Photosynthesis and the Web: 2001

First, a brief history of the Internet and the World Wide Web is presented. This is followed by relevant information on photosynthesis-related web sites grouped into several categories: (1) large group sites, (2) comprehensive overview sites, (3) specific subject sites, (4) individual researcher sites, (5) kindergarten through high school (K-12) educational sites, (6) books and journals, and, 7) other useful sites. A section on searching the Web is also included. Finally, we have included an appendix with all of the web sites discussed herein as well as other web sites that space did not allow. Readers are requested to send comments, corrections and additions to gov@uiuc.edu. This revised version was published online in June 2006 with corrections to the Cover Date.     

Trichogramma releases in North Carolina cotton: why releases fail to suppress heliothine pests

Field studies were conducted in 1996 and 1997 to determine the fate of naturally oviposited F3 heliothine eggs in cotton plots treated with augmentative releases of Trichogramma exiguum Pinto & Platner and nontreated plots. Four cohorts of newly oviposited eggs (< 24 h old) were followed in 1996 and two cohorts in 1997. In 1996, mean +/- SD percent parasitism, estimated by in-field studies following the fate of naturally oviposited eggs, ranged from 7 +/- 7 to 61 +/- 8% in T. exiguum release plots and 0 +/- 0 to 35 +/- 13% in control plots. The mean +/- SD percent of eggs hatched in T. exiguum release plots ranged from 1 +/- 2 to 11 +/- 4% and 7 +/- 4 to 28 +/- 10% in control plots. In 1997, mean +/- SD percent egg parasitism ranged from 27 +/- 4 to 40 +/- 3% in T. exiguum release plots and 15 +/- 18 to 25 +/- 8% in control plots. The mean +/- SD percent of eggs hatched in T. exiguum release plots ranged from 7 +/- 3 to 12 +/- 2% and 18 +/- 6 to 28 +/- 8% in control plots. Despite increased parasitism and reduced egg hatch in T. exiguum release plots, overall, there was no significant difference in larval density (all instars combined) between T. exiguum release and control plots. Combined analysis of the heliothine larval populations and egg fate data revealed that the additional egg mortality produced by released T. exiguum was offset by lower larval mortality in release plots. Because of the occurrence of compensatory mortality, the egg stage of heliothines is not an appropriate target for biological control using Trichogramma wasp releases.     

Genetic analysis of the hybrid male rescue locus of Drosophila

Several hybrid rescue mutations-alleles that restore the viability of normally lethal hybrids-have been discovered in Drosophila melanogaster and its relatives. Here we analyze one of these genes, Hybrid male rescue (Hmr), asking two questions about its role in hybrid inviability. (1) Does the wild-type allele from D. melanogaster (Hmr(mel)) cause hybrid embryonic inviability? (2) Does Hmr(mel) cause hybrid larval inviability? Our results show that the wild-type product of Hmr is neither necessary nor sufficient for hybrid embryonic inviability. Hmr(mel) does, however, appear to lower the viability of hybrid larvae. The data further suggest (though do not prove) that Hmr(mel) acts as a gain-of-function poison in hybrids. These findings support previous claims that hybrid embryonic and larval lethalities are genetically distinct and suggest that Hmr(mel) is at least one of the proximate causes of hybrid larval inviability.     

Penetration of the coral-bleaching bacterium Vibrio shiloi into Oculina patagonica

Inoculation of the coral-bleaching bacterium Vibrio shiloi into seawater containing its host Oculina patagonica led to adhesion of the bacteria to the coral surface via a beta-D-galactose receptor, followed by penetration of the bacteria into the coral tissue. The internalized V. shiloi cells were observed inside the exodermal layer of the coral by electron microscopy and fluorescence microscopy using specific anti-V. shiloi antibodies to stain the intracellular bacteria. At 29 degrees C, 80% of the bacteria bound to the coral within 8 h. Penetration, measured by the viable count (gentamicin invasion assay) inside the coral tissue, was 5.6, 20.9, and 21.7% of the initial inoculum at 8, 12, and 24 h, respectively. The viable count in the coral tissue decreased to 5.3% at 48 h, and none could be detected at 72 h. Determination of V. shiloi total counts (using the anti-V. shiloi antibodies) in the coral tissue showed results similar to viable counts for the first 12 h of infection. After 12 h, however, the total count more than doubled from 12 to 24 h and continued to rise, reaching a value 6 times that of the initial inoculum at 72 h. Thus, the intracellular V. shiloi organisms were transformed into a form that could multiply inside the coral tissue but did not form colonies on agar medium. Internalization of the bacteria was accompanied by the production of high concentrations of V. shiloi toxin P activity in the coral tissue. Internalization and multiplication of V. shiloi are discussed in terms of the mechanism of bacterial bleaching of corals.     

Combining regression trees and radial basis function networks

We describe a method for non-parametric regression which combines regression trees with radial basis function networks. The method is similar to that of Kubat, who was first to suggest such a combination, but has some significant improvements. We demonstrate the features of the new method, compare its performance with other methods on DELVE data sets and apply it to a real world problem involving the classification of soybean plants from digital images.     

Trypanosoma cruzi: stage expression of calmodulin-binding proteins.

The subcellular distribution of calmodulin-binding proteins in three life stages of Trypanosoma cruzi was analyzed by a [125I]calmodulin gel overlay procedure under conditions where proteolysis was kept to a minimum. It was found that T. cruzi contains a complex profile of calcium-dependent calmodulin-binding proteins and that several of these polypeptides were differentially expressed at specific stages of development. The majority of these stage-specific polypeptides was found in the particulate fractions of the replicative stages of the parasite, i.e., epimastigote and amastigote. These studies suggest that calcium and calmodulin may play an important central role in the growth and differentiation of this parasite. We have also assessed the calmodulin content of the various life stages by immunoblot analysis. These studies identified a 14-kDa immunoreactive peptide present at equivalent levels in epi-, trypo-, and amastigote stages (extracellular).     

Analysis of inflorescence organogenesis in eastern gamagrass, Tripsacum dactyloides (Poaceae): the wild type and the gynomonoecious gsf1 mutant

Inflorescence organogenesis of a wild-type and a gynomonoecious (pistillate) mutant in Tripsacum dactyloides was studied using scanning electron microscopy. SEM (scanning electron microscope) analysis indicated that wild-type T. dactyloides (Eastern gamagrass) expressed a pattern of inflorescence organogenesis that is observed in other members of the subtribe Tripsacinae (Zea: maize and teosinte), family Poaceae. Branch primordia are initiated acropetally along the rachis of wild-type inflorescences in a distichous arrangement. Branch primordia at the base of some inflorescences develop into long branches, which themselves produce an acropetal series of distichous spikelet pair primordia. All other branch primordia function as spikelet pair primordia and bifurcate into pedicellate and sessile spikelet primordia. In all wild-type inflorescences development of the pedicellate spikelets is arrested in the proximal portion of the rachis, and these spikelets abort, leaving two rows of solitary sessile spikelets. Organogenesis of spikelets and florets in wild-type inflorescences is similar to that previously described in maize and the teosintes. Our analysis of gsf1 mutant inflorescences reveals a pattern of development similar to that of the wild type, but differs from the wild type in retaining (1) the pistillate condition in paired spikelets along the distal portion of the rachis and (2) the lower floret in sessile spikelets in the proximal region of the rachis. The gsf1 mutation blocks gynoecial tissue abortion in both the paired-spikelet and the unpaired-spikelet zone. This study supports the hypothesis that both femaleness and maleness in Zea and Tripsacum inflorescences are derived from a common developmental pathway. The pattern of inflorescence development is not inconsistent with the view that the maize ear was derived from a Tripsacum genomic background.     

Rat coagulating gland secretion contains a kinesin heavy chain-like protein acting as a type IV transglutaminase substrate

By a proteomic approach, we demonstrated in rat coagulating gland secretion the presence of a 120 kDa protein which shares at least 80% identity at the amino acid level with the most closely related kinesin heavy chain codified by the kinesin superfamily protein Kif5c gene. In addition, we identified 30 and 66 kDa proteolytic fragments of such a kinesin heavy chain-like protein, corresponding to the 73-299 N-terminal and 300-860 C-terminal regions, respectively. Finally, we demonstrated the occurrence in coagulating gland secretion of a 200 kDa protein probably derived by cross-linking reaction of the kinesin heavy chain-like protein with type IV transglutaminase. In fact, kinesin heavy chain-like protein and its 66 kDa proteolytic fragment were also found to act as effective acyl donor substrates for the enzyme in vitro.     

Phylogeny-based assignment of functional traits to DNA barcodes outperforms distance-based,in a comparison of approaches

The full potential for using DNA barcodes for profiling functional trait diversity has yet to be determined in plants and animals; thus, we outline a general framework for quantifying functional trait diversity of insect community DNA and propose and assess the accuracy of three methods for achieving this. We built a novel dataset of traits and DNA barcodes for wild bees in China. An informatics framework was developed for phylogeny-based integration of these data and prediction of traits for any subject barcodes, which was compared with two distance-based methods. For Phylogenetic Assignment, we additionally conducted a species-level analysis of publically available bee trait data. Under the specimen-level dataset, the rate of trait assignment was negatively correlated with distance between the query and the nearest trait-known reference, for all methods. Phylogenetic Assignment was found to perform best under several criteria; particularly, it had the lowest false-positive rate (rarely returning a state prediction where success was unlikely; where the distance from query to the nearest reference was high). For a wider range of compiled traits, conservative life-history traits showed the highest rates of assignment; for example, sociality was predicted with confidence at 53%, parasitism at 44% and nest location at 33%. As outlined herein, automated trait assignment might be applied at scale to either barcodes or metabarcodes. With further compilation and databasing of DNA barcode and trait data, the rate and accuracy of trait assignment is expected to increase to the point of being a widely viable and informative approach.