摘要:

AbstractPlots of the circumference of the hypostome of hydra against the number of tentacles surrounding each hypostome gave a linear relationship. The slope of the line is a characteristic of each species and strain of hydra studied and represents the amount of the circumference of the hypostome relegated to each tentacle. We interpret the intercept on the ordinate of such plots to represent the minimum amount of tissue needed, expressed as circumference of that hypostome, before a first tentacle can form. Hypostomes of newly dropped buds have about the same circumferences as those of adult animals. Diagrams of spacing patterns of tentacles from different species illustrate that the larger the animal, the greater the space between the tentacles. Intertentacular space occupies from 22 to 37% of the hypostome circumferences. The relationship between the average size of the hypostome for a number of groups of hydra and the average size of an animal (measured in micrograms of protein per animal) shows that the size of the hypostome is proportional to the size of the group of hydra being measured, with larger species of hydra having larger hypostomes until a maximum size is reached. We noticed a similar relationship between the part of the circumference of the hypostome occupied to each tentacle vs. animal size. Apparently more hypostomal tissue is allotted to each tentacle in specimens of larger species than to those of smaller ones, and the amount of hypostomal tissue per tentacle reaches a limit regardless of the size of the species.

ISSN:0022-104X    

DOI:10.1002/jez.1402210102

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe tubulin of both brain and testis of the toadBufo arenarumwas partially depolymerized when the animals were maintained on ice for 90 minutes or 17 hours. Recovery of the animals at room temperature restored the normal degree of polymerization in both organs. Normalization of the polymerization degree also occurred in organs separated from cooled animals and incubated in vitro for 90 minutes at 20°C. When the organs were cooled in vitro, only testicular tubulin underwent depolymerization, and in a degree similar to that occurring by incubation at 20°C. The results suggest that the mechanisms regulating tubulin depolymerization in vivo are different from those taking place in vitr

ISSN:0022-104X    

DOI:10.1002/jez.1402210103

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

年代:1982

数据来源: WILEY

摘要:

AbstractMature gemmules were isolated from three individuals of the freshwater sponge,Ephydatia mülleri(Lieberkühn), collected near the termination of the Ottawa River near Montreal, Canada. Following a 4‐month period of vernalization, the gemmule populations were incubated to determine the effects of major environmental variables, temperature, pH, and, photoperiod upon hatching rate and hatchability. The three gemmule populations, each assumed to represent genetically identical clones, exhibited significant variation in hatching rate or hatchability under all incubation conditions, with the exception of total absence of hatching at 5°C. Under a 15L/9D photoperiod, individual differences in hatching rate were detected at all pH levels, and individuals were found to differ in the degree of inhibition of hatching (slowing) at low pH (5.3). Exposure to low pH (6.5‐5.8) at low temperature (5°C) for 1 week resulted in depressed hatching rate and hatchability for all three gemmule populations, with clear differences between populations. The shift of photoperiod to 9L/15D resulted in reduced hatching rate in one population and a slightly increased rate in another. These results demonstrate high genetic and physiological variation within a small local population ofE. mülleri, and suggest that members of this population are differentially sensitive to environmental change‐particularly to relatively minor decrease o

ISSN:0022-104X    

DOI:10.1002/jez.1402210104

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe loci and frequency of conspecific body licking actions of naturally breeding, adult western fence lizards,Sceloporus occidentalis biseriatus, were catalogued and analyzed in an experimental ethogram procedure. The purpose of the study was to begin to localize regions of the western fence lizard body that might exude or carry conspecific chemical signals, or pheromones, important in social encounters of close physical proximity. Among pairs of males, females, and males and females, male stimulus lizards were licked more than stimulus females on (1) the head and face and (2) the flank‐back region, and this was exhibited equally by both male and female experimental lizards (each pair was composed of an experimental and stimulus lizard). Although male and female stimulus animals were licked equally on their legs, experimental females exhibited higher levels of this action than did experimental males. A few tail licks occurred, but no differences of any type were obtained. The results suggest the possibility that pheromones carried on, or exuded from, certain fence lizard body regions, such as the head and face, for example, may play a releasing or eliciting function in social encounters of close physical proximity. Such cues probably are detected by the tongue‐vomeronasal sys

ISSN:0022-104X    

DOI:10.1002/jez.1402210105

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe adjustments of blood respiratory properties to hypoxic conditions (PWO2= 30 Torr) have been investigated in relation to salinity acclimation in the marine prosobranch,Buccinum undatum. (1) In whole blood the reversed Bohr effect and the cooperativity of O2binding are not influenced by acclimation history. (2) Blood from high‐salinity (35%) animals is isoosmotic to the ambient water under normoxic conditions (PWO2= 150 Torr), but hypoosmotic under hypoxic conditions by a regulated decrease in the Cl−ion concentration of about 90 mM. The lower [Cl−] induces, via the reversed Root effect, an approximate doubling of the amount of hemocyanin‐bound oxygen, when blood pCO2is increased in the range 1 to 8 Torr. (3) Blood from low‐salinity (20%) animals is also isoosmotic to the ambient water under hypoxic conditions, and the reversed Root effect is present under both normoxic and hypoxic conditions. (4) At both high and low salinity no change in blood hemocyanin concentration is seen in hypoxiaacclimate

ISSN:0022-104X    

DOI:10.1002/jez.1402210106

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

年代:1982

数据来源: WILEY

摘要:

AbstractA method is described for constructing chimeric hydra that consist of ectoderm from one strain of hydra and endoderm from a different strain. A ring of vitally stained tissue (ectoderm and endoderm) is grafted into an unmarked polyp. Differential movement of the ectoderm and endoderm eventually results in chimeric regions which are visible as marked ectoderm overlying unmarked endoderm and unmarked ectoderm overlying marked endoderm. These chimeric regions are then excised and each is allowed to regenerate, forming a whole chimeric animal. Isolated chimeric regions smaller than 0.5 mm in length were grafted into nitrogen mustard treated animals as hosts for in vivo culturing. Reciprocal chimeras between the40Lstrain ofH. magnipapillata(40L) andH. attenuata(Ha) were used to illustrate the effectiveness of the method for constructing chimeras. These two strains are different in body morphology, size, and color. The [40L ectoderm/Ha endoderm] chimera has40Lshape but is the size and color ofHa. The [Ha ectoderm/40L endoderm] chimera resemblesHain body shape but is the size and color of40L. The stability of these traits indicates that the original parental lineage of the epithelial cells is maintained in the chimeric hydra.

ISSN:0022-104X    

DOI:10.1002/jez.1402210107

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

年代:1982

数据来源: WILEY

摘要:

AbstractLimb regeneration was induced in 4‐day chick embryos by implanting stage 15 neural tube into the amputated stump of the limb. In control animals, amputation alone or amputation with implant of either notochord or somites resulted in development of proximal wing segments only. In experimental animals, more than one‐fourth of the animals containing viable neural tube implants developed proximal, middle, and distal limb segments. These regenerated limb segments contained muscle groups, cartilage models, and nervous structures that approximated the normal situations. Since some new parts regenerated in more than one‐fourth of the cases, it may be concluded that augmentation of nerve supply is an effective method of inducing regeneration in limbs of chick embryos. Volume measurements of the neural tube implant indicate that a “critical mass” of nerve tissue may be necessary for regeneration

ISSN:0022-104X    

DOI:10.1002/jez.1402210108

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe human sperm chromatin was gently decondensed by treating the sperm heads sequentially with micrococcal nuclease and 2 M NaCl. All histones, about 10% of DNA, and a small amount of degraded protamines were released into the soluble fraction, leaving mainly nucleoprotamines in the pellet fraction. Transmission and scanning electron microscopic studies revealed that the nucleoprotamine pellet consisted of chromatin cords of two dimensions, viz., 330‐ to 420‐Å and 650‐ to 1200‐Å thick cords laced together by very fine strands of 60‐ to 80‐Å fibers; both types of cords appeared knobby and had zig‐zag patterns throughout their length. It appeared that these cords were derived from two types of sperm heads of approximately equal population; one type contained chiefly the thick cords and the other chiefly the thin cords. Further treatment of the pelletnuclease‐NaClwith urea and mercaptoethanol resulted in the dissociation of the thick into the thin cords and unravelling of the thin cords into smaller sized fibers; whereas the treatment of the pelletnuclease‐NaClwith DNAase I resulted in the disappearance of the 60‐ to 80‐Å fibers, and the remaining cords were chiefly of thick type together with the sperm head exoskeletons. From these results the packing order of the chromatin in

ISSN:0022-104X    

DOI:10.1002/jez.1402210109

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

年代:1982

数据来源: WILEY

摘要:

AbstractSpontaneous 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 vincristin

ISSN:0022-104X    

DOI:10.1002/jez.1402210110

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe in utero protein synthetic activity of embryos of the western spotted skunk has been examined by one‐dimensional gel electrophoresis and fluorography. The results indicate that delayed‐implanting embryos synthesize a large variety of proteins with molecular weights from200,000. Delayed‐implanting blastocysts synthesize several very large proteinaceous molecules which do not appear to be produced by activated, preimplantation embryos. Activated embryos show increased synthetic activity, but there are many qualitative similarities in the molecular weight profiles characteristic of delay and activated blasto

ISSN:0022-104X    

DOI:10.1002/jez.1402210111

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

年代:1982

数据来源: WILEY