Prediction of heavy-metal concentrations in mature plants by chemical analysis of seedlings

Five plant species were cultivated on a soil from the Neckar alluvial fan near Heidelberg (FRG) polluted by the emissions of a cement plant. Thallium, cadmium and lead concentrations in seedlings and mature plants were determined by atomic absorption analysis. AdditionallyBrassica napus L.napus was grown on soils containing 5 different concentrations of heavy metals, achieved by mixing two similar soils, from the same area but with different metal concentrations. Thallium and cadmium were shown to be taken up by roots whilst lead which was also absorbed, was deposited mainly on the plant surface. However during cultivation in the winter months, a remarkable deposit of lead via the roots was found. Thallium in the soil from a anthrorogen source was more available to plants than thallium of geological origin. During the lifetime of a plant concentrations of thallium and cadmium were always highest in the seedling. The decrease in metal concentration with maturity depended on the plant species and the element, but was not a function of the metal concentration in the soil.     

Induction and floral determination in the terminal bud of Nicotiana tabacum L. cv. Maryland Mammoth,a short-day plant

Floral determination in the terminal bud of the short-day plant Nicotiana tabacum cv. Maryland Mammoth has been investigated. Plants grown continuously in short days flowered after producing 31.4±1.6 (SD) nodes while plants grown continuously in long days did not flower and produced 172.5±9.5 nodes after one year. At various ages, expressed as number of leaves that were at least 1.0 cm in length above the most basal 10-cm leaf, one of three treatments was performed on plants grown from seed in short days: 1) whole plants were shifted from short days to long days, 2) the terminal bud was removed and then rooted and grown in long days, and 3) the terminal bud was removed and then rooted and grown in short days. Whole plants flowered only when shifted from short days to long days at age 15 or later. Only rooted terminal buds from plants at age 15 or older produced plants that flowered when grown in long days. Only terminal buds from plants at age 15 or older that were rooted and grown in short days produced the same number of nodes as they would have produced in their original locations while buds from younger plants produced more nodes than they would have in their original locations. Thus, determination for floral development in the terminal bud, as assayed by rooting, is simultaneous with the commitment to flowering as assayed by shifting whole plants to non-inductive conditions.Abbreviations LD long day(s) - SD short day(s) - DN dayneutral     

Single potassium channels in membranes of isolated mesophyll barley vacuoles

Summary Voltage-dependent K channels could be identified in on-cell and excised patch-clamp records on membranes of isolated plant cell vacuoles. The current through a membrane patch is dominated by a channel population with a conductance of about 121 pS in symmetrical 250mm KCl solution. The single channel adopts at least two conducting levels the 121-pS state being most frequently observed. The channel shows outward rectification, representing a cation flux into the vacuoles. The rectification appears to be caused by a vanishing open probability and a short channel lifetime at hyperpolarizing voltages. A selectivity ratio of potassium over sodium of about 6 was derived as an estimate. Occasionally, an additional population of K channels with a single-channel conductance of approximately 18 pS is observed. This channel type exhibits outward rectification as well.     

Effect of Hirschmanniella caudacrena on the Submersed Aquatic Plants Ceratophyllum demersum and Hydrilla verticillata

In vitro pathogenicity tests demonstrated that Hirschmanniella caudacrena is pathogenic to Ceratophyllum demersum (coontail). Symptoms were chlorotic tissue, deformed stems, and, finally, death of the plant. Inoculum densities of 500 nematodes per 5-cm-long cutting in a test tube containing 50 ml of water resulted in death and decay of some of the cuttings within 8 weeks; 100 nematodes killed the plants in 12 weeks, and 50 and 25 nematodes killed them in 16 weeks. The lowest inoculum level of 10 nematodes did not seriously affect the plants at 16 weeks when the experiment was terminated. A second test conducted outdoors in glass jars containing 3 liters of water and two cuttings weighing a total of 15 g fresh weight showed damage, but results were not statistically significant. Hydrilla verticillata inoculated with H. caudacrena was not affected seriously.     

实夜蛾属二近缘种对寄主植物次生物质的反应:次生物质对幼虫生长和食物利用的影响

实夜蛾属(Heliothis)的棉铃虫(H. armigcra)和烟青虫(H. assulta)是近缘种,幼虫期取食多种相同的植物,其中含有不同的次生物质.本项工作是在人工饲料中分别加入0.5%的烟碱、番茄苷、棉子酚、丹宁酸等饲养早期六龄的幼虫,测定它们对生长和食物利用的影响.结果表明这些次生物质对两种幼虫有不同的作用:烟碱对棉铃虫没有明显影响,但对烟青虫的取食却有一定的刺激作用.丹宁酸、棉子酚、番茄苷可抑制两种幼虫的生长,而以番茄苷抑制烟青虫的生长最为显著.番茄苷主要通过抑制取食来影响幼虫的生长,而丹宁酸和棉子酚则具有降低消化率的作用.通过次生物质对这两种幼虫效应的比较可知,棉铃虫有较大的忍耐力.     

Revision of the plant geographical territories of Israel and Sinai

The phytogeographical territories of Israel and Sinai are revised using a large mass of species distribution data. With the help of chorotype frequencies for 25 km² individual squares in Israel, territories were defined on the basis of the first two most frequent chorotypes. The similarity of boundaries in the resulting phytogeographical map with a physiognomic map suggests that the latter may be used in preliminary stages of the preparation of plant geographical maps.     

Types I and IV collagenolytic and plasminogen activator activities in preovulatory ovarian follicles

During ovulation, enzymatic degradation of the extracellular matrix occurs within and around the graafian follicles. In this study, the activities of several different proteolytic enzymes were measured in the culture media of follicles taken from pregnant mare serum gonadotropin (PMSG)-primed immature rats. At 52 h after PMSG, the follicles were cultured for 2 to 15 h in media with or without human chorionic gonadotropin (hCG). Type I collagenase activity in hCG-stimulated follicles gradually increased within 6 h to 3.3-fold above that of the controls. Relatively pure populations of granulosa cells produced type I collagenase to a similar extent. Likewise, type IV collagenase increased 3.8-fold by 6 h after exposure of the follicles to hCG. In contrast, plasminogen activator activity increased by 3.9-fold at 2 h after hCG, but was negligible at 4, 6, and 15 h after incubation. These results suggest that plasminogen activator may activate both type I and type IV collagenase in hCG-stimulated ovulatory follicles.     

Egg-laying strategy under natural conditions of Leptopilina boulardi, a hymenopteran parasitoid of Drosophila spp

The hypothesis of optimal host species selection predicts that when a parasitoid has the choice between two host species, it will choose the species thay gives the best survival chances for its progeny. We confirmed this hypothesis by laboratory experiments with Leptopilina boulardi Barb. et al., a cynipid parasitoid which prefers Drosophila melanogaster Meigen (the host species most suitable for parasitoid survival) above D. simulans Sturt. As far as fitness parameters are concerned, the fertility of L. boulardi is higher with D. melanogaster; the egg laying can be spread out over a long period when this host is relatively scarce. This does not occur with D. simulans in which parasitic oviposition stops soon when this host is not abundant.Investigations of this foraging strategy were done under more complex natural conditions. We found that L. boulardi has a type III functional response with D. melanogaster only; furthermore, it seems that a switching effect may exist with this host. Parasitoid females appear to distribute their eggs more regularly on D. melanogaster, thus avoiding superparasitism. This seems to be independent of the relative frequency of this host. However, superparasitism of D. simulans did occur more frequently when this host was scarce.

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Stratégie de ponte de Leptopilina boulardi (hyménoptère parasite de drosophiles) dans les conditions naturelles

Résumé Le concept de réponse optimale d'un parasite vis-à-vis de l'hôte le plus favorable pour son développement demeure surtout théorique et n'a pu être vérifié que dans les conditions de laboratoire. Nous avons montré que Drosophila melanogaster s'avère être, par rapport à D. simulans, l'hôte le plus favorable pour le développement du cynipide parasite Leptopilina boulardi. Une étude sur le terrain a démontré que ce parasite présente une réponse fonctionnelle densité dépendante vis-à-vis de D. melanogaster et non vis-à-vis de D. simulans, avec un effet de bascule. D'autre part, il s'avère que ce parasite exploite beaucoup mieux son hôte, en évitant le superparasitisme, ceci étant démontré au laboratoire et dans la nature. Enfin, il apparaît qu'il est capable d'allonger sa période de ponte lorsque cet hôte est rare, ce qui ne se produit pas avec D. simulans.

     

Feeding responses to solanaceous allelochemicals by larvae of the tobacco hornworm, Manduca sexta

Feeding responses of the oligophagous tobacco hornworm to allelochemicals prevalent in their host plants were determined in food choice-tests using filter paper discs laced with a test solution or water (control). Six solanaceous alkaloids, tomatine, tomatidine, solanine, solanocapsine, atropine and nicotine, were tested and only tomatine and solanocapsine were found to influence preference behavior. Solanocapsine (5 mM) deters feeding whereas tomatine (1 mM) stimulates feeding slightly. No synergistic effect of either tomatine or tomatidine with sucrose was found.The responses to tomatine are affected by previous feeding experience. Tomatine slightly stimulates feeding in larvae reared on tomato (Lycopersicon esculentum), but slightly deters feeding in larvae reared on Jerusalem cherry (Solanum pseudocapsicum). Such induced preference is absent for the other alkaloids tested, which indicates that these alkaloids do not by themselves induce preferences for the plants containing them.The non-alkaloid allelochemicals, chlorogenic acid, rutin, and 2-tridecanone also influenced food choice behavior. Chlorogenic acid is slightly stimulatory at its natural concentration (1mM), but strongly deterrent at higher concentrations. Rutin stimulates feeding in a concentration-dependent manner. Its activity must be due to the glycosylated structure, because both the aglycone (quercetin) and the sugar moiety (rutinose) are neutral. Removal of the glucose part of rutin, as in quercitrin, results in feeding deterrent activity. 2-Tridecanone is neutral at its concentration in cultivated tomato (1 mM), but strongly deterrent and toxic at higher concentrations. Preference behavior is not affected by solanesol, GABA, and a mixture of host plant compounds stimulatory for anothe solanaceous-specific feeder, the Colorado potato beetle (Leptinotarsa decemlineata).We conclude that the prevalent solanaceous alkaloids and other allelochemicals tested do not play important roles in food selection of the tobacco hornworm, although some may make small contributions.

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Résumé Des experiences de choix de chenilles oligophages de M. sexta ont été réalisees avec des disques de papier filtre imbiles d'eau ou de solutions des substances allélochimiques dominantes dans les plantes consommées. Sur les six alcaloïdes de solanées examinés: tomatine, tomatidine, solanine, solanocapsine, atropine et nicotine, seuls la tomatine et la solanocapsine ont influé sur le choix; la solanocapsine (5 mM) empêche la prise de nourriture, tandis que la tomatine (1 mM) la stimule légèrement. Aucun effet synergique de la tomatine ou de la tomatidine n'a été observé en présence de sucrose.La réponse à la tomatine est modifiée par la prise de nourriture antérieure. Elle stimule légèrement l'alimentation de chenilles élevées sur tomates (Lycopersicon esculentum), mais dissuade légèrement les chenilles élevées sur Solanum pseudocapsicum. II n'y a pas d'action induite semblable avec les autres alcalïdes examinés, ce qui indique que ces alcaloïdes ne peuvent pas induire par eux-mêmes de préférences pour les plantes qui les contiennent.Des substances allélochimiques non-alcaloïdes: acide chlorogénique, rutine, et 2-tridécanone, influent aussi sur le comportement de choix alimentaire. L'acide chlorogénique est légèrement stimulant à sa concentration naturelle (1 mM), mais fortement dissuasif aux concentrations supérieures. La rutine stimule la prise de nourriture en fonction de sa concentration. Son activité doit être due à sa structure glucosylate, puisqu'aussi bien l'aglycone (quercitine) que la moiteé sucrée (rutinose) sont neutres. La suppression de la partie glucose de la rutine, comme dans le cas de la quercitine, a un effet dissuasif. A sa concentration dans la tomate cultivée (1 mM), le 2-tridécanone est neutre, mais il est fortement dissuasif et toxique à des concentrations supérieures.Le comportement de choix n'est pas modifié par le solanésol, le GABA, et par un mélange de composés végétaux stimulant un consommateur spécifique de solanées, comme le doryphore (Leptinotarsa decemlineata).Nous pouvons conclure que les principaux alcaloïdes et autres substances allélochimiques des solanées que nous avons examinés n'interviennent pas d'une façon importante, mais peuvent avoir une influence secondaire, dans les choix alimentaires de Manduca sexta.

     

Stereoselective total synthesis of ceramide Di-, Tri- and tetrahexosides of wheat flour

The first total synthesis of glycosphingolipids isolated from wheat flour has been achieved in a regio- and stereo-controlled manner.Abbreviations THF tetrahydrofuran - DMF dimethylformamide Part 53 in the series Synthetic Studies on Cell Surface Glycans