Glandular trichome exudate is the critical factor in geranium resistance to foxglove aphid

Resistance to the foxglove-aphid (Acyrthosiphon solani Kaltenbach) has been demonstrated in some inbred geranium lines (Pelargonium Xhortorum Bailey). To establish more definitively the cause/effect relationship between tall glandular trichome exudate and resistance, an intact plant bioassay was performed comparing a resistant plant line, a resistant plant line from which the tall glandular trichome exudate had been removed using a basic buffer solution, a susceptible line and a susceptible line treated with the buffer wash. After 5 days of isolation on the respective surfaces, the number of surviving adult aphids as well as the number of nymphs produced and remaining alive were determined. Aphids on the buffer washed, resistant line exhibited mortality and fecundity which was not significantly different from that produced by the susceptible line. In contrast, the untreated resistance line was clearly resistant with lower adult survival and fewer living nymphs. The tall glandular trichome exudate must therefore be a critical factor in geranium resistance to the foxglove aphid.

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Zusammenfassung Widerstandsfähigkeit dem Fingerhut-Blattlaus (Acyrthosiphon solani Kaltenbach) gegenüber wurde in einigen durch Inzucht erzeugten Pelargonie-Linien (Pelargonium Xhortorum Bailey) gezeigt. Um das Verhältnis von Ursache und Wirkung zwischen dem hochgewachsenen glandulären Trichom-Exudat und Widerstandsfähigkeit genauer zu bestimmen, wurde eine Bio-Untersuchung an intakten Pflanzen unternommen. Dabei wurden eine widerstandsfähige Pflanzenlinie, eine widerstandsfähige Pflanzenlinie, von der das hochgewachsene glanduläre Trichom-Exudat durch eine basische Pufferlösung entfernt worden war, eine anfällige Linie und eine mit Pufferlösung behandelte Linie verglichen. Zwei erwachsene weibliche Blattläuse wurden fünf Tage durch ein engmaschiges Netz auf den zu untersuchenden dritten und vierten Knotenblättern eingesperrt. Bei jeder Pflanze wurde die Untersuchung an einem nichtbehandelten Blatt und an einem Blat, von dem das Exudat durch Waschen mit der Pufferlösung entfernt worden war, durchgeführt. Für jede Linie wurden fünf Pflanzen gebraucht, und der ganze Versuch wurde sechsmal wiederholt. Nach einer fünftägigen Isolierung auf den jeweiligen Oberflächen wurden die Blätter von der Pflanze entfernt, und sowohl die Zahl der überlebenden erwachsenen Blattläuse wie auch die der produzierten und noch am Leben gebliebenen Nymphen festgestellt. Mit einer niedrigeren Überlebensrate der Erwachsenen und weniger noch lebenden Nymphen war die nichtbehandelte widerstandsfähige Linie deutlich widerstandsfähig. Im Gegensatz dazu zeigten die Blattläuse auf der mit Puffer gewaschenen widerstandsfähigen Linie eine Sterblichkeit und Fruchtbarkeit, die nicht erheblich höher waren, als die auf der anfälligen Linie, was beweist, daß das Waschen mit der Pufferlösung den Widerstandsfaktor entfernt hatte. Das hochgewachsene glanduläre Trichom-Exudat muß deshalb ein kritischer Faktor in der Widerstandsfähigkeit gegen Pelargonie-Schädlinge sein.

     

Secondary transport of amino acids by membrane vesicles derived from lactic acid bacteria

Lactococci are fastidious bacteria which require an external source of amino acids and many other nutrients. These compounds have to pass the membrane. However, detailed analysis of transport processes in membrane vesicles has been hampered by the lack of a suitable protonmotive force (pmf)-generating system in these model systems. A membrane-fusion procedure has been developed by which pmf-generating systems can be functionally incorporated into the bacterial membrane. This improved model system has been used to analyze the properties of amino acid transport systems in lactococci. Detailed studies have been made of the specificity and kinetics of amino acid transport and also of the interaction of the transport systems with their lipid environment. The properties of a pmf-independent, arginine-catabolism specific transport system in lactococci will be discussed.Abbreviations pmf protonmotive force - transmembrane electrical potential - pH transmembrane pH gradient - PE phosphatidylethanolamine - PC phosphatidylcholine Paper adapted from a treatise Secondary Transport of Amino Acids by Membrane Vesicles Derived from Lactic Acid Bacteria and awarded the Kluyver Prize 1988 by the Netherlands Society of Microbiology.     

Impact of salt adaptation on esterified fatty acids and cytochrome oxidase in plasma and thylakoid membranes from the cyanobacterium Anacystis nidulans

During adaptation of photoautotrophically growing fresh water cyanobacterium Anacystis nidulans to high salinity the cells showed a pronounced increase of proton-sodium antiporter activity, and of cytochrome c oxidase in isolated and purified plasma membrane. At the same time the concentrations of plasma membrane-bound EDTA-resistant copper and iron (determined by inductively coupled plasma atomic emission spectrometry) rose proportionately, accompanied by an increase in whole cell respiration. In plasma membranes from salt adapted cells lipid/protein ratios were markedly higher than in control cells, levels of esterified saturated and long-chain fatty acids being significantly higher than the respective levels of unsaturated and short-chain fatty acids which explains the higher lipid-phase transition temperatures derived from Arrhenius plots. Immunoblotting of the membrane proteins with antisera raised against the cytochrome c oxidases from Paracoccus denitrificans and A. nidulans gave two cross-reacting bands with apparent molecular weights around 50000 and 30000 (subunits I and II, respectively) which were more pronounced in plasma membranes from salt adapted cells when compared to control cells. The protein pattern of plasma membranes from salt adapted cells also showed the appearance of bands at apparent molecular weights of 44000–48000 and 54000–56000 which might stem from the proton/sodium-antiporter in this membrane.Abbreviations CM cytoplasmic or plasma membrane - ICM intracytoplasmic or thylakoid membrane - cyt cytochrome - DCCD N,N-dicyclohexylcarbodiimide - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonate - ICP-AES inductively coupled plasma atomic emission spectrometry - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - EPR electron paramagnetic resonance spectrometry     

Alterations in synaptosomal neurotransmitter amino acids in “petit-mal” rats at a daytime and a nighttime

The synaptosoma fractions of 6 brain areas-olfactory tubercles (OT), frontal cortex (FC), striatum (Sr), amygdala (A), thalamus (Th), hypothalamus (Hy)-have been analyzed for their neurotransmitter amino acids (AA) content in Wistar rats exhibiting petit-mal epilepsy (PM-E) and in controls (C). The analysis was carried out at 11 p.m. (nighttime corresponding to the acrophase for the hourly number of spike-wave complexes) and at 11 a.m. (daytime). A day versus night rhythmicity is recorded for synaptosomal inhibitory AA in control and in PM-E rats. However, day versus night variations are more frequent and more prominent in C rats than in PM-E rats. Two day versus night variations exist only in PM-E rats: increases of GABA level in Sr and of Asp in Hy. Differences between PME-and C in synaptosomal AA content are more likely to be present during the nighttime. During this period lower AA values for PM-E rats are found for one or several inhibitory AA in OT, Th, and FC. It seems that the differences between PM-E and C concerning the inhibitory AA correlate with the number of spike-wave discharges. Only in one brain area is there a similar difference for PM-E and C during daytime and nighttime: a decreased GABA content for PM-E rats in OT. The decrease is larger in nighttime than in daytime. This difference may serve as a marker for this epileptic disorder. Moreover, it is in OT that the greatest number of PM-E versus C differences in synaptosomal neurotransmitter AA are observed. In view of these and former data, the existence of different alterations in synaptosomal neurotransmitter AA for different types of epilepsy is suggested.Abbreviations used GABA 4-aminobutyrate - Tau taurine - Gly glycine - Asp aspartate - Glu glutamate - Gln glutamine - OT offactory tubereles - FC fronto-parietal cortex - Sr striatum - A amygdala - Th lateral thalamus - Hy lateral hypothalamus - AA neurotransmitter amino acids - I inhibitory - E excitatory - C control rats - PM-E petit-mal rats     

Glutamate is the endogenous amino acid selectively released by rat hippocampal mossy fiber synaptosomes concomitantly with prodynorphin-derived peptides

The release of endogenous amino acids from depolarized rat hippocampal mossy fiber synaptosomes was investigated to assess the possible role(s) of glutamate and aspartate in mediating the excitatory mossy fiber synaptic input. The relative proportions of prodynorphin-derived peptides concomitantly released with amino acids were also determined to further characterize the biochemical basis for mossy fiber synaptic transmission. Of the 18 amino acids shown to be present in superfusate fractions by liquid chromatographic analysis, only glutamate was released at a significantly enhanced rate from K⁺-stimulated (35 mM KCl) mossy fiber nerve endings. The rates of glutamate and aspartate release were increased by 360±27% and 54±12% over baseline respectively. However, the K⁺-evoked release of glutamate was substantially more Ca²⁺-dependent (80%) than was the release of aspartate (49%). The veratridine (45 M)-evoked release of both acidic amino acids was entirely blocked by 1 M tetrodotoxin. Depolarization (45 mM KCl) also stimulated the release of the four prodynorphin (Dyn) products examined, in a rank order of Dyn B >> Dyn A(1–17) > Dyn A(1–8) >> Dyn A(1–13), with Dyn B efflux increasing by more than 5-fold over baseline values. These results suggest that the predominant excitatory amino acid in hippocampal mossy fiber synaptic transmission may be glutamate and that this synaptic input may be modulated by at least four different products of prodynorphin processing.The animals involved in this study were procured, maintained and used in accordance with the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals prepared by the Institute of Laboratory Animal Resources—National Research Council.     

Regional excitatory and inhibitory amino acid levels in epileptic El mouse brain

Inbred mutant El mice are highly susceptible to convulsive seizures upon tossing stimulation. The levels of excitatory (e.g. glutamate and aspartate) and inhibitory amino acids [e.g. -aminobutyrate (GABA)] were examined in discrete regions of stimulated El mice [El(+)] non-stimulated El mice [El(-)] and ddY mice, which do not have convulsive disposition. In comparison with ddY, a general increased levels of aspartate, glutamate, glutamine, and taurine were detected in brain regions of El(-). The levels of GABA and glycine were almost the same in ddY and El(-). Compared to El(+), the levels of aspartate, glutamate, glutamine, and GABA in El(-) were either the same or higher. In the case of taurine and glycine, the levels in El(-) were either the same or lower than El(+). Alanine is special in that El(-) have a higher level than El(+) in hippocampus but lower in cerebellum. Furthermore, while marked changes were registered in several brain regions, none of the amino acids investigated showed any significant differences in the hypothalamus of three different groups of mice.     

Modulation of phosphoinositide metabolism in rat brain slices by excitatory amino acids,arachidonic acid,and GABA

In rat brain slices the synthesis of [³H]phosphoinositides and the production of [³H]inositol monophosphate (IP₁) induced by norepinephrine (NE) were inhibited by glutamate. Calcium concentrations were varied to test if these inhibitory effects of glutamate were mediated by a calcium-dependent process. Although reducing calcium or addition of the calcium antagonist verpamil reduced the inhibitory effects of glutamate, these results were equivocal because reduced calcium directly decreased agonist-induced [³H]phosphoinositide synthesis. The inhibitory effects of glutamate were mimicked by quisqualate in a dose-dependent manner, but none of a variety of excitatory amino acid receptor antagonists modified the inhibition caused by quisqualate. It is suggested that glutamate activates a quisqualate-sensitive receptor (for which an antagonist is not available) and causes inhibition of phosphoinositide hydrolysis mediated in part by a direct or indirect inhibitory effect of calcium on phosphoinositide synthesis. Modulatory effects of arachidonic acid were examined because glutamate and calcium can activate phospholipase A₂. Arachidonic acid caused a rapid and dose-dependent inhibition of [³H]phosphoinositide synthesis and of NE-stimulated [³H]IP₁ production. A similar inhibition of the response to carbachol also occurred. The inhibition caused by arachidonic acid was unchanged by addition of inhibitors of cyclooxygenase or lipoxygenase. Activation of phospholipase A₂ with melittin caused inhibitory effects similar to those of arachidonic acid. Inhibitors of phospholipase A₂ were found to impair phosphoinositide metabolism, likely due to their lack of specificity for phospholipase A₂. Further studies were carried out in slices that were prelabelled with [³H]inositol in an attempt to separate modulatory effects on [³H]phosphoinositide synthesis and agonist-stimulated [³H]IP₁ production. Several excitatory amino acid agonists inhibited NE-stimulated [³H]IP₁ production. This inhibitory inter-action could be due to impaired synthesis of [³H]phosphoinositides because, even though the slices were prelabeled, addition of unlabelled inositol reduced NE-stimulated [³H]IP₁ production, indicating that continuous regeneration of [³H]phosphoinositides is required. In contrast to the inhibitory effects of the excitatory amino acids, gamma-aminobutyric acid (GABA) enhanced the response to NE in cortical and hippocampal slices. GABA also enhanced the response to carbachol in hippocampal and striatal slices and to ibotenic acid in hippocampal slices. Baclofen potentiated the response to NE similarly to the effect of GABA and baclofen partially blocked the inhibitory effect of arachidonic acid but did not alter that of quisqualate.Abbreviations AMPA -amino-3-hydroxy-5-methyl-4-isoxazolepropionic - acid AP₄ dl-2-amino-4-phosphonobutyric acid - BPB bromphenacyl bromide - BSA bovine serum albumin - CNQX 6-cyano-7-nitroquinoxaline-2,3-dione - DFMO -difluoromethylornithine - DIDS diisothiocyanotostilbene-2,2-disulfonic acid - EGTA ethyleneglycol-bis-N - N, N N-tetraacetic acid - GABA -aminobutyric acid - GDEE glutamate diethyl ether - -GG -glutamylglycine - IP₁ inositol monophosphate - IP₂ inositol bisphosphate - IP₃ inositol trisphosphate - NDGA nordihydroguaiaretic acid - NE norepinephrine - NMDA N-methyl-d-aspartate     

大鼠隔—海马通路损伤对海马内递质含量及酶活力的影响

单侧切断大鼠海马缴和部分穹窿可使海马部分去神经。损伤后7d,海马内胆碱能系统中乙酰胆碱(ACh)含量下降72.5%,胆碱乙酰基转移酶(ChAT)活力下降45.7%,胆碱酯酶活力下降52.2%,在单胺能系统中,去甲肾上腺素(NA)含量下降16.3%,多巴胺(DA)含量下降31.3%,5-羟色胺含量下降30.3%。在损伤过程中,海马内氨基酸含量没有改变。实验结果表明,海马缴和穹窿是脑内胆碱能和单胺能传入神经到达海马靶区的部分共同通路。     

A reevaluation of the amino acid sequence of human follitropin beta-subunit

A collaborative study from two laboratories has been undertaken to re-evaluate the human follitropin -subunit sequence (hFSH), since areas of uncertainty remain in the wake of two earlier reports. The first report was by Shome and Parlow (1974). The second, by Saxena and Rathnam (1976), proposed revisions for sequence not definitively placed in the first study, as well as some differences in other placements. We have re-examined the sequence of the hFSH with more recent methodology. This has led to revision of certain areas of the sequence and resolution of differences between the two earlier proposals. Specifically, an-Ile-Ser- is established at 21–22, Asp at 41, Arg at 44, Lys at 46, and Glu at 111. These were areas of disagreement in the earlier proposals. A definitive placement of the residues around tryptophan-27 has now been obtained by three laboratories. C-terminal heterogeneity was observed with subunits ending at residue 107, 109, or 111. N-terminal heterogeneity has been observed in all preparations examined to date. A significant population of molecules with a proteolytic nick between residues 38–39 is noted. This is very likely an artifact of the collection and processing. The preparations examined in the present studies showed no evidence of residues 112–118 proposed by Saxena and Rathnam.