Growth of Photoheterotrophic Cells of Peanut (Arachis hypogaea L.) in Still Nutrient Medium

Cell suspension cultures were established from the callus proliferation of leaf explants of 10- to 12-day-old seedlings of the peanut (Arachis hypogaea L. var. TMV-3). The cells could be cultivated in both agitated and still media, the latter promoting more of chlorophyll (Chl) synthesis. High Chl content (210-240 micrograms Chl per gram fresh weight), yield of free and pipetable cells, presence of all the pigments in the same ratio as that of the leaf tissue, and high rates of O₂ evolution (140-170 micromoles O₂ per milligram Chl per hour) were some of the desirable features of the still-grown cell cultures. However, considerable variations with regard to the above characters were observed between the cell cultures of different varieties of the peanut.

O₂ evolution by the cultured cells was dependent on exogenous supply of HCO₃⁻. A well-developed photosynthetic apparatus as evidenced from photosystem I and photosystem II activities of the isolated chloroplasts and variable fluorescence measurements with the cell cultures was further documented by electron microscopic evidence of distinct granal stackings in chloroplasts and sodium dodecyl sulfate-polyacrylamide gel separation of thylakoid membranes into P700 Chl a protein complex and light-harvesting Chl a/b complex. Evidence is presented for the relative increase in the Chl associated with P700 Chl a protein complex in contrast to the light-harvesting Chl a/b complex in the cultured cells as compared to intact leaf.

     

Carbon Assimilation in Photoheterotrophic Cells of Peanut (Arachis hypogaea L.) Grown in Still Nutrient Medium

The relative transport of photosynthetic and dark carboxylation products in photoheterotrophic cells of Arachis hypogaea L. var. TMV-3 at varied phases of growth were determined. Despite the presence of an equally competent photosynthetic apparatus as determined from ¹⁴CO₂ incorporation rates in the dark and light, pulse-chase experiments revealed little or no change in the radioactivity of the C₃ intermediates but rapid disappearance of label from the dark carbon assimilates (malate and other tricarboxylic acid cycle intermediates) with a simultaneous increase in the aminoacid pool in early log-phase (10 days old) cells. However, significant flow of carbon through the photosynthetic intermediates resulting in the accumulation of sugars occurred in the late log-phase (34 days old) cells. Limitation of exogenous sugar in the nutrient milieu and depletion of reserve carbohydrates stored in starch of the chloroplasts of the cells were considered as the decisive factors in promoting transport of C₃ cycle intermediates through the reductive pentose phosphate pathway in photoheterotrophic cells. The observed drain of radioactivity even from the small amounts of tricarboxylic acid cycle intermediates synthesized during photosynthesis into glutamate indicated that the transport of carbon through the nonautotrophic pathway is not controlled by these factors.     

Detection of signs of estrus in the charolais cow and its Brahman cross under continuous observation

In order to study the characteristic signs of an induced estrus in beef cattle maintained in the tropics, 31 animals, 16 pure Charolais and 15 Charolais/Brahman cross, were continuously observed during the first 100 hours following prostaglandin injection. The animals were pastured in a field of approximately 3 hectares. A highly significant relationship (P < 0.01) seemed to exist between behavioural tendencies and the interval following the onset of estrus. Behaviour included butting, attempts to mount, smelling of genitalia (active) and allowing to be mounted and have genitalia smelled (passive). No consistant pattern of sexual activity could be established since some animals were more active than others. Mounts were observed to occur between 6 and 9 in the morning (33%), 9 and 12 at night (16%) and midnight and three in the morning (13%). Differences existed between the Charolais and the Brahman cross with respect to the number of mounts (P < 0.05) and in the response to an induced estrus (P < 0.05). No correlation was found between grazing habits and sexual activity, the former expressed as the number of animals standing up during each hour.     

Fast freezing of cow embryos in French straws with an automatic program

Cow embryos between day 6.5 and 9 were frozen in 1.5M DMSO in PBS at 2 degrees C/min from seeding to -25 degrees C before being plunged into liquid nitrogen directly or after 10 min at -25 degrees C. Cooling rate from 20 degrees C to -5 degrees C was 9 degrees C/min. Seeding was induced automatically at -5 degrees C by injection of liquid nitrogen vapour. Embryos were subsequently thawed by direct transfer to water at 20 degrees C (group I) or at 37 degrees C (group II). Survival was assessed by culture in vitro and by transfer. In group I, 35.7% were degenerated after thawing (compared to 35.4% in group II). Survival rate after culture in vitro for 24h was not significantly different (48.3% vs 42.8%) and hatching rate after 96h culture was quite similar (33.3% vs 34.4%). In group II, four pregnancies were obtained from 10 embryos transferred. Time at -25 degrees C did not improve the results. Automatic seeding did not impair survival. These results show that the quality of the embryo is the determinant factor for survival after freezing and that the plastic straw is the most suitable vessel for freezing, storage and transfer of embryos.     

Effects of prolonged omnilateral gravistimulation on the ultrastructure of statocytes and on the graviresponse of roots

Statocytes of vertically growing roots of Lepidium sativum L. exhibit a strict polarity: The nucleus is positioned near the proximal periclinal cell wall, amyloplasts are sedimented on a complex of rough endoplasmic reticulum (ER) consisting of parallel cisternae near the distal periclinal cell wall.When 24 h old, vertically grown roots are rotated for an additional 20 h on a horizontal clinostat, this polarity is destroyed. Furthermore, the prolonged omnilateral stimulation leads to a damage of the statocytes, which in some cases ends in the self-destruction of the sensitive cells. The different components of the ultrastructural respones of the statocytes are: Displacement of the nucleus; changes in amount and distribution of the ER; loss of amyloplast starch; confluence of lipid droplets to large aggregates: a considerable increase of the lytic compartment. In addition, even anticlinal cell walls may be lysed up to small stumps. As all these effects are clearly restricted to the statocytes, only these cells are able to respond to the continuously changing direction of the gravity vector, thus perceiving gravity as such.After being exposed horizontally, the graviresponse of rotated roots is delayed as compared to the controls. About 20% of the rotated roots do not respond (curve) at all, but grow perpendicular in relation to the gravity vector. Perception of gravity is inevitably correlated with the polarity and the integrity of the statocytes.Abbreviation ER endoplasmic reticulum A preliminary report was presented at the Fall Meeting of the German Society for Cell Biology in Salzburg, Austria, September 1979 (Hensel and Sievers 1979)This paper represents part of a dissertation (D 5) of W. H.     

Identification of Selenocysteine in the Proteins of Selenate-grown Vigna radiata

Selenocysteine, the selenium analog of cysteine, was identified in proteins of Vigna radiata (L.) Wilczak grown with selenate. To stabilize selenocysteine and prevent its breakdown, the carboxymethyl derivative was synthesized by the addition of iodoacetic acid to the protein extract from [⁷⁵Se]selenate-grown plants. A ⁷⁵Se-labeled component of the carboxymethylated protein hydrolysate possessed chromatographic properties identical to those of a ¹⁴C-labeled carboxymethylselenocysteine standard during paper and thin layer chromatography and during gel-exclusion, anion-exchange, and cation-exchange column chromatography. Detection of selenocysteine in proteins of a selenium-sensitive plant, and the possibility that the presence of this compound alters normal functions, provides an explanation for the toxic effects of selenium.     

Interaction between External and Internal Conditions in the Development of Photosynthetic Features in a Grass Leaf: I. REGIONAL RESPONSES ALONG A LEAF DURING AND AFTER LOW-LIGHT OR HIGH-LIGHT ACCLIMATION

Morphological and functional features were compared along a developing third leaf and fully expanded leaf from high-light- and low-light-acclimated seedlings of Lolium multiflorum.     

Growth of Aeromonas hydrophila at Low Concentrations of Substrates Added to Tap Water

The ability of an Aeromonas hydrophila isolate obtained from filtered river water to grow at low substrate concentrations was studied in batch experiments with tap water supplied with low concentrations of substrates. Growth was assessed by colony count determinations. The isolate only multiplied in the used tap water (2 to 3 mg of dissolved organic carbon per liter) after the addition of a small amount of an assimilable carbon compound. d-Glucose especially caused growth of the organism even at initial concentrations below 10 mug of C per liter. At initial glucose concentrations below the K(s) value (12 mug of C per liter), generation times and yield (colony-forming units per milligram of substrate-C) were nonlinear with 1/initial glucose concentrations and initial glucose concentrations, respectively. From these observations, the maintenance coefficient m was calculated (m = 0.015 mg of glucose per mg [dry wt] per h at 12 degrees C). At initial concentrations below the K(s) value of starch (73 mug of C per liter), no growth was observed, but complete use of starch occurred in these situations after the addition of 10 mug of glucose-C per liter. The results of this study show that information of ecological significance may be obtained by very simple batch experiments. Moreover, the isolate studied may be used in growth experiments to assess the maximum concentration of glucose which might be present in water, particularly tap water.     

Spatiotemporal behaviors in immobilized enzyme systems

The immobilization of enzymes within an artificial membrane, with a homogeneous distribution of the active sites, allows a simple modelling in a well defined context. The systems are described by non-linear PDE'S, taking into account enzyme reaction and metabolite diffusion. These equations can exhibit several types of behaviors, qualitatively different from those observed in solution, such as hysteresis, oscillations and pattern formations. Preliminary experimental results have shown the existence of sustained oscillations and instabilities with immobilized acetylcholinesterase and phosphofructokinase.     

Effect of Ethylene and Oxygen on the Development of Cyanide-resistant Respiration in Whole Plant Mitochondria

Mitochondria from whole potatoes (Solanum tuberosum) ordinarily fail to oxidize respiratory substrates and to consume molecular O₂ in the presence of cyanide. Mitochondrial preparations obtained from tubers previously held for 24 hours in ethylene (10 microliters per liter) in air are only partially inhibited by cyanide. Application of ethylene in 100% O₂ led to an additional increase in the resistance of the mitochondrial respiration to cyanide. The resistance to cyanide was accompanied by a decrease in the respiratory control but no change in oxidative phosphorylation as shown by the measurement of ATP synthesis.