The dynamics of the lynx–hare system: an application of the Lotka–Volterra model

The Lotka–Volterra model of predator–prey dynamics was used for approximation of the wellknown empirical time series on the lynx–hare system in Canada that was collected by the Hudson Bay Company in 1845–1935. The model was assumed to demonstrate satisfactory data approximation if the sets of deviations of the model and empirical data for both time series satisfied a number of statistical criteria (for the selected significance level). The frequency distributions of deviations between the theoretical (model) trajectories and empirical datasets were tested for symmetry (with respect to the Y-axis; the Kolmogorov–Smirnov and Lehmann–Rosenblatt tests) and the presence or absence of serial correlation (the Swed–Eisenhart and “jumps up–jumps down” tests). The numerical calculations show that the set of points of the space of model parameters, when the deviations satisfy the statistical criteria, is not empty and, consequently, the model is suitable for describing empirical data.     

The twenty-fifth anniversary of the Limnological Institute,The Netherlands (1957–1982)

This paper marks the silver jubilee in 1982 of the Limnological Institute, The Netherlands. It describes the history, present research programme and organisation of the Institute, as well as its cooperative studies with other institutes and its training facilities.Some remarks about its future plans of work are made.     

The liver: an organ of the immune system?

The liver stands in a unique position between the gastrointestinal tract and systemic venous system. Its constant exposure to food antigens, bacterial products and potential pathogens through the mesenteric circulation, requires the liver to maintain tolerogenic capabilities while preserving the means to mount effective immune responses. The liver has the unique ability amongst solid organs, to activate na?ve CD8+ T lymphocytes in an antigen-specific manner. However, this activation can be inefficient and lead to apoptosis. This phenomenon is believed to be involved in both, the development of oral tolerance and the induction of tolerance in liver allografts. The liver is the target of both autoimmune diseases and of chronic viral infections and its unique tolerogenic environment has frequently been suggested as a factor in the development of these diseases. A better grasp of the liver's unique immunological processes would lead to a better understanding of immune tolerance mechanisms and their role in the development of autoimmune diseases and chronic viral infections.     

The golden age of Drosophila research at the Universidade de S?o Paulo (USP): A testimonial on the decades 1940–1950

This article is a testimonial written by the first author regarding the research work performed with Drosophila between 1943 and 1959, at the Departamento de Biologia Geral of the Universidade de São Paulo (USP), which permitted the building of a nucleus of excellence. This research work, focused on the systematics and population genetics of the Neotropical species, began during the first of Dobzhansky’s six visits to USP. Special attention was given to the multinational megaprojects conducted during his longer stays, from August 1948 to July 1949 and from June 1955 to July 1956. The role played by the Rockefeller Foundation is duly remembered, and so is the undeniable contribution brought by Dobzhansky, to the establishment of several laboratories dedicated to research in the field of natural population genetics and to the qualification of human resources. On the other hand, important “backstage” episodes are retrieved which were omitted in the official history and occurred from the planning to the execution of the project, carried out on the Angra dos Reis islands. Special attention was given to the relationship problems which resulted from Dobzhansky’s, the leader’s, difficult personality and contributed to the failure of the second and last multinational project.     

Biomass productivity of Scenedesmus dimorphus (Chlorophyceae) was improved by using an open pond–photobioreactor hybrid system

The industrialization of microalgae-based biofuel production has been hampered by low biomass productivity of conventional open ponds. In this research, a hybrid cultivation system that combined an open pond and photobioreactor (PBR), with broth circulating between both, was introduced. The hybrid system was tested under indoor and outdoor conditions using the oleaginous microalgal species Scenedesmus dimorphus. When the PBR(s) in the hybrid system reinforced the light supply to the carbon-replete open pond the biomass reached 1.34 g l^–1, 116% higher than in the non-hybrid system. Subsequent studies showed that higher circulation speed and low volume ratio of PBR vs. open pond would further improve the hybrid effects. When applied outdoors at pilot scale, the biomass productivity of the hybrid system increased 46.3–74.3% compared with the open pond and in September was 12.5% higher than that of PBRs. These results indicate that hybrid cultivation might be a cost-effective way to improve the light usage efficiency of current open pond systems.     

Timeline of Genomics (1901–1950)

Year Event and Theoretical Implication/Extension1901 Hugo de Vries adopts the term MUTATION to describe sudden, spontaneous, drastic alterations in the hereditary material of Oenothera. Thomas Harrison Montgomery studies sper- matogenesis in various species of Hemiptera and ?nds that maternal chromosomes only pair with paternal chromosomes during meiosis. Clarence Ervin McClung postulates that the so- called accessory chromosome (now known as the “X” chromosome) is male determining.…     

The phosphorus budget of the Marsdiep tidal basin (Dutch Wadden Sea) in the period 1950–1985: importance of the exchange with the North Sea

Nutrient and carbon budgets of the western part of the Dutch Wadden Sea are based on the concept formulated by Postma (1954): import of organic compounds from the North Sea, mineralization in the estuary ans subsequently an export of dissolved inorganic nutrients to the North Sea. In this paper the phosphorus budget of the westernmost part of the Wadden Sea (Marsdiep basin) during the period 1950–1985 is considered to evaluate this concept and to investigate whether eutrophication processes have changed these P-budgets during the last decades. Most attention is paid to the importance of the exchange of P-components between the tidal basin and the open sea. The budgets are based on a general mass balance equation in which the main entries are the loadings via the freshwater sources, the net sediment-water exchange, the exchange with the North Sea, the input from the adjacent Vlie basin, and a transformation term representing the interchange between dissolved and particulate phosphorus. Averaged over the entire period 55% of the phosphate input (SRP) to the basin is delivered by the fresh water sources, and 45% by the Vlie basin. For non-SRP components these numbers are 50% and 40% respectively, while only 10% comes from the North Sea. The import from the North Sea, as calculated by our model thus seems less important than previously documented. There is a clear effect of the eutrophication during the last decades. In the first 20 years of the period investigated there was a moderate increase in the TP input to the basin, partly caused by an increasing input of non-SRP (TP minus soluble reactive phosphorus) from the North Sea. In 1970/71 almost 30% of the non-SRP loading originated from the North Sea. From approximately 1975 onwards this import of non-SRP turns into an export, while the TP-loading from the other sources inclined, until a maximum was reached in 1981. Recently a decrease in the TP-inputs has been observed. It is concluded that the recent output of phosphorus from the Marsdiep basin may have a considerable impact on the adjacent area of the North Sea.Publication no. 2 of the project Applied Scientific Research Neth Inst. for Sea Res. (BEWON).     

The Recurrence of Parathuramminacea and Archaesphaeracea Representatives at the Tournaisian–Viséan Boundary of the Lower Carboniferous (the Kipchak Section,the Eastern Slope of the Southern Urals)

Paleontological Journal - The Tournaisian–Viséan boundary of the Lower Carboniferous was established in carbonate facies deposits of the “Kipchak” section (Southern Urals)....     

The Rosenzweig–MacArthur system via reduction of an individual based model

Journal of Mathematical Biology - The Rosenzweig–MacArthur system is a particular case of the Gause model, which is widely used to describe predator–prey systems. In the classical...     

The state of the reproductive system of the tench Tinca tinca (1999–2005) from water bodies polluted as a result of the catastrophe at the Chernobyl Nuclear Power Plant

The state of the reproductive system of Tinca tinca—descendants of individuals that were exposed to radiation as a result of the catastrophe at the Chernobyl Nuclear Power Plant in 1986 was studied. Material was collected in the postemergency period in radionuclide-polluted water bodies: in the Ukraine, in Kiev Reservoir, the Teterev River, and Lake Glubokoe (1999–2005) and in Belarus, in Lake Svyatoe (1998–1999). It is demonstrated that the total number and the extent of disturbances in the gonads of T. tinca are positively related to the levels of pollution in water bodies: in the cleanest water body, the Teterev River, the proportion of fish with gonads without considerable deviations was about 93%; in Kiev Reservoir, 79%, and in Lake Svyatoe, only 18%. Among the “postemergency” generations of T. tinca, the maximum number of disturbances in sexual cells and gonads was recorded in F_3–4, which is evidently caused by a phenomenon of the “prolonged mutagenesis”. A relatively high species resistance of the reproductive system of T. tinca to the radiation impact, in comparison with other cyprinids, was recorded.     

The effects of nociceptin peptide (N/OFQ)–receptor (NOP) system activation in the airways

The heptadecapeptide nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the N/OFQ peptide (NOP) receptor. It is cleaved from a larger precursor identified as prepronociceptin (ppN/OFQ). NOP is a member of the seven transmembrane-spanning G-protein coupled receptor (GPCR) family. ppN/OFQ and NOP receptors are widely distributed in different human tissues. Asthma is a complex heterogeneous disease characterized by variable airflow obstruction, bronchial hyper-responsiveness and chronic airway inflammation. Limited therapeutic effectiveness of currently available asthma therapies warrants identification of new drug compounds. Evidence from animal studies suggests that N/OFQ modulates airway contraction and inflammation. Interestingly up regulation of the N/OFQ–NOP system reduces airway hyper-responsiveness. In contrast, inflammatory cells central to the inflammatory response in asthma may be both sources of N/OFQ and respond to NOP activation. Hence paradoxical dysregulation of the N/OFQ–NOP system may potentially play an important role in regulating airway inflammation and airway tone. To date there is no data on N/OFQ–NOP expression in the human airways. Therefore, the potential role of N/OFQ–NOP system in asthma is unknown. This review focuses on its physiological effects within airways and potential value as a novel asthma therapy.     

The census of heronries, 1960–61

Capsule Eleonora's Falcons wintering in Madagascar selected degraded humid forests and cultivated areas close to pristine humid forest.

Aims To identify the habitat preferences of Eleonora's Falcon Falco eleonorae on their wintering grounds in Madagascar, and to use this information to gain insights into the conservation priorities of this species.

Methods A total of 11 Eleonora's Falcons were captured in Spain in 2007 and 2008 and equipped with solar-powered satellite transmitters. We obtained information on five complete wintering events for three birds, two of them tracked for two consecutive years. Data were analyzed using geographic information system-based cartography.

Results The analyses showed a preference for degraded humid forests and cultivated lands within areas where pristine humid forests were the most abundant habitat type.

Conclusions Eleonora's Falcons could be taking advantage from a spill-over edge effect of their insect prey into cultivated and more open areas close to humid forests. However, the importance of humid forests for Eleonora's Falcons seems to be high. The current loss of this habitat in Madagascar is a cause for concern with respect to the conservation of this long-distance migratory falcon species.     

Theoretical study of the hydroxylation of phenols mediated by an end-on bound superoxo–copper(II) complex

Peptidylglycine α-amidating monooxygenase and dopamine β-monooxygenase are copper-containing proteins which catalyze essential hydroxylation reactions in biological systems. There are several possible mechanisms for the reductive O₂-activation at their mononuclear copper active site. Recently, Karlin and coworkers reported on the reactivity of a copper(II)–superoxo complex which is capable of inducing the hydroxylation of phenols with incorporated oxygen atoms derived from the Cu(II)-O₂ ^·− moiety. In the present work the reaction mechanism for the abovementioned superoxo complex with phenols is studied. The pathways found are analyzed with the aim of providing some insight into the nature of the chemical and biological copper-promoted oxidative processes with 1:1 Cu(I)/O₂-derived species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Experimental Stations of the Institute of Experimental Biology and the Development of Russian Genetics (1917–1929)

Russian Journal of Developmental Biology - The history of the experimental stations of the Institute of Experimental Biology organized near Moscow by N.K. Kol’tsov, the founder of the...     

Modelling of the mechanical and mass transport properties of auxetic molecular sieves: an idealised inorganic (zeolitic) host–guest system

Force field based simulations have been employed to model the structure, and mechanical and mass transport properties of the all-silica zeolite MFI (ZSM5—Si₉₆O₁₉₂). Undeformed and deformed MFI subject to uniaxial loading in each of the three principal directions were investigated. The mechanical properties are predicted to include negative on-axis Poisson's ratios (auxetic behaviour) in the x ₁–x ₃ plane of the undeformed structure, and are strain-dependent. Transformation from positive-to-negative Poisson's ratio behaviour, and vice versa, is predicted for most on-axis Poisson's ratios at critical loading strains. Simulations of the simultaneous sorption of neopentane and benzene guest molecules onto the undeformed host MFI framework indicate a low neopentane-to-benzene loading ratio, consistent with experimental observation. The sorption of these two molecular species onto deformed MFI is Poisson's ratio- and strain-dependent. Uniaxial tensile loading along a direction containing a negative on-axis Poisson's ratio leads to an increase in the loading of the larger neopentane molecules with respect to benzene, strongly correlated with the increase in volume associated with auxetic behaviour.