Chemical and tactile communication between the root aphid parasitoidParalipsis enervis and trophobiotic ants: consequences for parasitoid survival

Females of the aphid parasitoidParalipsis enervis received liquid food by regurgitation (trophallaxis) from workers of the ant speciesLasius niger, but were not fed by workers ofMyrmica laevinodis andTetramorium caespitum. WhileP. enervis was not treated aggressively by workers of any of these species,Lasius flavus workers killed the parasitoid. This different ant behaviour resulted in a different parasitoid longevity. WhileP. enervis survived for only 10 min in the presence ofL. flavus (due to ant aggression) or for approximately one day in the presence ofT. caespitum andM. laevinodis (due to lack of trophallaxis), survival increased significantly to more than five days in the presence ofL. niger, which provided food regularly to the parasitoids. Our study suggests thatP. enervis mimics behavioural signals ofL. niger, as well as odor cues of its host aphidAnoecia corni, to avoid aggression byL. niger.     

Explaining Leibniz equivalence as difference of non-inertial appearances: Dis-solution of the Hole Argument and physical individuation of point-events

“The last remnant of physical objectivity of space–time” is disclosed in the case of a continuous family of spatially non-compact models of general relativity (GR). The physical individuation of point-events is furnished by the autonomous degrees of freedom of the gravitational field (viz., the Dirac observables) which represent—as it were—the ontic part of the metric field. The physical role of the epistemic part (viz. the gauge variables) is likewise clarified as embodying the unavoidable non-inertial aspects of GR. At the end the philosophical import of the Hole Argument is substantially weakened and in fact the Argument itself dissolved, while a specific four-dimensional holistic and structuralist view of space–time (called point-structuralism) emerges, including elements common to the tradition of both substantivalism and relationism. The observables of our models undergo real temporal change: this gives new evidence to the fact that statements like the frozen-time character of evolution, as other ontological claims about GR, are model dependent.     

Forecasting for the generation of trading signals in financial markets

In this paper we show that optimal trading results can be achieved if we can forecast a key summary statistic of future prices. Consider the following optimization problem. Let the return r_i (over time i=1, 2, ..., n) for the ith day be given and the investor has to make investment decision d_i on the ith day with d_i=1 representing a ‘long' position and d_i=0 a ‘neutral' position. The investment return is given by r=Σⁿ_i=1r_id_i−cΣⁿ⁺¹_i=1∣d_i−d_i−1∣, where c is the transaction cost. The mathematical programming problem of choosing d₁, ..., d_n to maximize r under a given transaction cost c is shown to have an analytic solution, which is a function of a key summary statistic called the largest change before reversal. The largest change before reversal is recommended to be used as an output in a neural network for the generation of trading signals. When neural network forecasting is applied to a dataset of Hang Seng Index Futures Contract traded in Hong Kong, it is shown that forecasting the largest change before reversal outperforms the k‐step‐ahead forecast in achieving higher trading profits. Copyright © 2000 John Wiley & Sons, Ltd.     

Notable diversity in hemoglobin expression patterns among species of the deep-sea clam, <Emphasis Type="Italic">Calyptogena</Emphasis>

The deep-sea clams Calyptogena nautilei and C. tsubasa, which live in the cold-seep area at a depth of 3570 m in the Nankai Trough, Japan, have abundant hemoglobins (Hbs) in erythrocytes, similar to other Calyptogena species. We determined the cDNA-derived amino acid sequences of Hbs from two Calyptogena species. C. tsubasa was found to contain two dimeric Hbs, Hb I consisting of 145 amino acid residues and Hb II with 137 residues, similar to known Hbs from C. soyoae and C. kaikoi. Sequence identity was over 90% among the orthologous chains of Calyptogena Hbs. On the other hand, surprisingly, C. nautilei contained two monomeric Hbs, Hb III containing 141 residues and Hb IV with 134 residues. In addition, Hbs III and IV showed only 33–42% sequence identity with Hbs I and II from other Calyptogena species. The distal (E7) histidine, one of the functionally important residues of the heme protein, is replaced by glutamine in all Hb chains of Calyptogena species. A phylogenetic analysis indicated that C. nautilei Hb III is closer to Hb I from other Calyptogena species. We suppose that a Hb gene was duplicated at least three times in an immediate ancestor of Calyptogena and, presumably depending on physiological conditions different Hb sets are being expressed: dimeric Hbs I and II in C. soyoae, C. kaikoi and C. tsubasa, and monomeric Hbs III and IV in C. nautilei. Received 13 May 2003; received after revision 5 June 2003; accepted 12 June 2003     

Dominance for enzyme activity inDrosophila melanogaster

Summary A regulatory element tightly linked to theGpdh locus inDrosophila melanogaster has been isolated from a natural population. Flies homozygous for second chromosomes bearing the element,H31, have half the GPDH activity of normal homozygotes. Heterozygotes betweenH31 andF orS alleles exhibit dominance in GPDH activity. Heterozygotes betweenH31, F orS andDf(2L) GdhA have half the diploid level. The contribution of theS allele to the activity inS/H31 heterozygotes is more than four times that ofH31. The regulatory element distinguishingH31 is tightly linked to theGpdh ⁺ locus.     

Zur Stratigraphie der säugetierführenden Schichten von Java

Summary According to recent geological and paleontological investigations thePithecanthropus-beds of Java are pleistocene in age. The examinations of the fossil mammalian faunæ of the island are of utmost importance for this age-determination and the following faunæ can be recognized:Tji Djolang-fauna: Middle Pliocene.Kali Glagah-fauna: Upper Pliocene.Djetis-fauna withPithecanthropus: Lower Pleistocene.Trinil-fauna withPithecanthropus: Middle Pleistocene.Ngandong-fauna withHomo neanderthalensis soloensis: Upper Pleistocene.Sampoeng-fauna with a primitive type of the Wedda-Dravida-Australoid group: Subrecent. — Micropaleontological examinations of smallerForaminifera from marine equivalents of thePithecanthropus-beds confirm the age-determinations based on mammalia. — Recent field investigations prove that the lower and middle pleistocenePithecanthropus-beds are distinctlyfolded by a post-middle-pleistocene movement; the upper pleistocene Ngandong-terraces are not folded at all.     

La formule chromosomique chez cinq espèces de Chiroptères

Summary Five species ofChiroptera were studied and the following numbers were found:Rhinolophus hipposideros Bechst.N=27;Barbastella barbastellus Schr.N=16;Plecotus auritus L.N=16;Myotis myotis Bork.N=21;Miniopterus schreibersii Kuhl,N=23. Centric fusions occur in the chromosomal evolution ofChiroptera. Sex-chromosomes ofX-Y type.     

Differenzierendes Kaulquappen-Fressen durch Molche

Summary Differential predation on tadpoles by newts (Triturus). 4 EuropeanTriturus species (T. alpestris, T. cristatus, T. helveticus, T. vulgaris) feed upon the tadpoles of the following Anura species which occur in sympatry with the newts:Rana esculenta, R. temporaria andBombina variegata. OnlyTriturus cristatus prey also upon the tadpoles ofBufo bufo andB. calamita. Triturus alpestris, T. helveticus andT. vulgaris do not eat anyBufo tadpoles. Even larvae ofTriturus alpestris prey upon tadpoles ofRana esculenta, R. ridibunda andBombina variegata but avoid tadpoles ofBufo calamita.

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Mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung.     

Biomedicine and diseases: the Klippel-Trenaunay syndrome, vascular anomalies and vascular morphogenesis

Vascular morphogenesis is a vital process for embryonic development, normal physiologic conditions (e.g. wound healing) and pathological processes (e.g. atherosclerosis, cancer). Genetic studies of vascular anomalies have led to identification of critical genes involved in vascular morphogenesis. A susceptibility gene, VG5Q (formally named AGGF1), was cloned for Klippel-Trenaunay syndrome (KTS). AGGF1 encodes a potent angiogenic factor, and KTS-associated mutations enhance angiogenic activity of AGGF1, defining ‘increased angiogenesis’ as one molecular mechanism for the pathogenesis of KTS. Similar studies have identified other genes involved in vascular anomalies as important genes for vascular morphogenesis, including TIE2, VEGFR-3, RASA1, KRIT1, MGC4607, PDCD10, glomulin, FOXC2, NEMO, SOX18, ENG, ACVRLK1, MADH4, NDP, TIMP3, Notch3, COL3A1 and PTEN. Future studies of vascular anomaly genes will provide insights into the molecular mechanisms for vascular morphogenesis, and may lead to the development of therapeutic strategies for treating these and other angiogenesis-related diseases, including coronary artery disease and cancer.Received 24 November 2004; received after revision 21 January 2005; accepted 2 March 2005     

On the usefulness of macroeconomic forecasts as inputs to forecasting models

A forecasting model for y_t based on its relationship to exogenous variables (e.g. x?_t) must use x?_t, the forecast of x?_t. An example is given where commercially available x?_t's are sufficiently inaccurate that a univariate model for y_t appears preferable. For a variety of types of models inclusion of an exogenous variable x?_t is shown to worsen the y_t forecasts whenever x?_t must itself be forecast by x?_t and MSE (x?_t) > Var (x?_t). Tests with forecasts from a variety of sources indicate that, with a few notable exceptions, MSE (x?_t) > Var (x?_t) is common for macroeconomic forecasts more than a quarter or two ahead. Thus, either:

• (a) available medium range forecasts for many macroeconomic variables (e.g. the GNP growth rate) are not an improvement over the sample mean (so that such variables are not useful explanatory variables in forecasting models), and/or
• (b) the suboptimization involved in directly replacing x?_t by x?_t is a luxury that we cannot afford.

     

Mitochondrial DNA variation in social wasps (Hymenoptera,Vespidae)

Summary Patterns of restriction fragment length polymorphisms (RFLP) of European Vespinae were more similar within genera than between them. Distance trees were constructed that support the hypothesis of monophyly of the generaVespula andDolichovespula. Within the genusVespula, V. germanica was more closely related toV. rufa than toV. vulgaris. The position of the genusVespa remained uncertain due to the precision limits of the RFLP technique.     

Monogenic determinants of familial Alzheimer's disease: presenilin-2 mutations

Presenilin-2 (PS2) is one of three genes [amyloid precursor protein (APP), presenilin-1 (PS1) and PS2] shown to cause familial Alzheimer's disease (FAD), and is highly homologous to PS1. Currently demonstrated functions of PS2 include interactions with APP and Aβ, and participation in apoptotic pathways. PS2 FAD mutations influence APP processing in a manner predicted to promote amyloid formation and also enhance the proapoptotic effect of wild-type PS2. Other possible functions of PS2 are related to its homology to Notch pathway genes in Caenorhabditis elegans, suggesting it may have a developmental role. PS2-associated AD is the most reminiscent of the sporadic form of the disease in terms of older age of onset and longer disease duration. Since PS2 mutations are incompletely penetrant and age of onset in carriers is highly variable (40 – 88 years), elucidation of PS2 mechanisms may reveal factors which modify AD and are therapeutically relevant to sporadic AD.     

RTA2 is involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in Candida albicans

The calcineurin pathway has been reported to be essential for the development of azole resistance in Candida albicans. The depletion or ectopic over-expression of RTA2 increased or decreased susceptibility of C. albicans to azoles, respectively. CaCl₂- induced activation of the calcineurin pathway in wildtype C. albicans promoted resistance to azoles, while the Ca ²⁺ chelator (EGTA), calcineurin inhibitors (FK506 and cyclosporin A) and the deletion of RTA2 blocked the resistance-promoting effects of CaCl₂. Furthermore, we found that RTA2 was up-regulated in a calcineurin-dependent manner. The depletion of RTA2 also made the cell membrane of C. albicans liable to be destroyed by azoles and RTA2 over-expression attenuated the destroying effects. Finally, the disruption of RTA2 caused an increased accumulation of dihydrosphingosine (DHS), one of the two sphingolipid long-chain bases, by decreasing release of DHS. In conclusion, our findings suggest that RTA2 is involved in calcineurin-mediated azole resistance and sphingoid long-chain base release in C. albicans. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 14 July 2008; received after revision 29 August 2008; accepted 16 September 2008     

Simple integrated rate equations for reversible bimolecular reactions

Summary If the complete rate equations for reversible, one-step, bimolecular reactions are written withP _e–P as the concentration variable (whereP _e is the equilibrium, andP is the instantaneous, product concentration), the 3 possible stoichiometries can be reduced to a single straightforward differential equation. This can be solved very economically. For each stoichiometry, weret is time,k ₁ is the forward rate constant,K _e is the equilibrium constant, and P isP–P _o. The termsP _c–P _o andD+P _c–P _o are the physically possible and physically impossible roots of the quadratic equation forP _e–P _o in terms of the initial concentrations andK _c.D is the discriminant in this equation. All 3 quantities can be calculated if the equilibrium constant is known. A plot oft against ln{[1–P/(D+P _c–P _o)]/[1–P/(P _c–P _o)]} should be a straight line for any second order reaction. For each stoichiometry,P _c–P _o approachesA _o, the initial concentration of the first reactant, as the equilibrium constant increases. When a second reactant is present,D+P _e–P _o approachesB _o. The limiting equation is then that of an irreversible bimolecular reaction. For AP+Q,D approaches –K _e as the equilibrium constant becomes large, and the value of the second logarithmic term in the integrated equation approaches zero. The limiting equation is that of an irreversible, unimolecular reaction.Acknowledgments. I thank Dr. Athel Cornish-Bowden for many helpful discussions. This work was partially supported by a grant from Utah State University.     

Short-range linkage relationships, genomic organisation and sequence comparisons of a cluster of five HSP70 genes in Fugu rubripes

Twelve cosmids containing sequences resembling genes encoding members of the 70-kDa heat-shock protein family, HSP70, have been isolated from Fugu rubripes. They can be broadly divided into three groups of overlapping cosmids. Restriction analysis and sequencing of one set of five cosmids have revealed five intronless Fugu HSP70 genes spanning 42 kb, arranged in a combined head-to-head, tail-to-tail and head-to-tail orientation. The levels of DNA and amino acid identity are very high with respect to one another, and are most similar to HSP70 sequences linked to the major histocompatibility complex (MHC) region in other species. Putative heat-shock consensus elements are identified. Non-HSP70 sequences with homology to known genes have been found physically linked to this Fugu HSP70 cluster: the Drosophila melanogaster SOL gene, the Drosophila melanogaster nemo gene, the Caenorhabditis elegans T17E9.1 gene and the sequence encoding the serine protease domain. The linkage relationships described here so far bear no resemblance to those of HSP70 in other organisms. Convergence of mammalian HSP70 and MHC class I and II loci probably occurred after fish had diverged. Received 17 November 1998; received after revision 25 February 1999; accepted 26 February 1999     

Temporal Aggregation in Dynamic Linear Models

One important aspect concerning the analysis and forecasting of time series that is sometimes neglected is the relationship between a model and the sampling interval, in particular, when the observation is cumulative over the sampling period. This paper intends to study the temporal aggregation in Bayesian dynamic linear models (DLM). Suppose that a time series Y_t is observed at time units t and the observations of the process are aggregated over r units of time, defining a new time series Z_k=Σ^r_i=1Y_rk+i. The relevant factors explaining the variation of Z_k can, and in general will, be different, depending on how the sampling interval r is chosen. It is shown that if Y_t follows certain dynamic linear models, then the aggregated series can also be described by possibly different DLM. In the examples, the industrial production of Brazil is analysed under various aggregation periods and the results are compared. © 1997 John Wiley & Sons, Ltd.     

Unstable genetic system inDrosophila melanogaster: I. Instability at theCinnabar locus

Summary A mutant strain containing acinnabar allele (cn ^rbr ,rojo brillante) is reported, that produces wild-type revertants at thecinnabar (cn) locus. Incn ^rbr /cn heterozygotes the rate of mutation is highly increased. The presence of a mutator agent acting premeiotically is indicated.D.L. Lindsley and E.H. Grell, Genetic variations ofDrosophila melanogaster. Carnegie Institution of Washington, Washington, 1968; Publication No. 627.     

Mating attempts between the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L. (Lepidoptera: Arctiidae), involve a common sex pheromone composition

It has been suggested that a common sex pheromone composition may account for interspecific sexual interactions observed with certain moths in the Arctiidae. In this study, it is demonstrated that the sex pheromones released by females of the Scarlet Tiger Moth,Callimorpha dominula L., and the Cinnabar Moth,Tyria jacobaeae L., have similar activities and elute at the same retention time on analysis by coupled gas chromatography (GC)-electrophysiology with males from each species. Peak enhancement on GC, chiral GC and coupled GC-mass spectrometry using authentic compounds show that the sex pheromone for bothC. dominula andT. jacobaeae is (3Z,6Z,9S,10R)-9,10-epoxyheneicosa-3,6-diene.