Die Bedeutung der Züchtung des Lieschgrases (Timothee) auf Rostresistenz

Ohne Zusammenfassung     

Über den Einfluss der Temperatur auf die Kohlensäureassimilation bei zwei klimatischen Pflanzenrassen

Ohne ZusammenfassungMit 6 Textabbildungen.     

Geschlechtsumkehr beim Haushuhn

Ohne Zusammenfassung     

Central actions of somatostatin in the generation and control of breathing

The neuropeptide somatostatin is involved in many functions in the central nervous system as well as in the periphery. When it is centrally injected, an irreversible apnea is often developed. In the present review, we discuss the effects of somatostatin as the result of its actions at three levels of the respiratory neural network: a) by modulating the output of cranial or spinal motoneurons; b) by altering the genesis of the respiratory rhythm in the brainstem: and c) by regulating the chemosensory drive input into the respiratory pattern generator.     

Presynaptic mechanism of action induced by 5-HT in nerve terminals: possible involvement of ryanodine and IP3 sensitive 2+ stores

Although modulation of transmitter release by serotonin (5-HT) at crayfish neuromuscular junctions has been known since 1965, the mechanisms of action have not been established in this classical synaptic preparation. We show that injections of adenophostin-A (an IP3 analog) in the nerve terminals greatly enhances synaptic transmission. Exposure to ryanodine (Ry) produces a biphasic response: at low concentration it is excitatory and high concentration it is inhibitory. Likewise, a low concentration (1 microM) of caffeine enhances synaptic transmission, whereas a high concentration (10 mM) has little effect on transmission. The varied responses and sensitivity to Ry and caffeine suggest a Ca(2+)-induced Ca(2+)-release mechanism and/or the presence of an IP3-receptor within the terminal. Thus, it is likely 5-HT's response is due to activation of intracellular pathways, which subsequently release Ca2+ from internal stores.     

S100A9 deficiency alters adenosine-5'-triphosphate induced calcium signalling but does not generally interfere with calcium and zinc homeostasis in murine neutrophils

The two calcium- and zinc-binding proteins, S100A9 and S100 A8, abundant in myeloid cells are considered to play important roles in both calcium signalling and zinc homeostasis. Polymorphonuclear neutrophils from S100A9 ko mice are also devoid of S100A8. Therefore, S100A9-deficient neutrophils were used as a model to study the role of the two S100 proteins in the neutrophils's calcium and zinc metabolism. Analysis of the intracellular zinc level upon pyrithione and (+/-)-(E)-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexeneamide (NOR-1) treatment revealed no differences between S100A9-deficient and wildtype neutrophils. Similar, the calcium signals were not distinguishable from S100A9-deficient and wildtype neutrophils upon stimulation with platelet activating factor (PAF), thapsigargin or macrophage inflammatory protein 1 alpha (MIP-1 alpha), indicating despite their massive expression S100A8/A9 do neither serve as calcium nor as zinc buffering proteins in granulocytes. In contrast, stimulation with adenosine-5'-triphosphate (ATP) induces a significant stronger increase of the intracellular free calcium level in S100A9-deficient cells compared to wildtype cells. Moreover, the ATP-induced calcium signal was still different when the cells were incubated in calcium free buffer suggesting that pirinergic receptors of the P(2Y) class could be involved in this signalling pathway.     

Proactive interference, retroactive interference--what about self-interference? A new interpretation of the recency-primacy shift

The recency-primacy shift (RPS) indicates that memory for early list items improves and memory for later items becomes worse as the retention interval between study and test increases. In this contribution, this puzzling experimental finding--memory improving with time--is found to be consistent with a model in which recognition is temporarily interfered with by its own storage process (self-interference). I show that this interpretation can qualitatively better account for the RPS experimental data than can the dimensional distinctiveness model, the only other outstanding explanation of the RPS. Two experimental predictions separate the 2 models: The dimensional distinctiveness model predicts no RPS for 2-item lists, in contrast to self-interference, and as the overall timescale is changed, the dimensional distinctiveness model predicts no difference in the RPS whereas self-interference predicts significant changes.     

Potent inhibitory activity of chimeric oligonucleotides targeting two different sites of human telomerase

Suppression of telomerase activity in tumor cells has been considered as a new anticancer strategy. Here, we present chimeric oligonucleotides (chimeric ODNs) as a new type of telomerase inhibitor that contains differently modified oligomers to address two different sites of telomerase: the RNA template and a suggested protein motif. We have shown previously that phosphorothioate-modified oligonucleotides (PS ODNs) interact in a length-dependent rather than in a sequence-dependent manner, presumably with the protein part of the primer-binding site of telomerase, causing strong inhibition of telomerase. In the present study, we demonstrate that extensions of these PS ODNs at their 3'-ends with an antisense oligomer partial sequence covering 11 bases of the RNA template cause significantly increased inhibitory activity, with IC(50) values between 0.60 and 0.95 nM in a Telomeric Repeat Amplification Protocol (TRAP) assay based on U-87 cell lysates. The enhanced inhibitory activity is observed regardless of whether the antisense part is modified (phosphodiester, PO; 2'-O-methylribosyl, 2'-OMe/PO; phosphoramidate, PAM). However, inside intact U-87 cells, these modifications of the antisense part proved to be essential for efficient telomerase inhibition 20 hours after transfection. In particular, the chimeric ODNs containing PAM or 2'-OMe/PO modifications, when complexed with lipofectin, were most efficient telomerase inhibitors (ID(50) = 0.04 and 0.06 microM, respectively). In conclusion, ODNs of this new type emerged as powerful inhibitors of human telomerase and are, therefore, promising candidates for further investigations of the anticancer strategy of telomerase inhibition.