Strigolactones, phytohormones with diverse signaling activities, have a common structure consisting of two lactones connected by an enol-ether bridge. Strigolactones derive from carotenoids via a pathway involving the carotenoid cleavage dioxygenases 7 and 8 (CCD7 and CCD8) and the iron-binding protein D27. We show that D27 is a β-carotene isomerase that converts all-trans-β-carotene into 9-cis-β-carotene, which is cleaved by CCD7 into a 9-cis-configured aldehyde. CCD8 incorporates three oxygens into 9-cis-β-apo-10'-carotenal and performs molecular rearrangement, linking carotenoids with strigolactones and producing carlactone, a compound with strigolactone-like biological activities. Knowledge of the structure of carlactone will be crucial for understanding the biology of strigolactones and may have applications in combating parasitic weeds.

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We compared in vitro 1H magnetic resonance spectroscopy (MRS) measurements of rat brain extracts (rats: 2-56 days old) with chromatographic measurements and in a further step also with results of in vitro MRS. The following substances can be reliably measured in brain extracts by in vitro MRS: N-acetylaspartate (NAA), total creatine (Cr), phosphorylethanoloamine (PE), taurine (Tau), glutamate (Glu), glutamine (Gln), gamma-aminobutyrate (GABA) and alanine (Ala). Two different methods of MRS data evaluation compared with chromatographic data on Cr and NAA are shown. During development of the rat from day 2-56 brain concentrations of PE, Tau and Ala decrease, those of NAA, Cr, Glu and Gln increase, while GABA does not change. The developmental patterns of these substances are the same, whether measured by in vitro MRS or by chromatographic methods. Quantification of NAA, Cr, Tau, GABA and PE leads to the same results with both methods, while Glu, Gln and Ala concentrations determined by in vitro MRS are apparently lower than those measured chemically. The NAA/Cr ratios of 7 to 35-day-old rats were determined by in vivo 1H MRS. These results correlate with chromatographic and in vitro data. Using appropriate methods in the in vivo and in vitro MR-technique, the obtained data compare well with the chromatographic results.

One of the most important and most difficult tasks of a forensic investigation is the estimation of the time span passed between death and recovery of the body, in particular if a body remained undiscovered for more than 2 days. Under these circumstances, the common indicators for the estimation of the postmortem interval (PMI), i.e., rigor mortis, livor mortis, and the body's core temperature, will have reached steady state in most cases.Since the early 1970s various chemical methods have been developed in order to ameliorate and extend PMI estimation, e.g., using blood and serum (1), cerebrospinal fluid (2), vitreous humor (3,4), skeletal muscle (5), and liver (6). Brain tissue remained largely excluded from these investigations, despite the fact that interindividual differences in tissue composition are very small and that the skull represents a natural barrier against external factors. Daldrup (7, and Refs. therein) proposed a formula for the time of death for PMIs of up to 20 days using the changes in the concentration of amino acids that occur during brain decomposition. The limited success of these methods might also be a consequence of the time-consuming and labor-intensive chemical analysis required.Proton magnetic resonance spectroscopy ( 1 H-MRS) has been used to study brain autolysis (8 -11); however, not in situations that are relevant for forensic sciences. Most examinations dealt with the influence of the conditions and the time span between autopsy or surgical removal of tissue samples and the moment of chemical analysis. These studies covered time ranges of up to 195 hr for "sterile" test tube conditions (11), up to 24 hr postmortem (8,10) for autopsied, nonsterile samples at room temperature, and up to 120 hr at a storage temperature of 4°C (8). Short-term changes were investigated in dog brain in situ up to 24 hr in the clinically relevant case of global ischemia (9).The later phase of brain decomposition is governed by bacterial growth (12), resembling the situation in an abscess in vivo. 1 H-MRS has been found valuable to distinguish between abscess and other cystic lesions, in particular tumors (13)(14)(15).The eventual goal of the present investigation is an estimation of PMI up to 3 weeks, based on changes in the concentration of brain metabolites determined by 1 H-MRS in situ and quantitative analysis of the spectra by the program LC Model (16). In a first step, a sheep model was used to study brain decomposition longitudinally. The metabolite patterns obtained in this model were compared with selected human cases to investigate if the chosen model is qualitatively representative for human bodies. Metabolites that are not present in vivo are identified and included in the basis set for LC Model to check the assignments in situ. In particular, free trimethylammonium (fTMA, not to be confused with TMA compounds that occur in brain in vivo), propionic acid (Prop), butyrate (But), and iso-butyrate (iBut) were found postmortem in both sheep and human brain tissue. Following a characterization...

Ypr118w is a non-essential, low copy number gene product from Saccharomyces cerevisiae. It belongs to the PFAM family PF01008, which contains the ␣-, ␤-, and ␦-subunits of eukaryotic translation initiation factor eIF2B, as well as proteins of unknown function from all three kingdoms. Recently, one of those latter proteins from Bacillus subtilis has been characterized as a 5-methylthioribose-1-phosphate isomerase, an enzyme of the methionine salvage pathway. We report here the crystal structure of Ypr118w, which reveals a dimeric protein with two domains and a putative active site cleft. The C-terminal domain resembles ribose-5-phosphate isomerase from Escherichia coli with a similar location of the active site. In vivo, Ypr118w protein is required for yeast cells to grow on methylthioadenosine in the absence of methionine, showing that Ypr118w is involved in the methionine salvage pathway. The crystal structure of Ypr118w reveals for the first time the fold of a PF01008 member and allows a deeper discussion of an enzyme of the methionine salvage pathway, which has in the past attracted interest due to tumor suppression and as a target of aniprotozoal drugs.The Saccharomyces cerevisiae gene YPR118W is a non-essential gene on chromosome 16 encoding an acidic protein (pI 4.89) of 411 amino acids, Ypr118w, the function of which is unknown (1) and which is of rather low abundance (922 molecules/cell (2). Ypr118w belongs to the PFAM family PF01008 and the TIGR 00512 and 00524 families, the latter also being called eIF2B-related (eIF2B_rel) (3-5). Members of PF01008 contain the ␣-, ␤-, and ␦-, but not the catalytically active ⑀-, subunits of eukaryotic translation initiation factor 2B (eIF2B) 1 from yeast and mammals (4, 5) (Fig. 1). eIF2B is an important regulator of translation initiation. In eukaryotic translation initiation, a ternary complex consisting of Met-tRNA i , GTP, and the heterotrimeric initiation factor eIF2 (6, 7) associates with the 40 S ribosomal subunit together with other initiation factors to form the 43 S preinitiation complex. This complex binds close to the 5Ј-end of mRNA and scans it in the 5Ј-to 3Ј-direction to localize the AUG initiation codon. AUG recognition is mediated by codon-anticodon interaction and involves GTP hydrolysis stimulated by eIF5. This is a prerequisite for the 80 S initiation complex formation, i.e. the joining of the large ribosomal subunit and the release of initiation factors bound to the 40 S ribosomal subunit. After its release, the eIF2-GDP complex is bound by eIF2B, which catalyzes the exchange of GDP for GTP.