Isolation and characteristics of Thiopedia rosea (neotype)

Four new strains of Thiopedia rosea were isolated in pure culture from blooms of platelet-forming purple sulfur bacteria in the top layers of the anoxic hypolimnia of two freshwater lakes. Individual cells of the new strains as well as of T. rosea strain 4211 were spherical to oval, nonmotile and contained gas vesicles in the central part. The predominant photosynthetic pigments were bacteriochlorophyll a and okenone. All strains were strictly anaerobic and obligately phototrophic. Optimal growth occurred at low light intensities of 100 E · m^-2 s^-1 (tungsten lamp); intensities above 150 E · m^-2 s^-1 inhibited growth completely. Photoautotrophic growth was possible at sulfide concentrations up to 0.6 mM; higher concentrations were inhibitory. Acetate, butyrate and valerate supported photoorganotrophic growth in the presence of bicarbonate and sulfide concentrations below 1 mM. Sulfide was required as a source of cellular sulfur because assimilatory sulfate reduction is lacking. All strains were assigned to the species Thiopedia rosea with strain 4211 as a neotype.Dedicated to Prof. Dr. H. G. Schlegel on the occasion of his 66th birthday     

Acetylene inhibition technique underestimates in situ denitrification rates in intact cores of freshwater sediment

Abstract Denitrification in intact sediment cores was measured by the acetylene inhibition technique and compared with the nitrate flux between water and sediment. Less than half of the nitrate-N consumed by the sediment could be recovered as nitrous oxide-N. The low recovery rate of nitrous oxide from intact sediment cores indicated losses of nitrous oxide by diffusion down to nitrate-free sediment layers, where reduction of nitrous oxide may take place. In sediment slurries 100% of nitrate-N could be recovered as nitrous oxide-N as long as the nitrate concentration in the liquid phase was above 10 μM. Nitrous oxide added to nitrate-free sediment slurries was reduced regardless of whether acetylene was present or not. Therefore denitrification may be significantly underestimated by this method.     

Glucose control of sucrose synthase in the maize scutellum

The in vivo amounts of UDPG, UTP, UDP and UMP, metabolites known to influence the activity of sucrose phosphate synthase (SPS) and sucrose synthase (SS), were measured throughout 5 hr incubations of scutellum slices in fructose or water, i.e. under conditions of sucrose synthesis or breakdown. Cytosolic concentrations were estimated assuming that these metabolites were confined to the cytosol. Within the estimated in vivo concentration ranges, UDPG, UTP and UDP had little effect on the in vitro SS activity, but glucose (100 mM) inhibited SS in the synthesis direction by 63–70% and in the breakdown direction by 86–93%. Glucose inhibition of SS was considerably less when saturating levels of substrates were used. Sucrose did not inhibit SS. It is concluded that during germination the glucose produced from starch breakdown in the maize endosperm enters the scutellum and inhibits SS, preventing a futile cycle and limiting SS participation in sucrose synthesis.     

Initial stages in the course of adventitious bud formation on embryos of Picea abies

Adventitious buds on embryos of Picea abies (L.) Karst. developed after a pulse treatment with 250 μ M benzyladenine (BA) of pH 5.5 for 2 h. Light and temperature regimes were not critical during the initial stages. Adventitious buds developed faster after a pulse treatment and the variation among different experiments was lower compared to when the embryos were cultured on media supplemented with BA. Various stages of the differentiation of adventitious buds were identified: stage 1 - appearance of meristematic centres (approximately the first two weeks); stage 2 - development of adventitious bud primordia (approximately the third week); stage 3 - adventitious bud development (from approximately the 4th to the 8th week). This system may be used for further studies on bud differentiation.     

Stoichiometric binding of diacylglycerol to the phorbol ester receptor

The major phorbol ester receptor is the Ca++-activated, phospholipid-dependent protein kinase C. Diacylglycerol stimulates protein kinase C in a fashion similar to the phorbol esters. Likewise, it inhibits phorbol ester binding competitively. Both results suggest that diacylglycerol is the/an endogenous phorbol ester analogue. Alternatively, the diacylglycerol might simply be acting to modify the phospholipid environment of the protein. If diacylglycerol were indeed functioning as an analogue, it should interact with the receptor stoichiometrically. This interaction can be quantitated by measuring the perturbation in apparent diacylglycerol binding affinity as a function of the ratio of diacylglycerol to receptor. We report here that 1,2-dioleoylglycerol interacts with the receptor with the predicted stoichiometry.     

Critical roles for juvenile hormone and its esterase+ in the prepupa of Trichoplusia ni

In the caterpillar Trichoplusia ni (Lepidoptera: Noctuidae) it has been demonstrated by allatectomy that the appearance of juvenile hormone during the prepupal stage is crucial for the successful larval-pupal ecdysis of most larvae. Application of juvenile hormone or juvenile hormone esterase inhibitors at key times disrupted normal development as well. Thus the subsequent disappearance of juvenile hormone is regulated by degradation by juvenile hormone esterase in addition to a hypothetical reduction in biosynthesis. This reduction in juvenile hormone titer in the prepupa is just as critical for normal development as was its previous appearance. These observations on the critical role of juvenile hormone in the prepupa are in contrast to observations in some other species. For instance, in the case of Manduca sexta (Lepidoptera: Sphingidae), juvenile hormone is considered only supplementary to the action of prothoracicotropic hormone in the postwandering stage and primarily is required for normal pupal development. It thus appears that even within the Lepidoptera the role of juvenile hormone in prepupal development can vary dramatically.     

Triadimefon reduces transpiration and increases yield in water stressed plants

The total free amino acid pools in radicles of watermelon seeds, investigated during imbibition of water at 25°C, were higher under the most (darkness) than under the least (continuous broad spectrum far-red light) favourable light regime for germination. When seeds were imbibed in an appropriate osmotic solution of PEG-6000 (fully suppressing germination), in darkness or under continuous red or far-red light, the biochemical analyses of the radicles after 1,2,3 and 4 days from the onset of imbibition show that while the total soluble sugar content remains rather constant in all treatments, significant changes are observed in the total free amino acid pools. After the first day, a considerable increase characterizes the "darkness" pool in contrast to a moderate one under red, while the "far-red" pool remains constant. Ultimately, at 4 days, the three pools are 190,142 and 123% of the 0 day radicle one. The qualitative free amino acid determination of the 4 day darkness and far-red pools shows a considerably increased percentage contribution of glutamic acid, arginine and citrulline in the "darkness" pool. The free amino acid increase in non-illuminated radicles may be correlated to germinability; moreover, it is evidently a phytochrome-mediated, pre-germinatory event, probably due to the hydrolysis of proteins (known to be rich in glutamic acid and arginine), stored in the radicle.     

Kinetics of Drug-Induced Changes in Dopamine and Serotonin Metabolite Concentrations in the CSF of the Rat

Cerebrospinal fluid (CSF) was removed at a constant flow rate of 1 microliter/min from the third ventricle of anesthetized rats. Every 15 min, CSF dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were determined by direct injection of CSF into a liquid chromatographic system coupled with electrochemical detection. Mean CSF concentrations of DOPAC, HVA, and 5-HIAA were 1.29 microM, 0.88 microM, and 2.00 microM, respectively. In order to determine the turnover rates of dopamine (DA) and serotonin, experiments using monoamine oxidase (MAO) inhibition were performed. Tranylcypromine (20 mg/kg i.p.) induced a sharp exponential decrease of CSF DOPAC, HVA, and 5-HIAA, with respective half-lives of 15.60 min, 16.91 min, and 77.23 min. Their respective turnover rates were 3.74, 2.22, and 1.18 nmol X ml-1 X h-1. m-Hydroxybenzylhydrazine (NSD-1015, 100 mg/kg i.p.) and monofluoromethyl-DOPA (100 mg/kg i.p.), two decarboxylase inhibitors, induced a slow exponential decrease of all three CSF metabolites. alpha-Methyl-p-tyrosine (250 mg/kg i.p.) also induced a slow exponential decrease of DOPAC and HVA. These decreases of CSF DOPAC and HVA induced by DA synthesis inhibitors may reflect the turnover of DA in vivo. Haloperidol (0.5 mg/kg i.p.) considerably enhanced CSF DOPAC and HVA without affecting 5-HIAA, confirming that dopaminergic receptors modulate DA neurotransmission in vivo. Haloperidol administered 1.5 h after NSD-1015 did not increase DOPAC and HVA, in contrast to reserpine (5 mg/kg i.p.) injected under the same conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Formation and Clearance of Norepinephrine Glycol Metabolites in Mouse Brain

To determine the degree of conversion of 3,4-dihydroxyphenylethyleneglycol (DHPG) to 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and the amount of DHPG eliminated unchanged from the brain, we have examined the kinetics of formation and disappearance of mouse brain MHPG and DHPG following clorgyline (10 mg/kg, i.p.) and/or tropolone (75 mg/kg, i.p.) treatment. During the first 10 min after tropolone, brain DHPG levels accumulated linearly at a rate of 1,300 pmol/g/h, whereas MHPG disappeared exponentially at a rate of 411 pmol/g/h. Following clorgyline administration, brain DHPG declined exponentially at a rate of 1,240 pmol/g/h. In contrast, the elimination of MHPG became a first-order process only when catechol-O-methyltransferase (COMT) was also inhibited in addition to monoamine oxidase. Thus, combined clorgyline and tropolone treatment resulted in an exponential decline of MHPG levels at a rate of 524 pmol/g/h, whereas DHPG levels were slightly but significantly elevated compared to control values. When the animals were treated with pargyline (75 mg/kg, i.p.) in combination with clorgyline and tropolone, brain DHPG and MHPG disappeared at rates of 40 and 660 pmol/g/h, respectively. The above observations suggest that mouse brain DHPG is cleared primarily through O-methylation with minimal direct elimination from brain. Assuming the disposition and clearance of norepinephrine metabolites are similar in mouse and human brain, peripherally measured DHPG in humans is likely derived principally from extracerebral sources and reflects peripheral sympathetic function.