Molecular evolution of herbicide resistance to phytoene desaturase inhibitors in \u3ci\u3eHydrilla verticillata\u3c/i\u3e and its potential use to generate herbicide-resistant crops

Hydrilla [Hydrilla verticillata (Lf) Royle] is one of the most serious invasive aquatic weed problems in the USA. This plant possesses numerous mechanisms of vegetative reproduction that enable it to spread very rapidly. Management of this weed has been achieved by the systemic treatment of water bodies with the herbicide fluridone. At least three dioecious fluridone-resistant biotypes of hydrilla with two- to fivefold higher resistance to the herbicide than the wild-type have been identified. Resistance is the result of one of three independent somatic mutations at the arginine 304 codon of the gene encoding phytoene desaturase, the molecular target site of fluridone. The specific activities of the three purified phytoene desaturase variants are similar to the wild-type enzyme. The appearance of these herbicideresistant biotypes may jeopardize the ability to control the spread of this non-indigenous species to other water bodies in the southern USA. The objective of this paper is to provide general information about the biology and physiology of this aquatic weed in relation to its recent development of resistance to the herbicide fluridone, and to discuss how this discovery might lead to a new generation of herbicide-resistant crops

Molecular evolution of herbicide resistance to phytoene desaturase inhibitors in \u3ci\u3eHydrilla verticillata\u3c/i\u3e and its potential use to generate herbicide-resistant crops

Hydrilla [Hydrilla verticillata (Lf) Royle] is one of the most serious invasive aquatic weed problems in the USA. This plant possesses numerous mechanisms of vegetative reproduction that enable it to spread very rapidly. Management of this weed has been achieved by the systemic treatment of water bodies with the herbicide fluridone. At least three dioecious fluridone-resistant biotypes of hydrilla with two- to fivefold higher resistance to the herbicide than the wild-type have been identified. Resistance is the result of one of three independent somatic mutations at the arginine 304 codon of the gene encoding phytoene desaturase, the molecular target site of fluridone. The specific activities of the three purified phytoene desaturase variants are similar to the wild-type enzyme. The appearance of these herbicideresistant biotypes may jeopardize the ability to control the spread of this non-indigenous species to other water bodies in the southern USA. The objective of this paper is to provide general information about the biology and physiology of this aquatic weed in relation to its recent development of resistance to the herbicide fluridone, and to discuss how this discovery might lead to a new generation of herbicide-resistant crops

MPEG-4: An object-based multimedia coding standard supporting mobile applications

The ISO MPEG committee, after successful completion of the MPEG-1 and the MPEG-2 standards is currently working on MPEG-4, the third MPEG standard. Originally, MPEG-4 was conceived to be a standard for coding of limited complexity audio-visual scenes at very low bit-rates; however, in July 1994, its scope was expanded to include coding of scenes as a collection of individual audio-visual objects and enabling a range of advanced functionalities not supported by other standards. One of the key functionalities supported by MPEG-4 is robustness in error prone environments. Furthermore, the MPEG-4 standard is being designed to provide solutions for audio coding, video coding, systems multiplex/demultiplex and scene composition in a truly flexible manner. This paper provides an overview of the current status of the MPEG-4 standard. Section 2 provides a brief overview of the status of related ITU-T standards, since they form a starting basis for video and systems part of the MPEG-4 standard. We then present overview of the MPEG-4 in terms of requirements, tests, video, audio and systems. In sections 4, 5 and 6, with focus on mobile multimedia functionality, we provide discuss the respective coding methods of MPEG-4 Visual, Audio and Systems standards. In section 7 we discuss the issue of profiles, and in section 8 the plans for verification tests are presented. Finally, we summarize the current status of MPEG-4, its planned upgrade to a new version, and the plans for MPEG-7, the next MPEG standard following MPEG-4. 1

Methods and apparatus for integrating external applicaitons into an MPEG-4 scene

A method of decoding, composing and rendering a scene. First information is obtained, the first information including a part of a MPEG-4 BIFS scene description stream and at least one coded MPEG-4 media stream. The first information is decoded by invoking a BIFS scene decoder and one or more specific media decoders that are required by the scene. Second information is obtained, the second information including a second part of a BIFS scene description stream that contains a reference to an external application. The second information is decoded by invoking the BIFS scene decoder and an external application decoder. An integrated scene is composed, the integrated scene including one or more decoded MPEG-4 media objects and one or more external application objects specified in the decoded scene descriptions streams. The composed integrated scene is rendered on a display