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1.
The enzymes chlorocatechol-1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase allow Ralstonia eutropha JMP134(pJP4) to degrade chlorocatechols formed during growth in 2,4-dichlorophenoxyacetate or 3-chlorobenzoate (3-CB). There are two gene modules located in plasmid pJP4, tfdC(I)D(I)E(I)F(I) (module I) and tfdD(II)C(II)E(II)F(II) (module II), putatively encoding these enzymes. To assess the role of both tfd modules in the degradation of chloroaromatics, each module was cloned into the medium-copy-number plasmid vector pBBR1MCS-2 under the control of the tfdR regulatory gene. These constructs were introduced into R. eutropha JMP222 (a JMP134 derivative lacking pJP4) and Pseudomonas putida KT2442, two strains able to transform 3-CB into chlorocatechols. Specific activities in cell extracts of chlorocatechol-1,2-dioxygenase (tfdC), chloromuconate cycloisomerase (tfdD), and dienelactone hydrolase (tfdE) were 2 to 50 times higher for microorganisms containing module I compared to those containing module II. In contrast, a significantly (50-fold) higher activity of maleylacetate reductase (tfdF) was observed in cell extracts of microorganisms containing module II compared to module I. The R. eutropha JMP222 derivative containing tfdR-tfdC(I)D(I)E(I)F(I) grew four times faster in liquid cultures with 3-CB as a sole carbon and energy source than in cultures containing tfdR-tfdD(II)C(II)E(II)F(II). In the case of P. putida KT2442, only the derivative containing module I was able to grow in liquid cultures of 3-CB. These results indicate that efficient degradation of 3-CB by R. eutropha JMP134(pJP4) requires the two tfd modules such that TfdCDE is likely supplied primarily by module I, while TfdF is likely supplied by module II.  相似文献   

2.
For the rational design of a stable collagen triple helix according to the conventional rule that the pyrrolidine puckerings of Pro, 4-hydroxyproline (Hyp) and 4-fluoroproline (fPro) should be down at the X-position and up at the Y-position in the X-Y-Gly repeated sequence for enhancing the triple helix propensities of collagen model peptides, a series of peptides were prepared in which X- and Y-positions were altogether occupied by Hyp(R), Hyp(S), fPro(R) or fPro(S). Contrary to our presumption that inducing the X-Y residues to adopt a down-up conformation would result in an increase in the thermal stability of peptides, the triple helices of (Hyp(S)-Hyp(R)-Gly)(10) and (fPro(S)-fPro(R)-Gly)(10) were less stable than those of (Pro-Hyp(R)-Gly)(10) and (Pro-fPro(R)-Gly)(10), respectively. As reported by B?chinger's and Zagari's groups, (Hyp(R)-Hyp(R)-Gly)(10) which could have an up-up conformation unfavorable for the triple helix, formed a triple helix that has a high thermal stability close to that of (Pro-Hyp(R)-Gly)(10). These results clearly show that the empirical rule based on the conformational preference of pyrrolidine ring at each of X and Y residues should not be regarded as still valid, at least for predicting the stability of collagen models in which both X and Y residues have electronegative groups at the 4-position.  相似文献   

3.
Sim GE  Goh CJ  Loh CS 《Plant cell reports》2008,27(8):1281-1289
We analysed the endogenous cytokinin levels of Dendrobium Madame Thong-In seedlings grown in vitro during vegetative and flowering-inductive periods. HPLC was used to fractionate the extracts and radioimmunoassay (RIA) was used for assay of zeatin (Z), dihydrozeatin (DZ), N(6)-(Delta(2)-isopentenyl)-adenine (iP) and their derivatives. Coconut water used in experiments was found to contain high level (>136 pmol ml(-1)) of zeatin riboside (ZR). Protocorms and seedlings cultured in medium with coconut water were found to contain 0.5-3.9 pmol g(-1) FW of the cytokinins analysed. Seedlings (1.0-1.5 cm) cultured in flowering-inductive liquid medium containing 6-benzyladenine (BA, 4.4 muM) and coconut water (CW, 15%) contained up to 200 and 133 pmol g(-1) FW of iP and iPA, respectively. These levels were significantly higher than all other cytokinins analysed in seedlings of the same stage and were about 80- to 150-folds higher than seedlings cultured in non-inductive medium. During the transitional (vegetative to reproductive) stage, the endogenous levels of iP (178 pmol g(-1) FW) and iPA (63 pmol g(-1) FW) were also significantly higher than cytokinins in the zeatine (Z) and dihydrozeatin (DZ) families in the same seedlings. Seedlings that grew on inductive medium but remained vegetative contained lower levels of iPA. The importance of the profiles of iP and its derivatives in induction of in vitro flowering of D. Madame Thong-In is discussed.  相似文献   

4.
Xia Z  Zhuang J 《Luminescence》2012,27(5):379-381
A novel blue‐emitting Sr3.5Y6.5O2(PO4)1.5(SiO4)4.5:Eu2+ phosphor was synthesized via a solid‐state reaction. Powder X‐ray diffraction (XRD) analysis demonstrated that the Sr3.5Y6.5O2(PO4)1.5(SiO4)4.5 host had a hexagonal crystal structure in the space group P63/m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as‐prepared phosphor showed a blue emission and all the main emission peaks were located at around 466 nm for different excitation wavelengths of 297, 333 and 391 nm. The temperature dependence of the photoluminescence property was investigated in the range 20–250 °C, and the emission intensity decreased to 71% of the initial value at room temperature on increasing the temperature to 150 °C. According to the classical theory of fluorescent thermal quenching, the activation energy (ΔE) for the thermal quenching luminescence of the as‐prepared Sr3.45Y6.5O2(PO4)1.5(SiO4)4.5:0.05Eu2+ phosphor was determined to be 0.20 eV. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

5.
The biology of the fruit fly Bactrocera tau, an important horticultural pest, was studied under laboratory conditions at 25°C and 60–70% relative humidity on Cucurbita maxima. The duration of mating averaged 408.03 ± 235.93 min. After mating, the female fly had a preoviposition period of 11.7 ± 4.49 days. The oviposition rate was 9.9 ± 8.50 eggs and fecundity was 464.6 ± 67.98 eggs/female. Eggs were elliptical, smooth and shiny white, turning darker as hatching approached, and measured 1.30 ± 0.07 mm × 0.24 ± 0.04 mm. The chorion has polygonal microsculpturing and is species-specific with polygonal walls. The egg period lasts for 1.3 ± 0.41 days. The duration of the larval period is 1.2 ± 0.42, 1.7 ± 0.48 and 4.0 ± 0.94 days for first, second and third instars, respectively. Pupation occurs in the sand or soil and pupal periods are 7.0 ± 0.47 days. The life cycle from egg to adult was completed in 14.2 ± 1.69 days; the longevity of mated females and males was 130.33 ± 14.18 and 104.66 ± 31.21 days, respectively. At least two to three generations were observed from June 2008 to June 2009.  相似文献   

6.
Mitochondria are well-characterized intracellular organelles usually concentrated in locations of high energy consumption. Light microscopic and transmission electron microscopic observations of the internal anatomy of the feather mites Diplaegidia columbae and Falculifer rostratus were conducted. In the anterior half of the bodies of the mites, we found several dozen of distinctive mitochondria-rich (MR) cells filled with abundant, large mitochondria. Mitochondria are placed individually or enclosed in small groups within an elaborated lamellar system forming a mitochondria–lamellae complex (MLC). The role of the MLC as well as the MR cells is not clear at present, but their involvement in heat generation is hypothesized and briefly discussed.  相似文献   

7.
Summary The rare autosomal fragile site, fra (16)(q22), is the most common of all rare autosomal fragile sites and has a heterozygote frequency of about 5%. Evidence for it was found following the segregation expected from a simple codominant trait with complete penetrance; this is in contrast to a variety of other rare autosomal fragile sites. Based on the analysis of 12 families in which fra (16)(q22) is segregating, we found that, whereas complete penetrance could be confirmed, the transmitting parent was significantly more likely to be of the female sex. On the other hand, there was no evidence for preferential transmission to offspring of either sex.  相似文献   

8.
The aim of the present study was to assess the effect of six different temperatures on the development of Acarophenax lacunatus (Cross & Krantz) using eggs of Tribolium castaneum (Herbst) and Cryptolestes ferrugineus (Stephens) as hosts. The temperature affected the development of A. lacunatus. The largest values for the progeny (19 mites in T. castaneum and 15 mites in C. ferrugineus) were obtained at about 30 degrees C, as also observed for the net reproductive rate (Ro), which revealed that the A. lacunatus population increased 18 times in T. castaneum and 14 times in C. ferrugineus in a generation. The intrinsic rate of increase (r m) gradually increased with temperature, reaching the maximum value at 35 degrees C in T. castaneum (1,608) and C. ferrugineus (1,289). The generation time was negatively correlated with temperature, ranging from 1,60 to 4,85 days in T. castaneum and from 1,96 to 5,34 days in C. ferrugineus. These results suggest that the mite A. lacunatus may be used in programs of biological control of T. castaneum and C. ferrugineus in the tropics.  相似文献   

9.
The origins of capers, their use and cultivation are discussed. Capers seeds and charcoal are often recovered from archaeological sites of the Mediterranean and West Asia. These are referred to as C. Spinosa L. This is mostly a group of cultivars restricted to localities surrounding the Western Mediterranean and some places in the Eastern Mediterranean. Identification of the findings is discussed in terms of seed morphology, present distribution and ancient uses of C. aegyptia Lam., C. sicula Veill., C. cartilaginea Decne, C. orientalis Veill., C. decidua (Forssk.) Edgew. and other species. Citations of Capparis in early Rabbinic, Mesopotamian and Greco-Roman texts are presented. Received June 3, 2002 / Accepted October 8, 2002 Correspondence to: D. Rivera  相似文献   

10.
A mentally retarded girl with a 46,XX/47, XX+r(1) (p11q22q22p11)/47, XX+r(1) (p11q22) fra(1) (p31) fra(1) (p11) fra(1) (q22) karyotype who inherited the fragile sites from the normal mother was studied. The conicidence of fra(1) (p11) and fra(1) (q22) with the ring chromosome breakpoints strongly suggests a cause-effect relationship. This finding agrees with other reported associations between fragile sites and structural chromosome abnormalities and constitutes the fourth reported of a de novo structurally abnormal chromosome as a consequence of presumed in vivo fragile sites instability. Although risk figures for chromosome anomalies and cancer associated with fragile sites are lacking, carriers of fra (1) (p11) may have a higher risk for abnormalities of chromosome 1 in somatic and gonadal cells than the general population.  相似文献   

11.
Synthesis and single crystal X-ray structures of the first paramagnetic transition metal complexes containing chiral ethylenedithio-tetrathiafulvalene-oxazoline (EDT-TTF-OX) 1a-c and ethylenedithio-tetrathiafulvalene-thiomethyloxazoline 2 (EDT-TTF-(SMe)OX) ligands based on copper (II) and cobalt (II) are described. The racemic [EDT-TTF-OX][Cu(hfac)2] complex 3a crystallizes in the triclinic centrosymmetric space group , whereas the enantiopure counterparts 3b-c crystallize in the triclinic non-centrosymmetric space group P1. Cu(II) adopts a distorted square pyramidal coordination geometry, a much weaker Cu?STTF interaction also being identified. The same coordination pattern around Cu(II) is observed in the complex [(rac)-EDT-TTF-(SMe)OX][Cu(hfac)2] (4) in spite of the bidentate nature of the redox active ligand. DFT theoretical calculations afforded two equilibrium configurations for a corresponding model complex, in which the metal centre establishes secondary coordination either with one STTF or with the SMe group. The same ligand coordinates the cobalt (II) to afford the octahedral complex [(rac)-EDT-TTF-(SMe)OX][Co(hfac)2] (5). In all these novel complexes, the paramagnetic centres are structurally and magnetically isolated. Cyclic voltammetry measurements show the stability of the radical cation species.  相似文献   

12.
The interaction between Acarophenax lacunatus (Cross & Krantz) and Anisopteromalus calandrae (Howard) may be a promising tool for the integrated pest management of stored grain insect pests. The objective of this study was to evaluate the compatibility of these two natural enemies on Rhyzopertha dominica (Fabricius). The experimental units were petri dishes (140 x 10 mm) containing 30 g of whole wheat grains (13% water content) infested with 20 adults of R. dominica. The treatments consisted of inoculation of A. lacunatus and A. calandrae, separately and associated, in eight replicates. Three inoculations of five adult females of the natural enemies were carried out in each petri dish at five, ten and fifteen days after the infestation of R. dominica. All treatments were stored during 60 days in environmental chamber at 30 +/- 1 degrees C, 60 +/- 5% relative humidity and 24 h scotophase. The smallest numbers of physogastric females of A. lacunatus and of adults of A. calandrae were obtained when the natural enemies were in association. The use of A. calandrae alone demonstrated a low instantaneous rate of increase (r(i)) of R. dominica and a high protection of the wheat grains. The association of A. calandrae with A. lacunatus led to the lowest number of immatures of R. dominica. These results demonstrate the importance of this interaction as a tool of for the integrated management of R. dominica in stored wheat grains.  相似文献   

13.
Eight specimens of Sericolophus reflexus (Ijima) were compared with the holotype of Hernandeziana ijimae (Hernandez) to assess suspected synonymy of these taxa. An extensive morphometric analysis of the spicules available in these specimens of variable condition show that the H. ijimae holotype exhibits characters near the centre of the range of S. reflexus. It is concluded that H. ijimae is a junior synonym of S. reflexus , and that the family Corythophoridae de Laubenfels is invalid by preoccupation of its base generic name.  相似文献   

14.
Ruthenium(II) tris(bipyridine)-centered poly(ethylenimine) (Ru PEI) was synthesized via acid hydrolysis of Ru tris(bipyridine)-centered poly(2-ethyl-2-oxazoline) (Ru PEOX), and the luminescence, DNA entrapment, and transfection efficiencies were evaluated. Emission maxima for Ru PEI samples are red-shifted compared to Ru PEOX precursors, and the luminescence lifetimes are shorter in both methanol and aqueous solutions. Slower oxygen quenching of Ru PEOX and Ru PEI luminescence versus [Ru(bpy)3]Cl2 (bpy = bipyridine) is attributed to polymer shielding effects. Ru PEI luminescence is similar in the presence and absence of DNA. Ru PEI (7900 Da) and linear PEI (L-PEI; 22,000 Da) fully entrapped DNA (5.4 kb; pcDNA) at an N/P ratio of 2. LNCaP prostate cancer cells were transfected with a plasmid encoding for green fluorescent protein using Ru PEI and L-PEI vectors for comparison. For N/P = 48, the transfection efficiency for Ru PEI was approximately 50% relative to that of L-PEI.  相似文献   

15.
Exechia and Bibio have retained several plesiomorphic groundplan features of Diptera and Bibionomorpha, including a fully exposed and sclerotized head capsule, the transverse undivided labrum, the absence of movable premandibles, and undivided mandibles without combs. The fusion of the hypostomal bridge with the head capsule and largely reduced antennae are derived features shared by both taxa. The absence of teeth at the anterior hypostomal margin is a potential autapomorphy of Bibionomorpha. A basal position of Anisopodidae is suggested by a number of plesiomorphies retained in this family. Apomorphies of Bibionomorpha excluding Anisopodidae are the reduction of tentorial elements, the partial fusion of the labrum and clypeus, one-segmented antennae, the absence of a separate submental sclerite, the loss of the labial palpus, and the reduction of the pharyngeal filter apparatus. Head structures of Bibio are largely unmodified. The subprognathous orientation is one of few autapomorphic features. In contrast, the mouthparts of Exechia are highly modified in correlation with the specialized food uptake. The rasping counterrotating movements of maxillae and mandibles with teeth oriented in opposite directions are carried out by strongly developed extensors and flexors of the paired mouthparts. The modified labium mechanically supports the “drill head” formed by the mandibles und maxillae. The necessary stability of the head capsule is provided by the hypostomal bridge which also compensates the far-reaching reduction of the tentorium.  相似文献   

16.
Autotrophic nutrition plays an important role in adult Tridachiacrispata in the western Atlantic Ocean and results from an endosymbioticassociation between the sacoglossan and the kleptoplastids ofChlorophyta. A series of living specimens 7-80 mm in length was studied inthe laboratory. After a body length of 10 mm has been attained,the parapodial lobes of the two sides meet and fuse. Microscopicexamination of faecal strings of specimens undergoing this transitionrevealed that algal remains were produced only by juvenilesless than 13 mm long. Larger specimens defaecated only rarelyand the diminutive faecal strings contained no recognizablealgal debris. This transition probably parallels the physiologicaltransition between juvenile heterotrophic nutrition and adultautotrophic nutrition. Microscopic examination of the radulae of transitional specimensshowed no diminution of the size, number or morphology of theteeth. This indicates that in an emergency heterotrophic nutritionmay be resumed. Growth rates of Tridachia were measured in the laboratory, withand without light and the provision of algal foods. Unfed animalslost weight rather rapidly in captivity, whereas those fed uponsuitable algae (Halimeda discoidea, Caulerpa verticillata, C.racemosa and Chaetomorpha sp) did not.Caulerpa sertularioideswas suitable for food for a limited time, but proved toxic afterabout a week. Of the other species tested, Caulerpa verticillatawas the least suitable, while Halimeda, Chaetomorpha and Caulerparacemosa were the best. Ironically, C. verticillata was theonly one of the algal species tested which is known to be takenin the natural diet in Floridean waters. These experiments confirmedthat heterotrophic feeding will be resumed in Tridachia if theculture-conditions do not favour autotrophic nutrition.  相似文献   

17.
Abstract. Cis-dichloro-bis (isopropylamine) trans-dihydroxy platinum (IV) (CHIP) is a second generation platinum coordination complex now in Phase II clinical trials. In vitro studies with Chinese Hamster Ovary cell cultures show that CHIP is a phase-sensitive drug, being most cytotoxic to cells in early G1 phase and least toxic to late S and G1 phase cells. the dose-modifying factor between the drug sensitivity of cells treated in G1 and in late S phase is 1.6. These findings and their clinical significance are discussed with respect to the phase sensitivity of other cytotoxic agents.  相似文献   

18.
The acid-base and copper (II) complexing properties of the heteropolynucleotide poly(inosinic)-poly(cytidylic) acid were studied by means of potentiometric, spectrophotometric, CD, and molecular fluorescence titrations in a working aqueous medium of 0.15 M ionic strength at 37°C. The study of the acid-base equilibria has proved the existence of four different species in the pH interval 2–11. Two new species are detected in the presence of copper(II) ion, at acidic and neutral pH values. Spectrophotometric, CD, melting, and fluorescence data were treated with a multivariate curve resolution procedure that allowed the determination of the number of species simultaneously present in each system [acid-base equilibria, copper(II) complexation equilibria], and the estimation of their concentration profiles and of the pure spectra for each species. From the concentration profiles an unambiguous assignment of which species are present at any pH conditions can be made. Furthermore, the knowledge of the pure uv-visible, fluorescence, and CD spectra recovered by the proposed resolution method for each species brings important structural information. When this mathematical approach was applied to the thermal denaturation data, the melting profile and the uv pure spectra for all the different species or conformations formed in the melting process, were calculated. © 1997 John Wiley & Sons, Inc. Biopoly 42: 271–283, 1997  相似文献   

19.
Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.  相似文献   

20.
The functional regulation of integrins is a major determinant of cell adhesion, migration and tissue maintenance. The binding of cytoskeletal proteins to various sites of integrin cytoplasmic domains is a key mechanism of this functional regulation. Expression of recombinant integrin alpha(IIb)beta(3) and alpha(M)beta(2) lacking the GFFKR-region in CHO cells results in constitutively activated integrins. In contrast, CHO cells stably expressing either a GFFKR-deleted alpha(V(del))beta(3) or a FF to AA-substituted alpha(V(AA))beta(3) do not reveal a constitutively activated integrin. Adhesion to immobilized fibrinogen is strongly impaired in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells, whereas it is not impaired in alpha(IIb)beta(3) and alpha(M)beta(2), both lacking the GFFKR-region. In a parallel plate flow chamber assay, alpha(V)beta(3)-expressing cells adhere firmly to fibrinogen and spread even at shear rates of 15 to 20 dyn/cm(2), whereas alpha(V(del))beta(3) or alpha(V(AA))beta(3) cells are detached at 15 dyn/cm(2). Actin stress fiber formation and focal adhesion plaques containing alpha(V)beta(3) are observed in alpha(V)beta(3) cells but not in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells. As an additional manifestation of impaired outside-in signaling, phosphorylation of pp125(FAK) was reduced in these cells. In summary, we report that the GFFKR-region of the alpha(V)-cytoplasmic domain and in particular two phenylalanines are essential for integrin alpha(V)beta(3) function, especially for outside-in signaling. Our results suggest that the two beta(3)-integrins alpha(IIb)beta(3) and alpha(V)beta(3) are differentially regulated via their GFFKR-region.  相似文献   

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