The effect of glucosinolates on responses of young Phyllotreta nemorum larvae to non-host plants

All recorded host plants of Phyllotreta nemorum L. (Coleoptera: Chrysomelidae) contain glucosinolates and belong to the plant families Brassicaceae (Cruciferae), Resedaceae and Capparaceae. The acceptability of 56 plant species from 28 other plant families (non-hosts) for young larvae has been studied in the laboratory. None of these species were fully acceptable for initiations of leaf mines when intact untreated leaves were presented, and only one species, Malva silvestris L. (Malvaceae), was partially acceptable. The acceptability of some species increased when leaf discs were presented instead of intact leaves; but the highest percentages of mine initiations occurred in leaf discs treated with the glucosinolate, sinigrin. A stimulatory effect of sinigrin could be demonstrated in experiments with 7 plant species: Papaver dubium L., Papaver rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. and Lactuca sativa L. The majority of species remained unacceptable even after treatment with glucosinolates.The main causes for these differences between plant species are supposed to be differences in contents of deterrents and/or other stimulants for mine initiation. These possibilities are discussed in relation to the content of allelochemicals in acceptable plants and the position of these plants in botanical classifications.

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Zusammenfassung Phyllotreta nemorum L. ist ein oligophager Erdfloh, der an Cruciferen und anderen Glukosinolat-haltigen Pflanzenarten gebunden ist. Die Imagines fressen Löcher in die Blätter und die Weibchen legen ihre Eier in den Boden. Die Larven sind Blattminierer. Nach dem Schlüpfen im Boden klettern sie an die Pflanzen hoch, und die Einbohrung und der Anfang der Minierung erfolgt in eines der unteren Blätter der Wirtspflanze.Die Wirkung von Glukosinolaten auf die Einbohrung von Junglarven in Pflanzenarten, die keine natürliche Inhalt von Glukosinolaten haben, ist in Laborexperimenten untersucht worden. 56 Pflanzenarten aus 28 Familien wurden präsentiert teils als unbehandelte Blätter und teils als Glukosinolatbehandelte Blattscheiben. Unbehandelte Blätter von nicht-Glukosinolathaltigen Arten waren immer unbefriedigend für die Larven. Nur in eine Art, Malva silvestris L. war die Frequenz der Einbohrung ein bisschen höher als 10%. Eine signifikante Erhöherung der Anzahl eingebohrten Larven nach der Sinigrin-behandlung erfolgte in 7 Pflanzenarten: Papaver dubium L., P. rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. und Lactuca sativa L. Doch blieben die meisten Pflanzenarten (84%) auch nach der Sinigrin-Behandlung unbesiedelt.Pflanzenarten, die nach der Sinigrin-Behandlung nicht besiedelt werden enthalten vielleicht frasshemmende Stoffe, oder ihnen fehlen noch weitere Frass-stimulierende Stoffe. Diese Möglichkeiten werden diskutiert in Zusammenhang mit den Inhalt von Allelochemikalien in besiedelten Pflanzenarten und mit ihrer taxonomischer Position.

     

Palindromy and the Location of Deletion Endpoints in Escherichia Coli

The contributions of direct and inverted repeats to deletion formation were studied by characterizing Ampr revertants of plasmids with a series of insertion mutations at a specific site in the pBR322 ampicillin resistance (amp) gene. The inserts at this site are palindromic, variable in length, and bracketed by 9- or 10-bp direct repeats of amp sequence. There is an additional direct repeat composed of 4 bp within the insert and 4 bp of adjoining amp sequence. DNA sequencing and colony hybridization of Ampr revertants showed that they contained either the parental amp sequence, implying deletion endpoints in the flanking 9- or 10-bp repeats, or a specific 1-bp substitution, implying endpoints in the 4-bp repeats. Although generally direct repeats seem to be used as deletion endpoints with a frequency proportional to their lengths, we found that with uninterrupted palindromes longer than 32 bp, the majority of deletions ended in the 4 bp, not the 9- or 10-bp repeats. This preferential use of the shorter direct repeats associated with palindromes is interpreted according to a DNA synthesis-error model in which hairpin structures formed by intrastrand pairing foster the slippage of nascent strands during DNA synthesis.     

Risk of nonocular cancer in first-degree relatives of retinoblastoma patients

Summary The increased risk of nonocular cancer seen consistently in studies of survivors of retinoblastoma may be caused in part by the presence of a retinoblastoma gene that also predisposes to other cancers. It has been claimed that this gene also increases the risk for cancer among unaffected relatives of genetic retinoblastoma probands. We report here a population-based study of the risk of nonocular cancer in parents and siblings of persons notified to the Danish Cancer Registry with retinoblastoma during 1943–84. No excess was observed among first degree relatives of 61 genetic retinoblastoma probands, whereas a slight (10%) excess was seen among the parents of 115 nongenetic probands. The latter was the result of significant excesses of malignant melanoma (4 observed, 0.4 expected), multiple myeloma (2 observed, 0.2 expected) and osteogenic sarcoma (1 observed, 0.03 expected). The observed risk pattern cannot be explained by the presence of the retinoblastoma gene.     

Linkage between the variegate porphyria (VP) and the alpha-1-antitrypsin (PI) genes on human chromosome 14

Summary We describe a new rare allele for esterase D (EsD) occurring in a Portuguese family with retinoblastoma in two generations.     

The alpha 5 gene product assembles with multiple acetylcholine receptor subunits to form distinctive receptor subtypes in brain.

The acetylcholine receptor (AChR) alpha 5 gene has been classified as a member of the AChR gene family based on sequence homology. Expression studies, however, have yet to identify a function for the alpha 5 gene product or even to demonstrate an interaction with known AChR subunits. We report here that the alpha 5 gene product is identical to the 49 kd protein previously found on immunoblots of AChRs purified from brain and ciliary ganglia. In brain the alpha 5 gene product is present both in alpha 3- and in alpha 4-based receptor subtypes, while in the ganglion it is found in an alpha 3-based receptor subtype concentrated in postsynaptic membrane. Immunoprecipitation experiments with subunit-specific monoclonal antibodies indicate that some native AChRs are likely to have at least three kinds of subunits, with two being of the alpha type. These findings support new views about the construction of AChRs in neurons.     

Large-scale preparation and reconstitution of apo-flavoproteins with special reference to butyryl-CoA dehydrogenase from Megasphaera elsdenii. Hydrophobic-interaction chromatography

A new method is described for the large-scale reversible dissociation of flavoproteins into apoprotein and prosthetic group using hydrophobic-interaction chromatography. Lipoamide dehydrogenase from Azotobacter vinelandii and butyryl-CoA dehydrogenase from Megasphaera elsdenii are selected to demonstrate the usefulness of the method. In contrast to conventional methods, homogeneous preparations of apoproteins in high yields are obtained. The apoproteins show high reconstitutability. The holoenzymes are bound to phenyl-Sepharose CL-4B at neutral pH in the presence of ammonium sulfate. FAD is subsequently removed at pH 3.5-4.0 by addition of high concentrations of KBr. Large amounts of apoenzymes (200-500 mg), showing negligible residual activity, are eluted at neutral pH in the presence of 50% ethylene glycol. The holoenzyme of lipoamide dehydrogenase can be reconstituted while the apoprotein is still bound to the column or the apoenzyme can be isolated in the free state. In both cases the yield and degree of reconstitution of holoenzyme is more than 90% of starting material. Apo-lipoamide-dehydrogenase exists mainly as a monomer in solution and reassociates to the native dimeric structure in the presence of FAD. The apoenzyme is stable for a long period of time when kept in 50% ethylene glycol at -18 degrees C. Steady-state fluorescence-polarization measurements of protein-bound FAD indicate that reconstituted lipoamide dehydrogenase possesses a high stability which is governed by the low dissociation rate constant of the apoenzyme-FAD complex. The holoenzyme of butyryl-CoA dehydrogenase cannot be reconstituted when the apoenzyme is bound to the column. However, stable apoprotein can be isolated in the free state yielding 50-80% of starting material, depending on the immobilization conditions. The coenzyme A ligand present in native holoenzyme is removed during apoprotein preparation. The apoenzyme is relatively stable when kept in 50% ethylene glycol at -18 degrees C. From kinetic and gel filtration experiments it is concluded that the reconstitution reaction of butyryl-CoA dehydrogenase is governed by both the pH-dependent hydrodynamic properties of apoenzyme and the pH-dependent stability of reconstituted enzyme. At pH 7, the apoenzyme is in equilibrium between dimeric and tetrameric forms and reassociates to a native-like tetrameric structure in the presence of FAD. The stability of reconstituted enzyme is strongly influenced by the presence of CoA ligands as shown by fluorescence-polarization measurements. The degree of reconstitution of butyryl-CoA dehydrogenase is more than 80% of the original specific activity under certain conditions.(ABSTRACT TRUNCATED AT 400 WORDS)