Homology and functions of inner staminodes in Anaxagorea javanica (Annonaceae)

Inner staminodes are widespread in Magnoliales and present in Anaxagorea and Xylopia, but were lost in the other genera of Annonaceae and have no counterparts in derived angiosperms. The coexistence of normal stamens, modified stamens and inner staminodes in Anaxagorea javanica is essential to understand the homology and pollination function of the inner staminodes. Anaxagorea javanica was subjected to an anatomical study by light and scanning electron microscopy, and the chemistry of secretions was evaluated by an amino acid analyser. Inner staminodes have a secretory apex, but do not have thecae. They bend towards either tepals or carpels at different floral stages, and function as a physical barrier preventing autogamy and promoting outcrossing. At the pistillate phase, the exudates from the inner staminodes have high concentration of amino acid, and provide attraction to pollinating insects; while abundant proline was only detected in stigmas exudates, and supply for pollen germination. Modified stamens have a secretory apex and one or two thecae, which are as long as or shorter than that of the normal stamens. As transitional structures, modified stamens imply a possible degeneration progress from normal stamens to inner staminodes: generating a secretory apex first, shortening of the thecae length next and then followed by the loss of thecae. The presence of modified stamens together with the floral vasculature and ontogeny imply that the inner staminodes are homologous with stamens.

Free amino acids in the environment of the proembryo during the inhibition phase of its growth (Monocotyledonuos plants)

Analyses of the central vacuole sap in the ovules of <i>H. Katharinae</i> and <i>Clivia miniata</i> (during the inhibition phase of proembryo growth) for free amino acids were carried out by means of a Micro Column Amino Acid Analyser. Some similarities and differences have been established for both speciesas regards the change of total concentration and concentration changes of particular amino acids.

Amino Acid Composition of Tamarind Fruit Growing Wild in Oyo Town

Tamarind ( Tamarindus indica L.) fruit grows wild in some parts of the savannah region of Nigeria. The fruit is grossly underutilised in Nigeria, despite its invaluable contribution to the food security and economy of some Asian countries. The amino acid composition of tamarind pulp was determined using amino acid analyser. Tamarind pulp was found to contain both essential and non-essential amino acids. Tamarind pulp could supply 53.8 %, 52.8 %, and 87.6 % of total essential, total sulphur and total aromatic amino acids respectively (FAO/WHO/UNU standard).

Change of amino acid profile in Charolais cows’ colostrum and transient milk during the first week post partum

In this study the change in amino acid profile in cow&rsquo;s colostrum and transient milk during the first week after parturition was examined in a Hungarian Charolais herd. Experiments were carried out with n = 37 Charolais cows in the same herd in the spring (March&ndash;April) of two consecutive years (Experiment 1: 2002, n = 15; and Experiment 2: 2003, n = 22). Colostrum and milk samples were taken by hand milking immediately after delivery, and in 24, 48, 72, and 168 hours post partum. Amino acid contents (%) in samples were measured in milk protein with an automatic amino acid analyser. Data were processed by the software of SPSS.10 statistical program package. In the postpartal period, among essential amino acids significant increases were recorded in methionine, isoleucine, lysine, and phenylalanine, and among non-essential amino acids glutamic acid and proline increased significantly. Simultaneous decreases were recorded in valine, cysteine, aspartic acid, serine, glycine, and arginine. Inconsistent figures were determined for histidine, leucine, tyrosine, and alanine content between Experiment 1 and Experiment 2. &nbsp; &nbsp; &nbsp;

Formation of homocitrulline during heating of milk

Homocitrulline arises from the reaction between cyanate and the ε-amino group of lysine residues; in milk, cyanate derives from heat-induced urea breakdown. Since homocitrulline levels were unknown in heated milk, its formation was studied in the temperature range 100–150°C. Firstly, an analysis method based on ion-exchange chromatography using an amino acid analyser was developed. Homocitrulline, liberated from milk protein by enzymic hydrolysis, was eluted well separated from other amino acids and could be readily distinguished using this technique. Secondly, homocitrulline levels were determined for various time–temperature combinations in samples of milk, milk to which 10 mm-urea had been added, and milk that was made urea-free. No homocitrulline was formed in urea-free milk, while homocitrulline formation was stimulated by urea addition. Upon prolonged heating, we found extensive subsequent breakdown of homocitrulline. The kinetics of homocitrulline formation was quite complicated, but an approximation was possible as the initial formation reaction could be modelled using zero order reaction kinetics. The apparent activation energy for homocitrulline formation was estimated at ∼90 kJ/mol. In general, the levels of homocitrulline to be expected in heated milk appeared to be quite low: ∼0·3 mm in in-bottle sterilized milk, and <0·01 mm in UHT sterilized milk.

Amino-acid composition of pyruvate kinase M2 isoenzyme variants from rat liver and Morris hepatoma 7777.

Cytosolic fractions B (salted out between 51-70% ammonium sulphate saturation) from rat liver and Morris hepatoma 7777, containing pyruvate kinase (EC 2.7.1.40) M2 isoenzymes, were purified by affinity chromatography on Blue Sepharose CL-6B. When compared by polyacrylamide gel electrophoresis at pH 8.3, all three M2 pyruvate kinase variants from Morris hepatoma 7777 had lower mobilities (alpha2, beta2, gamma3) than the three corresponding variants (alpha1, beta1, gamma2) from normal rat liver. Using an automatic amino-acid analyser, significant differences in selected amino-acid content have been found in corresponding highly purified gamma3 and gamma2 variants from Morris hepatoma and normal rat liver, respectively. The gamma3-variant of the Morris hepatoma M2 isoenzyme had twice the amount of L-tyrosine and L-cysteine, and a content of L-serine higher by 20% than the corresponding gamma2 variant of the normal rat liver M2 isoenzyme. It contained, however, significantly less dicarboxylic amino acids which explains its lower electrophoretic mobility. It showed also a decrease (by about 10%) in several other amino-acid content, corresponding to a 10% decrease in the tumour enzyme molecular mass.