The RCE: a Riparian, Channel, and Environmental Inventory for small streams in the agricultural landscape

1. The Riparian, Channel and Environmental (RCE) Inventory has been developed to assess the physical and biological condition of small streams in the lowland, agricultural landscape. It consists of sixteen characteristics which define the structure of the riparian zone, stream channel morphology, and the biological condition in both habitats. 2. The inventory is based on the view that in landscapes where non-point source pollution and agriculture dominate, the environmental condition of small streams can be assessed by an appraisal of the physical condition of the riparian zone and stream channel. It is assumed that disturbance of this physical structure is a major cause for reduction of stream biological structure and function. This assumption is supported by a case study using fifteen Italian stream locations in which the RCE was found to be positively correlated to the benthic macroinvertebrate community as measured by the Extended Biotic Index (r = 0.80, P < 0.001) and the Shannon Diversity Index (r = 0.73; P < 0.001). 3. The inventory is designed for quick use to cover a large number of streams in a short period of time. When used it generates a numerical score which can be used to compare the physical and biological condition between different streams within a region. The numerical score is divided into five, colour-coded classes to facilitate use in streammonitoring programmes and to allow comparison with biological indices.     

The integron In1 in plasmid R46 includes two copies of the oxa2 gene cassette.

The sequence of the insert region of the integron In1 found in the IncN plasmid R46 was completed. The insert region is 2929 bases long and includes four gene cassettes, two of which are identical copies of the oxa2 gene cassette flanking an aadA1 cassette. The fourth cassette encodes an open reading frame orfD. From comparison of these data with published maps and sequences it is argued that the integrons found in the IncN plasmids pCU1 and R1767 and in the transposon Tn2410 are closely related to In1 from R46. Both site-specific gene insertion and recA-dependent recombination are likely to have contributed to the evolution of these integrons.     

Monoclonal antibodies against the ruminal bacterium Selenomonas ruminantium.

Monoclonal antibodies were raised against whole cells of two different strains of Selenomonas ruminantium and tested for specificity and sensitivity in immunofluorescence and enzyme-linked immunosorbent assay procedures. Species-specific and strain-specific antibodies were identified, and reactive antigens were demonstrated in solubilized cell wall extracts of S. ruminantium. A monoclonal antibody-based solid-phase immunoassay was established to quantify S. ruminantium in cultures or samples from the rumen, and this had a sensitivity of 0.01 to 0.02% from 10(7) cells. For at least one strain, the extent of antibody reaction varied depending upon the stage of bacterial growth. Antigen characterization by immunoblotting shows that monoclonal antibodies raised against two different strains of S. ruminantium reacted with the same antigen on each strain. For one strain, an additional antigen reacted with both monoclonal antibodies. In the appropriate assay, these monoclonal antibodies may have advantages over gene probes, both in speed and sensitivity, for bacterial quantification studies.     

Historical and Life History Factors in the Biogeography of Mayflies

SYNOPSIS. Cladistic analysis of mayflies suggests that dispersalwas very asymmetrical after the new land connection betweenNorth and South America. Twenty-one genera apparently movedfrom South to North and Central America, but there is good evidencefor only one North American genus moving into the south. Testablepredictions are possible once the boreal (Laurasian) or austral(Gondwanian) designations are made. For example, Paracloeodes,a genus of austral origin, was predicted to be found in SouthAmerica, and in North America in warm rivers north and eastof its known distribution. These predictions have been confirmed.Other characteristics of tropical mayflies, such as length oflarval period and emergence and mating patterns, may be usedto predict habitats and characteristics of present North Americangenera. Merger events and consequent dispersal of organismshave profound influences on distributional patterns, and fromsuch information, biologically useful generalities can be made.     

Enzyme histochemistry of the mesocoxal muscles of Periplaneta americana

Histochemical techniques have been employed to characterize enzymatic activity in the mesocoxal muscles of the cockroach, Periplaneta americana. Through our studies of the enzymes myosin-ATPase, NADH reductase, succinic dehydrogenase (SDH), and lactic dehydrogenase (LDH), we were able to classify fibers within these muscles according to criteria established for muscle fibers of vertebrates. Many of the mesocoxal muscles possess two different and distinct populations of fibers, whereas the remaining muscles are homogeneous with respect to their constituent fibers. The data presented here indicate biochemical heterogeneity for muscles of differing structural and functional features and possible neurotrophic influences upon oxidative enzymes and myosin-ATPase isozymes.     

Late Devonian benthic marine communities of the central Appalachian Allegheny Front

Four benthic marine communities occur in the clastic facies of the prograding Upper Frasnian-Lower Famennian (Upper Devonian) Foreknobs Formation in the Central Appalachians along the Allegheny Front in Maryland, West Virginia, and Virginia. Deep-water, rapidly prograding environments were inhabited by the Ambocoelia-Chonetes Community, dominated by an epifauna of unattached brachiopods. Offshore bar environments were inhabited by the Cyrtospirifer-Camarotoechia Community, exhibiting adaptations to shallow-water, high-energy conditions and probably lowered salinities. Shallow-water, sublittoral environments were inhabited by the Atrypa-Cypricardella Community, a community in which existed a variety of life habitats and a diverse epifaunal and infaunal association of brachiopods and bivalve molluscs. The Leptodesma-Tylothyris Community flourished in nearshore bar-protected environments in the southern region of the study area, whereas in the north the Cyrtospirifer-Camarotoechia Community inhabited nearshore environments in conjunction with the onshore development of a large fluviodeltaic system.     

Fatty Acid and Chlorophyll Levels of Coastal Bermudagrass during the Day and during Maturation

Lipids were extracted from fresh, field-grown coastal bermudagrass (Cynodon dactylon (L.) Pers.) and the fatty acids determined by gas chromatography. Total fatty acid levels (dry weight basis) increased during the day and reached a single maximum at sunset in 2-week-old grass; whereas, in older grass, the fluctuations in fatty acid levels showed two maxima. The first maximum occurred 4 h after sunrise and the second maximum occurred at sunset. Total fatty acid levels, based on dry weight, decreased during the first 6 weeks of growth and changed very little after an additional 4 weeks' growth in bermudagrass leaf blades. Chlorophyll levels (dry weight basis) continuously decreased during the entire growth period (10 weeks). Chlorophyll alb ratios increased at sunset in 2- and 6-week-old grass, but this ratio did not change during the day in subsequent growth stages. The results of these experiments show that stages of maturity affected fatty acid fluctuations during the day as well as total fatty acid and chlorophyll levels in Coastal bermudagrass leaf blades. Chlorophyll alb ratios varied independently of fatty acid levels.