Issues critical to ensuring semantic integrity in molecular biological data collections have been identified and include complexity, exceptions, missing data, changing models, holism and integration, delocalized data, interoperability and nomenclature. This combination is peculiar to biology and presents some interesting problems as a result. Little is known about semantic checking in object-oriented databases in general, but because such technology appears highly suitable for modeling biological data, it is appropriate to examine the ways in which object-oriented technology can support this functionality. It is concluded that object-oriented technology will support semantic checking even in a complex domain like biology. We propose 10 guidelines for future work including ways of treating exceptional cases and 'positioning' of constraints in a schema.

Overseer is a computer program that searches databases of nucleic acid sequences for objects of interest to the user. Such objects may consist of any number of simpler building blocks such as repeats, palindromes or stem-loops, strings of particular bases with or without mismatches, etc. Written in standard Pascal, this program runs under Unix and VMS and should also run under other operating systems. A simple interface allows the user to generate interactively a file containing a description of the target to be found. The searching program runs non-interactively, processing the information from the file and searching the sequences. The results are output to a file. Search capabilities are quite flexible and the code is designed to be modified. Since the framework of the program is simple, adding new modules to search for new target types as the need arises is possible.

The protein sequence searching program Scrutineer has been modified to search for targets from a file. We are distributing a reformatted file of PROSITES which can be read by Scrutineer. In addition, Scrutineer still accepts targets typed in interactively but can now write them out in the format required as input. Since the input format is the same as the output format, target management and re-use is simple.

Scrutineer is an interactive, user-friendly program designed to search for motifs, patterns and profiles in the Swissprot, Protein Identification Resource (PIR) or SeqDb protein sequence databases. Basic capabilities include (i) searches for strings of amino acids with multiple choices at a given position; (ii) searches for strings including variable-length segments and delocalized constraints; (iii) searches over subsets of a database or particular regions within each sequence (e.g. N-terminal one-third); (iv) searches involving secondary structure predictions, physicochemical characteristics, and the like; and (v) searches using aligned sequences as targets with various optional weighting schemes. The various search criteria and hits can be combined and complex targets located. Once the data are loaded into virtual memory, all occurrences in PIR release 22.0 (3.7 x 10(6) amino acids) of a given short string of amino acids (e.g. a hexamer) are found in approximately 36 s. Scrutineer can also describe the entire database, user-specified hits, user-defined regions of sequence and all hits. The source code and accompanying manual are being freely distributed.