The mitochondrial genome. The nucleoid

Mitochondrial DNA (mtDNA) in cells is organized in nucleoids containing DNA and various proteins. This review discusses questions of organization and structural dynamics of nucleoids as well as their protein components. The structures of mt-nucleoid from different organisms are compared. The currently accepted model of nucleoid organization is described and questions needing answers for better understanding of the fine mechanisms of the mitochondrial genetic apparatus functioning are discussed.     

The Scalpel's Edge: The Culture of Surgeons

The Scalpel's Edge: The Culture of Surgeons. Pearl Katz. Needham Heights, MA: Allyn and Bacon, 1999. xii. 251 pp.     

The Seronera bull problem: The elephants

(1) The activities of bull elephants in the vicinity of the Serengeti National Park headquarters at Seronera was monitored from 1968 to 1971. (2) Elephant bulls congregate in small groups of ever–changing composition; a dominance heirarchy cuts across group integrity. (3) Occupancy of the drainage area of the Seronera river is predictable by rainfall; changes in occupancy level are a question of duration rather than amplitude. (4) The feeding behaviour of the bulls is described. It is argued that large Acacia trees are uprooted for nutritional rather than social reasons. The effects of the bulls on the Seronera woodlands will be analysed in Part II (Croze, 1974).     

The phyllosphere

Summary In connection with the as yet unexplained gains in nitrogen in young grassland, the phyllosphere of grasses, in particularTripsacum laxum Nash, has been studied on the experimental farm and in the laboratories of the ORSTOM (Organisation de Recherches Scientifiques Tropicales Outre-Mer) at Adiopodoumé (Ivory Coast, West Africa). Considerable concentrations of sugars were observed in rain water and dew (14–200 ppm) and in the stem run-off (up to 465 ppm). The values were exceeded by those of the moisture in the leaf sheaths (up to 10⁴ ppm), which thus form a special milieu for nitrogen-fixing elements. The composition of the microbial population depends on the physical state of the leaves concerned,viz age, climate, and weather conditions. The population consists mainly of Gram-negative rods, yeasts, and coryneform bacteria. The possible significance of the nitrogen fixation in grassland is discussed. The investigation is being continued in the Microbiological Laboratory at Wageningen.     

The claudins

The claudin multigene family encodes tetraspan membrane proteins that are crucial structural and functional components of tight junctions, which have important roles in regulating paracellular permeability and maintaining cell polarity in epithelial and endothelial cell sheets. In mammals, the claudin family consists of 24 members, which exhibit complex tissue-specific patterns of expression. The extracellular loops of claudins from adjacent cells interact with each other to seal the cellular sheet and regulate paracellular transport between the luminal and basolateral spaces. The claudins interact with multiple proteins and are intimately involved in signal transduction to and from the tight junction. Several claudin mouse knockout models have been generated and the diversity of phenotypes observed clearly demonstrates their important roles in the maintenance of tissue integrity in various organs. In addition, mutation of some claudin genes has been causatively associated with human diseases and claudin genes have been found to be deregulated in various cancers. The mechanisms of claudin regulation and their exact roles in normal physiology and disease are being elucidated, but much work remains to be done. The next several years are likely to witness an explosion in our understanding of these proteins, which may, in turn, provide new approaches for the targeted therapy of various diseases.     

The making of "The Genoma Music."

Both genetic and musical sequences are ordered structures composed of combinations of a small number of elements, of nucleotides and musical notes. In the case of the genome, the emergence of cellular functions makes the order meaningful; in the case of musical sequences, the consequence of order is the production of mysterious esthetical effects in the human mind. Can any musical significance be found in DNA sequence? In this work, we present the technique used to convert DNA sequences into musical sequences. The musical equivalent of the sequence of a number of genes, either of fungal origin, such as Candida albicans or Sacharomyces cerevisiae (SLT2), or belonging to the human genome (genes involved in Alzheimer syndrome, blindness, and deafness such as Connexine 26 gene) has been obtained. Non-coding sequences are also important in life and music. The non-coding alphoid sequence has also been translated into a musical sequence, in this case using Fibonacci golden number basic series as structural helper. The elementary musical sequence derived from DNA sequence has served as an imposing frame in which rhythms, sounds, and melodies have been harmonically inserted. The Genoma Music Project is essentially a creative metaphor of the basic unity between the human mind and the natural ordered structure of life.     

The first trees. The Archaeopteris model

The earliest self-supporting organisms exceeding 2 m in height evolved about 370 million years ago, approximately 100 million years after the rise of the first land plants. Evidence for the tree habit is usually indirect and assessed from the diameter of the available stem fragments. Four systematic groups of Devonian plants evolved the tree habit independantly: the Lycopsida, Cladoxylopsida, and progymnosperms in the Middle Devonian, the Equisetopsida in the Late Devonian. All share a free-sporing life cycle which limits their habitats to wet areas. Their branching pattern involves the strict division of their apices, whether equally or unequally. The progymnosperm genus Archaeopteris was widespread worldwide and evolved the highest trees of the Devonian (maximum height estimated at 40 m). Besides it ecological significance as the dominant component of the earliest forests, Archaeopteris currently represents the closest known relative to the seed plants with which it shares two derived characters, the heterosporous life cycle, and the possession of leaves. Another distinctive feature of Archaeopteris trees is represented by the double function of their wood for both support and conduction. New analyses involving vascular trace analysis in anatomically preserved specimens have demonstrated that Archaeopteris is not the simple tree reconstructed by Beck (1962). In this fate model, Archaeopteris consisted of an erect trunk bearing short-lived, flattened, leaf-like branch systems forming a terminal crown. New evidence indicates that laterally to these appendages of apical origin, a new type of branches, of adventitious origin, evolved which development compares to that of the axillary branches of the seed plants. These branches which were large and long-lived represent major architectural components of the tree. Evidence for vascular structures comparable to those produced on stem cuttings in modern plants suggest that Archaeopteris may have evolved vegetative strategies for propagation. The set of "modern" characters of Archaeopteris may explain its success until the Devonian/Carboniferous boundary when its extinction is correlated to the radiation of the earliest seed plants.     

中华眼镜蛇毒致局部组织损伤的动物实验研究

目的对中华眼镜蛇毒致局部组织损伤的6种治疗方法,通过动物实验进行疗效优劣比较,找出最佳治疗方法。方法用中华眼镜蛇毒制作动物家兔局部组织损伤模型,分别采用6种不同的治疗方法进行局部治疗,观察其疗效。结果6种治疗方法从优到劣依次是：抗蛇毒血清局部注射-糜蛋白酶局部注射-蛇伤药酒外敷-坏死组织早期切除-局部烧灼法-局部组织切开冲洗。结论中华眼镜蛇伤致局部组织损伤的治疗方法应首选抗蛇毒血清局部注射和糜蛋白酶局部注射,其次选用蛇伤药酒外敷．     

The road from The Microbial world to Microbe.

The year 2007 commemorates the 50th anniversary of the publication of The Microbial World, the seminal microbiology textbook that shattered the microbiology world and whose first edition was coauthored by Roger Y. Stanier, Michael Doudoroff and Edward A. Adelberg. The year 2007 marks also twenty-five years of Stanier's passing away. The Spanish Society for Microbiology (SEM) with the support of Fundación Ramón Areces has organized a Symposium, in the frame of the 21st national congress of the SEM (Seville, 17-20 September 2007), to commemorate those anniversaries, and has invited us (Schaechter, Ingraham and Neidhardt) to contribute to this celebration.     

The plague

The plague has been one of the most devastating diseases of human history. Despite major advances in diagnosis, prevention, and treatment, it has not been possible to eradicate this infection. Plague is still active in Africa, in Asia and in the Americas, and is classified as a currently re-emerging disease. The plague is mainly a disease of rodents, which is transmitted by fleabites. Humans develop two main clinical forms: bubonic plague (following bites of infected fleas, lethal in 50-70% of the cases in less than a week if an appropriate treatment is not started rapidly), and pneumonic plague (after inhalation of infected droplets, lethal in less than three days in 100% of cases without immediate treatment). Y. pestis, the causative agent of plague, is usually sensitive to most antibiotics, but the first multi-resistant strain was recently described. No efficient and safe vaccines are currently available. The plague bacillus is one of the few organisms that could be used for biological warfare.     

The GRID: The General Repository for Interaction Datasets

We have developed a relational database, called the General Repository for Interaction Datasets (The GRID) to archive and display physical, genetic and functional interactions. The GRID displays data-rich interaction tables for any protein of interest, combines literature-derived and high-throughput interaction datasets, and is readily accessible via the web. Interactions parsed in The GRID can be viewed in graphical form with a versatile visualization tool called Osprey.     

A型流感病毒非结构蛋白的功能及临床应用

NS1蛋白作为A型流感病毒的非结构蛋白,最初的研究着重于它对宿主细胞蛋白质合成的抑制作用方面考虑.随着研究的深入,对其基因的进化、蛋白质的抗原性作了详细的研究,同时发现流感病毒的NS1蛋白与流感病毒所诱导的细胞凋亡之间存在一定的联系,其对凋亡的调节作用与流感病毒感染的细胞是否产生干扰素及其所感染的细胞系直接相关.NS1蛋白能够抑制病毒感染细胞干扰素的产生,在流感病毒拮抗干扰素的抗病毒效应中发挥了重要的作用,许多研究表明,这种干扰素拮抗作用可能与流感病毒的毒力有关.由于传统疫苗的广泛应用,NS1蛋白在临床应用中作为鉴别诊断免疫禽和自然感染禽的检测抗原具有广阔的前景.     

The presenilins

The presenilins are evolutionarily conserved transmembrane proteins that regulate cleavage of certain other proteins in their transmembrane domains. The clinical significance of this regulation is shown by the contribution of presenilin mutations to 20-50% of early-onset cases of inherited Alzheimer's disease. Although the precise molecular mechanism underlying presenilin function or dysfunction remains elusive, presenilins are thought to be part of a complex of proteins that has 'γ-secretase cleavage' activity, which is clearly central in the pathogenesis of Alzheimer's disease. Mutations in presenilins increase the production of the longer isoforms of amyloid β peptide, which are neurotoxic and prone to self-aggregation. Biochemical studies indicate that the presenilins do not act alone but operate within large heteromeric protein complexes, whose components and enzymatic core are the subject of much study and controversy; one essential component is nicastrin. The presenilin primary sequence is remarkably well conserved in eukaryotes, suggesting some functional conservation; indeed, defects caused by mutations in the nemotode presenilin homolog can be rescued by human presenilin.     

The interleukins

The interactions between immune and inflammatory cells are mediated in large part by proteins, termed interleukins (IL), that are able to promote cell growth, differentiation, and functional activation. Seven interleukins have been described; each has unique biological activities as well as some that overlap with the others. Macrophages, cells that play important roles in both immunity and inflammation, produce IL 1 and IL 6, whereas T cells produce IL 2-IL 6 and bone marrow stromal cells produce IL 7. IL 1 and IL 6 not only play important roles in immune cell function, but also stimulate a spectrum of inflammatory cell types and induce fever. The growth and differentiation of eosinophils is markedly enhanced by IL 5. IL 2 is a potent proliferative signal for T cells, natural killer cells, and lymphokine-activated killer cells. IL 1, IL 3, IL 4, and IL 7 enhance the development of a variety of hematopoietic precursors. IL 4-IL 6 also serve to enhance B cell proliferation and antibody production. The understanding of interleukin structure and function has led to new and important insights into the fundamental biology of immunity and inflammation.     

The trophic state of shallow lakes in The Netherlands

A study has been carried out on the development of an ecological assessment method for shallow lakes in The Netherlands. Analyses of eutrophication characteristics of 93 lakes with, in total, 127 sampling localities gave insight into some of the steering variables, such as total-P, total-N, chlorophyll-a and transparency. On the basis of phytoplankton species composition, three main groups of lakes could be distinguished. The first group, characterized by persistent filamentous Cyanobacteria, had the highest summer means of chlorophyll-a and total-P. The second group was characterized by non-persistent filamentous Cyanobacteria, occurring in low abundancies, and at lower chlorophyll-a and total-P concentrations. The third group of lakes was characterized by the absence or very low abundance of the filamentous Cyanobacteria. As a result of these analyses, criteria for the abatement of eutrophication in shallow lakes could be refined.     

The RF-cinematogram

We present a spike-triggered averaging method capable of mapping the visual receptive fields of several neurons simultaneously. The stimulation is general and the mapping proceeds automatically without the need to match the stimulation to the cells' preference for position, orientation, direction, etc. The maps are spatiotemporal; receptive field (RF) structures are quantitatively determined in three dimensions: the two dimensions of visuotopic space, and time. The method presented is one of a family of reverse correlation or spike-triggered averaging techniques (DeBoer and Kuyper 1968) capable of revealing linear aspects of stimulus-response coupling. The formal relationship of these methods to stimulus-response crosscorrelation is shown. The analysis is extended to provide some second-order axis-of-motion information (direction marks). The stimulus is a constantly illuminated, randomly jumping bright or dark spot, not an elongated bar. Spot diameters between one-third to 1 × RF width are effective. The method ascertains for each recorded action potential or spike the prior visual field position of the spot. The average or most probable spot positions define the receptive field spatially. Repeating the process for a succession of times prior to observed spikes defines the field temporally, presented here as a succession of spatial maps. We term this portrayal a receptive field cinematogram, RFc or ciné. The RFc reveals and economically portrays the spread of excitability and suppression across the receptive field, culminating in the generation of a spike. RFcs for LGN neurons and for simple cells recorded in cat cortical areas 17 and 18 are presented and interpreted in terms of classic ON/OFF regions. The availability of temporal information permits the separation of an excitatory exit response, generated when a moving bright spot leaves an OFF region, from an excitatory entrance response occurring when a bright spot enters an ON region, because these responses occur at different times (exit responses earlier). Spike emission remains coupled to (cross-correlated with) stimulus events over time periods as long as 96 ms, implying that some stimulus drive or afferent visual input is delayed by as much as 96 ms more than other input. This is a striking instance of temporal dispersion in the visual system. In some cells, said to be spatiotemporally inseparable, the delay (latency) varies systematically across the visual field; i.e., the place for optimal stimulation varies with the time prior to spike emission. In these cells, the RFc shows receptive field structures which move across the visual field over trajectories equal to approximately twice the total conventional RF width. Exit and entrance responses, on the other hand, arise in a simple way from separated ON and OFF RF subregions. ON/ OFF mechanisms thus appear unrelated to spatiotemporal inseparability. The RFc method is easily automated, efficient, and characterizes multiple RFs simultaneously, as required in work with multiple electrode arrays.     

The Berbers

The Berbers. Michael Brett and Elizabeth Fentress. Cambridge, MA: Blackwell Publishers, 1996. 350 pp.     

The Archaeology Of The Breeden Site

Abstract

The Breeden Site cultural sequence reenforcesthe general culture history already established for the Bad-Cheyenne Region and the more inclusive Middle Missouri Tradition. House remains and the bulk of the ceramic materials from the site indicate habitation of the area by peoples of the Initial Middle Missouri Variant and the PostContact Coalescent Variant.Component A at the Breeden Site and the Monroe and Anderson components at the Dodd Site exhibit a complex of diagnosticcultural traits significant enough to define a new phase - the Anderson Phase. A temporal span of approximately A.D. 950to 1250 is suggested for the phase. Component B of the Breeden Site, an early manifestation of the Post-Contract Coalescent Variant, is closely associated with components of the Felicia Phase and the putative Talking Crow Phase. Breeden Component B probably represents an upriver movement of Coalescent peoples from the Big Bend area, eventually being assimilated into the Arikara populations of the Bad River Phase within the Bad-Cheyenne Region.     

The Philosophy of Education The Problem of Counteraction

The humanistic ideas of cooperative learning, which gained great popularity throughout the twentieth century, have had an enormous influence on the theory and practice of instruction and education. Instruction began to be considered not simply as the transmission and mastery of some particular cultural experience, but as a joint endeavor performed by actual or potential partners (the teachers and the students) directed at fostering the fullest and deepest possible social and personal development of each of the participants. The teacher's task was to help his pupils master, first and foremost, principles of mutual respect, good will, consideration of each other as individuals, how to reconcile differing needs, goals, and means of attaining them, and how to organize mutual aid, collaboration, and creative cooperation. All this was directed at the ultimate goal of instilling and realizing humanistic ideals in diverse areas of human culture.