摘要:

AbstractHydras cultured for long periods at constant temperature (23°, 21°, 18°, 15°, 10°, or 5°C) were exposed to a new, higher or lower temperature for four weeks.It was found that at constant temperature, the percentage of hydras entering sexuality and the duration of the sexual periods decreased with decreasing temperature. There was no sexual differentiation at 5°.No hydras became sexual within four weeks after a decrease in temperature.The results of the temperature rise experiments show that, in general, the percentage of hydras entering sexuality depended on the absolute temperature change. The results indicate that this percentage also depended on the initial and final temperatures.An hypothesis is presented, accounting for sexual differentiation in terms of a temperature effect on an initiator and an inh

ISSN:0022-104X    

DOI:10.1002/jez.1401600302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractBipolar electrical recordings from the cerebral lobes of chick embryos and of freely moving chicks after hatching indicate that spontaneous electrical activity begins about the eleventh to thirteenth day of incubation, but electroencephalographic patterns characteristic of behavioral sleep or attention appear within six hours after hatching. High amplitude, slow waves, are characteristic of behavioral sleep; low amplitude, fast waves are characteristic of behavioral attention. During sleeping postures the electroencephalographic record shows brief cyclic episodes of lower voltage fast waves (paradoxical sleep) and these cycles appear more definitely as the chick grows older. When the act of waking from sleep is associated with the opening of only one eye, the lower voltage, fast waves may appear only in the contralateral lobe, while the ipsilateral lobe shows the high amplitude slow waves. In the less mature chicks, the electrical waves are slower, less regular, and of smaller amplitude, especially during sleep, furthermore the cyclic episodes of activated sleep are less distinct and the span of attention is more brief. Although chick embryos may move following tactile stimulation, the response is probably due to reflex arcs involving lower nervous centers since the cerebral lobes do not show the transition to lower voltage faster waves characteristic of attention. After hatching electroencephalographic patterns associated with sleeping postures show more conspicuous developmental changes than those associated with attention.

ISSN:0022-104X    

DOI:10.1002/jez.1401600303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractThe effects of bleeding on the short and long‐term iron metabolism of the turtle,Pseudemys scripta elegans, have been determined. Values are given for the plasma radioiron clearance and the clearance constant (K) in normal, bled‐normal and in unbled‐starved turtles. Clearance rates were increased by bleeding but were unaffected by starvation. The rate of the long‐term plasma radioiron clearance (normally slow) was augmented by bleeding in both normal and starved animals. Bleeding increased both the rate and magnitude of erythrocyte radioiron incorporation in normal but not in starved turtles. The distribution of injected59Fe in plasma, erythrocytes, spleen, liver and duodenum is described for normal turtles. The time of availability of injected radioiron for splenic erythropoiesis was about two days, beginning on the second day after administration of the isotope. Storage of iron in the spleen appeared unlikely because of the decrease in spleen radioactivity noted from the fourth day on. This decrease was followed after two days by a similar decrease in circulating erythrocyte radioactivity. From the sixth to the fourteenth days after injection, radioiron moved to the liver and duodenum. It remains to be determined whether this migration represented storage or excretion of t

ISSN:0022-104X    

DOI:10.1002/jez.1401600304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractA repeatable procedure forin vitrofertilization of rabbit ova in which the percentage of ova fertilized is consistently high has been developed. When ova were recovered and subsequently incubatedin vitrowith capacitated spermatozoa at 37° or 39°C levels of ova fertilized were 15, 24 and 28% when 73–78%, 83%, and 90% relative humidities, respectively, were maintained. Twenty‐one per cent of all ova in these experiments were fertilized. When the ova were recovered at 30–39°C and subsequently incubated at 37° or 39°C with capacitated spermatozoa under paraffin oil only 19% of the ova were fertilized. However, when ova were recovered and subsequently incubated with capacitated spermatozoa and fluids from the female tract all under paraffin oil at 39°C with 96–97% relative humidity levels of ova fertilized were 30, 32 and 73% when stored oviduct fluid, stored uterine fluid, and fresh uterine fluid, respectively, were included in the media. Thirty‐seven per cent of all ova incubated with capacitated spermatozoa under paraffin oil were fertilized. This system with the inclusion of fresh uterine fluid in the medium yields the highest percentage of fertilization with greater consistency than any other system forin vitrofertilization of rabbit ov

ISSN:0022-104X    

DOI:10.1002/jez.1401600305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractAn experimental model has been devised for the study of radioactive sulfate incorporation into the cardiac jelly of the isolated stage 18–19 (three‐day) chick embryo heart. Isotope incorporation was found to be optimal in an incubation medium containing glucose, but containing no added unlabeled sulfate. The rate of isotope uptake demonstrated a slight lag during the first 5 to 10 minutes followed by a linear incorporation of at least four hours duration. It is believed that35S‐sulfate incorporation into the hearts reflects sulfated acid mucopolysaccharide synthesis, and that this system will therefore be useful in studying the significance of this group of compounds in the cardiac jelly.Radioactive sulfate incorporation per unit weight has been found to be inversely proportional to heart weight (i.e., embryo age) over the span of development from stage 14 to stage 24. This probably reflects the fact that cardiac jelly makes up proportionately a greater part of the younger hearts.Sodium salicylate has been shown to inhibit35S‐sulfate incorporation in this system, in direct relation to its concentration in the incubation medium. This is given as one example of the type of investigation to which this system is ad

ISSN:0022-104X    

DOI:10.1002/jez.1401600306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractInvestigations of the stage 16 to 19 chick embryo have been performed specifically in relation to the composition of cardiac jelly. Biochemical analysis has demonstrated the presence of a non‐dialyzable sulfated mucopolysaccharide, containing hexosamine and uronic acid. This material can be complexed with cetylpyridinium chloride, and then exhibits differential salt solubility in accordance with known characteristics of acid mucopolysaccharides, suggesting that the chondroitin sulfates and heparin‐like compounds are the major sulfated components. Histochemical and35S‐sulfate incorporation studies also support the interpretation that cardiac jelly contains a significant amount of sulfated acid mucopolysacch

ISSN:0022-104X    

DOI:10.1002/jez.1401600307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractSalivary glands implanted in adult milieu without simultaneous implantation of larval ring glands showed further development and differentiation. The development of the glands was tested by thymidine‐H3and uridine‐H3incorporation in the chromosomes and by proline‐H3incorporation in the cytoplasm. Differentiation was evaluated on the basis of the presence or absence of mucopolysaccharide synthesis in the cells.Chromosomal thymidine incorporation was observed to proceed for a longer period in the adult milieu. DNA measurements revealed that at least in some cells of glands which were implanted at a mid third instar stage the level of polyteny is increased to a level which is never reached during normal development.Glands implanted at a mid third instar stage showed chromosomal uridine incorporation until at least 18 days after implantation.Comparison of the chromosomal puffing patterns in normal and implanted glands revealed that the chromosomes are still able to produce specific puffs after at least three weeks of implantation.In general, glands which were implanted at younger stages of normal development showed a higher response to the adult milieu than glands implanted at a stage near to puparium formation. Also the individual cells of implanted glands showed obvious differences in their response to the adult milieu. It was concluded that the growth and differentiation of the gland cells proceeds but that the regulation and coordination of the processes are disturbed in the adult m

ISSN:0022-104X    

DOI:10.1002/jez.1401600308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractMice bearing intrasplenic ovarian autografts were treated with coumestrol (500 μg/gm diet) and estradiol‐17 β (0.5 μg/day) for 14 days. The splenic grafts of all controls were in various stages of follicular development, whereas some of those receiving estradiol and coumestrol became luteinized. The gonadotropes in the pars distalis of controls were abundant and degranulated. Few PAS‐positive gonadotropes were left after estradiol treatment, showing that the dose used was capable of inhibiting production of gonadotropin. Coumestrol was thought to block release of gonadotropin rather than production since gonadotropes were plentiful and filled with PAS‐positive material.Dietary coumestrol for 10 days at several lower levels produced estrogenic effects on the vagina and uterus of immature mice. However, none of the diets depressed ovarian growth, and it was concluded that no significant inhibition of gonadotropin occurred under these conditions.In general, the results of this study indicate that coumestrol has physiological effects on hypophysial function, relatively large doses are required for antigonadotropic effects, and its primary effect on gonadotropes is to inhibit

ISSN:0022-104X    

DOI:10.1002/jez.1401600309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractThe enzymatic properties and cellular localization of α‐hydroxy acid oxidase have been studied in renal tissue of the rat. The enzyme was most active in the presence of D, L‐ α‐hydroxy valeric acid and D, L‐ α‐hydroxy butyric acid and was inactive in the presence of glycolic acid and D‐alanine. It appeared to have no co‐factor requirement. When subjected to electrophoresis in acrylamide gels, followed by cytochemical development, the enzyme was visualized as a major form accompanied by a minor component. The properties of the major electrophoretic form as determined by cytochemical reaction and densitometric scanning were similar to those determined by quantitative biochemical assay. When subjected to differential centrifugation and density equilibrium centrifugation, particles containing α‐hydroxy acid oxidase sedimented with particles containing D‐amino acid oxidase; α‐hydroxy acid oxidase, therefore, is associated with renal microbodies. The fact that α‐hydroxy acid oxidase transfers electrons to Nitro blue tetrazolium or to Tetra nitro blue tetrazolium made it possible to localize the enzyme by a light microscopic cytochemical procedure. The enzyme was found by this method to be localized predominantly in cells of the proximal tubule. It was present in particles approximately 0.5 μ to 1.0 μ in diameter mainly situated in the basal portions of these cells. These cytochemical preparations probably accurately reflect the cellular distribution of α‐hydroxy acid oxidase and, hence, of those micr

ISSN:0022-104X    

DOI:10.1002/jez.1401600310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY

摘要:

AbstractThe problems at issue concerned the epigenetic responses of chicken embryos to 6‐aminonicotinamide (6‐AN). It had been known that injected 6‐AN is responsible for malformations of the appendicular and facial skeleton (micromelia and parrot beak, respectively) and that the resulting syndrome of malformations resembles the phenotypic features of a number of independent mutations. The questions raised by our tests related to the following problems: Does heterozygosity in one of several of the micromelia‐syndrome transmitting recessive genes alter responsiveness to 6‐AN by raising the incidence of induced micromelia and parrot beak and, on the other hand, does a genotype which had been modified by selection toward low expressivity of the micromelia and parrot beak syndrome, again in heterozygous condition, result in reduced responsiveness to 6‐AN? It is concluded from the results of our test that (a) the genemmAof the California micromelia traits promotes, in single dose, responsiveness to 6‐AN; (b) that multiple modifying genes which tend to suppress thech/chgenotype of Lamoreux's chondrodystrophy greatly reduce, in single dose, the responsiveness of embryos to 6‐AN. It is concluded, finally, that these results satisfy for the micromelia and parrot beak syndrome, induced by 6‐aminonicotinamide, the definition of phenocopy which was implied by the hypothesis from which the present venture started, viz., that the metabolic pathways of gene and induced effect must be sufficiently related to permit interaction d

ISSN:0022-104X    

DOI:10.1002/jez.1401600311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1965

数据来源: WILEY