Dispersal by bagworm larvae, Metisa plana: effects of population density, larval sex, and host plant attributes

Abstract 1. The work reported here investigated the incidence of dispersal by bagworm larvae Metisa plana (Walker) (Lepidoptera: Psychidae), a species with apterous females and winged males.
2. A mark–recapture study conducted in a plantation of oil palm revealed that a significant proportion of larvae undertakes multiple episodes of ballooning, and suggested that ballooning represents a strategy for foraging both within and between hosts.
3. Experiments conducted in a controlled cage environment indicated that increasing population density and defoliation of oil palm both promote dispersal by larvae.
4. Neonatal larvae typically remained on the host where they emerged, indicating that pupation site of late-instar females influences the distribution of their progeny, and suggesting a high level of genetic relatedness in localised bagworm populations.
5. Density-dependent dispersal may generate relatively uniform distributions of M. plana in plantations of oil palm, by simultaneously stabilising populations on heavily infested palms and redistributing larvae on lightly infested palms.
6. The rate of ballooning was greater for female than for male larvae, possibly resulting from the sex-specific impact of population density on reproductive success or from late-instar females seeking suitable oviposition sites for their future progeny.     

Quantitative traits associated with adaptation of three barley (Hordeum vulgare L) cultivars to suboptimal iron supply

A laboratory method was developed that allows determination of in situ net nitrification with high sensitivity and at high temporal resolution. Nitrate in soils is quantitatively converted into nitrous oxide under strictly anaerobic conditions in the presence of 10 kPa acetylene by the soil endogenous denitrifier population, with the N₂O detected by a gas chromatograph equipped with a ⁶³Ni electron capture detector. Thus, even low net nitrification rates, i.e. small net increases in soil nitrate concentrations can easily be detected. Comparison of results using this method with results obtained using the classical in situ incubation method (buried bag soil incubation) revealed excellent agreement. Application of the new method allowed both determination of the seasonal pattern of net nitrification as well as correlation analysis between in situ NO and N₂O flux rates and in situ net nitrification rates of the forest soils studied. Regardless of the forest site studied (spruce, spruce limed, beech), and during each year of a 3 years period (1995–1997), net nitrification varied strongly with season and was least during winter and greatest during summer. The long-term annual, mean rate of net nitrification for the untreated spruce site, the limed spruce site and the beech site were 1.54 ± 0.27 mg N kg^–1 sdw d^–1, 1.92 ± 0.23 mg N kg^–1 sdw d^–1 and 1.31 ± 0.23 mg N kg^–1 sdw d^–1, respectively. In situ rates of nitrification and NO and N₂O emission were strongly correlated for all sites suggesting that nitrification was the dominate source of NO as well as N₂O.     

Defining linkages between the GSC and NSF's LTER program: how the Ecological Metadata Language (EML) relates to GCDML and other outcomes

The Genomic Standards Consortium (GSC) invited a representative of the Long-Term Ecological Research (LTER) to its fifth workshop to present the Ecological Metadata Language (EML) metadata standard and its relationship to the Minimum Information about a Genome/Metagenome Sequence (MIGS/MIMS) and its implementation, the Genomic Contextual Data Markup Language (GCDML). The LTER is one of the top National Science Foundation (NSF) programs in biology since 1980, representing diverse ecosystems and creating long-term, interdisciplinary research, synthesis of information, and theory. The adoption of EML as the LTER network standard has been key to build network synthesis architectures based on high-quality standardized metadata. EML is the NSF-recognized metadata standard for LTER, and EML is a criteria used to review the LTER program progress. At the workshop, a potential crosswalk between the GCDML and EML was explored. Also, collaboration between the LTER and GSC developers was proposed to join efforts toward a common metadata cataloging designer's tool. The community adoption success of a metadata standard depends, among other factors, on the tools and trainings developed to use the standard. LTER's experience in embracing EML may help GSC to achieve similar success. A possible collaboration between LTER and GSC to provide training opportunities for GCDML and the associated tools is being explored. Finally, LTER is investigating EML enhancements to better accommodate genomics data, possibly integrating the GCDML schema into EML. All these action items have been accepted by the LTER contingent, and further collaboration between the GSC and LTER is expected.     

Post-fire recolonization of dominant epiphytic lichen species on Quercus hypoleucoides (Fagaceae)

Following a forest fire (27 500 ha) in 1994, post-fire recolonization of Quercus hypoeleucoides by epiphytic lichens was documented as changes in lichen cover, number of small thalli, specific factors that affected reestablishment of lichens, and modes of dispersal. Three sites in the Chiricahua Mountains (Arizona, USA) were chosen according to the severity of fire damage—unburned, moderately burned, and severely burned. From 1994 through 1997, the amount of dead lichen cover significantly increased at the moderately burned site. For the same time period, the amount of live lichen cover significantly increased at the severely burned site. Numbers of new thalli increased significantly at the severely burned site each year but only in the last year (1996–1997) for the moderately burned site. Bark texture and proximity to trees with lichens were among the most important physical factors for recolonization. The most important means of dispersal for Flavopunctelia praesignis was fragmentation. For Punctelia hypoleucites, the primary means of dispersal was spores. Increases in live lichen cover and numbers of new thalli occur faster in severely burned areas probably due to the loss of lichens on tree trunks, which provides space and a lack of competition.     

Origin of the 2-amino-2-deoxy-gluconate unit in Rhizobium leguminosarum lipid A. Expression cloning of the outer membrane oxidase LpxQ

An unusual feature of the lipid A from the plant endosymbionts Rhizobium etli and Rhizobium leguminosarum is the presence of a proximal sugar unit consisting of a 2-amino-2-deoxy-gluconate moiety in place of glucosamine. An outer membrane oxidase that generates the 2-amino-2-deoxy-gluconate unit from a glucosamine-containing precursor is present in membranes of R. leguminosarum and R. etli but not in S. meliloti or Escherichia coli. We now report the identification of a hybrid cosmid that directs the overexpression of this activity by screening 1800 lysates of individual colonies of a R. leguminosarum 3841 genomic DNA library in the host strain R. etli CE3. Two cosmids (p1S11D and p1U12G) were identified in this manner and transferred into S. meliloti, in which they also directed the expression of oxidase activity in the absence of any chromosomal background. Subcloning and sequencing of the oxidase gene on a 6.5-kb fragment derived from the approximately 20-kb insert in p1S11D revealed that the enzyme is encoded by a gene (lpxQ) that specifies a protein of 224 amino acid residues with a putative signal sequence cleavage site at position 28. Heterologous expression of lpxQ using the T7lac promoter system in E. coli resulted in the production of catalytically active oxidase that was localized in the outer membrane. A new outer membrane protein of the size expected for LpxQ was present in this construct and was subjected to microsequencing to confirm its identity and the site of signal peptide cleavage. LpxQ expressed in E. coli generates the same products as seen in R. leguminosarum membranes. LpxQ is dependent on O(2) for activity, as demonstrated by inhibition of the reaction under strictly anaerobic conditions. An ortholog of LpxQ is present in the genome of Agrobacterium tumefaciens, as shown by heterologous expression of oxidase activity in E. coli.     

Preliminary assessment of arbuscular mycorrhizal fungal diversity and community structure in an urban ecosystem

Arbuscular mycorrhizal fungal (AMF) species richness, composition, spore density and diversity indices were evaluated in the Phoenix metropolitan area, Arizona, USA at 20 sampling sites selected to represent the four predominant land-use types found in the greater urban area: urban-residential, urban non-residential, agriculture and desert. AMF spores were extracted and identified from soil samples and from trap cultures established using soil collected at each site. Data were analyzed according to land use, land-use history, soil chemistry and vegetation characteristics at each site. Current agricultural sites were associated with decreased spore densities and historically agricultural sites with decreased species richness. Overall species composition was similar to that previously reported for the Sonoran desert, but composition at each sampling site was influenced by the vegetation from which samples were collected. Sites with the highest degrees of similarity in AMF species composition were also similar to each other in native plants or land use. Conversely, sites with the lowest similarity in AMF composition were those from which the majority of samples were collected from non-mycorrhizal plants, predominately ectomycorrhizal plants or bare soil. Spores of Glomus microggregatum were most abundant in urban sites, while those of G. eburneum were most abundant in desert and agricultural sites. Further studies are needed to determine the functional implications of shifts in AMF communities in urban ecosystems, including effects on plant primary productivity.     

Management strategies of dyslipidemia in the elderly: 2005

During the past 3 years, the treatment of dyslipidemia has evolved significantly. The impact of recent trial data on management strategies in older patients is especially important, because the elderly segment of the US population continues to grow. Several clinical trials have been completed since the publication of the National Cholesterol Education Program (NCEP) Adult Treatment Panel III guidelines were published in 2001. Recent trial data strongly support the use of lipid-lowering therapy in the elderly population. Although therapeutic lifestyle changes remain highly important, supplementation with lipid-lowering therapy has been shown to reduce the risk of cardiovascular events in both primary and secondary prevention models. Compelling data noted from recent clinical trials have prompted the NCEP to publish an updated report that addresses the significant interim developments.     

Evidence-based management of acute myocardial infarction in the elderly--current perspectives

Cardiovascular disease accounts for significant morbidity and mortality in the elderly. Despite several, large cardiovascular clinical trials, data to guide therapy in this growing population subset are relatively limited. This review focuses on treatment approaches and recommendations for the management of elderly patients with acute myocardial infarction (MI) obtained from subgroup analyses from major clinical trials.Treatment options for acute MI in the elderly have changed dramatically since the 1990s. Reperfusion therapy by primary percutaneous coronary intervention has superseded the use of thrombolytic therapy for the treatment of acute ST-elevation myocardial infarction (STEMI). Clinical trial data have demonstrated that even transferring patients to facilities that have primary angioplasty capabilities is better than thrombolytic therapy, if the anticipated transfer time is of acceptable duration. Additionally, adjunctive use of the intravenous glycoprotein (GP) receptor antagonist, abciximab, during primary angioplasty affords a reduction in the composite primary end point of death, reinfarction, and target vessel revascularization, with much of the benefit derived from the latter. Thrombolytic therapy, barring any contraindication, must be used when mechanical revascularization is not available; however, the risk for complications in the elderly is higher, especially for those 75 years and older. Studies investigating the use of thrombolytics plus GP receptor antagonists with and without percutaneous coronary intervention show questionable benefit in the elderly.     

IL-4 promotes Stat6-dependent survival of autoreactive B cells in vivo without inducing autoantibody production

Persistent cross-linking of hen egg lysozyme (HEL)-specific B cell membrane Ig (mIg) in double transgenic mice that express soluble HEL as a self Ag (HEL-Ig mice) decreases B cell mIgM expression, responsiveness, and life span. Because in vitro treatment with IL-4 inhibits T cell apoptosis through a Stat6-independent mechanism, increases mIg expression, and suppresses activation-induced B cell death, we studied IL-4 effects on B cell mIg expression, survival, and Ab secretion in Stat6-sufficient and deficient HEL-Ig mice. IL-4 treatment nearly normalized B cell number and greatly increased the percentage of mature B cells in HEL-Ig mice, but failed to normalize mIgM expression or spontaneous LPS-induced IgM secretion. IL-4 effects on B cell survival and maturation were CD4(+) T cell independent, but Stat6 dependent, and did not involve receptor editing. IL-4 had to be present while B cells were generated to have a detectable effect on autoreactive B cell survival; however, the survival of B cells generated in the presence of IL-4 was substantially increased even after IL-4 was withdrawn. These observations suggest that: 1) activation-induced B cell death and anergy are independent processes; 2) B cells that survive to maturity develop increased resistance to Ag-induced deletion; and 3) IL-4 promotes B and T cell survival through different mechanisms.