E. W. YEMM's research while affiliated with University of Bristol and other places

Publications (33)

Article
Carbon dioxide exchanges in the dark and in the light indicate that photosynthetic activity occurs m young leaves of barley seedlings after about 3 hours illumination under favourable conditions. Activity increases rapidly as chlorophyll is formed in the expanding leaf blade; a compensation point is reached after 30–40 hours and thereafter carbon d...
Article
A study has been made of the assimilation of ammonium salts by young barley seedlings grown under controlled conditions in water culture. The synthesis of amino acids, amides and proteins in the roots was traced by means of isotopic labelling with 15N. Chromatographic analysis on ion-exchange resins was used to separate the free and combined amino...
Article
1. The mineral nutrient status of three types of dune soil (freshly blown sand, soil of dry dune pasture and of lichen-type pasture) was investigated by means of tomato plants used as indicators. The effects on the growth and composition of turf transplants of the addition of mineral nutrients were also studied. 2. All the soils contained sufficien...
Article
The dune system and vegetation of Braunton Burrows are described, with particular regard to the distribution of the plant communities in relation to ecological conditions. The vegetation is classified largely on a topographical basis. The composition of the chief communities is expressed quantitatively; the lists of plant species together constitut...
Article
The respiration of pea seeds during the early stages of germination was studied by manometric methods. From analyses of the germinating seeds estimates were obtained of the oxidized and reduced forms of glutathione and ascorbic acid. Thus it was possible to explore the relationship between these oxidation-reduction systems and the resumption of res...
Article
AN investigation of the soluble nucleotides in food yeast (Torulopsis utilis) has shown that a complex metabolic pool of these compounds is maintained in growing cells. Marked changes in the size and composition of this pool under different physiological conditions indicate that the metabolism of nucleotides is closely related to the biosynthesis o...
Article
In an investigation on the conversion of amino acids in percolated soils, it was found that during the breakdown of glutamic acid to ammonia micro-organisms developed in the soil capable of denitrifying nitrite and nitrate to gaseous nitrogen. The enrichment of a soil with these micro-organisms was studied.
Article
Critical examination of the amino-acid composition of proteins in fast-growing and slow-growing tissues reveals only very 8maU differences, indicating that some factor other than the amino-acid complement is responsible for, or reflects, the great increase in the mass of protein in the fast-growing tissues. Increases in fresh weight and total prote...
Chapter
Many of the foundations for the study of the proteins of plant tissues are to be found in the pioneer researches of H. Ritthausen (1862–1912) and of T.B. Osborne (1859–1929). The chief objective of this early work was the separation and purification of proteins from other plant constituents; Osborne (1924) in particular described methods for the pr...
Chapter
The cellular mechanisms underlying the synthesis and breakdown of highly specific protein structures are of basic interest in many branches of biological study. But, despite the varied attacks which have been made on the problems of protein metabolism, many of the biochemical mechanisms, and especially those concerned in protein synthesis, remain u...

Citations

... Many species of Zygophyllaceae such as Zygophyllum coccineum L. are widely distributed in desert areas in Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates and Yemen (Raaelli et al. 2003, Ghazanfar & Osborne 2015, Alzahrani & Albokhari 2017. Several nitrogen-fixing bacteria have beed recorded from Z. coccineum so far (Sabet 1946, Mothes 2013. We are studying fungal diversity and beneficial microbes in desert habitats in Oman (Maharachchikumbura et al. 2016, Al Dughaishi et al. 2018, Al-Nadabi et al. 2018, Halo et al. 2018. ...
... One well known challenge, however, lies in its insufficient air-stability. During the reaction with amino acids, ninhydrin needs to be reduced, or hydrindantin, a reduced form of ninhydrin, is added directly to the reaction mixture [2]. Since the reducing agents are susceptible to oxidation, the system must be constantly kept under inert gas. ...
... Comparative studies of the amino acid composition of legumin and vicilin of peas have been reported by a number of workers (Yemm, 1958;Goa and Strid, 1959;Grant and Lawrence, 1964). These indicated that both proteins have similar amino acid profiles and contain a high content of aspartic acid, glutamic acid and arginine. ...
... After extraction, the colorless aqueous methanolicphase (containing the amino acids) was separated from the chloroform-phase (containing pigments and lipids; [31] ). The solid residue was boiled gently for 10 min in 40 ml water to extract the residual amino acids [32] . After cooling to room temperature and centrifugation at 10,000 × g, the aqueous extract was combined with the methanolic extract and made up to 100 ml. ...
... Coastal sand dunes are exposed to drought and salinity stress (Hesp 1991) and are notoriously deficient in major plant nutrients, especially N and P (Willis and Yemm 1961;Willis 1963;Hesp 1991). They are widespread in the Eastern Mediterranean region where they developed largely in calcareous sands (Doody 2013). ...
... They are expected to be particularly sensitive to environmental changes due to complex interactions between hydrology, nutrient inputs and plant communities (Curreli et al., 2013;Rhymes et al., 2016). Depth to the water table, seasonal fluctuations and duration of drought or flood can alter species interactions and therefore community assembly Willis et al., 1959). The hydrological regime also influences nutrient levels within the dunes, with high water levels maintaining low nitrogen and phosphorus (Lammerts & Grootjans, 1997). ...
... The concentrations of total soluble sugars and starch were analyzed by the anthrone method as described by Yemm and Willis [25]. Finely ground fresh tissue (approximately 150 mg) was homogenized in 3 mL of 80% ethanol and incubated in an ultrasonic bath for 30 min at 80°C. ...
... Described as the transient "wrong way" stomatal response (Buckley, 2005), it is thought to be an effect of sudden loss of turgor pressure in subsidiary epidermal cells, releasing pressure on guard cells and increasing aperture (Darwin and Pertz, 1911;Iwanoff, 1928;Willis et al., 1963;Raschke, 1970). Raschke (1970) described a stomatal response on a time scale similar to that observed in the present study in which a decrease in xylem of Zea mays was transmitted to stomata in 0.1 s, causing g s to increase. ...
... Maintaining higher level of chlorophyll content in leaf is one of the strategies for increasing photosynthesis and crop production [14]. The structure and function of chloroplasts determine photosynthetic activity [25]. Von Kroff et al. [26] reported a positive correlation between relative chlorophyll fluorescence in leaf and grain yield. ...
... Secondly, it has been shown that nitrate and ammonia have essentially the same effect on the production of free amino acids and proteins (17,26). Finally, ammonia has been shown to be directly incorporated into organic nitrogenous substances via glutamate and glutamine (4,26). ...