Effects of chronic melatonin and saline injections on pituitary adrenal secretion

Zusammenfassung Es wurde festgestellt, dass Melatonin, ein angebliches Hormon aus der Pinealis, keine spezifische Wirkung auf die Sekretion von ACTH aus dem Hypophysenvorderlappen hat.     

Magnetic resonance microscopy: in vivo sectioning of a developing insect

Summary The utility of magnetic resonance imaging vis-a-vis insect morphology and development was investigated. MRI is a noninvasive technique that distinguishes between tissues based on proton content and proton environment. At present a resolution of 100 m is achievable. The technique avoids fixation artifacts and allows the detection of motion within the organism.     

Magnetic resonance microscopy: in vivo sectioning of a developing insect

The utility of magnetic resonance imaging vis-a-vis insect morphology and development was investigated. MRI is a noninvasive technique that distinguishes between tissues based on proton content and proton 'environment'. At present a resolution of 100 micron is achievable. The technique avoids fixation artifacts and allows the detection of motion within the organism.     

Defensive substances of opilionids

Summary The defensive secretions of 4 species of opilionids were analyzed.Leiobunum ventricosum andHadrobunus maculosus produce 4-methylheptan-3-one, whileL. calcar produces E-4,6-dimethyl-6-octen-3-one.L. longipes produces E-4,6-dimethyl-6-nonen-3-one, a new natural product.Paper No. 51 of the seriesDefensive Mechanisms of Arthropods.Acknowledgments. Partial support by the National Institutes of Health (Grant Nos. AI-12020 and AI-02908 and Fellowship No. 1-F32-CA05139 to T.H.J.) and the National Science Foundation (Grant No. BMS 75-15084) is gratefully acknowledged. We thank Dr.W. A. Shear for identifying the opilionids.     

Benzoyl cyanide in the defensive secretion of polydesmoid millipeds

Summary A novel cyanogenetic compound, benzoyl cyanide, was isolated from the defensive secretion of 3 polydesmoid millipeds (Pseudopolydesmus serratus, Apheloria corrugata and A. trimaculata). The secretion of the 3 species also contains mandelonitrile and benzaldehyde, and that of P. serratus contains mandelonitrile benzoate, benzoic acid, isovaleric acid, myristic acid and stearic acid.Paper No. 52 of the series Defense Mechanisms of Arthropods.The study was supported in part by the National Institutes of Health (grants AI-12020 and AI-02908 and Fellowship 1-F-32-CA05139 to T. H. J.) and the National Science Foundation (grant BMS 75-15084).     

Ultrasound: its role in the courtship of the arctiid moth,Cycnia tenera

Summary MaleCycnia tenera (Lepidoptera: Arctiidae) were shown to produce ultrasonic clicks during courtship. The ultrasound enhances male courtship success, but only in the absence of male-produced pheromonal cues.     

Regulated portals of entry into the cell

The plasma membrane is the interface between cells and their harsh environment. Uptake of nutrients and all communication among cells and between cells and their environment occurs through this interface. 'Endocytosis' encompasses several diverse mechanisms by which cells internalize macromolecules and particles into transport vesicles derived from the plasma membrane. It controls entry into the cell and has a crucial role in development, the immune response, neurotransmission, intercellular communication, signal transduction, and cellular and organismal homeostasis. As the complexity of molecular interactions governing endocytosis are revealed, it has become increasingly clear that it is tightly coordinated and coupled with overall cell physiology and thus, must be viewed in a broader context than simple vesicular trafficking.     

Genetic mechanisms of floral trait correlations in a natural population

Genetic correlations among traits are important in evolution, as they can constrain evolutionary change or reflect past selection for combinations of traits. Constraints and integration depend on whether the correlations are caused by pleiotropy or linkage disequilibrium, but these genetic mechanisms underlying correlations remain largely unknown in natural populations. Quantitative trait locus (QTL) mapping studies do not adequately address the mechanisms of within-population genetic correlations because they rely on crosses between distinct species, inbred lines or selected lines (see ref. 5), and they cannot distinguish moderate linkage disequilibrium from pleiotropy because they commonly rely on only one or two episodes of recombination. Here I report that after nine generations of enforced random mating (nine episodes of recombination), correlations between six floral traits in wild radish plants are unchanged, showing that pleiotropy generates the correlations. There is no evidence for linkage disequilibrium despite previous correlational selection acting on one functionally integrated pair of traits. This study provides direct evidence of the genetic mechanisms underlying correlations between quantitative traits in a natural population and suggests that there may be constraints on the independent evolution of pairs of highly correlated traits.     

Galaxy mass deduced from the structure of Einstein ring MG1654+1346

ELLIPTICAL galaxies acting as gravitational lenses occasionally produce spectacular images-Einstein rings-of distant objects. Giant arcs(1) and radio rings(2) have been observed. A wide variety of image morphologies is possible, the generation of which is qualitatively understood in terms of large magnifications at caustic and critical lines in the lensing geometry(3-5). From the angular size of the image, and with knowledge of the distances of the lensed and lensing object, rough estimates of the mass of the lensing galaxy can be obtained. We have made high-resolution radio-interferometric observations of MG1654 + 1346 (ref. 6) a radio quasar in near-perfect alignment with an elliptical galaxy, and show that radio emission is distorted into a narrow Einstein ring that lies within a diamond-shaped region bounded by caustic lines. From the details of the ring structure, a new model for the lensing geometry is deduced which leads to a more accurate estimate of the mass of the lensing galaxy.