摘要:

AbstractA new procedure is presented for the isolation of electron microscopically clean melanosomes. The procedure provides melanosomes which have been stripped of their membrane components so that only matrix elements are examined. Solubilization of these melanosomes is by 8 M urea‐1% Triton X‐100 treatment with reduction and alkylation. The proteins are examined on sodium dodecyl sulfate‐polyacrylamide gels and on acid‐urea polyacrylamide gels. Evidence is presented indicating the presence of four low‐molecular‐weight proteins which have not previously been reported. Data indicate that these proteins are the major components of the melanosome matrix, that they are not histones and that at least one of them is a g

ISSN:0022-104X    

DOI:10.1002/jez.1402190102

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe cytosolic malate dehydrogenase (s‐MDH) from larval brine shrimp has been immunochemically characterized by quantitative rocket immunoelectrophoresis (IEP) and antibody catalytic inhibition studies. Monospecific rabbit antiserum produced against purified naupliar s‐MDH was used for rocket IEP as a quantitative assay for the cytoplasmic isozyme. Since cross‐reactivity was not observed against the mitochondrial MDH (m‐MDH), the assay allows specific measurement of the s‐MDH in crude naupliar supernatants in the presence of contaminating m‐MDH. The assay has a sensitivity of approximately 100 nanograms s‐MDH protein using either purified enzyme solutions or crude supernatant preparations. Catalytic inhibition studies using the monospecific antiserum gave 85% inhibition of s‐MDH but did not give significant inhibition of the m‐MDH. Lack of complete s‐MDH inhibition by the antiserum suggests a difference between the enzyme active site and immunological binding site. Although the antiserum was produced against s‐MDH from nauplii of the San Francisco Bay population, the antiserum inhibits equally well the s‐MDH of Great Salt Lake (Utah) nauplii, indicating little if any structural difference in the immunological sites of the s‐MDHs from these two geographical sources. Porcine (s‐ and m‐MDH), bovine (m‐MDH), and pigeon (m‐MDH) were also tried as antigens against the brine shrimp s‐MDH antiserum, but antigen‐antibody reactivity was not observed during rocket IE

ISSN:0022-104X    

DOI:10.1002/jez.1402190103

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

年代:1982

数据来源: WILEY

摘要:

AbstractBrine shrimp nauplii challenged with artificial sea water containing 2.5 M NaCl maintain significantly higher levels of cytoplasmic malate dehydrogenase (s‐MDH) than larvae incubated in sea water having 0.5 M NaCl. Eight to ten hours after emergence, free‐swimming nauplii living in 0.5 M NaCl exhibit a steady decline of s‐MDH for 20–40 hours; the decrease is less and stabilizes earlier — in nauplii incubated in 2.5 M NaCl. The14C‐labeled amino acids produced by H14CO3fixation were rapidly incorporated into newly formed s‐MDH protein as assayed using quantitative rocket immunoelectrophoresis (IEP) with monospecific antiserum prepared against purified brine shrimp s‐MDH. Higher rates of enzyme biosynthesis (>45%) occurred in 2.5 M NaCl together with rapid s‐MDH turnover (half‐life = 17 hours), accounting for the difference observed in enzyme level between different salt regimes. In contrast, incorporation of14C‐labeled amino acids into total cytoplasmic protein decreases slightly in high salt, suggesting that a preferential synthesis of s‐MDH is taking place. Temporal patterns of s‐MDH during embryonic development were monitored using both catalytic activity and quantitative IEP assays. Levels of s‐MDH seen in encysted gastrulae (0.22 units or 0.57μg s‐MDH protein/100 embryos) remain relatively constant through the E1and E2emergent stages until the exhibited decline observed in the naupliar stage. The results are discussed in relation to the bioenergetics and temporal development of water and ele

ISSN:0022-104X    

DOI:10.1002/jez.1402190104

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

年代:1982

数据来源: WILEY

摘要:

AbstractGoldfish (Carassius auratus) were subjected to both long‐ and short‐term (1, 3, 6, and 170 days) constant light or constant darkness to determine the effects of environmental lighting on the morphology of photoreceptor cells in the pineal organ. Morphometric analysis of electron micrographs from each experimental group suggested that the effects of constant darkness are morphologically expressed only after long‐term (6 months) exposure. These included an increase in the volume of photoreceptor and phagocytic cells, area of rough endoplasmic reticulum, and volume of mitochondria per photoreceptor cell, and a decrease in the size of individual Golgi bodies. On the other hand, the response to constant light occurred generally within the first 6 days. Under these conditions, there was a reduction in outer‐segment volume, but an increase in both the volume of Golgi per photoreceptor cell and size of individual Golgi bodies. Synaptic ribbons in these specimens were longer at every time sampled. The results of this study provide evidence that photoreceptor cell organelles involved in synthesis and secretion, as well as photosensory functions, are influenced by environmental l

ISSN:0022-104X    

DOI:10.1002/jez.1402190105

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

年代:1982

数据来源: WILEY

摘要:

Abstract(1)Aplysia californicaexhibit a diurnal circadian locomotr rhythm (Strumwasser, '67). The rhythm appears to be timed by circadian pacemakers located within the eye, although extraocular photoreceptors and pacemakers also influence locomotor behavior (Strumwasser, '73; Lickey et al., '77). (2) The present study was undertaken in an attempt to identify the pathways ganglia, which are responsible for generatating locomotor movements. A lesion study was performed in which either of the two pairs of bilaterally symmetrical cerebral connectives were cut and the effect on locomotor behavior evaluated. (3) The results indicate that the cerebro‐pleural connectives are not involved in control of locomotor acitivity (Fig. 2). On the other hand, the cerebro‐pedal connectives are critical for ocular and extraocular control of locomotor thythmicity (Figs. 3,4). Animals with bilateral cerebropedal lesions are arrhythmic on light cycles. (4) Multiunit recording in vivo and in vitro revealed the presence of a descending signal in the cerebropedal connective upon the application of a light pulse to the animal. Further experimentation localized the origin of these signals to the tentacles, rhinophores and eyes (Figs. 6, 7). (5) We conclude that the elements comprising the circadian system ofAplysiaare located in a restricted portion of the central nervous system including the cerebral and buccal ganglia, and sensory structures served by cerebral or buccal ner

ISSN:0022-104X    

DOI:10.1002/jez.1402190106

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn embryos of the gastropod,Ilyanassa obsoleta, ribosomal RNA (rRNA) synthesis first becomes detectable using sucrose gradients at the end of cleavage (by 24 hours post trefoil at 19°C; the trefoil stage is characterized by maximal extension of the third polar lobe, in association with first cleavage). The nuclei of early embryos, however, contain several prominent nucleolus‐like bodies (NLBs) from the 2‐cell stage onward. Investigation of these NLBs ultra‐structurally and cytochemically has led to a model for nucleologenesis and the regulation of expression of the rRNA cistrons during cleavage. Throughout the cleavage period, NLBs consist of homogeneous, spherical accumulations of 5–8 nm diameter fibrils. By 18 hours post trefoil, they have become extensively associated with chromatin. By 22 hours post trefoil there are definitive, chromatin associated nucleoli which have a distinct, 15–25 nm granular component surrounding and intermingling with a matrix of 5–8 nm fibrils. This period marks the beginning of a reduction in the number of NLBs per nucleus, until most post‐gastrula nuclei contain only one or two definitive nucleoli. Both NLBs and nucleoli stained selectively with bismuth, which Locke and Huie ('77) consider to be specific for basic proteins within the nucleolus. In contrast, a silver staining technique (Bloom and Goodpasture, '76) selective for active nucleolus organizers stained nucleoli of post‐gastrula embryos but not NLBs of mid‐cleavage embryos. Electron microscope autoradiography showed the incorporation of3H‐uridine into NLBs beginning in late cleavage, just prior to the appearance of a granular nucleolar component. The agranular NLBs present in cleavage nuclei appear, therefore, to be precursors of the fibrillar matrix of the nucleoli which eventually replace them. This transition is coincident with the activation of rRNA gene expression as NLBs associate with chromatin towards

ISSN:0022-104X    

DOI:10.1002/jez.1402190107

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

年代:1982

数据来源: WILEY

摘要:

AbstractA procedure is described for the mechanical dissociation and culturing of early stage newt regenerate blastema cells. The specified growth medium is adjusted to suitable osmolarity and consists of Leibovitz L‐15, water, fetal calf serum, and insulin. This provides a suitable environment in which growth, proliferation, and some differentiation occur with time as evidenced by phase contrast photographs of living culture

ISSN:0022-104X    

DOI:10.1002/jez.1402190108

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe behavior of epidermal cells was studied by employing two in vitro systems in which reepithelialization occurs: the single explant system and the fused system. Single explants (4–5 mm2) are prepared from the tailfins ofR. catesbeianatadpoles and cultured in Hank's balanced salt solution at 22°C. The fused system is prepared by placing single tailfin pieces on either side of a tailfin piece that was stripped of its epidermis. These tissues are placed onto a Millipore filter and cultured in Hank's at 22°C. In these experiments one can study the effect of the substrate, core vs a collagenous basement membrane, on the behavior of epidermal cells during reepithelialization.The results of these experiments demonstrate that there are differences in the behavior of epidermal cells in these two systems. In the fused system wound closure is associated with the occurrence of “contact inhibition,” the cessation of further cell migration, and the presence of an epidermal layer that exhibits a normal cytoarchitecture in the wound area. However, in the single explant system, wound closure occurs but an overaccumulation of epidermal cells in the wound area, “capping,”

ISSN:0022-104X    

DOI:10.1002/jez.1402190109

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis investigation was designed to test the hypothesis that there is a direct relationship between quantity of innervation and regenerative capacity. This was done by measuring the quantity of innervation in 13 different species of amphibians chosen to represent a spectrum of regenerative abilities. When looking at the five urodele species alone, or when comparing urodeles and eight anuran species, the results show a lack of correlation between regenerative capacity and quantity of innervation. However, if the anurans alone are considered, the four species in which regeneration has been observed all have levels of innervation greater than in the four species that do not regenerate. This suggests the possibility that an adequate quantity of innervation may be a limiting factor for limb regeneration in anurans, but is not a limiting factor in urodeles.

ISSN:0022-104X    

DOI:10.1002/jez.1402190110

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe sperm of the toad,Bufo bufo japonicus, smeared on a gelatin film displays a “halo” reaction around the acrosomal region. The treatment of sperm with 0.5% Triton X‐100 yielded activity which lyses the vitelline coat (VC) of coelomic eggs, but not the fertilization coat of activated eggs. Electronmicroscopy showed that these detergent‐treated sperm had lost the plasma membrane and the acrosomal cap, indicating acrosomal localization of the VC lysin. The VC lysin was able to lyse the VCs of several heterologous anuran species, and this activity correlated well with the occurrence of cross‐fertilization byBufosperm. Proteolytic activities of the VC lysin were quantitated employing N,N‐dimethylated VC proteins or casein as substrates. Successive fractionation by NH42SO4precipitation, DEAE‐cellulose chromatography, and Sephadex gel filtration yielded a 100‐fold increase of proteolytic activity compared with that of the original detergent extract. On gel filtration, the VC lysin activity was recovered both in the M.W. 54,000 fractions and the considerably higher (>100,000) M. W. fractions. Part of the latter activity was recoverable in the former after the treatment with urea and rechromatography. The VC lysin was most active at pH 7.4, but its activity was lost by preincubation at temperatures higher than 60°C. The activity was inhibited considerably by serine‐protease and chymotrypsin inhibitors, but not at all by trypsin inhibitors. The lysin was unable to hydrolyze arginine or tyrosine esters, but was able to hydrolyze active site titrants for chymotrypsin more effectively than for trypsin. In all aspects the VC lysin, although sharing some properties with serine‐proteases such as chymotrypsin, is a unique proteinase(s) well adapted to its r

ISSN:0022-104X    

DOI:10.1002/jez.1402190111

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

年代:1982

数据来源: WILEY