The contribution of plant biology to the concept of virus (1886-1917).

Between 1860 and 1880 the so-called "theory of the infective germ", which stated in final way that every infectious disease was produced by a living pathogen agent, achieved great consent. The criteria of determining the presence of infectious pathogens (fungi, bacteria, protozoa) were established by "Koch's postulate", a set of experimental procedures conceived for isolating and determining single pathogens. In the last quarter of the 19th century became however evident that the agents of severe infectious diseases could not be identified through the "postulates". These agents could not be seen in light microscopy nor cultured in vitro but could pass through the thin pores of filters which hold back cellular micro-organisms. This last characteristic became a selective method to recognise these peculiar agents, from then named "filterable viruses". Most microbiologists considered the filterable viruses as living micro-organisms because of their extraordinary capacity of in vivo proliferation, and the impossibility of pointing out their structures was due to limits of the experimental techniques. Between the end of the 19th century and 1917, four plant biologists suggested that the filterable viruses were complex chemical substances rather than cellular microorganisms. Their contribution, not appreciated by the contemporary colleagues, laid the foundation of the modern concept of virus.     

The contribution of the Nobel laureates to biochemistry and molecular biology

The Nobel Prize winners works are considered and analyzed. Main attention is paid to the works devoted to biochemistry or problems related to biochemistry. The most prominent biochemical investigations are considered in detail. In some cases it is given the history and chronology of important biochemical discoveries. The survey is devoted due to the 170th anniversary of birth of Alfred Bernhard Nobel--a famous scientist and businessman, the founder of the Nobel Prizes.     

Study of developmental homeostasis: From population developmental biology and the health of environment concept to the sustainable development concept

The study of the indices of developmental homeostasis in natural populations leads to the definition of the fundamentals of population developmental biology, which is associated with the assessment of the nature of phenotypic diversity and the mechanisms of population dynamics and microevolutionary changes. Characterization of environmental quality based on the assessment of population status by developmental homeostasis determines the fundamentals of the health of environment concept. The use of the ideas of developmental homeostasis and the health of environment in the studies of homeostatic mechanisms of biological systems of different levels (from the organism and population to the community and ecosystem) is promising. This gives new opportunities for understanding the mechanisms that provide sustainability and their ratio at different levels as well as for the characterization of ontogenetic stability significance. The notion of developmental homeostasis, or homeorhesis, is promising for the elaboration of the ecological and biological basics of sustainable development.     

Distribution of ultramicrobacteria in a gulf coast estuary and induction of ultramicrobacteria

The abundance of ultramicrobacteria (i.e., bacteria that pass through a 0.2m filter) in a subtropical Alabama estuary was determined during a 1-year period. Although phenotypic and molecular characterization indicated that the population of ultramicrobacteria was dominated byVibrio species, species ofListonella andPseudomonas were also abundant. Vibrios occurred with the greatest frequency in waters whose salinities were less than 14, and were the most abundant species of the total ultramicrobacterial population year-round, whilePseudomonas species were absent or considerably reduced during the winter months. The total number of ultramicrobacteria showed an inverse relationship to total heterotrophic bacteria as measured by colony-forming units (CFU)/ml and to water quality as measured by several parameters. Analysis by generic composition indicated that both salinity and temperature significantly affected the distribution of these organisms. Laboratory studies revealed that strains of vibrios under starvation in both static and continuous-flow microcosms could be induced to form cells that passed through 0.2 and/or 0.4m filters. Cells exposed to low nutrients became very small; some grew on both oligotrophic (5.5 mg carbon/liter) and eutrophic (5.5 g carbon/liter) media; and some few cells grew only on oligotrophic media. By passing selected vibrio strains on progressively diluted nutrient media, cells were also obtained that were small, that passed through 0.4m filters, and that could grow in oligotrophic media. These results suggest that ultramicrobacteria in estuaries (at least some portion of the population) may be nutrientstarved or low nutrient-induced forms of certain heterotrophic, eutrophic, autochthonous, estuarine bacteria.     

The contribution of statistical physics to evolutionary biology

Evolutionary biology shares many concepts with statistical physics: both deal with populations, whether of molecules or organisms, and both seek to simplify evolution in very many dimensions. Often, methodologies have undergone parallel and independent development, as with stochastic methods in population genetics. Here, we discuss aspects of population genetics that have embraced methods from physics: non-equilibrium statistical mechanics, travelling waves and Monte-Carlo methods, among others, have been used to study polygenic evolution, rates of adaptation and range expansions. These applications indicate that evolutionary biology can further benefit from interactions with other areas of statistical physics; for example, by following the distribution of paths taken by a population through time.     

The contribution of invertebrate study to the biology of nitric oxide

After the identification of nitric oxide (NO) with the endothelium derived-relaxing factor, many signaling mechanisms involving NO were identified through experiments on Mammals. NO activates soluble guanylyl cyclase leading to the formation of cGMP, stimulates the ADP-ribosylation of GAPDH, altering the cell energy production and combines with superoxide, generating cytotoxic peroxynitrite. NO was then progressively established as a major messenger molecule in Mammals. It is implied in the regulation of blood vessel dilatation, immune function, development and neurotransmission in brain and peripheral nervous system. Later, parallel findings were observed in Invertebrates and then, NO appeared as a signaling molecule widely spread throughout the animal kingdom and whose functions were highly conserved during evolution. The purpose of this short review is to highlight the contribution of Invertebrate studies to the knowledge of NO biology.     

A contribution to the mathematical biology of social behavior: Riots by oppressed groups

The author’s theory of imitation or mass behavior (N. Rashevsky:Mathematical Biology of Social Behavior, chapter xii, revised edition. Chicago: The University of Chicago Press, 1959; also Rashevsky:Looking at History through Mathematics, Cambridge, Mass.: The MIT Pres, 1968), when society chooses one of two mutually exclusive behaviors, is applied to the interaction of two social groups, an oppressor group and an oppressed one. Using crude approximations, conditions are derived as to when the oppressed group will revolt or riot, when the revolt will be suppressed, and when the oppressors will completely give in and oppression will end. Even in the simple approximation used, the situation depends on 14 parameters showing that a simplistic view on riots such as mere strong punishments is utterly inadequate. It is also shown that situations may exist in which revolution-like changes from one type of behavior of a society to another cannot be prevented by any measures.     

生物学概念的教学研究

对生物学概念的含义、类型、获得方式（概念同化,概念形成）进行了研究,并在此基础上提出了概念教学的基本策略。     

A contribution to the mathematical biology of the rates of historical development

The paper is a second step toward a biomathematical theory of the rates of spread of new nonconformist ideas or behaviors in a society. It is intended as a preliminary and purely theoretical study of a very oversimplified case. An equation which determines the distribution function of the tendencies toward conformist and nonconformist behaviors is set up under a number of oversimplified assumptions, and a solution by successive approximations is indicated. The expression for the first approximation is given, and an estimate of the order of magnitude of the rates of changes is made. In conclusion an outline is given for further improvement of the theory.     

A contribution to the search of general mathematical principles in biology

A somewhat different approach to the principle of biotopological mapping, discussed in previous publications, is given. The organism is considered as a set of properties, each of which is in its turn a set of numerous subproperties which are logically included in the corresponding properties. Topology is introduced by an appropriate definition of neighborhoods, and four postulates are stated which concern the mapping of the spaces corresponding to higher organisms on those of lower ones. A number of conclusions are drawn from the postulates. Some of them correspond to well-known facts. For example, in man and some higher organisms appropriate emotional stimuli should produce gastrointestinal or cardiovascular disturbances; or some microorganisms should produce substances harmful to other microorganisms (antibiotics). Some other conclusions are still awaiting verification. One of them is, for example, that there must exist unicellular organisms which produce antibodies to appropriate antigens.     

Systems biology of eukaryotic superorganisms and the holobiont concept

The founders of modern biology (Jean Lamarck, Charles Darwin, August Weismann etc.) were organismic life scientists who attempted to understand the morphology and evolution of living beings as a whole (i.e., the phenotype). However, with the emergence of the study of animal and plant physiology in the nineteenth century, this “holistic view” of the living world changed and was ultimately replaced by a reductionistic perspective. Here, I summarize the history of systems biology, i.e., the modern approach to understand living beings as integrative organisms, from genotype to phenotype. It is documented that the physiologists Claude Bernard and Julius Sachs, who studied humans and plants, respectively, were early pioneers of this discipline, which was formally founded 50 years ago. In 1968, two influential monographs, authored by Ludwig von Bertalanffy and Mihajlo D. Mesarovi?, were published, wherein a “systems theory of biology” was outlined. Definitions of systems biology are presented with reference to metabolic or cell signaling networks, analyzed via genomics, proteomics, and other methods, combined with computer simulations/mathematical modeling. Then, key insights of this discipline with respect to epiphytic microbes (Methylobacterium sp.) and simple bacteria (Mycoplasma sp.) are described. The principles of homeostasis, molecular systems energetics, gnotobiology, and holobionts (i.e., complexities of host–microbiota interactions) are outlined, and the significance of systems biology for evolutionary theories is addressed. Based on the microbe—Homo sapiens—symbiosis, it is concluded that human biology and health should be interpreted in light of a view of the biomedical sciences that is based on the holobiont concept.     

生物学概念教学策略初探

生物学概念的教学是生物学教学的一项重要任务。在具体的生物学概念教学实践中,教师采用的教学策略风格各异,但就其共性来说,生物学概念的教学策略一般由五个层次性的环节组成。本文就这五个萃知理论,结合教学实践作一些探讨。     

The contribution of dormant origins to genome stability: From cell biology to human genetics

The ability of a eukaryotic cell to precisely and accurately replicate its DNA is crucial to maintain genome stability. Here we describe our current understanding of the process by which origins are licensed for DNA replication and review recent work suggesting that fork stalling has exerted a strong selective pressure on the positioning of licensed origins. In light of this, we discuss the complex and disparate phenotypes observed in mouse models and humans patients that arise due to defects in replication licensing proteins.     

Editorial and introduction: The species concept in fish biology

Reviews in Fish Biology and Fisheries -     

The concept of mechanism in biology

The concept of mechanism in biology has three distinct meanings. It may refer to a philosophical thesis about the nature of life and biology ('mechanicism'), to the internal workings of a machine-like structure ('machine mechanism'), or to the causal explanation of a particular phenomenon ('causal mechanism'). In this paper I trace the conceptual evolution of 'mechanism' in the history of biology, and I examine how the three meanings of this term have come to be featured in the philosophy of biology, situating the new 'mechanismic program' in this context. I argue that the leading advocates of the mechanismic program (i.e., Craver, Darden, Bechtel, etc.) inadvertently conflate the different senses of 'mechanism'. Specifically, they all inappropriately endow causal mechanisms with the ontic status of machine mechanisms, and this invariably results in problematic accounts of the role played by mechanism-talk in scientific practice. I suggest that for effective analyses of the concept of mechanism, causal mechanisms need to be distinguished from machine mechanisms, and the new mechanismic program in the philosophy of biology needs to be demarcated from the traditional concerns of mechanistic biology.