Receptor-binding region of insulin.

X-ray analysis, circular dichroism, receptor binding and biological potencies of chemically modified insulins suggest that the conformation of the insulin molecule is critical to the formation of both the zinc insulin hexamer and the insulin-receptor complex. Results are consistent with an insulin receptor-binding region including many of the hydrophobic residues important to dimerisation in addition to more polar surface residues. There is a further possibility of formation of an antiparallel sheet structure between the insulin and receptor molecules in the complex similar to that between monomers in the insulin dimer.     

Unclassed matrix shading and optimal ordering in hierarchical cluster analysis

A method is presented for the graphic display of proximity matrices as a complement to the common data analysis techniques of hierarchical clustering. The procedure involves the use of computer generated shaded matrices based on unclassed choropleth mapping in conjunction with a strategy for matrix reorganization. The latter incorporates a combination of techniques for seriation and the ordering of binary trees.Partial support for this research was provided by NIJ Grant #82-IJ-CX-0019 and NSF Grant #SES82-06067. The authors wish to acknowledge the assistance of Professors L.J. Hubert, R.G. Golledge, and W.R. Tobler.     

Persistent inverse maternal effect on corticosterone production in vitro

Summary Adrenal cells from C57BL/Tb mice produced more steroid than those from DBA/2J mice. Reciprocal differences between both backcross and F1 hybrids showed a persistent maternal effect. Mothers with high output produce offspring with reduced hormone production when adult. Corticosterone output thus depends on maternal phenotype as well as on the genotype of the isolated cells.We thank Margaret MacKendrick for her help and the Medical Research Council for a research studentship for PRWW.     

In memoriam: William Wallace Newby (1902-1977)

W. W. Newby, professor of biology at the University of Utah from 1927 to 1971, was renowned as a great teacher and a clear and forceful writer and for his meticulous research in invertebrate embryology. Ancillary skills were counseling (especially of premedical students), illustrating, wood crafting, and paper preserving. Some of his writings pertained to the history of research in the biological sciences at the University of Utah. His specialty areas in teaching were embryology and genetics, and he served as chairman of the Department of Genetics and Cytology from the year of its creation in 1948 until 1962. The most outstanding example of his research pertained to the early embryology of the echiuroid worm Urechis caupo .         

Algal composition of microbiotic crusts from the Central Desert of Baja California, Mexico

A total of 66 algal species representing 32 genera were recovered from soils of 10 sites in the Catavi?a region of the Central Desert of Baja California, Mexico. The most common species encountered were the cyanophytes Nostoc commune and Schizothrix calcicola , the chlorophyte Myrmecia astigmatica , and the diatoms Hantzschia amphioxys, Hantzschia amphyoxys f. capitata, Luticola cohnii, Luticola mutica , and Pinnularia borealis var. scalarts . Nine species not found in any previous studies of North American desert soils were present in our study sites, including 3 taxa new to science: Cylindrocystis brebissonii var. deserti , var. nov.; Elakatothrix obtusata , sp. nov.; and Fasciculochloris mexicana , sp. nov. Attempts to correlate species composition with soil chemical and physical parameters were unsuccessful apart from a pH effect on cyanobacterial distribution. Overall composition of the soil algal community in the Catavi?a region is distinct from other desert sites we have studies, although some cosmopolitan desert soil taxa were present.     

New synonymy and new species of American bark beetles (Coleoptera: Scolytidae), Part VII

New synonymy of American Scolytidae is proposed as follows: Coccotrypes cyperi (Beeson) ( = Thamnurgides indicus Eggers), Pityophthorus attenuatus Blackman ( = Pityophthorus pusillus Wood), Pityophthorus digestus LeConte ( = Pityophthorus aplanatus Schedl), Pseudohylesinus sericeus (Mannerheim) ( = Pseudohylesinus yasamatsui Nobuchi), Xyleborus mutabilis Schedl ( = Xyleborus meridensis Wood). New names are proposed to replace junior homonyms as follows: Pityophthorus indigus for Pityophthorus indigens Wood, 1977 (nec Wood 1976), and Xyloborus devexulus for Xyleborus devexus Wood, 1977 (nec Schedl, 1977). The following species are named as new to science: Conophthorus echinatae (Missouri), Lymantor alaskanus (Alaska), Pityophthorus delicatus (Mexico), P. rubidus (Arizona and Mexico), P. vesculus (Panama), Scolytodes comitabilis, S. crinalis, S. crinitus, S. decorus, S. genialis, S. habilis, S. libidus, S. perpussilus, S. semipunctatus (Venezuela).     

Nerve-mediated action of forskolin on guinea pig ileal mucosa

Summary The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes.Acknowledgment. The authors thank E. Martens, S. Bowen for technical assistance and N. Schaad for secretarial assistance. This work was supported by National Institutes of Health Grants, F32-AM07301, K-104-AM1004, RO1-AM29699, RO1-AM26742 and an Eloise Gerry Fellowship.