Environmental effects on circadian rhythms in photosynthesis and stomatal opening

Persistent circadian rhythms in photosynthesis and stomatal opening occurred in bean (Phaseolus vulgaris L.) plants transferred from a natural photoperiod to a variety of constant conditions. Photosynthesis, measured as carbon assimilation, and stomatal opening, as conductance to water vapor, oscillated with a freerunning period close to 24 h under constant moderate light, as well as under light-limiting and CO₂-limiting conditions. The rhythms damped under constant conditions conducive to high photosynthetic rates, as did rates of carbon assimilation and stomatal conductance, and this damping correlated with the accumulation of carbohydrate. No rhythm in respiration occurred in plants transferred to constant darkness, and the rhythm in stomatal opening damped rapidly in constant darkness. Damping of rhythms also occurred in leaflets exposed to constant light and CO₂-free air, demonstrating that active photosynthesis and not simply light was necessary for sustained expression of these rhythms. This is CIWDPB Publication No. 1142 This research was supported by National Science Foundation grant BSR 8717422 (C.B.F.) and a U.S. Department of Agriculture training grant to Stanford University (T.L.H.).     

Chloroplast development in isolated roots of Convolvulus arvensis (L.)

Summary The fine structure of chloroplast development is described for isolated roots of Convolvulus arvensis. Stages in the transition from the leucoplast, characteristic of dark-grown roots, to the chloroplast, found in light-grown roots, are defined and related to chlorophyll content of the root tissue. The interdependence of tissue type and organellogenesis has been investigated for three tissues in the primary root: cortical parenchyma, pericycle and stelar parenchyma tissue. Plastids in cells of all three tissues follow the same sequence of chloroplast development, although the rate of development is dependent on the tissue type.This work was supported by National Science Foundation grant GB-5040 and U.S. Public Health Service grant No. GM-16353.     

Genetic mapping of aminoglycoside and fusidic acid resistant mutations in Bacillus subtilis

Summary Mutations governing resistance to neamine, neomycin, kanamycin and fusidic acid have been mapped within the ribosomal region of theBacillus subtilis genome using PBS1-mediated transduction. The probable order of these closely linked markers is: This work was supported by a predoctoral training grant, GM-1290, from the National Institutes of Health, administered by the Department of Microbiology, N.Y.U. School of Medicine, and by a research grant from the National Science Foundation, GB-16782, awarded to I.S.     

Cytodifferentiation in theRana pipiens oocyte

Summary This communication is concerned with an analysis of details in the morphogenesis of intramitochondrial yolk in oocytes of immatureRana pipiens, at different times during the prolonged diplotene stage of meiotic prophase in adult females, in fully-grown oocytes, and in those eggs artifically activated during early cleavage. The fine structure of the germinal cytoplasm of cleaving eggs is also characterized. The observations reported are discussed in relation to results obtained by others and in terms of current views regarding mitochondrial function. This investigation was supported by a research grant from the National Science Foundation.     

Ultrastructural changes in nurse and follicle cells during late stages of oogenesis in Drosophila melanogaster

Summary During stages 11 and 12, follicle cells surrounding the nurse cells produce lysosomes which presumably aid in the breakdown of the nurse cells. Accompanying a DNA reduction in nurse cell nuclei are several characteristic morphological changes including the appearance of intranuclear rod-like structures and nuclear granules about 300 Å in diameter. Similarities between structures seen in Drosophila nurse cell nuclei and those seen in other organisms are discussed.This research was supported by U. S. Public Health Service Grants 5TIGM903-3 and 1-F1-GM-33, 385-01 and National Science Foundation grant GB-7457.     

Primitive-like metaphloem sieve elements in the aerial stem ofEquisetum hyemale

Summary Internodal metaphloem sieve elements located near the nodes of aerial stems ofEquisetum hyemale contain very oblique end walls. During maturation, the connections, or plasmodesmata, in these walls undergo little or no structural modification. By contrast, the endwall connections uniting the protoplasts of mature sieve elements elsewhere in the aerial stem ofE. hyemale are pores.This work as supported by U.S. National Science Foundation grant GB 31417 to R. F.Evert.     

Dynamical synaptic plasticity: a model and connection to some experiments

 Using a modified version of a phenomenological model for the dynamics of synaptic plasticity, we examine some recent experiments of Wu et al. [(2001) J Physiol 533:745–755]. We show that the model is quantitatively consistent with their experimental protocols producing long-term potentiation (LTP) and long-term depression (LTD) in slice preparations of rat hippocampus. We also predict the outcome of similar experiments using different frequencies and depolarization levels than reported in their results. Received: 3 September 2002 / Accepted in revised form: 22 October 2002 / Published online: 24 February 2003 Correspondence to: H.D.I. Abarbanel (e-mail: hdia@jacobi.ucsd.edu) Acknowledgements. We are very grateful to A. Selverston and D. Feldman for conversations about this work. This work was partially supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Engineering and Geosciences, under grants No. DE-FG03-90ER14138 and No. DE-FG03-96ER14592, by a grant from the National Science Foundation, NSF PHY0097134, by a grant from the Army Research Office, DAAD19-01-1-0026, by a grant from the Office of Naval Research, N00014-00-1-0181, and by a grant from the National Institutes of Health, NIH R01 NS40110-01A2. This work was also partially supported by M. Ciencia y Tecnologa BFI2000-0157 (R.H.).     

Fine structure of the tip of the labellar taste hair of the blow flies,Phormia regina (Mg.) and Calliphora vicina R.-D. (Diptera,Calliphoridae)

Summary The labellar taste hairs of the blow flies, Phormia regina and Calliphora vicina, have an opening mechanism at the tip which consists of two stump cuticular prongs and a funnel-like cuticular pouch. Opening and folding of these structures are regulated by the pressure within the dendrite-free lumen of the hair. The extrusion of viscous substance at the tip of the taste hair is possible through spongy cuticle and one pore in each prong; it seems likewise to depend on the pressure within the dendrite-free lumen and results in regional collapsing of this lumen. Described and discussed are: The cuticle and pores of the structures at the hair tip, pore filaments which extend from the dendrites, and the number and arrangement of the dendrites.This work was supported by a grant from the 7USDA, Entomology Research Division, Beltsville, Md., and the grant GB-13500 from the National Science Foundation.We thank Dr. J. F. Worley, USDA, Plant Science Research Division, Beltsville, Md., for his collaboration in fluorescence microscopy.     

Modeling insect dispersal and estimating parameters when mark-release techniques may cause initial disturbances

We consider the problem of quantitatively modeling movements of marked flea beetles in cultivated arrays of the cole crop, collards (Brassica oleraceae). Methods for the estimation of temporally and spatially dependent parameters in general dispersal models are outlined and a summary of our findings using these methods with flea beetle data is given.This research was supported in part by the National Science Foundation under NSF # MCS-8205335 and by the U.S. Air Force Office of Scientific Research under contract AFOSR 81-0198. Part of the research was carried out while this author was a Visiting Professor in the Department of Mathematics at Southern Methodist UniversityThis research was supported in part by the National Science Foundation under NSF # DEB-8207117This research was supported in part by the National Science Foundation under NSF # MCS-8200883. Part of the research was carried out while the first and third authors were visitors at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, Virginia which is operated under NASA contracts NAS1-15810 and NAS1-16394     

Electron microscope observations on the salivary gland of the cockroach,Periplaneta americana

Summary The salivary gland of the cockroach was studied with the electron microscope. Structural modifications of the cells comprising the duct system as well as the fine structure of the cells comprising the secretory tissue have been characterized. An attempt is made to correlate certain of the structural features with functional significance.This investigation was supported by grants (RG-9230, 4706, 5479) from the National Institutes of Health and a grant (G-9879) from the National Science Foundation.     

Structure and development of the sieve-cell protoplast in leaf veins ofWelwitschia

Summary Tissue of one-year-old leaves ofWelwitschia mirabilis was fixed in glutaraldehyde and postfixed in osmium tetroxide for electron microscopy. Mature sieve cells contain nuclei composed of peripherally-distributed chromatin material and an intact envelope with pores. During sieve-cell development many mitochondria become closely associated spatially with the nucleus. In addition to a nucleus and mitochondria, the mature, plasmalemma-lined sieve cell contains plastids and abundant smooth endoplasmic reticulum, which generally occurs in massive aggregates at the sieve areas. Dictyosomes and ribosomes are lacking and a tonoplast is not discernible in mature sieve cells. P-protein is not present at any stage of development.This work was supported in part by a grant from the South African Council for Scientific and Industrial Research and in part by the U.S. National Science Foundation (GB 31417).     

Defined nutrient medium for the in vitro maintenance ofXenopus laevis oocytes

Summary A procedure is described for the isolation and culture of large numbers of follicle cell-freeXenopus laevis oocytes in all stages of development. The isolation procedure involves the incubation of pieces of ovary in a calcium-free solution OR2 containing 0.2% collagenase. A defined nutrient medium for the maintenance of the oocytes in vitro is presented. It is shown that this medium, referred to as DNOM, can maintain certain morphological and functional characteristics of oocytes for periods up to 3 weeks. Research supported by grant BMS 74-18790 from the National Science Foundation to JJE. Operated by Union Carbide Corporation for the U.S.E.R.D.A.     

The stem and leaf lectin of Dolichos biflorus L., previously thought to be cell wall associated,is sequestered in vacuoles

Post-embedding immunogold labeling has shown that the DB58 lectin is sequestered in vacuoles. Previous evidence indicating that a significant fraction of the DB58 lectin is cell wall associated is shown to be in error.Abbreviations PBS 10 mM sodium phosphate, pH 7.1, 154 mM sodium chloride - TBS 20 mM Tris base, pH 7.6, 137 mM sodium chloride We thank Dr. Mary Alice Webb for sharing her electron-microscopy expertise. This work was supported by National Science Foundation grant DCB-9004967 (M.E.E.) and a University of California, Davis, Jastro-Shields fellowship (T.W.B.).     

Related base sequences in the DNA of simple and complex organisms. III. Variability in the base sequence of the reduplicated genes for ribosomal RNA in the rabbit

A comparative study has been made of the arrangement of base sequences in the ribosomal RNA cistrons of Escherichia coliand rabbit DNA. This was accomplished by examination of the thermal stability profiles of DNA/RNA hybrids formed by the two types of ribosomal RNA under various conditions. The thermal stabilities of ribosomal RNA hybrids of rabbit origin are more dependent on the conditions of reaction during the formation and are always lower than those of E. coli RNA. It is concluded that the rabbit ribosomal RNA hybrids are formed mainly from mismatching between RNA molecules and DNA sites other than those from which they were transcribed. Thus, the cluster of ribosomal RNA cistrons in a mammalian DNA, representing a historical series of tandem duplications, exhibits intercistronic base sequence divergence. This research was supported by a research grant from the National Science Foundation (GB 6099) and a predoctoral traineeship (to R.L.M.) from the U.S. Public Health Service.     

Light and electron microscopic detection of (3 Gal β1,4 GlcNAc β1) sequences in asparagine-linked oligosaccharides with the Datura stramonium lectin

Summary The Datura stramonium lectin recognizes with high affinity the disaccharide N-acetyllactosamine (Gal 1,4 GlcNAc). We have developed a highly specific cytochemical affinity technique in which an ovomucoid-gold complex serves as second step reagent for the visualization of this lectin bound to reactive sequences present in tissue sections. The lectin binding sites were detected in semithin and ultrathin sections of aldehyde-fixed and low temperature Lowicryl K4M embedded tissues. For light microscopical labeling the photochemical silver reaction for signal amplification was required. The application of this technique for the detection of N-acetyllactosamine containing asparagine-linked oligosaccharides in various intracellular organelles and the plasma membrane is demonstrated.This study was supported by the Swiss National Science Foundation grant nr. 31-26273.89 (to J.R.) and GM 29470 from the National Institutes of Health (to I.J.G.). Dr. G. Egea was a recipient of a European Molecular Biology Organization long term fellowship.     

The juvenile phase inBryophyllum daigremontianum

Summary Young plants ofBryophyllum daigremontianum, which do not form flowers in response to the change from long day to short day, can easily be induced to flower by grafting onto flowering donor stocks, indicating that the growing points of young plants are fully capable of responding to the floral stimulus but their leaves are incapable of producing the latter.With 3 Figures in the TextThis work was in part supported by the National Science Foundation, grant G-17483.     

Lymphatic endothelium in health and disease

The lymphatic vascular system has an important role in the maintenance of tissue fluid pressure homeostasis, in the mediation of the afferent immune response via recruitment of antigen-presenting cells toward draining lymph nodes, and in the intestinal absorption of dietary lipids. Substantial progress in our understanding of the development and the molecular mechanisms controlling the lymphatic system has been made during the last few years, based on a recent wave of discoveries of lymphatic endothelial cell-specific markers and growth factors. This has also led to new insights into the role of lymphatic endothelium in a number of diseases, including primary and secondary lymphedemas. The emerging role of lymphatic endothelium in the context of inflammation indicates that therapeutics targeting the lymphatic vasculature might represent a new strategy for anti-inflammatory therapies. Research from the authors' laboratory is supported by National Institutes of Health grant CA69184, Swiss National Fund grant 3100A0-108207, Austrian Science Foundation grant S9408-B11, Cancer League Zurich, and Commission of the European Communities grant LSHC-CT-2005-518178 (M.D.).     

Immunohistochemical evidence for the presence of tryptophan hydroxylase in the brains of insects as revealed by sheep anti-tryptophan hydroxylase polyclonal antibody

Immediately following the discovery of tryptophan hydroxylase in Drosophila, we demonstrated the presence of tryptophan hydroxylase in the brain of the beetle Harmonia axyridis (Coleoptera: Coccinellidae). However, whether tryptophan hydroxylase is present in the brains of other insects is still a matter of discussion. In the current study, sheep anti-tryptophan hydroxylase polyclonal antibody has been applied to test for tryptophan hydroxylase immunoreactivity in a broader taxonomic range of insect brains, including holometabolous and hemimetabolous insects: one species each of Coleoptera, Hymenoptera, Diptera, and Blattaria, and two species of Lepidoptera. All species show consistent tryptophan hydroxylase immunoreactivity with distribution patterns matching that of serotonin. The immuno-positive results of such an antibody in brains from diverse orders of insects suggest that specific tryptophan hydroxylase responsible for central serotonin synthesis is probably present in the brains of all insects. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This work was supported by grants from the National Natural Science Foundation of China (grant no. 30470546) and the Natural Science Foundation of Jilin Province (grant no. 20030550–7).     

Auxin stimulates both deposition and breakdown of material in the pea outer epidermal cell wall,as measured interferometrically

The effect of auxin on the mass per area in the outer epidermal walls of third internodes of Pisum sativum L. cv. Alaska grown in dim red light was investigated using interference microscopy, and rates of net deposition of wall material were calculated. Examination of these net rates under different growth conditions showed that there is no simple relationship between the deposition of mass and growth. Net deposition can be proportional to growth when sufficient substrate for wall synthesis is available, as in intact plants, and in segments treated with indole-3-acetic acid (IAA) plus glucose. Net deposition can cause thickening of the walls when growth is small, as in the case of segments kept without IAA in the presence or absence of glucose, or segments whose growth is inhibited with mannitol. When substrate is limited and growth is large, however, wall expansion can occur with no net deposition, or an actual net loss of wall material can even take place. Auxin appears to induce a breakdown in the walls of segments treated in the absence of glucose, although it promotes synthesis when glucose is present. It is likely that IAA always induces a breakdown of wall material, but that the breakdown is masked when substrate is available for synthesis. Our results indicate that pea epidermal cells have two different auxin-stimulated mechanisms, wall synthesis and wall breakdown, potentially available to loosen their outer epidermal walls to bring about cell enlargement, alternatives which could be employed to different extents depending on substrate conditions.Abbreviation IAA indole-3-acetic acid M.S. Bret-Harte would like to thank Drs. Peter M. Ray, Stanford University, Winslow R. Briggs, Carnegie Institute of Washington, Stanford, Calif. USA, and Wendy K. Silk, of the University of California Davis USA, for helpful discussions, Dr. Briggs and the Carnegie Institute of Washington for the use of experimental facilities, and Dr. Ray for editorial assistance. This work was supported by a National Science Foundation Graduate Fellowship to M.S.B.-H., a National Science Foundation Postdoctoral Fellowship to T.I.B., and National Science Foundation grant DCB8801493 to P.B.G.