5 resultados para slifetime-based garbage collection
em National Center for Biotechnology Information - NCBI
Resumo:
SBASE 8.0 is the eighth release of the SBASE library of protein domain sequences that contains 294 898 annotated structural, functional, ligand-binding and topogenic segments of proteins, cross-referenced to most major sequence databases and sequence pattern collections. The entries are clustered into over 2005 statistically validated domain groups (SBASE-A) and 595 non-validated groups (SBASE-B), provided with several WWW-based search and browsing facilities for online use. A domain-search facility was developed, based on non-parametric pattern recognition methods, including artificial neural networks. SBASE 8.0 is freely available by anonymous ‘ftp’ file transfer from ftp.icgeb.trieste.it. Automated searching of SBASE can be carried out with the WWW servers http://www.icgeb.trieste.it/sbase/ and http://sbase.abc.hu/sbase/.
Resumo:
Selecting resources for physician assistants is challenging and can be overwhelming. Although several core lists exist for nursing, allied health, and medical libraries, judging the scope and level of these resources in relation to the information needs of the physician assistant is difficult. Medical texts can be highly specialized and very expensive, in essence, “overkill” for the needs of the physician assistant. This bibliography is meant to serve as a guide to appropriate medical texts for physician assistants. Titles were selected from the Brandon/Hill list, Doody's Electronic Journal, and various other reference resources. Resources were evaluated based on the subject and scope, audience, authorship, cost, and currency. The collection includes 195 titles from 33 specialty areas. Standard texts in each area are also included.
Resumo:
Several recent reports indicate that mobile elements are frequently found in and flanking many wild-type plant genes. To determine the extent of this association, we performed computer-based systematic searches to identify mobile elements in the genes of two "model" plants, Oryza sativa (domesticated rice) and Arabidopsis thaliana. Whereas 32 common sequences belonging to nine putative mobile element families were found in the noncoding regions of rice genes, none were found in Arabidopsis genes. Five of the nine families (Gaijin, Castaway, Ditto, Wanderer, and Explorer) are first described in this report, while the other four were described previously (Tourist, Stowaway, p-SINE1, and Amy/LTP). Sequence similarity, structural similarity, and documentation of past mobility strongly suggests that many of the rice common sequences are bona fide mobile elements. Members of four of the new rice mobile element families are similar in some respects to members of the previously identified inverted-repeat element families, Tourist and Stowaway. Together these elements are the most prevalent type of transposons found in the rice genes surveyed and form a unique collection of inverted-repeat transposons we refer to as miniature inverted-repeat transposable elements or MITEs. The sequence and structure of MITEs are clearly distinct from short or long interspersed nuclear elements (SINEs or LINEs), the most common transposable elements associated with mammalian nuclear genes. Mobile elements, therefore, are associated with both animal and plant genes, but the identity of these elements is strikingly different.
Resumo:
Muller proposed that an asexual organism will inevitably accumulate deleterious mutations, resulting in an increase of the mutational load and an inexorable, ratchet-like, loss of the least mutated class [Muller, H.J. (1964) Mutat. Res. 1, 2-9]. The operation of Muller's ratchet on real populations has been experimentally demonstrated only in RNA viruses. However, these cases are exceptional in that the mutation rates of the RNA viruses are extremely high. We have examined whether Muller's ratchet operates in Salmonella typhimurium, a DNA-based organism with a more typical genomic mutation rate. Cells were grown asexually under conditions expected to result in high genetic drift, and the increase in mutational load was determined. S. typhimurium accumulated mutations under these conditions such that after 1700 generations, 1% of the 444 lineages tested had suffered an obvious loss of fitness, as determined by decreased growth rate. These results suggest that in the absence of sex and with high genetic drift, genetic mechanisms, such as back or compensatory mutations, cannot compensate for the accumulation of deleterious mutations. In addition, we measured the appearance of auxotrophs, which allowed us to calculate an average spontaneous mutation rate of approximately 0.3-1.5 x 10(-9) mutations per base pair per generation. This rate is measured for the largest genetic target studied so far, a collection of about 200 genes.
Resumo:
We have synthesized two sets of noncleavable peptide-inhibitor libraries to map the S and S' subsites of human heart chymase. Human heart chymase is a chymotrypsin-like enzyme that converts angiotensin I to angiotensin II. The first library consists of peptides with 3-fluorobenzylpyruvamides in the P1 position. (Amino acid residues of substrates numbered P1, P2, etc., are toward the N-terminal direction, and P'1, P'2, etc., are toward the C-terminal direction from the scissile bond.) The P'1 and P'2 positions were varied to contain each one of the 20 naturally occurring amino acids and P'3 was kept constant as an arginine. The second library consists of peptides with phenylalanine keto-amides at P1, glycine in P'1, and benzyloxycarbonyl (Z)-isoleucine in P4. The P2 and P3 positions were varied to contain each of the naturally occurring amino acids, except for cysteine and methionine. The peptides of both libraries are attached to a solid support (pins). The peptides are evaluated by immersing the pins in a solution of the target enzyme and evaluating the amount of enzyme absorbed. The pins with the best inhibitors will absorb most enzyme. The libraries select the best and worst inhibitors within each group of peptides and provide an approximate ranking of the remaining peptides according to Ki. Through this library, we determined that Z-Ile-Glu-Pro-Phe-CO2Me and (F)-Phe-CO-Glu-Asp-ArgOMe should be the best inhibitors of chymase in this collection of peptide inhibitors. We synthesized the peptides and found Ki values were 1 nM and 1 microM, respectively. The corresponding Ki values for chymotrypsin were 10 nM and 100 microM. The use of libraries of inhibitors has advantages over the classical method of synthesis of potential inhibitors in solution: the libraries are reusable, the same libraries can be used with a variety of different serine proteases, and the method allows the screening of hundreds of compounds in short periods of time.