Flow cytometry (FCM) is now becoming a routine tool for the enumeration and optical characterization of bacteria in marine environments. We investigated the effects of sample fixation and storage upon flow cytometric determination of marine bacteria. Fixed and unfixed seawater samples were analyzed by FCM immediately aboard ship and/or later in the laboratory, and the appearances of the fluores...

The rarity of symbiotic nitrogen-fixing trees in higher-latitude compared to lower-latitude forests is paradoxical because higher-latitude soils are relatively N poor. Using national-scale forest inventories from the United States and Mexico, we show that the latitudinal abundance distribution of N-fixing trees (more than 10 times less abundant poleward of 35 degrees N) coincides with a latitud...

Rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. This symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. Rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. A ...

Examination of root systems and adhering soil associated with unusually green corn plants from nitrogen-deficient areas in fields has revealed higher acetylene-reducing activities than comparable root systems of chlorotic plants that appeared to be nitrogen deficient. From the root systems with acetylene-reducing activity, N(2)-fixing Enterobacter cloacae were isolated. Pure cultures of the org...

BACKGROUND During the early postoperative period, the fixation of a hamstring graft to the bone tunnel is the primary factor in limiting rehabilitation. HYPOTHESIS The initial fixation strength of a double cross pin fixation technique is comparable with the biodegradable interference screw fixation technique. STUDY DESIGN Experimental laboratory study. METHODS The authors examined the ini...

Symbioses between plants and nitrogen (N) fixing bacteria are ecologically and economically important interactions with complex evolution and ecology. Theoretical and experimental studies suggest that host specificity and environmental variation are important determinants of both evolutionary and ecological patterns in such interactions, but detailed descriptions of these parameters in natural ...

among the treatments from the water agar plates. Percentages did increase substantially, however, on N-free White's medium where p e r c e n t a g e s o f n o d u l a t i o n w e r e approximately two times higher for intact roots (59-61) when compared with excised roots (28-30). Nodules formed on roots in each experiment were tested for nitrogen fixation using the method of Koch and Evans (4)....

Agave tequilana Weber var. 'Azul' is grown for the production of tequila, inulin and syrup. Diverse bacteria inhabit plant tissues and play a crucial role for plant health and growth. In this study culturable endophytic bacteria were extracted from leaf bases of 100 healthy Agave tequilana plants. In plant tissue bacteria occurred at mean population densities of 3 million CFU/g of fresh plant t...

The exploitation of the soybe an [Glycine max (L.) Merr.] -Bradyrhizobium japonicum symbiosis in varied environments requires an understanding of factors that may affect fixed and soil N assimilation. Temperature affects both soybean maturity and N requirement, and soil N availability. Five soybean varieties belonging to four maturity groups (00, IV, VI, and VIII) and their respective nonnodula...