Abstract: A gas release device that includes a reservoir of pressurised gas and a passageway from said reservoir to an outlet. There is an elastic gas permeable membrane in the passageway that allows gas release only via the membrane. A gas impermeable member is provided in the passageway that includes an interface positioned to contact said gas permeable membrane. Displacement of the gas permeable membrane is responsive to the pressure of the gas in the reservoir such that there is a greater interfacial contact between the gas impermeable member and the gas permeable membrane at a higher gas pressure than at lower pressure to thereby vary the exposed cross sectional area of the permeable membrane available to the flow in an inverse relationship to pressure.

Abstract: A gas release device that includes a reservoir of pressurised gas and a passageway from said reservoir to an outlet. There is an elastic gas permeable membrane in the passageway that allows gas release only via the membrane. A gas impermeable member is provided in the passageway that includes an interface positioned to contact said gas permeable membrane. Displacement of the gas permeable membrane is responsive to the pressure of the gas in the reservoir such that there is a greater interfacial contact between the gas impermeable member and the gas permeable membrane at a higher gas pressure than at lower pressure to thereby vary the exposed cross sectional area of the permeable membrane available to the flow in an inverse relationship to pressure.

Abstract: A DNA segment from the upstream untranscribed region of a maize ubiquitin gene is disclosed. This ubiquitin promoter region, which comprises heat shock consensus elements, initiates and regulates the transcription of genes placed under its control. Recombinant DNA molecules are also described in which a ubiquitin promoter is combined with a plant expressible structural gene for regulated expression of the structral gene and for regulated control of expression when stressed with clevated temperatures. Such recombinant DNA molecules are introduced into plant tissue so that the promoter/stuctural gene combination is expressed.

Abstract: A method of inducibly enhancing the constitutive expression of a DNA sequence of interest is described in which plant cells are transformed with a DNA sequence of interest that is operably joined to a plant ubiquitin regulatory region comprised of a heat shock element, a promoter, a transcription start site, an intron and a translation start site, When monocot or dicot plant cells are subjected to permissive heat shock temperatures, the level of expression of the DNA sequence of interest is enhanced.

Abstract: A method of inducibly enhancing the constitutive expression of a DNA sequence of interest is described in which plant cells are transformed with a DNA sequence of interest that is operably joined to a plant ubiquitin regulatory region comprised of a heat shock element, a promoter, a transcription start site, an intron, and a translation start site. When monocot or dicot plant cells are subjected to permissive heat shock temperatures, the level of expression of the DNA sequence of interest is enhanced.

Abstract: A DNA segment from the upstream untranscribed region of a maize ubiquitin gene is disclosed. This ubiquitin promoter region, which comprises heat shock consensus elements, initiates and regulates the transcription of genes placed under its control. Recombinant DNA molecules are also described in which a ubiquitin promoter is combined with a plant expressible structural gene for regulated expression of the structural gene and for regulated control of expression when stressed with elevated temperatures. Such recombinant DNA molecules are introduced into plant tissue so that the promoter/structural gene combination is expressed.