The objective of the study was to assess the semen characteristics of Jersey, Mithun and Siri breeds of bulls and to compare the suitability of Tris Eggyolk Citrate and commercial soya lecithin based BIOXcell extenders for cryopreservation of semen from the these breeds of bulls. The mean semen volume was 4.55± 1.57, 4.86±1.33 and 4.83±1.72 ml in Jersey, Mithun and Siri bulls, respectively. Mea...

Many theories have been proposed to account for the accumulation of citrate in selected strains of Aspergillus niger (Berry et al., 1977). Citrate accumulation was attributed by Ramakrishnan et al. (1955) to loss of aconitase and isocitrate dehydrogenase activity, but the presence of these enzymes was clearly demonstrated by La Nauze (1966). The presence of tricarboxylic acid-cycle enzymes thro...

In an attempt to identify components of a ferric citrate uptake system in Pseudomonas aeruginosa, a mutant library of a siderophore-deficient strain (IA614) was constructed and screened for defects in citrate-promoted growth in an Fe-restricted medium. A mutant disrupted in gene PA3901, encoding a homologue of the outer-membrane ferric citrate receptor, FecA, of Escherichia coli (FecA(E.c.)), w...

1. Photosynthetic electron transport from water to lipophilic Photosystem II acceptors was stimulated 3--5-fold by high concentrations (greater than or equal to 1 M) of salts containing anions such as citrate, succinate and phosphate that are high in the Hofmeister series. 2. In trypsin-treated chloroplasts, K3Fe(CN)6 reduction insensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea was strongly...

The effect of the relative concentrations of citrate and glucose on the regulation of key enzymes of the direct oxidative, phosphorylative, Entner-Doudoroff and pentose-cycle pathways of glucose metabolism in Pseudomonas aeruginosa has been investigated in continuous culture under conditions of NH(4) (+)-limitation. For comparison isocitrate dehydrogenase and aconitase were also assayed. Measur...

In mycobacterial growth medium 40 to 400 microM citrate was required to solubilize 2 microM 55Fe. This solubilized 55Fe was taken up into both iron-deficient and iron sufficient washed cell suspensions of Mycobacterium smegmatis and Mycobacterium bovis BCG. Although the 55Fe was taken up into the cell, the citrate was not. The uptake system with M. smegmatis was not inhibited by electron transp...

A method for preparing highly purified glutaminase (EC 3.5.1.2, L-glutamine amidohydrolase) from pig renal cortex is described. The main steps consist of sodium sulfate fractionation followed by alternative solubilization by dialysis against Tris-HCI buffer and precipitation with phosphateborate. The linal enzyme preparation contains no impurities which could be detected by sucrose gradient cen...

The absorption of dietary calcium (Ca) may in part be determined by the formation in the intestinal lumen of soluble Ca complexes and insoluble Ca salts. This study was undertaken to test the assumption that ionic Ca concentration (Ca2+) is the only species of Ca that is available for absorption. Bidirectional steady-state Ca fluxes were measured in vitro under short-circuit conditions across s...

After 1 hour, exogenous deoxyribonucleic acid was degraded within a culture medium at 25 C (pH 6) containing protoplasts of Daucus carota L. var. sativa. Low temperature incubation (1 C) or the addition of 45 millimolar sodium citrate to the medium eliminated DNase activity for at least 4.5 hours. This DNase activity was not reduced at pH 7 or 9, nor by addition of 200 millimolar adenosine 5'-t...