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1.
All species that have been described of the genera mentioned in the title are listed and their systematic position given. The species of Stilifer (with 11 species, including S. inflatus sp.n. and 5. concavus sp.n.) are parasites of starfishes. Scalenostoma (3 species) are parasites of stone corals. Thyca (with 8 species) is removed from Capulidae, and included in Eulimidae. T. hawaiiensis sp.n. is described. The species of Thyca are parasites of starfishes. The species of Mucronalia (including M. trilineata sp.n.) are probably parasites of ophiuroids and Echineulima (with 4–6 species, including E. ponderi sp.n.) are parasites of echinoids. All species are figured, their characteristics are given and their host species and distributions are listed. Keys are given to the species of each genus, except Mucronalia. The genera Stilimella Laseron and Hyperlia Pilsbry are synonymized with Scalenostoma and the genera Kiramodulus Kuroda, Granulithyca Habe and Bessomia Berry are considered subgenera of Thyca.  相似文献   

2.
Gunning BE 《Protoplasma》2005,225(1-2):33-42
Summary. Stromules are stroma-containing tubules which can grow from the surface of plastids, most commonly leucoplasts and chromoplasts, but also chloroplasts in some tissues. Their functions are obscure. Stills from video rate movies are presented here. They illustrate interaction of stromules with cytoskeletal strands and the anchoring of stromules to unidentified components at the cell surface. Anchoring leads to stretching and relaxation of stromules when forces arising from cytoplasmic streaming act on the attached, freely suspended plastid bodies. Data on stromule growth, retraction, and regrowth rates are provided. Formation and movement of stromular branches and bridges between plastids are described. The shedding of a tip region into the streaming cytoplasm is recorded in frame-by-frame detail, in accord with early observations. Correspondence and reprints: Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia.  相似文献   

3.
Abstract Eight families of Symphyta for the Western Hemisphere south of the United States are reviewed: Xyelidae (one genus, two species), Pamphiliidae (one genus, four species), Cimbicidae (five genera, nine species), Diprionidae (three genera, thirteen species), Xiphydriidae (four genera, seventeen species), Siricidae (six genera, nine species), Orussidae (five genera, twelve species), and Cephidae (one genus, one species). New taxa are Acantholyda nigrostigmata (Pamphiliidae); Zadiprionfalsus, Neodiprion bicolor, N.equalis, N.omosus (Diprionidae); Derecyrta circularis, Steirocephala lateralba (Xiphydriidae); Sirotremex, S.flammeus (Siricidae); and Ophrynopus depressatus, O.plaumanni (Orussidae). Lopesiana is a new name for Lopesia Conde (Cimbicidae). Three new combinations and six new synonyms are proposed. The Xyelidae, Pamphiliidae, Diprionidae, Siricidae and Cephidae are primarily northern groups with southern extensions into Mexico, Central America and/or Cuba. The Cimbicidae, Xiphydriidae and Orussidae are more generally distributed throughout the neotropics. Keys to families, genera and species are provided.  相似文献   

4.
Production, purification, characterization, and applications of lipases   总被引:45,自引:0,他引:45  
Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of esters formed from glycerol and long-chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. The many applications of lipases include speciality organic syntheses, hydrolysis of fats and oils, modification of fats, flavor enhancement in food processing, resolution of racemic mixtures, and chemical analyses. This article discusses the production, recovery, and use of microbial lipases. Issues of enzyme kinetics, thermostability, and bioactivity are addressed. Production of recombinant lipases is detailed. Immobilized preparations of lipases are discussed. In view of the increasing understanding of lipases and their many applications in high-value syntheses and as bulk enzymes, these enzymes are having an increasing impact on bioprocessing.  相似文献   

5.
A rapid and sensitive method for separation and concurrent assay of 14 compounds at the picomole level in individual rat brain parts is described. The putative amino acid neurotransmitters (aspartate, γ-aminobutyric acid, glutamate, and glycine) are extracted from a 20–30 mg portion of the tissue with 5% TCA and assayed as their respective DNP-amino acid methyl ester derivatives by glc. Four other putative neurotransmitters (acetylcholine, dopamine, norepinephrine, and serotonin) and some of their precursors and metabolites (choline, tryptophan, 5-hydroxytryptophan, 5-hydroxyindoleacetic acid, and tyrosine) are extracted in 1n formic acid-acetone (v/v:15/85) from the remaining tissue. The lipids are removed with a heptane-chloroform (v/v:8/1) wash and the aqueous phase is dried at 37°C under N2. The dried extract is dissolved in water (pH 4). With one portion of this solution, acetylcholine and choline are assayed using a radioenzymatic method whereas with the rest, dopamine, norepinephrine, serotonin, 5-hydroxyindoleacetic acid, 5-hydroxytryptophan, tryptophan, and tyrosine are separated with three ion exchange resins arranged in tandem. These compounds are assayed fluorometrically with modified microadaptations of previously reported methods.  相似文献   

6.
It has been demonstrated that fibroblast growth factor receptors are key regulators of endochondral bone growth. However, it has not been determined what fibroblast growth factor ligand(s) (FGFs) are important in this process. This study sought to determine whether FGFs 1, 2, 4, 5, 6, 7, 8, 9, and 10 were capable of stimulating avian chondrocyte proliferation in vitro. We have found that FGFs 2, 4, and 9 strongly stimulate avian chondrocyte proliferation while FGFs 6 and 8 stimulate proliferation to a lesser extent. RT-PCR indicates that FGF-2 and FGF-4 are expressed in the postnatal avian epiphyseal growth plate (EGP) while FGF-8 and FGF-9 are not. Thus, FGF-2 and FGF-4 stimulate chondrocyte proliferation and are both present in the EGP. This suggests that FGF-2 and FGF-4 may be important ligands, in vivo, for the regulation of endochondral bone growth. These observations coupled with our observation that multiple avian FGF receptors (Cek1, Cek2, Cek3, and FREK) are expressed in proliferative chondrocytes highlights the complexity of FGF signaling pathways in postnatal endochondral bone growth.  相似文献   

7.
Nodes in networks are often of different types, and in this sense networks are differentiated. Here we examine the relationship between network differentiation and network size in networks under economic or natural selective pressure, such as electronic circuits (networks of electronic components), Legos (networks of Lego pieces), businesses (networks of employees), universities (networks of faculty), organisms (networks of cells), ant colonies (networks of ants), and nervous systems (networks of neurons). For each of these we find that (i) differentiation increases with network size, and (ii) the relationship is consistent with a power law. These results are explained by a hypothesis that, because nodes are costly to build and maintain in such "selected networks", network size is optimized, and from this the power-law relationship may be derived. The scaling exponent depends on the particular kind of network, and is determined by the degree to which nodes are used in a combinatorial fashion to carry out network-level functions. We find that networks under natural selection (organisms, ant colonies, and nervous systems) have much higher combinatorial abilities than the networks for which human ingenuity is involved (electronic circuits, Legos, businesses, and universities). A distinct but related optimization hypothesis may be used to explain scaling of differentiation in competitive networks (networks where the nodes themselves, rather than the entire network, are under selective pressure) such as ecosystems (networks of organisms).  相似文献   

8.
We report 19 new species records for the faunal list of Coleoptera in New Brunswick, Canada, six of which are new records for the Maritime provinces, and one of which is new Canadian record. We also provide the first recent records for five additional species in New Brunswick. One new species of Stenotrachelidae, Cephaloon ungulare LeConte, is added to the New Brunswick faunal list. Additional records are provided for Cephaloon lepturides Newman, as well the first recent record of Nematoplus collaris LeConte. Two species of Oedemeridae, Asclera puncticollis (Say) and Asclera ruficollis (Say), are newly reported for New Brunswick, and additional locality and bionomic data are provided for Calopus angustus LeConte and Ditylus caeruleus (Randall). The records of Ditylus caerulus are the first recent records for the province. Three species of Meloidae, Epicauta pestifera Werner, Lytta sayi LeConte, and Meloe augustcollis Say are reported the first time for New Brunswick; Epicauta pestifera is newly recorded in Canada. Lacconotus punctatus LeConte and the family Mycteridaeis newly recorded for New Brunswick. The first recent records of Borus unicolor Say (Boridae) are reported from the province. One new species of Pythidae, Pytho siedlitzi Blair, and the first recent records of Pytho niger Kirby are added to the faunal list of New Brunswick. Three species of Pyrochroidae are newly reported for the province, including Pedilus canaliculatus (LeConte) and Pedilus elegans (Hentz), which are new for the Maritime provinces. Five species of Anthicidae and the first recent record of Anthicus cervinus LaFerté-Sénectére are newly reported for New Brunswick. Anthicus melancholicus LaFerté-Sénectère, Sapintus pubescens (LaFerté-Sénectère), Notoxus bifasciatus (LeConte), and Stereopalpus rufipes Casey are new to the Maritime provinces faunal list. Ambyderus granularis (LeConte) is removed from the faunal list of the province. Three species of Aderidae, Vanonus huronicus Casey, Zonantes fasciatus (Melsheimer), and Zonantes pallidusWerner, are newly recorded for New Brunswick; Zonantes fasciatus and Vanonus huronicus are new for the Maritime provinces' faunal list. Collection data, bionomic data, and distribution maps are presented for all these species.  相似文献   

9.
Morphological analyses of seed plant phylogeny agree that Gnetales are the closest living relatives of angiosperms, but some studies indicate that both groups are monophyletic, while others indicate that angiosperms are nested within Gnetales. Molecular analyses of several genes agree that both groups are monophyletic, but differ on whether they are related. Conflicts among morphological trees depend on the interpretation of certain characters; when these are analyzed critically, both groups are found to be monophyletic. Conflicts among molecular trees may reflect the rapid Paleozoic radiation of seed plant lines, aggravated by the long branches leading to extant taxa. Trees in which angiosperms are not related to Gnetales conflict more with the stratigraphic record. Even if molecular data resolve the relationships among living seed plant groups, understanding of the origin of angiosperm organs will require integration of fossil taxa, necessarily using morphology.  相似文献   

10.
Electron attachment rates and gas phase acidities for the canonical tautomers of the nucleobases and electron affinities for thymine, deprotonated thymine, and cytosine are reported The latter are from a new analysis of published photoelectron spectra. The values for deprotonated thymine are (all in eV) keto-N1-H, 3.327(5); enol-N3-H, 3.250(5), enol-C2OH, 3.120(5) enol-N1-H, 3.013(5), and enol-C4OH,3.123(5). The values for deprotonated cytosine, keto-N1-H, 3.184(5); trans-NH-H, 3.008(5); cis-NH-H, 3.039(5); and enol-N1-H, 2.750(5) and enol-O-H, 2.950(5). The gas phase acidities from these values are obtained from these values using experimental or theoretical calculations of bond dissociation energies. Kinetic and thermodynamic properties for thermal electron attachment to thymine are obtained from mass spectrometric data. We report an activation energy of 0.60 eV and electron affinity of thymine, 1.0(1) eV.  相似文献   

11.
The literature on chemical (i.e., nonenzymic) phosphorylation of amino acids, peptides, and proteins is reviewed through 1982. The review covers synthetic methods, chemical reactions, and physical properties, with emphasis on the techniques used for separation and characterization of the products. Synthetic methods are classified by reagent rather than product, and are illustrated by experimental procedures for the most important methods. Chemical reactions are classified into four groups depending on whether the reaction site is the phospho group, the amino group, the carboxyl group, or in the case of serine the hydroxyl group. Physical data are given for all of the known N-, O-, and S-phospho derivatives of the amino acids, peptides, and proteins, within certain limitations, and are discussed in detail in the section on physical properties. Emphasis is given to the techniques used for separation of the products, such as chromatography and electrophoresis, and for characterization of the products, particularly spectroscopy. Medical and other uses of the products are mentioned.  相似文献   

12.
Electron attachment rates and gas phase acidities for the canonical tautomers of the nucleobases and electron affinities for thymine, deprotonated thymine, and cytosine are reported The latter are from a new analysis of published photoelectron spectra. The values for deprotonated thymine are (all in eV) keto-N1-H, 3.327(5); enol-N3-H, 3.250(5), enol-C2OH, 3.120(5) enol-N1-H, 3.013(5), and enol-C4OH,3.123(5). The values for deprotonated cytosine, keto-N1-H, 3.184(5); trans-NH-H, 3.008(5); cis-NH-H, 3.039(5); and enol-N1-H, 2.750(5) and enol-O-H, 2.950(5). The gas phase acidities from these values are obtained from these values using experimental or theoretical calculations of bond dissociation energies. Kinetic and thermodynamic properties for thermal electron attachment to thymine are obtained from mass spectrometric data. We report an activation energy of 0.60 eV and electron affinity of thymine, 1.0(1) eV.  相似文献   

13.
Piotrowska A  Bajguz A 《Phytochemistry》2011,72(17):2097-2112
Phytohormones, including auxins, abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellins, and jasmonates, are involved in all aspects of plant growth, and developmental processes as well as environmental responses. However, our understanding of hormonal homeostasis is far from complete. Phytohormone conjugation is considered as a part of the mechanism to control cellular levels of these compounds. Active phytohormones are changed into multiple forms by acylation, esterification or glycosylation, for example. It seems that conjugated compounds could serve as pool of inactive phytohormones that can be converted to active forms by de-conjugation reactions. Some conjugates are thought to be temporary storage forms, from which free active hormones can be released after hydrolysis. It is also believed that conjugation serves functions, such as irreversible inactivation, transport, compartmentalization, and protection against degradation. The nature of abscisic acid, brassinosteroid, ethylene, gibberellin, and jasmonate conjugates is discussed.  相似文献   

14.
Fluorene and its three heteroatomic analogs, dibenzofuran, dibenzothiophene, and carbazole, are environmental contaminants in areas impacted by spills of creosote. In addition, dibenzofuran has been used as an insecticide, and it is formed from the photolysis of chlorinated biphenyl ethers. Many biodegradation studies of dibenzofuran have considered it as a model for chlorinated dibenzofurans, which are of greater environmental concern. This paper reviews the bacterial degradation of fluorene and its analogs. These compounds are susceptible to three different modes of initial oxidation: (i) the naphthalene-like attack, in which one of the aromatic rings is oxidized to a dihydrodiol; (ii) an angular dioxygenase attack, in which the carbon bonded to the methylene group in fluorene or to the heteroatoms in the analogs, and the adjacent carbon in the aromatic ring are both oxidized; and (iii) the five-membered ring attack, in which the methylene carbon atom in fluorene or the sulfur atom in dibenzothiophene is oxidized. The metabolites, enzymology, and genetics of these transformation are summarized. Literature data are presented, indicating that the electronegativity of the atom connecting the two aromatic rings influences the attack of the angular dioxygenase. In dibenzofuran and carbazole, the connecting atoms, O and N respectively, have high electronegativities, and these compounds serve as substrates for angular dioxygenases. In contrast, the connecting atoms in dibenzothiophene and fluorene, S and C respectively, have lower electronegativities, and these atoms must be oxidized before the angular dioxygenases attack these compounds.  相似文献   

15.
In food-web studies, parasites are often ignored owing to their insignificant biomass. We provide evidence that parasites may affect trophic transfer in aquatic food webs. Many phytoplankton species are susceptible to parasitic fungi (chytrids). Chytrid infections of diatoms in lakes may reach epidemic proportions during diatom spring blooms, so that numerous free-swimming fungal zoospores (2-3 microm in diameter) are produced. Analysis shows that these zoospores are rich in polyunsaturated fatty acids and sterols (particularly cholesterol), which indicates that they provide excellent food for zooplankters such as Daphnia. In life-table experiments using the large diatom Asterionella formosa as food, Daphnia growth increased significantly in treatments where a parasite was present. By grazing on the zoospores, Daphnia acquired important supplementary nutrients and were able to grow. When large inedible algae are infected by parasites, nutrients within the algal cells are consumed by these chytrids, some of which, in turn, are grazed by Daphnia. Thus, chytrids transfer energy and nutrients from their hosts to zooplankton. This study suggests that parasitic fungi alter trophic relationships in freshwater ecosystems and may be the important components in shaping the community and the food-web dynamics of lakes.  相似文献   

16.
Li C  Wang E  Wang J 《Biophysical journal》2011,(6):1335-1344
Circadian rhythms with a period of ∼24 h, are natural timing machines. They are broadly distributed in living organisms, such as Neurospora, Drosophila, and mammals. The underlying natures of the rhythmic behavior have been explored by experimental and theoretical approaches. However, the global and physical natures of the oscillation under fluctuations are still not very clear. We developed a landscape and flux framework to explore the global stability and robustness of a circadian oscillation system. The potential landscape of the network is uncovered and has a global Mexican-hat shape. The height of the Mexican-hat provides a quantitative measure to evaluate the robustness and coherence of the oscillation. We found that in nonequilibrium dynamic systems, not only the potential landscape but also the probability flux are important to the dynamics of the system under intrinsic noise. Landscape attracts the systems down to the oscillation ring while flux drives the coherent oscillation on the ring. We also investigated the phase coherence and the entropy production rate of the system at different fluctuations and found that dissipations are less and the coherence is higher for larger number of molecules. We also found that the power spectrum of autocorrelation functions show resonance peak at the frequency of coherent oscillations. The peak is less prominent for smaller number of molecules and less barrier height and therefore can be used as another measure of stability of oscillations. As a consequence of nonzero probability flux, we show that the three-point correlations from the time traces show irreversibility, providing a possible way to explore the flux from the observations. Furthermore, we explored the escape time from the oscillation ring to outside at different molecular number. We found that when barrier height is higher, escape time is longer and phase coherence of oscillation is higher. Finally, we performed the global sensitivity analysis of the underlying parameters to find the key network wirings responsible for the stability of the oscillation system.  相似文献   

17.
18.
By measurement of the conductance of various electrolytes in solutions of D-glucitol, D-glucose, glycerol, D-mannitol, and sucrose, the hydration of the polyhydroxy compounds and their association with electrolytes have been examined. The results have been analyzed in the light of conductance equations; it was found that D-glucose and sucrose associate with electrolytes, glycerol and D-mannitol are practically inert, and D-glucitol is only rarely bound. The association constants are of the order of 10?1 to 10?2. The results indicate that anions guide the process, with a free-energy change of 1.5–3.0 kcal.mole-1, the order of the energy of hydrogen bonding. In the analysis of conductance data, neglect of association may introduce hydration numbers many times greater than are usual.  相似文献   

19.
Giant deer or megacerines (tribe Megacerini, family Cervidae, order Artiodactyla) dwelt in Eurasia from the Late Miocene to Holocene and in Africa in the Late Pleistocene. Based on comparative morphological data and morphofunctional analysis, morphogenetic and ecogenetic trends in this group are improved. Classification, taxonomy, phylogeny, and geographical and stratigraphical ranges of megacerines are revised.  相似文献   

20.
K Kemp  G Danscher 《Histochemistry》1979,59(3):167-176
A technique for multi-element analysis of brain tissue by proton induced X-ray emission spectroscopy (PIXE) is described and data from analysis of fixed and unfixed samples from rat hippocampus, neocortex, amygdala, and spinal cord is presented and commented on. The atoms present in the tissue are bombarded with protons which causes the ejection of electrons from the inner shells. When the "holes" are refilled with electrons from outer shells, X-ray quanta characteristic for each element are emitted. Using a high resolution energy dispersive detector a complete X-ray spectrum of the specimen can be recorded in a single measurement. Detection limits less than or approximately 5 p.p.m. of dry matter are obtained for most elements with atomic number greater than 14 (silicon). Around 13 elements were found in concentrations above the detection limits. The grand means for non-fixed hippocampi were e.g. for Zn - 120 p.p.m.; Rb - 20 p.p.m.; Fe - 150 p.p.m.; Pb - 3 p.p.m; Ni - 5 p.p.m.  相似文献   

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