摘要:

AbstractElution patterns of sperm chemo‐attractants isolated from female hydroids of the generaCampanularia, Gonothyrea, TubulariaandClavawere obtained by comparative gel filtration chromatography. Generally one major and one minor peak of activity were obtained for each of the species used, exceptGonothyreawhich yielded two large active peaks. The Rf values of these peaks fall into two non‐overlapping groups. The first group consists of the major peak obtained fromCampanularia calceolifera, the first major peak fromGonothyreaand the minor peak obtained from each of the three species ofTubularia, all of which have Rf values near 0.7. The second group consists of the major peaks from the three species ofTubularia, the second major peak fromGonothyrea, the minor peak fromC. calceolifera, and the major peak fromClava, all of which have Rf values near 0.5. Separation of mixtures of some of the attractants was possible using this method.Correlation between chromatographic elution position and species‐specificity determined by testing the extracts from the various species against live sperm, is not perfect in all cases, in part, at least, because gel filtration is not capable of separations other than on the crude basis of molecular size.GonothyreaandCampanularia calceoliferaextracts and sperm show cross‐reactivity and their active agents elute together during chromatography. The same is true for the three species ofTubulariatested. However, the secondGonothyreapeak elutes at the same position as the major peak ofTubulariaactivity, but these genera do not attract each other's sperm. These results suggest that methods other than chemotaxis are used by many hydroids to prevent exposure of eggs to sperm from the wrong species and that more specific separation methods will have to be used to determine the molecular basis for chemotactic specificity in h

ISSN:0022-104X    

DOI:10.1002/jez.1401820302

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

年代:1972

数据来源: WILEY

摘要:

AbstractFertilization inCampanularia flexuosais internal. In both freshly collected colonies and laboratory cultured colonies eggs may be removed from the gonangium still attached to the blastostyle as a single packet surrounded by epithelial cells. Packets from mature gonangia of freshly collected colonies contain spermatozoa although the eggs are immature. The spermatozoa remain inside the packet to await egg maturation. Packets from mature gonangia of laboratory cultured colonies do not contain spermatozoa if male and female colonies are cultured separately. Eggs in such packets may be fertilized by the addition of spermatozoa. Removal of the epithelial cells which surround the eggs in the egg packet results in loss of fertilizability. Treatment of the egg packets with 0.75% trypsin also results in a loss of fertilizability. However, fertilizability may be restored by exposure of spermatozoa to non‐trypsin treated female epithelial cells. Thus, apparently a definite interaction must occur between female epithelial cells and spermatozoa prior to fertilization. This interaction may be analogous to mammalian capacitation and the necessary conditioning of amphibian sperm prior to fertilizatio

ISSN:0022-104X    

DOI:10.1002/jez.1401820303

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

年代:1972

数据来源: WILEY

摘要:

AbstractWater uptake in the crab,Rhithropanopeus harrisi, was studied using D2O (deuterium oxide) as a label. Results were expressed as per cent saturation, or the D2O concentration in the blood, attained in a 30‐minute exposure to D2O at 20°C, expressed as a percentage of the D2O concentration in the bathing medium. Crabs acclimated to 75% sea water (SW), to which the blood is about isosmotic, had a mean per cent saturation of 51.8, and in 10% SW‐acclimated crabs (blood hyperosmotic by about 40% SW) the mean per cent saturation was 33.9. Thus, water uptake, or exchange, is slower when the osmotic gradient favors net water uptake than when no osmotic gradient exists. In gill chamber perfusion experiments at least 87% of the total water influx in 10% SW and 92% of the total in 75% SW are taken up in the gill chambers, the gills probably being responsible for most, if not all, of the uptake. The time course of acclimation between 10% SW and 75% SW was followed in both directions. Measurable changes in water uptake occurred in 30 minutes; half the change from 75% SW to 10% SW occurred in two hours (seven hours for the transfer from 10% SW to 75% SW), and over 90% of full acclimation was reached in two days.Gill chamber perfusion experiments showed that the receptor or receptors which perceive the change between 10% and 75% SW and mediate the change in water uptake are not in the gill chamber. Thus the system responsible for the change in water uptake is composed of at least a receptor with some means of communication (presumably nervous or hormonal) with the effectors (probably the gills).The use of Na+‐free and Cl−‐free D2O media showed that the absence of these ions did not affect water uptake, and that the change in water uptake was not caused by a change in influx of

ISSN:0022-104X    

DOI:10.1002/jez.1401820304

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

年代:1972

数据来源: WILEY

摘要:

AbstractInvestigations, employing the drug cytochalasin B (CB), have been carried out in an effort to determine the mechanisms underlying the processes involved in polar body formation and their possible relation to cytokinesis of mitosis. Fertilized eggs of the surf clam,Spisulawere treated with 1 or 10 μg/ml CB and prepared for light and electron microscopy. Germinal vesicle breakdown and formation of the first meiotic spindle are similar in CB treated zygotes and in controls. At anaphase I a cytoplasmic protrusion develops at the site of the peripheral aster and contains dyad chromosomes. Although the inner aspect of the plasma membrane of this projection in CB treated zygotes is lined with a discontinuous layer of fine textured material, a cleavage furrow fails to form and the cytoplasmic bleb gradually regresses in size. The failure of the presumptive first polar body to cleave results in the presence of two groups of dyads within the zygote. These become aligned on separate or shared meiotic spindles in preparation for the second meiotic division. At anaphase II a protrusion, structurally similar to the first, is formed which also fails to separate from the zygote via a cleavage furrow. Due to the absence of polar body formation, four groups of maternally derived chromatin may be observed at the animal hemisphere of the zygote. These groups are organized into female pronuclei (usually 4) which may not be of equal ploidy. Failure of the cleavage furrow to develop during polar body formation in CB treated zygotes suggests that the filamentous material associated with the leading edge of the furrow of control specimens may function in a manner proposed for the contractile ring of mitotic cells

ISSN:0022-104X    

DOI:10.1002/jez.1401820305

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

年代:1972

数据来源: WILEY

摘要:

AbstractDevelopmental stages, from eight cells to 28 days post‐hatching, of the zebrafish,Brachydanio rerio, were analysed by immunoelectrophoresis with unabsorbed and absorbed rabbit antiserum to adult zebrafish brain. From the earliest embryonic stage to the oldest post‐hatching stage tested, a developing antigenic pattern was recognizable. Six antigens, found to be consistently present in all stages, exhibited no observable variation in electrophoretic mobility or diffusion rates. Of four other antigens present in the earliest stage analysed, one appeared intermittently throughout subsequent developmental stages. Three antigens appeared consistently, but showed variations in electrophoretic mobility at different stages. Fourteen ‐antigens, two of which were transitory, appeared during development, adding to the complexity of the antigenic pattern. Including all stable and variant forms of antigens, a total of 30 antigens was detected from the earliest embryonic stage to the oldest post‐hatching stage

ISSN:0022-104X    

DOI:10.1002/jez.1401820306

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

年代:1972

数据来源: WILEY

摘要:

AbstractToads of the speciesXenopus laeviswere immersed in 5 mM NH4Cl or 5 mM NaCl for periods of up to 28 days. In stronger solutions of NH4Cl, toads died within one hour. The rate of excretion of ammonia and urea and the activities of carbamyl phosphate synthetase, ornithine transcarbamylase, arginase and glutamate dehydrogenase in liver and kidney were measured. In toads in 5 mM NH4Cl, the excretion of urea was increased about ten‐fold, and there were increases in the activities of carbamyl phosphate synthetase and glutamate dehydrogenase in the liver. The activities of ornithine transcarbamylase and arginase in the liver, and of glutamate dehydrogenase in the kidney, were unaffected. In toads in 5 mM NaCl, there was no change in the rate of urea excretion or in the activities of any of the enzymes assayed. It was concluded that a rise in tissue ammonia levels is followed by alterations in the metabolic pathways of the toads which result in a decrease in those levels. Thus, the transition to ureotelism inX. laevisis triggered by an increase in tissue ammonia levels. Because there was no response to immersion in 5 mM NaCl, it is concluded that a slight increase in the osmotic pressure of the external medium has no effect, and that urea is of little significance in osmotic regulation in this toa

ISSN:0022-104X    

DOI:10.1002/jez.1401820307

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe identity and site of synthesis of the yolk proteins of the mosquitoAedes aegyptiwere studied. Disc gel electrophoresis of freshly prepared egg yolk revealed a predominant protein (YP‐1) which stained for bound lipid and carbohydrate. The molecular weight of the protein complex was estimated to be 2.7 × 105. It was present in vitellogenic females and absent in males and unfed females.Yolk Protein‐1 was purified by Sepharose and DEAE column chromatography and represented 75% of the protein extractable from the egg. The lipids conjugated to YP‐1 were identified as phosphatidyl choline, phosphatidyl ethanolamine and several steroids. The carbohydrate content was estimated as 10.5% with a phenol‐sulfuric acid method, and 5.8% with an orcinol method.The site of yolk protein synthesis was determined using antibody to purified yolk to precipitate labeled yolk proteins from organ culture media. Only the fat body synthesized antibody precipitable material. Synthesis began five to six hours after the blood meal, reached a peak of activity by 20 hours and declined to low levels of synthesis by 72 hours. These data correlate well with endocrino‐logical evidence indicating that egg development requires a hormonal factor from the head from four to eight hours after the

ISSN:0022-104X    

DOI:10.1002/jez.1401820308

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

年代:1972

数据来源: WILEY

摘要:

AbstractThere is active uptake of radioactive nickel by fertilized eggs and embryos of the sea urchinLytechinus pictus.The nickel taken into the cells is free and can be released by the addition of exogenous, non‐radioactive nickel. The morphological development of embryos raised in sea water containing 10−2to 10−6MNiCl2was investigated. Nickel uptake is initiated right after fertilization, but its effect on development does not appear until much later. Embryos grown in 10−2and 10−3MNiCl2cleaved at a normal rate and formed blastulae but did not gastrulate. Embryos grown in 10−4to 10−6MNiCl2were able to gastrulate but failed to develop dorsoventral symmetry and formed radi

ISSN:0022-104X    

DOI:10.1002/jez.1401820309

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

年代:1972

数据来源: WILEY

摘要:

AbstractAnnual fishes can maintain permanent populations in temporary aquatic habitats since the population survives dry seasons in the form of diapausing eggs. Populations persist even though subject to erratic environmental cycles and recurrent ecological catastrophes.Developmental arrest occurs at one or all of the following stages: Diapause I (Dispersed cell phase); Diapause II (Long somite embryo); Diapause III (Prehatching). InAustrofundulus, Diapause I is facultative. Diapause II and III are obligate, long and variable (105 ± 20 days each). Subpopulations (about 10%) of “escape eggs” bypass Diapause II and/or Diapause III.PterolebiasandRachoviaeggs behave much like those ofAustrofundulus. InRachovia, the duration of Diapause II is 80 ± 33 days and of Diapause III at least 61 ± 23 days. Subpopulations of “escape eggs” are present.CynolebiasandNothobranchiuscan undergo facultative arrest at Diapause I and II and enter obligate arrest at Diapause III. Annual species ofAphyosemioncan undergo facultative arrest at Diapause I and II, and an obligate arrest at Diapause III. A few species may also experience obligate arrest at Diapause II. A short term arrest phenomenon, “retarded hatching,” sometimes is encountered among non‐annualAphyosemionsand other non‐annual cyprinodonts.Survival strategy is based on the “multiplier effect”; i.e., interposition into the developmental pathway ofthreebranch points containing diapause stages of prolonged, variable duration generateseightdifferent distributions of total developmental time. Thus, a single egg population of identical age can generate several subpopulations, all of which develop according to different schedules. A developmental program is established which permits the repeated loss of individual eggs under conditions which may initiate hatching but do not allow for maturation and successful reproduction. The “multiplier effect” augmented by other adaptations guarantees that some portion of the egg population

ISSN:0022-104X    

DOI:10.1002/jez.1401820310

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

年代:1972

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1401820301

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

年代:1972

数据来源: WILEY