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1.
Fifty-seven species of hermatypic corals have been maintained and grown in high-nutrient seawater at the Waikiki Aquarium, Honolulu, Hawaii. In this study we document the chemical conditions of aquarium water in terms of dissolved nutrients and carbon. Aquarium water is characterized by concentrations of inorganic nutrients that are high relative to most natural reef ecosystems: SiO3 200 M; PO4 0.6 M; NO3 5 M; NH4 2 M. In contrast, concentrations of organic nutrients are lower than most tropical surface ocean waters: DOP 0.1 M and DON 4 M. The incoming well-water servicing the facility has low pH, crating over-saturation of carbon dioxide. The coral communities in aquaria took up inorganic nutrients and released organic nutrients. Rates of nutrient uptake into aquaria coral communities were similar to nutrient uptake by natural reef communities. Coral growth rates were near the upper rates reported from the field, demonstrating corals can and do flourish in relatively high-nutrient water. The growth of corals does not appear to be inhibited at concentrations of nitrogen up to 5 M. Statements implying that corals can only grow in low nutrient oligotrophic seawater are therefore oversimplifications of processes that govern growth of these organisms. Some basic guidelines are given for maintenance of coral communities in aquaria.  相似文献   

2.
Summary The purpose of the present study was to analyse quantitatively the localization of calmodulin antagonist, n-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7) in CHO-Kl cells. The cultured CHO-Kl cells were labelled with 1 (16.7 M), 2 (33.4 M), 5 (83.5 M) and 10 Ci/ml (167 M) tritiated W-7. Some cells were preincubated in 10, 50 and 100 M unlabelled W-7 for 30 min and then labelled with 2 or 5 Ci/ml tritiated W-7 for 1 h. The cells were doubly fixed in glutaraldehyde and osmium-tetroxide solution, and embedded in Epon. For light-microscopic radioautography, 2 m-thick sections were wet mounted with radioautographic emulsion and exposed for 1 month. The radioautograms showed that large numbers of silver grains were mainly localized in the cytoplasm as well as in the nucleus. Quantitative analysis demonstrated that, in both the cytoplasm and nucleus, the number of silver grains was dependent on the concentration of the administered tritiated W-7 and the number was dramatically decreased by the pretreatment of unlabelled W-7. These results show that, in CHO-Kl cells, the W-7 binding sites are saturable. It is concluded that W-7 may get into CHO-Kl cells and be bound to a specific protein that may be calmodulin protein.  相似文献   

3.
-glucanases are prominent proteins in pea endocarp tissue responding to fungal infection. We have cloned and sequenced a partial pea cDNA clone, pPIG312, corresponding to a -1,3-glucanase in pea pods challenged with the incompatible pathogen Fusarium solani f. sp. phaseoli. The insert from the partial pea cDNA was used to probe a genomic library derived from pea leaves of the same cultivar. One of the genomic clones, pPIG4-3, contained the complete coding sequence for a mature -1,3-glucanase protein. The predicted amino acid sequence of the pea -1,3-glucanase has 78% identity to bean -1,3-glucanase, 62% and 60% to two tobacco -1,3-glucanases, 57% to soybean -1,3-glucanase, 51% to barley -1,3-glucanase, and 48% to barley -1,3-1,4-glucanase. Genomic Southern analysis indicates that the pea genome contains only one -1,3-glucanase gene corresponding to the probe used in this study. Accumulation of -1,3-glucanase mRNA homologous with the pPIG312 probe was detected in pea pods within 4 to 8 h after challenge with F. solani f. sp. phaseoli, f. sp. pisi, a compatible strain, or the elicitor, chitosan. In the incompatible reaction, mRNA accumulation remained high for 48h, whereas it rapidly decreased in the compatible reaction. After fungal inoculation of whole pea seedlings, the enhanced mRNA accumulation occurred mainly in the basal region (lower stem and root). This -1,3-glucanase glucanase mRNA was constitutively expressed in the roots of pea seedlings. The sustained levels of -glucanase mRNA expression induced by the incompatible pathogen in the resistance response suggests that the enzyme contributes to the pea plant's general defense.  相似文献   

4.
Exchange-out of amide tritium from labeled -subunit of 33 complex of F0F1-ATP synthase was not accelerated by ATP, suggesting that hemagglutinin-type transition of coiled-coil structure did not occur in -subunit. Local topology of nucleotide binding site and switch II region of G-protein resemble those of F1- subunit and other proteins which catalyze ATP-triggered reactions. Probably, binding of nucleotide to F0F1-ATP synthase induces conformational change of the switch II-like region with transforming subunit structure from open to closed form and this transformation results in loss of hydrogen bonds with the subunit, thus enabling the subunit to move.  相似文献   

5.
Summary The seed storage proteins of maize (Zea mays L.) are synthesized during endosperm development on membrane-bound polyribosomes. These proteins, collectively called zeins, are translocated into the lumen of the rough endoplasmic reticulum, where they assemble into protein bodies. Protein body formation in normal genotypes occurs via an ordered deposition of the various types of zeins, and leads to the formation of spherical structures with a diameter of about 1 m. These structures consist of a central core that contains predominantly -zein; this central region is surrounded by a peripheral layer of - and -zeins, and the entire structure is bounded by rough endoplasmic reticulum.In the endosperm mutant floury-2 the levels of all classes of zeins are reduced; these kernels exhibit an opaque phenotype instead of the vitreous phenotype observed in normal genotypes. In contrast to the discrete, spherical protein bodies which are formed in normal maize endosperm, the protein bodies within floury-2 endosperm are irregular and the zeins are disorganized; patches of - and -zeins occur within irregularly lobed clusters of -zein within the lumen of the rough endoplasmic reticulum. The implications of this aberrant distribution are discussed, both with respect to protein body development and kernel characteristics.Abbreviations BSA bovine serum albumin - DAP days after pollination - IgG immunoglobulin G  相似文献   

6.
Summary The frequency of occurrence and the genetic structure of polylysogens were studied for phages , 80 and att80. In the case of , frequency of polylysogenization is high (0.20 to 0.41) with a tandem integration of prophages at the primary att site (att). With 80 and att80, this frequency is about 10 times lower, and usually one prophage becomes integrated at the primary att site (att80-I) while another (sometimes two others) integrates at one of the secondary sites. At least four secondary att80 sites have been found in wild-type Escherichia coli , two of which (near the his and tolC loci) are preferred. The frequency of secondary integration of 80 and att80 does not differ significantly in the wild-type host and in that deleted for the primary att site (0.041 and 0.045, respectively, among surviving cells at an MOI of 10).Homoimmune superinfection has revealed a constitutive cI-independent expression of the 80 int gene in the prophage state. The only 80 tandem detected proved to be unstable. With the 80int - mutant, we observed stabilization of 80 tandems; as a consequence, their frequency of occurrence during coinfection with 80int + was up to the level and no nontandem insertions were found. A model is proposed for the 80 and att80 nontandem integration.Abbreviations TP transducing phage(s) - PFU plaque-forming units - PC pink clear-resistant colonies on EMBO plates - MOI multiplicity of infection - O origin of Hfr transfer
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7.
Group A streptococcal M protein, a major virulence factor, is an alpha-helical coiled-coil dimer on the surface of the bacteria. Limited proteolysis of type 57 streptococcus with pepsin released two fragments of the M57 molecule, with apparent molecular weights of 32,000 and 27,000 on SDS-PAGE. However, on gel filtration under nondenaturing conditions, each of these proteins eluted as two distinct molecular forms. The two forms corresponded to their dimeric and monomeric state as compared to the gel filtration characteristics of known dimeric coiled-coil proteins. The results of sedimentation equilibrium measurements were consistent with this, but further indicated that the dimeric form consisted of a dimer in rapid equilibrium with its monomer, whereas the monomeric form does not dimerize. The monomeric form was the predominant species for the 27 kD species, whereas the dimeric form predominated for the 32 kD species. Sequence analysis revealed the 27 kD species to be a truncated derivative of the 32 kD PepM57 species, lacking the N-terminal nonheptad region of the M57 molecule. These data strongly suggested that the N-terminal nonheptad region of PepM57 is important in determining the molecular state of the molecule. Consistent with this, PepM49, another nephritis-associated serotype, which lacks the nonheptad N-terminal region, also eluted as a monomer on gel filtration under nondenaturing conditions. Furthermore, removal of the N-terminal nonheptad segment of the dimeric PepM6 protein converted it into a monomeric form. The dimeric molecular form of both the 32 kD PepM57 and the 27 kD PepM57 did not represent a stable state of assembly, and were susceptible to conversion to the corresponding monomeric molecular forms by simple treatments, such as lyophilization. The 27 kD PepM57 exhibited a greater propensity than the 32 kD species to exist in the monomeric form. The 32 kD species contained the opsonic epitope of the M57 molecule, whereas the 27 kD species lacked the same. This is consistent with the previous reports on the importance of the N-terminal region of M protein for its opsonic activity. Together, these results strongly suggest that, in addition to its importance for the biological function, the N-terminal region of the M protein plays a dominant role in determining the molecular state of the M molecule, as well as its stability.  相似文献   

8.
A systematic characterization of lens crystallins from five major classes of vertebrates was carried out by exclusion gel filtration, cation-exchange chromatography and N-terminal sequence determination. All crystallin fractions except that of -crystallin were found to be N-terminally blocked. -Crystallin is present in major classes of vertebrates except the bird, showing none, or decreased amounts, of this protein in chicken and duck lenses, respectively. N-Terminal sequence analysis of the purified -crystallin polypeptides showed extensive homology between different classes of vertebrates, supporting the close relatedness of this family of crystallin even from the evolutionarily distant species. Comparison of nucleotide sequences and their predicted amino acid sequences between -crystallins of carp and rat lenses and heat-shock proteins demonstrated partial sequence homology of the encoded polypeptides and striking homology at the gene level. The unexpected strong homology of complementary DNA (cDNA) lies in the regions coding for 40 N-terminal residues of carp -II, rat 2-1, and the middle segments of 23,000- and 70,000-M r heat-shock proteins. The optimal alignment of DNA sequences along these two segments shows about 50% homology. The percentage of protein sequence identity for the corresponding aligned segments is only 20%. The weak sequence homology at the protein level is also found between the invertebrate squid crystallin and rat -crystallin polypeptides. These results pointed to the possibility of unifying three major classes of vertebrate crystallins into one // superfamily and corroborated the previous supposition that the existing crystallins in the animal kingdom are probably mutually interrelated, sharing a common ancestry.  相似文献   

9.
The carbohydrate-binding specificity ofPseudomonas aeruginosa lectin I (PA-I) in iodinated or biotinylated form was studied. A large number of glycosphingolipids, as well as some glycoproteins and neoglycoproteins were used as ligands. Also, inhibition by free saccharides of PA-I binding to glycosphingolipids was tested. It was found that the lectin binds most strongly to terminal and nonsubstituted Gal3Gal- or Gal4Gal-structures.Abbreviations PA-I Pseudomonas aeruginosa lectin I - Cer ceramide - lactosylceramide Gal4GlcCer - iso globotriaosylcerami Gal3Gal4GlcCer - globotriaosylceramide Gal4Gal4GlcCer - globoside or globotetraosylceramide GalNAc3Gal4Gal4GlcCer - Forssman glycolipid GalNAc3GalNAc3Gal4Gal4GlcCer - P1 glycolipid Gal4Gal4GlcNAc3Gal4GlcCer - lactoneotetraosylceramide Gal4GlcNAc3Gal4GlcCer - B5 glycolipid Gal3Gal4GlcNAc3Gal4GlcCer - gangliotetraosylceramide Gal3GalNAc4Gal4GlcCer - GM1 Gal3GalNAc4(NeuAc3)Gal4GlcCer - RBC red blood cells - BSA bovine serum albumin - PBS phosphate-buffered saline - SDS sodium dodecyl sulfate - TLC thin-layer chromatography - HPLC high pressure liquid chromatography - MS mass spectrometry - FAB fast-atom bombardment - EI electron impact  相似文献   

10.
The purified isopropylmalate synthase of Alcaligenes eutrophus H 16 reacted with the following -keto acids and acyl-coenzyme A derivatives (in the sequence of decreasing affinities): -ketoisovalerate, -keto-n-valerate, -ketobutyrate and pyruvate; acetyl-CoA, propionyl-CoA, butyryl-CoA. malonyl-CoA, valeryl-CoA, and crotonyl-CoA. -Ketoisocaproate, however, is a strong inhibitor of the enzyme. All reactions catalyzed by isopropylmalate synthase were inhibited to the same extent by the endproduct l-leucine. the substrate saturation curves of -ketoisovalerate or other -keto acids and of acetyl-coenzyme A or other acyl-CoA derivatives had intermediary plateau regions; the Hill coefficient alternated between n H -values higher and lower than 1.0, indicating changes from positive to negative and from negative to positive cooperativity for the substrates. The products, isopropylmalate and free coenzyme A, showed competitive inhibition patterns against both substrates (-ketoisovalerate and acetyl-CoA). Free coenzyme A (1 M) inactivated the enzyme irreversibly. The 3-phosphate of coenzyme A and the free carboxyl group of -ketoisovalerate were involved in optimal binding of these substrates, but 3-dephospho-acetyl-coenzyme A and the methylester of -ketoisovalerate were also converted by this enzyme. A CH3–CH2-grouping of the -keto acids seemed to be necessary for binding this substrate.Abbreviations Used CoA Coenzyme A - Tris Tris(hydroxymethyl)aminomethane hydrochloride - DTNB 5,5-dithiobis-(2-nitrobenzoic acid) - IPM -Isopropylmalate - KIV -Ketoisovalerate Prepared from doctoral thesis of the University of Göttingen 1973  相似文献   

11.
The taxonomic significance of the trunk limbs of the chydoridae (Cladocera)   总被引:1,自引:1,他引:0  
N. N. Smirnov 《Hydrobiologia》1966,27(3-4):337-343
Summary The differences in the structure of the trunk limbs allow to outline three sections of Chydoridae (see table I and fig. 1), coinciding with the sections distinguished according to the structure of the head pores.
Chydoridae (Cladocera)
Chydoridae (. ), , .
  相似文献   

12.
The relative proportions of -helix, -sheet, and unordered form in -lactoglobulin A and B were examined in solutions of urea, guanidine, and sodium dodecyl sulfate (SDS). In the curve-fitting method of circular dichroism (CD) spectra, the reference spectra of the corresponding structures determined by Chen et al. (1974) were modified essentially according to the secondary structure of -lactoglobulin B predicted by Creamer et al. (1983), i.e., that the protein has 17% -helix and 41% -sheet. The two variants showed no appreciable difference in structural changes. The reduction of disulfide bridges in the proteins increased -sheet up to 48% but did not affect the -helical proportion. The -helical proportions of nonreduced -lactoglobulin A and B were not affected below 2 M guanidine or below 3 M urea, but those of the reduced proteins began to decrease in much lower concentrations of these denaturants. By contrast, the -helical proportions of the nonreduced and reduced proteins increased to 40–44% in SDS. The -sheet proportions of both nonreduced and reduced proteins, which remained unaffected even in 6 M guanidine and 9 M urea, decreased to 24–25% in SDS.  相似文献   

13.
Tocotrienols from palm oil showed significant ability to inhibit oxidative damage induced by ascorbate-Fe2+ and photosensitization, involving different mechanisms, in rat liver microsomes. The tocotrienol-rich fraction from palm oil (TRF), being tried as a more economical and efficient substitute for -tocopherol, showed time- and concentration-dependent inhibition of protein oxidation as well as lipid peroxidation. It was more effective against protein oxidation. The extent of inhibition by TRF varied with different peroxidation products such as conjugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Among the constituents of TRF, -tocotrienol was the most effective followed by its - and -isomers. In general, at a low concentration of 5 M, TRF was able to prevent oxidative damage to significant extent (37% inhibition of protein oxidation and 27–30% of lipid peroxidation at 1 h of incubation). The protective ability of TRF (30.1% at 5 M with TBARS formation) was significantly higher than that of the dominant form of vitamin E, -tocopherol (16.5% under same conditions). Hence our studies indicate that this fraction from palm oil can be considered as an effective natural antioxidant supplement capable of protecting cellular membranes against oxidative damage.  相似文献   

14.
Six tetrasaccharide fractions were isolated from shark cartilage chondroitin sulfate D by gel filtration chromatography followed by HPLC on an amine-bound silica column after exhaustive digestion with testicular hyaluronidase. Their structures were determined unambiguously by one- and two-dimensional 500 MHz1H NMR spectroscopy in conjunction with HPLC analysis of chondroitinase AC-II digests of the tetrasaccharides. One fraction was found to contain two tetrasaccharide components. All the seven tetrasaccharides shared the common core structure GlcA1-3GalNAc1-4GlcA1-3GalNAc with various sulfation profiles. Four were disulfated comprising of two monosulfated disaccharide units GlcA1-3GalNAc(4-sulfate) and/or GlcA1-3GalNAc(6-sulfate), whereas the other three were hitherto unreported trisulfated tetrasaccharides containing a disulfated disaccharide unit GlcA(2-sulfate)1-3GalNAc(6-sulfate) and a monosulfated disaccharide unit GlcA1-3GalNAc(4-or 6-sulfate). These sulfated tetrasaccharides were demonstrated to serve as appropriate acceptor substrates for serum -N-acetylgalactosaminyltransferase, indicating their usefulness as authentic oligosaccharide substrates or probes for the glycobiology of sulfated glycosaminoglycans.Abbreviations NFU National formulary unit - COSY correlation spectroscopy - HOHAHA homonuclear Hartmann-Hahn - 1D or 2D one- or two-dimensional - IdoA l-iduronic acid - GlcA d-gluco-4-enepyranosyluronic acid - Di-0S GlcA1-3GalNAc - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-4S GlcA1-3GalNAc(4-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-6S GlcA1-3GalNAc(6-sulfate) - Di-diS d GlcA(2-sulfate)1-3GalNAc(6-sulfate) - Di-diSE GlcA1-3GalNAc(4, 6-disulfate) - U G, U, 2S, 4S, and 6S represent GlcA, GalNAc, GlcA, 2-O-sulfate, 4-O-sulfate, and 6-O-sulfate, respectively  相似文献   

15.
A biocultural study of the side effects of chronic lithium treatment among 70 Hong Kong Chinese psychiatric patients, using a self-report 33-item checklist and semi-structured interviews, revealed an imperfect correspondence between biomedically prescribed and culturally endorsed psychotropic side effects. Although polidipsia and polyuria (47%) were the biomedically most real side effects, they were not usually regarded as bothersome or translated into metaphors to express undesirable side effects.Complaints such as tiredness (38%), drowsiness (36%) and poor memory (31%) were also common but their frequency was significantly lower than that of normal control subjects. The item loss of creativity had no conceptual equivalent in Chinese and was usually misinterpreted. As no patient was aware that lithium was a metal, the side effect metallic taste was variously labelled. Contrary to Western findings, complaints of missing of highs, loss of assertiveness and fear of weight gain were rarely encountered. Active elicitation was required for indigenous complaints, with 38% of patients considering lithium to cause mild hotness. This was readily neutralized by drinking more water which had a cooling effect. Expectedly, concurrent neuroleptics and antidepressants amplified most lithium side effects.This study affirms Western data on the biomedically universalizable effects of chronic lithium treatment, but also supports the thesis that culturally constituted cognitive styles affect patients' recognition, labelling, experiencing and reporting the total drug effect. Further, it demonstrates that the lived experience and clinical negotiation of lithium associated side effects reproduce, authenticate, and at times critique, core cultural and moral premises of Western and Chinese societies.  相似文献   

16.
We examined how hatchlings of the freshwater snail, Pomacea canaliculata, responded to aqueous extracts of conspecific hatchlings. Three, 3-day-old hatchlings were macerated in deionized water (1mg hatchling per 1ml water). When 0.5ml of the aqueous extract was added to a test tube containing 10 hatchlings of the same age and 50ml of water, the hatchlings in the water began to crawl out of the water within 5min. The proportion of hatchlings that crawled out of the water approached 0.6–0.9 after 1h, but gradually decreased to 0.4 after 24h. The relatedness between the live and the macerated hatchlings had no significant influence on the response. Hatchlings of egg masses obtained either in the laboratory or in the wild responded similarly to aqueous extracts of hatchlings from either egg mass. This suggests that the conditions under which the egg masses were incubated or the conditions that their parents had experienced had no effect on the hatchlings response. When compared with experiments reported on other aquatic animals, we consider the behavior of the hatchlings to be an alarm response of escaping from predators.  相似文献   

17.
A contextualizing image (CI) is a powerful central image of a dream which appears to contextualize (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, I was overwhelmed by a tidal wave. This appears to picture their feeling of terror and/or vulnerability.A scoring system for CIs is examined here and is applied to dreams and daydreams supplied by 40 students. Two raters scoring dreams on a blind basis showed good inter-rater reliability. Recent dreams were shown to have more as well as more intense CIs than recent daydreams; likewise, dreams that stand out had more intense CIs than daydreams that stand out. Students with thin boundaries had more and more intense CIs than students with thick boundaries in their recent dreams and nightmare, but not so clearly in dreams and nightmares that stand out. The emotions judged as contextualized by the powerful images tended towards fear/terror and helplessness/vulnerability in dreams (especially in dreams that stand out) whereas emotions contextualized by images in daydreams showed a wide range with no clusters.  相似文献   

18.
1. Forskolin acts as an allosteric modulator of muscle-type nicotinic acetylcholine receptors. Receptors from mouse muscle and Torpedo electroplax demonstrate differential sensitivity to inhibition by forskolin. Previous work from this laboratory suggested that the subunit is responsible for this differential sensitivity.2. We have used a series of mouse/Torpedo species-chimeric subunits to further define the site of forskolin interaction with the subunit. Analysis of the patterns of forskolin inhibition of receptors containing mouse/Torpedo chimeric subunits along with the mouse , , and subunits suggests that forskolin interacts with the small extracellular domain that links the M2 and M3 transmembrane domains (the M2–M3 linker).3. We suggest that the M2–M3 linker domain plays an important role in the transduction of ligand binding to the conformational changes that result in channel opening.  相似文献   

19.
Tanacetan TVF was found to have a branched structure with a backbone of linear -1,4-D-galacturonan. The ramified regions consist of linear -1,2-L-rhamno--1,4-D-galacturonan as the core. The side chains appear to attach to the 4-position of the L-rhamnopyranose residues. They are present as single -galactopyranose residues or a branching -1,4-galactopyranan bearing 4,6-substituted -D-galactopyranose residues as branched points. In addition, the ramified regions contain side chains of a branched -1,5-arabinofuranan possessing 2,5- and 3,5-substituted -L-arabinofuranose residues as branching points. Some side chains of rhamnogalacturonan appear to be arabinogalactan which contains branched sugar chains of -1,5-arabinofuranan attached to the linear chains of -1,4-galactopyranan by 1,3- and 1,6-linkages. The residues of -L-arabinofuranose seem to occupy the terminal positions of the arabinogalactan side chains.  相似文献   

20.
A small protein (Mr about 14 000) rich in cysteine/half-cystine has been isolated from camel milk by exclusion chromatography and reverse-phase high-performance liquid chromatography. The N-terminal amino acid sequence shows a region with several positional identities with and -caseins, which however lack cysteine residues; postions 16–20 are identical and involve the serine residues that have been found to be phosphorylated in -caseins.  相似文献   

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