Quantitative trait loci that modify the sootiness of yellow pigmentation in KK-A y /a mice

Compared with C57BL/6J-A ^y /a, KK-A ^y /a mice have yellow fur that is markedly darker. Furthermore, there is a considerable variation in the tone of color with a continuous range in F₂ progeny produced from C57BL/6J females and KK-A ^y /a males. The aims of this study are to reveal the phenotypic differences between the two A ^y congenic strains and to elucidate the genetic factors responsible for the sooty yellow pigmentation in the KK background. On the basis of a chemical analysis, the sootiness in KK-A ^y /a was the result of increased eumelanin (PTCA) and decreased pheomelanin (AHP). A statistically significant QTL was identified on Chromosome (Chr) 15, responsible for the AHP content. No significant loci responsible for PTCA were identified. On the other hand, on the basis of an optical analysis for color difference and overall sootiness, significant evidence of linkage was identified on the proximal part of Chr 15, in the region similar to AHP QTL. The overall sootiness is thus controlled solely by the locus on Chr 15 in F₂ progeny; however, the KK allele at this locus significantly increased the AHP content. Received: 8 September 1999 / Accepted: 18 April 2000     

The effects of several nucleotides on the molecular state and catalytic activity of Thiobacillus novellus cytochrome c oxidase. ATP affects the oxidase uniquely.

The catalytic activity and molecular aspects of Thiobacillus novellus cytpchrome c oxidase were affected by ATP. The steady-state kinetics in the oxidation of ferrocytochrome c by the oxidase varied with the presence or absence of ATP; the [S]-v curve of the reaction was sigmoid in the absence of ATP whereas it was a Michaelis-Menten-type hyperbola in the presence of 700 microM ATP. The oxidase was a dimer of the minimal structural subunit consisting of one molecule each of two subunits in the presence of Tween 20 and in the absence of ATP. The dimer dissociated into monomers in the presence of 700 microM ATP. The trough at 452 nm seen in the second derivative absorption spectrum of the CO compound of the oxidase in the absence of ATP, a characteristic of the cytochrome a component of cytochrome aa3, dissappeared in the presence of 700 microM ATP. However, ADP, AMP, GTP, CTP and UTP had little affect on both the [S]-v curve and the molecular mass of the oxidase when used in place of ATP.     

Inhibition of thermolysin by 3-trimethylsilylalanine derivatives

The inhibition of thermolysin by an optically active silicon-containing amino acid, 3-trimethylsilylalanine (TMS-Ala), and its derivatives was examined by considering the similarity of structure between TMS-Ala and leucine. Although free l- and d-TMS-Ala did not show the inhibition, several derivatives of l-TMS-Ala, especially Z-l-TMS-Ala and l-Leu-(l-TMS-Ala), exhibited a higher inhibitory activity toward thermolysin than did Z-l-Leu and l-Leu-l-Leu respectively. Effects of TMS-Ala on the activity of its derivatives and the mode of interaction between the derivatives of TMS-Ala and thermolysin are also discussed. Received: 24 February 1999 / Received last revision: 4 June 1999 / Accepted: 27 June 1999     

Purification and properties of Halobacterium halobium "cytochrome aa3" which lacks CuA and CuB

An a-type cytochrome was purified from Halobacterium halobium. The cytochrome showed an absorption spectrum similar to that of cytochrome aa3; it showed absorption peaks at 420 and 598 nm in the resting state, peaks at 441 and 602 nm in the reduced form, and its CO compound showed peaks at 430 and 600 nm. The cytochrome molecule was composed of only one kind of polypeptide with the molecular weight of 40,000. The cytochrome contained two heme a molecules in the molecule but no copper. The cytochrome did not show cytochrome c oxidase activity. Midpoint redox potential at pH 8.0 of the cytochrome was determined to be +0.31 V. The amino acid composition of the cytochrome resembled that of subunit I of mitochondrial cytochrome aa3. While two molecules of heme a were reduced with sodium dithionite, only one of two heme a molecules was reduced with ascorbate plus TMPD. The heme a reduced with ascorbate plus TMPD did not react with molecular oxygen or carbon monoxide, while one of two heme a molecules reduced with sodium dithionite was oxidized by molecular oxygen and combined with carbon monoxide.     

Stereochemistry of the guanyl nucleotide binding site of transducin probed by phosphorothioate analogues of GTP and GDP

The stereochemistry of the guanyl nucleotide binding site of transducin from bovine retinal rod outer segments was probed with phosphorothioate analogues of GTP and GDP. Transducin has markedly different affinities for the five thio analogues of GTP, as measured by their effectiveness in inhibiting GTPase activity, competing with GTP for entry into transducin, and displacing GDP bound to transducin. The order of binding affinities is GTP gamma S = (Sp)-GTP alpha S greater than (Rp)-GTP alpha S greater than (Sp)-GTP beta S much greater than (Rp)-GTP beta S. The affinity of transducin for GTP gamma S is greater than 10(4) higher than that for (Rp)-GTP beta S. These five analogues have the same relative potencies in eliciting the release of transducin from the membrane and in activating the phosphodiesterase. Transducin hydrolyzes (Sp)-GTP alpha S with a l/e time of 55 s, compared with 28 s for GTP. In contrast, (Rp)-GTP alpha S, like GTP gamma S, is not hydrolyzed on the time scale of several hours. The order of effectiveness of thio analogues of GDP in displacing bound GDP is (Sp)-GDP alpha S greater than GDP greater than (Rp)-GDP alpha S greater than GDP beta S. The affinity of transducin for (Sp)-GDP alpha S is about 10-fold higher than that for GDP beta S. Mg2+ is required for the binding of GTP and GDP to transducin. Cd2+ does not lead to a reversal of stereospecificity at either the alpha- or beta-phosphorus atom of GTP. These results lead to the following conclusions: The pro-R oxygen atom at the alpha-phosphorus of GTP does not bind Mg2+ but instead interacts with the protein. The pro-S oxygen at the alpha-phosphorus does not appear to be involved in a critical interaction with transducin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chain elongation of fusaric acid and related compounds in rat liver

Chain elongation of fusaric acid and related compounds in the presence of rat liver preparations was investigated by gas chromatography-mass spectrometry. The mitochondrial fraction catalyzed the elongation of the CoA esters of fusaric acid and 5-butyl-2-pyrimidinecarboxylic acid utilizing acetyl-CoA as a C2 donor. The microsomal fraction failed to afford elongation products. However, when the CoA ester of 3-(5-butyl-2-pyrimidinyl)-3-hydroxypropionic acid was incubated in the presence of the mitochondrial or the microsomal fraction, the corresponding alpha beta-unsaturated and saturated metabolites were identified in both cases, suggesting that the microsomal fraction could not catalyze the condensation or the keto-reduction of these heteroaromatic carboxylic acids.     

Developmental variation and amino acid sequences of cytochromes c of the fruit fly Drosophila melanogaster and the flesh fly Boettcherisca peregrina

The amino acid sequences of cytochromes c purified from the fruit fly Drosophila melanogaster and the flesh fly Boettcherisca peregrina were determined. In contrast with the case of the housefly, isocytochromes c were not detected in these flies at any developmental stage. The sequence of fruit fly cytochrome c differed from that reported previously but was identical with that predicted from the nucleotide sequence of the fruit fly cytochrome c gene (DC4) (Limbach, K.J. & Wu, R. (1985) Nucl. Acids Res. 13, 631-644). Isocytochrome c of the fruit fly, reported to be encoded by the DC3 gene, was not detected as a functional cytochrome c molecule.     

Biodegradation of polyethylene glycol by symbiotic mixed culture (obligate mutualism)

Neither Flavobacterium sp. nor Pseudomonas sp. grew on a polyethylene glycol (PEG) 6000 medium containing the culture filtrate of their mixed culture on PEG 6000. The two bacteria did not grow with a dialysis culture on a PEG 6000 medium. Flavobacterium sp. grew well on a dialysis culture containing a tetraethylene glycol medium supplemented with a small amount of PEG 6000 as an inducer, while poor growth of Pseudomonas sp. was observed. Three enzymes involved in the metabolism of PEG, PEG dehydrogenase, PEG-aldehyde dehydrogenase and PEG-carboxylate dehydrogenase (ether-cleaving) were present in the cells of Flavobacterium sp. The first two enzymes were not found in the cells of Pseudomonas sp. PEG 6000 was degraded neither by intact cells of Flavobacterium sp. nor by those of Pseudomonas sp., but it was degraded by their mixture. Glyoxylate, a metabolite liberated by the ether-cleaving enzyme, inhibited the growth of the mixed culture. The ether-cleaving enzyme was remarkably inhibited by glyoxylate. Glyoxylate was metabolized faster by Pseudomonas sp. than by Flavobacterium sp., and seemed to be a key material for the symbiosis.     

Net protein utilization of stock diets for rats and mice

Male Sprague-Dawley rats of six weeks of age were fed on ten percent crude protein diets for a ten day experimental period. The net protein utilization (NPU) by carcass analysis of six kinds of revised stock diets for rats and mice was compared with that of purified whole-egg protein and milk casein. NPU values for all revised stock diets and milk casein were lower than those for purified whole-egg protein. Compared to milk casein, two kinds of revised stock diets showed lower NPU, but the remaining four diets had similar NPU.     

Compression neuropathy from muscle fibrosis induced by repeated meperidine injections

The combination of myopathy and neuropathy with fibrosis and contractures has apparently not yet been reported from the use of meperidine. We describe a patient addicted to meperidine in whom bilateral hand numbness and weakness developed and electrodiagnostic studies revealed moderate slowing of motor nerve conduction velocities. Neurolysis of the median and ulnar nerves resulted in markedly improved symptoms.