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1.
The daily range of feral goats varied in relation to social class and environmental variables. Mean daily ranges for 5 social classes were: male herd, 3.52 × 105 m2; female herd, 2.12 × 105 m2; composite herd, 1.86 × 105 m2; stayer female, 0.57 × 105 m2; creche group, 0.39 × 105 m2. Total recorded home range was male herd 14.8 × 105 m2 and female herd 9.65 × 105 m2. Female herd daily range varied seasonally in terms of size, location and habitat utilization. Female herd daily range area was correlated significantly with number of days since rain (r = 0.412), amount of rain in the past 30 days (r = ?0.296), maximum daily temperature (r = ?0.409), and minimum daily temperature (r = ?0.523), but not with wind velocity in the morning (r = ?0.064) or afternoon (r = ?0.137).  相似文献   

2.
Two strains of L5178Y mouse lymphoma cells, L5178Y-R (LY-R) and L5178Y-S (LY-S), differ markedly in their sensitivity to 254 nm UV radiation (D0 = 0.7 and 5.5 J/m2; n = 6.0 and 2.0 for LY-R and LY-S cells, respctively). In this study, the frequency o hypoxanthine-guanine-phosporibosyl-transferase-deficient mutants was determined, using 6-thioguanine (TG) as a selective agent, in populations of LY-R and LY-S cells exposed to various fluences of UV radiation. The spontaneous mutation frequency for LY-R cells was (3.7 ± 0.6) × 10?5 TGr mutants per viable cell, and the UV induction rate was (2.2 ± 0.8) × 10?4 TGr mutants per viable cell, per J/m2. Both spontaneous and induced mutantion frequencies were much lower for LY-S cells. The sopntaneous mutation frequency for these cells were too low to make its measurement practicable ( < 0.0013 × 10?5 TGr mutants per viable cell). Mutation induction rate was (4.2 ± 2.2) × 10?7 TGr mutants per viable cell, per J/m2. These differences in mutability do not appear to be due to gene duplication in LY-S cells, or to selective growth disadvantage of LY-S-derived TG-resistant mutants. Possible mechanisms underlying the differences in mutability of LY-R and LY-S cells are considered.  相似文献   

3.
R.M. Simmons 《FEBS letters》1983,164(1):201-204
On incubation of B. subtilis RM125(arg15 leuA8 rM? mM?) with DNA from alkalophilic Bacillus, the transformants (Arg+Leu? or Leu?Arg+) appeared at pH 10. The transformants were able to grow even at pH 7. Alkalophilic Bacillus was resistant to bacteriophages π105D1C2·1012 grown on B. subtilis 1012(r-mM+) and π105D1C2·ISMR4 grown on B. subtilis ISMR4rM+rR+mM+mR+), but the recipient B. subtilis and the transformant(Arg+Leu?) were susceptible to both the of the bacteriophages. The results indicate that the transformant is a B. subtilis derivative and that alkalophilicity of alkalophilic Bacillus was transferred to B. subtilis.  相似文献   

4.
In this study, chlorophyll fluorescence parameters (?F/F m′, F v/F m) and oxygen evolution of female vegetative tissues of Porphyra katadai var. hemiphylla in unisexual culture (FV) and in mixed culture with male vegetative tissues (FV-M) were followed at 5–20 °C, 10 and 80 μmol photons m?2 s?1. The formation of reproductive tissues was closely correlated with decreasing photosynthetic activities. At the same temperature the tissues cultured under 80 μmol photons m?2 s?1 showed a greater extent of maturation than those under 10 μmol photons m?2 s?1, and their decrease in photosynthesis was also larger. Under the same light intensity the extent of maturation increased with increasing temperature, and both cultures showed higher values of ?F/F m′ and F v/F m at 10 and 15 °C, while their oxygen evolution became negative at 15–20 °C during the later period. Under the same culture condition the maturation of FV-M culture was relatively faster than that of FV culture, while their photosynthetic activity, especially ?F/F m′, was lower.  相似文献   

5.
A simple electrophoretic assay demonstrated that peptides from enzymic digests of the basic protein of human myelin were effective substrates for adenosine 3′, 5′-cyclic monophosphate-dependent protein kinases from bovine cardiac muscle and brain. From a peptic digest a peptide of 17 amino acid residues was isolated and when used as a substrate a Km of 1.9 × 10?4M was found for the cardiac kinase.  相似文献   

6.
Chlorophyllase from a diatom alga (Phaeodactylum tricornutum) was obtained and the partially purified extract has been further purified using preparative isoelectric focusing on a Rotofor cell. Three fractions, FI, FII, and FIII, were separated from the Rotofor cell and salt and ampholytes were removed to give fractions FI′, FII′, and FIII′, respectively. Enzyme fractions FI′, FII′, and FIII′, respectively. Enzyme fractions FI′, FII′, and FIII′ showed specific activities of 15.2 × 10?4, 226.7 ×10?4 and 33.8 × 10?4 µmol/mg protein/min, respectively. Most of the enzyme activity (84%) was in fraction FII′. The optimum pH for chlorophyllase activity was 8.0 for FI′ and 8.5 for both FII′ and FIII′. Apparent Km values for enzyme fractions FI′, FII′, and FIII′ were 2.1nM, 2.3nM, and 2.0 nM, respectively. Enzyme fractions FII′ and FIII′ showed higher chlorophyllase activity towards the partially purified chlorophyll when it was compared to that with the crude chlorophyll as well as with both chlorophylls a and b. However, the enzyme fraction FI′ had higher activity towards the crude chlorophyll when it was compared to that with both chlorophylls a and b, but with a preference for chlorophyll a over chlorophyll b. The inhibitory effect of diisopropyl flurophosphate (DIFP) on chlorophyllase activity demonstrates a noncompetitive inhibitor kinetics with Ki values of 1.29mM, 2.14mM, and 0.71mM for FI′. FII′, and FIII′, respectively.  相似文献   

7.
A peptide fragment corresponding to the third helix of Staphylococcus Aureus protein A, domain B, was chosen to study the effect of the main‒chain direction upon secondary structure formation and stability, applying the retro‒enantio concept. For this purpose, two peptides consisting of the native (Ln) and reversed (Lr) sequences were synthesized and their conformational preferences analysed by CD and NMR spectroscopy. A combination of CD and NMR data, such as molar ellipcitity, NOE connectivities, Hα and NH chemical shifts, 3JαN coupling constants and amide temperature coefficients indicated the presence of nascent helices for both Ln and Lr in water, stabilized upon addition of the fluorinated solvents TFE and HFIP. Helix formation and stabilization appeared to be very similar in both normal and retro peptides, despite the unfavourable charge–macrodipole interactions and bad N-capping in the retro peptide. Thus, these helix stabilization factors are not a secondary structure as determined for this specific peptide. In general, the synthesis and confirmational analysis of peptide pairs with opposite main‒chain directions, normal and retro peptides, could be useful in the determination of secondary structure stabilization factors dependent on the direction. © 1997 European Peptide Society and John Wiley & Sons, Ltd.  相似文献   

8.
The Cl?-activated arginine aminopeptidase was purified from human erythrocytes using electrofocusing in granulated gel, gel permeation chromatography, and affinity chromatography. The purified enzyme showed a molecular weight of 105,000 ± 3000 and was homogenous according to several criteria. A subunit structure was revealed during sodium lauryl sulfate electrophoresis, the main form being of Mr 24,500 ± 1300. The enzyme was considered to be a tetramer consisting of four monomers of equal molecular weight. Cl? affected the hydrolysis of peptides and synthetic substrates differently, the Cl? activation being less marked with peptide substrates. The catalysis obeyed regular Michaelis-Menten kinetics and Cl? affected both the Km and V values. Arg-Phe and bradykinin showed no cooperativity in the hydrolysis of Arg-2-naphthylamide catalyzed by the Cl?-activated arginine aminopeptidase. Cl? affected the enzyme structure reflected by changes in the uv-absorption spectra in the presence and without added Cl?.  相似文献   

9.
The biosynthesis of L-tryptophan (L-trp) from anthranilic acid-14C (AA-14C) in. undamaged organs of the seedlings of kohlrabi and pea, with high L-trp content and ma ze plants, with low L-trp content was compared. As for maize the experiments were carried oiut with normal and opaque-2 phenotypes, both with the seedlings and with the ripening kernels. AA-14C is metabolized in the plants to L-trp pool (i.e. free and bound L-trp, and secondary metabolites) and to glycosyl esters of AA (i.e. to simple glucosyl ester in pea and kohlrabi and more complex glycosides in maize). In maize seedlings L-trp-14C is synthesized relatively less. (40% in the 1st and 2nd leaf and 33% in the 3rd leaf of the total radioactivity of the incorporated AA-14C is transferred into the L-trp-14C pool after 24 h) than in kohlrabi (52% in the hypocotyl and 85% in the cotyledons) and in pea (58% in the 1st and the 2nd internode and 85% in the 3rd and the 4th internode). Thede novo formation of L-trp-14C is stoped earlier in maize (after 5 h) than in kohlrabi (after 15 h). The level of free L-trp-14C is relatively low ill maize (15% and 13% of the total radioactivity of the incorporated AA-14C is converted to free L-trp-14C and remains in this form after 24 h) in comparison with kohlrabi (31% and 60%) and pea (30% and 49%). In spite of this the formation of L-trp-14C from AA-14C is sufficient in maize to incorporate L-trp both into the proteins and into a secondary metabolite that is not yet defined. At the period of seedlings the incorporation in maize of L-trp into the proteins (11% and 10% of the activity of the incorporated AA-14C) is comparable with that in kohlrabi (11% and 17%), and it is maximum in pea (29% and 36%). Maize, at the stage of germination, thus forms proteins rich in L-trp. The formation of free L-trp is approximately ten times lower in ripening kernels and in the leaves adjacent to the ear and it further decreases in the course of the ripening of the kernels. Although the activity of the biosynthesis of the AA-14C → L-trp-14C pathway is relatively lower in maize than in kohlrabi and pea, this pathway is most responsible for the differences in the content of L-trp in these plants. Neither amitrol nor histidine affected the biosynthesis of L-trp in kohlrabi; the interaction of the biosynthetic pathways of L-trp and histidine known in microorganisms is thus not important in a higher plant.  相似文献   

10.
An aryl acylamidase (aryl-acylamine amidohydrolase, E.C. 3.5. 1.a) which hydrolyses the herbicide propanil (3′,4′-dichloropropionanilide), was isolated from dandelion roots and partially purified and characterized. Specificity tests on the enzyme revealed that it could hydrolyse various chlorine ring-substituted propionanilides and 3,4-dichloroanilide alkyl compounds. The partially purified enzyme was inhibited by several sulfhydryl reagents and metal ions. The pH optimum was broad, between 7·4 and 7·8. The apparent activation energy, determined from an Arrhenius plot, was 9·0 kcal/mol (37 700 J/mol) for the hydrolysis of 3′,4′-dichloropropionanilide. The apparent Km was 1·7 × 10−4 M with propanil as substrate.  相似文献   

11.
We examine models for evolution of sperm size (i.e. mass m) and number (s) under three mechanisms of sperm competition at low ‘risk’ levels: (i) raffle with no constraint on space available for competing sperm, (ii) direct displacement mainly by seminal fluid, and (iii) direct displacement mainly by sperm mass. Increasing sperm mass increases a sperm's ‘competitive weight’ against rival sperm through a diminishing returns function, r(m). ESS total ejaculate expenditure (the product m?s?) increases in all three models with sperm competition risk, q. If r(m), or ratio r′(m)/r(m), is independent of ESS sperm numbers, ESS sperm mass remains constant, and the sperm mass/number ratio (m?/s?) therefore decreases with risk. Dependency of sperm mass on risk can arise if r(m) depends on competing sperm density (sperm number / space available for sperm competition). Such dependencies generate complex relationships between sperm mass and number with risk, depending both on the mechanism and how sperm density affects r(m). While numbers always increase with risk, mass can either increase or decrease, but m?/s? typically decreases with risk unless sperm density strongly influences r(m). Where there is no extrinsic loading due to mating order, ESS paternity of the second (i.e. last) male to mate (P2) under displacement always exceeds 0.5, and increases with risk (in the raffle P2=0.5). Caution is needed when seeking evidence for a sperm size-number trade off. Although size and number trade-off independently against effort spent on acquiring matings, their product, m?s?, is invariant or fixed at a given risk level, effectively generating a size-number trade off. However, unless controlled for the effects of risk, the relation between m? and s? can be either positive or negative (a positive relation is usually taken as evidence against a size-number trade off).  相似文献   

12.
《Phytochemistry》1987,26(4):1155-1158
The stem bark of Ocotea veraguensis has yielded nine neolignans of which five appear to be novel. The new neolignans, which were identified on the basis of spectral characteristics, are* (7S,8R,1′S,2′S,3′R,4′S)-Δ8′-2′,4′-dihydroxy-3,3′5′-trimethoxy-4,5-methylenedioxy-1′,2′,3′,4′-tetrahydro-7.3′,8.1′-neolignan, (7S,8R,1′S,3′S,4′S)-Δ8′-4,4'-dihydroxy-3,3′,5′-trimethoxy-1′,2′,3′,4′-tetrahydro-2′-oxo-7.3′,8.1′-neolignan, (7S,8S,1′R)-Δ8′-3′,5′-dimethoxy-3,4-methylenedioxy-1′,4′-dihydro-4′-oxo-7.0.2′,8.1′-neolignan, (7S,8S,1′R )-Δ8′-1′-methoxy-3,4-methylenedioxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-neolignan and (7S,8S)-Δ8′-2′,6′-dimethoxy-3,4-methylenedioxy-7.0.3′,8.4′,1′.0.7′-neolignan.  相似文献   

13.
A simple procedure, exploiting an affinity chromatography step on agarose-linked adenosine 2′,5′-bisphosphate, allows the concurrent purification from human red cell lysates of glucose 6-phosphate dehydrogenase (G6PD) and of another protein (FX). The latter, which has a higher electrophoretic mobility than G6PD, is not identifiable with any of a number of erythrocyte enzymes. It is a holoprotein, composed in its native form of two polypeptide chains of 33,000 Mr each and of one NADP equivalent. Native FX binds NADPH and this binding is competitive with NADP: The corresponding stoichiometry is 0.5 NADPH equivalents per 33,000 Mr (“half-site reactivity”), with a dissociation constant of 1 × 10?8m. On the basis of competition experiments, the dissociation constant for NADP is estimated to be 1.8 × 10?7m.  相似文献   

14.
Incubating rat fat cell membranes with [32P]NAD+ and cholera toxin results in ADP-ribosylation of three distinct components with approximate molecular weights of 42 000, 46 000 and 48 000. Partial proteolytic peptide maps of the Mr = 46 000 and 48 0000 toxin-specific substrates generated by elastase, α-chymotypsin, or Staphylococcus aureus V-8 protease were nearly identical, while those of the Mr = 42 000 target lacked several peptides common to both of the larger molecular weight targets. In addition, peptide maps generated from the Mr = 42 000 target displayed a number of peptides which were absent from the maps generated from either the Mr = 46 000 or 48 000 targets. These data suggest that the Mr = 46 000 and 48 000 substrates are closely related proteins, however the relationship between the Mr = 42 000 toxin-specific substrate and the larger peptides remains to be established. The relative patterns of fat cell membrane labelling by cholera toxin in the presence of [32P]NAD+  相似文献   

15.
Encarsia tricolor Foërster is a facultative autoparasitoid that develops on the important pestTrialeurodes vaporariorum (Westwood) in outdoor crop conditions, which makes this aphelinid species promising for biological control programs in regions where field and protected crops coexist. In this paper we report the results obtained in the study of daily and totalE. tricolor egg laying and of adult female preference for different host stages in which to lay eggs at constant temperatures in the range 10 to 32 °C. Only whitefly nymphs were present in the searching arena (tomato leaflets). The mean number of eggs laid per female in one day ranged from 4.0 (10 °C and 32 °C) to 15.2 (24 °C). The mean total number of eggs increased with temperature from 10 to 28 °C, reaching a maximum of 123 eggs per female at 28 °C, and decreased sharply from 28 to 32 °C. The relation between the intrinsic rate of increase (rm) and temperature in the range 10 to 28 °C followed a straight line whose equation was rm=?0.076+0.011*T (R2=0.99). The rm ofE. tricolor was greater than the rm ofT. vaporariorum when temperature was higher than 9.2 °C. The preference for any particular host instar in which to lay eggs was not always significant. However, N4 was the host instar preferred whenever preference was statistically significant.  相似文献   

16.
Cyclic adenosine 3′,5′-monophosphate and N6-2′-O-dibutyryl cyclic adenosine 3′,5′-monophosphate increase the accumulation of α-methyl-d-glucoside by cortical slices from rat, rabbit, dog and human kidney. The characteristics of the effect have been studied in rat tissue. At least 90 min of exposure of the tissue to cyclic nucleotide prior to onset of glucoside accumulation is required as well as presence of the cyclic nucleotide during the accumulation phase. Inhibition of protein synthesis does not abolish the effect of N6-2′-O-dibutyryl cyclic adenosine 3′,5′-monophosphate. The cyclic nucleotide causes an increase in the initial entry rate of α-methyl-d-glucoside into cells and an increase in the intracellular steady state concentration. The cyclic nucleotide does not affect the apparent Km of the glucoside entry process but increases the maximum velocity of accumulation.  相似文献   

17.
Phosphatidyl inositol and lysophosphatidyl choline have been identified as activators of a partially purified brain cyclic nucleotide phosphodiesterase previously shown to be regulated in vitro by Ca2+ and a Ca2+-binding protein. Microgram quantities of either phospholipid produced a linear, immediate and reversible activation of the enzyme in the absence of Ca2+ and the Ca2+-dependent regulator (CDR). Fatty acids were also found to activate the phosphodiesterase to varying degrees, with oleic acid being the most effective. Phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine and lysophosphatidyl ethanolamine were not effective as activators. Only sodium dodecyl sulfate, of a variety of nonionic, cationic, and anionic detergents tested, activated the phosphodiesterase. Sodium dodecyl sulfate produced a modest degree of activation over a narrow concentration range, followed by enzyme denaturation at higher concentrations.The interaction of the phosphodiesterase with the phospholipid activators has been compared to its interaction with the Ca2+·CDR complex. Both Ca2+·CDR and lysophosphatidyl choline decreased the thermal stability of the enzyme to a similar extent. The apparent Km of the lysophosphatidyl choline-dependent phosphodiesterase activity was approximately 30 μm with guanosine-3′,5′-monophosphate (cGMP) as substrate and 1 mm with adenosine-3′,5′-monophosphate (cAMP) as substrate. With increasing lysophosphatidyl choline concentration, the apparent Km for each nucleotide remained unchanged while the V increased. The apparent Kd for Mg2+ of the lysophosphatidyl choline-dependent phosphodiesterase activity was approximately 3 μm and was unaffected by lysophosphatidyl choline concentration. Activation of the phosphodiesterase by lysophosphatidyl choline was characterized by a high degree of positive cooperativity, exhibiting a Hill coefficient of 3.8. Fluphenazine was a competitive inhibitor of both Ca2+·CDR and lysophosphatidyl choline activation of the enzyme.  相似文献   

18.
The crystal and molecular structure of methyl 2,3,4,6,2′,4′,6′-hepta-O-acetyl β-laminarabioside has been determined by X-ray diffraction. The crystal belongs to the orthorhombic system space group P212121,a 10.471 (1), b 22.482(1), c 13.647(1) Å, Dm 1.33 g.cm?3, Z 4. The structure was established by the direct method and refined by the block-diagonal, least-squares procedure to R 0.093 for 2043 observed reflections. Difference synthesis showed all the hydrogen atoms except the methyl hydrogen ones. The molecule shows a fully-extended conformation and has no intra-molecular hydrogen bond. The ring-to-ring conformation can be described.as (φψ)  (42.5, 4.7°), according to the definition of Sathyanarayana and Rao, and it is compared with (φψ)  (27.9, ?37.5°) of laminarabiose. There is no inter-molecular hydrogen bond. The d-glucopyranose rings of the molecule are piled up along the a axis and approximately parallel to the bc-plane. Each of the acetyl groups is approximately perpendicular to the d-glucopyranose ring.  相似文献   

19.
The concentration and distribution characteristics of airborne fungi were investigated in indoor and outdoor air of two metro stations (Imam Khomeini and Sadeghiyeh stations) in Tehran subway. Samples were taken from indoor air at each station from platform and ticket office area also from adjacent outdoor air of each station. Indoor sampling was conducted for two types of trains, old and new. The concentration of airborne fungi ranged from 21 CFU/m3 at the outdoor air of Imam Khomeini station to 1,402 CFU/m3 in the air samples collected from the platform of this station. Results showed that airborne fungi concentrations at indoor air were higher than the outdoor air (p < 0.05), and fungal levels significantly correlated with the number of passengers (p < 0.05; r = 0.68) and RH % (p < 0.05; r = 0.43). Sixteen genera of fungi were isolated in all sampled environments. The predominant genera identified in indoor and outdoor air were Penicillium spp. (34.88 % of total airborne fungi) and Alternaria spp. (29.33 % of total airborne fungi), respectively. The results of this study showed that the indoor air quality in subway is worse than the outdoor air.  相似文献   

20.
Arterenone (2-amino-3′,4′-dihydroxy acetophenone) is an important hydrolytic product generated from lightly colored sclerotized cuticle that use N-acyldopamine derivatives for crosslinking reactions. It seems to arise from 1,2-dehydro-N-acetyldopamine (dehydro NADA) that has been crosslinked to the cuticular components. However, the mechanism of generation of arterenone, which has two protons on the α-carbon and no proton on the β-carbon atom from dehydro NADA crosslinks that have one proton each on these two side chain carbons, remained elusive and undetermined. To investigate the mechanism of this transformation, we synthesized specifically labeled β-deuterated dehydro NADA and incubated with Sarcophaga bullata cuticle undergoing larval puparial transformation. We also isolated the dimeric products formed during the tyrosinase-mediated oxidation of dehydro NADA. Hydrolysis of both β-deuterated dehydro NADA treated cuticle and β-deuterated dehydro NADA dimer generated arterenone as the major hydrolytic product. Liquid chromatography-mass spectrometric analysis of this arterenone revealed the retention of deuterium from the β-position of dehydro NADA at the α-carbon atom of arterenone. Hydrolysis of β-deuterated dehydro NADA also generated the labeled arterenone under oxidative conditions, but not under anaerobic conditions. These results indicate the unique hydride shift from β-carbon to α-carbon during acid hydrolysis and reveal the mechanism of liberation of arterenone and related compounds from dehydro NADA linked cuticle.  相似文献   

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