Green's functions in biological potential problems

Electrical potential problems encountered in biology differ from those usually considered in electrical theory first, because the membranes of tissues satisfy a non-linear relation between current flow and polarization, and second, because the interior of the tissues are not equipotentials. A Green's function suitable for discussing such problems is defined, and a cylindrical illustration of such a function is discussed.     

Errors drive the evolution of biological signalling to costly codes

Reduction of costs in biological signalling seems an evolutionary advantage, but recent experiments have shown signalling codes shifted to signals of high cost with an underutilization of low-cost signals. Here I derive a theory for efficient signalling that includes both errors and costs as constraints and I show that errors in the efficient translation of biological states into signals can shift codes to higher costs, effectively performing a quality control. The statistical structure of signal usage is predicted to be of a generalized Boltzmann form that penalizes signals that are costly and sensitive to errors. This predicted distribution of signal usage against signal cost has two main features: an exponential tail required for cost efficiency and an underutilization of the low-cost signals required to protect the signalling quality from the errors. These predictions are shown to correspond quantitatively to the experiments in which gathering signal statistics is feasible as in visual cortex neurons.     

Biological problems of origin and development of various physiological functions (theory and application)

The author presents some idea about origin and development of some physiological functions: outer breathing, breath function of blood, blood circulation, thermoregulation, energy supply. The conclusions about main directions of evolution of these functions and duration of their development in phylogeny were drawn. The author gave some examples of abrupt changes of development of these functions in different groups of animals and discussed possible reasons of such changes. General quantitative estimation of the results of evolution of these functions from the position of their summArized efficiency was done. Quantitative characteristics of optimization and efficiency limits of physiological functions were suggested on the base of new data in general biology and comparative physiology. The author put toward the hypothesis about conventional "mistakes" of evolution and showed deep biological reasons of some seriOus illness. The examples of some applied problems in biology, physiology and medicine that can be solved with the data on evolution of physiological functions are presented.     

Current studies on physiological functions and biological production of lactosucrose

Lactosucrose (O-β-d-galactopyranosyl-(1,4)-O-α-d-glucopyranosyl-(1,2)-β-d-fructofuranoside) is a trisaccharide formed from lactose and sucrose by enzymatic transglycosylation. This rare trisaccharide is a kind of indigestible carbohydrate, has good prebiotic effect, and promotes intestinal mineral absorption. It has been used as a functional ingredient in a range of food products which are approved as foods for specified health uses in Japan. Using lactose and sucrose as substrates, lactosucrose can be produced through transfructosylation by β-fructofuranosidase from Arthrobacter sp. K-1 or a range of levansucrases, or through transgalactosylation by β-galactosidase from Bacillus circulans. This article presented a review of recent studies on the physiological functions of lactosucrose and the biological production from lactose and sucrose by different enzymes.     

Ageing and physiological functions.

In youth, most physiological functions have generous spare capacity. Even in health, however, increasing age is characterized by progressive erosion of these ''safety margins''. Examples include the decline of bone mass (towards a threshold for likelihood of fracture), of glomerular filtration rate (towards a threshold for susceptibility to clinical renal failure), of renal tubular function (towards a threshold for clinically important susceptibility to dehydration), of hepatic function (towards a threshold for accumulation following conventional ''young adult'' doses of common medications), or of lower limb explosive power (towards thresholds for impaired functional mobility). Increasing age is also characterized by a rising prevalence of chronic pathologies, complicating attempts to determine the rate or the mechanism of the age-related decline in a physiological function. Nevertheless, it is clear that in many organs the loss of function is largely attributable to the loss of functioning cells, even in the absence of overt disease. This apparently fundamental aspect of ageing remains poorly understood.     

Beetle elytra: evolution,modifications and biological functions

Conversion of forewings into hardened covers, elytra, was a ground-breaking morphological adaptation that has contributed to the extraordinary evolutionary success of beetles. Nevertheless, the knowledge of the functional aspects of these structures is still fragmentary and scattered across a large number of studies. Here, we have synthesized the presently available information on the evolution, development, modifications and biological functions of this crucial evolutionary novelty. The formation of elytra took place in the earliest evolution of Coleoptera, very likely already in the Carboniferous, and was achieved through the gradual process of progressive forewing sclerotization and the formation of inward directed epipleura and a secluded sub-elytral space. In many lineages of modern beetles, the elytra have been distinctly modified. This includes multiple surface modifications, a rigid connection or fusion of the elytra, or partial or complete reduction. Beetle elytra can be involved in a very broad spectrum of functions: mechanical protection of hind wings and body, anti-predator strategies, thermoregulation and water saving, water harvesting, flight, hind wing folding, diving and swimming, self-cleaning and burrow cleaning, phoresy of symbiotic organisms, mating and courtship, and acoustic communication. We postulate that the potential of the elytra to take over multiple tasks has enormously contributed to the unparalleled diversification of beetles.     

Second nature: biological functions of the Raf-1 "kinase"

More than 20 years ago, Raf was discovered as a cellular oncogene transduced by transforming retroviruses. Since then, the three Raf isoforms have been intensively studied, mainly as the kinases linking Ras to the MEK/ERK signaling module. As this pathway is activated in human cancer, the Raf kinases are considered promising therapeutic targets, and we have learned a lot about their regulation, targets, and functions. Do they still hold surprises? Recent gene targeting studies indicate that they do. This review focuses on the regulation and biology of the best-studied Raf isoform, Raf-1, in the context of its kinase-independent functions.     

Physiological functions of hydroperoxidases in Rhodobacter capsulatus.

Rhodobacter capsulatus J1 has two hydroperoxidases: a catalase-peroxidase and a peroxidase. A mutant strain, AH18, that had no catalase-peroxidase was isolated. The growth rate under aerobic and photosynthetic conditions, respiration, superoxide dismutase and peroxidase activities, and pigment content of the mutant were similar to those of the wild type. AH18 was more susceptible to killing and to inhibition of nitrogenase by H2O2 but not by molecular oxygen. The incidences of spontaneous mutations were similar in both strains. Viable counts in aerobic but not anaerobic cultures of AH18 started to decline as soon as the cultures reached the stationary phase, and the rate of cell death was much higher in AH18 than in the wild type. It is inferred that the peroxidase provides protection against H2O2 in log-phase cells and that the catalase-peroxidase provides protection under the oxidative conditions that prevail in aging cultures. This protective function might be related to the dual activity of the latter as a catalase and a peroxidase or to its capacity to oxidize NADH, NADPH, and cytochrome c.     

Physiological evolution in the branchiopods

The interactions of physiological and morphological evolution are discussed in relation to the branchiopod crustaceans. Many branchiopods are morphologically relatively primitive and evade competition from more advanced forms by physiological adaptations which enable them to survive in extreme environments. The most recently evolved group of branchiopods, the Cladocera, or water fleas, have specialisation of morphology and reproduction which have enabled them to return to less extreme freshwater environments. Most recently they have developed physiological adptations which enable them to exploit the marine and other saline environments.     

"Alien" wasps and evolution of development

A comparative analysis of early developmental programs in a group of parasitic wasps reveals that closely related species can undergo dramatic evolutionary shifts in their patterns of embryogenesis. Developmental changes detected include alterations in early cleavage divisions, the establishment of embryonic anteroposterior polarity and modifications of the segmentation gene hierarchy described from Drosophila. These changes appear to be adaptations to parasitic development, taking place within the body of the host. Wasps illustrate a surprising plasticity in their early development and embryogenesis. The alterations associated with different parasitic strategies suggest that ecological adaptations may have profound influences on developmental processes in animals.     

Anthropometric and physiological properties in the determination of biological distances.

The investigation of anthropometric dimensions of the body and head, lung function tests and blood pressure was carried out in 3 separate groups. The analysis of 'distances' between particular pairs of the analyzed groups was performed by Penrose's CH2 and its components CQ2 and (v-l/v)CZ2. It is pointed to various ways of diversification of particular characteristics, which is likely to depend on different selective inertia of particular traits, that is, on different intensity of the effect of genetic and/or ecological factors on their formation. It is shown that as many different biological characteristics of human groups as possible should be taken into consideration for the calculation of 'distances'.     

关于"探究问题"的课题开展及思考

“探究问题”的课题研究,让学生学会如何收集、处理和提取信息,如何运用相关知识分析和解决实际问题,如何与他人交流与合作,如何表述或展示研究的成果等等,达到学以致用的目的。     

Investigating the evolution and development of biological complexity under the framework of epigenetics

Biological complexity is a key component of evolvability, yet its study has been hampered by a focus on evolutionary trends of complexification and inconsistent definitions. Here, we demonstrate the utility of bringing complexity into the framework of epigenetics to better investigate its utility as a concept in evolutionary biology. We first analyze the existing metrics of complexity and explore the link between complexity and adaptation. Although recently developed metrics allow for a unified framework, they omit developmental mechanisms. We argue that a better approach to the empirical study of complexity and its evolution includes developmental mechanisms. We then consider epigenetic mechanisms and their role in shaping developmental and evolutionary trajectories, as well as the development and organization of complexity. We argue that epigenetics itself could have emerged from complexity because of a need to self‐regulate. Finally, we explore hybridization complexes and hybrid organisms as potential models for studying the association between epigenetics and complexity. Our goal is not to explain trends in biological complexity but to help develop and elucidate novel questions in the investigation of biological complexity and its evolution.