Search

Amplitude analysis of reflection seismic data reveals the presence of highly variable bed conditions under the main sticky spot and adjacent regions of the Kamb Ice Stream (KIS—formerly ice stream C). The sticky spot, which is a zone of bed that imparts high basal resistance to ice flow, is situated on a local topographic high composed of consolidated sediments or sedimentary rock. Any meltwater draining from upglacier along the base of the ice is routed around the sticky spot. The ice over the sticky spot includes, in at least some places, a seismically detectable basal layer containing a low concentration of debris, which locally thickens to 40 m over a topographic low in the bed. The ice-contact basal material ranges from dilated and highly porous to more-compacted and stiff, and perhaps locally frozen. The softer material is preferentially in topographic lows, but there is not a one-to-one correspondence between basal character and basal topography. We speculate that the 40-m-thick frozen-on debris layer formed by glaciohydraulic supercooling of lake-drainage events along a basal channel during the former, active phase of the ice stream. We also speculate that loss of lubricating water, perhaps from piracy upstream, contributed to the slowdown of the ice stream, with drag from the sticky spot playing an important role, and with the basal heterogeneity greatly increasing after the slowdown of the ice stream.

Selective cloning of the cDNA coding for a weak neurotoxin (WTX) from cobra N. kaouthia including the 5'- and 3'-non-translated regions (NTR) is described. The known amino acid sequence of WTX was used together with the nucleotide sequence of a weak neurotoxin NNAM2 from cobra Naja atra, to design WTX-specific primers for direct amplification of an internal WTX cDNA fragment by RT- PCR. The sequence of the complete WTX cDNA was determined in sequencing runs on internal PCR products, cloned 3'- and 5'-RACE-fragments and several full-length cDNA clones. The cDNA coding sequence is in excellent agreement with the previously determined WTX amino acid sequence, has a high homology with other known weak toxin cDNAs, whereas even higher homology (up to 96%) with several classes of 3-finger toxins was detected in the 59 bp 3'-NTR consensus sequence. A possible function of the highly conserved nucleotide sequence elements is discussed.

Using 6mer and 12mer phage peptide libraries three unique phage clones were identified which specifically bind to a monoclonal anti-FITC antibody, B13-DE1. The two 6mer and one 12mer peptide insert sequences are clearly related to each other and contain a high proportion of hydrophobic amino acids. The peptides are bound by the antibody combining site of B13-DE1 probably in a similar manner to FITC and represent therefore true peptidic mimics of the fluorescein hapten. No reactivity of the peptides could be demonstrated with another monoclonal anti-fluorescein antibody or with polyclonal anti-fluorescein antibodies. Immunization of mice with the peptides resulted in the production of antibodies cross-reacting with all peptides but not with fluorescein. The results show that phage peptide libraries can be used to isolate mimotope peptides which can mimic low molecular weight structures seen by a specific antibody and probably other recognition molecules. Copyright © 1999 John Wiley & Sons, Ltd.

This report compares the effectiveness of various compounds with progestogenic activity in a series of tests involving the chick the rat the mouse and the rabbit. The inhibition of oviduct growth stimulation of decidual growth and the Clauberg test were used for measurement of activity of 17-alpha-hydroxyprogesterone 17-alpha-hydroxyprogesterone caproate 11 dehydroprogesterone 17-alpha-ethyl-19-nortestosterone and 17-alpha-ethinyl-19-nortestosterone. In the chick oviduct test 16-day-old female white Leghorns were treated for 7 days and sacrificed on Day 8. The entire genital tract from the infundibulum to the cloaca was included in the oviduct weight. Injection of stilbestrol alone gave a typical sigmoid dose-response curve with a sharp increase in weight from 13 mg % of body weight at .05 mg daily to 1048 mg percent at 1 mg daily. A standard dose of 1 mg a day of stilbestrol was then selected for further experiments. Progesterone produced a marked inhibition of the stilbestrol-stimulated oviduct in the chick particularly when dissolved in oil; all the compounds tested showed some inhibition ability. Adult female Holtzman rats were castrated treated with 1 mg of estrone for 4 days followed by 9 days of progesterone or one of the test compounds. The uterus was exposed on Day 5 of test-drug treatment and 1 mg of histamine dihydrochloride injected into the left horn. A marked deciduoma was apparent with .5 mg progesterone daily. The degree of deciduomatogenesis was evaluated by comparing the percentage of increase of the histamine-treated horn with the other. At .2-2 mg daily progesterone gave a good dose response curve up to 400% increase when suspended in oil. Suspension of the hormone in saline with "Tween 80" decreased activity by 50%. 11-dehydroprogesterone was twice as effective as progesterone. The other compounds gave little or no response even in large doses. In mice similar tests showed the decidual response in the mouse is a more sensitive index of progestone-like activity than in the rat. No significant activity was observed with any of the test compounds except 17-alpha-ethyl-19-norethisterone. The Clauberg test in rabbits gave similar results to previously reported work. 11-dehydroprogesterone was effective at .15 mg twice the activity of progesterone. It had only a third the activity of progesterone in the Hooker-Forbes test. Both the 17-alpha-ethyl-19-nortestosterone and the 17-alpha-ethinyl-19-nortestosterone appeared to be superior to progesterone in Clauberg and chick-oviduct tests; the ethynyl derivative was superior to the ethyl derviative in the chick test; only 11-dehydroprogesterone mirrored all the activities of progesterone and was consistently superior to the hormone.