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An automated system is described for computer examination of the mass spectrum of an unknown mixture for the presence of a specific compound. The probability that the compound is present is indicated as a 'confidence index' K; 2 K should signify the average number of compounds, selected at random, whose mass spectra would have to be examined to find data which match the target spectrum to the same degree as does the unknown. The value of K is determined by the uniqueness U of the m/ e value, the abundance A, and the criterion of abundance agreement W of the matching peaks, and of the compound concentration D in the sample. Application to spectra from a variety of compounds, including illicit drugs, indicates that the system has high sensitivity and selectivity, and that the value of K is a useful index of the reliability of the identification. Initial testing of this system has utilized an automated quadrupole mass spectrometer under control of a dedicated microcomputer with sample introduction through a flash evaporator and membrane separator. [ABSTRACT FROM AUTHOR]

A defective phage Φ 80.1 was obtained which carries an amber suppressor locus ( su, most likely identical to su of Brenner and Beckwith, 1965) and part of the tryptophan operon from E. coli K 12. Various homo- and heterogenotes with respect to this suppressor locus have been isolated. The action of the amber suppressor locus on amber sites in the decarboxylase gene of the pyruvate dehydrogenase complex and on T 4 amber mutants was tested. In all cases the suppressor in its active state ( su; i. e., suppressing amber sites) was dominant over the suppressor in the inactive ( su) state. The presence of another amber suppressor ( su) in the host did not alter the expression of su towards T 4 amber mutants. Further evidence was obtained for the specificity of the amber suppression. While remaining unsuppressed in strains harboring su, two amber sites of the O-type in one of the pyruvate dehydrogenase genes are suppressed by su in heterogenotes su/ su. The kinetics of the expression of the suppressor locus after infection with the defective Φ 80.1 carrying su was tested and compared for the production of pyruvate dehydrogenase and T 4 amber mutants. Comparable rates of suppressed synthesis of the enzyme appeared to be reached much later than the formation of T 4 amber mutants. [ABSTRACT FROM AUTHOR]

Larvae and adults of the aphid Myzus persicae (Sulz.), reared on a synthetic diet, gain higher weight if their diet contains ATP (1.11 μ M). The numbers of larvae born on diets with ATP are higher (20%) than on diets without ATP. The longer aphids were fed on the ATP-diet the more their weight increased compared with larvae on a diet without ATP. Generally ATP seems to balance the synthetic diet in whatever physiological way it may be. Since phloem sap contains a high level of ATP, it is suggested that ATP may also be of great importance under natural conditions on the host-plants. [ABSTRACT FROM AUTHOR]

Auxin transport in corn coleoptile sections was inhibited by 2,3,5-triiodobenzoic acid (TIBA) as well as by 1-N-naphthylphthalamic acid (NPA); this inhibition was effected within 1 min of application.A particulate cell fraction-presumably plasma-membrane vesicles-specifically binds NPA and properties of these binding sites were studied using (3)H-NPA and a pelletting technique. The saturation kinetics of the physiological NPA effect, i.e. the inhibition of auxin transport, is similar to that of the specific in-vitro NPA binding. Half saturation of the inhibitory effect was found with about 5×10(-7) M TIBA and with 10(-7) M NPA. Both substances also decreased the speed of movement of auxin pulses within coleoptile sections.NPA dissociates from its binding site when the particulate cell material is centrifuged through an NPA-free cushion. The NPA that is washed from its binding site can be used in another binding test without any apparent change and is chromatographically unaltered. Therefore, the NPA binding is probably reversible and non-covalent. Inhibition of auxin transport by TIBA or NPA could also be reversed when the coleoptile sections were washed in buffer.The movement of (131)I-TIBA in corn coleoptiles appears to be polar in a basipetal direction. Higher concentrations of indoleacetic acid or TIBA inhibited this polar movement, suggesting that TIBA moves in the same channels as auxin. With (3)H-NPA, however, no polar transport could be detected. Together with the in-vitro binding results, these data indicate that TIBA acts directly at the auxin receptor while NPA has a different receptor site.The effect of TIBA and NPA on elongation, with or without auxin, is neglegible in comparison to their effects on auxin transport.

Wild-type corn coleoptiles showed an initial downward bending upon transfer from the vertical to the horizontal position. Strong upward curvature started only 15-30 min after the begin of horizontal exposure.Little, if any at all, initial downward geotropic bending was found with amylomaize coleoptiles at 1 X g. With stronger stimuli (10 or 20 X g) the amylomaize mutant reacted initially strongly in the "wrong" direction, i.e. opposite to the later response.When wild-type coleoptiles had been symmetrically prestimulated for 60 min with alternating 2-min horizontal exposures from opposite sides, no initial downward bending occurred if the plane of horizontal exposure was maintained from pretreatment to the continuous horizontal stimulation of the test. If, however, the coleoptiles were rotated 90° around their long axis between pretreatment and test, the initial downward bending reaction developed as in the non-prestimulated controls. Thus changes in reactivity remained localized to the site of stimulation.Following the same pretreatments used for the curvature measurements, lateral (3)H-IAA transport was measured in coleoptile segments for 10 or 12.5 min. The auxin distribution found was strikingly parallel to the bending for all pretreatments.The dependence of reaction pattern on the duration of prestimulation in the same plane was tested. The function indicates a "half life" of 10-20 min for the change in sensitivity. The findings are discussed in view of a model of overstimulation and adaptation.

The early time course (0-30 min) of the action of auxin (3-indoleacetic acid) on the elongation of segments from corn coleptiles was studied, using a high-resolution continuous recording technique. Two different effects of auxin were observed: (1) After addition of low auxin concentrations (2 x 10(-7)M) to 4-mm sections, a very rapid (2-3 min) enhancement of elongation was found. Similar early responses were seen following the addition of low concentrations of the methyl ester of indoleacetic acid. (2) Following a large step-up in the auxin level (10(-5), 10(-4), or 10(-3)M), a rapid transient decrease was observed one to three minutes after the addition of indoleacetic acid. It lasted 10-15 minutes at which time the steady rate of auxin-promoted elongation became evident. Similar kinetic patterns of auxin effects other than on elongation and the implications of the findings on hypotheses of the primary action of auxin are discussed.

Movement of radioactive auxins was analysed in corn coleoptile sections. The results support the idea that processes involved in the transport of indoleacetic acid (IAA) are specific for growth-promoting auxins.Inhibition of IAA transport by triiodobenzoic acid is caused by a reversible block of the exit; the auxin held back remains in the transport pool. The observed increase in immobilization may be a secondary effect caused by the increased concentration of free IAA in the tissue.Auxin molecules are most likely transported by anon-covalent mechanism. IAA and naphthaleneacetic acid (NAA) move through the cell and exit as free molecules. A search for a transient auxin complex, chaseable as required for any transport carrier intermediate, yielded negative results. No(18)O was lost from NAA labeled with(18)O in the carboxyl group during transport of the auxin through coleoptile tissue.After application of IAA to auxin-depleted tissue, the transport rate undergoes oscillations with a period length of ca. 25 min.The movement of the auxin 2.4-dichlorophenoxyacetic acid which is usually sluggish, increased several times if some IAA was added. Auxin, thus, stimulates its own transport.A model is discussed in which auxin-binding to the plasma membrane and reversible changes of membrane conformation may provide a basis for active secretion and for the observed cooperativity.

Auxin transport was studied in coleoptile sections that were stimulated geotropically. The early time course of auxin-transport asymmetry was measured. An initial phase in which more IAA was delivered into the receptor for the upper half was found after 5 min of horizontal exposure. After about 15 min this was followed by the expected known asymmetry in which more auxin flows in the lower side of the coleoptile. Upon return of the coleoptile to a vertical position, this asymmetry disappeared within 30 min.Earlier correlations of geosensitivity of the auxin transport system with sedimentation of amyloplasts in comparisons of wild type corn and an amylomaize mutant were confirmed and extended. It was also shown that, in contrast to the geotropic effect, phototropically induced lateral auxin asymmetry was not significantly different in wild type and amylomaize. Eleven other single-gene endosperm starch mutants of corn were compared to their corresponding normals. In all pairs, if a difference in geosensitivity of lateral auxin transport was present, it was correlated with a parallel difference in amyloplast sedimentation: e.g., sugary 1 ("67") had an amyloplast asymmetry index of 0.32 and a 13% gravity effect on auxin transport; the paired wild-type had both a greater amyloplast asymmetry (0.61) and a greater gravity effect on transport (23%).Correlations between gravity effects on auxin transport and amyloplasts were also shown in comparisons of apical and basal sections of corn, oat and Sorghum coleoptiles.Further results, confirming the increased effect of centrifugal acceleration greater than 1xg on lateral auxin transport and on curvature, are in agreement with the hypothesis that the pressure exerted by amyloplasts, acting as statoliths, locally stimulates the auxin transport system in the individual cells.

Inversion of corn coleoptile sections resulted in a 10-20% inhibition of basipetal transport of 3-indoleacetic acid (IAA) and a more pronounced inhibition (20-50%) of the transport of 1-naphthaleneacetic acid (NAA).The effect of inversion on basipetal NAA transport was compared in wild-type corn and in the amylomaize mutant which contains smaller and slower sedimenting amyloplasts: the gravity induced inhibition was higher in the wild type coleoptiles (27% versus 9%).In wild type the inhibitory effect on basipetal NAA transport appeared within less than 30 min after inversion; then the effect remained relatively constant over at least 2 hr of transport. When the sections were returned to the upright position the transport rate increased, reaching the level of upright controls within 30 min.An effect of gravity on lateral transport of NAA was also demonstrated and shown to be expressed within 10 min after placing the tissue horizontally.When basipetal transport was tested in the direction of gravity and/or centrifugal acceleration, auxin movement incrased with increasing acceleration. Transport against centrifugal acceleration (10 x g) was less than transport of control sections (inverted at 1 x g).The results agree with the hypothesis that starch statoliths act by a pressure mechanism on the membrane transport system of auxin.