Thresholds for cold-torpor and cold-survival in the Queensland fruit fly,and predictability of rates of change in survival threshold

Temperature thresholds for both cold-torpor and cold-survival in post-teneral D. tryoni can be predicted entirely on the basis of thermal history, regardless of age. There is a direct link between the torpor threshold of post-teneral flies of any age and the mean time that flies of any post-teneral age can survive at any one low temperature. Mean survival time at any one low temperature can therefore be predicted if the torpor threshold is first predicted by using the model of Meats which only requires data on thermal history.     

On the distribution of the general irreversiblen-compartmental model having time-dependent transition probabilities

The cumulant generating function and first two moments are derived for the stochastic distribution of units in a general irreversiblen-compartment model with time-dependent transition probabilities. In this model, a unit in the first compartment can transfer to any one of the remainingn−1 compartments and a unit in the second compartment can transfer to any of the remainingn−2 compartments and so on. In addition, a unit can enter or leave the system through any compartment. The work is related to previous research and a numerical example is given.     

Using a novel approach — recombineering — to generate odf2 null alleles

This article uses a real-life example to illustrate the concept and methodology of recombineering,a revolutionary genetic engineering technique based on phage-mediated homologous recombination.A step-b...     

DNA electromagnetic properties and interactions -An investigation on intrinsic bioelectromagnetism within DNA

The question whether intrinsic bioelectromagnetism exists within DNA or not is an important and so far unexplored area of biology. We carried out a study of isolated genetic material, utilizing both prokaryotic and eukaryotic DNA, to measure any possible intrinsic electromagnetic effects or fields emanated within the molecules. Studies were carried out with extremely sensitive ultra-low-noise trans-impedance amplifiers and a high-precision data acquisition system to record any possible faintest electromagnetic signals from the concentrated, as well as diluted DNA, in vitro. Some experiments were performed to investigate any possible electromagnetic effects of high-frequency (HF) RF fields on the DNA under test. However, after extensive testing and careful measurements, we failed to detect any possible intrinsic or induced electromagnetic activity from the DNA as compared to simple water or empty chambers. We reached a conclusion that there does not seem to be any measurable intrinsic electromagnetic activity or fields present in the DNA material, whether in concentrated or diluted form, and if there were, any such activity or fields would be extremely minuscule to be detected with scientific precision by current human measurement methods.     

Testing Magnetic Orientation in a Solitary Subterranean Rodent Ctenomys talarum (Rodentia: Octodontidae)

To test for the hypothesis that Ctenomys talarum can use the earth's magnetic field for spatial orientation, we carried out field and laboratory experiments to analyse if C. talarum burrows present any geomagnetic orientation in their natural habitat, if C. talarum show any spontaneous directional preference when starting to excavate their burrows and if this subterranean rodent is capable to use the earth's magnetic field to orient towards a goal in a complex maze. No correlation between the burrowing direction and the earth's magnetic field was found. We could not find any evidence for any spontaneous directional preference when starting to excavate the burrows in C. talarum. The change of the horizontal vector of the geomagnetic field did not affect the ability of this rodent to orient towards a goal in an artificial labyrinth. Explanations for these results and other possible mechanisms of orientation that could be used by C. talarum are discussed.     

NO EFFECT OF ENVIRONMENTAL HETEROGENEITY ON THE MAINTENANCE OF GENETIC VARIATION IN WING SHAPE IN DROSOPHILA MELANOGASTER

Theory suggests that heterogeneous environments should maintain more genetic variation within populations than homogeneous environments, yet experimental evidence for this effect in quantitative traits has been inconsistent. To examine the effect of heterogeneity on quantitative genetic variation, we maintained replicate populations of Drosophila melanogaster under treatments with constant temperatures, temporally variable temperature, or spatially variable temperature with either panmictic or limited migration. Despite observing differences in fitness and divergence in several wing traits between the environments, we did not find any differences in the additive genetic variance for any wing traits among any of the treatments. Although we found an effect of gene flow constraining adaptive divergence between cages in the limited migration treatment, it did not tend to increase within‐population genetic variance relative to any of the other treatments. The lack of any clear and repeatable patterns of response to heterogeneous versus homogeneous environments across several empirical studies suggests that a single general mechanism for the maintenance of standing genetic variation is unlikely; rather, the relative importance of putative mechanisms likely varies considerably from one trait and ecological context to another.     

Dynamical properties of Discrete Reaction Networks

Reaction networks are commonly used to model the dynamics of populations subject to transformations that follow an imposed stoichiometry. This paper focuses on the efficient characterisation of dynamical properties of Discrete Reaction Networks (DRNs). DRNs can be seen as modeling the underlying discrete nondeterministic transitions of stochastic models of reaction networks. In that sense, a proof of non-reachability in a given DRN has immediate implications for any concrete stochastic model based on that DRN, independent of the choice of kinetic laws and constants. Moreover, if we assume that stochastic kinetic rates are given by the mass-action law (or any other kinetic law that gives non-vanishing probability to each reaction if the required number of interacting substrates is present), then reachability properties are equivalent in the two settings. The analysis of two types of global dynamical properties of DRNs is addressed: irreducibility, i.e., the ability to reach any discrete state from any other state; and recurrence, i.e., the ability to return to any initial state. Our results consider both the verification of such properties when species are present in a large copy number, and in the general case. The necessary and sufficient conditions obtained involve algebraic conditions on the network reactions which in most cases can be verified using linear programming. Finally, the relationship of DRN irreducibility and recurrence with dynamical properties of stochastic and continuous models of reaction networks is discussed.     

Signal propagation in 2-dimensional threshold cellular space

Summary A two-dimensional network of uniformly connected McCulloch-Pitts neurons is considered and signal propagations in the network are analyzed. The problems are set up in the framework of cellular space such that each cell is a copy of any given McCulloch-Pitts neuron and is connected to the nearest neighboring cells. It is assumed that the threshold value is positive and that there exists only one firing cell at the beginning. Then it is shown that essentially there are only four signal propagation patterns and a firing pattern at any time t can be obtained by such a superposition of the propagation patterns that includes the newly defined concept of dominance and assimilation. The exact formulae representing firing patterns at any time t are obtained for any finite rectangle cell space with constant 0 (i.e., non-firing) boundary condition and for the entire two-dimensional cellular space.     

The fine structure of plant tumors

Summary Crown gall cells of several plant species contain considerably more endoplasmic reticulum than their normal or hyperplastic counterparts. This characteristic appears to be stable even in crown gall tissues grownin vitro for many years. No evidence for the presence of an etiological agent was found in any of the crown gall cells, nor was there any evidence of any structure peculiar to these cells. It is not possible at this time to determine if this increase in endoplasmic reticulum is responsible for the increased biosynthetic capacities of tumor cells.     

Dietary Sugar and Ischaemic Heart Disease

Comparison of the sugar intake of 1,158 men believed to be free of ischaemic heart disease failed to establish any real difference in intake when compared with 170 men with confirmed or possible ischaemic heart disease. In neither group was mere any significant correlation between sugar intake and serum cholesterol, white blood cell count, haemoglobin, E.S.R., β-lipoprotein, or uric add; nor was there any correlation between total sugar intake and weight gain after the age of 25 years.These results suggest that considerably more confirmation is required before acceptance of Yudkm''s hypothesis that high sugar intake is the chief dietary factor causing ischaemic heart disease.     

Parentalité et Individualité

The concept of parenthood needs to be redefined in relation to the new uses of sexuality and reproduction. Exclusively from the view of point of personal freedom, a “parent” is any person who has chosen to define himself/herself in this way with reference to the existence of another individual, whoipso facto benefits from this same freedom, limiting his/her own freedom. This redefinition is derived from an unlimited right to parenthood for any individual who chooses parenthood, an unlimited right to abortion for any unwanted pregnancy, and absolute prohibition of abortion for congenital malformations.     

THE EGG WHITE PROTEIN EVIDENCE FOR RATITE AFFINITIES

The egg white proteins of the large ratites ( Struthio, Casuarius, Dromaius, Rhea ), the kiwis ( Apteryx ) and several tinamous (Tinamidae) were compared with one another and representatives of several other groups of birds using the technique of isoelectric focusing in acrylamide gel. The tryptic peptides of the ovalbumins of the same groups were compared by thin-layer electrophoresis. The results indicate that the large ratites are more closely related to one another than any one of them is to any other living bird; that the kiwis are not closely related to any of the other groups with which they were compared; and that the tinamous are not closely related to any of the large ratites but may be distantly related to the Galliformes.     

Antiviral and Antiproliferative Activities of Three Molecular Components of Leukocyte-Derived Human Interferon

Antiviral and antiproliferative activities of three naturally occurring components of leukocyte-derived human interferon (HuIFN-α) separated by concanavalin A-agarose affinity chromatography were studied in a variety of neoplastic cell lines. Significant differences were seen with these different components. The results strongly suggest that careful consideration must be given while selecting any one component of HuIFN-α for any of the antiviral or antiproliferative studies. There is no clear evidence that glycosylation of HuIFN-α has any significant influence on its in vitro antiviral or antiproliferative activities, although apparently glycosylated and non-glycosylated components gave different antiviral and antiproliferative responses in different tumor cells.     

The energy flux theory 35 years later: formulations and applications

Several models have been proposed for the energetic behavior of the photosynthetic apparatus and a variety of experimental techniques are nowadays available to determine parameters that can quantify this behavior. The Energy Flux Theory (EFT) developed by Strasser 35 years ago provides a straightforward way to formulate any possible energetic communication between any complex arrangement of interconnected pigment systems and any energy transduction by these systems. We here revisit the EFT, starting from the basic general definitions and equations and presenting applications in formulating the energy distribution in photosystem (PS) II units with variable connectivity, as originally derived, where certain simplifications were adopted. We then proceed to the derivation of equations for a PSII model of higher complexity, which corresponds, from the formalistic point of view, to the later formulated and now broadly accepted exciton–radical-pair model. We also compare the formulations derived with the EFT with those obtained, by different approaches, in the classic papers on energetic connectivity. Moreover, we apply the EFT for the evaluation of the excitation energy distribution between PSII and PSI and the distinction between state transitions and PSII to PSI excitation energy migration. Our analysis demonstrates that the EFT is a powerful approach for the formulation of any possible model, at any complexity level, even of models that may be proposed in the future, with the advantage that any possible energetic communication or energy transduction can be easily formulated mathematically by trivial algebraic equations. Moreover, the biophysical parameters introduced by the EFT and applicable for any possible model can be linked with obtainable experimental signals, provided that the theoretical resolution of the model does not go beyond the experimental resolution.     

Sober and Elgin on laws of biology: a critique

In this short discussion note, I discuss whether any of the generalizations made in biology should be construed as laws. Specifically, I examine a strategy offered by Elliot Sober (1997) and supported by Mehmet Elgin (2006) to reformulate certain biological generalizations so as to eliminate their contingency, thereby allowing them to count as laws. I argue that this strategy entails a conception of laws that is unacceptable on two counts: (1) Sober and Elgin’s approach allows the possibility of formulating laws describing any biological phenomenon whatsoever; and (2) on Sober and Elgin’s view, any interesting contrast between so-called laws and obviously accidental generalizations collapses. I conclude by offering suggestions to refine their view in order to avoid these theoretical problems.     

Effects on Respiratory and Circulatory Dynamics

There are exceptions and variations to the general clinical rule that muscle relaxants depress respiration and have no effect on circulation.Variation may be attributed to differences in animal species, in individual response, in muscle affected, in drug used and in dose employed.Conclusions about muscle relaxants derived from animal experiments cannot always be assumed to apply to man.The “respiratory sparing” action of a muscle relaxant cannot be relied upon in any individual patient. Facilities for adequate artificial respiration must always be available when any dose of any muscle relaxant drug is administered.Muscle relaxants affect circulation by inhibition of parasympathetic and sympathetic ganglia, by anticholinesterase activity and by release of histamine.     

Improved Equations for the Prediction of Seed Longevity

Equations for predicting seed longevity in storage have beenimproved so that they now take into account variations withina species in initial seed quality—which is affected bygenotype and pre-storage environment—and so that theyare more accurate over a wider range of storage environmentsThese improvements have been incorporated into a seed viabilitynomograph for barley (Hordeum distichum L.) which may be usedto predict percentage viabihty of any seed lot after any timein any storage environment within the range –20 to 90°C and 5–25 per cent moisture content. Applicationsof the improved equations to seed drying and to long-term seedstorage for genetic conservation are discussed. Hordeum distichum L., barley, seed viability, seed longevity prediction, seed storage, seed drying, storage temperature, seed moisture content, genetic resources conservation     

Impact of using multiple causes of death codes to compute site-specific, death certificate-based cancer mortality statistics in the United States

Background: Cancer mortality statistics, an important indicator for monitoring cancer burden, are traditionally restricted to instances when cancer is determined to be the underlying cause of death (UCD) based on information recorded on standard certificates of death. This study's objective was to determine the impact of using multiple causes of death codes to compute site-specific cancer mortality statistics. Methods: The state cancer registries of California, Colorado and Idaho provided linked cancer registry and death certificate data for individuals who died between 2002 and 2004, had at least one cancer listed on their death certificate and were diagnosed with cancer between 1993 and 2004. These linked data were used to calculate the site-specific proportion of cancers not selected as the UCD (non-UCD) among all cancer-related deaths (any mention on the death certificate). In addition, the retrospective concordance between the death certificate and the population-based cancer registry, measured as confirmations rates, was calculated for deaths with cancer as the UCD, as a non-UCD, and for any mention. Results: Overall, non-UCD deaths comprised 9.5 percent of total deaths; 11 of the 79 cancer sites had proportions greater than 3 standard deviations from 9.5 percent. The confirmation rates for UCD and for any mention did not differ significantly for any of the cancer sites. Conclusion and impact: The site-specific variation in proportions and rates suggests that for a few cancer sites, death rates might be computed for both UCD and any mention of the cancer site on the death certificate. Nevertheless, this study provides evidence that, in general, restricting to UCD deaths will not under report cancer mortality statistics.     

The effects of incomplete protein interaction data on structural and evolutionary inferences

Background  

Present protein interaction network data sets include only interactions among subsets of the proteins in an organism. Previously this has been ignored, but in principle any global network analysis that only looks at partial data may be biased. Here we demonstrate the need to consider network sampling properties explicitly and from the outset in any analysis.