder renal tubules. Transport was not affected by the second messengers adenosine 3′5′‐ cyclic monophosphate, guanosine 3′5′‐cyclic monophosphate, adenosine, or Ca++ ionophore (A12384).
Studies of mitosis in excised limb regenerates of the newt, Notophthalmus viridescens
Authors: Tomlinson B. L. , Globus M. , Vethamany‐Globus S.
Published: June 2005

Subsequent to excision and explantation of the limb blastema into culture medium, there is an abrupt reduction in mitotic index lasting several hours. Coincident with the disappearance of mitosis, abnormal mitotic figures (AMFs), lacking the condensed chromosomal nature of normal figures, are seen. These persist until normal levels of mitotic activity are restored approximately 6 hr later. The transient loss of mitotic activity is observed in both ganglionated and nonganglionated explants. The large number of prophase figures observed at time zero were sharply reduced within minutes, without concomitant increases in the later phases. The possibility that some cells, without completing mitosis, become temporarily indistinguishable as mitotic figures, is discussed in terms of chromosomal decondensation and recondensation.
Culture of 9½‐day rat embryos in human serum supplemented and unsupplemented with rat serum
Authors: Reti Leslie L. , Beck Felix , Bulman Stephanie
Published: June 2005

We attempted to grow explanted 9½‐day rat embryos in vitro in human serum but were unable to demonstrate normal growth as has been previously described. The embryos were consistently smaller, anaemic, and frequently deformed. These abnormalities were overcome by supplementing the human serum with 10% rat serum. The latter possibly provides yet unidentified essential growth factors required by rat embryos that are not present in human serum.
Inhibition of vacuolar membrane fusion by intracellular symbiotic algae in Hydra viridis (Florida strain)
Authors: O'Brien Timothy L.
Published: June 2005

Hydra viridis (Florida strain) forms a stable symbiotic association with unicellular Chlorella‐like algae. Algae are phagocytized by hydra phagocytes and maintained individually within vacuoles of the host‐cell. The purpose of the studies presented in this paper was to determine how symbiotic algae avoid host‐cell digestive processes. Viable symbiotic algae were found to inhibit the fusion of the algal vacuolar membrane and vacuoles labeled with thorium dioxide. By contrast, thorium‐labeled vacuoles did fuse with vacuoles containing nonviable algae. Further, the absence of acid phosphatase activity within vacuoles containing established symbiotic algae implies that inhibition of membrane fusion by algae in hydras prevents the conversion of the algal vacuoles into phagolysosomes.
The program of Hl histone synthesis in S. purpuratus embryos and the control of its timing
Authors: Harrison M. Frances , Wilt Fred H.
Published: June 2005

The program of H1 histone synthesis was investigated in Strongylocentrotus purpuratus embryos in order to determine when the late Hl histones are synthesized. The embryos were staged by cell number, morphological stage, and chronological age. Care was taken to ensure that conditions of rearing the embryos remained consistent. Labelling with 3H‐lysine revealed that two forms of early Hl (Hlα1, and Hlα2) are synthesized from early cleavage stages (16–32 cells) to the blastula stage. Hlα1, synthesis ceases first at around 400 cells (hatching blastula); Hlα2 continues to be synthesized by the blastula but is usually absent from the labelling pattern in early gastrula (700 cells). Two forms of late Hl γ appear sequentially during the pre‐hatching blastula stage. Hl γ appears at 200–250 cells and Hl β approximately 1 hr later, at 250–300 cells. The late forms of H2A and H2B are first synthesized at around hatching, several hours after late Hl forms appear. The time of synthesis of late Hl is strictly controlled by a chronological clock and is not affected by disruption of the cell cycle, cessation of DNA synthesis, or alteration of nucleocytoplasmic ratios. Polyspermic embryos and hydroxyurea‐arrested embryos followed the normal temporal program of on‐ set of late Hl synthesis.
Genes involved in regulating the melanocyte and melanoblast‐melanocyte populations in the epidermis of newborn mouse skin
Authors: Hirobe Tomohisa
Published: June 2005

In the dorsal epidermis of both C57BL/10J and C3H/He mice, the number of melanocytes positive to the dopa reaction increased from birth to 3 or 4 days of age, and then gradually decreased and disappeared by 30 days of age. However, the number of melanoblasts plus melanocytes positive to the combined dopa‐premelanin reaction remained constant until 3 or 4 days of age and then decreased in both strains. Despite the similarity of the change in these populations from birth on, there was a significant difference in the number of such cells between the two strains. Both melanocytes and melanoblasts in C3H/He were fewer than in C57BL/10J mice.

The F1, F2, and backcross matings were performed in order to gain some information about the genetic basis of the difference. In the F1 generation the offspring from reciprocal crosses exhibited intermediate values in both populations. The F2 generation included the C3H/He type, F1 type, and C57BL/10J type in a ratio of about 1:2:1 in both populations. Moreover, both reciprocal backcrosses gave ratios of parent type to F1 type, which did not differ significantly from 1:1 in either population. These results indicate that the melanocyte and melanoblast‐melanocyte populations in the dorsal epidermis of newborn mouse skin are controlled by semidominant genes.
In vitro synthesis and secretion of ecdysteroids by Drosophila melanogaster ovaries
Authors: Rubenstein Elaine C. , Kelly Thomas J. , Schwartz Margaret B. , Woods Charles W.
Published: June 2005

The ovaries of adult Drosophila melanogaster were shown to produce and secrete ecdysteroids in vitro by an ecdysteroid radioimmunoassay. The major secretory products were determined by HPLC/RIA analysis to be ecdysone, 20‐hydroxyecdysone, and a highly polar fraction. Based on competitive binding studies, the secreted ecdysteroids contain 2–3 times more 20‐hydroxyecdysone than ecdysone.
The leg flexor muscle of Carcinus. I. Innervation and excitatory neuromuscular physiology
Authors: Parsons D. W.
Published: June 2005

The innervation and neuromuscular physiology of the flexor muscles in the legs of Carcinus were investigated using a variety of histological and electrophysiological techniques. Slow muscle fibers were found in the proximal and distal regions of the muscle; intermediate‐ and fast‐contracting fibers were found in most regions, but fast fibers predominated in the central regions. Muscle fibers were innervated by one to four excitatory axons. The extent of inhibitory innervation was not determined. The motor innervation showed significant departures from the previously described Brachyuran pattern. The results indicated the need for a thorough reexamination of the patterns of limb innervation of the crustacean tribes.
Comparison of antifreeze glycopeptides from arctic and antarctic fishes
Authors: O'Grady Scott M. , Schrag Joseph D. , Raymond James A. , Devries Arthur L.
Published: June 2005

Antifreeze glycopeptides from the Atlantic tomcod Microgadus tomcod), saffron cod (Eleginus gracilis), and Greenland cod (Gadus ogac) were isolated by ion exchange chromatography. Polyacrylamide gel electrophoresis revealed that fewer sizes of antifreeze glycopeptides are present in the serum of M. tomcod and E. gracilis compared to the Antarctic nototheniid (Dissostichus mawsoni), Glycopeptide 6 from M. tomcod and E. gracilis as well as glycopeptide 8 from G. ogac were sequenced and compared with known sequences of similar‐sized glycopeptides from Antarctic fishes. It was found that arginine residues in glycopeptide 6 from E. gracilis and M. tomcod occur at positions 15 and 18, that proline periodically replaces alanine (ala) at positions 7, 13, and 19. In contrast, none of the antifreeze glycopeptides from Antarctic fishes contain arginine. Threonine (thr) occupies positions 15 and 18 instead. Glycopeptide 8 from G. ogac was found to have the same sequence as glycopeptide 8 from the polar cod (Boreogadus saida). The results indicate that the repeating sequence (ala‐ala‐thr) appears to be highly conserved within polar fishes. However, greater variation in antifreeze glycopeptide structure exists within one family of northern cods (Gadidae) than within species belonging to four separate families of Antarctic fishes.
Quail nuclear marker is lost during in vitro culture
Authors: Yaross Marcia S. , Konigsberg Irwin R.
Published: June 2005

Japanese quail cells when cultured in vitro lose the characteristic nuclear morphology that distinguishes them from chick cells. To determine if the nuclear marker is regained if cultured cells are reimplanted in ovo, a double marker experiment was performed. Quail neural crest cells, which include melanocyte precursors, were cultured in vitro and implanted into chick embryos. Although many of the resulting quail melanocytes exhibit the characteristic quail morphology, others do not. Thus, if donor cells are cultured in vitro prior to transplantation into chick hosts, the possibility that cells of quail origin are present but indistinguishable from host tissue must be considered.
The effect of the dorsal region in reversed orientation on the development of the embryonic chick wing
Authors: Searls Robert L.
Published: June 2005

Dorsal right wing myogenic mesoderm, with or without ectoderm, that had been labeled with tritiated thymidine, was grafted into the dorsal right wing myogenic region in reversed proximal‐distal and cranial‐caudal orientation. When a graft of ectoderm and mesoderm was in reversed orientation, the graft increased in length, width, and thickness. A similar graft in normal orientation increased only on the axis of the humerus. A graft of mesoderm alone in reversed orientation increased in length and thickness, like a graft in normal orientation, but increased in width like a graft of ectoderm and mesoderm in reversed orientation. During normal wing development, a groove develops at the base of the wing ventral to the ninteenth somite due to the ventral movement of the lateral body wall proximal to the base of the wing. A graft in normal orientation participated in the formation of the groove if placed in a position where it was appropriate to do so. A graft in reversed orientation did not participate in the formation of the groove, although it did not block the ventral movement of the lateral body wall proximal to the base of the wing. When the groove did not form, the humerus did not separate from the lateral body wall and the humerus was short. Increase in size of the graft in inappropriate directions caused grafted myogenic cells to be present in inappropriate amounts and locations. Ectopic cartilage differentiated from the grafted cells present in inappropriate locations.
Acceleration of acrosome reaction in hamster spermatozoa by lysolecithin
Authors: Ohzu Eiji , Yanagimachi Ryuzo
Published: June 2005

When hamster spermatozoa were preincubated for 1–2 hr in Ca2+‐containing medium and then exposed to lysolecithin (LC), large proportions of the spermatozoa underwent acrosome reactions within 15 min. These acrosome‐reacted spermatozoa were capable of fertilizing eggs. The earliest visible sign of the reaction, wrinkling of the acrosomal cap, seen by 30 sec after exposure to LC. The reaction in many spermatozoa was completed within the next 30 sec.
Volume regulation in an intertidal nemertine, Procephalothrix spiralis coe. I. Short‐term effects and independence of decerebration
Authors: Ferraris Joan D. , Schmidt‐Nielsen Bodil
Published: June 2005

In the Nemertina both neurosecretory cells in the cerebral ganglia and neuroglandular structures (cephalic glands and cerebral organs) have been found to be responsive, on a cytological level, to changes in the osmolality of the worm's environment. However, the volume or osmoregulatory capacities of these worms are scarcely known. The present study examines water, ion, and volume regulation in an intertidal nemertine and the effects of removal of the cerebral ganglia and the cephalic glands on these parameters.

Control, sham‐operated, and decerebrated (ablated) Procephalothrix spiralis were acutely transferred to diluted seawaters. Osmolality and Na, K, and Cl (mEq/liter) concentrations were determined in total tissue water after various exposure periods. Extracellular volume was determined, in vitro, as the fraction of the total tissue water in which 14C‐polyethylene glycol was distributed.

Control, sham‐operated, and ablated P. spiralis all responded to diluted seawaters in the same manner with no significant difference among groups. In diluted media, the worms demonstrated hyperosmotic conformity. Tissue osmolality decreased rapidly in all groups at similar rates indicating no effect of ablation on integumental water permeability. Significant volume regulatory responses were observed in all worms starting 15 minutes after exposure. Based on the very small extracellular volume (∼5% of total body water) of P. spiralis, measured volume regulatory events in this species primarily reflect intracellular phenomena. Initially, osmolality decreased while water content (gm H20/gm solute free dry weight) increased. During this period, volume regulation was accomplished by the elimination of Na, Cl, and unmeasured solutes (μmoles or μosmoles/gm s.f.d.w.) which limited water gain. Subsequently, osmolality was constant and all worms demonstrated a slow regulatory volume decrease. The solutes that accompanied volume loss were also Na, Cl, and substantial amounts of unmeasured solutes.
Cyclic nucleotides during chondrogenesis: Concentration and distribution in vivo and in vitro
Authors: Ho Wai Chang , Greene Robert M. , Shanfeld Joseph , Davidovitch Z.
Published: June 2005

This study correlates endogenous levels of cAMP and cGMP with their immunohistochemical localization during chondrogenic differentiation of C57B1/6J mouse limb mesenchyme in vivo and in vitro. A transient decrease in cGMP but not cAMP was found from days 12 to 13 in vivo correlating with early stages of chondrogenesis in the developing limb. Intracellular levels of both cAMP and cGMP in high density limb mesenchyme cultures increased 25% after 24 hr in culture when aggregate and nodule formation was detectable. When cells were seeded at different initial plating densities to delay the onset of aggregate and nodule formation, increased levels of intracellular cAM Pcorrelated temporally with the appearance of nodules. Both cyclic AMP and cGMP were immunohistochemically localized in perichondrial cells and chondrocytes in vivo and in vitro. Therefore, (1) cAMP levels correlated temporally with the appearance of chondrogenic cells and (2) cAMP and cGMP were immunohistochemically localized to chondrogenic cells.

These data indicate that fluctuations of both cAMP and cGMP levels may be involved in limb cartilage differentiation. Although increases in both nucleotides were found to correlate with the onset of chondrogenesis in vitro, in vivo data suggest that the amount of cAMP relative to cGMP rather than the absolute amount of an individual cyclic nucleotide may be more significant in modulating differentiation.