Staphylococcus aureus alpha-toxin-induced pores: Channel-like behavior in lipid bilayers and patch clamped cells

The conductance of pores induced by Staphylococcus aureus -toxin in Lettre cells has been compared to that in bilayers composed of synthetic lipids or Lettre cell membrane constituents. Previously described characteristics of toxin-induced conductance changes in lipid bilayers, namely rectification, voltage-dependent closure, and closure at low pH or in the presence of divalent cations (Menestrina, 1986) are displayed also in bilayers prepared from Lettre cell membranes and in patch clamped Lettre cells. It is concluded that endogenous proteins do not affect the properties of -toxininduced channels significantly and that the relative lack of ion channels in Lettre cells makes them ideal for studies of pore-forming toxins by the patch clamp technique.Dr. Sviderskaya is on leave of absence from the Physiology Institute, University of St. Petersburg, RussiaWe are grateful to Dr. J.P. Arbuthnott and Dr. K. Hungerer for gifts of S. aureus -toxin, to Dr. T.B. Bolton for collaboration with patch clamped cells and to Dr. J.M. Graham for help with the preparation of Lettre cell plasma membranes. This study was supported by the Cell Surface Research Fund, Medical Research Council, Science and Engineering Research Council, UNESCO (Molecular and Cell Biology Network) and The Wellcome Trust.     

Histochemical localization of adenosinetriphosphatase in the testicular and pre-testicular nephridia of the Indian leech Hirudinaria granulosa (Savigny)

Summary Adenosinetriphosphatase has been histochemically demonstrated in the initiallobe cells and the central canal in its first round in the pre-testicular and testicular nephridia of the Indian leech Hirudinaria granulosa. The apical-lobe cells are positive in the pre-testicular and negative in the testicular nephridia. The functional significance of the enzyme at these sites has been discussed.I wish to express my gratitude to Dr. H. B. Tewari, under whose guidance the present work has been carried out. I am also indebted to Dr. M. L. Dhar, Director, Central Drug Research Institute, Lucknow; Dr. P. S. Krishnan, Professor of Biochemistry, University of Lucknow; and Dr. (Miss) Usha Gupta, Department of Pathology, University of Lucknow, for the hospitality which they have accorded me in their laboratories.     

Substrate and inhibitor specificities of the thermostable alcohol dehydrogenase allozymes ADH-71k and ADH-FCh.D. ofDrosophila melanogaster

Purified thermostable alcohol dehydrogenase allozymes ADH-71k and ADH-FCh.D. ofDrosophila melanogaster have been compared with the two common enzyme forms ADH-F and ADH-S. Enzyme kinetic parameters for various primary and secondary alcohols were determined under standard conditions used previously. Both ADH-71k and ADH-FCh.D. show ADH-S-like reaction kinetics andK _m values, due to retrograde evolution at site 214, Pro Ser. Inhibition studies with alcohol dehydrogenase inhibitors pyrazole, 4-methylpyrazole, and cibacron blue 3GA were also performed. Activity measurements on crude extracts of larvae and flies from isogenic lines of ADH-FCh.D. revealed a consistently higher activity than in ADH-71k-containing strains, in contrast to the original strains.K.Th.E is indebted to the Royal Norwegian Council for Technological and Scientific Research for their postdoctoral fellowship. Prof. J. S. McKinley-McKee gave me the opportunity to work in his laboratory. I thank Dr. Knut Sletten of the Biochemical Institute for the kind gift of 2-methoxyethanol and amino acid analysis of some samples. The Biological Institute, Oslo, Section of General Genetics, is gratefully acknowledged for enabling me to use their fly-breeding facilities. Dr. John B. Gibson provided us with a sample of FCh.D. flies for the construction of isogenic lines in which Dr. Johan Hageman participated, owing to Postdoctoral Grant 436-931-P from the Foundation of Biological Research (BION), which is subsidized by the Netherlands Organization for Scientific Research (NWO). J. H. and Paula Truyens were involved in the measurements on the crude extracts. Work at Victoria University was supported by the VUW Internal Grant Committee.     

Specific binding of anti-myosin and -actin γ-globulins to the surface of trypsin-dissociated embryonic chick cells

Summary ¹²⁵I-labelled sheep anti-rabbit -globulin antibodies were used to locate rabbit antibodies to smooth- and striated-muscle actomyosins at the surface of trypsin-dissociated embryonic chick cells. Statistical analysis of electron microscope autoradiographs revealed that the plasma membrane of these cells was significantly labelled with both antibodies. Further tests revealed that there were a significantly greater number of antigenic sites present on the cell surface for the gizzard smooth-muscle antibodies than for those against pectoralis striated-muscle actomyosin.It was further shown that both the rate and extent of binding of the ¹²⁵Ilabelled smooth-muscle actomyosin antibodies to the cells were greater than for anti-striated-muscle -globulins. Binding of the former was reduced to a level similar to that of ¹²⁵I-NIS conjugate by preincubation of the y-globulins with smooth-muscle heavy meromyosin, while a similar reduction was observed when anti-pectoralis actomyosin was treated with actin.It was concluded that actin- and myosin-like proteins must now be considered as integral components of the plasma membrane.The authors wish to thank Dr. W. Sinclair (Zoology) and Miss S. Lutkins (Statistics Department) for assistance with the statistical analysis and are grateful to Professor N. A. Mitchison (Zoology Department, University College London) for providing a control sample of ¹²⁵I-labelled sheep anti-rabbit -globulin, Dr. D. Catty (Experimental Pathology Department, Birmingham University) for donating sheep anti-rabbit serum and Dr. U. Gröschel-Stewart (Zoologisches Institut der TH., Darmstadt, Federal Republic of Germany) for the rabbit anti-actomyosin antibodies. Miss B. Morris and Messrs. P. C. Lloyd, D. Williams and J. Meredith gave skilled technical assistanceThis investigation was supported by grants from Science Research Council, Cancer Research Campaign and Deutsche Forschungsgemeinschaft.     

Single Sensillum responses in the male mothAdoxophyes orana (F.v.R.) to female sex pheromone components and their geometrical isomers

Summary A technique is described for the recording of receptor and action potentials from the outer dendritic segments of the olfactory cells in individual antennalSensilla trichodea in insects. The 50 m long olfactory hairs on the antennae of adult male summerfruit toftrix moth,Adoxophyes orana, are shown to possess two cells responsive to the female sex pheromone (a 91 mixture ofcis-9 andcis-11-TDA (= tetradecen-1-ol acetate)). One of these cells (typeB) is sensitive tocis-9-TDA, the other (type A) mainly responds tocis-11-TDA and, to a much smaller extent, tocis-9-TDA. The behavioural inhibitorstrans-9 andtrans-11-TDA evoke small responses in both cells, which may have been caused by contamination of these substances by thecis isomers (Fig. 6).It appears that the pheromone receptor cells are not tuned to the optimal 91 mixture (Fig. 7). Hence, the attractiveness of the pheromone should be determined in the central nervous system by comparison of the responses from theA andB cells.A rough calculation indicates that the males are very well able to discriminate between different mixture ratios. It is suggested that thecis-9-/cis-11-TDA ratio excreted by the females shows a considerable variation.I am much indebted to Prof. Dr. D. Schneider for the use of facilities in his laboratory at the Max-Planck-Institut für Verhaltensphysiologie, Seewiesen (Federal Republic of Germany), and to all colleagues at this laboratory, especially Dr. K.-E. Kaissling, for their help. I am also grateful to Dr. F.W. Maes, Department of Zoology, State University of Groningen (Netherlands), for many discussions and his very valuable suggestions and help. I thank Drs. A.K. Minks and S. Voerman, Laboratory for Research on Insecticides, Wageningen (Netherlands), for the supply of the maleA. orana pupae and the chemicals; Mrs. C. Huss-Hahn, Mrs. G.W. De Vries-Nijboer and Miss M.J. Den Otter for technical assistance; Mr. D. Visser for preparing the figures; and Dr. G. Thomas for correcting the English text and constructive criticism. The investigations were supported by the Alexander von Humboldt-Stiftung and the Netherlands Organization for the Advancement of Pure Research (ZWO).     

Occurrence of Falcarinol and Falcarindiol In Tomato Plants after Infection with Verticillium albo-atrum and Characterization of Four Phytoalexins by Capillary Gas Chromatography-Mass Spectrometry

Falcarinol and falcarindiol were isolated from tomato vascular tissue infected with Verticillium albo-atrum and identified. Separation and characterization of trimethylsilyl derivatives of four tomato phytoalexins could be obtained by capillary gas chromatographymass spectrometry. We are most grateful to Dr. P. J. G. M. de Wit , Agricultural University, Wageningen, to Dr. D. T. Coxon , Food Research Institute, Norwich and to Dr. M. S. Kemp , Long Ashton Research Station, Bristol for making their analytical data available for us. Also thanks are due to Miss J. I. Liem , Mr. G. Verweij and C. Loriaux for their assistance.     

A point mutation in the N-terminus of ribulose-1,5-bisphosphate carboxylase affects ribulose-1,5-bisphosphate binding

Mutagenesis in vitro of the gene encoding the large subunit of ribulose-1,5-bisphosphate carboxylase/ oxygenase (EC 4.1.1.39) from Anacystis nidulans was used to generate novel enzymes. Two conserved residues, threonine 4 and lysine 11 in the N-terminus were changed. The substitution of threonine 4 with serine or valine had little effect on the kinetic parameters. The substitution of lysine 11 with leucine, which is non-polar, increased the K _m for ribulose-1,5-bisphosphate from 82 to 190 M but its replacement with glutamine, which has polar properties, had no appreciable effect.Abbreviations Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP ribulose-1,5-bisphosphate - LSU large sub-unit of Rubisco - SSU small subunit of Rubisco We thank Dr. S. Gutteridge (DuPont, Wilmington, USA) for structural information and for his comments on the results described. The technical assistance of Mr. A. Cowland and Mr. I. Major was invaluable.     

Rational men and the explanatory model approach

The previous issue of Culture, Medicine and Psychiatry (Vol. 5, N. 4) included my article When Rational Men Fall Sick: An Inquiry into Some Assumptions Made by Medical Anthropologists together with a series of comments. This paper consists of my replies to some of the commentators and a case study illustrating my points.My collaborators in this research were two physicians, Dr. Robert Like, of the Department of Family Practice of Case Western Reserve University and Dr. Rivka Plotkin of the Ben-Gurion University of the Negev (Israel). Also, I want to thank Avraham Blidstein for his invaluable assistance.     

Improvements in immunostaining samples embedded in methacrylate: localization of microtubules and other antigens throughout developing organs in plants of diverse taxa

Microtubules are important in plant growth and development. Localizing microtubules in sectioned material is advantageous because it allows any tissue of interest to be studied and it permits the positional relations of the cells within the organ to be known. We describe here a method that uses semi-thin (0.5–2 m) sections of material embedded in butyl-methylmethacrylate, to which 10 mM dithiothreitol was added. After removing the embedding material and using indirect immunofluorescence staining, we obtain clear images of microtubules, actin microfilaments, callose and pulse-fed bromodeoxyuridine. This method works on the root tissues of Arabidopsis thaliana(L.) Heynh, Pinus radiataD. Don, Zamia furfuraceaAit., Azolla pinnataR. Br. and on sporophytic tissues of Funaria hygrometricaHedw. In general, most of the cells in the organs studied are successfully stained. Using this method, we find that interphase meristematic cells in all of these species have microtubules not only in the usual cortical array but also throughout their cytoplasm. The presence of the calcium chelator ethylene glycol-bis(-aminoethyl ether)N,N,N,N-tetraacetic acid EGTA in fixation buffers led to some tissue damage, and did not enhance the preservation of microtubules. The common assumption that EGTA-containing buffers stabilize plant microtubules during fixation appears unwarranted.Abbreviations BrdU 5-bromodeoxyuridine - DTT dithiothreitol - EGTA ethylene glycol-bis(-aminoethyl ether) - N,N,N,N tetraacetic acid We thank Ann Cork for technical assistance, Professor B.E.S. Gunning (Australian National University) and Drs. A.R. Hardham (A.N.U.) and R.E. Williamson (A.N.U.) for intellectual and material support, Dr D. McCurdy (A.N.U.) for the purified anti-actin antibody, and Professor B. Stone (La Trobe University, Melbourne, Australia) for generously providing the anti-callose antibody. We also thank the Electron Microscopy Unit of A.N.U. for the use of facilities. L.C.F. gratefully acknowledges financial support from the National Sciences and Engineering Research Council of Canada.     

Some effects of electrical stimulation and exogenous metabolites on the contractile activity and the ultrastructure of the radula-muscle of Buccinum undatum

Summary The effect of various metabolites on the contractile pattern of the radulamuscle of Buccinum undatum was recorded. Its ultrastructure was studied after varying periods of spontaneous and electrically induced work.The effect of added substrates on the contractile behaviour of the radula-muscle was most pronounced after 12 hours of work or more. Addition of succinate caused a relaxation of the muscle, and its contractions were inhibited. Addition of glutamate had the opposite effect and caused a marked contraction of the muscle. The contractile pattern was not influenced by -ketoglutarate. These results indicate that factors other than energy supply influenced the response of the radula-muscle.The ultrastructure of the control muscles and of the electrically stimulated muscles showed some changes referable to the isolation of the muscle. Contrary to the controls, those muscles that had been stimulated for 4 and 12 hours respectively showed a more regular organisation. The filaments were more parallel and electron dense dots occurred arranged in transverse or oblique bands. The distance between the bands was around 1 . This organisation of the radula-muscle was discussed and compared with that of banded muscles of various kinds. Attention was drawn to the similarities in appearance between the bands of the radula-muscle and of Z bands of developing striated vertebrate muscles. The mitochondria showed changes partly referred to the isolation of the muscle and partly to the experimental conditions.Our sincere thanks are due to Professor I. Agrell, Head of the Zoophysiological Institute, Lund, for his advice and support during the work.Thanks are also due to Dr. B. Swedmark and his staff of the Zoological Station, Kristineberg for kind help with animal material and to Professor C. G. Ahlström, Pathological Institute, Lund, for electron microscopic facilities. We thank Mrs. M. Carleson and Mrs. I. Hedström for most valuable technical assistance during the electron microscopic work. The work was supported by grants from Swedish Natural Science Research Council and the Royal Physiographic Society of Lund.     

The effect of a seed source on primary succession in a forest ecosystem

An analysis of the Relative Importance Value Index (RIVI) of later successional tree species and the Shannon diversity indexH of all tree and shrub species was undertaken on previously mined sites within a sparsely forested area in central Florida, USA. A comparative analysis of the distance to a seed source and the age of a site suggested that the distance to a seed source was the best predictor (R ²=0.85) of the regeneration of the later successional species and a good predictor of species diversity. Both theRIVI of the later successional species and the diversity index decreased with the distance from the seed source. The lack of a seed source containing climax species resulted in arrested succession at some sites. It is suggested that biological information is the causative means of succession and the dispersal of this information entails spatial dependency while its introduction and development are time dependent processes.Research was part of a project of the Center for Wetlands, University of Florida, Gainesville under contract with the Florida Institute of Phosphate Research. Interactions of Wetlands with Phosphate Mining, H. T. Odum and G. R. Best, principal investigators. B. T. Rushton, J. Butner, G. R. Best, R. S. Schnoes and S. R. Humphrey are thanked for the use of their data.     

Measurement of the electrical resistance of plasmodesmata and membranes of corn suspension-culture cells

Electrophysiological investigations of intercellular communication and membrane resistance in higher plants have been hampered by the difficulty in measuring these quantities independently. Uncertainty about the position of an electrode inserted into vacuolate tissue has further complicated such measurement. To overcome these problems sister cell pairs of a Zea mays L. Black Mexican Sweet suspension culture were used and dye was injected from the current-injecting electrode to determine the location of the electrode tip in each experiment. Of the impalements, 72% were cytoplasmic. The presence of plasmodesmata was fully incorporated into the electriccircuit model for the cell, and the resistance of the membrane of the current-injected cell was calculated, separate from the plasmodesmata resistance. This avoided some of the confusion resulting from work on multicellular tissue in which the position of the electrode and the extent of intercellular coupling is not determined. Using this technique, plasma-membrane resistivity was measured as 0.65 ·m², the resistivity of the tonoplast and plasma membrane in series was 1.35 ·m², and the resistance of a single plasmodesma was calculated to be 53 ± 11 G.Abbreviations BMS Black Mexican Sweet - PD potential difference - R_j resistance of the plasmodesmata in the junction between cells - R_m resistance of the plasma membrane of the current-injected cell - R_t resistance of the tonoplast - V₁, V₂ membrane PDs of sister cells This work was funded by an Australian Research Council grant to R.L.O. We are grateful to Dr. Maret Vesk (Electron Microscope Unit, The University of Sydney) for assistance with the preparation of EM sections, and to Dr. Richard Brettell (C.S.I.R.O. Division of Plant Industry) for assistance with the BMS culture.     

The appearance of a type of cortical vesicles subsequent to fertilization of the sea urchin egg,their character and possible function

Summary Three different types of vesicles present before fertilization in the sea urchin egg were examined. The a-type corresponds to rough endoplasmic vesicles; the vesicles of b-type are rather smooth but may have vestigial granules within their membranes; the c-type belongs to the multivesicular bodies. Upon fertilization, vesicles appear in the outer cortical zone (vesicles of d-type). The majority of them arises by budding from the vesicles ofb-type. The budding occurs mainly at the basis of or within ridges of the cell surface; they may also be present in broader microvilli. The distance between the ridges was varied by early transfer of the eggs to calcium-free sea water. An inducing effect of the ridges on location of theb-vesicles and on the formation ofd-vesicles by budding could thus be demonstrated.Thed-vesicles appearing upon fertilization resemble in size and structure Golgi vesicles formed by budding from Golgi bodies present in the interior cortex or below it. Also theb-vesicles have their counterpart in the Golgi bodies. Theb andd-vesicles are therefore regarded as a Golgi system in which theb-vesicles represent dispersed Golgi bodies and thed- vesicles Golgi vesicles. Thed-vesicles may be designated as cortical Golgi vesicles, (c.G.v.).In thec-vesicles i.e. the multivesicular bodies (m.v.b.), a nucleid was observed which may be subdivided. A compartmentation of m.v.b. was observed which may lead to a detachment of vesicles of about the same size as thed-vesicles (c.G.v.) but probably of a different character.The differentiation of the fertilization membrane of the sea urchin egg occurs in two stages: the assembly and the solidification stage. The tentative conclusion is drawn that a secretion from the c.G.v. functions as an agent in the solidification process. The c.G.v. may also act upon the hyaline layer, both in its early formation and its maintenance during the course of embryonic development.The material for the present investigation was collected at Kristineberg Zoological Station and at Stazione Zoologica, Naples. The writer is indebted to the authorities of these stations for generous helop. Financial support was received from the Swedish Natural Sciences Research Council and the Swedish Cancer Society for which I express my gratitude.I also express my gratitude to Dr.Björn Afzelius for surveying the electron microscopic part of the work, to Dr.Jane Baxandall for permission to study her original electron micrographs and to Dr.Elsa Wicklund and Dr. L.Contoli for contribution to the experiments on the effect of calcium-free sea water. I thank Mrs.Astri Runnwström and Mrs.AnneMarie Ede for their able assistance.This research was carried out in association with the Research group of embryology for the study of cellular differentiation of the Department of Zoology, University of Rome (Director Professor P.Pasquini).     

Atomic force microscopy of peritoneal macrophages after particle phagocytosis

The atomic force microscope was used to image peritoneal macrophages after phagocytosis of latex beads with 0.45 m in diameter and of zymosan particles. The rigidity of the phagocytosed material allowed to image the live membrane at forces below 2 nn. Repeated scanning of the membrane unavoidably caused the protrusion of the beads and increased their virtual height. The influence of fixation by glutaraldehyde on the image and the corresponding force vs. distance curves were analyzed and compared. Short treatment with Triton X-100 enabled us to identify intracellular components, such as embedded latex beads, cell nucleus and cytoskeletal strands. The data demonstrate that it is possible to image living cells if they are bolstered by stiff material.The authors wish to thank Dr. H. Oberleithner for his generous support, helpful discussions and the suggestion of Triton treatment. The authors gratefully acknowledge Dr. I. Jahns for establishing the AFM technique at the Institute of Physiology. The work was supported by the Deutsche Forschungsgemeinschaft Projekt No. La 315/4-1.     

Yards,corridors, and mosaics: How to burn a boreal forest

Ethnographic studies have established that, until shortly after World War II, Indians in northern Alberta regularly and systematically fired habitats to influence the local distribution and relative abundance of plant and animal resources. In ways similar to what has been reported for hunter-gatherers in other regions, this pyrotechnology contributed to an overall fire mosaic that, in this case, formerly characterized northern boreal forests. Crosscultural comparisons of these practices with those in other parts of North America, as well as in several parts of Australia, illustrate functionally parallel strategies in the ways that hunter- gatherers employed habitat fires, specifically in the maintenance of fire yards and fire corridors in widely separated and different kinds of biological zones.We would like to thank Ross Wein tor his comments and suggestions on this paper, especially his ideas about the characteristics of fire mosaics as they would occur under natural conditions in boreal forests. We are also indebted to several granting agencies for funds that supported our earlier research. They include the Social Sciences and Humanities Research Council, the Museum of Man, Fire Science Center (University of New Brunswick), the Boreal Institute for Northern Studies (University of Alberta), the Australian Institute for Aboriginal Studies, and the Northern Australian Research Unit (Australian National University).     

Fertilization in maize indeterminate gametophyte1 mutant

Summary. Mature embryo sacs of the maize mutant indeterminate gametophyte1 displayed different cellular patterns compared to those of the wild type. About 40% of the ig1 embryo sacs contained three or more synergids and two or more egg cells at the micropylar end. During fertilization in embryo sacs with two synergids, both of them frequently degenerated and were penetrated by two pollen tubes. 75% of the embryo sacs containing three or more synergid cells were penetrated by two or more pollen tubes, although most of them had only one degenerated synergid. Multiple fusions between the sperm cells and eggs frequently occurred in the same embryo sac, which subsequently generated multiple embryos. There were two or more central cells in about 33% of ig1 embryo sacs. The largest central cell was usually adjacent to the egg apparatus and contained two unfused polar nuclei, while those extra central cells located at the chalazal end usually had a single nucleus. Fertilization occurred only between the male gamete and the largest binucleate central cell. The extra central cells eventually degenerated after fertilization.Present address: GI Basic Research Center, Mayo Clinic, Rochester, Minnesota, U.S.A.Correspondence and reprints: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Science, China Agricultural University, Beijing 100094, Peoples Republic of China.     

Production of specific-protein secretion granules by fat body cells of the blowfly,Calliphora erythrocephala

Summary During the first four days of the imaginai stage the fat cells of ovariectomized females of Calliphora develop a protein synthetic apparatus, and produce dense bodies (lysosomes) as do the fat cells of normal females, but apparently they cannot synthesize the protein secretion granules that characterize the productive phase of the fat cells of normal females and that we believe to represent vitellogenin. Injection of ovariectomized females with -ecdysone restored the ability of the fat cells to produce the secretion granules. It is suggested that the ovary gives off a factor which induces the production of the protein secretion granules by the fat cells, and that the factor from the ovary can be substituted by -ecdysone. This, we believe, is the first ultrastructural evidence for an effect of the ovary and of -ecdysone on the synthesis of specific protein.We are grateful to the Carlsberg Foundation and to the Danish Science Research Council for generous grants, and to the latter for placing an electron microscope at our disposal. It is a pleasure to thank Dr. Gareth Griffiths for valuable advice as to the preservation of the fat body tissue. We also thank Mrs. Lotte Bakhoj and Mrs. Elsebeth Lund for skilful technical assistance1896–1976     

Expression of glutamine-synthetase genes in cotyledons of germinating Phaseolus vulgaris L.

In the legume Phaseolus vulgaris L., glutamine synthetase (GS; EC.6.3.1.2.) is encoded by four actively transcribed genes, gln-, gln-, gln- and gln-. We have studied the expression of these genes in cotyledons during seed germination and have studied the effect of light and nitrate on this process. An RNase-protection method, used to detect the abundances of GS mRNAs, revealed that the four GS genes are differentially expressed in the germinating cotyledons. The gln-. mRNA was present in dry seeds and was the most abundant GS mRNA during early stages of germination. The gln- and gln- mRNAs were first detectable 2 d after sowing and their abundances differed in light- and dark-grown cotyledons at later stages of germination. The gln- mRNA (which encodes the plastid-located GS) was detectable only in light-grown cotyledons, at a low abundance. A nitrate supply of 2 mM had only a minor effect on the expression of the GS genes. Western immunodetection and ion-exchange high-performance liquid chromatography demonstrated that the polypeptide and isoenzyme were present in extracts of dry seeds and represented the major GS products at 2 d and 4 d. Both the and polypeptides appeared at the 2-d stage. The role of differential GS gene expression in controlling cotyledonary GS activity is discussed.Abbreviations 1D, 2D one-, two-dimensional - GS glutamine synthetase - GS_t GS transferase activity - IEX-HPLC ion-exchange high-performance liquid chromatography - kDa kilodaltons - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis We are grateful to the Association of Commonwealth Universities and the Science and Engineering Research Council for financially supporting R.S. and to the S.E.R.C. for a grant to support M.J.B. We would like to thank Dr K.J.F. Farnden (University of Otago, New Zealand) and Dr T.H.N. Ellis (John Innes Institute, Norwich) for scanning the autoradiographs for Fig. 2.     

In vivo estrogen uptake by individual cell types of the rat anterior pituitary after short-term castration-adrenalectomy

Summary In vivo estrogen uptake was measured in five anterior pituitary cell types of the rat by a quantitative autoradiographic-immunocytochemical technique. In male and female rats that had been castrated and adrenalectomized for one day all five cell types showed nuclear concentration of label one hour after injection of ³H-estradiol. The order of labeling intensity was lactotropes > somatotropes > gonadotropes > corticotropes > thyrotropes. No significant overall sex difference in estrogen uptake was apparent although male pituitaries tended to take up slightly more. Physiological correlates to these data are discussed.Supported by PHS grant HD 12173 and Research Career Development Award HD 00243I wish to acknowledge Mr. Sing Kung Lau for his excellent technical assistance and Dr. P. Rodier for her advise and assistance with the statistical analysis. I also wish to thank Dr. A.F. Parlow and NIAMDD for antisera against rLH, hFSH, rPRL and rTSH and Dr. P. Petrusz, University of North Carolina, for antisera against bGH and h endorphin