Karyotypic races of the common shrew (Sorex araneus L.) from northern Poland

Karyotypic races of the common shrew which differed with respect to the combinations of chromosome arms in certain 2-armed autosomes were distinguished in Poland. Two eastern races with the arm combination ik, and one western race with the arm combination hi in the third pair of autosomes were established. In the contact area of these chromosomal forms, the fourth karyotypic race with the arm combination hk was found.     

Chromsome aberrations in cattle raised on bracken fern pasture

Summary Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.Acknowledgments. We are grateful to Dr F. J. Benesi, Dr J. L. Guerra and Dr I. L. Sinhorini for performing some of the clinical and pathological analyses; O. P. Ferraz, L. A. Tadeu Dias, L. F. Feitosa and A. M. N. Paiva for technical assistance; and to Dr N. H. C. Castro and Dr C. de Araujo Peres for critical and statistics review, respectively. Research was supported by CNPq FAPESP and CAPES.     

Telocentric chromosomes in pearl millet,Pennisetum typhoides

Summary InPennisetum typhoides S. and H., a new karyotype was found with 13 normal chromosomes and 2 stable telocentric chromosomes, which represent 1 arm each of a submetacentric chromosome.The authors are thankful to Dr.J. V. Pantulu, Professor of Cytogenetics, for guidance and encouragement and to Dr.V. Manga, for helpful discussion. They express their thanks to the U. G. C. (PSRLNR) and to the C. S. I. R. (MVSR and INR) for the award of Junior Research Fellowships.     

On the mechanism of killing ofTrypanosoma cruzi by human polymorphonuclear leukocytes

Summary The temperature-dependence of some processes involved in the killing of sensitizedT. cruzi epimastigotes by human polymorphonuclear leukocytes (PMN) was determined. The rate of the reactions was related to the temperature of incubation according to the Arrhenius equation and the apparent energies of activation (Ea) were calculated. The Ea values separated these complex reactions into two groups: one with Ea of about 10 kcal/mol for the phagocytosis of the parasites and the release of lysosomal enzymes by PMN, and the other with Ea of about 22 kcal/mol for the cytotoxicity against sensitizedT. cruzi, the rate of oxygen consumption by PMN, and the lysis of the parasites with added hydrogen peroxide.This work was supported by research grants from CONICET and SUBCYT, Argentina, and UNDP/Word Bank/WHO Special Programme for Research and Training in Tropical Diseases. The author wish to thank Dr I. Reisin, Dr. A. Boveris and Dr M.M.E. de Bracco for their helpful discussion.     

Cytogenetic observations inCeratitis capitata

Summary The 2n=10+XX/XY complement ofC. capitata includes3 pairs of metacentric and 2 pairs of submetacentric autosomes; theX andY chromosomes are acrocentrics. The sex chromosomes do not pair somatically during mitotic prophase, and, using the C-banding technique, band more extensively than the autosomes. Male meiosis may be achiasmate; there is no leptotene, zygotene or diplotene.Material kindly supplied by Dr.D. A. Lindquist, I.A.E.A./FAO Vienna, Austria.     

Sex determination in mammals — Before and after the evolution of SRY

Therian mammals (marsupials and placentals) have an XX female: XY male sex chromosome system, which is homologous to autosomes in other vertebrates. The testis-determining gene, SRY, is conserved on the Y throughout therians, but is absent in other vertebrates, suggesting that the mammal system evolved about 310 million years ago (MYA). However, recent work on the basal monotreme mammals has completely changed our conception of how and when this change occurred. Platypus and echidna lack SRY, and the therian X and Y are represented by autosomes, implying that SRY evolved in therians after their divergence from monotremes only 166 MYA. Clues to the ancestral mechanism usurped by SRY in therians are provided by the monotremes, whose sex chromosomes are homologous to the ZW of birds. This suggests that the therian X and Y, and the SRY gene, evolved from an ancient bird-like sex chromosome system which predates the divergence of mammals and reptiles 310 MYA. Received 4 March 2008; received after revision 22 April 2008; accepted 3 June 2008     

Effect of fungal staling growth products on colony interaction amongRhizoctonia solani Kuhn and some potential rhizosphere fungi

Summary Colony interactions betweenRhizoctonia solani Kuhn: a root pathogen ofLycopersicon esculentum Mill and some dominant rhizosphere fungi were assessed in vitro in virgin and staled agar to examine their antagonistic ability and tolerance to antagonism. The range of inhibition ofR. solani varied widely in competition with some of the antagonists.Acknowledgments. I would like to express my appreciation to Dr R. S. Dwivedi for encouragement and CSIR for financial assistance.Address for reprint request: Dr D.K. Arora, Old G/14, Jodhpur Colony, Banaras Hindu University, Varanasi 221005, India.     

Heterochromatization in opossum,Didelphys virginiana

Conclusion Somatic heterochromatization of the opossum,D. virginiana, was studied from prophase and tritiated thymidine-labeled metaphase chromosome preparations. In both sexes of this mammal, a number of prophase autosomes and the sex chromosomes were observed displaying deeply stained condensed areas. These chromosomal areas were interpreted as evidence for heterochromatization. The extent of heterochromatization in the opossum was found much greater in certain autosomes than either theX orY chromosome alone. This assertion that some opossum autosomes possess more heterochromatin than the sex chromosomes was supported by data collected on the terminal labeling patterns of the chromosomes. Metaphase autoradiographs prepared from cultured leucocytes of the animals unequivocally suggested that certain opossum autosomes completed replication later than the sex chromosomes. If one assumes that there is heterochromatin in the autosomes, as the evidence suggests, then it merely becomes a question as to what block of heterochromatin replicates last — a phenomenon that is probably size dependent.

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Résumé L'héterochromatisation somatique de l'opossum (Didelphys virginiana) a été étudiée sur des préparations de chromosomes aux stades de la prophase et de la métaphase, la thymidine ayant été utilisée comme marqueur. Dans les 2 sexes de ce mammifère de nombreux autosomes et les chromosomes sexuels montrent, à la prophase, des plages denses fortement colorées. Ces plages chromosomiales ont été interprétées comme un signe évident d'héterochromatisation. L'héterochromatisation est beaucoup plus accentuée dans certains autosomes que dans les chromosomesX ouY. Les autoradiographies de stades métaphasiques dans des préparations effectuées de leucocytes en cultures suggèrent d'une façon non équivoque que certains autosomes de l'opossum achèvent leur réplication plus tardivement que les chromosomes sexuels. Si l'on assume que l'héterochromatine est présente dans les autosomes, comme le démontrent nos observations, il semble évident que l'héterochromatine autosomale a un rôle significatif dans le développement.

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Supported in part by Baylor University College of Medicine General Research Grant (No. P-13) and grants from the James Picker Foundation and the Texas Heart Association. The auther wishes to thank Dr.W. Hill for his help at the vivarium and MissMarion Gay and MissShirley Powell for technical assistance. The editorial assistance of MissMarilyn Morningstar is also appreciated.     

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.     

Cytogenetic studies of Hynobiidae (Urodela). IX. Karyological characteristics ofHynobius abei Sato by means of R-and C-banding

Summary Chromosomal characteristics of the salamander speciesHynobius abei, from Ohimya (Kyoto) were revealed by the techniques of R-and C-banding. The karyotype ofH. abei was characterized by the shortness of an R-negative (C-positive) band in the terminal region of the long arm of chromosome 2 and a band encompassing the whole short arm of chromosome 10. These two bands inH. abei were the shortest among those of the variousHynobius species that have been examined. Otherwise no differences could be detected betweenH. abei and seven other pond-type species ofHynobius (2n=56) in terms of the banding patterns of 18 specifically identifiable pairs of their chromosomes.     

Cytogenetic observations on a monosomic inSesbania macrocarpa Muhl. (Leguminosae)

Summary Karyotypic analysis of a spontaneous monosomic plant isolated from a population ofSesbania macrocarpa (2n=4x=24) revealed that one chromosome of the smallest set was missing. The absence of this chromosome caused a deleterious effect on the meiotic system of the plant, resulting in total male and female sterility. The origin of the species in this context is discussed.Thanks are due to Dr B. D. Patil, Indian Grassland and Fodder Research Institute for facilities and to Dr S. K. Gupta, for valuable suggestions.     

Chiasmate meiosis in roaches. II. Meiosis in Blatella supellectilium Serv.

Summary In the cockroach, Blattella supellectilium Serv., meiosis in the male is of a normal, chiasmatic type, with an average chiasma frequency of 1.3 per bivalent (2n=22+XO).This paper is dedicated to my Professor and Principal, Dr J.C. Uttangi, who retired recently.I express with pleasure sincere thanks to my colleague Dr R. M. Patil for his valuable suggestions during the course of this work.     

Zur Polymorphie eines Chromosoms innerhalb von Populationen des LaufkäfersCarabus auronitens Fabr

Summary C. auronitens has 26 autosomes (2n), from which one pair — calledA-chromosomes — is relatively long.A-chromosomes consist of an euchromatic and a heterochromatic arm. In 63% of the individuals, theA-chromosomes are intraindividually anisomorph with regard to the length of their heterochromatic arm. According to its length, this arm shows 0–3 secondary constrictions. Hence there are at least 4 different forms of theA-chromosome.     

Chiasmate type of meiosis in the roachNauphoeta cinerea (Oliver) (Fam: Blattidae)

Résumé Nauphoeta cinerea est un des Cafards chez lesquels le chiasma de la méiose a été nettement observé. Ce cas vient à l'appui de l'assertion deSuomalainen selon laquelle des chiasmas se présenteraient sous une forme soit «cachée» soit «visible» chez tous les Cafards. La «méiose sans chiasma» queJohn etLewis supposent existes au moins chezP. americana n'est pas non plus confirmée par nos recherches.

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I wish to thank one of the research scholars of the Department, Mr. V. L.Kallapur, for sparing readily some specimens of the roach for my work. Constructive criticisms by my colleague Dr. R. M.Patil are also acknowledged.     

Occurence of diploid drones in a neotropical bumblebee

Zusammenfassung Mutter-Sohn-Kreuzung bei der südamerikanischen HummelBombus atratus Franklin ergab diploide Männchen mit normalen Arbeiterinnen im Verhältnis von 3 zu 1. Tur Interpretation des genetischen Mechanismus wurden 2 geschlechtsgebundene Loci angenommen, als bisher angenommen wurde, was für einen älteren Mechanismus bei Apiden spricht.

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This study was made possible by a grant of the State of São Paulo Research Foundation (FAPESP).

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Acknowledgment. I would like to thank Dr.W. E. Kerr, Dr.R. Zucchi and Dr.S. F. Sakagami for their excellent assistance during the course of this investigation as well during the translation. I also would like to thank Dr.R. H. Crozier for his suggestions and comments and I extend my thankfulness to professorsJ. Chaud Netto andZ. Silveira.     

Random chromosome breakage by colchicine inViscum fischeri (Loranthaceae)

Summary When the shoot-tips ofViscum fischeri Engl. were treated with various concentrations of colchicine for different lengths of time, it was found that in this plant chromosome breakage was not localized to centromeric region as reported in other plants. InV. fischeri chromosome breakage occurred at random (simulating X-ray-induced fragmentation). The percentage of breakage increased linearly with respect to time at concentrations 0.1, 0.2, 0.3% but parabolically at 0.5%.Acknowledgment. The authors are grateful to Dr M. A. Hannan of NRC, Ottawa, Canada, for his helpful criticism and suggestions, and to Professor S. K. Imbamba, Chairman, Dept. of Botany, University of Nairobi for laboratory facilities.     

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).     

Torus shaped bands at the 2R telomere region and at the region 68 of the salivary gland chromosomes ofDrosophila auraria

Summary The telomere of the 2R arm of the salivary gland chromosomes ofD. auraria exhibits a definite toroidal structure in routine squashed preparations, stained either by propionic orcein-carmine or by fluorescent dyes. There is evidence that a band (or bands) of region 68 (possibly homologous to that ofD. melanogaster) of the 3L chromosome arm also exhibits a toroidal structure. These toroids are associated with heterochromatin, but it is not certain that they are themselves heterochromatic.Acknowledgments. This work was supported by a grant from Volkswagenwerk-Stiftung to C.D.K. The outstanding technical assistance of Ms G. Karamanlidis is acknowledged.     

Genetic analysis of modifier variability inDrosophila subobscura

Summary The previously detected modifier variability acting on the expression of the Bare (Ba) locus inDrosophila subobscura is demonstrated to be due to polygenes situated along the chromosome O. From crosses between isogenic lines of high and low modifier effect we ascertained the presence of approximately 5 modifier loci.We are grateful to Dr M. Green for valuable comments on the experimental design used in this paper.