Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence

Summary Eight representative recombinant background clones of λEMBL3 were analysed usingKpnI,BamHI,SalI,EcoRI andHindIII digestion. We found that λEMBL3 carries its own left arm in theBamHI cloning site. In this way, recombinant molecules were found to be generated which can grow onEscherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restoredBamHI site at thecos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated,BamHI cloning produces a large palindromic sequence consisting of two polylinkers. ThisBamHI site was incompletely cleaved in all cases analysed. We assume that a part of the λ DNA molecule in this region shows a cruciform structure prohibiting recognition or cleavage of this site by restriction endonucleaseBamHI.     

A mutant rat major histocompatibility haplotype showing a large deletion of class I sequences

The LEW.1LM1 inbred rat strain, which has been derived from a (LEW×LEW.1W) F₂ hybrid, carries a major histocompatibility (RT1) haplotype which is distinct from that of the LEW strain (RT1 ¹) in that certainRT1.C region-determined class I antigens are not expressed. Here we show that this phenotypic defect is due to genomic deletion of about 100 kb of theRT1.C region. Certain deleted DNA fragments have been cloned from the wild-type DNA into the EMBL4 vector. Five clones have been characterized and are shown to possess different restriction maps and to each carry a single stretch of class I cross-hybridizing sequences. Probes derived from the non-class I coding part of two clones detect fragments which are present in the wild-type but absent from thelm1 mutant. The type of deletion described here in the rat is discussed in the context ofH-2D/Q deletions in the mouse.     

Allelic variation in HLA-B and HLA-C sequences and the evolution of the HLA-B alleles

Several new HLA-B (B8, B51, Bw62)- and HLA-C (Cw6, Cw7)-specific genes were isolated either as genomic cosmid or cDNA clones to study the diversity of HLA antigens. The allele specificities were identified by sequence analysis in comparison with published HLA-B and -C sequences, by transfection experiments, and Southern and northern blot analysis using oligonucleotide probes. Comparison of the classical HLA-A, -B, and -C sequences reveals that allele-specific substitutions seem to be rare events. HLA-B51 codes only for one allelespecific residue: arginine at position 81 located on the 1 helix, pointing toward the antigen binding site. HLA-B8 contains an acidic substitution in amino acid position 9 on the first central sheet which might affect antigen binding capacity, perhaps in combination with the rare replacement at position 67 (F) on the ul helix. HLA-B8 shows greatest homology to HLA-Bw42, -Bw41, -B7, and-Bw60 antigens, all of which lack the conserved restriction sites Pst I at position 180 and Sac I at position 131. Both sites associated with amino acid replacements seem to be genetic markers of an evolutionary split of the HLA-B alleles, which is also observed in the leader sequences. HLA-Cw7 shows 98% sequence identity to the JY328 gene. In general, the HLA-C alleles display lower levels of variability in the highly polymorphic regions of the 1 and 2 domains, and have more distinct patterns of locus-specific residues in the transmembrane and cytoplasmic domains. Thus we propose a more recent origin for the HLA-C locus.     

Effects of nucleotides and divalent cations on phospholipase activity in Saccharomyces cerevisiae

Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.     

Expression of acetylcholinesterase during visual system development in Drosophila

As in other insects acetylcholine (ACh) and acetylcholinesterase (AChE) function in synaptic transmission in the central nervous system of Drosophila. Studies on flies mutant for AChE indicate that in addition to its synaptic function of inactivating acetylcholine, this neural enzyme is required for normal development of the nervous system (J.C. Hall, S.N. Alahiotis, D.A. Strumpf, and K. White, 1980, Genetics 96, 939-965; R.J. Greenspan, J.A. Finn, and J.C. Hall, 1980, J. Comp. Neurol. 189, 741-774). In order to understand what role AChE may play in neural development, it is necessary to know, in detail, where and when the enzyme appears. The use of monoclonal antibodies to localize AChE in the developing visual system of wild type Drosophila has yielded the novel observation that AChE appears in photoreceptor (retinula) cells 4-6 hr after they differentiate and 3 to 4 days before they are functional. Three days later the staining in the cell body of these cells is reduced. Because retinula cells have no functional connections at the time when AChE is first detected, AChE can not be performing its standard synaptic function. Subsequent to the reduction of AChE in the retinula cells, midway through the pupal stage, the enzyme accumulates rapidly in the neuropils of the optic lobes of the brain. Thus, there is a biphasic accumulation of AChE in the developing visual system with the enzyme initially being expressed in the retinula cells and accumulating later in the optic lobes.     

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.

     

Genetic studies on nucleolus organizer regions (NORs) in cattle

Experimentally produced monozygotic twins, natural opposite sex blood chimeras (freemartins), and several pedigrees were used to evaluate the genetic influences on the nucleolus organizer region (NOR) patterns in cattle. In monozygotic twins, the NOR patterns of both twins are extremely similar. In chimeras, NOR patterns of genetically identical, peripheral blood lymphocytes (PBL) from the two partners resemble each other. In contrast, genetically different PBL (sib organ) differ significantly in the same environment. A high heritability of the individual NOR patterns is also demonstrated in our 23 pedigrees. In conclusion, our data demonstrate that variation in NOR expression is predominantly due to genetic factors.     

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.