NECTAR PRODUCTION,COMPOSITION, ENERGETICS AND POLLINATOR ATTRACTIVENESS IN SPRING FLOWERS OF WESTERN NEW YORK

High Performance Liquid Chromatography (HPLC) was used to determine specific sugar ratios (fructose, glucose and sucrose) in nectars of nine families of flowering plants. All nectars contained all three sugars with the exception of that of Asclepias. Asclepias nectar was nearly a pure sucrose solution. Sucrose/hexose ratio was correlated with flower morphology, with tubular flowers having more sucrose and open flowers having more hexose. Open flowers contained nectar whose concentration was more affected by relative humidity than tubular flowers. Available nectar in unbagged flowers was found in volumes of 0.1 to 5 μl (17.5 to 68.2% sugar). Total sugar available per blossom amounted to 0.07 to 3.54 mg. We note that care must be taken in converting % concentration to mg sugar. Energetic yield was not as variable as the other measures and ranged from 0.72 to 3.58 cal/μl. Total daily nectar production was measured in five families and 24-hr sugar production varied from 0.64 to 5.52 mg per flower. Insect nectar feeders frequently searched many blossoms with little or no reward, but were rewarded sufficiently at rare “lucky hit” blossoms which contained relatively large nectar rewards. Insect pollinators did not seek nectars of specific sucrose-hexose ratios, but instead took nectar where caloric reward and accessibility made it most profitable.     

Soilborne Plant Diseases Caused by Pythium spp.: Ecology,Epidemiology, and Prospects for Biological Control

Soilborne root diseases caused by plant pathogenic Pythium species cause serious losses in a number of agricultural production systems, which has led to a considerable effort devoted to the development of biological agents for disease control. In this article we review information on the ecology and biological control of these pathogens with the premise that a clear understanding of the ecology of the pathogen will assist in the development of efficacious biocontrol agents. The lifecycles of the pathogens and etiology of host infection also are reviewed, as are epidemiological concepts of inoculum-disease relationships and the influence of environmental factors on pathogen aggressiveness and host susceptibility. A number of fungal and bacterial biocontrol agents are discussed and parallels between their ecology and that of the target pathogens highlighted. The mechanisms by which these microbial agents suppress diseases caused by Pythium spp., such as interference with pathogen survival, disruption of the process of plant infection, and induced host resistance, are evaluated. The possibilities for enhancement of efficacy of specific biological control agents by genetic manipulation or deployment tactics are discussed, as are conceptual suggestions for consideration when developing screening programs for antagonists.     

Mutational analysis of genes determining antagonism of Alcaligenes sp. strain MFA1 against the phytopathogenic fungus Fusarium oxysporum.

Alcaligenes sp. strain MFA1 inhibits microconidial germination and germination-tube elongation of Fusarium oxysporum f.sp. dianthi and reduces the severity of fusarium wilt of carnation, presumably as a result of its production of a siderophore (G.Y. Yuen and M.N. Schroth. 1986. Phytopathology, 76:171-176). Derivative strains of MFA1, deficient in antagonism against F. oxysporum and in iron-limited growth, were obtained by Tn5 mutagenesis. The presence of a single Tn5 insertion in the genomic DNA of each derivative strain was detected by Southern analysis. Marker-exchange mutagenesis of strain MFA1 with DNA fragments, containing Tn5 and flanking sequences cloned from representative mutants, confirmed the association of single Tn5 insertions with the loss of antifungal activity and iron-independent growth of MFA1. These results are consistent with the involvement of siderophore biosynthesis by MFA1 in the inhibition of F. oxysporum.     

Proposed follow up programme after curative resection for lower third oesophageal cancer

Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy.