Ein longitudinal verlaufendes Element des Transversalsystems in der Skeletmuskulatur von Guppyi (Lebistes reticulatus)

Summary In the lateral body muscle of fish (Lebistes reticulatus) about 8 days old, a longitudinal non-fibrillar element could be observed over a length of 18 sarcomers. Its staining properties and its junction with the transverse tubules of the T-system imply that it is a part of the T-system.     

Attività di neurosecrezione nel sistema nervoso di un Turbellario rabdocelo:Mesostoma lingua (Abildg.)

Summary This investigation is concerned with the neurosecretory activity in the cerebral ganglion of a rhabdocoel turbellarian:Mesostoma lingua (Abildg.).It was observed that the neurosecretory activity is primarily localized in the pear-shaped cells, situated near to the region where the external anterior cords arise from the dorsolateral tract of the cerebral ganglion.The neurosecretory material appears to be transported — via the ventral cords — to the transverse cord behind the pharynx, where it is stored. Then, probably, it flows down into the parenchyma.     

Water compartments in the myelinated nerve. III. Pulsed NMR result

Summary 3 experimentally distinct transverse relaxation components of the water in frog sciatic nerve are obtained by Carr-Purcell-Meiboom-Gill technique. The relative weights of these components: 29%; 50%; 21% fit well with water compartments in this tissue as revealed by previous methods.The previous communication in this series: V. Vasilescu, D.-G. Mârgineanu and Eva Katona, Experientia33, 192 (1977).     

Native skeletal muscle dihydropyridine receptor exists as a supramolecular triad complexRID="†"ID="†" Research Article

One of the central elements of excitation-contraction coupling, the voltage-sensing dihydropyridine receptor, is believed to exist as a high-molecular-mass complex in the triad junction. Although freeze-fracture electron microscopical analysis suggests a tetrad complex, no direct biochemical evidence exists demonstrating the actual size of the native membrane complex. Using a combination of various two-dimensional gel electrophoresis techniques, we show here that the principal α ₁-subunit of the dihydropyridine receptor and its auxiliary α ₂-subunit form a triad complex of approximately 2800 kDa under native conditions. Established Ca²⁺-ATPase tetramers and calsequestrin monomers were employed for the internal standardization of the gel systems used. Thus, the large voltage-sensing complex appears to be tightly associated, since it does not disintegrate during subcellular fractionation and native electrophoresis procedures. Our findings support the cell biological hypothesis that native dihydropyridine receptor units form a tetrad structure within the transverse tubules. Received 10 October 2000; revised 28 November 2000; accepted 4 January 2001     

Testing the clockface model of amphibian limb regeneration

Summary Contrary to the predictions of the clockface model, rotating a regenerate by 90° produces duplications identical to those resulting from 180° axial reversals. Exchanging regenerates between arms indicates the presence of 2 determined transverse axes.     

Water compartments in the myelinated nerve. III. Pulsed NMR results.

3 experimentally distinct transverse relaxation components of the water in frog sciatic nerve are obtained by Carr-Purcell-Meiboom-Gill technique. The relative weights of these components: approximately 29%; approximately 50%; approximately 21% fit well with water compartments in this tissue as revealed by previous methods.     

On two transverse nonlinear models of axially moving beams

Nonlinear models of transverse vibration of axially moving beams are computationally investigated.A partial-differential equation is derived from the governing equation of coupled planar motion by omitting its longitudinal terms.The model can be reduced to an integro-partial-differential equation by averaging the beam disturbed tension.Numerical schemes are respectively presented for the governing equations of coupled planar and the two governing equations of transverse motion via the finite difference meth...     

Chromosomes of the squirrelFunambulus palmarum bellaricus Wroughton

Summary The chromosome complement ofFunambulus palmarum bellaricus Wroughton (Mammalia-Rodentia-Sciuridae) has been studied for the first time, and the diploid number established to be 54, in contrast to the subspeciesF. p. palmarum which has 2n=46 chromosomes. The known karyotypes within the genusFunambulus are compared. We thank Prof. G. T. Tonapi for providing the laboratory facilities and the Zoological Survey of India, Western Regional Station, Pune for identifying the specimens.     

Effect of the juvenoid methoprene on the hemolymph composition of the cabbage maggotDelia radicum (Diptera: Anthomyiidae)

Summary Treatment of post-feeding larvae of the cabbage maggotDelia radicum with methoprene did not affect the capacity of the insect to pupate, but suppressed eclosion to the adult stage. The concentration of hemolymph trehalose was significantly decreased by methoprene treatment, although hemolymph protein and amino nitrogen levels were unaffected.19 December 1986The authors are grateful to D. C. Read of the Research Centre, Agriculture Canada, Charlottetown, P.E.I., Canada for supplying eggs ofD. radicum for the stock colony. TheD. radicum colony was maintained at the Agriculture Canada Research Station, St. John's West, Newfoundland, Canada. The sample of methoprene was donated by Zoecon Corp., Palo Alto, California, U.S.A. This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (Operating grant A6679).     

Nonlinear combination parametric resonance of axially accelerating viscoelastic strings constituted by the standard linear solid model

Nonlinear combination parametric resonance is investigated for an axially accelerating viscoelastic string. The governing equation of in-planar motion of the string is established by introducing a coordinate transform in the Eulerian equation of a string with moving boundaries. The string under investigation is constituted by the standard linear solid model in which the material, not partial, time derivative was used. The governing equation leads to the Mote model for transverse vibration by omitting the lo...     

On the specific attraction of the males of the six-toothed spruce bark beetle,Pityogenes chalcographus (L.) to a mixture of synthetic pheromones of the eight-toothed spruce bark beetle,Ips typographus (L.) (Coleoptera,Scolytidae)

Summary Traps containing a mixture of attractants forIps typographus also caught other species of bark beetles. The numbers ofPityogenes chalcographus, Pityogenes conjunctus, andTrypodendron lineatum were too high to be interpreted as accidental captures. The males of the polygamousP. chalcographus were specifically attracted, indicating that theI. typographus pheromone or one of its components acts as a kairomone and primary attractant for the pioneering males ofP. chalcographus.     

Variance to mean ratio and the spatial distribution of animals

Summary Biological and statistical aspects of the application of variance to mean ratio to describe spatial distribution of animals are discussed. It is shown that the parameterb inTaylor's power laws ²=a m ^b shows intra-specific variation depending on the distribution of the constituent units of the population.a andb are only parameters of a very empirical way of describing the relation between variance and mean, which itself is an indicator for spatial distribution. Hence,a andb depend on the distribution behaviour of the animals, and not vice versa.Acknowledgments: The work was developed whilst I was at the Department of Entomology, University of Nairobi. I am grateful to ProfessorT. R. Odhiambo for his interest. I thank the referee for comments.     

Effects of acute hypothermia on the chick ERG

Zusammenfassung Mit der Abnahme der Körpertemperatur verminderte sich gleichzeitig die Amplitude derb- undc-Wellen des ERG. Zwei kleinere, von dena- undb-Wellen abgespaltene Komponenten wurden während der Abkühlung festgestellt, während nach Wiederherstellung der Hypothermie das ERG die normale Wellenform registrierte.

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The author is greatly indebted to Prof.I. Hanawa for his valuable advice and encouragement during this study. The author is also indebted to the Goto Hatchery Ind., Gifu City, for supplying the chicks.     

Effect ofl- andd-thyroxine on the supraoptic neurosecretory ganglion cells of the rat

Zusammenfassung Mittels grosser Dosen vonl- undd-Thyroxin erhielt man keine deutlichen Veränderungen in der Menge und Verteilung von neurosekretorischem Material in den Zellen des Nucleus supraopticus bei der männlichen Ratte. Das Volumen der Kerne dieser Zellen nahm dagegen zu, besonders bei mitl-Thyroxin behandelten Ratten. Diese Veränderungen sprechen für eine vermehrte neurosekretorische Aktivität dieser Zellen.

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This investigation was supported by a grant from Sigrid Jusélius Foundation, Helsinki. The authors wish also to express appreciation to Pharmacia Company, Sweden for generous supplies of Na-d-thyroxine used in this study, and to MissS. Nurminen for technical assistance.     

Formation of enantiomeric sesquiterpenes in the secretions of scale insects

Summary The volatile oil present in the secretion of a scale insect,Ceroplastes ceriferus Anderson (fam. Coccidae), has been found to consist of a number of sesquiterpenes which are enantiomeric with respect to those fromC. rubens Maskell, which infests the same host tree. The present investigation strongly suggests that each insect possesses a specific set of C-C cyclases for the sesquiterpenoids.Acknowledgments. The authors would like to express their thanks to Dr Y. Asakawa (Tokushima Bunri Univ.) for providingC. ceriferus and to Prof. S. Takagi (Hokkaido Univ.) for the identification of it.     

Structure and assembly of the 20S proteasome

The barrel-shaped 20S proteasome is one of the two components of a larger 26S particle, the multicatalytic 2000-kDa protease complex. The proteolytic sites are located in the inner chamber of the 20S particle and are only accessible via narrow entrances. This paper reviews the current knowledge concerning proteasome formation, proteolytic activities, structural aspects and assembly. Eukaryotic proteasomes are made up by four rings each of which contains seven different subunits occurring at fixed positions. While the outer rings contain α-type subunits, the inner ones comprise β-type subunits. The current assembly model for eukaryotic 20S proteasomes is based upon the detection of 13S and 16S intermediates, respectively, in addition to previous findings with archaebacterial and eubacterial proteasome assembly. The available data suggest a cooperative assembly of the α-type and β-type subunits into half proteasome-like complexes followed by dimerization into proteasomes. During or after dimerization of half proteasomes, the β-type subunits are processed. The prosequence of the β-type subunits is essential for the assembly process and prevents protease activity of immature proteasomes.     

Observations on the toxicity and metabolic relationships of polygodial,the chemical defense of the nudibranchDendrodoris limbata

Summary Polygodial (1), the defense metabolite stored in the skin of the nudibranchDendrodoris limbata, is toxic for the mollusc itself when injected into the hepatopancreas. Biosynthetic experiments using labeled mevalonic acid were devised to investigate a possible metabolic relationship between1 and the mixture of sesquiterpenoidic esters2, stored in the hepatopancreas. The results suggest that1 and2 are biosynthesized by independent pathways.Thanks are due to G. Villani for supplyingDendrodoris limbata and to A. Trabucco for technical assistance.     

Cell adhesion in the life cycle ofDictyostelium

three forms of cell adhesion determine the life cycle ofDictyostelium: i) adhesion of bacteria to the surface of the growing amoebae, as the prerequisite for phagocytosis;ii) cell-substrate adhesion, necessary for both locomotion of the amoebae and migration of the slug;iii) cell-cell adhesion, essential for transition from the unicellular to the multicellular stage. Intercellular adhesion has received the most attention, and fruitful approaches have been developed over the past 25 years to identify, purify and characterize cell adhesion molecules. The csA glycoprotein, in particular, which mediates adhesion during the aggregation stage, is one of the best defined cell adhesion molecules. The molecular components involved in phagocytosis and cell-substratum adhesion are less well understood, but the basis has been laid for a systematic investigation of both topics in the near future.     

Effect of NPV of the armywormMythimna (Pseudaletia) separata on the silkwormBombyx mori

Summary Nuclear polyhedrosis virus (NPV) material of the armywormMythimna (Pseudaletia) separata was administered in the form of PIBs and free virus rods to the larvae of silkwormBombyx mori. Routes used for administration were topical, intrahaemocoelic and oral. The larvae were treated with following concentrations: 10×10⁵ PIBs/L, 10×10⁶ PIBs/L, 10×10⁷ PIBs/L, 10×10⁸ PIBs/L. In all the 3 experiments, the larvae showed neither any signs and symptoms, nor mortality due to polyhedrosis. Thus it appears that the NPV ofM. (P.) separata is safe for the silkwormB. mori.Acknowledgments. We are grateful to the Karnatak University, Dharwad, for awarding UGC Junior Fellowship to S.G.D. and for financial assistance made available to S.B.M. We thank Professor M. Appaswamy Rao, Department of Zoology, for providing the necessary facilities. Our thanks are also due to Mr B. Chavannawar for supplying mulberry leaves and to the Government Silk Farm, Hindalaga, Belgaum, for providing silkworm eggs.