Changes in Activity of Choline Acetylase in Central Nervous System of Rat after Intraventricular Administration of Noradrenaline

APPLICATION of strychnine or d-tubocurarine to the exposed cerebral cortex leads after a few minutes to abnormality in somatosensory evoked potentials^1,2. This consists of a surface negative wave (peak latency, 21–23 ms) which attains an amplitude five to twenty times greater than that of the normal evoked potentials and probably reflects excessive depolarization of the apical dendrites of pyramidal neurones. We wish to report the blocking of this effect by prior application of eserine to the cortex.     

Crystal Structure of the C-Terminal Tetrapeptide of Oxytocin

WE have determined the crystal structure of the protected, C-terminal tetrapeptide of oxytocin S-benzyl-L-cysteinyl-L-prolyl-L-leucyl-glycine amide as well as of its virtually isomorphous seleno-analogue. The crystal structure analyses of these two peptides were undertaken because of our interest in the conformation of the tetrapeptide in isolation as well as when attached to the ring in the complete oxytocin molecule. The seleno-analogue provided an opportunity to compare sulphur and selenium stereochemistry.     

Aldolase Levels in Wild-Type and Mutant Euglena gracilis

SYNOPSIS. Wild-type Euglena gracilis var. baciliaris , strains B and Z, synthesize 2 distinct fructose-1,6-diphosphate aldolases. Amounts of the 2 activities depend upon conditions of growth. The class I enzyme, with activity similar to that found in various photosynthetic tissues, is formed during regreening of dark-grown cultures incubated in the light. Very low activity of the class I enzyme is also found in mutant strains W₃BUL and W₈BHL, both of which apparently lack plastid DNA. The significance of these findings is discussed.     

Bryophyte and lichen diversity: A comparative study

Abstract We describe the regional species richness, variation in species richness and species turnover of bryophytes and lichens from 36 sites in lowland forests of southeastern Australia. The analyses subdivided the two major taxa into their constituent sub-groups: mosses, liverworts, and crustose, fruticose and foliose lichens. They also explored correlations between selected environmental variables and patterns of diversity. On a regional scale, there were 77 species of bryophytes and 69 species of lichens, giving a total of approximately one-third of the total number of vascular plant species in the region. Mean species richness was higher for lichens than bryophytes. Also, the two taxa were negatively correlated because lichens favoured dry sites and bryophytes favoured moist ones. Species turnover was greater for bryophytes than lichens, largely due to the distribution of liverwort species. Foliose lichens showed higher levels of turnover than crustose lichens. Multiple regression and canonical correspondence analysis showed that both taxa and all sub-groups responded to the same three variables: vascular plant cover, time since last fire and topographic position. Other variables, including time since logging and intensity of logging, explained little variation in bryophyte or lichen diversity. The data suggest that the strategies for the conservation of bryophyte and lichen biodiversity will be different, to reflect the different patterns of species richness and species turnover.     

Pollination of endangered Cuban cycad Microcycas calocoma (Miq.) A.DC.

Observations indicate that natural regeneration in the field of the cycad Microcycas calocoma (Miq.) A.DC. is extremely low, and has been so since early this century. It appears that populations of its insect pollinator are practically extinct, but some pollinator activity appears to be present in the largest population of Microcycas. Recommendations for identification and captive breeding of die pollinator are suggested as a complementary conservation strategy to a Microcycas propagation programme already established at the Cuban National Botanical Garden.     

Violence in War and Peace: An Anthology

Violence in War and Peace: An Anthology . Nancy Scheper-Hughes and Philippe Bourgois, eds. Malden, MA: Blackwell Publishers, 2004. 496 pp.     

Hunting mode and success of African Peregrines Falco peregrinus minor,does nesting habitat quality affect foraging efficiency?

Peregrine Falcon Falco peregrmus hunting behaviour was studied at nest-sites in three areas of South Africa over eight years. In Africa, resident Peregrines are mostly restricted to high cliffs, possibly because these structures provide optimal conditions for hunting. This hypothesis is examined in terms of the influence of nest-site quality, particularly cliff height, on foraging efficiency. Foraging mode varied considerably between sites, and males foraged more actively than females but there was little variation in the design of hunts between sexes, seasons or study areas. Individually, Peregrines spent 30–50% of the day on or near the nest cliff. On average, about 0.5 hunts were recorded per hour of observation. Foraging mode was not correlated with cliff height or elevation above the surrounding terrain, but Peregrine pairs occupying higher cliffs achieved greater hunting success rates. Most hunts were initiated from elevated perches on the nest cliff, and perch hunts were more successful than strikes made from the air. Success was highest in strikes at doves and small passerines, and over habitats with moderate cover. The height difference between Peregrine and prey at the start of a hunt positively and significantly affected hunting success. Overall, Peregrines were relatively sedentary and made extensive use of the nesting habitat as a foraging area. High nest cliffs contributed to foraging success by providing perch-hunting falcons with an effective height advantage over their prey.