Lipoprotein lipase activator deficiency in very low density lipoproteins in rat nephrotic syndrome.

Marked urinary loss of lipoprotein lipase activator in experimental rat nephrotic syndrome may be partly responsible for its deficiency in plasma very low density lipoproteins.     

Structure and assembly of the 20S proteasome

The barrel-shaped 20S proteasome is one of the two components of a larger 26S particle, the multicatalytic 2000-kDa protease complex. The proteolytic sites are located in the inner chamber of the 20S particle and are only accessible via narrow entrances. This paper reviews the current knowledge concerning proteasome formation, proteolytic activities, structural aspects and assembly. Eukaryotic proteasomes are made up by four rings each of which contains seven different subunits occurring at fixed positions. While the outer rings contain α-type subunits, the inner ones comprise β-type subunits. The current assembly model for eukaryotic 20S proteasomes is based upon the detection of 13S and 16S intermediates, respectively, in addition to previous findings with archaebacterial and eubacterial proteasome assembly. The available data suggest a cooperative assembly of the α-type and β-type subunits into half proteasome-like complexes followed by dimerization into proteasomes. During or after dimerization of half proteasomes, the β-type subunits are processed. The prosequence of the β-type subunits is essential for the assembly process and prevents protease activity of immature proteasomes.     

Maize HapMap2 identifies extant variation from a genome in flux

Whereas breeders have exploited diversity in maize for yield improvements, there has been limited progress in using beneficial alleles in undomesticated varieties. Characterizing standing variation in this complex genome has been challenging, with only a small fraction of it described to date. Using a population genetics scoring model, we identified 55 million SNPs in 103 lines across pre-domestication and domesticated Zea mays varieties, including a representative from the sister genus Tripsacum. We find that structural variations are pervasive in the Z. mays genome and are enriched at loci associated with important traits. By investigating the drivers of genome size variation, we find that the larger Tripsacum genome can be explained by transposable element abundance rather than an allopolyploid origin. In contrast, intraspecies genome size variation seems to be controlled by chromosomal knob content. There is tremendous overlap in key gene content in maize and Tripsacum, suggesting that adaptations from Tripsacum (for example, perennialism and frost and drought tolerance) can likely be integrated into maize.     

Luffolide,a novel anti-inflammatory terpene from the spongeLuffariella sp.

Summary Luffolide (4) is a minor metabolite of the spongeLuffariella sp. from Palau. The structure of luffolide was determined by single crystal X-ray analysis. Luffolide is relatively unstable and undergoes a complex cyclization reaction to give the hexacyclic products5 and6. Luffolide (4) has some of the anti-inflammatory properties of manoalide (1): this may help to define the chemical reaction between manoalide (1) and phospholipase A₂.All crystallographic calculations were done on a PRIME 9950 computer operated by the Cornell Chemistry Computing Facility. Principal programs employed were: FOBS, a data reduction program by G.D. Van Duyne, Cornell University, 1987; MULTAN 80, and RANTAN 80, systems of computer programs for the automatic solution of crystal structures from X-ray diffraction data (locally modified to perform all Fourier calculations including Patterson syntheses) written by P. Main, S. E. Hull, L. Lessinger, G. Germain, J. P. Declercq and M. M. Woolfson, University of York, England, 1980 BDLS, an, anisotropic block diagonal least squares refinement written by K. Hirotsu, E. Arnold, and G. D. Van Duyne, Cornell University, 1987; PLUTO 78, a locally modified crystallographic illustration program by W. D. S. Motherwell, Cambridge Crystallographic Data Centre, 1978; and BOND, a program to calculate molecular parameters and prepare tables written by K. Hirotsu and G. Van Duyne, Cornell University, 1985.Acknowledgment. We thank the Government of the Republic of Palau for a scientific research permit. We thank Dr Klaus Rützler, Smithsonian Institution, Washington, D.C. for identifying the sponge and Mary Kay Harper for performing additional bioassays. This research was supported by grants from the Sea Grant College Programs of California [Projects R/MP-30 to DJF) and R/MP-31 (to RSJ)] and New York (to JC) and the National Institutes of Health (CA 24487 to JC).