Theoretical Biology Forum最新文献

Long-lived and slow reproducing species, such as cetaceans, are among the most critical conservation units: a demographic approach can be very useful for their management and conservation. In the present work, we examined, by demographic tools, the most exhaustive photo-identification database available for the Mediterranean fin whale (Balaenoptera physalus) population, recorded by Tethys Research Institute between 1990 and 2007 in the Western Ligurian Sea. A total of 31,782 km were covered and 548 fin whale sightings were recorded. The occurrence of the target species was uneven across the years and months: an anomalous reduction of sightings occurred between 2001 and 2004. Moreover, the target species is likely to concentrate in the study area in the summer months and probably moves to other areas in the early autumn. Using the photo-identification technique, 431 different individuals were photo-identified, but only 318 of them were sized: 6 calves (≤ 10 meters), 33 immature (10-15 m), 261 adolescent-adult (> 15 m) and 18 olds (≥ 20 m). For the first time the site of the fin whale sub-population in the Pelagos Sanctuary was obtained by photo-identification and mark-recapture techniques. These techniques were used to estimate the site of the sub-population composed by individuals > 15 meters as 539 fin whales (95% confidence interval = 345-732) over the period 1990-1999. The number of calves was likely underestimated, as the sighting period (late spring-summer) was shifted with respect to the peak of births (late autumn). To fill this gap of knowledge we propose a simple mathematical model for the yearly dynamics of calves. After correcting the number of calves, a static life history table for the period 1990-2007 was set out. Our results highlight the highest survival proportions between calf and immature (61.1%) and the minimum between adolescent-adult and old (2.5%) vital stages. The overall life expectancy is estimated to be 6.3 years while the life expectancy of individuals entering the adolescent-adult stage is 14.3 years. This paper aims at providing a contribution for improving the conservation efforts and the demographic knowledge on fin whales in the Pelagos Sanctuary.

Bioengineering is the consideration of biological problems from modern engineering, therefore money-oriented, perspective. Today, grant-giving bodies always favor bioengineering projects rather than pure biology projects (like those in ecology, entomology, etc.). Therefore, today's biologist is forced to be on the horns of a dilemma. They have to either submit a very powerful and valid reason for the proposal of their project, or change the project to one having a potential of money-based outcome. On the other hand, because of dealing with the living components of nature, conducting a research in pure biology is like a kind of worship. For this reason, from a believer scientist's view, a deviation (in terms of research) from biology to bioengineering can be considered like committing a sin. Unfortunately, today's wild capitalism has been bringing new sinners day by day, and this system will continue for the foreseeable future unless grant-giving bodies comprehend the real importance of pure biology.

In this paper we introduce the framework for the application of statistical mechanics to network theory, with a particular emphasis to the concept of entropy of network ensembles. This formalism provides novel observables and insights for the analysis of high-throughput transcriptomics data, integrated with apriori biological knowledge, embedded in-to available public databases of protein-protein interaction and cell signaling.

In a recent paper, Michel and Pirillo prove that there are 24 dinucleotide circular codes of maximum cardinality over an alphabet of cardinality 4. In this paper we find the exact number of dinucleotide circular codes of maximum cardinality for any given (finite) cardinality of the alphabet. Moreover, we describe the structure of these codes.

In this study, influenza is modeled dynamically under seasonal variables. Seasonal variables made this model geometrically more complicated than without seasonal conditions. This modeling will be done in two cases with vaccination and without vaccination. These two models are solved in similar conditions by using Rung-Kutta method. The resulted data are shown in two diagrams and they are compared. We deduce a model for influenza without seasonal variable and vaccination and we consider its equilibrium points.

For thousands of years the plants were considered only as a source of food and medicine, and as ornamental objects. Only from the fifth century BC, some philosophers of Ancient Greece realized that the plants were living organisms but, unfortunately, their works have come to us as fragments that we often know from the biological works of Aristotle. This eminent philosopher and man of science, however, did not give us a complete work on the plants, which he often promised to write. From scattered fragments of his conspicuous biological work, it emerges a concept of nutritive soul that, in the presence of heat and moisture, allows plants to grow and reproduce. The task of writing a comprehensive botanical work was delegated to his first pupil, Theophrastus, who left us two treatises over time translated into the various languages up to the current versions (Enquiry into plants, On the causes of plants). The plant life is described and interpreted on the basis of highly accurate observations. The physiological part of his botany is essentially the nutrition: According to Theophrastus, plants get matter and moisture from the soil through root uptake and process the absorbed substances transforming them into food, thanks to the heat. The processing (pepsis, coction) of matter into the food represents an extraordinary physiological intuition because individual organs of a plant appear to perform its specific transformation. Despite that Theophrastus did not do scientific experiments or use special methods other than the sharpness of his observations, he can be considered the forerunner of a plant physiology that would take rebirth only after two millennia.

Once considered a passive reservoir for lipid storage and an inert provider of thermal/mechanical insulation, white adipose tissue (WAT) is presently seen as a highly dynamic endocrine organ that actively modulates a variety of physiologic processes, including energy balance, food intake, inflammation, immunity, metabolism, as well as cardio-vascular (CV) and neuroendocrine homeostasis. Actually, other than fatty acids and lipid moieties, WAT secretes a wide range of bioactive factors, considerably different in therms of structure and functions, including cytokines, chemokines, growth factors, complement system molecules, acute phase reactants, and hormones, among which the products predominantly or exclusively synthesized by and released from adipocytes are categorized as "adipokines". The adipokine expression is intimately linked to various parameters of adiposity (such as total body fat, percentage of body fat, and fat distribution), resulting generally (with very few exceptions, such as adiponectin, omentin, and Zinc-alpha2-glycoprotein) in positive correlation with WAT mass. The adipokine profiles undergo opposite changes in WAT excess or deficiency/dystrophy. In obese subjects, the altered adipokine network strikingly contributes to the development of systemic low-grade inflammation, as well as of obesity-related metabolic/CV comorbidities, that collectively define the so called metabolic syndrome. Adipokine dysregulation has been also observed in patients with chronic inflammatory/autoimmune disorders, such as connective tissue diseases, and adipokine pathway targeting has been thought to represent a potential innovative therapeutic perspective. Comprehensive advances in understanding the WAT biology and signaling may provide crucial insights into the physiopathology of the whole body homeostasis.

Contrary to the received view of Richard Owen as a Platonic and conservative naturalist, we document that he held a radically physicalist worldview that extended to so tough a matter as the Mind/Body Problem. We argue that if viewed from the perspective of his overall comparative project, Owen's reflections on the nature of mind at the end of volume III of On the anatomy of vertebrates can be read as an anticipation of some of the main tenets of the Brain State Theory of mind developed since the mid 20th century.

Understanding biological behaviours implies explaining the organization of living beings. Cancer compromises the normal structure and function of tissues, cells, and genes so that it appears as a multilevel phenomenon. The biology of cancer is thus giving us interesting insights on the organization of a biological system and its hierarchical phenomenology. My thesis is that understanding the dynamics of this biological system implies making explicit features of a non-univocal notion of organization and two different dimensions of the parts-whole dependence, i.e. different modes of causality in maintaining levels of organization. The argument follows the analysis of some features of the biology of cancer. Convergence of interpretative models towards an operational account of levels, i.e. through concepts that focus on the dynamic control of levels' organization, contributes to this analysis too. A multi-unity perspective replaces the parts-whole perspective to explain what conditions the hierarchical control of biological behaviours depends on and how that dependency works.