Phylogenetics and evolution of nematode-trapping fungi (Orbiliales) estimated from nuclear and protein coding genes

The systematic classification of nematode-trapping fungi is redefined based on phylogenies inferred from sequence analyses of 28S rDNA, 5.8S rDNA and beta-tubulin genes. Molecular data were analyzed with maximum parsimony, maximum likelihood and Bayesian analysis. An emended generic concept of nematode-trapping fungi is provided. Arthrobotrys is characterized by adhesive networks, Dactylellina by adhesive knobs, and Drechslerella by constricting-rings. Phylogenetic placement of taxa characterized by stalked adhesive knobs and non-constricting rings also is confirmed in Dactylellina. Species that produce unstalked adhesive knobs that grow out to form loops are transferred from Gamsylella to Dactylellina, and those that produce unstalked adhesive knobs that grow out to form networks are transferred from Gamsylella to Arthrobotrys. Gamsylella as currently circumscribed cannot be treated as a valid genus. A hypothesis for the evolution of trapping-devices is presented based on multiple gene data and morphological studies. Predatory and nonpredatory fungi appear to have been derived from nonpredatory members of Orbilia. The adhesive knob is considered to be the ancestral type of trapping device from which constricting rings and networks were derived via two pathways. In the first pathway adhesive knobs retained their adhesive material forming simple two-dimension networks, eventually forming complex three-dimension networks. In the second pathway adhesive knobs lost their adhesive materials, with their ends meeting to form nonconstricting rings and they in turn formed constricting rings with three inflated-cells.     

Verification of a European corn borer (Lepidoptera: Crambidae) loss equation in the major corn production region of the northeastern United States

Field studies in Pennsylvania and Maryland were conducted during 2000, 2001, and 2002 to test the applicability of published yield loss relationships developed in central Pennsylvania for European corn borer, Ostrinia nubilalis (Hübner), management in warmer, longer season corn, Zea mays L., grain production regions of the northeastern United States. Both isoline hybrids and non-Bt lead hybrids were compared against Bacillus thuringiensis (Bt) hybrids to measure effects of the pest on yield. The European corn borer economic analysis model was used to make site-specific predictions of loss per European corn borer larva for comparison with measured yield loss per larva. Although the model did not predict loss per larva at a field level, it did predict loss at a regional level. The model predicted an overall percentage of yield loss per larva of 2.69+/-0.12% over the region, which was similar to the measured yield loss per larva of 2.66+/-0.59% for isoline hybrids and 3.08+/-0.51% for lead hybrids. The model, on average, provided a good prediction of percentage of yield loss per larva within the climatic zones of 1100-1700 degree-days (DD) (base threshold 12.5 degrees C). Our results suggest that the yield loss relationship developed in Central Pennsylvania, when matched to the timing of third instar second generation European corn borer stalk tunneling is adequate for major corn grain production zones of the northeast United States.     

Spatial and bathymetric trends in Harpacticoida (Copepoda) community structure in the Northern Gulf of Mexico deep-sea

Harpacticoid copepod community structure was analyzed at 43 stations in the northern Gulf of Mexico deep-sea to test regional and bathymetric patterns of diversity in relation to environmental variables and topographic complexity of the continental slope. Depth, longitude, and proximity to the Florida Escarpment significantly affect average phylogenetic diversity, but basins and canyons do not. Multivariate analysis reveals a significant inverse relationship between diversity and POM flux, which is confirmed by significant region-scale depth and longitude differences. Although species richness declines linearly with increasing depth, the expected number of species (rarefraction) is maximized at approximately 1200 m, and average taxonomic and phylogenetic diversity continue to increase with depth, suggesting greater morphological or functional harpacticoid diversity with increasing depth. Most stations have unique species compositions, suggesting high regional (2200 species) and global (10⁵-10⁶ species) diversity by extrapolation. Therefore, processes maintaining harpacticoid diversity in the northern Gulf of Mexico deep-sea seem to rely on both small-scale dispersal and large-scale food supply mechanisms.     

Low-diversity fungal assemblage in an Antarctic Dry Valleys soil

The McMurdo Dry Valleys of Antarctica present extreme environmental challenges. Life is restricted to patchy occurrence of lichens, mosses and invertebrates, plus soil microbial communities. Fungi have been described in lichen symbioses but relatively little is known about the occurrence of free-living soil fungi in the Dry Valleys. A challenge in estimating fungal species richness has been the extent to which estimates based on either cultivation or environmental DNA reflect the active assemblage in cold-arid soils. Here, we describe analysis for inland Dry Valleys soil of environmental DNA and RNA (cDNA) to infer total and putative metabolically active assemblages, respectively, plus cultivation approaches using a variety of laboratory growth conditions. Environmental sequences indicated a highly restricted assemblage of just seven phylotypes that affiliated phylogenetically within two known genera, Helicodendron and Zalerion, plus previously unidentified fungal phylotypes. None of the commonly encountered molds and mitosporic genera recorded from maritime Antarctic locations were encountered. A striking difference was observed in the frequency of recovery for phylotypes between libraries. This suggests that both species richness and beta diversity estimates based on DNA libraries have the potential to misinform putatively active assemblages. Cultivation yielded a cold-tolerant Zalerion strain that affiliated with DNA and RNA library clones, and a psychrotrophic yeast (Debaryomyces hansenii), which was not detected using either culture-independent approach.     

Thermal acclimation,heat shock and photoperiod: Do these factors interplay in the adaptive responses of crab neuromuscular systems to temperature?

Evidence is reviewed demonstrating that the adaptive responses to temperature made by the walking leg neuromuscular system of crabs (Carcinus maenas) are in response to local temperature and not in response to hierarchical influences by the CNS and hormonal systems.     

Comparative population genetic analysis of bocaccio rockfish Sebastes paucispinis using anonymous and gene-associated simple sequence repeat loci

Comparative population genetic analyses of traditional and emergent molecular markers aid in determining appropriate use of new technologies. The bocaccio rockfish Sebastes paucispinis is a high gene-flow marine species off the west coast of North America that experienced strong population decline over the past 3 decades. We used 18 anonymous and 13 gene-associated simple sequence repeat (SSR) loci (expressed sequence tag [EST]-SSRs) to characterize range-wide population structure with temporal replicates. No F(ST)-outliers were detected using the LOSITAN program, suggesting that neither balancing nor divergent selection affected the loci surveyed. Consistent hierarchical structuring of populations by geography or year class was not detected regardless of marker class. The EST-SSRs were less variable than the anonymous SSRs, but no correlation between F(ST) and variation or marker class was observed. General linear model analysis showed that low EST-SSR variation was attributable to low mean repeat number. Comparative genomic analysis with Gasterosteus aculeatus, Takifugu rubripes, and Oryzias latipes showed consistently lower repeat number in EST-SSRs than SSR loci that were not in ESTs. Purifying selection likely imposed functional constraints on EST-SSRs resulting in low repeat numbers that affected diversity estimates but did not affect the observed pattern of population structure.     

Mitochondrial fusion, fission and autophagy as a quality control axis: the bioenergetic view

The mitochondrial life cycle consists of frequent fusion and fission events. Ample experimental and clinical data demonstrate that inhibition of either fusion or fission results in deterioration of mitochondrial bioenergetics. While fusion may benefit mitochondrial function by allowing the spreading of metabolites, protein and DNA throughout the network, the functional benefit of fission is not as intuitive. Remarkably, studies that track individual mitochondria through fusion and fission found that the two events are paired and that fusion triggers fission. On average each mitochondrion would go though ~5 fusion:fission cycles every hour. Measurement of Deltapsi(m) during single fusion and fission events demonstrates that fission may yield uneven daughter mitochondria where the depolarized daughter is less likely to become involved in a subsequent fusion and is more likely to be targeted by autophagy. Based on these observations we propose a mechanism by which the integration of mitochondrial fusion, fission and autophagy forms a quality maintenance mechanism. According to this hypothesis pairs of fusion and fission allow for the reorganization and sequestration of damaged mitochondrial components into daughter mitochondria that are segregated from the networking pool and then becoming eliminated by autophagy.     

Microfungi on the Pandanaceae: a revision of the hyphomycete genus Balaniopsis with two new species

During research into microfungi that inhabit decaying parts of the monocotyledonous family Pandanaceae, three species of Balaniopsis were collected. One is Balaniopsis africana as originally described and illustrated by Kiffer as Balanium africanum. The second species is conspecific with the specimen treated as Balaniopsis africana by Kirk, but is introduced here as a new species, Balaniopsis kirkii. The third, Balaniopsis dendroidea, is a new species from Australia. Received: March 21, 2001 / Accepted: October 8, 2001