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Strobilurins A and X, isolated from Mucidula venosolamellata culture extracts, demonstrated potent inhibition of human melanoma G-361 cell proliferation. Strobilurin X exhibited milder inhibitory effects on human fibroblast cells (NB1RGB) compared to strobilurin A. Additional strobilurin-related compounds were isolated from the other mushroom species. Oudemansins A and B displayed weaker activities on G-361 cells than strobilurins A and B, respectively, emphasizing the importance of a conjugated double-bond structure. Among isolated compounds, strobilurin G showed the lowest IC50 value for G-361 cells. Additional strobilurins bearing various substituents on the benzene ring were synthesized. Synthetic intermediates lacking the methyl β-methoxyacrylate group and a strobilurin analogue bearing modified β-methoxyacrylate moiety showed almost no inhibitory activity against G-361 cells. The introduction of long or bulky substituents at the 4′ position of the benzene ring of strobilurins enhanced the activity and selectivity, suggesting differential recognition of the benzene ring by G-361 and NB1RGB cells. [ABSTRACT FROM AUTHOR]

We characterized ATP-induced changes in intracellular [Ca.sup.2+] concentration ([[[Ca.sup.2+]].sub.i]) and membrane current in cultured rat myenteric neurons using ratiometric [Ca.sup.2+] imaging with fura-2 and the whole cell patch-clamp technique, respectively. Neuronal cells were functionally identified by [[[Ca.sup.2+]].sub.i] responses to high [K.sup.+] and nicotine, which occurred only in cells positive for neuron-specific protein gene product 9.5 immunoreactivity. ATP evoked a dose-dependent increase of [[[Ca.sup.2+]].sub.i] that was greatly decreased by the removal of extracellular [Ca.sup.2+] concentration ([[[Ca.sup.2+]].sub.o]). The amplitude of the [[[Ca.sup.2+]].sub.i] response to ATP was reduced by half in the presence of voltage-dependent [Ca.sup.2+] channel blockers. In [[[Ca.sup.2+]].sub.o]-free solution, ATP produced a small transient rise in [[Ca.sup.2+].sub.i] similar to that induced by P2Y agonists. At -60 mV, ATP evoked a slowly inactivating inward current that was suppressed by the removal of extracellular [Na.sup.+] concentration. The current-voltage relation for ATP showed an inward rectification with the reversal potential of about 0 mV. The apparent rank order of potency for the purinoceptor agonist-induced increases of [[Ca.sup.2+].sub.i] was ATP [greater than or equal to] adenosine 5'-O-3-triphosphate [greater than or equal to] CTP [greater or equal to] 2-methylthio-ATP > benzoylbenzoyl-ATP. A similar potency order was obtained with current responses to these agonists. P2 antagonists inhibited inward currents induced by ATP. [Ca.sup.2+] and [Mg.sup.2+] suppressed the ATP-induced current, and [Zn.sup.2+], [Cu.sup.2+], and protons potentiated it. RT-PCR and immunocytochemical studies showed the expression of P2[X.sub.2] receptors in cultured rat myenteric neurons. These results suggest that ATP mainly activates ionotropic P2[X.sub.2] receptors, resulting in a [[[Ca.sup.2+].sub.i] increase dependent on [[[Ca.sup.2+]].sub.o] in rat myenteric neurons. A small part of the ATP-induced [[[Ca.sup.2+]].sub.i] increase may be also mediated via a P2Y receptor-related mechanism. enteric neuron; fura-2; patch clamp; purinoceptor

The fortimicin-A (FTM-A) resistance genes (fmr) in five FTM-producing actinomycetes were isolated and characterized and compared to the fmr genes of other actinomycetes. The results showed that the different fmr genes could be classified into two types based on the resistance profiles to aminoglycoside antibiotics. DNA hybridization analysis confirmed this classification based on resistance profiles.

The neuraminidase gene (nedA) from Micromonospora viridifaciens was cloned and sequenced. The gene was cloned by using pIJ702 as a vector and expressed constitutively in the heterologous host Streptomyces lividans. An open reading frame (ORF) of 1,941 bp encoded a 68-kDa protein. Thededuced amino acid sequence had five Asp boxes found in other bacterial neuraminidases. Another ORF, termed nedR, was found in the region upstream of nedA. The deduced amino acid sequence showed some similarity with the Tn3 repressor.