北京地区蕨类植物区系分析

对北京地区蕨类植物区系进行了初步分析,研究表明,北京共有蕨类植物77种,隶属于19科34属,以蹄盖蕨科、岩蕨科、鳞毛蕨科、卷柏科等为优势科,以岩蕨属、卷柏属、铁角蕨属等为优势属,科内及属内分化程度较低,种类组成贫乏;地理成分以温带成分占优势,有11属为温带分布属,占非世界分布属总数的61．11％,除世界种和中国特有种外,全为温带性质的种;生境特点以石生为主,大多数种类分布在北京西部和北部的山区;与河北的关系最为密切,其次为山西、内蒙、辽宁、山东,与秦岭也有一定的联系,与西藏的关系疏远。     

北京市民营医疗机构发展现状与对策探析

描述了北京市民营医疗机构发展的基本情况及其特色优势,并从政策环境及自身建设两个方面分析了北京市民营医疗机构发展存在的主要问题,由此提出加快落实相关政策、优化民营医疗机构发展环境以及民营医疗机构加强自身建设和规范化管理等建议。     

Colicin Biology

Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology are presented: their synthesis, which is under SOS regulation; their release into the extracellular medium, which involves the colicin lysis protein; and their uptake mechanisms and modes of action. Colicins are organized into three domains, each one involved in a different step of the process of killing sensitive bacteria. The structures of some colicins are known at the atomic level and are discussed. Colicins exert their lethal action by first binding to specific receptors, which are outer membrane proteins used for the entry of specific nutrients. They are then translocated through the outer membrane and transit through the periplasm by either the Tol or the TonB system. The components of each system are known, and their implication in the functioning of the system is described. Colicins then reach their lethal target and act either by forming a voltage-dependent channel into the inner membrane or by using their endonuclease activity on DNA, rRNA, or tRNA. The mechanisms of inhibition by specific and cognate immunity proteins are presented. Finally, the use of colicins as laboratory or biotechnological tools and their mode of evolution are discussed.     

Colicin biology.

Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology are presented: their synthesis, which is under SOS regulation; their release into the extracellular medium, which involves the colicin lysis protein; and their uptake mechanisms and modes of action. Colicins are organized into three domains, each one involved in a different step of the process of killing sensitive bacteria. The structures of some colicins are known at the atomic level and are discussed. Colicins exert their lethal action by first binding to specific receptors, which are outer membrane proteins used for the entry of specific nutrients. They are then translocated through the outer membrane and transit through the periplasm by either the Tol or the TonB system. The components of each system are known, and their implication in the functioning of the system is described. Colicins then reach their lethal target and act either by forming a voltage-dependent channel into the inner membrane or by using their endonuclease activity on DNA, rRNA, or tRNA. The mechanisms of inhibition by specific and cognate immunity proteins are presented. Finally, the use of colicins as laboratory or biotechnological tools and their mode of evolution are discussed.     

Picking battles wisely: plant behaviour under competition

Plants are limited in their ability to choose their neighbours, but they are able to orchestrate a wide spectrum of rational competitive behaviours that increase their prospects to prevail under various ecological settings. Through the perception of neighbours, plants are able to anticipate probable competitive interactions and modify their competitive behaviours to maximize their long-term gains. Specifically, plants can minimize competitive encounters by avoiding their neighbours; maximize their competitive effects by aggressively confronting their neighbours; or tolerate the competitive effects of their neighbours. However, the adaptive values of these non-mutually exclusive options are expected to depend strongly on the plants' evolutionary background and to change dynamically according to their past development, and relative sizes and vigour. Additionally, the magnitude of competitive responsiveness is expected to be positively correlated with the reliability of the environmental information regarding the expected competitive interactions and the expected time left for further plastic modifications. Concurrent competition over external and internal resources and morphogenetic signals may enable some plants to increase their efficiency and external competitive performance by discriminately allocating limited resources to their more promising organs at the expense of failing or less successful organs.     

Propynylated phosphodiester oligonucleotides inhibit ICAM-1 expression in A549 cells on electroporation

Oligodeoxynucleotides (ODN) are used largely as either primers, antisense, or triplex-forming units. Phosphodiester ODN (PO-ODN), which are very rapidly degraded by exonucleases, must be protected at their ends. Even so, their life span inside cells is quite short. Phosphorothioate ODN (PS-ODN) are less sensitive to nucleases and are extensively used as antisense. Unfortunately, unlike PO-ODN, they interact with a number of molecules, including proteins, in addition to their specific nucleic acid targets. Their affinity for their target is lower than that of PO-ODN. PS-ODN containing propyne groups on C5 of pyrimidine have been shown to have a higher affinity toward their nucleic acid target. Here, we show that propynylated PO-ODN are more stable and much more efficient than their propyne-free counterparts. They are not efficient when they are used as lipoplexes, but they act as specific antisense on electroporation.     

Small,basic antifungal proteins secreted from filamentous ascomycetes: a comparative study regarding expression,structure, function and potential application

Peptides and proteins with antimicrobial activity are produced throughout all kingdoms in nature, from prokaryotes to lower and higher eukaryotes, including fungi, plants, invertebrates and vertebrates. These proteins contribute to an important constitutive or induced defense mechanism of the producer against microorganisms. According to their variety in structure and function, these proteins are classified arbitrarily into groups that are based on their mechanism of action, their structure and their similarity to other known proteins. The present review focuses on a new group of antimicrobial proteins, namely small, basic and cysteine-rich antifungal proteins, which are secreted from filamentous fungi of the group Ascomycetes. These proteins are encoded by orthologous genes and exhibit both similarities and differences concerning their species-specificity, primary structure, protein activity and target sites. The properties of these proteins, their possible mode of action and their potential application for human benefits are discussed in comparison with other already well known antimicrobial proteins.     

B chromosomes in plants: escapees from the A chromosome genome?

B chromosomes are dispensable elements that do not recombine with the A chromosomes of the regular complement and that follow their own evolutionary track. In some cases, they are known to be nuclear parasites with autonomous modes of inheritance, exploiting "drive" to ensure their survival in populations. Their "selfishness" brings them into conflict with their host nuclear genome and generates a host-parasite relationship, with anti-B-chromosome genes working to ameliorate the worst of their excesses in depriving their hosts of genetic resources. Molecular studies are homing in on their sequence organization to give us an insight into the origin and evolution of these enigmatic chromosomes, which are, with rare exceptions, without active genes.     

Acquired immunity to herbivory and allelopathy caused by airborne plant emissions

Numerous plant species respond to volatile cues to adjust their defenses against herbivores. Some volatile chemicals, such as terpenoids and green leaf volatiles, that are responsible for communication between plants and arthropods are also required for intraspecific communication between plants and for coordination among branches within a single plant. We are now aware that some ‘receiver’ plants are able to eavesdrop on their neighbors and tailor their defenses to their current and expected risks caused by herbivores. By contrast, a suite of volatiles also serve as natural herbicides (allelochemicals) that are detrimental for receiver plants. Since various molecular and ecological mechanisms underlying these phenomena have been clarified, it is time to ask whether more plants eavesdrop on infochemical cues, and if these cues that allow them to adjust their defenses to suit their risk also increase their fitness as a result.     

A test of Simpson's "rule of the survival of the relatively unspecialized" using fossil crinoids

Temporally long-ranging (=long-lived) taxa have been postulated to have unusual properties that aid their prolonged geologic survival. Past studies have examined dispersal capabilities, geographic ranges, and single-character morphological adaptations as factors that may contribute to geologic longevity. Here, I test whether long-lived fossil crinoid taxa are morphologically unusual using a whole suite of morphological characters. I define long-lived taxa in several explicit, comparative ways. I find that long-lived crinoid genera and families are often less distant from mean morphologies of their crinoid orders than their shorter-lived relatives; that is, they are relatively less specialized. I also compare the morphology of crinoid genera relative to basal members of their respective orders; mean morphological distances of long-lived genera from basal morphologies are seldom distinct from those of their shorter-lived relatives. I observe that long-lived crinoid genera are less distant from mean morphologies of their temporal cohorts compared with shorter-lived genera but not in a statistically significant manner. I conclude that long-lived crinoids are relatively unspecialized, in the sense that they are relatively closer to mean morphologies of their taxonomic groups.     

Snakin/GASA proteins: Involvement in hormone crosstalk and redox homeostasis

Snakin/GASA proteins are widely distributed among plant species. They are expressed in different plant organs with high tissue and temporal specificity, and their subcellular localization varies among the different members. Interestingly, all of them maintain 12 cysteines of the C-terminus in highly conserved positions of the aminoacid sequences that are essential for their biochemical activity and probably responsible for their protein structure. Despite their common features, their functions are not completely elucidated and little is known about their mode of action. This review focuses on the current knowledge about this intriguing family of peptides and advances comprising gene regulation analyses, expression pattern studies and phenotypic characterization of mutants and transgenic plants. Furthermore, we discuss the roles of Snakin/GASA proteins in several aspects of plant development, plant responses to biotic or abiotic stress and their participation in hormone crosstalk and redox homeostasis.     

Nutritional ecology of endoparasitic insects and their hosts: An overview

The impact of insect endoparasites (parasitoids) on the physiology and behaviour of their hosts is reviewed within the context of the nutritional ecology of the parasitoids and their hosts. Alterations in the consumption, utilization and allocation of food by parasitized hosts are common, as are internal changes in their metabolic physiology. Gregarious parasitoid species frequently increase feeding by their host larvae whereas solitary parasitoid species often reduce feeding and growth of their hosts. Many parasitoid-associated changes in host physiology and behaviour are interpreted to be of adaptive significance to parasitoids. Substantial circumstantial evidence suggests, and a few direct tests of such adaptive significance indicate, that parasitoids alter their hosts in ways beneficial to their own fitness. However, most of the changes in parasitized hosts are of unknown cause and undocumented significance to the parasitoids. Several relevant hypotheses are presented, and these require extensive evaluation (often requiring novel experimental approaches) before a thorough understanding of parasitoid nutritional ecology is established.     

Sex differences in the influence of mothers on the sociosexual preferences of their offspring

The extent to which "nurture" as opposed to "nature" determines behavior and sociosexual preferences in mammalian species is controversial although most recent interest has focused on genetic determinants. We report here that if sheep and goats are cross-fostered at birth, but raised in mixed-species groups, their play and grooming behavior resembles that of their foster rather than genetic species. There are no sex differences in effects on these behaviors, and other species-specific behavior patterns such as aggression, browsing, climbing, and vocalizations are unaffected. In adulthood, cross-fostered males strongly prefer to socialize and mate with females of their foster mother's species, even if raised with a conspecific of their own species. Castration within 2 days of birth slightly reduces the level of this altered social preference but mating preference following short-term testosterone treatment is the same as for gonadally intact animals. Cross-fostered females also show significant preference for socializing with females and mating with males of their foster mother's species, although this effect is weaker than that in both gonadally intact and castrated males. When cross-fostered animals are placed in flocks containing members of only their genetic species for 3 years, male social and mating preferences for females of their mother's species remain virtually unaffected. Females change to display an exclusive mating preference for members of their genetic species in 1-2 years although they still retain some social interest in female members of their foster species. Thus, there are clear sex differences in the impact of the emotional bond between a mother and her offspring in these mammals. Effects on males are strongest and irreversibly maintained even after altering their social environment, whereas those on females are weaker and mating preferences are clearly adaptable in the face of altered social priorities. These sex differences are presumably caused by pre-, or early postnatal, organizational effects of sex hormones on the brain.     

Cell wall alterations in staphylococci growing in situ in experimental osteomyelitis

When cells of both Staphylococcus aureus and Staphylococcus epidermidis are grown in batch culture in nutrient-rich media, their cell walls are regular in thickness, their cell size is within the normal range for each species, and their septation patterns are orderly. When cells of each of these species are examined directly in infected tissue in the rabbit tibia model infection, their cell wall thickness is often much increased and very irregular around the circumference of the cell, their cell size is often increased, and their septation patterns are often severely deranged. All of these alterations in cell wall structure occur in the absence of antibiotics, and we suggest that they may be an expression of phenotypic plasticity in response to altered environmental conditions such as specific nutrient limitations, the presence of antibacterial factors, and growth of the cells on hard surfaces such as rabbit bone or plastic catheters. Some of these specific cell wall alterations are also seen when staphylococcal cells are exposed, in vitro or in vivo, to antibiotics such as clindamycin, but we emphasize that growth in tissue alone is sufficient for their induction.     

Some relationships between the 'calling' posture and sexual receptivity in unmated females of the moth, Ephestia cautella

ABSTRACT. A positive relationship is shown between the frequency of successful completions of courtship and the extent of development of the 'calling' posture of E. cautella females. Further relationships are shown between the frequency of successful completions of courtship and the positions in which calling females hold their antennae. During late photophase, calling females which hold their antennae forward are less likely to mate than are similarly calling females which hold their antennae back over the wings, whereas in early scotophase this relationship is reversed, and calling females which hold their antennae forward are more likely to mate than are similarly calling females which hold their antennae back. These observations are discussed in relation to the diel rhythm of the species, disturbance, and female receptivity to male courtship.     

Book Reviews

Abstract

A study of the attitudes and actions of 281 dog owners towards neutering their animals is reported from New Providence, The Bahamas. Owner attitudes towards neutering are associated with different sterilization rates of dogs. While owners' gender is associated with differences in attitudes, these differences are not necessarily associated with owner behavior with respect to neutering their animals. Men, more than women, want to have animals for long-term breeding. No evidence is found to support the belief that men are less likely to neuter their dogs than women, but younger owners are less likely than older owners to neuter their dogs. A comparison with a study from Australia suggests that Bahamians are more likely to project human traits on to their animals and so appear more reluctant to have their dogs neutered.     

ERBB oncogene proteins as targets for monoclonal antibodies

General properties of the family of tyrosine kinase ERBB receptors are considered in connection with their role in the generation of cascades of signal transduction in normal and tumor cells. Causes of acquisition of oncogene features by genes encoding these receptors and their role in tumorigenesis are analyzed. Anti-ERBB monoclonal antibodies approved for therapy are described in detail, and mechanisms of their antitumor activity and development of resistance to them are reviewed. The existing and the most promising strategies for creating and using monoclonal antibodies and their derivatives for therapy of cancer are discussed.     

The effect of the phase transition on the hydration and electrical conductivity of phospholipids.

Adsorption isotherms for various saturated phosphatidylcholines have been obtained. Lipids above and below their phase transition temperature differ only in the amount of water adsorbed and not in the nature of their adsorption isotherms. Cholesterol has an effect similar to that of increasing unsaturation in the hydrocarbon chains. Decreasing the length of the hydrocarbon chains for lipids below their phase transition temperature has no effect on the isotherms. If the chain length is short enough so that the lipids are above their transition temperature, however, a large increase in water adsorption occurs. All of the phospholipids exhibit a rapid increase of electrical conductivity for a few water molecules adsorbed per lipid molecule. All of the phospholipids show a saturation in conductivity at greater amounts of adsorbed water; the shape of the saturation region depends on whether the lipids are above or below their phase transition temperature. The activation energy for the electrical conductivity process depends on whether the hydrated lipids are in the "liquid-like" of the crystalline state, being lower for phospholipids in the liquid-like state. If the lipids are hydrated above their phase transition temperatures, their activation energies are lower than if they are hydrated below the transition temperature. Cholesterol lowers the activation energy. The phosphatidylcholines can be characterized by different activation energies, depending both upon their physical state and the presence of unsaturation in their hydrocarbon chains.     

Characterization of homing endonucleases

Homing endonucleases are a class of site-specific DNA endonucleases encoded by open reading frames within introns and inteins. They initiate the mobility of their host element by recognizing intronless or inteinless alleles of their host gene and making a double-strand break. The homing endonucleases are notable for their long target sites and a tolerance for sequence polymorphisms in their substrates. The methods used to study homing endonucleases are similar to those used to study protein-DNA interactions in general. However, some variations and specialized techniques are useful in characterizing homing endonucleases and these methods are discussed.     

Can whole-drawer images measure up? A reply to Johnson et al. (2013)?

Johnson et al. (2013) found that morphometric measurements of dragonfly wings taken from actual specimens and measurements taken from whole-drawer images of those specimens were equally accurate. We do not believe that their conclusions are justified by their data and analysis. Our reasons are, first, that their study was constrained in ways that restrict the generalisability of their results, but second, and of far greater significance, their statistical approach was entirely unsuited to their data and their results misled them to erroneous conclusions. We offer an alternative analysis of their data as published. Our reanalysis demonstrates, contra Johnson et al., that measurements from scanned images are not a reliable substitute for direct measurement.