Early Ordovician bathyurid province lithofacies, biofacies, and correlations -their relationship to a proto-Atlantic Ocean

The Early Ordovician bathyurid faunal province includes North America, Greenland, Spitsbergen, Scotland, and western Ireland and Norway. Dominant provincial lithofacies and biofacies include a Dolomite Suite with molluscan-stromatolite fossil content rimmed by Limestone Belts with dominantly trilobite-brachiopod faunas on a platform. Shale Belt rocks bearing graptolites, deposited on the platform slopes, rim the Limestone Belts. Volcanic rock-rich terrain partly borders the Shale Belts. Correlation between the lithofacies indicates that change from an expansion to contraction phase of a proto-Atlantic coincided with uplift of the carbonate platform and with tectonic activity in the Atlantic volcanic rock rich terrain. Brachiopods replaced trilobites as dominant faunal elements in more shallow platform waters at the same time. High trilobite diversity remained in deeper waters near platform margins. The changes took place in Earliest Mohawk-ian (Latest Arenig-Earliest Llanvirn).     

Effects of rubidium, potassium and gibberellic acid on plant growth

Growth retardation, measured as internode shortening, was observedin bean and tomato plants when grown in culture solutions towhich Rb had been added. The Rb effect was more pronounced inthe presence of low (0.5 meq/liter) K than high (8 meq/liter)K. Gibberellic acid, added to the solutions, ameliorated thegrowth retardation due to Rb. Epinastic symptoms similar tothose observed with auxin treatment also appeared on the tomatoplants treated with Rb. (Received October 2, 1968; )     

Inherited changes in enzyme patterns within parthenogenetic clones of Aphis fabae

An account is given of changes in esterase enzyme patterns occurring in Aphis fabae populations breeding parthenogenetically.     

HL-A Inhibiting Activity in Human Seminal Plasma

THE HL-A antigens of man have been described on a number of somatic (diploid) cells¹ and demonstrated on spermatozoa, suggesting an expression of the haploid genome on spermatozoan membrane². Soluble HL-A antigens, HL-A2, HL-A7 and 7b, have been reported in serum^3,4. We have now found in human seminal plasma substances that inhibit specific anti-HL-A antibodies. This has important biological and clinical implications, especially for the characterization of HL-A antigens and for the induction of specific tolerance.     

Survival in wild-living mice*

The survival of a mouse in the wild depends on its reaction to the environment (food, climate, social conditions, cover, disease and predation), and this depends on the condition or ‘vigour’ of the animal itself. In general an animal increases in vigour until adulthood, and then begins to decrease, in House mice, at an age of approximately 100 days. These changes can be described as ageing; they lead to the characteristic U-shaped mortality curves deduced from life-tables in a wide variety of mammalian species. Another factor that has to be taken into consideration is genotype, since animals of different genotype may respond differently to environmental stresses. A large number of deaths in wild-living House mouse populations in Britain are temperature-dependent. Animals may respond to cold either physiologically or behaviourally, but it is possible to distinguish between winter survivors and non-survivors with a fair degree of accuracy on the basis of physiological measurements made in the autumn (i.e. before the time of environmental stress). Nevertheless, any general survival model must incorporate environmental, ontogenetic, and genetic factors and their interactions. A simple model is proposed. Animals are not always struggling for existence. They spend most of their time doing nothing in particular. But when they do begin, they spend the greater part of their lives eating (Charles Elton).     

Life History AND BIOECONOMY OF THE House Mouse

1. More is known about the western European house mouse, Mus (musculus) domesticus than any other non-human mammal. If laboratory and field information is combined, an extremely valuable understanding of the species' bioeconomy could be obtained. 2. The seven stages of mouse life-history are surveyed (up to birth, nest life, sex life, social structure, population statics and stability, senescence, and death), and the interactions between the changing phenotype and the environment are described. 3. These interactions can be used to build up a model of the opportunities and compromises which result in the fitness of individual mice. It is not yet possible to quantify such a model, but this should in principle be achievable.     

INTER-YEAR CONTRAST IN NUMBERS AND ANNUAL PRODUCTION OF THE CEPHALASPIDEAN OPISTHOBRANCH RETUSA OBTUSA (MONTAGU) AND THE POSSIBLE INFLUENCE OF WIND-SPEED

Retusa obtusa was far more abundant throughout August 1986-July1987 than in all 12 corresponding months of April 1992-March1993. The greatest difference was when the highest of all counts(3232 m^-2) in May 1987 was 18-times that in May 1992. The leastdifference was a 2.4-fold discrepancy between the two Septembercounts. Mean monthly counts for the 2 periods were 781.4 m^-2(1986-87) and 123.6 (1992-93): a difference of 6.3-times. Biomasssimilarly differed between the 2 periods by factors between2.5 (July) and 12 (March), with a 5.3-fold difference betweenmean monthly biomass values. Annual production was accordinglyestimated as 618.3 (1986-87) and 152.4 (1992-93) mg AFDW m^-2y^-1; so differing by a factor of 4. Yet, in both these 1-yearperiods of observation, the general pattern of annual changewas the same, with settlement in February-May, growth from springto winter, most spawning in December-March and death of adultsat about 1 year in April-May. It is likely that the winter-springperiod of early development in benthic eggs followed by pelagicdispersal, and then settlement in February -May, is a periodof especial vulnerability. In particular, it seems likely thatduring January-May, markedly higher wind-speeds in 1992 thanin 1987 might have contributed to the huge difference in numbersof recruits (Received 2 February 1994; accepted 18 March 1994)