Hydrogenosomes, membrane-bounded organelles that compartmentalize the terminal reactions of cellular energy metabolism, were first described in the parabasalid flagellate Tritrichomonas foetus as subcellular compartments that produce hydrogen and ATP (adenosine triphosphate). Since then, these organelles have been described in a number of different unicellular eukaryotes adapted to microaerobic or anoxic environments. Recent studies have led researchers to consider hydrogenosomes as variations of mitochondria adapted to anaerobic environments, a concept that is supported by the finding of rudimentary mitochondrial-remnant organelles in organisms previously considered devoid of energy-generating organelles (the Archezoa). The relationship of these energy-generating organelles to each other and to the mitochondrion has been examined by many researchers, and several theories have been put forward to explain their origins. In this article, we hope to correct some misconceptions concerning the relationships of the hydrogenosomes so far described, and to put forward an argument that supports the concept that hydrogenosomes evolved repeatedly, either from a protomitochondrion or from differentiated mitochondria.

Within the next few years, many types of transgenic rice ( Oryza sativa ) will be ready for commercialization, including varieties with higher yields, greater tolerance of biotic and abiotic stresses, resistance to herbicides, improved nutritional quality, and novel pharmaceutical proteins. Although rice is primarily self-pollinating, its transgenes are expected to disperse to nearby weedy and wild relatives through pollen-mediated gene flow. Sexually compatible Oryza species often co-occur with the crop, especially in tropical countries, but little is known about how quickly fitness-enhancing transgenes will accumulate in these populations and whether this process will have any unwanted environmental consequences. For example, weedy rice could become much more difficult to manage if it acquires herbicide resistance, produces more seeds, or occurs in a wider range of habitats because of the spread of certain transgenes. Rice-growing countries urgently need publicly available ecological assessments of the risks and benefits of transgenic rice before new varieties are released.

The interaction between plants and their pathogens is complex. Plant pathogens have evolved a broad set of proteins that enable a stealthy entry into the plant cell and facilitate the evasion of host defenses. Among other defenses, plants have evolved a series of proteins that monitor their cells for signs of infection. Downstream of these monitors is a signaling and response system triggered upon infection. The molecular basis of the host–pathogen interaction is now much better understood, as a result of the development of genomic data and tools. For example, the complete genomic sequence is available for a model plant, Arabidopsis, and for one of its bacterial pathogens, Pseudomonas syringae pv. tomato DC3000. Detailed molecular analyses of these two organisms have revealed much about plant defenses. Modern genomics tools, including applications of bioinformatics and functional genomics, allow scientists to interpret DNA sequence data and test hypotheses on a broader scale than previously possible.

The increasing number of scientific publications has made bibliographic search engines essential tools in all disciplines. These software-based devices, however, are far from perfect. Comparisons of software-based bibliographic search engines with complete lists of three authors' publications showed that reference citations were not generally available before 1970, and that the effectiveness of recovery was improving but was quite variable, yielding on average 36 percent of the publications. There was marked year-to-year inconsistency in the recovery of titles. The inconsistency could not be explained by differences in indexing due to journal reputation: there was no evident relationship between search effectiveness and journal impact factor, but the percentage of recovered citations was higher for indexed journals. Search engines are widely used in bibliographic searches performed for evaluating researchers, awarding promotions, or assessing journal performance. Given the ineffectiveness of search engines, their use in making such important personal and institutional decisions needs careful consideration.

Amphibians are characterized both by a strongly increasing number of newly discovered species and by a high degree of decline. The observed increase in species numbers, over 25 percent in 11 years, is largely due to the intensified exploration of tropical areas and the application of more efficient techniques such as bioacoustics and molecular genetics, rather than to the elevation of subspecies to species rank or the distinction of species that were formerly considered synonymous. In the mantellid frogs of Madagascar, the many species newly described between 1992 and 2004 were as genetically divergent as those described in previous research periods, and most had not been collected previously, corroborating the lack of “taxonomic inflation” in this vertebrate class. Taxonomic exploration is still desperately needed to avoid misinterpretations in global conservation policy.