Effects of latitude on the competitive ability of native and invasive genotypes of Phragmites australis

One commonly cited mechanism for the success of invasive species is their superior competitive ability relative to that of native species. Although 88% (22 of 25) of the empirical studies support the prediction that the strength of competition for native species increases with latitude, no studies to date have compared the competitive ability of native and co-occurring invasive species across a broad latitudinal range. In a greenhouse, I investigated whether the competitive ability of North American native and European invasive haplotypes of Phragmites australis vary with latitude. Another widespread, non-indigenous haplotype, the Gulf Coast haplotype, was also included for assessment of competitive ability only. Competitive ability of each haplotype was evaluated against a standardized plant species, Spartina alterniflora, which is a common co-inhabitant of coastal marshes. The competitive ability (measured in terms of the proportional reduction in biomass of plants grown in the presence and absence of a potential competitor) of native haplotypes decreased with increasing latitude, whereas the competitive ability of invasive haplotypes showed no relationship with latitude. This study provided the first evidence that native and invasive species (or haplotypes) exhibit non-parallel gradients in competitive ability. Overall, the invasive haplotype was competitively superior to the native haplotype - biomass production of S. alterniflora was 19% lower when grown with the former than the latter haplotype. Moreover, in the presence of an interspecific competitor, the invasive haplotype produced 45% more aboveground biomass and 50% more belowground biomass than the native haplotype. Results also indicated that the Gulf Coast haplotype was not significantly different from either the native or invasive haplotypes in terms of competitive ability. Because the invasive haplotype appeared to have the greatest competitive advantage over the natives at northern latitudes, it may be more successful in this region of its invaded range. The results from this research indicate that novel and important findings are possible when the mechanisms concerning invasion success, such as biotic resistance and competition, are examined from a biogeographical perspective

Linking Innate and Adaptive Immunity: Human Vγ9Vδ2 T Cells Enhance CD40 Expression and HMGB-1 Secretion

γδ T cells play an important role in regulating the immune response to stress stimuli; however, the mean by which these innate lymphocytes fulfill this function remains poorly defined. The main subset of human peripheral blood γδ T cells responds to nonpeptidic antigens, such as isopentylpyrophosphate (IPP), a metabolite in the mevalonate pathway for both eukaryote and prokaryote cells. IPP-primed γδ T cells significantly augment the inflammatory response mediated by monocytes and αβ T cells to TSST-1, the staphylococcal superantigen that is the major causative agent of toxic shock syndrome. Here we show that the small pool of activated peripheral γδ T cells induces an early upregulation of CD40 on monocytes and the local release of High Mobility Group Box-1 (HMGB-1), the molecule designated as the late mediator of systemic inflammation. This finding provides a new basis for how γδ T cells may serve as influential modulators of both endogenous and exogenous stress stimuli

Staphylococcal Toxic Shock Syndrome Toxin-1 Induces the Translocation and Secretion of High Mobility Group-1 Protein from Both Activated T Cells and Monocytes

High mobility group box-1 (HMGB-1) is a DNA-binding protein secreted by activated monocytes and has been identified as a key late mediator of endotoxic shock. We investigated the regulation of HMGB-1 in human peripheral blood mononuclear cells (PBMCs) following stimulation with the staphylococcal superantigen, toxic shock syndrome toxin-1 (TSST-1), and found that TSST-1, like LPS, induced the secretion of HMGB-1 from human PBMC. However, unlike monocyte-driven sepsis caused by endotoxin, translocation and secretion of HMGB-1 mediated by TSST-1 was dependent on the presence of both activated T cells and monocytes. Furthermore, we show that nuclear HMGB-1 is released from TSST-1 stimulated T cells. This finding presents a basis for investigating the potential of targeting HMGB-1 for the treatment of toxic shock syndrome, and provides further insight on the role of HMGB-1 in the cross-talk between activated monocytes and T cells

A catalyst for educational change: the role of career and technical education in Georgia’s statewide educational improvement efforts

The Central Educational Center is a product of multiple visions, desires, and hopes. The ideal vision is outlined in a book entitled “The Eden Conspiracy” (Harless, 1997). Other perspectives include a requirement from local business that basic skills of high school graduates need to be rapidly improved, the desire of a growing local school system to provide costly industry-standard career-technical education to all high school students, the vision of a regional technical college to “dual enroll” high school students and make technical college a viable post-secondary option, and the hopes of a Governor looking for a viable model to support his desire to reform education partly through a new infusion of technical education opportunities

Cellulase production by the Thermophilic Fungus, Thermoascus aurantiacus

Thermoascus aurantiacus was the most active cellulase producer of several thermphilic fungi tested. The optimum growth temperature for T. aurantiacus in liquid medium was 45° C and maximum cellulase production from filter paper occurred at 40°C. The optimum temperatue for {3-glucosidase and carboxymethylcellulase activity was 70° C; for filter paper degrading activity it was 65°C. Maximum activity was found at pH 5.0 for the filter paper degrading enzyme and glucosidase and pH 4.3 for carboxymethylcellulase activity

Fast optical layer mesh protection using pre-cross-connected trails

Conventional optical networks are based on SONET rings, but since rings are known to use bandwidth inefficiently, there has been much research into shared mesh protection, which promises significant bandwidth savings. Unfortunately, most shared mesh protection schemes cannot guarantee that failed traffic will be restored within the 50 ms timeframe that SONET standards specify. A notable exception is the p-cycle scheme of Grover and Stamatelakis. We argue, however, that p-cycles have certain limitations, e.g., there is no easy way to adapt p-cycles to a path-based protection scheme, and p-cycles seem more suited to static traffic than to dynamic traffic. In this paper we show that the key to fast restoration times is not a ring-like topology per se, but rather the ability to pre-cross-connect protection paths. This leads to the concept of a pre-cross-connected trail or PXT, which is a structure that is more flexible than rings and that adapts readily to both path-based and link-based schemes and to both static and dynamic traffic. The PXT protection scheme achieves fast restoration speeds, and our simulations, which have been carefully chosen using ideas from experimental design theory, show that the bandwidth efficiency of the PXT protection scheme is comparable to that of conventional shared mesh protection schemes.Comment: Article has appeared in IEEE/ACM Trans. Networkin