Further cytogenetic analyses of the Croatian triploid shallot “Ljutika” (Allium cepa var.viviparum, Alliaceae) and its comparison with the Indian triploid “Pran”

Feulgen and silver-stained karyotypes and meiosis of two triploid viviparous onion forms (Allium cepa var.viviparum), the Croatian Ljutika and the Indian Pran, were comparatively analyzed. The results of chromosome measurements show that Ljutika and Pran are karyologically not identical, although significant similarities were found in the morphology of their chromosomes. Five geographically distant clones of Ljutika showed good agreement in the number and gross morphology of the chromosomes and in the number and position of NORs and interphase nucleoli. Heterotrivalents were predominant in meiosis of Ljutika but a relatively high frequency of higher multivalents together with univalents and bivalents were also observed. The relationship between Ljutika and Pran and their possible origin are discussed.     

Tetracyclines modulate cytosolic Ca2+ responses in the osteoclast associated with “Ca2+ receptor” activation

We report the effects of tetracycline analogues on cytosolic Ca²⁺ transients resulting from application of ionic nickel (Ni²⁺), a potent surrogate agonist of the osteoclast Ca²⁺ receptor. Preincubation with minocycline (1 mg/l) or a chemically modified tetracycline, 4-dedimethyl-aminotetracycline (CMT-1) (1 or 10 mg/l), resulted in a significant attenuation of the magnitude of the cytosolic [Ca²⁺] response to an application of 5 mM-[Ni²⁺]. Preincubation with doxycycline (1 or 10 mg/l) failed to produce similar results. In addition, application of minocycline alone (0.1–100 mg/l) resulted in a 3.5-fold elevation of cytosolic [Ca²⁺]. The results suggest a novel action of tetracyclines on the osteoclast Ca²⁺ receptor.     

Growth,acetylene reduction activity and localization of nitrogenase in relation to vesicle formation in Frankia strains Cc1.17 and Cp1.2

A comparative study was conducted on the effect of NH₄Cl on growth, vesicle formation and formation of nitrogenase of Frankia strains Cc1.17 and Cp1.2, derived from root nodules of Colletia cruciata and Comptonia peregrina, respectively. On a medium without combined nitrogen (P-N), both strains formed spherical cells, called vesicles, like many other Frankia strains. Data are presented on the number of vesicles per mg protein, after cultivation in media with sodium propionate as C-source without combined nitrogen (P-N) or with 0.2 g NH₄Cl/l (P+N). Strain Cp1.2 as may other Frankia strains, showed on P+N medium a very strong reduction of vesicle formation of 99% relative to the number of vesicles formed on P-N medium, after 11 days growth. However, in strain Cc11.17 this reduction was only 70%. The occurence of relatively large numbers of vesicles in P+N media has not yet been reported for other Frankia strains. No acetylene reduction activity was found in NH ₄ ⁺ -grown cells. The regulation of induction of nitrogenase in Frankia by NH₄Cl was tested by immuno-gelectrophoresis using antisera against nitrogenase of Rhizobium leguminosarum PRE. The component I of the enzyme showed crossreactivity while the component II had only a weak crossreaction. The experiments indicated that no nitrogenase was detectable in the NH ₄ ⁺ -grown cells. For the localization of nitrogenase, relative amounts of the enzyme were compared in whole cells and vesicle-enriched fractions. Western blots showed a significant enrichment of nitrogenase in the vesicle fractions, which indicated that most of the nitrogenase was localized in the vesicle.     

Observations on the fine structure of the cercaria of Notocotylus attenuatus and formation of the cyst wall of the metacercaria

Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.     

N6-(Δ2-Isopentenyl) adenine inhibits the alcohol dehydrogenase activity in cell-free extracts of Zymomonas mobilis

The plant growth substance N⁶-(²-isopentenyl) adenine (i⁶Ade) significantly inhibits the rates of ethanol oxidation and acetaldehyde reduction in vitro by cell-free extracts of Zymomonas mobilis and of an Escherichia coli recombinant strain, containing the Z. mobilis adhB gene. The two-substrate kinetics of ethanol oxidation (forward) is affected by increasing values of dissociation constants for coenzyme and coenzyme —enzyme complexes in the presence of i⁶Ade, whereas the reaction maximum velocity (V _m) remains unchanged and reflects the competitive type of inhibition. Changes of the kinetic constants of acetaldehyde reduction (back) are similar, except the increasing value of V _m and correspond to the CIS (competitive inhibition and stimulation) type of inhibition. The estimated values of inhibition constants of the forward and back reactions are 0.39 ± 0.05 mM and 0.19 ± 0.06 mM, respectively.     

Studies on aneuploids of Petunia

Summary The seven possible primary trisomics of Petunia (2 n= 14) located in the progenies of triploid, hypertriploid and hypotriploid plants were distinguished from one another and from diploid on the basis of cytological and morphological criteria. They were provisionally named as Oval, Semi, Slender, Pseudonormal, Arrow, Narrow and Giant. In three of the trisomics, the extra chromosome was identified for the first time at pachytene stage. Postpachytene studies revealed no precise relationship between the length of extra chromosome and the frequency of multiple association.     

Genetics of Ia-like alloantigens in chickens and linkage withB major histocompatibility complex

Two sets of backcross matings were performed to test for linkage between genes coding for the Ia-like antigens (Ia) and the B erythrocyte antigens (Ea-B) of the chicken. Evidence is presented which indicates that the la antigens are determined by a single codominant locus and that theEa-B and Ia loci are on the same chromosome. Failure to detect a single recombinant between theEa-B and Ia loci out of 208 progeny suggests close linkage of the two genes with a map distance of up to about 2 centimorgans. The Ia genes are thus included in theB major histocompatibility complex of the chicken.     

Polysaccharide and protein secretion by grass microhairs

Summary Secretory activities of bicellular microhairs from grasses belonging to the subfamilies Chloridoideae, Arundinoideae, Panicoideae, and Bambusoideae, and including the chloridoid, panicoid and Enneapogon microhair morphological types, have been investigated. Light microscopic histochemistry indicated that all microhairs studied secrete polysaccharide and protein (or glycoprotein), including those which also secrete salt. Localization of polysaccharide at ultrastructural level using periodic acid-thiocarbohydrazidesilver proteinate staining revealed that in panicoid type microhairs dictyosomes are involved in polysaccharide secretion, whereas in the chloridoid and Enneapogon types partitioning membranes seem to be involved instead.Abbreviations Ag silver precipitates representing localization of polysaccharide - BC basal cell - C cuticle - CC cap cell - CH cuticular chamber - CN system of membrane bound channels and vesicles - CP chloroplast - CW cell wall - D dictyosomes - M mitochondria - N nucleus - PTM partitioning membranes - RER rough endoplasmic reticulum - S secretory material - St starch grain - US unstained dictyosome cisternae - V vesicle     

Injury to potato leaves exposed to subzero temperatures in the absence of freezing

Electrolyte leakage was measured in hardened and nonhardened leaves of three potato species, Solanum tuberosum L., S. acaule Bitt. and S. commersonii Dun., and one interspecific cross, Alaska Frostless (S. acaule x S. tuberosum) when exposed to various subzero temperatures. The leaves were undercooled (no ice present) from 0°C to -12.5°C for 45 min and to-4°C for up to 10 d. Regardless of the degree of undercooling no injury was observed in any of the potatoes, hardened or nonhardened, for up to 12 h. After 5 d, however, electrolyte leakage was observed in hardened S. tuberosum, S. acaule and S. commersonii, and in nonhardened Alaska Frostless. After 10 d exposure all potatoes, hardened and nonhardened, showed a significant amount of electrolyte leakage as compared to their controls kept at 0°C for 10 d.Scientific Journal Series Paper No. 13842 of the Minnesota Agricultural Experiment Station, St. Paul, Minn     

Characterization of Aeromonas salmonicida variants with altered cell surfaces and their use in studying surface protein assembly

Aeromonas salmonicida variants were characterized for alterations in their cell surface structure and used to examine reconstitution of the surface protein layer (A-layer). Variants lacking outer membrane O-polysaccharide were devoid of A-layer and excreted stainable floret-like material of the surface protein (A-protein). One variant, showing partial loss of O-polysaccharide, was associated with a disrupted A-layer and excretion of some A-protein. Variants lacking A-protein but possessing O-polysaccharide rapidly absorbed and concentrated sufficient excreted A-protein at the cell surface to coat the cells with a single confluent layer. Although differences in electrophoretic mobilities of A-proteins and O-polysaccharides from typical and atypical strains were evident, the different A-proteins and A-protein-deficient variants were interchangeable for reconstitution of a surface protein layer. No association of A-protein with cell surfaces of unrelated gram-negative bacteria was observed.Abbreviations A-layer additional surface protein layer - A-protein surface protein - Ast Aeromonas salmonicida typical - Asa Aeromonas salmonicida atypical - A^- phenotypically A-protein-negative variant - O^- phenotypically O-polysaccharide-negative variant - O^wk phenotypically O-polysaccharide weak variant - BHI brain heart infusion - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis - TEM transmission electron microscopy     

A model of associative memory in the brain

A model of associative memory for time varying spatial patterns is proposed and simulated on a digital computer. This is a network composed of many neuron-like elements, and shows an ability for associative memory similar to that of the brain.Suppose a number of sequences of spatial patterns are presented to this network, for example, 12345, ABC, and so on. Then, these patterns are memorized in the network. After that, if any part of one of these sequences, say 23, is presented to the circuit, the rest of the sequence, 45, is recalled following to it. It resembles to such a situation — if we hear a part of a melody which we have memorized in the past, the rest of the melody is recalled even after it is stopped half-way. Although the recalled patterns are not always 100% correct, they are not completely destroyed even if the presented patterns are imperfect.     

Differential molecular responses to abscisic acid and osmotic stress in viviparous maize embryos

Substantial quantities of mRNA encoding the abundant Em polypeptide accumulate, in planta, in developing embryos of maize (Zea mays L.). By contrast, accumulation of Em mRNA is only barely detectable in embryos with the vp-5/vp-5 genotype [an abscisic acid (ABA)-deficient viviparous phenotype]. Em mRNA is not detectable within viviparous embryos of the vp-1/vp-1 genotype that are non-responsive to ABA. Culture of immature wild-type and vp-5/vp-5 embryos in the presence of exogenous ABA or of an osmotically active agent prevents precocious germination and results in expression of the Em genes. When vp-1/vp-1 embryos are cultured under similar conditions, only the application of osmotic stress prevents precocious germination. However, Em mRNA does not accumulate either in ABA-treated or stressed, arrested embryos, indicating a requirement for ABA perception through a VP-1-mediated mechanism for Em gene expression. Nevertheless, vp-1/vp-1 embryos do show both ABA and stress responses at the molecular level. Treatment with ABA causes the accumulation of mRNA encoding a polypeptide of approx. 30 kDa, whilst osmotic stress induces the accumulation both of a 30-kDa polypeptide and a set of approx. 20-kDa polypeptides. This indicates the existence of discrete, parallel ABA and stress response pathways in developing maize embryos.Abbreviations ABA abscisic acid - cDNA copy-DNA - DAP days after pollination - kDa kilodaltons - MS Murashige and Skoog medium - LEA late embryogenesis abundant - NEpHGE non-equilibrium pH gradient gel electrophoresis - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Fertility ofFusarium moniliforme from maize and sorghum related to fumonisin production in Italy

Forty-three strains ofFusarium moniliforme isolated from infected maize and sorghum plants in Italy were assayed for their ability to produce fertile crosses with A and F mating population tester strains, in relation to their ability to produce fumonisins on maize substrate. Most of the strains isolated from maize (ear and stalk rot and maize-based feed), producing fumonisin B₁ (FB₁) and B₂ (FB₂) (up to 4,100 and 855 mg/kg, respectively), belonged to the A mating population. All of the strains isolated from sorghum belonged to the F mating population and produced little or no FB₁ and FB₂. This is the first report of the occurrence of mating population F in Europe. Our data on strains from Italy are consistent with previous studies from the United States that found significant differences in sexual fertility and fumonisin production between strains from maize and sorghum.     

Zur Dynamik feiner Pseudopodien von Hochmoor-Amöben

Zusammenfassung Es werden verschiedene Vorgänge an sehr zarten Pseudopodien beschrieben und mit Hilfe der an submikroskopischen Fibrillen (schraubig gebauten Mikrofibrillen und Mikroröhrchen der Elektronenmikroskopie) auftretenden Torsionsspannungen und Rotationen gedeutet.

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On the dynamics of slender pseudopodia of bog amebae

Summary Different processes which occur on very slender pseudopods are described. They are interpreted with the help of torsional forces and revolutions of the submicroscopic fibrils (helical microfibrils and microtubules in electron microscopy).

     

The adaptive significance of cultural behavior: Comments and reply

Summary Fundamentally, theoretically, there is only one process underlying genetic and cultural evolution: natural selection. Organism fitness-enhancement (adaptive significance) is one of its practical mechanisms; group formation and maintenance is another, often but not always through fitness-enhancement; and need-fulfillment is still another. If Durham can accept that formulation, and switch from organism-thinking to instruction-thinking (Cloak, 1975: 178), he will free himself from two handicaps: First, he can forget his worries about reductionism and determinism (1976a: 100, 101). Under this general theory of natural selection, cultural evolutionis biological evolution, continued by other (nongenetic) means. Second, he will spare himself the appearance of anthropomorphism, mentalism, and wishy-washiness attendant on his discussion of kinds of significance, other than adaptive significance, of cultural behaviors (1976a: 102–106, 115).     

Contextualizing Images in Dreams and Daydreams

A contextualizing image (CI) is a powerful central image of a dream which appears to contextualize (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, I was overwhelmed by a tidal wave. This appears to picture their feeling of terror and/or vulnerability.A scoring system for CIs is examined here and is applied to dreams and daydreams supplied by 40 students. Two raters scoring dreams on a blind basis showed good inter-rater reliability. Recent dreams were shown to have more as well as more intense CIs than recent daydreams; likewise, dreams that stand out had more intense CIs than daydreams that stand out. Students with thin boundaries had more and more intense CIs than students with thick boundaries in their recent dreams and nightmare, but not so clearly in dreams and nightmares that stand out. The emotions judged as contextualized by the powerful images tended towards fear/terror and helplessness/vulnerability in dreams (especially in dreams that stand out) whereas emotions contextualized by images in daydreams showed a wide range with no clusters.     

Memorization and delayed expression of regulatory messages in plants

Plantlets of Bidens pilosus L., considered to be basically symmetrical, can be lateralized (A/B) by being administered a symmetry-breaking signal such as puncturing one of the plant cotyledons. The induced asymmetry remains latent as long as the plants have not been made permissive, i.e. as long as the plant apex is left functioning. When the apex has been removed (plant decapitation), the latent asymmetry is expressed by one of the cotyledonary buds (a/b) statistically beginning to elongate before the other. The interval of time between delivering the symmetry-breaking signal and making the plant permissive is the memorization-time, t. Memorization can be quantified by using a precedence index, q, the values of which range from 0 (no detectable asymmetry with regard to bud growth) to ±1 (bud growth perfectly asymmetric in favour of either bud b or a). Even for memorization times, t, up to 14 d, q-values up to 0.4 (or even larger) are observed. Various experimental characteristics (e.g. light, temperature, presence or absence of the root system) but not the plant age can affect the q-values, at the moment when the treatments are performed, at least in the range of 6 to 25 d. Combining several puncturing treatments either increases or decreases the q-values, depending on the nature of these treatments and the time-intervals, t, between them. Symmetrically removing both cotyledons in the minutes following the puncturing of one of them does not significantly alter the results, which means that the symmetry-breaking message is rapidly transported and memorized within the plant. Non-traumatic asymmetrical treatments (droplets of saline solutions, light-gradients) can also act as symmetry-breaking signals and be memorized. Plants other than Bidens are likely to possess similar memorization ability, although the q-values observed up to now have not been very large.     

Protoplasmic streaming in the giant unicellular green algaAcetabularia mediterranea

Summary Protoplasmic Streaming inAcetabularia mediteranea has been studied by microcinematography in 1. germinating zygotes, 2. germlings before the differentiation of rhizoids and apices, 3. young cells with rhizoids and apices, 4. vegetative cells-several centimeters in length, 5. cells with a maximum sized cap, containing secondary nuclei, and 6. cells after cyst formation. Intracellular transport is found to occur at a network-system of thin filaments and at a different system of headed streaming bands. At the network of filaments chloroplasts are found to move at a velocity of 1–2 m/sec. Headed streaming bands move along the filaments and may lead without interruption from the rhizoid to the apex of the cell andvice versa. The front zone of the streaming bands is occupied by a leading cytoplasmic head-structure. Small vesicles, polyphosphate granula and secondary nuclei are the predominant moving structures in headed streaming bands. The velocity of these particles is found to be 3–11 m/sec. The filament system is found during all developmental stages. Headed streaming bands are undetectable in germinating zygotes and develop from small cytoplasmic droplets in germlings to broad heavily loaded bands in the huge vegetative cell.Transport of secondary nuclei by headed streaming bands is not observed during mitotic divisions and after cyst formation, though moving bands are still present for several weeks after cyst formation.     

Interaction sites on phosphorylase kinase for calmodulin

Holophosphorylase kinase was digested with Glu-C specific protease; from the peptide mixture calmodulin binding peptides were isolated by affinity chromatography and identified by N-terminal sequence analysis. Two peptides originating from the subunit, having a high tendency to form a positively charged amphiphilic helix and containing tryptophane, were synthesized. Additionally, a homologous region of the subunit and a peptide from the subunit present in a region deleted in the isoform were also selected for synthesis. Binding stoichiometry and affinity were determined by following the enhancement in tryptophane fluorescence occurring upon 1:1 complex formation between these peptides and calmodulin. Finally, Ca²⁺ binding to calmodulin in presence of peptides was measured. By this way, the peptides 542–566, 547–571, 660–677 and 597–614 have been found to bind specifically to calmodulin.Together with previously predicted and synthesized calmodulin binding peptides four calmodulin binding regions have been characterized on each the and subunits. It can be concluded that endogenous calmodulin can bind to two calmodulin binding regions in as well as to two regions in and . Exogenous calmodulin can bind to two regions in and in . A binding stoichiometry of 0.8mol of calmodulin/ protomer of phosphorylase kinase has been determined by inhibiting the ubiquitination of calmodulin with phosphorylase kinase. Phosphorylase kinase is half maximally activated by 23nM calmodulin which is in the affinity range of calmodulin binding peptides from to calmodulin. Therefore, binding of exogenous calmodulin to activates the enzyme. A model for switching endogenous calmodulin between , and and modulation of ATP binding to as well as Mg²⁺/ADP binding to by calmodulin is presented.