摘要:

AbstractAlthoughNotoplana acticola, a marine polyclad, cannot regenerate brain tissue, neuronal repair is rapid. Brains were transplanted into decerebrate flatworms to determine the anatomical patterns and functionality of neural connections established between a new brain and the peripheral nerve network of the recipient animal. Sixty‐nine transplants were performed. Four brain transplant orientations were used: normal, reversed, inverted, and reversed inverted. The functionality of the transplanted brains was tested and measured using both behavioral and electrophysiological criteria. Within 23 days, 56% of the transplants that survived and retained the transplants recovered the four behaviors tested: righting behavior, avoidance turning, ditaxic locomotion, and feeding. Nerves exiting the brain tended to join with the peripheral nerves closest to them. Anatomical connections were made within 24 hr of surgery. Some normal behavior was seen within the first 36 hrs after surgery. Control decerebrate worms did not recover behavior. Preliminary intracellular recordings from three types of identified brain sensory interneurons, in transplants, revealed normal electrophysiological properties and this implied that appropriate connections with peripheral sensory cells had been reestablished. Intracellular dye‐marking of these neurons in reverse‐oriented brains revealed that, although individual nerve processes apparently leave the brain and associate with inappropriate nerve cords, some of the processes turn 180° to reinervate nerve cords, which they normally occupy in unoperated animals. Thus, although anatomical and functional neural connections apparently were made rapidly following brain transplantation, the specificity of the reconnections remains to be

ISSN:0022-104X    

DOI:10.1002/jez.1402350202

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe in vitro biological actions of synthetic chum salmon melanin concentrating hormone (MCH) on melanophores of the blue damselfish (a teleost),Chrysiptera cyanea, were studied. This cyclic heptadecapeptide stimulated melanosome (melanin granule) aggregation (centripetal migration) within melanophores at a threshold concentration of about 10−10M. The action of this putative hormone was not blocked by α‐ or β‐adrenoceptor antagonists. It was concluded that the effects of MCH were direct and were not mediated indirectly through the actions of adrenergic neurotransmitters released from nerve terminals. Further evidence for this view comes from the observation that, unlike the case of neurotransmitter release, melanosome aggregation in response to MCH proceeded in the absence of calcium. The possible role of MCH in the control of color change of teleost fishes is di

ISSN:0022-104X    

DOI:10.1002/jez.1402350203

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe isomeric configuration of the 3,4‐didehydroretinal chromophore of goldfish porphyropsin was determined by high performance liquid chromatography (HPLC) and by the regeneration of this visual pigment with authentic isomers of 3,4‐didehydroretinal. A nonisomerizing, quantitative method using hydroxylamine and methylene chloride was employed to extract the 3,4‐didehyroretinal chromophore from the rod outer segment membrane (containing the porphyropsin). When this extracted chromophore was injected into the HPLC, only a single major peak was observed and this peak coeluted with the authentic 11‐cis3,4‐didehydroretinyl oxime. This suggests that the chromophore of goldfish porphyropsin is 11‐cis3,4‐didehydroretinal. When the bleached rod outer segments (containing the opsin) were incubated with different 3,4‐didehydroretinal isomers (13‐cis, 11‐cis, 9‐cis, and all‐trans), only the 11‐cisisomer resulted in the degeneration of porphyropsin. This also suggests that the porphyropsin chromophore exists i

ISSN:0022-104X    

DOI:10.1002/jez.1402350204

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe development of a highly specific radioimmunoassay for salmonid prolactin (PRL) using chinook salmon PRL allowed us to study plasma and pituitary PRL profiles in large sedentary rainbow trout (Salmo gairdneri) transferred from fresh water to seawater and vice versa. Plasma osmotic pressure and chloride levels were also measured for 3 weeks following change of salinity. Within 1 day after transfer to full seawater we observed a plasma PRL decrease, which stayed significantly lower (3–5 ng/ml) than the fresh water control group (10–15 ng/ml) during the entire experiment. Pituitary PRL content showed an initial abrupt increase, but after 3 weeks in seawater pituitary PRL content had decreased to the same level as in the fresh water control group. On the contrary, transfer from seawater to fresh water was followed within 1 day by a rise in plasma PRL levels, which stayed high (10–15 ng/ml) after 3 weeks in fresh water. Simultaneously, pituitary PRL content decreased significantly. These results may indicate an important role of PRL in fresh water adaptation of sedentary rainbow

ISSN:0022-104X    

DOI:10.1002/jez.1402350205

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

年代:1985

数据来源: WILEY

摘要:

AbstractTwo types of electrical potentials were recorded from competent echinopluteus larvae ofLytechinus pictus. The first was associated with reversal of cilia that line the ridges of larval epaulettes. Ciliary reversal potentials were recorded from all parts of the larvae and from isolated body parts. Estimated conduction velocity of ciliary reversal potentials was 10–20 cm/s. The second type of potential was largest when the electrode was placed over the urchin rudiment. Rudiment potentials could not be recorded from isolated epaulettes and could not be correlated with any obvious behavior of the larva.Both potentials increased in frequency when a larva was brought in contact with a “conditioned” substrate. Ciliary reversal potential frequency increased six‐ to seven fold within a minute or two of contact and remained elevated until the point of partial tissue collapse during metamorphosis. Rudiment potential frequency also increased, but only three‐ to five fold and with a longer latency (3–6 min to peak frequency). Rudiment potentials maintained an elevated level of firing through total tissue collapse, at which time the larvae were electrically silent. Attempts to record from juvenile urchins, to determine the fate of the rudiment potential system in the final stage of metamorphosis, were u

ISSN:0022-104X    

DOI:10.1002/jez.1402350206

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

年代:1985

数据来源: WILEY

摘要:

AbstractElectron microscopy and indirect immunofluorescence were employed to correlate the distribution patterns of major contractile proteins (actin and myosin) with 1) the organizational state of microfilaments, 2) the apical cell surface topography, 3) the shape of the neuroepithelial cells, and 4) the degree of bending of the neuroepithelium during neurulation in chick embryos at Hamburger and Hamilton stages 5–10 of development. Both actin and myosin are present at these developmental stages and colocalize in the neural plate as well as in later phases of neurulation. During elevation of neural folds, actin‐ and myosin‐specific fluorescence is always most intense in regions where the greatest degree of bending of the neuroepithelium takes place [e.g., the midline of the V‐shaped neuroepithelium (early neural fold stage) and the midlateral walls of the “C”‐shaped neuroepithelium (mid–neural‐fold stage)]. This intense fluorescence coincides with 1) a particularly dense packing of microfilaments and 2) highly constricted cell apices. After neural folds make contact, there is an overall reduction in both the intensity of apical fluorescence and the thickness of apical microfilament bundles, especially in the roof and floor of the neural tube. The remaining fluorescence in the contact area is apparently related to cellular movements during fusio

ISSN:0022-104X    

DOI:10.1002/jez.1402350207

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe purpose of this investigation was to explore the capacity of isolated asters of the mitotic apparatus of elicit contractile activity in adjacent cell surface. When a fertilizedEchinarachnius parmaegg with an intact mitotic apparatus was confined in an 82‐μm‐i.d. silicone rubber capillary, the furrow developed at the midpoint between the asters. The mitotic apparatus could be broken by inserting and ejecting the egg from the capillary. The asters of a broken mitotic apparatus were usually abnormally far apart. When asters were as far as 68 μm apart, furrowing occurred; when the intervening distance was greater, there was no furrowing. When the asters were too far apart to establish a furrow between them, constrictions appeared adjacent to one of the asters. The constrictions could shift or could cut through the asters that appeared to elicit them. Cylindrical cells in 0.015 M ethyl urethane formed furrows when the mitotic apparatus was intact but formed neither furrows nor astral constrictions when the asters were far apart. Astral constrictions did not form in the presence of an active furrow. They were frequently temporary and they appeared to be slower and less acute than normal furrows. Single asters remaining after half of the amphiaster was removed had the same effect as widely separated asters. The form of the constriction was related to the position of the aster in the cylinder. When the aster was centered, the constriction resembled a furrow; but when it was near one of the poles, the adjacent surface pulled away from the capillary wall and the radius of curvature at the pole decreased. When initially distant asters were pushed together, a furrow formed between them. These results contribute to a better understanding of the interaction between the mitotic apparatus and the egg surface and the formation of the cleavage mech

ISSN:0022-104X    

DOI:10.1002/jez.1402350208

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

年代:1985

数据来源: WILEY

摘要:

AbstractInXenopus laevisembryos a high concentration of both KCl and 0.5% DOC (sodium deoxycholate) is needed for maximal extraction of ribosomes and polysomes. We studied the nature of the structures that keep ribosomes and polysomes immobilized within the cytoplasm of embryonic cells at cleavage through tailbud stages, using various combinations of a low‐salt buffer (20 mM KCl), a high‐salt buffer (500 mM KCl), 0.5% DOC, and 0.5% Triton X‐100. With a low‐salt buffer and 0.5% DOC, but not Triton X‐100, 80S ribosomal monomers and polysomes were liberated from the cytoplasmic rapidly sedimenting structures (RSS) to the soluble fraction. With a high‐salt buffer (500 mM KCl), ribosomes were solubilized as 60S and 40S subunits together with about one‐half of the total polysomes. When cells were homogenized in a low‐salt buffer with added inhibitors of the cytoskeleton (cytochalasin B or colchicine), the majority of polysomes but not ribosomes were solubilized. These results provide evidence for the following conclusions. 1) Polysomes are bound to cytoskeletal structures inXenopusembryos, but ribosomes, both maternal and newly synthesized, are associated with membranous noncytoskeletal structures. 2) The membranous structures consist of two compartments, one high‐salt sensitive and the other high‐salt resistant. 3) Ribosomes of the high‐salt resistant group increase in amount with developmental stage and appear to be the precursor to the ribosomes of the high

ISSN:0022-104X    

DOI:10.1002/jez.1402350209

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

年代:1985

数据来源: WILEY

摘要:

AbstractThree albino mutants of the fowl were tested for tyrosinase activity. Two of these mutants (candca) are alleles at the autosomalClocus, while the third mutant (sal) is sex‐linked. Both the standard type,E, andsalare tyrosinase positive whereas the twoCmutants are tyrosinase negative. Anti‐chicken tyrosinase mouse serum was produced and all four genotypes were found to have cross‐reacting material to this antiserum. Tyrosinase from the standard type was isolated and its location on denaturing two‐dimensional gels determined. A co‐migrating series of spots was found within the protein pattern of both the standard type and the tyrosinase positive albino,sal. The same pattern of spots was also observed forcandcawith no apparent change in either the pI or the molecular weight. Transmembrane blots also showed spots that reacted with anti‐tyrosinase serum in all four genotypes and that migrated to the same location as that of standard tyrosinase. It is proposed that bothcandcaare CRM+mutants which produce tyrosinase‐like molecules that are inactive due to a change that is electrophoretically and antigenic

ISSN:0022-104X    

DOI:10.1002/jez.1402350210

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

年代:1985

数据来源: WILEY

摘要:

AbstractCyclic guanosine 3′,5′‐monophosphate (cGMP) was injected into fertilized starfish eggs in order to study the effects of this cyclic nucleotide on early embryogenesis. cGMP at approximate intracellular concentrations higher than 0.05 mM causes achromosomal cleavage in the presence of 1 mM caffeine, that is, each blastomere is devoid of a nucleus but not spindle and asters. The treated embryos cleave slower than control, never form blastulae, and disintegrate just before blastulation. cAMP, dibutyryl cGMP and dibutyryl cAMP failed to cause achromosomal cleavage. These results suggest that unphysiologically high levels of intracellular cGMP inhibit in vivo DNA synthesis of fertilized starfish

ISSN:0022-104X    

DOI:10.1002/jez.1402350211

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

年代:1985

数据来源: WILEY