Genotoxic effects of dithane M-45 on the bone marrow cells of mice in vivo

Genotoxic effects of dithane M-45 were studied on the bone marrow cells of male albino mice (Lacca strain) in vivo. Different doses (30 mg, 40 mg and 300 mg/kg b.wt) of dithane M-45 were injected intraperitoneally and their effects were investigated after time intervals of 1, 2, 5 and 10 days. The chromosomal aberrations observed in the bone marrow cells of male mice after treatment with dithane M-45 were fragments, rings, dicentric chromosomes, terminal chromatid deletions, chromatid gaps and breaks. In addition to these chromosomal aberrations, physiological effects such as uneven stretching of chromatin material, end-to-end chromosomal associations, exchange configurations, clumping, stickiness and centromeric associations were also observed.     

Molecular organization of vomeronasal chemoreception

The vomeronasal organ (VNO) has a key role in mediating the social and defensive responses of many terrestrial vertebrates to species- and sex-specific chemosignals. More than 250 putative pheromone receptors have been identified in the mouse VNO, but the nature of the signals detected by individual VNO receptors has not yet been elucidated. To gain insight into the molecular logic of VNO detection leading to mating, aggression or defensive responses, we sought to uncover the response profiles of individual vomeronasal receptors to a wide range of animal cues. Here we describe the repertoire of behaviourally and physiologically relevant stimuli detected by a large number of individual vomeronasal receptors in mice, and define a global map of vomeronasal signal detection. We demonstrate that the two classes (V1R and V2R) of vomeronasal receptors use fundamentally different strategies to encode chemosensory information, and that distinct receptor subfamilies have evolved towards the specific recognition of certain animal groups or chemical structures. The association of large subsets of vomeronasal receptors with cognate, ethologically and physiologically relevant stimuli establishes the molecular foundation of vomeronasal information coding, and opens new avenues for further investigating the neural mechanisms underlying behaviour specificity.     

Further applications of pentachlorophenyl active esters in the synthesis of peptides

Zusammenfassung Pentachlorophenylaktivierte Ester von N-Carbobenzoxy-aminosäuren verbinden sich in guten Ausbeuten mit Dicyclohexylaminsalzen von Aminosäuren. Um die Hydrolyse zu vermeiden, wurde eine Kombination der Methoden der gemischten Anhydriden und pentachlorophenylaktivierten Estern zur Verlängerung der Peptidenketten benützt.     

The bipolar mitotic kinesin Eg5 moves on both microtubules that it crosslinks

During cell division, mitotic spindles are assembled by microtubule-based motor proteins. The bipolar organization of spindles is essential for proper segregation of chromosomes, and requires plus-end-directed homotetrameric motor proteins of the widely conserved kinesin-5 (BimC) family. Hypotheses for bipolar spindle formation include the 'push-pull mitotic muscle' model, in which kinesin-5 and opposing motor proteins act between overlapping microtubules. However, the precise roles of kinesin-5 during this process are unknown. Here we show that the vertebrate kinesin-5 Eg5 drives the sliding of microtubules depending on their relative orientation. We found in controlled in vitro assays that Eg5 has the remarkable capability of simultaneously moving at approximately 20 nm s(-1) towards the plus-ends of each of the two microtubules it crosslinks. For anti-parallel microtubules, this results in relative sliding at approximately 40 nm s(-1), comparable to spindle pole separation rates in vivo. Furthermore, we found that Eg5 can tether microtubule plus-ends, suggesting an additional microtubule-binding mode for Eg5. Our results demonstrate how members of the kinesin-5 family are likely to function in mitosis, pushing apart interpolar microtubules as well as recruiting microtubules into bundles that are subsequently polarized by relative sliding.     

Sensory canals of the head inWallagonia attu (day)

Zusammenfassung Das Studium der Sinneskanäle im Kopf desWallagonia attu (Day) bis zu 28 mm Länge ergab, dass der präoperkulare Kanal sich nicht bis an den temporalen Hauptkanal erstreckt, dass der mandibulare Kanal sich nicht mit dem präoperkularen Kanal vereinigt und der infraorbitale Kanal nicht vollständig ausgebildet ist und sich nicht mit dem supraorbitalen vereinigt.     

Presence of specialized cellular complexes in the tracheal gills of stonefly nymph,Paragnetina media (Walker)

Résumé Les coupes ultraminces d'un filament trachéobranchial d'une nymphe de plécoptère ont rélévé dans l'épithélium branchial des complexes cellularies spécialisés. Ces complexes sont présents tout le long du bord du filament, juste au-dessous de la cuticule et n'avaient pas encore été observés chez les plécoptères. Ils ressemblen aux «cellules de chlore» des poissons et à celles des nymphes des éphémères.     

A simple method for reconstructing serial sections

Résumé On décrit une méthode simple de reconstruction des sections sériées qui évite l'exécution fastidieuse d'un grand nombre de dessins. Bien qu'elle ne donne pas une image à trois dimensions, cette méthode est aussi utile qu'une autre pour étudier l'anatomie et les relations structurales par reconstruction de sections sériées.     

Occurrence of synapses in olfactory epithelium of fish

Zusammenfassung Nachweis von Synapsen in der Riechschleimhaut des FischesChanna punctatus, die als Verbindung zwischen primärer und sekundärer Riechzelle aufgefasst werden.

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We wish to thank Dr.Rameshwar Singh, our colleague in this department, for his helpful suggestions.