Hormones gaseous

Despite the potent influence of ethylene on the whole plant development, most often it has been recognized as a fruit-ripening and senescence-associated hormone. With respect to the gaseous nature of this hormone, the knowledge about ethylene sensitivity of fruit and flower is necessary to predict the effects of their mixed storage and transport and the usefulness of anti-ethylene treatments. Such commercial implications of ethylene have made it a topic of investigation for decades. 

There are many examples of second-order reactions for example, associations, addition reactions, etc. The decomposition of gaseous nitrogen dioxide (2NO2 2NO + O2) follows the rate law, -d[N02]/dr = fc[N02]. The binding of a hormone to a receptor protein is also second-order. 

Farmer, 2001). Even nectar production may be effected by such hormones (Heil et al, 2001). The gaseous hormone ethylene plays an important role in plant development, but also in defense (Mattoo and Suttle, 1991). Upon perception of a pathogen, plants show enhanced ethylene production, which has been shown to be involved in the induction of defense reactions (Boiler, 1991). Wild tobacco plants engineered with an Arabidopsis sp. ethylene-insensitive gene do not show typical leaf development arrestment in the presence of leaves of other tobacco plants, demonstrating the importance of ethylene in plant development (Knoester et al.,... 

Nitric oxide is a reactive, paramagnetic gaseous free radical which is formed in the human body and in other organisms by an enzymatic oxidation of L-arginine (Eq. 18-65). Since about 1980, NO has been recognized as a hormone with a broad range of effects... 

The production of ethylene in fruit tissue and in small amounts in leaves may justify its consideration as a hormone, functioning in the gaseous state, Cherimoyas and some varieties of pear produce 1000 times the effective physiological concentration. Ethylene formation is closely linked to oxidation and may be centered in the mitochondria. Its effects are to promote cell-wall softening, starch hydrolysis, and organic add disappearance in fruits—the syndrome known as ripening. Ethylene also decreases the geotiopic responses of stems and petioles. 

Synthesis of ethylene, a gaseous plant hormone involved in fruit ripening and flower senescence. 

Aeration of suspension cultures grown in bioreactors needs to be optimized with respect to dissolved oxygen and carbon dioxide levels. High aeration rates may lead to excessive (toxic) concentrations of dissolved oxygen, increased shear forces, and subcritical levels of key volatiles such as gaseous hormones (ethylene) and carbon dioxide (62). Carbon dioxide enrichment of the aeration mixture increased biomass yields 63,64). Van Gulik (65) has recently reviewed this subject in detail. 

Fetal membranes include the amniotic fluid, umbilical cord, and placenta. The placenta is made up of the inner amnion layer and outer chorion layer. The placental tissues provide homeostasis and exchange of important nutrients, electrolytes, and gaseous products. They also produce important hormones for the development of the growing fetus. The placenta also provides protection for the fetus by producing maternal antibodies and physical protection by surrounding the fetus in amniotic fluid. 

The gaseous plant hormone ethylene is biosynthesized in plant tissue by the following sequence methionine- SAM ACC ethylene [33]. In plant tissues ACC synthase which catalyzes the conversion of SAM to ACC and MTA, is generally the rate-controlling enzyme in the pathway. Soon after Adams and Yang [2] elucidated that ACC derived from SAM served as the immediate precursor of ethylene, Boiler et al. [5] and Yu et al. [37] demonstrated ACC synthase (EC 4.4.1.14) activity from tomato fruit. As predicted from in vivo study, this enzyme requires pyridoxal phosphate. 

Effects of Endogenous Wound-Induced Gaseous Hormones and Ethylene Inhibitors on Polysome Formation... 

Two short reports concerning another mononuclear iron (ferrous) centre, 1-aminocyclopropane- 1-carboxylic acid oxidase, abbreviated ACCO, have been presented. This enzyme catalyses the last step in the synthesis of ethylene, a gaseous hormone involved in ripening of plants. One paper deals with spectroscopic techniques including near infrared (NIR) and circular or magnetic circular dichroism applied to the ferrous active site. The other is on preliminary ENDOR data probing the ligation and structure of this site in the ferric state. ... 

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