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.     

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     

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.     

Beta-carotene affects gene expression in lungs of male and female <Emphasis Type="Italic">Bcmo1</Emphasis><Superscript>−/−</Superscript> mice in opposite directions

Molecular mechanisms triggered by high dietary beta-carotene (BC) intake in lung are largely unknown. We performed microarray gene expression analysis on lung tissue of BC supplemented beta-carotene 15,15′-monooxygenase 1 knockout (Bcmo1 ^−/−) mice, which are—like humans—able to accumulate BC. Our main observation was that the genes were regulated in an opposite direction in male and female Bcmo1 ^−/− mice by BC. The steroid biosynthetic pathway was overrepresented in BC-supplemented male Bcmo1 ^−/− mice. Testosterone levels were higher after BC supplementation only in Bcmo1 ^−/− mice, which had, unlike wild-type (Bcmo1 ^+/+) mice, large variations. We hypothesize that BC possibly affects hormone synthesis or metabolism. Since sex hormones influence lung cancer risk, these data might contribute to an explanation for the previously found increased lung cancer risk after BC supplementation (ATBC and CARET studies). Moreover, effects of BC may depend on the presence of frequent human BCMO1 polymorphisms, since these effects were not found in wild-type mice.     

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.     

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.     

Un nouveau type de détermination chromosomique du sexe chez les mammifèresEllobius lutescens Th. etMicrotus (Chilotus) oregoni Bachm. (Muridés-Microtinés)

Summary (1)Ellobius lutescens andMicrotus oregoni show the same type of sex-chromosomes. The diploid number is odd in both sexes, seventeen.(2) The odd element ofEllobius is morphologically alike in the male and in the female. InM. oregoni, the odd element of the male is acrocentric, that of the female metacentric.(3) Following a hypothesis ofWhite, it seems very probable that the heterochromosome of the male is built of the primitiveY (short arm) and the primitiveX (long arm) linked together. In the female of the same species (M. oregoni), the sex-chromosome represents both theX fused together.(4) Only the half of the Zygotes may develope, the other half being lethal.(5) The close kinship betweenEllobius andM. oregoni is certain, a parallel evolution appearing as highly improbable.     

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.     

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.     

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.     

Mikrobiologische Spaltung razemischer Steroide. Synthese vond-Aldosteron

Summary A racemic intermediate in the total synthesis ofd, l-aldosterone, thed, l-20-oxo-pregnene derivative I, was converted by incubation with a mold hydroxylating in the 21-position into thed-20-oxo-21-hydroxy-pregnene derivative II, whereas thel-antipode of the starting material remained unchanged. This stereospecific microbiological reaction, comprising a separation of racemic modifications, represents the last remaining step in the synthesis of naturald-aldosterone.Other microbiological conversions of racemic steroids, dehydrogenation and hydrogenation, were also shown to proceed only with thed-enantiomer, leaving thel-form of thed, l-substrate intact.The advantages of this new microbiological method for the resolution of racemic modifications during the total synthesis of steroids are discussed.     

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     

Protein O-GlcNAcylation regulates Drosophila growth through the insulin signaling pathway

Modification of nuclear and cytosolic proteins by O-linked N-acetylglucosamine (O-GlcNAcylation) is ubiquitous in cells. The in vivo function of the protein O-GlcNAcylation, however, is not well understood. Here, we manipulated the cellular O-GlcNAcylation level in Drosophila and found that it promotes developmental growth by enhancing insulin signaling. This increase in growth is due mainly to cell growth and not to cell proliferation. Our data suggest that the increase in the insulin signaling activity is mediated, at least in part, through O-GlcNAcylation of Akt. These results indicate that O-GlcNAcylation is one of the crucial mechanisms involved in control of insulin signaling during Drosophila development.     

Multiple phosphoglucomutase alleles in two species ofMansonia mosquito

Summary Multiple phosphoglucomutase (E.C.2.7.5.1) alleles are found in the mosquitoesMansonia crassipes andM. uniformis. The present study reveals 4Pgm alleles, of whichPgm ^B andPgm ^C are common to both species whilePgm ^A is present only inM. crassipes andPgm ^D only inM. uniformis. The frequencies in both species accord well with Hardy-Weinberg expectations. The most frequent allele is that controlling a phenotype with an intermediate electrophoretic mobility, viz.Pgm ^B inM. crassipes andPgm ^C inM. uniformis.This work is supported in part by a University of Malaya research grant to the senior author.     

Caryotypes de quelques hybrides interspécifiques dePitymys (Mammalia,Rodentia)

Summary The Robertsonian polymorphism ofPitymys subterraneus involves only 1 pair of metacentric autosomes. The crosses of forms with 52, 53 and 54 chromosomes do not show any differences in their reproductive rate. So a single autosome trivalent does not affect the fecondity. Many hybrids have been obtained betweenP. subterraneus (2N=52 or 54) andP. multiplex (2N=48) with 50 or 51 chromosomes, respectively. Even with a heterogenous karyotype they are not entirely sterile. 2 progeny were produced from back-crosses. The 2 parental species seem to result from recent speciation. Only fecondation or embryogenesis occurs in crossingP. duodecimcostatus withP. subterraneus orP. multiplex. The chromosome complement of 1 hybrid embryo ofP. duodecimcostatus (2N=62)×P. multiplex (2N=48) has been studied showing 55 chromosomes.P. duodecimcostatus appears to belong to a more distant evolutionary group.     

Alexis Fontaine's ‘Fluxio-differential method’ and the origins of the calculus of several variables

Alexis Fontaine des Bertins (1704–1771) was the first French mathematician to introduce what we would now regard as results in the calculus of several variables. One example is Fontaine's theorem nF = (?F/?x)x + (?F/?y)y of 1737 for homogeneous expressions F of degree n in x and y. Many years later Fontaine indicated this particular result to have been ‘a continuation of the method of solution’ introduced by him in 1734 to solve the problem of the tautochrones. It is tempting to disregard this announcement, since the method applied to the tautochrones was a method of variations and not manifestly an exercise in the calculus of several variables. Do we have just another case of a mathematician's confusion about the origins of his earlier work? In this paper I describe Fontaine's possible intentions in his remarks.