Die Beinmuskulatur und ihre Innervation bei der VogelspinneDugesiella hentzi (Ch.) (Araneae,Aviculariidae)

Zusammenfassung Gestützt auf präparative Untersuchungen und histologische Serienschnitte werden Zahl, Lage, Funktion und nervöse Versorgung aller Muskeln in den Laufbeinen der erwachsenen VogelspinneDugesiella hentzi (Ch.) beschrieben. In den acht Laufbeinen können gleichermaßen jeweils dreißig Muskeln unterschieden werden.Bis auf eine Ausnahme (M. 30) erfolgt die Innervation sämtlicher Beinmuskeln durch den Beinnerv B, wobei die Versorgung durch mehrere (bis zu 6) Nervenäste pro Muskel die Regel ist. Jeder Ast aus Nerv B enthält eine große Anzahl von Axonen. Die aus Ansatz und Ursprung ersichtliche gemeinsame Funktion verschiedener Beinmuskeln spiegelt sich auch in der Innervation aus gemeinsamen Seitenästen von Nerv B wieder.Soweit möglich werden die vermutlich homologen Beinmuskeln aus Untersuchungen anderer Autoren an anderen Arten gegenübergestellt.

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Anatomy of the leg muscles and their innervation in the tarantulaDugesiella hentzi (Ch.) (Araneae, Aviculariidae)

Summary All muscles in the walking legs of the adult tarantulaDugesiella hentzi (Ch.) are described according to their position, function, and innervation pattern. Each leg contains 30 muscles. With the exception of one (M. 30) all of them receive their motor innervation through multiple branches from the main motor nerve B. Muscle 30 is innervated through the mixed nerve A. Each branch leaving nerve B contains a large number of axons.Similarities in the function of different muscles as derived from their attachment at particular leg joints are reflected in the innervation pattern by common branches of nerve B.The leg muscles fromDugesiella are homologized with those of six other species of spiders from different families.

     

The uptake of copper by cell suspension cultures of Phaseolus vulgaris L. cv. SAXA

In experiments with cell suspension cultures of Phaseolus vulgaris L. cv. SAXA it could be demonstrated that gas-shocks caused by aeration decrease the uptake of copper. An aeration period of 30 h prior to the addition of copper was found to be sufficient to reestablish the copper uptake system. EDTA/sucrose solutions seemed to be adequate to remove the adsorbed copper. The time course of the uptake of copper showed saturation behaviour, whereas the velocity of the uptake was dependent on the given concentration of copper.     

Possible sites of ultrafiltration in Tubifex tubifex Müller (Annelida,Oligochaeta)

Summary The endothelia of Tubifex tubifex Müller consist of myoendothelial cells, chloragocytes, or podocytes. The latter seem to occur only as windows on the ventral vessel which has an endothelium of myoendothelial cells elsewhere. The podocytes are large cells, with several processes on the inner side which ramify into several pedicels. These are aligned upon the outside of the basement membrane which lines the inside of the endothelium. The gaps between adjacent pedicels are about 40 nm wide. In capillaries fenestrated endothelia occur with irregular spacings measuring up to 0.4–1 m. A diaphragm in podocytes or capillary fenestrations do not seem to exist. The basement membrane is the only continuous layer lining the blood vessels and capillaries of Tubifex with a rather uniform diameter in the range of 50 nm. It is the only permeability barrier between blood and coelomic fluid.     

Metabolic interlock between the acetolactate synthase isoenzymes and lysine biosynthesis in Escherichia coli K-12

Summary Some of the strains containing mutations in the genes for the acetolactate synthase isoenzymes are temperature sensitive (ts). Suppression of the acetolactate synthase defect due to one of these mutations suppresses also the ts phenotype; moreover, a genetic cross shows that the two phenotypes cannot be dissociated.The ts phenotype is accompanied by a decreased efficiency of transduction with Pl phage. Observations at the light microscope show formation of abnormal cells. Under specific conditions diaminopimelate stimulates growth and restores normal transduction efficiency. The rate of diaminopimelate formed and excreted by non-growing cells decreases when an acetolactate synthase mutation is present.We give evidence that the ts phenotype is due to an increased formation of lysine from diaminopimelate; this causes a starvation for the latter and therefore cell wall abnormalities. In fact, even at the permissive temperature, the lysine pool is 8x increased in a strain with an acetolactate synthase defect, while a slight decrease in the diaminopimelate pool is observed. Moreover, introduction into a ts strain of a mutation in lysA (the gene coding for diaminopimelate decarboxylase) cures the ts phenotype. Finally among the temperature resistant revertants we found some lysine auxotrophs.     

Isolation and visualisation of alkali stable protein/DNA complexes

Distinct polypeptides, 54,000–68,000 daltons in size, are alkali-stably bound to eukaryotic DNA. DNA fragments several hundred base pairs in length associated with these polypeptides are preferentially retained on glass fibre filters from solutions containing 1 M sodium chloride. About 50 percent of the protein/DNA complexes present in total DNA are retained on filters together with about 2 percent of the DNA. This preferential binding is demonstrated (a) by the ratio of ³H and ³⁵S radioactivity retained on filters after filtration of DNA from [³H]thymidine and L-[³⁵S]methionine labelled cells, (b) radioiodination of the material retained on filters and passing filters respectively and (c) by electron microscopical visualisation of the polypeptide component in the complexes after chemical modification with dinitrofluorobenzene (DNFB) followed by incubation with dinitrophenyl (DNP) specific antibodies.     

Utilization of limiting concentrations of ortho-phosphate and production of extracellular organic phosphates in cultures of marine diatoms

The utilization of ortho-phosphate by two coastal marine diatomspecies, Nitzschia closterium and Cyclotella cryptica, was studiedin batch cultures. The hypothesis was tested that thresholdconcentrations in the phosphate uptake determine the lower limitof environmental phosphate, permitting the existence of species.The turn-over time of residual medium phosphate in culturesis {small tilde}10 min, indicating a rapid equilibration ofconcentration dependent on uptake with leakage of ortho-phosphate.Increasing phosphate starvation in cultures diminished the residualortho-phosphate in the range of {small tilde}60–<2nmol l^–1, as measured radiochemically after elution onSephadex® G-10 gel. These concentrations encompass the rangeof limiting phosphate concentration in continuous cultures ofthe few microalgae, for which these concentrations are actuallymeasured. The diatoms excreted {small tilde}20–100 nmolI^–1 of organic phosphate. One dominating compound, probablyan unusual nucleotide, was incompletely or not resorbed underphosphate starvation. In contrast, Nitzschia closterium excretedunder ample phosphate supply a series of three related compounds,probably phospholipids, that were resorbed under depletion.The association of the organic phosphates with macromolecularexudates is interpreted, along with the other observations,as an indication for a hardly explored periplasmatic phosphatemetabolism in these algae. ³Dedicated to Prof. Dr. H.-A. von Stosch in honour of his 75thbirthday. ⁴This study was conducted at the University of Marburg undersupport of the Humboldt Foundation Publication no. 64 of theproject "Biological Research of the Eems-Dollard Estuary".     

Stimulation of human nitric oxide synthase by tetrahydrobiopterin and selective binding of the cofactor.

To check the stimulatory potency of the tetrahydro forms of the two major pteridines occurring in human tissues, neopterin and biopterin, NO synthase was purified 6000-fold from human cerebellum. Tetrahydrobiopterin stimulated the activity up to 4.5-fold in a concentration dependent manner with a maximum above 1 microM, whereas tetrahydroneopterin was completely inactive in concentrations up to 100 microM. Tetrahydrobiopterin, but not neopterin derivatives, were copurified with the NO synthase activity. Our results demonstrate that human cerebellum contains a tetrahydrobiopterin dependent NO synthase activity.     

Effects of permethrin on aquatic organisms in a freshwater stream in south-central Alaska.

Permethrin (0.5%) was applied to individual Lutz spruce, Picea x lutzii Little, to protect them from attack by spruce beetles, Dendroctonus rufipennis (Kirby). Residue levels were monitored in a freshwater stream above, adjacent to, and below the treatment site at intervals before, during, and after treatment. Maximum residue levels in the stream within the treatment site ranged from 0.05 +/- 0.01 ppb 5 h after treatment to 0.14 +/- 0.03 ppb 8-11 h after treatment, with a decrease to 0.02 +/- 0.01 ppb 14 h after treatment. Levels of permethrin in standing pools near the stream within the treatment site were 0.01 +/- 0.01 ppb. Numbers of drifting aquatic invertebrates increased 2-fold during treatment and 4-fold 3 h after treatment and declined to before spray numbers within 9 h. Terrestrial insects did not appear to respond to treatments because none was found in stream drift samples. Trout fry (Dolly Varden), aquatic insect larvae, and periphyton (attached algae) within and below the treatment site during and after treatment did not show signs of mortality compared with an upstream untreated control site.