Electrophoretic variation in esterases in 3 wild-type and respective mutant strains ofAspergillus flavus

Summary Wild-type strains and auxotrophic mutants ofAspergillus flavus, differing regarding aflatoxin production, were tested for esterases isozymes. Esterases variation was found in all strains used, and a possible correlation between the pattern of esterase bands and aflatoxin production is suggested.Acknowledgment. The authors are thankful to the National Council for the development of Science and Technology (CNPq) and Assistance to Research for São Paulo State (FAPESP) for financial assistance.     

Genotypic differences between the mouse adenovirus strains FL and K87

Summary Restriction endonuclease analysis was used to compare the genome of mouse adenovirus (MAd) strains FL and K87. Large differences were found between theKpn I,PaeR7,Pvu I,Sal I andSma I restriction profiles of the prototype strains. MAd-FI and MAd-K87 thus represent two distinct species of mouse adenovirus.This work was supported by grants from the Fonds pour la formation de chercheurs et l'aide à la recherche and the Natural Sciences and Engineering Research Council of Canada.     

Kinetics and Na-dependence of riboflavin absorption by intestine in vivo

Conclusion The transport of riboflavin across the intestinal mucosa is certainly not by a system of passive diffusion. It necessitates the presence of a specific transporter in the membrane, thus explaining saturation kinetics noted. The transport is dependent on the presence of Na⁺ in the perfusion medium. However, it is not as yet possible to say whether transport is against an electrochemical gradient or a system of facilitated diffusion with simple equilibrium of concentrations extra-and intra-cellular.

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Résumé L'absorption intestinale de la riboflavine est mesurée in vivo par perfusion d'un segment proximal du jéjunum chez le rat. Le transport de la vitamine à travers la muqueuse intestinale suit une cinétique de saturation (K _t =3M; V _max =0,26 nMole par min et par g de tissu frais). Il est fortement réduit (de 40 à 50%) lorsqu'on substitue au NaCl isotonique du milieu de perfusion du mannitol ou du LiCl isotoniques.

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Acknowledgements. We should like to thank Prof.B. Blanc who made possible the completion of this work, Prof.W. Wilbrandt and Prof.G. Semenza for their advice and criticism. The work was supported by the Foundation pour la Recherche Nutritionelle (financed by Zyma S. Y., Nyon and Union Laitière Vaudoise, Lausanne).     

Endocytosis and inositol hexakisphosphate levels inras transformants ofDictyostelium discoideum amoebae

Summary Fluid-phase pinocytosis kinetics and lysosomal enzyme secretion parameters were measured inDictyostelium discoideum amoebae constructed from strain AX3 by transformation with a multicopy plasmid carrying either a normalras gene (ras-Gly12), a mutatedras gene (ras-Thr12) or by the vector carrying the geneticin resistance gene only (pDNEO2). It was found that the pinocytosis rate and extent as well as the lysosomal enzyme secretion were slightly different in the three strains. These changes, however, were related to minor modifications of the cellular volumes. The overall concentration of inositol hexakisphosphate was similar in the three strains.This work was supported in part by a grant from the Ligue Nationale Française contre le Cancer (n^o 880258) to MS, and by a grant from the Fonds National Suisse de la Recherche Scientifique (No. 3.623-087) to CR.     

Mutagenicity and toxicity of chloroethylene oxide and chloroacetaldehyde

Summary Exposure of severaltrp-auxotrophicEscherichia coli strains, carrying base0pair substitutions, to chloroethylene oxide or chloroacetaldehyde (two metabolites of vinyl chloride) increased the mutation frequency to tryptophan prototrophy. Strong cytotoxic and mutagenic effects were observed with 2.5 mM chloroethylene oxide, while a higher concentration of chloroacetaldehyde (100 mM) exhibited a mutagenic effect which was 400 times lower.I am grateful to Prof. G. Michel, Laboratoire de Biochimie Microbienne, and to Dr H. Bartsch, International Agency for Research on Cancer, for the support of this work. I wish to thank Dr F. Besson-Simien and Dr A. Barbin for their collaboration.     

Experiments on sexual isolation between Chilean and European strains ofDrosophila subobscura

Summary Males and females of Chilean strains ofDrosophila subobscura exhibit a pronounced tendency toward homogamic mating. This tendency shows a clear relation to the distance between the geographic localities from which the respective strains came. Nevertheless, when the Chilean flies are confronted with European strains, the ethological isolation is observed in some cases but not in others, depending on the geographic origin of the strains.Acknowledgments. This work has been partially supported by grants from the Univ. of Chile (Project B 729-8345) and PNUD/UNESCO (RLA 78/024). We are most grateful to Prof. D. Sperlich of the University of Tübingen who provided theD. subobscura strains from Tübingen and Sicily, and Prof. A. Prevosti from the University of Barcelona and R. de Frutos from the University of Valencia who provided the strains of Mallorca and Almería. We are finally obliged to Mr E. Zárate for his technical assistance.     

Radioprotective effect of hydrocortison and prednisolon on theVicia faba equina

Résumé Avec leVicia faba test, nous avons pu démontrer l'effet radioprotecteur de l'hydrocortisone et de la prednisolone. L'effet radioprotecteur de la prednisolone est grosso modo, 4 fois plus important que celui de l'hydrocortisone.

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This work was made possible by a subsidy from the Swiss National Fund for Scientific Research.     

Frequency distribution ofTrypanosoma cruzi in macrophages from resistant and susceptible strains of mice

Summary The frequency distribution ofTrypanosoma cruzi inside macrophages from normal of chronically infected resistant and susceptible mice obeys a negative binomial type of distribution. This implies that an aggregating mechanism operates inT. cruzi: macrophage interaction.Acknowledgments. We thank Dr Sylvio T. Torres for providing the inbred strains of mice. The work was supported by the Brazilian Research Council (CNPq) and the Financiadora de Estudos e Projectos (FINEP).     

Interaction between 6-hydroxydopamine and rhodopsin in vivo in the rat retina

Résumé Nous avons observé que l'injection de la 6-hydroxydopamine dans l'humeur vitrée des rats adaptés à la lumière bloquait le rétablissement de la sensibilité rétinale pendant l'adaptation à l'obscurité subséquente au traitement. Il est possible que cette observation soit une conséquence de la réaction du produit de l'oxydation de la 6-hydroxydopamine avec les groupes nucléophiliques de la rhodopsine.

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This study was partially supported by Postdoctoral Training Grant No. MH 10965 to S.F.P. and by Eli Lilly Co., Research to Prevent Blindness, Inc., and NSF No. GB-39853 to L.T.G. Samples of 6-aminodopamine were kindly supplied by Drs.R. N. Adams (University of Kansas, Lawrence, Kansas) andE. L. Engelhardt (Merck Sharp and Dohme Res. Labs. West Point, Pa.) andp-quinone by Dr.P. A. Wehrli (Hoffmann-La Roche, Nutley, New Jersey). The authors thank Mr.L. Tomey for excellent technical assistance.     

Effects of glycine and serine on serine hydroxymethyltransferase levels in logarithmic cultures ofNeurospora crassa wild type andSer-1 mutant

Résumé Dans un milieu minimal la glycine et la sérine, ajoutées en concentrations physiologiques, augmentent le taux de la sérine-hydroxyméthyltransférase durant la croissance logarithmique duNeurospora crassa. La glycine influence également la synthèse de cet enzyme chez le mutantSer-1 deNeurospora. Ainsi la glycine exogène exerce une régulation de la sérine-hydroxyméthyltransférase et cet enzyme joue un rôle possible dans la synthèse de la sérine dans cet organisme en phase logarithmique de croissance.

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Acknowledgements. This investigation was supported by grant No. 3.540.71 from the Fond National Suisse de la Recherche Scientifique. E.A.C. was the recipient of a National Research Council of Canada travel fellowship. The authors thank MlleMartine Gourjon for excellent technical assistance.     

Constitutive heterochromatin and nucleolus organizer region in the knifefish,Apteronotus albifrons (Pisces,Apteronotidae)

Summary The C-banding and silver staining of the chromosomes of the knifefishApteronotus albifrons (2n=24), demonstrated the presence of constitutive heterochromatin in the centromeric region of every chromosome, except pair 4, where the entire long arm was darkly stained, the silver stain positive nucleolus organizer region (NOR) being embedded in it.The authors are grateful to Dr Sen Pathak (University of Texas System Cancer Center at Houston, Texas, USA) and Dr Yatiyo Yassuda (Universidade de São Paulo, São Paulo, Brasil) for their suggestions. This study was supported in part by grants of the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq).     

Bulk staining of ovules and ovaries to note the percentage of well-organized embryo sacs in sterile and semi-sterile plants utilized for breeding purpose

Résumé La maculation massive des ovaires et ovules d'Oryza sativa L. a été faite avec du vert rapide et de alcool:xylol (1:1) par étapes. Après section il fut possible de noter le pourcentage des sacs embryonnaires viables et non-viables plus particulièrement dans des plantes stériles et semistériles. Ce procédé peut donner aux planteurs des directives dans leurs expériences d'élevage. Il a permi aussi de localiser les phases exactes de l'avortement.     

Allele-specific PCR reveals thatCYP6D1 is on chromosome 1 in the house fly,Musca domestica

A cytochrome P450, termed P450lpr, is the major P450 responsible for pyrethroid resistance in the Learn-PyR (LPR) strain of house fly. Recently, the putative gene (CYP6D1) coding for P450_lpr has been sequenced from the LPR and aabys strains of house fly. Allele-specific polymerase chain reaction (ASPCR) was used for linkage group analysis with backcross progeny from the wild type LPR strain and a multiple marker strain (aabys). We found thatCYP6D1 is linked to chromosome 1. The possible role of regulatory or modifying genes responsible for elevated P450_lpr expression is discussed in relation to the chromosomal linkage ofCYP6D1.     

A possible duplication in theX chromosome of man

Résumé La morphologie du chromosomeX humain pendant la prophase I — comparable à celle qui a été décrite pour 8 espèces de primates — suggère l'existence d'un «crossing over» dans le chromosomeX de l'homme, du à un dédoublement possible de ce chromosome, résultant du transfer d'un autosome sur son homologue. Ce serait l'origine des chromosomes sexuels de typeX-Y dans les mammifères.     

Hybridation en laboratoire deMus musculus L. etMus spretus Lataste

Summary 2 species of miceMus musculus brevirostris andMus spretus are sympatric in Southern France and reproductively isolated. However, under laboratory conditions, they breed and give fully viable F1 hybrids. This indicates that premating isolating mechanisms probably occur in nature and have yet to be investigated. Moreover, it now enables us to introduce new genetical markers in laboratory strains.

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Remerciements. Cette étude a été menée à bien avec l'assistance technique de J. Catalan. Nous remercions également N. Pasteur, J. Britton-Davidian ainsi que tous les membres du laboratoire pour leurs commentaires avisés dans la discussion des résultats. Ce travail est supporté financièrement par l'Université de Montpellier II, l'EPHE et le C.N.R.S. (ERA-261 et ATP-souris).     

Chromosomal homology in southern Akodon

Summary Differential staining (G and C) of southern South AmericanAkodon are presented.A. olivaceus, A. longipilis andA. sanborni all have the same karyotype (2n=52, NF=58). A virtually identical band sequence is observed. This situation is interpreted using the canalization model of chromosomal evolution which stresses an optimum karyotype for each adaptive zone. Despite the high degree of conservation of the chromosome structures, the specific status of these species is supported by maintenance of distinctness when they occur in areas of sympatry.The research was partially supported by Proyecto de Investigación I-78-86, Dirección de Investigación, Universidad Austral de Chile and Programa Especial de Citogenética, U. de Chile sede Norte, Santiago, Chile.     

A possible role for histamine in larval growth

Résumé Le rôle possible de l'histamine au cours de la croissance larvaire a été étudié. L'inhibition de l'oxydase des diamines au moyen de l'aminoguanidine, a fortement ralenti la croissance larvaire duTribolium confusum. Cette substance, cependant, ne s'est pas avérée toxique. D'autre part l'inhibition des décarboxylases par le semicarbazide ou le deoxypyridoxine ne modifie pas la croissance sans devenir toxique.     

The letter,the dictionary and the laboratory: translating chemistry and mineralogy in eighteenth-century France

SUMMARY

Eighteenth-century scientific translation was not just a linguistic or intellectual affair. It included numerous material aspects requiring a social organization to marshal the indispensable human and non-human actors. Paratexts and actors' correspondences provide a good observatory to get information about aspects such as shipments and routes, processes of translation and language acquisition (dictionaries, grammars and other helpful materials, such as translated works in both languages), texts acquisition and dissemination (including author's additions and corrections, oral presentations in academic meetings and announcements of forthcoming translations).

The nature of scientific translation changed in France during the second half of the eighteenth century. Beside solitary translators, it also happened to become a collective enterprise, dedicated to providing abridgements (Collection académique, 1755–79) or enriching the learned journals with full translations of the most recent foreign texts (Guyton de Morveau's ‘Bureau de traduction de Dijon’, devoted to chemistry and mineralogy, 1781–90). That new trend clearly had a decisive influence on the nature of the scientific press itself. A way to set up science as a social activity in the provincial capital of Dijon, translation required a local and international network for acquiring the linguistic and scientific expertise, along with the original texts, as quickly as possible. Laboratory results and mineralogical observations were used to compare material facts (colour, odour, shape of crystals, etc.) with those described in the original text. By providing a double kind of validation – with both the experiments and the translations – the laboratory thus happened to play a major role in translation.     

Ultrastructural aspects of nucleolar fibrillar centres in meristematic cells ofAllium cepa

Summary This paper deals with the fine structure of the fibrillar centres of the nucleolus inAllium cepa cells in ultrathin, sections of in vivo fixed roots. The ultrastructural observations have allowed us to consider each nucleolar fibrillar centre as an active zone in the nucleolar chromatin loop, and to propose a possible model for the organization of the different components of the nucleolus within it.Acknowledgments. The author wishes to thank Dr.M. C. Risueño for her valuable comments and discussion. This work has been partially supported by the III Plan de Desarrollo of Spain and by a grant of the Foundation Rodriguez Pascual.