We report the complete sequence of the 4,274,642-bp genome of Haloarcula marismortui, a halophilic archaeal isolate from the Dead Sea. The genome is organized into nine circular replicons of varying G+C compositions ranging from 54% to 62%. Comparison of the genome architectures of Halobacterium sp. NRC-1 and H. marismortui suggests a common ancestor for the two organisms and a genome of significantly reduced size in the former. Both of these halophilic archaea use the same strategy of high surface negative charge of folded proteins as means to circumvent the salting-out phenomenon in a hypersaline cytoplasm. A multitiered annotation approach, including primary sequence similarities, protein family signatures, structure prediction, and a protein function association network, has assigned putative functions for at least 58% of the 4242 predicted proteins, a far larger number than is usually achieved in most newly sequenced microorganisms. Among these assigned functions were genes encoding six opsins, 19 MCP and/or HAMP domain signal transducers, and an unusually large number of environmental response regulators-nearly five times as many as those encoded in Halobacterium sp. NRC-1-suggesting H. marismortui is significantly more physiologically capable of exploiting diverse environments. In comparing the physiologies of the two halophilic archaea, in addition to the expected extensive similarity, we discovered several differences in their metabolic strategies and physiological responses such as distinct pathways for arginine breakdown in each halophile. Finally, as expected from the larger genome, H. marismortui encodes many more functions and seems to have fewer nutritional requirements for survival than does Halobacterium sp. NRC-1.

To better understand the extremely halophilic archaeon Halobacterium species NRC-1, we analyzed its soluble proteome by two-dimensional liquid chromatography coupled to electrospray ionization tandem mass spectrometry. A total of 888 unique proteins were identified with a ProteinProphet probability (P) between 0.9 and 1.0. To evaluate the biochemical activities of the organism, the proteomic data were subjected to a biological network analysis using our BMSorter software. This allowed us to examine the proteins expressed in different biomodules and study the interactions between pertinent biomodules. Interestingly an integrated analysis of the enzymes in the amino acid metabolism and citrate cycle networks suggested that up to eight amino acids may be converted to oxaloacetate, fumarate, or oxoglutarate in the citrate cycle for energy production. In addition, glutamate and aspartate may be interconverted from other amino acids or synthesized from citrate cycle intermediates to meet the high demand for the acidic amino acids that are required to build the highly acidic proteome of the organism. Thus this study demonstrated that proteome analysis can provide useful information and help systems analyses of organisms. Halobacterium species NRC-1 is an extremely halophilic archaeon containing a highly acidic proteome with a median pI of 4.9, a property that is essential to the maintenance of the solubility and function of the proteins in a high salinity environment of about 5 M salts (1, 2). Genome sequence analysis has revealed 2,630 putative protein-coding genes in the 2,571,010-bp genome (2). Among the predicted proteins, 1,658 can be matched to sequences in public databases. Of the matches, 1,067 are proteins of known or predicted function, and 591 are proteins of unknown function. The possession of a relatively small and completely sequenced genome, the availability of a full arsenal of genetic manipulation tools, and the relative ease of culture make Halobacterium sp. NRC-1 an attractive systems biology model organism of the domain Archaea (3-6).The genomes of Halobacterium species are extremely unstable (7-9). Early studies of Halobacterium sp. NRC-1 (also known as Halobacterium halobium) and the closely related Halobacterium salinarium discovered unusually high spontaneous mutation frequencies of 0.01% for the production of bacteriorhodopsin-or bacterioruberin-deficient phenotypes and a more striking 1% for partial or total gas vesicle-deficient phenotypes. The species is also noteworthy for the large number of insertion sequence elements that are harbored in this unstable genome. Molecular genetic analysis of the bacteriorhodopsin-and gas vesicle-deficient mutants established a relationship between transposable insertion sequence-mediated insertional inactivation or deletions of structural or regulatory genes and the high mutant rates (10 -16). Upon the completion of the genome sequence, DNA analysis revealed the presence of 91 copies of insertion sequence elements belonging to 12 families in the Halobacteri...

Angiostrongylus cantonensis is an important zoonotic nematode. It is the causative agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. However, information of this parasite at the genomic level is very limited. In the present study, the transcriptomic profiles of the fifth-stage larvae (L5) of A. cantonensis were investigated by next-generation sequencing (NGS). In the NGS database established from the larvae isolated from the brain of Sprague–Dawley rats, 31,487 unique genes with a mean length of 617 nucleotides were assembled. These genes were found to have a 46.08 % significant similarity to Caenorhabditis elegans by BLASTx. They were then compared with the expressed sequence tags of 18 other nematodes, and significant matches of 36.09–59.12 % were found. Among these genes, 3,338 were found to participate in 124 Kyoto Encyclopedia of Genes and Genomes pathways. These pathways included 1,514 metabolisms, 846 genetic information processing, 358 environmental information processing, 264 cellular processes, and 91 organismal systems. Analysis of 30,816 sequences with the gene ontology database indicated that their annotations included 5,656 biological processes (3,364 cellular processes, 3,061 developmental processes, and 3,191 multicellular organismal processes), 7,218 molecular functions (4,597 binding and 3,084 catalytic activities), and 4,719 cellular components (4,459 cell parts and 4,466 cells). Moreover, stress-related genes (112 heat stress and 33 oxidation stress) and genes for proteases (159) were not uncommon. This study is the first NGS-based study to set up a transcriptomic database of A. cantonensis L5. The results provide new insights into the survival, development, and host–parasite interactions of this blood-feeding nematode.Electronic supplementary materialThe online version of this article (doi:10.1007/s00436-013-3495-z) contains supplementary material, which is available to authorized users.