Temporal activity patterns of Dipodomys ordii population

Temporal activity patterns for Dipodomys ordii were generally bimodal during the summer, with the highest peak occurring during early predawn hours when conditions were optimum for water conservation. Removal of dominant members in the population resulted in a substantial shift in the activity pattern to increased activity during the evening hours.     

Inhibition of mammalian acetylcholinesterase by phenylmethanesulfonyl fluoride

Resumen El fenilmentano sulfonil fluoro (FMSF) 4×10^–5 M inhibe a la acetilcolinesterasa (E. C. 3.1.1.7) de cerebro de rata en más de 50%, y 9×10^–4 M más de 90%. La constante de reacción inhibidor enzima es de 4.7×10² (1 mol^–1 min^–1). La colinesterasa (E. C. 3.1.1.8) de cerebro de rata es insensible a FMSF.

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Supported by NIMH Grant No. 1 RO3 MH 19125, by Comisión Nacional de Investigación Cientiffica Proyecto No. 80, and by Comisión de Investigación Cientiffica Universidad de Chile, Proyecto No. 95.     

Sclerotization and coloration of the insect cuticle

Summary Evidence indicating linkage between the processes of cuticle hardening and coloration are reviewed. Data and observations for the mutants black and ebony inDrosophila melanogaster are used to construct a possible model for the relationship between these developmental events.     

Inhibition of IgM antibody-mediated aggregation ofTrypanosoma gambiense in the presence of complement

This paper deals with the immune reaction betweenTrypanosoma gambiense and monoclonal IgM mouse antibody at equivalence with or without rabbit complement. Antibody-mediated trypanosome clumps formed in the absence of complement, and were readily dissociated by complement to become free. In the presence of complement, on the other hand,T. gambiense were not aggregated by the antibody. Free parasites adhered readily to cultured peritoneal macrophages. Complement-mediated dissociation of the clumped trypanosomes in the equivalence area released a large number of previously bound surface antigens. These antigens were capable of binding again to fresh IgM antibody. Experimental results further indicated that the complement system caused a functional alteration, changing the multivalent nature of the IgM antibody in the immune complex into a univalent one. This phenomenon is of great advantage to the infected host in clearing pathogens in vivo, as it allows more antibodies to attach to trypanosomes and subsequently initiate complement activity.     

A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s(-1)

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.     

A new puffing pattern induced by temperature shock and DNP in drosophila

Riassunto Si è notato che shocks di temperatura possono indurre una variazione di «puffing pattern» in ghiandole salivari di Drosophila. Tali «puffing» sono perfettamente reversibili e rappresentano zone di intensa sintesi di RNA. Si è notato che DNP e Na salicilato portano a simili variazioni di «puffing pattern».     

Clark's Nutcrackers harvest sugar pine seeds from cones

This is the first report of Clark’s Nutcrackers ( Nucifraga columbiana ) harvesting seeds from the cones of sugar pine ( Pinus lambertiana ), based on observations over several years in Crater Lake National Park, Oregon. The harvesting period in late September corresponded to peak cone-opening dates. Nutcrackers placed harvested seeds in their throat pouches, a behavior associated with seed caching.