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1.
Truffles are the fruiting bodies of ascomycete fungi that form underground. Truffles are globally valued, culturally celebrated as aphrodisiacs, and highly sought-after delicacies in the culinary world. For centuries, naturalists have speculated about their mode of formation, and in cultures surrounding the Mediterranean Sea, many species have been prized as a delectable food source. Truffle fruiting bodies form underground and emit a variety of volatile organic compounds (VOCs). Truffle volatiles are believed to have evolved to attract animals that disperse their spores. The main VOCs identified from truffles include sulfur compounds, such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS); in addition, 1-octen-3-ol and 2-methyl-1-propanol have been found in most truffle species. Humans use pigs and dogs trained to detect truffle VOCs in order to find these prized subterranean macrofungi. Truffles have pharmacological potential, but until more reliable cultivation methods become available their high price means they are unlikely to see widespread use as medicinals.  相似文献   

2.
细菌和古菌等微生物与病毒(噬菌体)之间的生存之战是一场“军备竞赛”。细菌和古菌已经进化出多种先天和适应性的免疫系统来抵御噬菌体的入侵。噬菌体则利用不同的对抗策略来躲避这些噬菌体防御机制。CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-Associated)系统就是细菌和古菌广泛编码的一种抵御噬菌体等外源遗传元件的获得性免疫系统,与此同时,噬菌体也进化出特异性的anti-CRISPR来抵抗CRISPR-Cas系统的免疫。本文系统综述了anti-CRISPR的发现过程、分类和作用机制,并展望了其潜在的应用。  相似文献   

3.
A large proportion of the genes in any plant genome encode enzymes of primary and specialized (secondary) metabolism. Not all plant primary metabolites, those that are found in all or most species, have been identified. Moreover, only a small portion of the estimated hundreds of thousand specialized metabolites, those found only in restricted lineages, have been studied in any species. The correlative analysis of extensive metabolic profiling and gene expression profiling has proven a powerful approach for the identification of candidate genes and enzymes, particularly those in secondary metabolism. The final characterization of substrates, enzymatic activities, and products requires biochemical analysis, which has been most successful when candidate proteins have homology to other enzymes of known function. The challenges are to identify new types of enzymes and to develop biochemical techniques that are suitable for large-scale analysis.  相似文献   

4.
Microbes, warfare, religion, and human institutions   总被引:1,自引:0,他引:1  
A significant number of practicing microbiologists are not aware of the historical impact of infectious agents on the development of human institutions. Microbes have played a profound role in warfare, religion, migration of populations, art, and in diplomacy. Boundaries of nations have changed as a result of microbial diseases. Infectious agents have terminated some kingdoms and elevated others. There is a need for microbiologists to have a historical perspective of some of the major ways in which a pathogen may influence civilized populations. Conditions may exist in contemporary society for a repeat of some of the kinds of plagues suffered by previous societies. The purpose of this paper is to review examples of situations where pathogenic microbes have forced societal modifications on centers of human population.  相似文献   

5.
Macrolides have enjoyed a resurgence as new derivatives and related compounds have come to market. These newer compounds have become important in the treatment of community-acquired pneumoniae and nontuberculosis-Mycobacterium diseases. In this review, the bacterial mechanisms of resistance to the macrolide, lincosamide, streptogramin, ketolide, and oxazolidinone antibiotics, the distribution of the various acquired genes that confer resistance, as well as mutations that have been identified in clinical and laboratory strains are examined.  相似文献   

6.
Gastric cancer still represents a global health care burden, and in the absence of strategies implemented for early detection, the disease continues to have a dismal prognosis. Patients presenting with clinical manifestations of gastric cancer have limited options for cure. Thus, early detection and prevention play a key role in the fight against gastric cancer. Serologic-based test methods have the potential to detect a subset of patients at high risk of gastric cancer that require a close clinical and endoscopic follow-up. More data have been produced to support Helicobacter pylori eradication as an efficient strategy to prevent gastric cancer. Treatment options for patients with an advanced disease are still limited, but the introduction of new agents opens a more optimistic perspective for the future.  相似文献   

7.
The structure, function, and mechanism of action of plant calmodulins have been the subject of intense study for plant scientists during the past several years. While precedents in animal biochemistry and physiology have suggested logical starting points for studies of how calmodulin is involved in higher plant and algal cell function, recent biochemical studies have demonstrated unique structural characteristics for this highly conserved protein. Enzym‐ological analyses have demonstrated novel functional properties and provided limited insight into the molecular mechanisms of calmodulin action. This review will summarize much of the early work, but will concern itself mainly with the methods and approaches that are used to study plant and animal calmodulins as well as models for how calmodulin may be involved in plant cell function.  相似文献   

8.
Investigators of animal behavior since the eighteenth century have sought to make their work integral to the enterprises of natural history and/or the life sciences. In their efforts to do so, they have frequently based their claims of authority on the advantages offered by the special places where they have conducted their research. The zoo, the laboratory, and the field have been major settings for animal behavior studies. The issue of the relative advantages of these different sites has been a persistent one in the history of animal behavior studies up to and including the work of the ethologists of the twentieth century. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

9.
MTs are small cysteine-rich metal-binding proteins found in many species and, although there are differences between them, it is of note that they have a great deal of sequence and structural homology. Mammalian MTs are 61 or 62 amino acid polypep-tides containing 20 conserved cysteine residues that underpin the binding of metals. The existence of MT across species is indicative of its biological demand, while the conservation of cysteines indicates that these are undoubtedly central to the function of this protein. Four MT isoforms have been found so far, MT-1, MT-2, MT-3, and MT-4, but these also have subtypes with 17 MT genes identified in man, of which 10 are known to be functional. Different cells express different MT isoforms with varying levels of expression perhaps as a result of the different function of each isoform. Even different metals induce and bind to MTs to different extents. Over 40 years of research into MT have yielded much information on this protein, but have failed to assign to it a definitive biological role. The fact that multiple MT isoforms exist, and the great variety of substances and agents that act as inducers, further complicates the search for the biological role of MTs. This article reviews the current knowledge on the biochemistry, induction, regulation, and degradation of this protein in mammals, with a particular emphasis on human MTs. It also considers the possible biological roles of this protein, which include participation in cell proliferation and apoptosis, homeostasis of essential metals, cellular free radical scavenging, and metal detoxification.  相似文献   

10.
MTs are small cysteine-rich metal-binding proteins found in many species and, although there are differences between them, it is of note that they have a great deal of sequence and structural homology. Mammalian MTs are 61 or 62 amino acid polypeptides containing 20 conserved cysteine residues that underpin the binding of metals. The existence of MT across species is indicative of its biological demand, while the conservation of cysteines indicates that these are undoubtedly central to the function of this protein. Four MT isoforms have been found so far, MT-1, MT-2, MT-3, and MT-4, but these also have subtypes with 17 MT genes identified in man, of which 10 are known to be functional. Different cells express different MT isoforms with varying levels of expression perhaps as a result of the different function of each isoform. Even different metals induce and bind to MTs to different extents. Over 40 years of research into MT have yielded much information on this protein, but have failed to assign to it a definitive biological role. The fact that multiple MT isoforms exist, and the great variety of substances and agents that act as inducers, further complicates the search for the biological role of MTs. This article reviews the current knowledge on the biochemistry, induction, regulation, and degradation of this protein in mammals, with a particular emphasis on human MTs. It also considers the possible biological roles of this protein, which include participation in cell proliferation and apoptosis, homeostasis of essential metals, cellular free radical scavenging, and metal detoxification.  相似文献   

11.
The copper(II) complexes with ciprofloxacin (CFLH), levofloxacin (LFLH), norfloxacin (NFLH), and neutral bidentate ligands have been synthesized and characterized. The complexes have been evaluated for their antibacterial activity against selective species. Complexes have been also checked for their interacting behavior with DNA, and were found to have two different modes of interaction, classical and partial intercalation. Tested complexes were found to be better antioxidants with their IC50 values ranging from 0.51 to 0.97 μM.  相似文献   

12.
Iron, infection, and neoplasia   总被引:6,自引:0,他引:6  
In nearly all forms of life, the number and diversity of enzymes that contain iron or that depend on the presence of this metal for activity are impressive. Not surprisingly, chemical mechanisms have been evolved by many organisms that permit them to solubilize and acquire iron while at the same time depriving their competitors or their pathogens of this element. Proteins such as transferrin and lactoferrin that are employed by vertebrate hosts for iron transport and acquisition can, to some extent, withhold the metal from the siderophores of invading bacteria and fungi. Attempts also are made by animal hosts to withhold iron from protozoa and neoplastic cells. Unfortunately, pathogenic microorganisms have developed a variety of counter measures that are especially dangerous in hosts stressed by iron overload in specific fluids, tissues, or cells. In recent years, however, a number of possible methods and agents for strengthening iron-withholding defense have become apparent. Nearly 3,000 papers on various aspects of iron withholding are contained in the 18-year Medline Database and numerous reviews have been published since 1966. The present paper will focus on developments that have been reported within the past 2 1/2 years.  相似文献   

13.
Although adult Lepidoptera are not often considered medically relevant, some butterflies and moths are notorious for their consumption of mammalian body fluids. These Lepidoptera can be blood‐feeding (hematophagous), tear‐feeding (lachryphagous), or sweat‐feeding (we use the term “sudophagous”). Blood‐feeding Lepidoptera have been observed piercing the skin of their hosts during feeding, while tear‐feeding Lepidoptera have been observed frequenting the eyes of hosts in order to directly obtain lachrymal fluid. These behaviors have negative human health implications and some potential for disease transmission. In this study, articles concerning feeding behavior of blood, sweat, and tear‐feeding Lepidoptera were reviewed, with emphasis on correlations between morphological characters and feeding behaviors. Harmful effects and vector potential of these Lepidoptera are presented and discussed.  相似文献   

14.
Invertebrate animals have long played an important role in biomedical research in such fields as genetics, physiology, and development. However, with few exceptions, scientists, veterinarians, and technicians have paid little attention to the anesthesia, analgesia, and euthanasia of these diverse creatures. Indeed, some standard research procedures are routinely performed without anesthesia. Yet various chemical agents are available for the immobilization or anesthesia of invertebrates, ranging from gases or volatile liquids that can be pumped into either an anesthetic chamber (for terrestrial species) or a container of water (aquatic species), to benzocaine and other substances for fish. Many invertebrates are not difficult to immobilize or anesthetize and the procedures recommended in this article appear to be safe; however, none should be considered totally risk-free. Analgesia of invertebrates is as yet a largely unexplored field; until scientific data are available, other measures can promote the well-being of these animals in the laboratory. For euthanasia, various methods (physical or chemical or a combination of both) have been recommended for different taxa of invertebrates, but most have not been properly studied under laboratory conditions and some can be problematic in the context of research procedures and tissue harvesting. Furthermore, relevant data are scattered, sometimes available only in languages other than English, and there is no international approach for seeking and collating such information. In this article I review various methods of anesthesia, analgesia, and euthanasia for terrestrial and aquatic invertebrates, as well as areas requiring further research.  相似文献   

15.
13C-N.m.r. spectroscopy has been used to determine the equilibrium composition of solutions of maltulose and isomaltulose in deuterium oxide. Resonance assignments have been made for maltulose, isomaltulose, sucrose, leucrose, 1-kestose, nystose, inulin, and grass levan. Some earlier assignments for sucrose and grass levan are corrected. The resonances of the D-glucopyranosyl group in maltulose and isomaltulose have been observed to be sensitive to the ring and anomeric forms of the adjacent D-fructose residue. Spin-lattice relaxation-times (T1) and nuclear Overhauser enhancement factors (n.O.e.f.) for the carbon atoms of the D-fructofuranosyl residues of inulin have been measured, and used in conjunction with deuteration, to aid in resonance and linkage assignments.  相似文献   

16.
A new series of macrocyclic complexes of type [M(TML)X]X2, where M = Cr(III), Mn(III), or Fe(III), TML is tetradentate macrocyclic ligand, and X = Cl?, NO3?, CH3COO? for Cr(III), Fe(III) and X = CH3COO? for Mn (III), has been synthesized by condensation of benzil and succinyldihydrazide in the presence of metal salt. The complexes have been so formulated due to the 1:2 electrolytic nature of these complexes as shown by conductivity measurements. The complexes have been characterized with the help of various physicochemical techniques such as elemental analysis, molar conductance, electronic and infrared spectral studies, and magnetic susceptibility. On the basis of these studies, a five-coordinate distorted square pyramidal geometry, in which two nitrogens and two carbonyl oxygen atoms are suitably placed for coordination toward the metal ion, has been proposed for all the complexes. The complexes have been tested for their in vitro antibacterial activity. Some of the complexes show remarkable antibacterial activities against some selected bacterial strains. The minimum inhibitory concentrations shown by these complexes have been compared with those shown by some standard antibiotics such as linezolid and cefaclor.  相似文献   

17.
Antifreeze proteins (AFPs) are a group of proteins that protect organisms from deep freezing temperatures and are expressed in vertebrates, invertebrates, plants, bacteria, and fungi. The nuclear magnetic resonance, x-ray structure, and many spectroscopic studies with AFPs have been instrumental in determining the structure–function relationship. Mutational studies have indicated the importance of hydrophobic residues in ice binding. Various studies have pointed out that the mechanism of AFP action is through its adsorption on the ice surface, which leads to a curved surface, preventing further growth of ice by the “Kelvin effect.” The AFPs have potential industrial, medical, and agricultural application in different fields, such as food technology, preservation of cell lines, organs, cryosurgery, and cold hardy transgenic plants and animals. However, the applications of AFPs are marred by high cost due to low yield. This review deals with the source and properties of AFPs from an angle of their application and their potential. The possibility of production using different molecular biological techniques, which will help increase the yield, is also dealt with.  相似文献   

18.
Antifreeze proteins (AFPs) are a group of proteins that protect organisms from deep freezing temperatures and are expressed in vertebrates, invertebrates, plants, bacteria, and fungi. The nuclear magnetic resonance, x-ray structure, and many spectroscopic studies with AFPs have been instrumental in determining the structure-function relationship. Mutational studies have indicated the importance of hydrophobic residues in ice binding. Various studies have pointed out that the mechanism of AFP action is through its adsorption on the ice surface, which leads to a curved surface, preventing further growth of ice by the "Kelvin effect." The AFPs have potential industrial, medical, and agricultural application in different fields, such as food technology, preservation of cell lines, organs, cryosurgery, and cold hardy transgenic plants and animals. However, the applications of AFPs are marred by high cost due to low yield. This review deals with the source and properties of AFPs from an angle of their application and their potential. The possibility of production using different molecular biological techniques, which will help increase the yield, is also dealt with.  相似文献   

19.
Gold monodispersed nanoparticles (smaller than 10 nm) have been embedded into sepiolite fibres and sintered by spark plasma sintering (SPS) in order to preserve their nanometre size. The optical properties of these nanoparticles have been measured showing the surface plasmon resonance. Plasmon absorption curves have been successfully fitted by using the quasistatic approximation for gold nanoparticles. It has been observed that the sintering process decreases the plasmon width. SPS sintered nanostructured compacts present large values of the non-linear third-order dielectric susceptibility related to the gold concentration.  相似文献   

20.
44 patients suffering from myelomonocytic leukemia (MML) have been observed over the last four years. They have been subclassified in acute myelomonocytic and acute monoblastic leukemias (AMML, n = 12; AMoL, n = 10), subacute myelomonocytic leukemias (SMML, n = 13), and chronic myelomonocytic leukemias (CMML, n = 9) on the basis of bone marrow cytology(blast and promonocyte counts, maturation of granulopoesis) and cytochemical findings (peroxydase and unspecific esterase reaction). This subclassification has been proved to be of prognostic relevance by its good correlation with the mean survival times (AMML : 4.5 months, AMoL : 2.4 months, SMML : 8 months, CMML : 18 months). The acute forms have been treated in general with combined cytostatic chemotherapy, whereas SMML and CMML have been treated this way only in case of progression to an acute phase. These progressions to an AMML have been observed more often and earlier in subacute forms than in chronic forms. The diagnosis of SMML and CMML is supported by the finding of sea-blue histiocytes in the bone marrow, increased lysozyme levels in serum and urine and by the absence of the Philadelphia-Chromosome.  相似文献   

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