Resource partitioning in a guild of aphid species associated with creeping thistle Cirsium arvense

Four aphid species (Aphis fabae cirsiiacanthoidis Scop., Brachycaudus cardui (L.), Capitophorus carduinus Walker and Uroleucon cirsii (L.)) feed on the creeping thistle Cirsium arvense. They utilize different parts of their host plant and at different times. A wide niche is typical of C. carduinus and U. cirsii, whereas A. f. crisiiacanthoidis and B. cardui, show narrower but overlapping niches. Morphological features such as stylet length and body size as well as colony size and density are associated with the choice of feeding site. C. carduinus, the smallest species with the shortest stylets was able to use leaf veins and lamina, while the other species mainly used the stem and peduncles. Within this group, A. f. cirsiiacanthoidis and B. cardui are restricted to the upper part of the stem because of their short stylets, but adult U. cirsii, the species with the longest stylets, can also feed at the base of the stem.

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Räumliche und zeitliche ressourcenaufteilung in der blattlausgilde an der ackerkratzdistel cirsium arvense

Zusammenfassung An der Ackerkratzdistel leben vier Blattlausarten (Aphis fabae cirsiiacanthoidis Scop., Brachycaudus cardui (L.), Capitophorus carduinus Walker und Uroleucon cirsii (L.)), die im Verlauf der Vegetationsperiode verschiedene Strukturen ihrer Wirtspflanze nutzen. Eine breite Nische ist für U. cirsii und C. carduinus typisch, während A. f. cirsiiacanthoidis und B. cardui engere Nischen besitzen, die sich nahezu überlappen. Die Nahrungsplatzwahl wird sowohl durch morphologische Parameter wie Stilettlänge und Körpergewicht als auch durch Koloniegröe und Dispersion innerhalb der Kolonie beeinflut. Die kleinste Art, C. carduinus, die auch das kürzeste Stilett besitzt, ist in der Lage, an Blattadern und auf der Blattspreite zu saugen. Die anderen Arten bevorzugen Stengel, Seitenstengel und Blütenstiele. Innerhalb dieser Gruppe können A. f. cirsiiacanthoidis und C. carduinus wegen ihrer kürzeren Stilette nur am oberen Teil des Stengels saugen, während adulte U. cirsii aufgrund ihrer längeren Stilette auch an der Stengelbasis leben können.

     

Schwermetalle in Organen und Federn von Graureihern (Ardea cinerea) und Kormoranen (Phalacrocorax carbo)

Zusammenfassung Mittels der Atomabsorptionsspektroskopie wurden Lebern, Nieren und Federn von Graureihern und von diesjährigen Kormoranen auf Cadmium und Blei untersucht.Cadmium war in Geweben der Kormorane höher konzentriert als in gleichaltrigen Graureihern (Leber 0,063 bzw. 0,039, Niere 0,113 bzw. 0.104 mg/kg Frischmasse; Federn 0,077 bzw. 0,025 mg/kg Trockenmasse). Dies könnte auf unterschiedliche Nahrung oder unterschiedliche physiologische Situation der Vögel zurückzuführen sein. Als Maximum wurden in der Niere eines Kormorans 0,375 mg/kg gemessen. Bei den Graureihern konnte in Lebern und Nieren eine Altersakkumulation erkannt werden. Blei war in den Geweben beider Arten unterschiedlich hoch konzentriert. Kormorane enthielten in Lebern 0,124 und in Nieren 0,147 mg/kg Frischmasse sowie in Federn 0,442 mg/kg Trockenmasse, Graureiher 0,110, 0,157 bzw. 0,739 mg/kg. Die höchsten Konzentrationen wurden in Federn gemessen und betrugen bei einem Graureiher 4,525 mg/kg. Eine Altersakkumulation konnte bei Graureihern in Lebern nachgewiesen werden. Zusammenhänge zwischen Feder- und Organbelastungen wurden nur bei diesjährigen Graureiher- erkannt: Federcadmium und Lebercadmium korrelierten positiv miteinander.

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Heavy metals in tissue and feathers of Grey Herons (Ardea cinerea) and Cormorants (Phalacrocorax carbo sinensis)

Summary The livers, kidneys and feathers of 40 Grey Herons and 20 Cormorants were investigated by AAS to determine the extent of contamination with cadmium and lead. The birds had been shot in autumn 1979–1986 in Schleswig-Holstein. All results are given in mg/kg (ppm) wet mass (liver, kidney) or dry weight (feather). On the average, the contamination by cadmium in the livers (0.063), kidneys (0.113) and feathers (0.077) was higher in Cormorants than in Grey Herons (0.039, 0.104 and 0.025). These differences may be the result of different food or physiology. The livers and kidneys of young Grey Herons contained less cadmium than the tissue of older birds. The feathers of male Grey Herons contained more cadmium than feathers of females do. This was also the case in kidneys of male Cormorants as compared to the females. Cadmium values in livers and kidneys were positive correlated. No general tendency was detectable in regards to lead contamination. The results concerning Cormorants were 0.124 (liver), 0.147 (kidney), 0.442 (feather) and concerning Grey Herons 0.110, 0.157 and 0.739. The livers of old Grey Herons were more highly contaminated by lead than livers of young ones. The feathers of male Herons contained two times more lead than the feathers of females do.In general, a concentration of heavy metals in feathers does not indicate a contamination of livers or kidneys. A correlation between the values in feathers and tissue was evident only in one case, where a positive correlation was found between feather- and liver cadmium in young male Grey Herons.

     

Core substructure in Mastigocladus laminosus phycobilisomes

A native high molecular complex (M_r 850000) containing about 50% of the allphycocyanin of the phycobilisome but lacking allophycocyanin B was separated from isolated phycobilisomes by gel electrophoresis. It was designated AP_CM since the large linker polypeptide L_CM was exclusively localized in this complex. The complex exhibited a ?196°C fluorescence emission maximum at 673 nm (671 nm at 25°C). In addition, a core complex (designated AP_C, M_r≥1000000) consisting of both AP_CM and AP 680 was isolated by combined gel filtration and linear gradient centrifugation. At 25°C this complex showed dual emission peaks at 670 and 680 nm demonstrating functional independence of the terminal emitters. A complex similar to AP_CM can be isolated from phycobilisomes of Anabaena variabilis. This is evidence that AP_CM is the constitutive center of the tricylindrical core of hemidiscoidal cyanobacterial phycobilisomes. Two models summarizing the structural and functional consequences of the results are presented in the discussion.     

Heterozygous expression of X-linked chondrodysplasia punctata

Summary Two females showing partial expression of X-linked chondrodysplasia punctata were identified in a family. Bone dysplasia was caused by an aberrant X chromosome that had an inverse duplication of the segment Xp21.2–Xp22.2 and a deletion of Xp22.3-Xpter. To characterise the aberrant X chromosome, dosage blots were performed on genomic DNA from a carrier using a number of X-linked probes. Anonymous sequences from Xp21.2–Xp22.2 to which probes D2, 99.61, C7, pERT87-15, and 754 bind were duplicated on the aberrant X chromosome. The proposita was heterozygous for all these markers. Dosage blots also showed that the loci for steroid sulfatase and the cell surface antigen 12E7 (MIC2) were deleted as expected from the cytogenetic results. Mouse human cell hybrids were constructed that retained the normal X in the active state. Analysis of these hybrid clones for the markers from Xp21.2–Xp22.2 revealed that all the alleles of the informative markers, present in a single dosage in the genomic DNA, were carried on the normal X chromosome of the proposita. The duplicated X chromosome therefore had two identical alleles, indicating that the aberration resulted from an intrachromosomal rearrangement.     

The phylogenic position of Peptococcus niger based on 16S rRNA sequence studies

A 1330 base-pair fragment of a 16S rRNA gene has been amplified, cloned and sequenced. Comparison to other 16S rRNA sequences of eubacteria showed that P. niger represents a deep branch within the subdivision "Gram-positive with Gram-negative cell walls". It is not related to peptostreptococci, representatives of this genus studied so far are more closely related to clostridia.     

The endogenous lectins of the chick blastoderm are present in association with an apolipoprotein in distinct organelles and in the extracellular matrix

Summary Affinity purified preparations of the galactose-binding lectin from gastrulating chick blastoderms consist of three main polypeptides. Two of these have been identified as the 14 kD and 16 kD galactose-binding lectins. A third one migrates in SDS-PAGE gels with a relative molecular weight of 6,500±500 and has been identified as an apolipoprotein (Apo) of plasma very low density lipoproteins, Apo-VLDL-II. We have studied the localization of these polypeptides using immunofluorescence and ultrastructural immunocytochemistry with peroxidase and protein-A gold. The 14 kD lectin occurs in the intracellular yolk where it is mainly present within the electron lucent component. The 16 kD is also present in the intracellular yolk platelets, but tends to predominate in the electron-dense component. In addition, the 16 kD lectin is also present in pleiomorphic yolk-associated organelles and in the extracellular matrix. Apo-VLDL-II is also localized in the electron-lucent component of the yolk platelet and in the extracellular matrix. Our results suggest that the lectin(s) are associated with Apo-VLDL-II in the yolk platelet, and may subsequently become externalized.     

Artificial dimers of native actin: Preparation and properties in biological functions

With the aid of tartryl-bis--aminocaprylazide artificial dimers were produced from F actin from rabbit striated muscle. These derivatives will not polymerize by themselves but are able to copolymerize fully with native G actin. By modification of a single side chain per dimer, this copolymerization was completely inhibited. The dimers are able to activate subfragment I ATPase of myosin and bind to DNase I with inactivation of the enzyme in the same manner as native G actin. Within the dimer, one ADP is immobilized and will exchange against ATP extremely slowly. The dimers do not bind to the mushroom toxin phalloidin.     

Plasmids in toxic and nontoxic strains of the cyanobacteriumMicrocystis aeruginosa

The plasmid content and toxicity of nine different strains ofMicrocystis aeruginosa have been analyzed. The two toxic strains of the HUB Culture Collection were found to carry each two plasmids, pMA1 and pMA2, of 2.9 kb and 8.5 kb, respectively. In strains PCC 7813 and PCC 7820, also toxic, two different plasmids of 2.6 kb and 16 kb were detected. Hybridization experiments showed that there exists no sequence homology between the pMA plasmids and the plasmids found in the PCC strains; but the pMA plasmids hybridized to chromosomal DNA of the toxic strains PCC 7820, PCC 7813, HUB 063, and the nontoxic strain HUB 5-3. In nontoxic strains no or at most one plasmid of unstable occurrence could be detected. Only one of the toxic strains investigated, SAG 14.85 (NRC-1), contained no plasmid.