Biochemical, biological, and immunological properties of chemically deglycosylated human choriogonadotropin

A chemical method of deglycosylation of human choriogonadotropin (hCG) was used to assess the role of carbohydrate moiety in the maintenance of quaternary structure and functional parameters such as receptor binding, immunological activity, and in vitro biological response. Treatment of purified hCG with anhydrous HF at 0 degrees C for 60 min was effective in removing more than 75% of the carbohydrate moiety. This extent of deglycosylation altered its chromatographic characteristics as revealed by retarded behavior on Sephadex G-100 and failure to be retained on concanavalin A-Sepharose. The electrophoretic heterogeneity present in native hCG was markedly reduced by deglycosylation. The deglycosylated hCG was stable in the lyophilized form and retained its quaternary structure as revealed by the fluorescence probe 8-anilino 1-naphthalene sulfonic acid, receptor binding, and immunological activities. Unlike receptor binding and immunological activities, which were fully retained, the ability of the hormone to stimulate cyclic AMP accumulation in vitro in rat interstitial cells was completely abolished.     

Potential interspecific competition and host specificity: hispine beetles on Heliconia

Abstract. 1. Adults of rolled-leaf hispine beetles (Chrysomelidae, Coleoptera) spend their lives in the scrolls formed by immature leaves of Heliconia (Heli-coniaceae, Monocotyledonae) in Tropical America. As many as eight hispine species can intermingle in the host scrolls at a single site. Scrolls of single host species are invariably occupied by adults of more than one hispine species, and as many as five species can simultaneously occupy one scroll.
2. I made virgin scrolls, which had never contained any insects, by growing leaves under the cover of plastic bags.
3. Thirty-seven combinations of single hispine and Heliconia species were experimentally created in the virgin scrolls, at two sites and in two seasons, in Costa Rica. Combinations included all abundant host species at the sites.
4. All beetles left all leaves of the twenty-eight unnatural beetle—host combinations, within 24 h. On the other hand, none of the nine natural combinations was completely abandoned within the experimental period.
5. Thus, host specificity is not broader in the absence of similar hispine species that might be competitors, and interspecies competition does not affect this obvious aspect of resource utilization for these phytophagous insects.     

Perfusion method for preparing pig brain cortex for Golgi-Cox impregnation

The perfusion procedure described in this paper produces high quality impregnation of pig visual and somatosensory cortical neurons with a Golgi-Cox solution. Starting within 30 min after death, pig heads were perfused with a fixative solution composed of a mixture (v/v) of liquid phenol, 5%; formalin, 14%; ethylene glycol, 25%; methanol, 28%; and water, 28% for two periods of 4 hr each. After perfusion, the heads were chilled for at least 18 hr. The entire brain was removed from the skull and then placed in 10% buffered formalin, where it remained for at least 10 days before taking the blocks that were to be immersed in the Golgi-Cox solution. Three weeks spent in the Golgi-Cox solution typically produced uniform neuron impregnation. The tissue blocks were then embedded in celloidin and sectioned at 120 micron. This procedure avoids the following difficulties: Golgi-Cox methods that produced excellent results with rodent or primate tissue were unsuccessful with pig tissue, placing fresh tissue in Golgi-Cox solution resulted in incomplete neuron impregnation, and immersion fixation in 10% buffered formalin without perfusion resulted in excessive staining of glia.