Use of LOD score technology in mapping quantitative trait loci in plants

The use of LOD score analysis developed on the basis of the maximum likelihood method for establishing genetic linkage between loci determining the manifestation of quantitative traits and molecular markers in plant genetics is examined. Experimental data on the use of this approach for revealing LOD values in higher plants for the example of mapping Brassica rapa L. populations are given.     

Use of interspecific hybridization for increasing buckwheat tolerance to inbreeding

The productivity of inbred buckwheat lines I₁–I₈ with the homostyly gene of Fagopyrum esculentum and Fagopyrum homotropicum is studied. The species F. homotropicum is recommended for use in buckwheat breeding as a donor of homostyly and tolerance to inbreeding depression.     

Paleocirculation of the deep north atlantic: 150,000-year record of benthic foraminifera and oxygen-18

Benthic foraminiferal faunas in a piston core from 3331 meters at 44 degrees N on the Mid-Atlantic Ridge show striking variations in the relative abundance of species. Uvigerina peregrina, which is broadly distributed today in the South Atlantic and in the Pacific in water that has been long isolated from the surface, is absent in the North and Equatorial Atlantic at depths occupied by highly oxygenated North Atlantic deep water. This species dominated the fauna at this site for much of the past 150,000 years. It is suggested that North Atlantic deepwater production was much reduced or eliminated at times of Uvigerina peregrina abundance, as a result of cooling and stratification of the Norwegian Sea surface, coincident with the times of the southward migration of the polar front in the North Atlantic.     

Reweaving the food security safety net: Mediating entitlement and entrepreneurship

The American food system has produced both abundance and food insecurity, with production and consumption dealt with as separate issues. The new approach of community food security (CFS) seeks to re-link production and consumption, with the goal of ensuring both an adequate and accessible food supply in the present and the future. In its focus on consumption, CFS has prioritized the needs of low-income people; in its focus on production, it emphasizes local and regional food systems. These objectives are not necessarily compatible and may even be contradictory. This article describes the approach of community food security and raises some questions about how the movement can meet its goals of simultaneously meeting the food needs of low-income people and developing local food systems. It explores the conceptual and political promise and pitfalls of local, community-based approaches to food security and examines alternative economic strategies such as urban agriculture and community-supported agriculture. It concludes that community food security efforts are important additions to, but not subsitutes for, a nonretractable governmental safety net that protects against food insecurity.     

Crystallographic structure of the octameric histone core of the nucleosome at a resolution of 3.3 A

The structure of the (H2A-H2B-H3-H4)2 histone octamer has been determined by means of x-ray crystallographic techniques at a resolution of 3.3 angstroms. The octamer is a prolate ellipsoid 110 angstroms long and 65 to 70 angstroms in diameter, and its general shape is that of a rugby ball. The size and shape are radically different from those determined in earlier studies. The most striking feature of the histone octamer is its tripartite organization, that is, a central (H3-H4)2 tetramer flanked by two H2A-H2B dimers. The DNA helix, placed around the octamer in a path suggested by the features on the surface of the protein, appears like a spring holding the H2A-H2B dimers at either end of the (H3-H4)2 tetramer.     

Pleistocene Sea Levels, Southeastern Virginia

Detailed study of post-Miocene stratigraphy in southeastern Virginia reveals at least 13 formations which show six Pliocene (?) and Pleistocene cycles of emergence and submergence, with maximum submergent sea levels near +45, +45, +20, +25, +15, and 0 feet, respectively. The newly established stratigraphic framework disproves earlier interpretations of "terrace-stratigraphy" and sea level chronologies.     

Contributions of two types of calcium channels to synaptic transmission and plasticity

In Aplysia sensory and motor neurons in culture, the contributions of the major classes of calcium current can be selectively examined while transmitter release and its modulation are examined. A slowly inactivating, dihydropyridine-sensitive calcium current does not contribute either to normal synaptic transmission or to any of three different forms of plasticity: presynaptic inhibition, homosynaptic depression, and presynaptic facilitation. This current does contribute, however, to a fourth form of plasticity--modulation of transmitter release by tonic depolarization of the sensory neuron. By contrast, a second calcium current, which is rapidly inactivating and dihydropyridine-insensitive, contributes to release elicited by the transient depolarization of an action potential and to the other three forms of plasticity.     

Paleontological Evidence of Varitions in Length of Synodic Month since Late Cambrian

The values of length of synodic month, obtained from tidally controlled periodical growth patterns in mollusks and stromatolites for several geologic periods, indicate that the deceleration rate of the earth's rotation has not been constant. Two breaks in slope, in the Pennsylvanian and Cretaceous, may be related to changes in distribution of continents, oceans, and adjacent shallow seas.     

Genetic polymorphism of initial apple-tree shapes by alleles of genes associated with long shelf life and fruit quality

Features of the analyzed allele distribution in domestic and foreign varieties are revealed on the basis of apple variety and shape polymorphism in alleles of genes associated with shelf life (Md-ACS1 and Md-ACO1) and fruit quality (MD-Exp7). Two allelic states have been revealed for the Md-ACS1 gene. With regard to the foreign selection Fuji and Gala varieties, the Md-ACS1 gene is in a homozygous state. In the examined varieties, the Md-ACO1 gene is represented by two allelic variants, and the MD-Exp7 gene of expansin biosynthesis is represented by three allelic forms. Allele 1 is responsible for a lowered level of expansin synthesis and is identified in wild apple-tree species (Chinese Golden Apple, Tayozhnoye, Caucasian Self-Fruitful).