Identification of two genes, sll0804 and slr1306, as putative components of the CO2-concentrating mechanism in the cyanobacterium Synechocystis sp. strain PCC 6803

Insertional transposon mutations in the sll0804 and slr1306 genes were found to lead to a loss of optimal photoautotrophy in the cyanobacterium Synechocystis sp. strain PCC 6803 grown under ambient CO₂ concentrations (350 ppm). Mutants containing these insertions (4BA2 and 3ZA12, respectively) could grow photoheterotrophically on glucose or photoautotrophically at elevated CO₂ concentrations (50,000 ppm). Both of these mutants exhibited an impaired affinity for inorganic carbon. Consequently, the Sll0804 and Slr1306 proteins appear to be putative components of the carbon-concentrating mechanism in Synechocystis sp. strain PCC 6803.     

Detection of gill-associated virus (GAV) by in situ hybridization during acute and chronic infections of Penaeus monodon and P. esculentus

Chronic and acute gill-associated virus (GAV) infections were examined by in situ hybridization (ISH) using a DNA probe targeting a 779 nucleotide region of the ORF1b-gene. Chronic GAV infections were observed in healthy Penaeus monodon collected from farms and healthy P. esculentus surviving experimental infection. During chronic-phase infections in both species, GAV was detected only in partitioned foci of cells with hypertrophied nuclei (spheroids) within the lymphoid organ. Acute-phase infections were observed in moribund P. monodon and P. esculentus infected experimentally with a high dose of GAV, and in moribund P. monodon collected from farms during outbreaks of disease. During acute experimental infections in P. monodon, ISH detected GAV throughout the lymphoid organ, in gills and in connective tissues throughout the cephalothorax. In moribund P. monodon collected from natural outbreaks of disease, GAV was also detected in the gills and in connective tissues of the cephalothorax, but the distribution of virus within the lymphoid organ varied. In acutely infected P. esculentus, GAV was detected in connective tissues, but was restricted to the inner stromal matrix cells and endothelial cells of intact lymphoid organ tubules. The tissue distribution of GAV identified by ISH suggests that shrimp are able to control and maintain chronic asymptomatic infection by a process involving lymphoid organ spheroids. Acute phase infections and the development of disease appear to be dose-related and involve the systemic distribution of virus in connective tissues throughout the cephalothorax.     

Differences in the susceptibility of some penaeid prawn species to gill-associated virus (GAV) infection

Four species of penaeid prawn cultured in Australia (Penaeus monodon, Penaeus esculentus, Marsupenaeus japonicus and Fenneropenaeus merguiensis) were injected with a virulent preparation of gill-associated virus (GAV). P. monodon (average weight = 8.9, 13.9 and 19.2 g), P. esculentus (average weight = 19.5 g), F. merguiensis (average weight = 10.5 g), and small (average weight = 5.8 g) M. japonicus displayed overt signs of disease and mortalities which reached 82 to 100% within 23 d post-injection. Cumulative mortalities in P. esculentus and F. merguiensis were significantly lower than for P. monodon of the same size class. Medium (average weight = 13.0 g) M. japonicus also developed overt signs of disease but cumulative mortalities were not significantly higher than uninfected controls. Large (average weight = 20.3 g) M. japoncius did not display symptoms of disease and there were no significant mortalities up to 23 d post-injection.     

The Wavelet-Based Cluster Analysis for Temporal Gene Expression Data

A variety of high-throughput methods have made it possible to generate detailed temporal expression data for a single gene or large numbers of genes. Common methods for analysis of these large data sets can be problematic. One challenge is the comparison of temporal expression data obtained from different growth conditions where the patterns of expression may be shifted in time. We propose the use of wavelet analysis to transform the data obtained under different growth conditions to permit comparison of expression patterns from experiments that have time shifts or delays. We demonstrate this approach using detailed temporal data for a single bacterial gene obtained under 72 different growth conditions. This general strategy can be applied in the analysis of data sets of thousands of genes under different conditions.[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]