Effective Competitor Research Articles

Incorporation of albumin fusion proteins into fibrin clots in vitro and in vivo: comparison of different fusion motifs recognized by factor XIIIa

BackgroundThe transglutaminase activated factor XIII (FXIIIa) acts to strengthen pathological fibrin clots and to slow their dissolution, in part by crosslinking active α2-antiplasmin (α2AP) to fibrin. We previously reported that a yeast-derived recombinant fusion protein comprising α2AP residues 13-42 linked to human serum albumin (HSA) weakened in vitro clots but failed to become specifically incorporated into in vivo clots. In this study, our aims were to improve both the stability and clot localization of the HSA fusion protein by replacing α2AP residues 13-42 with shorter sequences recognized more effectively by FXIIIa.ResultsExpression plasmids were prepared encoding recombinant HSA with the following N-terminal 23 residue extensions: H6NQEQVSPLTLLAG4Y (designated XL1); H6DQMMLPWAVTLG4Y (XL2); H6WQHKIDLPYNGAG4Y (XL3); and their 17 residue non-His-tagged equivalents (XL4, XL5, and XL6). The HSA moiety of XL4- to XL6-HSA proteins was C-terminally His-tagged. All chimerae were efficiently secreted from transformed Pichia pastoris yeast except XL3-HSA, and following nickel chelate affinity purification were found to be intact by amino acid sequencing, as was an N-terminally His-tagged version of α2AP(13-42)-HSA. Of the proteins tested, XL5-HSA was cross-linked to biotin pentylamine (BPA) most rapidly by FXIIIa, and was the most effective competitor of α2AP crosslinking not only to BPA but also to plasma fibrin clots. In the mouse ferric chloride vena cava thrombosis model, radiolabeled XL5-HSA was retained in the clot to a greater extent than recombinant HSA. In the rabbit jugular vein stasis thrombosis model, XL5-HSA was also retained in the clot, in a urea-insensitive manner indicative of crosslinking to fibrin, to a greater extent than recombinant HSA.ConclusionsFusion protein XL5-HSA (DQMMLPWAVTLG4Y-HSAH6) was found to be more active as a substrate for FXIIIa-mediated transamidation than seven other candidate fusion proteins in vitro. The improved stability and reactivity of this chimeric protein was further evidenced by its incorporation into in vivo clots formed in thrombosis models in both mice and rabbits.

Competition among Hfq‐binding small RNAs in Escherichia coli

A major class of small bacterial RNAs (sRNAs) regulate translation and mRNA stability by pairing with target mRNAs, dependent upon the RNA chaperone Hfq. Hfq, related to the Lsm/Sm families of splicing proteins, binds the sRNAs and stabilizes them in vivo and stimulates pairing with mRNAs in vitro. Although Hfq is abundant, the sRNAs, when induced, are similarly abundant. Therefore, Hfq may be limiting for sRNA function. We find that, when overexpressed, a number of sRNAs competed with endogenous sRNAs for binding to Hfq. This correlated with lower accumulation of the sRNAs (presumably a reflection of the loss of Hfq binding), and lower activity of the sRNAs in regulating gene expression. Hfq was limiting for both positive and negative regulation by the sRNAs. In addition, deletion of the gene for an expressed and particularly effective competitor sRNA improved the regulation of genes by other sRNAs, suggesting that Hfq is limiting during normal growth conditions. These results support the existence of a hierarchy of sRNA competition for Hfq, modulating the function of some sRNAs.

Climate Change and American Bullfrog Invasion: What Could We Expect in South America?

BackgroundBiological invasion and climate change pose challenges to biodiversity conservation in the 21st century. Invasive species modify ecosystem structure and functioning and climatic changes are likely to produce invasive species' range shifts pushing some populations into protected areas. The American Bullfrog (Lithobates catesbeianus) is one of the hundred worst invasive species in the world. Native from the southeast of USA, it has colonized more than 75% of South America where it has been reported as a highly effective predator, competitor and vector of amphibian diseases.Methodology/Principal FindingsWe modeled the potential distribution of the bullfrog in its native range based on different climate models and green-house gases emission scenarios, and projected the results onto South America for the years of 2050 and 2080. We also overlaid projected models onto the South American network of protected areas. Our results indicate a slight decrease in potential suitable area for bullfrog invasion, although protected areas will become more climatically suitable. Therefore, invasion of these sites is forecasted.Conclusion/SignificanceWe provide new evidence supporting the vulnerability of the Atlantic Forest Biodiversity Hotspot to bullfrog invasion and call attention to optimal future climatic conditions of the Andean-Patagonian forest, eastern Paraguay, and northwestern Bolivia, where invasive populations have not been found yet. We recommend several management and policy strategies to control bullfrog invasion and argue that these would be possible if based on appropriate articulation among government agencies, NGOs, research institutions and civil society.

Local cohesion and radical right support: The case of the Swiss People’s Party

Radical right parties have become effective electoral competitors in many parts of Western Europe yet failed to achieve success in others. Much recent scholarship seeks to understand variation in radical right support. Here, we argue that local social cohesion boosts these parties’ vote shares. We use Swiss census data at the municipal level to measure local cohesion, drawing on indicators of residents’ commuting patterns, linguistic similarities and home ownership. Regression analysis shows that social cohesion is a positive predictor of local level support for the Swiss People’s Party, but not for any other major party. Hierarchical logit models combining aggregate cohesion measures with survey data demonstrate this contextual effect on individuals’ vote choices.

Meeting the challenge of China: the Vietnamese garment industry in the post MFA era

AbstractAlthough China has diversified into sophisticated, higher value‐added exports, it is still a formidable competitor in global markets for basic labour‐intensive products. It is the world's largest exporting country of textiles and garments, the archetypical driver of industrial growth both in developed countries in the past and in most newly industrializing countries more recently. When the export restrictions under the Multi‐Fibre Arrangement (MFA) ended at the start of 2005, it was predicted that China would greatly increase its market shares at the expense of most competitors, except perhaps India. Vietnam has proved to be an effective competitor in the garment industry in markets where China is dominant. In this article, we investigate how key export‐oriented garment suppliers of Vietnam have been coping with competitive challenges in the post MFA era at a time when global buyers have been reorganizing their international production networks. We emphasize the influence of different global value chains on upgrading since Vietnamese suppliers switched to the US market after the implementation of the US Bilateral Trade Agreement in 2001. We note the uneven performance of Vietnamese garment suppliers, with some lagging behind others in upgrading and competitiveness, and their different responses to Vietnam's growing labour shortages. We base the article mainly on interviews conducted over the 2001–2008 period with garment companies and global buyers in Vietnam, Hong Kong and China.

Nitrogen uptake and preference in a forest understory following invasion by an exotic grass

Plant-soil interactions have been proposed as a causative mechanism explaining how invasive plant species impact ecosystem processes. We evaluate whether an invasive plant influences plant and soil-microbe acquisition of nitrogen to elucidate the mechanistic pathways by which invaders might alter N availability. Using a (15)N tracer, we quantify differences in nitrogen uptake and allocation in communities with and without Microstegium vimineum, a shade-tolerant, C(4) grass that is rapidly invading the understories of eastern US deciduous forests. We further investigate if plants or the microbial biomass exhibit preferences for certain nitrogen forms (glycine, nitrate, and ammonium) to gain insight into nitrogen partitioning in invaded communities. Understory native plants and M. vimineum took up similar amounts of added nitrogen but allocated it differently, with native plants allocating primarily to roots and M. vimineum allocating most nitrogen to shoots. Plant nitrogen uptake was higher in invaded communities due primarily to the increase in understory biomass when M. vimineum was present, but for the microbial biomass, nitrogen uptake did not vary with invasion status. This translated to a significant reduction (P < 0.001) in the ratio of microbial biomass to plant biomass nitrogen uptake, which suggests that, although the demand for nitrogen has intensified, microbes continue to be effective nitrogen competitors. The microbial biomass exhibited a strong preference for ammonium over glycine and nitrate, regardless of invasion status. By comparison, native plants showed no nitrogen preferences and M. vimineum preferred inorganic nitrogen species. We interpret our findings as evidence that invasion by M. vimineum leads to changes in the partitioning of nitrogen above and belowground in forest understories, and to decreases in the microbial biomass, but it does not affect the outcome of plant-microbe-nitrogen interactions, possibly due to functional shifts in the microbial community as a result of invasion.

A Two-step Binding Model of PCSK9 Interaction with the Low Density Lipoprotein Receptor

PCSK9 (proprotein convertase subtilisin-like/kexin type 9) is an emerging target for pharmaceutical intervention. This multidomain protein interacts with the LDL receptor (LDLR), promoting receptor degradation. Insofar as PCSK9 inhibition induces a decrease in plasma cholesterol levels, understanding the nature of the binding interaction between PCSK9 and the LDLR is of critical importance. In this study, the ability of PCSK9 to compete with apoE3 N-terminal domain-containing reconstituted HDL for receptor binding was examined. Whereas full-length PCSK9 was an effective competitor, the N-terminal domain (composed of the prodomain and catalytic domain) was not. Surprisingly, the C-terminal domain (CT domain) of PCSK9 was able to compete. Using a direct binding interaction assay, we show that the PCSK9 CT domain bound to the LDLR in a calcium-dependent manner and that co-incubation with the prodomain and catalytic domain had no effect on this binding. To further characterize this interaction, two LDLR fragments, the classical ligand-binding domain (LBD) and the EGF precursor homology domain, were expressed in stably transfected HEK 293 cells and isolated. Binding assays showed that the PCSK9 CT domain bound to the LBD at pH 5.4. Thus, CT domain interaction with the LBD of the LDLR at endosomal pH constitutes a second step in the PCSK9-mediated LDLR binding that leads to receptor degradation.

The inhibitory effect of natural microflora of food on growth of Listeria monocytogenes in enrichment broths

The aims of this study were to (i) compare the inhibitory effects of the natural microflora of different foods on the growth of Listeria monocytogenes during enrichment in selective and non-selective broths; (ii) to isolate and identify components of the microflora of the most inhibitory food; and (iii) to determine which of these components was most inhibitory to growth of L. monocytogenes in co-culture studies. Growth of an antibiotic-resistant marker strain of L. monocytogenes was examined during enrichment of a range of different foods in Tryptone Soya Broth (TSB), Half Fraser Broth (HFB) and Oxoid Novel Enrichment (ONE) Broth. Inhibition of L. monocytogenes was greatest in the presence of minced beef, salami and soft cheese and least with prepared fresh salad and chicken pâté. For any particular food the numbers of L. monocytogenes present after 24 h enrichment in different broths increased in the order: TSB, HFB and ONE Broth. Numbers of L. monocytogenes recovered after enrichment in TSB were inversely related to the initial aerobic plate count (APC) in the food but with only a moderate coefficient of determination (R 2) of 0.51 implying that microbial numbers and the composition of the microflora both influenced the degree of inhibition of L. monocytogenes. In HFB and ONE Broth the relationship between APC and final L. monocytogenes counts was weaker. The microflora of TSB after 24 h enrichment of minced beef consisted of lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and enterococci. In co-culture studies of L. monocytogenes with different components of the microflora in TSB, the lactic acid bacteria were the most inhibitory followed by the Enterobacteriaceae. The least inhibitory organisms were Pseudomonas sp., enterococci and B. thermosphacta. In HFB and ONE Broth the growth of Gram-negative organisms was inhibited but lactic acid bacteria still reached high numbers after 24 h. A more detailed study of the growth of low numbers of L. monocytogenes during enrichment of minced beef in TSB revealed that growth of L. monocytogenes ceased at a cell concentration of about 10 2 cfu/ml when lactic acid bacteria entered stationary phase. However in ONE Broth growth of lactic acid bacteria was slower than in TSB with a longer lag time allowing L. monocytogenes to achieve much higher numbers before lactic acid bacteria reached stationary phase. This work has identified the relative inhibitory effects of different components of a natural food microflora and shown that the ability of low numbers of L. monocytogenes to achieve high cell concentrations is highly dependent on the extent to which enrichment media are able to inhibit or delay growth of the more effective competitors.

Feasibility of Organic Weed Management in Sweet Corn and Snap Bean for Processing

There is significant interest from processors in producing organic sweet corn and snap bean. However, large-scale production is necessary for this to be a practical and economical venture for processors. This study focused on the feasibility of managing weeds in organic sweet corn and snap bean, utilizing methods that are practical in large hectarage. Tactics such as rotary hoe, interrow cultivation, and a stale seedbed were evaluated alone or in combination. Hand-weeded and herbicide-based treatments were included for each crop for comparison. Percentage weed control, weed biomass, and crop yield were quantified, and net profit was calculated for each treatment. Organic weed management was feasible in snap bean, with yields similar among several of the organic treatments and the herbicide treatment in all 3 yr of the study. Interrow cultivation was the most effective means of organic weed control in snap bean. Organic weed management was possible in snap bean because it is a short-season crop and an effective competitor with weeds in the crop row. Organic weed management was more difficult in sweet corn because of the longer crop season and poor competition with weeds in the crop row. In sweet corn, the organic treatment involving three interrow cultivations was the only one consistently similar in yield to the herbicide treatments. Higher net profits were attained for most of the organic treatments in both crops because of the organic premium. Market saturation and organic premium adjustments are factors for grower consideration in this potential industry, particularly for sweet corn production.

Modeling and predicting competitive sorption of organic compounds in soil

Binary systems consisting of 1,2-dichlorobenzene (12DCB) + competitor were investigated over a range of concentrations of competitor in three natural sorbents with distinct characteristics. Two models, the ideal adsorbed solution theory (IAST) and the potential theory (Polanyi-based multisolute model), widely used in the prediction of multisolute sorption equilibrium from single-solute data, were used to simulate competitive sorption in our systems. The goal was to determine which multisolute model best represented the experimentally obtained multisolute data in natural sorbents of varied properties. Results suggested that for the sorbents and sorbates studied, the IAST model provided much better results. On average, the IAST model provided lower errors (23%) than the potential model (45%). The effect of competitor structure on the degree of competition was also investigated to identify any relationships between competition and structure using molecular descriptors. The competitors chlorobenzene, naphthalene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene all showed very similar degrees of competition, while benzene, phenanthrene, and pyrene were the least effective competitors toward 12DCB across all sorbents. Different sorption sites or sorption mechanisms might be involved in the sorption of these molecules leading to a lack of competitive behavior. A significant relationship between competitor structure and the degree of competition was observed at environmentally relevant sorbed competitor concentrations for the soil containing the highest fraction of hard carbon (Forbes soil).

The perceptual organization of sine-wave speech under competitive conditions

Speech comprises dynamic and heterogeneous acoustic elements, yet it is heard as a single perceptual stream even when accompanied by other sounds. The relative contributions of grouping "primitives" and of speech-specific grouping factors to the perceptual coherence of speech are unclear, and the acoustical correlates of the latter remain unspecified. The parametric manipulations possible with simplified speech signals, such as sine-wave analogues, make them attractive stimuli to explore these issues. Given that the factors governing perceptual organization are generally revealed only where competition operates, the second-formant competitor (F2C) paradigm was used, in which the listener must resist competition to optimize recognition [Remez, R. E., et al. (1994). Psychol. Rev. 101, 129-156]. Three-formant (F1+F2+F3) sine-wave analogues were derived from natural sentences and presented dichotically (one ear=F1+F2C+F3; opposite ear=F2). Different versions of F2C were derived from F2 using separate manipulations of its amplitude and frequency contours. F2Cs with time-varying frequency contours were highly effective competitors, regardless of their amplitude characteristics. In contrast, F2Cs with constant frequency contours were completely ineffective. Competitor efficacy was not due to energetic masking of F3 by F2C. These findings indicate that modulation of the frequency, but not the amplitude, contour is critical for across-formant grouping.

Use of poly(amido)amine dendrimers in prevention of early non-enzymatic modifications of biomacromolecules

Hyperglycaemia triggers the formation of both ‘early’ and advanced glycation end products, which are considered the major factors responsible for the complications of diabetes. Poly(amido)amine (PAMAM) dendrimers are relatively new class of materials with unique molecular structure predisposing them for the use as anti-glycation agents. The ability of poly(amido)amine (PAMAM) dendrimers G2 (MW 3256, 120 μmol/l) and G4 (MW 14215, 30 μmol/l) to inhibit the modification of proteins by high glucose (30 mmol/l, 37 °C, 72 h) was investigated using radiometric and spectrofluorometric assays. We monitored (a) non-enzymatic modifications of primary amino groups in BSA and polyamine compounds, and (b) the impact of anti-glycation agents on BSA conformation. Both PAMAM dendrimers and poly( l-lysine) (MW 70 kDa) effectively reduced BSA glycation, while undergoing the time-dependent modification themselves. Such a modification was a function of a number of available free amino groups per molecule, however, both dendrimers and poly( l-lysine) were equally effective in glucose scavenging. PAMAMs neither affected BSA conformation nor formed stable complexes with a protein, while non-glycated poly( l-lysine) significantly quenched BSA fluorescence. Our results encourage raising the hypothesis that PAMAM dendrimers may be considered effective and safe chemical competitors for non-enzymatic modification by glucose, thus confirming the earlier in vivo study showing the inhibition of protein modification in experimental diabetes in the presence of PAMAM dendrimers.

Technology-Based Changes of International Division of Labor in Recent Decades (Analysis Based on Selected Economies)

One of the undeniable feature of the contemporary international division of labor is increasing importance of ITC technologies and social capital, which allow the economy to be more competitive due to arising many connections to the global information networks. Based on conducted research it seems that a straightforward distinction between most developed, post-industrial economies and other economies on different, but lower stages of development, is simply obsolete. First and foremost, some developing countries are gaining on importance in international trade of high-tech products and knowledge- intensive business services (China and India are the most evident examples). On the other hand, these countries have become more and more effective competitors to developed countries in so called creative industries. This is partly caused by foreign direct investments flowed in especially during two past decades, but also is a consequence of social and educational policy leading to development of networked human capital, a substantial asset in the modern global economy. In a way such progress of developing countries under scrutiny in this article should be considered as an indication for Eastern European countries, such Poland and Ukraine, which are technologically backward on course for knowledge-based economy creation.

The cleidocranial dysplasia‐related R131G mutation in the Runt‐related transcription factor RUNX2 disrupts binding to DNA but not CBF‐β

Cleidocranial dysplasia (CCD) is caused by haploinsufficiency in RUNX2 function. We have previously identified a series of RUNX2 mutations in Korean CCD patients, including a novel R131G missense mutation in the Runt-homology domain. Here, we examine the functional consequences of the RUNX2(R131G) mutation, which could potentially affect DNA binding, nuclear localization signal, and/or heterodimerization with core-binding factor-beta (CBF-beta). Immunofluorescence microscopy and western blot analysis with subcellular fractions show that RUNX2(R131G) is localized in the nucleus. Immunoprecipitation analysis reveals that heterodimerization with CBF-beta is retained. However, precipitation assays with biotinylated oligonucleotides and reporter gene assays with RUNX2 responsive promoters together reveal that DNA-binding activity and consequently the transactivation of potential of RUNX2(R131G) is abrogated. We conclude that loss of DNA binding, but not nuclear localization or CBF-beta heterodimerization, causes RUNX2 haploinsufficiency in patients with the RUNX2(R131G) mutation. Retention of specific functions including nuclear localization and binding to CBF-beta of the RUNX2(R131G) mutation may render the mutant protein an effective competitor that interferes with wild-type function.

Comparative Digestion of Food Among Wildlife in Texas: Implications for Competition

Success in competition for a limited food resource can be determined in part by how efficiently a species digests food. We conducted in vivo trials to compare digestive performance by a guild of mast-consuming species in southern Texas: wild boar (Sus scrofa), white-tailed deer (Odocoileus virginianus), collared peccary (Pecari tajacu), wild turkey (Meleagris gallopavo), raccoon (Procyon lotor), and southern plains woodrat (Neotoma micropus). Four individuals of each species were fed commercial pellets and chromium-marked fiber to determine rates of passage. Dry matter and intake of digestible energy, and digestibility of detergent fiber, crude protein, and gross energy (metabolizability for turkeys) were determined for each species. Mean retention and time of passage of 95% of marked fiber were calculated. Digestibility and time of retention by wild boars was similar to foregut-fermenting species and equal to or greater than smaller hindgut fermenters. White-tailed deer and collared peccaries showed similar capabilities of digestion and retention, and also had higher digestibilities of fiber than small hindgut fermenters. Turkeys and raccoons had fast rates of passage and showed little digestion of fiber. Southern plains woodrats had intermediate digestibilities and times of retention. Wild boars are expected to be effective competitors for mast because of their digestive efficiency, large body size, and potential for consumption of large quantities of food.

Ecophysiological differences between genetic lineages facilitate the invasion of non‐native Phragmites australis in North American Atlantic coast wetlands

Summary 1. Over the last century, native Phragmites australis lineages have been almost completely replaced along the North American Atlantic coast by an aggressive lineage originating from Eurasia. Understanding the mechanisms that facilitate biological invasions is critical to better understand what makes an invasive species successful. 2. Our objective was to determine what makes the introduced lineage so successful in the study area by specifically investigating if morphological and ecophysiological differences exist between native and introduced genetic lineages of P. australis. We hypothesized a priori that due to phenotypic differences and differences in plant nitrogen (N) content between lineages, the introduced lineage would have a greater photosynthetic potential. 3. In situ ecophysiological and morphological data were collected for 2 years in a mid‐Atlantic tidal marsh and in a glasshouse experiment. We measured photosynthetic parameters (Amax, water use efficiency, stomatal conductance) using infrared gas analysis, in conjunction with ecophysiological and morphological parameters [specific leaf area (SLA), leaf area, chlorophyll content, N content]. 4. Introduced P. australis maintained 51% greater rates of photosynthesis and up to 100% greater rates of stomatal conductance which are magnified by its 38–83% greater photosynthetic canopy compared to the native type. The introduced lineage also had a significantly greater SLA and N content. Glasshouse‐grown plants and naturally occurring populations demonstrated similar trends in ecophysiological characteristics, verifying the heritability of these differences. These ecophysiological differences, when combined with an extended growing season, provide the mechanism to explain the success of introduced P. australis in North America. 5. Our findings suggest the native type is a low‐nutrient specialist, with a more efficient photosynthetic mechanisms and lower N demand, whereas the introduced type requires nearly four times more N than the native type to be an effective competitor. 6. Synthesis. Our study is the first to combine field and laboratory data to explain a biological invasion attributed to ecophysiological differences between genetic lineages. Our data corroborates earlier work suggesting anthropogenic modification of wetland environments has provided the state change necessary for the success of introduced P. australis. Finally, our results suggest that genotypic differences within species merit further investigations, especially when related to biological invasions.

Changing role of BRIC countries in technology-driven international division of labor

In contemporary international division of labor the importance of ICT technologies and social capital is increasing, and allows the economy to be more competitive due to arising many connections to the global information networks. The major goal of this article was analyzing (mostly in descriptive manner) and comparing the recent trends in GDP growth and its composition and international trade of high-technology manufactures and services for developed and BRIC countries. The results of conducted statistical data analysis justify the conclusion that some developing economies, especially China and India, are in fact gaining on importance in international trade of high-tech products and knowledge-intensive business services, even having become more effective competitors to the post-industrial economies in so called creative industries. Such an outcome has been caused mostly by foreign direct investments flowed in during two last decades, but also was conditioned by social and educational policy leading to development of networked human capital.

Evidence for Reduction of Native Mosquitoes With Increased Expansion of Invasive &lt;I&gt;Ochlerotatus japonicus japonicus&lt;/I&gt; (Diptera: Culicidae) in the Northeastern United States

Ochlerotatus japonicus japonicus (Theobald) is an invasive mosquito native to Japan, Korea, and eastern China. The species was first detected in the northeastern United States in 1998 and has rapidly spread throughout much of eastern North America. In addition to used tire casings, Oc. j. japonicus develops in a wide variety of artificial and natural container habitats, especially rock pools along stream beds. In an effort to evaluate the invasion success and impact of Oc. j. japonicus on populations of native container dwelling species, waste tire disposal sites and natural rock pool habitats were sampled for mosquito larvae throughout Connecticut in 2005, and data were compared with results from prior surveys made in 1987 and 1999. Oc. j. japonicus was the predominant species collected at the waste tire disposal sites regardless of surrounding landscape features, accounting for 55.9% of all larvae. A comparison with collections from prior surveys revealed a 90% reduction in the relative abundance of larval populations of Oc. triseriatus (Say) and significant reductions among larval populations of Oc. atropalpus (Coquillett) and Culex restuans Theobald. Oc. j. japonicus was also the most abundant mosquito collected in rock pool habitats, accounting for nearly 80% of all collected larvae, except where water temperatures exceeded 30 degrees C. This was concomitant with significant declines in the relative abundance of Oc. atropalpus and Cx. restuans. We conclude that Oc. j. japonicus is a potentially effective competitor in rock pool and tire environments and may be responsible for reducing populations of several native species occupying these habitats through interspecific competition for limited resources. The exclusion of Oc. j. japonicus from warm water pools further suggests that a temperature barrier may exist for Oc. j. japonicus and that populations may not be able to colonize southern regions of the United States with relatively high summer temperatures.

DogsCanis familiarisas carnivores: their role and function in intraguild competition

Dogs Canis familiaris are the world's most common carnivore and are known to interact with wildlife as predators, prey, competitors, and disease reservoirs or vectors. 2. Despite these varied roles in the community, the interaction of dogs with sympatric wild carnivore species is poorly understood. We review how dogs have been classified in the literature, and illustrate how the location and ranging behaviour of dogs are important factors in predicting their interactions with wild prey and carnivores. 3. We detail evidence of dogs as intraguild competitors with sympatric carnivores in the context of exploitative, interference and apparent competition. 4. Dogs can have localized impacts on prey populations, but in general they are not exploit- ative competitors with carnivores. Rather, most dog populations are highly dependent on human-derived food and gain a relatively small proportion of their diet from wild prey. However, because of human-derived food subsidies, dogs can occur at high population densities and thus could potentially outcompete native carnivores, especially when prey is limited. 5. Dogs can be effective interference competitors, especially with medium-sized and small carnivores. Dogs may fill the role of an interactive medium-sized canid within the carnivore community, especially in areas where the native large carnivore community is depauperate. 6. Dogs can also be reservoirs of pathogens, because most populations around the world are free-ranging and unvaccinated. Diseases such as rabies and canine distemper have resulted in severe population declines in several endangered carnivores coexisting with high-density dog populations. Dogs can therefore be viewed as pathogen-mediated apparent competitors, capable of facilitating large-scale population declines in carnivores. 7. Based on this information, we propose conceptual models that use dog population size and ranging patterns to predict the potential for dogs to be intraguild competitors. We discuss how interactions between dogs and carnivores might influence native carnivore communities.

TAF4/4b·TAF12 Displays a Unique Mode of DNA Binding and Is Required for Core Promoter Function of a Subset of Genes

The major core promoter-binding factor in polymerase II transcription machinery is TFIID, a complex consisting of TBP, the TATA box-binding protein, and 13 to 14 TBP-associated factors (TAFs). Previously we found that the histone H2A-like TAF paralogs TAF4 and TAF4b possess DNA-binding activity. Whether TAF4/TAF4b DNA binding directs TFIID to a specific core promoter element or facilitates TFIID binding to established core promoter elements is not known. Here we analyzed the mode of TAF4b.TAF12 DNA binding and show that this complex binds DNA with high affinity. The DNA length required for optimal binding is approximately 70 bp. Although the complex displays a weak sequence preference, the nucleotide composition is less important than the length of the DNA for high affinity binding. Comparative expression profiling of wild-type and a DNA-binding mutant of TAF4 revealed common core promoter features in the down-regulated genes that include a TATA-box and an Initiator. Further examination of the PEL98 gene from this group showed diminished Initiator activity and TFIID occupancy in TAF4 DNA-binding mutant cells. These findings suggest that DNA binding by TAF4/4b-TAF12 facilitates the association of TFIID with the core promoter of a subset of genes.