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1.
The cytotoxic ribonuclease -sarcin is a 150-residue protein that inactivates ribosomes by selectively cleaving a single phosphodiester bond in a strictly conserved rRNA loop. In order to gain insights on the molecular basis of its highly specific activity, we have previously determined its solution structure and studied its electrostatics properties. Here, we complement those studies by analysing the backbone dynamics of -sarcin through measurement of longitudinal relaxation rates R1, off resonance rotating frame relaxation rates R1, and the 15N1HNOE of the backbone amide 15N nuclei at two different magnetic field strengths (11.7 and 17.6 T). The two sets of relaxation parameters have been analysed in terms of the reduced spectral density mapping formalism, as well as by the model-free approach. -Sarcin behaves as an axial symmetric rotor of the prolate type (D/D=1.16 ± 0.02) which tumbles with a correlation time m of 7.54 ± 0.02 ns. The rotational diffusion properties have been also independently evaluated by hydrodynamic calculations and are in good agreement with the experimental results. The analysis of the internal dynamics reveals that -sarcin is composed of a rigid hydrophobic core and some exposed segments which undergo fast (ps to ns) internal motions. Slower motions in the s to ms time scale are less abundant and in some cases can be assigned to specific motional processes. All dynamic data are discussed in relation to the role of some particular residues of -sarcin in the process of recognition of its ribosomal target.  相似文献   

2.
W. Hofmann 《Hydrobiologia》1980,73(1-3):255-258
Keratella cochlearis occurs in many Holstein lakes (northern Germany) as three well defined and separated forms: cochlearis, hispida, and tecta, each showing very little variation between the lakes. The present data show that the tecta form did not originate from a Lauterborn cycle.  相似文献   

3.
Summary We describe a case of tertiary trisomy (22q11q) 47,XX,+der(22),(22pter22q13: : 11q2511qter) in a child with mental retardation, cleft palate, and congenital heart disease resulting from 3: 1 meiotic nondisjunction in a maternal (11;22) translocation carrier. The clinical findings in previously reported cases are reviewed and compared with the features of reported patients with partial trisomy 11q and trisomy 22 syndromes. Half of the ten reported families had additional balanced translocation carriers who may have an increased risk of having a liveborn child with an MCA/MR syndrome, although none have been reported to date.  相似文献   

4.
In microbiology the terms viability and culturability are often equated. However, in recent years the apparently self-contradictory expression viable-but-nonculturable (VBNC) has been applied to cells with various and often poorly defined physiological attributes but which, nonetheless, could not be cultured by methods normally appropriate to the organism concerned. These attributes include apparent cell integrity, the possession of some form of measurable cellular activity and the apparent capacity to regain culturability. We review the evidence relating to putative VBNC cells and stress our view that most of the reports claiming a return to culturability have failed to exclude the regrowth of a limited number of cells which had never lost culturability. We argue that failure to differentiate clearly between use of the terms viability and culturability in an operational versus a conceptual sense is fuelling the current debate, and conclude with a number of proposals that are designed to help clarify the major issues involved. In particular, we suggest an alternative operational terminology that replaces VBNC with expressions that are internally consistent.  相似文献   

5.
There are two main designations of protected areas in the UK-nature reserves, of various kinds, and special nature conservation areas, known as Sites of Special Scientific Interest. General approaches to choices of priorities and the resolution of conflict in the management of these areas are described and difficulties identified. Similar problems arise when considering the wider role of protected areas in national nature conservation policies, e.g. biodiversity targets and European Habitats and Species Directive objectives. Because choices and priorities stem from underlying values, the public must be involved in the identification of objectives for both protected areas and the rest of the land surface. The Natural Areas programme being developed by English Nature provides a mechanism whereby people may be involved in characterising the wildlife of their area and in identifying targets for its maintenance and enhancement. The use of land and the management practices associated with it are the major factors influencing the nature conservation value of protected areas and their wider context.English Nature (the Nature Conservancy Council for England) is the statutory advisor to the government on nature conservation in England and promotes the conservation of England's wildlife and natural features.  相似文献   

6.
Summary Differences in reaction to exogenous insulin and adrenalin were studied among chickens of Leghorn, White Rock and Rhode Island Red breeds, using level of blood glucose as indicator of the reaction to hormones. It was found that: 1.) The physiological quantity of glucose in blood in chickens of the three breeds ranged from 157 to 194 mg %. 2.) The reaction of chickens to insulin and adrenalin given alternately, measured by changes of blood glucose, differed according to the breed. The smallest reaction to hormones was in Leghorn, the biggest in White Rock. 3.) The chickens of Leghorn and Rhode Island Red breeds, as well as Leghorn and White Rock breeds, differed significantly in maximal glucose level after adrenalin, 4.) The correlation between the normal quantity of blood glucose and the body weight of birds appeared highly significant in cockerels of all three races combined.  相似文献   

7.
Structures of acidic N-glycans released from porcine zona pellucida glycoproteins by hydrazinolysis were studied. The results indicated that the acidic glycans are of mono- to tetraantennary complex-type with and without N-acetyllactosamine repeating units. Sulfated residues are not only located at the C-6 position of GlcNAc included in the N-acetyllactosamine repeating units, but also at the C-6 position of GlcNAc in the non-repeated antennae and at the C-3 position of reducing terminal GlcNAc residue. Analysis of the oligosaccharide fragments released by endo--galactosidase digestion and by hydrazine/nitrous acid treatment also revealed that various sulfated and non-sulfated forms of fucosylated structures such as Fuc12Gal14(±SO–36)GlcNAc (type 2H), Gal14(Fuc13)(±SO–36)GlcNAc(Lex) and Fuc13 or 4(±SO–36)GlcNAc, are expressed in the repeated outer chain moieties.  相似文献   

8.
Summary The objectives of this study were: (i) to develop a tissue culture technique for the evaluation of Fe efficiency in soybean, and (ii) to compare the laboratory technique with field Fe chlorosis scores. Nineteen genotypes that had low and high levels of Fe efficiency were evaluated in the laboratory and at five field locations. Friable callus was induced from epicotyl sections, weighed, and placed on two different modified Murashige and Skoog media; one low in -naphthaleneacetic acid and the other low in Fe. Callus growth was rated as lack of growth compared to respective controls. As an example, Fe-inefficient cultivars (Asgrow A3205 and Pride B216) had significantly reduced growth compared to Fe-efficient germ plasm lines (All and A14). Correlation between the laboratory and field chlorosis rating was highest for the low auxin medium (r 2 = 0.78), although correlation for the low Fe medium was also significant (r 2 = 0.72). These results show that in vitro evaluation for Fe efficiency can be a useful tool for plant breeders.  相似文献   

9.
Primary structure analysis of the four river buffalo -globin chains showed that haplotypes A and B differ from each other by a substitution at codon 64 that may encode Ala or Asn. The A haplotype encodes two -globin chains, I1 and II3, which differ at positions 129 and 131: I1 has 64 Ala, 129 Phe, 131 Asn; II3 has 64 Ala, 129 Leu, 131 Ser. The B haplotype encodes two -globin chains, I2 and II4, which differ at positions 10 and 11: I2 has 10 Ile, 11 Gln, 64 Asn; II4 has 10 Val, 11 Lys, 64 Asn. Apart from the Ala/Asn polymorphism at position 64, amino acid substitutions in allelic and nonallelic -globin chains seem to have arisen by single point mutations. Detection of electrophoretically silent mutations due to neutral amino acid substitutions and their influence on the isoelectric point are discussed. Furthermore, primary structures of river buffalo -globin chains are compared to other species of the Bovidae family to suggest evolutionary events that have characterized the amino acid substitutions of river buffalo hemoglobin.  相似文献   

10.
The unity of organisms can be viewed in terms of the concepts of enkapsis and complementarity. A model (or a type) represents those properties (of elements, structure, and system) which renders cases - the organisms under consideration — comparable. Comparability is established by operations (or metamorphoses) which relate a case to a model. Therefore, the model and the operations must be enumerated together, if a certain morphology is to be established and applied. Two models, which in some way are related, are conjunct, otherwise they are disjunct. If one model is deducible from the other, they are enkaptic conjunct. If the models are essentially different, that is to say that they cannot be transduced into each other, although they condition each other, they are complementary conjunct: although not comparable themselves, only both together describe a case (or a set of cases) completely. Now, the comparability of a case with two models is considered. The two basic patterns of general comparability are homology and analogy. If the two models are complementary conjunct, nine patterns of special comparability can be distinguished. Each is named in accordance with the general meaning of homology and analogy and, as far as possible, with conventional scientific usage. With minor modifications the terminology also applies to more complicated patterns of comparability including distinct or different conjunct models.  相似文献   

11.
Eli Berger 《Plant and Soil》1976,44(1):201-207
Partitioning the parameters of stony soils in order to express their water content on a volumetric basis, into their pure stone and pure soil constituents, is an important step towards understanding the behavior of such nonhomogeneous systems.The equations derived are exact mathematical identities. Their applications are discussed.Contribution from Agricultural Research Organization, Volcani Center, Bet Dagan, Israel. Serial No. 226-E.  相似文献   

12.
A novel syrup containing neofructo-oligosaccharides was produced from sucrose (Brix 70) by whole cells of Penicillium citrinum. The efficiency of fructo-oligosaccharides production was more than 55% and those of the main carbohydrate components, 1-kestose (Fruf 21Fruf 21 Glc), nystose (Fruf 21Fruf 21 Fruf 21 Glc) and neokestose (Fruf 26 Glc12 Fruf), were 22, 14 and 11%, respectively.  相似文献   

13.
Summary Anoestrous Romney Marsh ewes with or without progesterone pretreatment were injected with multiple low-doses of gonadotrophin-releasing hormone followed by a single, larger bolus. Blood samples were taken at twelve-hourly intervals for progesterone radioimmunoassay. Ewes were slaughtered on day 3 or 5 after the bolus injection, and the ovaries were collected for histology and immunocytochemical examination for oxytocin-immunocreactivity. The corpora lutea of all ewes killed on day 3 had similar weights and morphology. The ovaries of those ewes which were not pretreated with progesterone also contained some luteinized cysts. Ewes slaughtered on day 5 were separated into 2 groups according to plasma progesterone profiles, which were either rising (normal), or falling after a transitory rise (abnormal). Those ewes pretreated with progesterone all had a normal progesterone profile whereas, of 14 ewes not pretreated with progesterone, 6 were normal and 8 abnormal. Corpora lutea were significantly lighter in the abnormal group and the ovaries of most of these ewes also contained luteinized cysts. All corpora lutea and luteinised cysts showed staining for oxytocin-immunoreactivity although the staining intensity was variable. In corpora lutea from normal ewes oxytocin was restricted to large luteal cells. In addition tissues from abnormal ewes also contained many cells with an atypical elongated shape which stained for oxytocin-immunoreactivity. These results show that progesterone pretreatment is needed for both normal morphological and endocrine development of corpora lutea in anoestrous ewes stimulated with gonadotrophin-releasing hormone.  相似文献   

14.
Summary Histochemical and biochemical studies yield the following method of choice for the in situ detection of neutral (microvillous) and acid (lysosomal) -glucosidases: 12 mg 2-naphthyl--D-glucoside (dissolved in 0.5 ml N,N-dimethylformamide) and 0.6–0.8 ml hexazonium-p-rosaniline in 10 ml 0.1 M citric acid phosphate buffer for aqueous or 5 ml buffer mixed with equal parts of 2% agar for incubation with semipermeable membranes, pH 5 or 6.5.With this method neutral -glucosidases can be exactly demonstrated in the brush border of the small intestine (glycoamylase, sucrase-isomaltase) and kidney of mammals, birds, fishes, amphibia and reptiles; localization of acid -glucosidases is achieved at the cellular level in many organs and tissues.Fluorometric and photometric measurements prove that 2-naphthyl--D-glucoside is superior to 6-brom-2-naphthyl--D-glucoside for the demonstration of -glucosidases in situ due to the lower Michaelis constant and higher maximal reaction velocity of the naphthol derivative. — Among the coupling reagents tested neutral -glucosidases can be localized correctly with hexazotized p-rosaniline (with and without semipermeable membranes) for simultaneous coupling. Fast Blue B delivers false positive results in the suczedaneous and simultaneous coupling procedure using aqueous incubation media; in combination with the membrane technique azo dye can not be observed in the sections. Hexazonium-p-rosaniline inhibits neutral and acid -glucosidases to nearly the same extent as Fast Blue B.Fixation of blocks of tissue in formaldehyde and glutaraldehyde suppresses -glucosidases in the intestine and epididymis. The inhibition rates amount to 50 and 70% respectively. Washing in sugar solution rises enzyme activity to 65 and 50%.Species and organ dependent activity differences of neutral and acid -glucosidases and changes of enzyme activity in the intestine and kidney after castration as well as in the course of pregnancy can be detected by means of biochemistry but not with the histochemical assay including minimal incubation. In comparison with p-nitrophenyl--D-glucoside the 2-naphthyl derivative is also the substrate of choice for the biochemical determination of -glucosidases. — Agar gel electrophoresis reveals one band in the neutral and acid pH range.
Histochemische und biochemische Untersuchung der -glucosidasen mit 2-naphthyl--D-glucosid
Zusammenfassung Vergleichend histochemisch-biochemische Untersuchungen ergeben folgende Methode der Wahl zum in situ-Nachweis der neutralen (mikrovillären) und sauren (lysosomalen) -Glucosidasen: 12 mg 2-Naphthyl--D-glucosid (gelöst in 0,5 ml N,N-Dimethylformamid) und 0,6–0,8 ml Hexazonium-p-rosanilin in 10 ml 0,1 M Citronensäure-Phosphat-Puffer zur wäßrigen oder in 5 ml Pufferlösung 1:1 gemischt zur Inkubation mit semipermeablen Membranen, pH 5 und 6,5.Mit diesem Verfahren können die neutralen -Glucosidasen in Bürstensaum von Dünndarm (Glucoamylase, Saccharase-Isomaltase) und Niere bei Säugern, Fischen, Vögeln, Reptilien und Amphibien exakt dargestellt werden; die Lokalisation der sauren -Glucosidase gelingt auf Zellebene in zahlreichen Organen und Geweben.Fluorometrische und photometrische Messungen zeigen, daß 2-Naphthyl--D-glucosid dem Alternativsubstrat 6-Br-2-Naphthyl--glucosid zur histochemischen Untersuchung wegen seiner kleineren Michaelis-Konstante und höheren maximalen Reaktionsgeschwindigkeit überlegen ist. — Unter den geprüften Kupplungssubstanzen kann nur Hexaonium-p-rosanilin als Simultankuppler mit und ohne Membrantechnik vor allem die neutralen -Glucosidasen korrekt erfassen; Fast Blue B in wäßrigen Medien lokalisiert bei Post- und Simultankupplung falsch-positiv und liefert in Verbindung mit semipermeablen Membranen negative Resultate. Die Hemmung der -Glucosidasen durch hexazotiertes p-Rosanilin entspricht etwa der durch Fast Blue B.Stückfixation in Form- und Glutaraldehyd inhibiert die neutralen und sauren -Glucosidasen in Dünndarm und Nebenhoden zu ca. 50 bzw. 70%; nach Auswaschen liegen die Aktivitäten bei 65 bzw. 50%.Art- und organspezifische Aktivitätsdifferenzen der sauren und neutralen -Glucosidasen und Änderungen der Enzymaktivität nach Kastration sowie während der Gravidität in Dünndarm und Niere deckt zuverlässig nur die biochemische Untersuchung auf; der histochemische -Glucosidasen-Nachweis versagt hier selbst bei Minimalinkubation weitgehend. Verglichen mit p-Nitrophenyl--glucosid ist das 2-Naphthylderivat auch das biochemische Substrat der Wahl. — Mittels Agargelelektrophorese kann im alkalischen und sauren pH-Bereich 1 Bande nachgewiesen werden.
  相似文献   

15.
Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE 1,2-diaminoethane - HPLC high pressure liquid chromatography - RNase bovine pancreatic ribonuclease A, EC 3.1.4.22 - TEAB triethylammonium bicarbonate - tris tris(hydroxymethyl)aminomethane - UMP(S) uridine monophosphorothioate - U > p uridine cyclic 2,3-phosphate - U > p(S) uridine cyclic 2,3-O, O-phosphorothioate - Up(S)dT (P-thio)uridylylthymidine - U2p(Rp-S)5dT (P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage  相似文献   

16.
Summary Gene dosage studies yielded results consistent with assignment of the locus for nucleoside phosphorylase to band 14q13. The red blood cells from a patient with the karyotype 47,XX,+der(14),t(8;14)(8qter8q24: :14q2114pter)pat had enzyme activity 50% higher than red cells from 47 normal controls, two trisomies involving chromosomes other than 14, and five balanced translocations involving chromosome 14. On the other hand, the red cells of a case with a karyotype 45,XX,-14,-22,+der(22),t(14;22)(14qter14q11 or 14q12::22p1122qter)mat and a case with a karyotype 47,XX, +der(14),t(14;16)(14pter14q11::16q2416qter)mat had normal activity.  相似文献   

17.
Zeins from Zea mays L cv. Maya and coixins from Coix lacryma-jobi L. cv. Adlay were fractionated to obtain -, -, and -zein and -, -, and -coixin. The -coixins were composed of 4 polypeptide classes of 27 kDa (C1), 25 kDa (C2), 17 kDa (C4) and 15 kDa (C5) with solubility properties very similar to those of the 22 kDa and 19 kDa -zeins. Like the -zeins, the C1 and C2 -coixins corresponded to 80% of total Coix prolamins. The fraction corresponding to -coixin contained only one protein band of 22 kDa (C3). This coixin fraction has solubility properties similar to those of -zein and represents 15% of the total coixin. The -zein fraction was composed of a major 17 kDa protein band, while the -coixin fraction consisted of a mixture of - and -coixins.Polyclonal antibodies raised against C1 recognized C1 and C2 and cross-reacted strongly with the 22 kDa -zein, as did C4 and C5 antisera. The antiserum against -coixin showed strong cross-reaction with -zein. The homology between coixins and zeins was further investigated by using Southern hybridization analyses. The genomic DNA of maize and Coix were digested with several restriction enzymes and probed with cDNA clones representing 19 and 22 kDa -zeins as well as the 28 and 16 kDa -zeins. The Coix genome showed complex cross-hybridization sequences with the 22 kDa -zein cDNA, while no cross-hybridization was observed with the 19 kDa cDNA clone. The cDNA clone representing the 28 kDa -zein cross-hybridized with only one band of Coix genomic DNA, in contrast to the three bands observed in maize. This same Coix sequence also cross-hybridized with the cDNA clone representing the 16 kDa -zein. The relevance of these findings are discussed in the context of the origin of zein and coixin genes.  相似文献   

18.
Summary In a lactic acid fermentation by Streptococcus faecalis, the specific consumption rate of glucose (v) and the specific production rate of lactic acid () were represented by the following simple equations as functions of the specific growth rate (): 1/=(1/) + 1/ = (1/) + By use of data from a batch culture, these two equations were derived from enzyme kinetics of the product inhibition. These equations were successfully applied to the results of batch culture and chemostat culture. In addition, calculation of ATP yield by these equations agreed with the experimental results better than the conventional Leudeking-Piret type equation, which includes two terms associated with growth and not with growth. Correspondence to: H. Ohara  相似文献   

19.
Phoma tracheiphila is the causative agent of the disease mal secco. Citrus cultivars differ substantially in respect to their sensitivity to the pathogenP. tracheiphila and its toxin. Some cultivars (e.g., Femminello lemon) are inherently sensitive while others (e.g., Tarocco orange) are tolerant. Cell lines derived from nucellar tissue of Femminello, Tarocco and a cell line selected for tolerance to the fungal toxin (Femminello-S) were used to study host-pathogen interaction. Our results showed that calli or conditioned media of Tarocco and Femminello-S inhibited the size of co-cultivated fungal colonies when compared to Femminello. In addition, conditioned medium of Tarocco as well as FemminelloS, but not Femminello, promoted bursting of hyphal tips. A ten-fold increase in chitinase and glucanase enzymatic activity, as evaluated by radiometric assay and laminarin hydrolysis respectively, was detected in Femminello-S extracellular extracts as compared to Femminello. An increase in chitinase was also shown by immunoblot analysis. Our findings suggest a positive correlation between the presence of chitinase and glucanase in the conditioned media of the cultured cells and the tolerance of those cells toP. tracheiphila toxin.  相似文献   

20.
Summary Thirteen spontaneously occurring chlorophyll deficient phenotypes have been described and their genetic basis was established. Ten of these — white, white tipped green, patchy white, white virescent, white striping 1, white striping 2, white striping 4, fine striping, chlorina and yellow virescent showed monogenic recessive inheritance and the remaining three — yellow striping, yellow green and light green seedling phenotypes showed digenic recessive inheritance. The genes for (i) white tipped green (wr) and yellow virescent (yv) and (ii) patchy white (pw) and white striping 1 (wst 1) showed independent assortment. Further, the genes for white (w), white tipped green (wr) and yellow virescent (yv) were inherited independently of the gene for hairy leaf margin (Hm).In the mutants — white tipped green, patchy white, white striping 1, white striping 2, fine striping, chlorina, yellow virescent, yellow striping, yellow green and light green phenotypes total quantity of chlorophyll was significantly less than that in the corresponding controls, while in white virescent there was no reduction in the mature stage. For nine of the mutants the quantity of chlorophyll was also estimated in F1's (mutant x control green). In F1's of six of the mutants — white tip, patchy white, chlorina, yellow virescent, fine striping and yellow striping the quantity of chlorophyll was almost equal to the wild type. In the F1's of three of the mutants — white striping 1, white striping 2 and light green an intermediate value between the mutant and wild types was observed. In yellow virescent retarded synthesis of chlorophyll, particularly chlorophyll a was observed in the juvenile stage. Reduced quantity of chlorophyll was associated with defective chloroplasts. In the mutants — white tipped green, white virescent, fine striping, chlorina, yellow striping, yellow green and light green defective plastids were also observed. In patchy white secondary destruction of chlorophylls and the presence of defective plastids were found to be associated with reduced chlorophyll quantity at maturity.Paper chromatographic studies of leaf flavonoids revealed some variation between the inbreds, but there were three common spots, 7, 8 and 9, except for PDP in which the spot 8 was absent. Chlorophyll deficient mutants differed from their respective controls in the absence of one or more of the spots present in the controls and in the presence of new spots in some of the mutants.Most of the chlorophyll mutants showed higher survival rate in the Kharif season than in Rabi season which was attributed to the higher mean day temperature and longer day light period in the Kharif season than in Rabi season.  相似文献   

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