Adipocyte conversion of cultured 3T3-L1 preadipocytes by bezafibrate

Transient exposure of cultured 3T3-L1 preadipocytes to hypolipidemic fibrate drugs results in extensive adipocyte conversion. Adipocyte conversion in culture was characterized by an increase in neutral lipids content and in adipocyte marker enzymes like hormone-sensitive lipase and glycerol-3-phosphate dehydrogenase. Adipocyte conversion in culture was also accompanied by induction of cyanide-insensitive peroxisomal palmitoyl-CoA oxidation. The conversion pattern exerted by fibrate drugs in 3T3-L1 cells was similar to that reported previously for primary cultured epididymal preadipocytes (R. Brandes, R. Arad and J. Bar-Tana, Biochim. Biophys. Acta, 877, 314-321 (1986)), and seems to refute clonal selection in the conversion sequel initiated by fibrate drugs in primary cultured preadipocytes.     

In vitro synthesis of bean (Phaseolus vulgaris) chloroplastic and cytoplasmic leucyl-tRNA synthetases. Characterization and processing of a precursor polypeptide for the chloroplast enzyme

Bean (Phaseolus vulgaris) chloroplastic and cytoplasmic leucyl-tRNA synthetases differ in their structural and catalytic properties and do not share common antigenic determinants. Polyadenylated mRNAs, prepared from young bean leaves, have been translated in vitro in a rabbit reticulocyte lysate cell-free system. The newly synthesized polypeptides have been submitted to immunoadsorption on protein A-Sepharose in the presence of the antibodies raised against the chloroplastic or the cytoplasmic leucyl-tRNA synthetase. The specificity of the immunoadsorption has been checked by competition experiments involving the pure enzymes. Bean chloroplastic leucyl-tRNA synthetase is synthesized in vitro from a polyadenylated mRNA as a precursor polypeptide of 130 kDa, which is somewhat larger than the mature enzyme of 120 kDa. Bean cytoplasmic leucyl-tRNA synthetase is synthesized in vitro as a polypeptide which has the size of the mature monomer (130 kDa). Processing of the precursor polypeptide of the chloroplastic leucyl-tRNA synthetase, yielding the mature enzyme, has been obtained by performing the in vitro translation in the presence of canine pancreatic microsomal membranes. These results suggest that in vivo bean chloroplastic leucyl-tRNA synthetase could be synthesized in the cytoplasm as a precursor which would be transported into the chloroplasts.     

To produce many small or few large eggs: a size-independent reproductive tactic of fish

Summary We demonstrate here the existence of a range of size-independent reproductive tactics in teleostean fish involving the allocation of a size-dependent reproductive effort between fecundity and egg size. Despite considerable evidence that larger eggs and the larvae hatching from them are more likely to survive than smaller ones, we found no evidence of evolutionary trends towards greater egg sizes. Fish with pelagic eggs tend to spawn many, and therefore small, eggs, whereas demersal spawners tend to produce large, and therefore few, eggs. Maximizing egg number should increase the number of eggs hatching in suitable locations in the patchy pelagic environment and, hence, increase the reproductive success of pelagic spawners. On the other hand, the reproductive success of demersal spawners, which reduce the variance in growing conditions experienced by the off spring, should be more dependent on the survival of the individual larvae, which increases as egg size increases.     

Bacterial Metabolism of 2,6-Xylenol

Strain DM1, a Mycobacterium sp. that utilizes 2,6-xylenol, 2,3,6-trimethylphenol, and o-cresol as sources of carbon and energy, was isolated. Intact cells of Mycobacterium strain DM1 grown with 2,6-xylenol cooxidized 2,4,6-trimethylphenol to 2,4,6-trimethylresorcinol. 4-Chloro-3,5-dimethylphenol prevents 2,6-xylenol from being totally degraded; it was quantitatively converted to 2,6-dimethylhydroquinone by resting cells. 2,6-Dimethylhydroquinone, citraconate, and an unidentified metabolite were detected as products of 2,6-xylenol oxidation in cells that were partially inactivated by EDTA. Under oxygen limitation, 2,6-dimethylhy-droquinone, citraconate, and an unidentified metabolite were released during 2,6-xylenol turnover by resting cells. Cell extracts of 2,6-xylenol-grown cells contained a 2,6-dimethylhydroquinone-converting enzyme. When supplemented with NADH, cell extracts catalyzed the reduction of 2,6-dimethyl-3-hydroxyquinone to 2,6-dimethyl-3-hydroxyhydroquinone. Since a citraconase was also demonstrated in cell extracts, a new metabolic pathway with 2,6-dimethyl-3-hydroxyhydroquinone as the ring fission substrate is proposed.     

Comparison between intra- and extracellular surfactant in respiratory distress induced by oleic acid

The present study compares the phospholipid distribution and protein content in bronchoalveolar lavage, purified extracellular surfactant and lamellar bodies isolated from rabbits killed at intervals of 2.5, 12 and 24 h after oleic acid administration. The data suggest that the alteration of pulmonary surfactant could be partially due to the type II cell response to the injury.     

The cyanelle genome of Cyanophora paradoxa, unlike the chloroplast genome, codes for the ribosomal L3 protein.

We describe a 1132 bp sequence of the cyanelle genome of Cyanophora paradoxa containing the rpl3 gene. This gene, which is not chloroplast encoded in plants, is the first of a long cyanelle ribosomal operon whose organization resembles that of the S10 operon of E. coli. We have shown that the rpl3 gene is transcribed in cyanelles as a 7500 nucleotide precursor and that the 5'-end of the mRNA starts approximately 90 nucleotides upstream from the initiation codon. However, no typical procaryotic promoter could be found for this gene. We have detected, using anti E. coli L3 antibodies, the cyanelle L3 protein in cyanelle extracts and in E. coli cells transformed with the cyanelle rpl3 gene.     

Definition of the limits of the Wilms tumor locus on human chromosome 11p13

In a previous report, we described a contiguous restriction map of chromosome band 11p13 that localized the Wilms tumor locus to a small group of NotI fragments. In an effort to identify and isolate the 11p13-associated sporadic Wilms tumor locus, we developed a panel of NotI fragment-specific DNA probes. These probes were selected from genomic libraries constructed using the Chinese hamster ovary-human somatic cell hybrid carrying only human 11p. The libraries were prepared from NotI-digested DNA after size selection by pulsed-field gel electrophoresis. The selected NotI fragments had been previously targeted on the basis of deletion mapping as having a high probability of containing the Wilms tumor locus. We used these newly identified 11p13-specific probes to improve the resolution of the restriction map spanning the Wilms tumor locus. The locus has been defined by a homozygous deletion in a sporadic Wilms tumor. Using these probes, the region of homozygous deletion in this tumor and presumably all or part of the Wilms tumor gene have been confined to two small SfiI fragments spanning less than 350 kb.