A new plot for the kinetic analysis of dead-end enzyme inhibitors

A new procedure to characterize reversible dead-end inhibitors is presented. Preliminary identification of the inhibitor type is made by plotting vo/vi against the inhibitor concentration at different substrate concentrations. The inhibition constants for competitive, uncompetitive and mixed dead-end inhibitors are determined by secondary plots of l/(slope) vs [S], l/(slope) vs l/[S] and (slope)(Ks + [S] vs [S] respectively. These secondary plots render straight lines only for their corresponding type of inhibitor. For noncompetitive inhibitors all the secondary plots used yield straight lines. Therefore, the application of this plotting procedure leads to unambiguous diagnosis of the inhibitor type. An important feature of the procedure presented here is that the variable used (vo/vi) is independent on Vmax values. Therefore, experimental values obtained from enzyme preparations showing significant differences in their specific activities -i.e. enzyme coming from different purification steps- can be used.     

A chemical approach to the fine structure of biomolecular complexes: the amino terminal region of the 50S ribosomal "A" protein from Bacillus stearothermophilus.

An experimental approach and methodology are described for determining the reactive properties and ionization constants of individual functional groups of proteins within biomolecular complexes. The ionization constants and reactivities of the methionyl-l amino terminus and the lysyl-3 residue of the alanine rich 50S ribosomal "A" protein from Bacillus stearothermophilus have been determined by an extension of the competitive labeling technique used by H. Kaplan, K. J. Stevenson, and B. S. Hartley ((1971), Biochem. J. 124, 289-299). This approach employs (1-14C)- and (3H)acetic anhydride in a double-labeling procedure. In 0.1 M KCl-0.02 M Mg2+-0.05 M Veronal at 10 degrees the methionyl-l amino terminus has a pKa of 7.5 and is exposed on the surface of the ribosome. The lysyl-3 has a pKa of 10 and is also exposed to solvent at the surface of the 50S subunit. Based on a linear free energy relationship (Bronsted plot) obtained with a series of standard amines the methionyl amino terminus has a substantially higher reactivity than expected from its ionization constant. The lysyl epsilon-amino group has the expected reactivity. The abnormally high reactivity of the methionyl amino terminus can only be accounted for by a specific interaction with other functional groups in the ribosome. These data support the proposal that the charged state of this residue is important in the structure and function of the "A" protein at the surface of the ribosome.     

A new plot for multiple enzyme inhibition

A new graphical method is described for analyzing the results of multiple inhibition experiments. It is applicable to either single- or multi-substrate enzyme systems obeying Michaelis-Menten kinetics and is valid irrespective of the type of inhibition (competitive, noncompetitive, uncompetitive, mixed). According to this method, mutually exclusive inhibitor binding gives rise to lines that converge on the vertical axis, whereas mutually nonexclusive inhibitors yield lines that intersect to the left of the vertical axis. It has been pointed out that the inhibitor interaction factor can be determined directly from multiple inhibition experiments only if at least one of the inhibitors is noncompetitive. When this is the case, the present plot provides a very simple way of determining the inhibitor interaction factor from the coordinates of the intersection point.     

Effects of sequential pollination on the success of "fast" and "slow" pollen donors in Hibiscus moscheutos (Malvaceae)

Competition among pollen grains for the chance to fertilize ovules typically involves two stages: arrival times on stigmas and/or the growth of pollen tubes through styles. In a previous study of Hibiscus moscheutos, we found that individual pollen donors often differed in pollen tube competitive ability. Here we determined whether short delays in pollen arrival time altered the average success of "fast" and "slow" pollen donors when both types of pollen experienced the same delays. Hand-pollination experiments were carried out using four pairs of pollen donors that differed in competitive ability. We allowed delays of 15 or 30 min between the first and second pollen donor and then determined seed paternity using allozyme markers. The second donor typically sired fewer seeds than pollen that arrived earlier, but, contrary to expectation, "faster" pollen did not always sire significantly more seeds than "slower" pollen when each was applied after delays of the same duration. In two of the four pairs of donors, differences that were seen following simultaneous pollinations disappeared when each type of pollen was applied following identical delays of 15 or 30 min. This unexpected response suggests that the dynamics of pollen tube competition are more complex than anticipated.     

"Malignant" contracture of the eye socket

A new method for reconstruction of "malignant" contracture of the eye socket is described using a simple procedure based on the principle of epithelial inlay. The lining consists of a free skin graft. No cumbersome external appliances for the prevention of contraction of the graft are used; hence the hospitalization is minimized. The results have been satisfactory.     

Demonstration of endogenous "imipramine like" material in rat brain

The extraction and partial purification of an endogenous "imipramine- like" material from rat brain is described. The endogenous factor obtained after gel filtration and silica chromatography inhibits [3H] imipramine specific binding and mimics the inhibitory effect of imipramine on [3H] serotonin uptake in both brain and platelet preparations. The effects of the endogenous material are dose-dependent and it inhibits [3H] imipramine binding in a competitive fashion. The factor is unevenly distributed in the brain with high concentration in the hypothalamus and low concentration in the cerebellum.     

Differential recognition of "enkephalinase" and angiotensin-converting enzyme by new carboxyalkyl inhibitors

New carboxylalkyl compounds derived from Phe-Leu and corresponding to the general formula C6H5-CH2-CH(R)CO-L.Leu with R = -COOH, 3, R = -CH2-COOH, 4, R = -NH-CH2-COOH, 5, R = -NH-(CH2)2-COOH, 6, have been found to inhibit the breakdown of the Gly3-Phe4 bond of [3H] Leu-enkephalin or [3H]D.Ala2-Leu-enkephalin resulting from the action of the mouse striatal metallopeptidases: "enkephalinase" or angiotensin-converting enzyme (A.C.E.). The carboxyl coordinating ability of the Zn atom seems to be significantly higher in ACE than in "enkephalinase". Moreover, IC50 values against "enkephalinase" were found in the same range whatever the length of the chain bearing the carboxyl group whereas a well-defined position of this group with respect to the Zn atom is required for strong ACE inhibition. These features suggest a larger degree of freedom of the carboxyalkyl moieties within the active site of "enkephalinase". Therefore the differential recognition of active sites of both peptidases leads to: i) N-(carboxymethyl)-L-Phe-L-Leu, 5, a competitive inhibitor of "enkephalinase" (KI = 0.7 microM) and ACE (KI = 1.2 microM) which could be used as mixed inhibitor for both enzymes; ii) N-[(R,S)-2-carboxy, 3-benzylpropanoyl]-L-Leucine, 3, a full competitive inhibitor of "enkephalinase" (KI = 0.34 microM) which does not interact with ACE (IC50 greater than 10,000 microM). This compound can be considered as the first example of a new series of highly potent and specific "enkephalinase" inhibitors.     

Keratins and protein synthesis: the plot thickens

In addition to protecting epithelial cells from mechanical stress, keratins regulate cytoarchitecture, cell growth, proliferation, apoptosis, and organelle transport. In this issue, Vijayaraj et al. (2009. J. Cell Biol. doi:10.1083/jcb.200906094) expand our understanding of how keratin proteins participate in the regulation of protein synthesis through their analysis of mice lacking the entire type II keratin gene cluster.Keratins are members of the intermediate filament family. They form intricate cytoskeletal networks via the assembly and organization of 10–12-nm filaments, whose formation is initiated through coiled-coil interactions between a type I keratin (e.g., K18 and -19) and a type II keratin (e.g., K8; Kim and Coulombe, 2007). Most keratin proteins have been shown to contribute to the protection of cells and tissues from mechanical and nonmechanical stresses (Toivola et al., 2005; Kim and Coulombe, 2007). Whereas the large number of keratin genes (n = 54; Schweizer et al., 2006) and the heteropolymerization-based assembly of their protein products should in part serve the purpose of modulating the viscoelastic properties of keratin networks to assist various cellular needs, common sense dictates that there should be additional roles for these proteins. Not surprisingly, efforts over the last decade have implicated keratin proteins in several nontraditional functions, including cytoarchitecture, proliferation and growth, apoptosis, and organelle transport, to name a few (Toivola et al., 2005; Kim and Coulombe, 2007). Yet, the high homology between several keratin proteins along with their overlapping distribution in epithelia has limited researchers'' progress toward uncovering the full range of keratin function in vivo (Baribault et al., 1994; Tamai et al., 2000; McGowan et al., 2002; Kerns et al., 2007). In this issue, Vijayaraj et al. report on the ultimate bypass of redundancy by eliminating all keratin filaments via the generation of a mouse strain lacking all type II keratins (KtyII^−/− mice). The study of these mice, which are viable until embryonic day 9.5, led to the discovery of a novel mechanism through which keratin proteins regulate protein synthesis and cell growth (Kim et al., 2006, 2007; Galarneau et al., 2007). The authors'' findings also showcase the recent conceptual and technical advances of chromosome engineering in the mouse genome.For over a decade, the Cre-loxP site-specific recombination system has been a popular method to generate targeted conditional knockout embryonic stem (ES) cells and mice. Although recombination efficiency is inversely proportional to the distance between loxP sites, larger chromosomal rearrangements have been successfully engineered into mouse ES cells using Cre-loxP (Ramírez-Solis et al., 1995). Generating such targeting vectors is cumbersome using traditional cloning methods. This said, DNA recombineering eliminates many of the constraints of finding unique restriction enzyme sites in genomic DNA sequences (Liu et al., 2003). Also, an Sv129 bacterial artificial chromosome (BAC) library generated from AB2.2 ES cells makes it easier to obtain large genomic sequences or even target ES cells directly with loxP-containing BACs (Liu et al., 2003; Adams et al., 2005). Finally, the Mutagenic Insertion and Chromosome Engineering Resource (MICER), a library of ready-made targeting vectors spread throughout the mouse genome, is now available (Adams et al., 2004). Vijayaraj et al. (2009) used MICER vectors to remove the entire 0.68-Mb keratin type II cluster on mouse chromosome 15 (Fig. 1 A). Owing to the interdependency of type I and II keratins for 10-nm filament assembly (Fig. 1 B), the resulting KtyII^−/− mice represent the first successful elimination of all keratin filaments from an organism as complex as a mouse.Open in a separate windowFigure 1.Genome organization, assembly, and epithelial function of keratins. (A) Arrangement of keratin clusters in the mouse genome. Human keratin genes that have not been identified or annotated in the mouse genome are shown on the bottom side and marked with a question mark. The arrows mark the boundaries of the region deleted by Vijayaraj et al. (2009) on mouse chromosome 15. (B) Summary of the multistep pathway through which type I and II keratin protein monomers polymerize to form 10-nm filaments. The antiparallel docking of the lollipop-shaped coiled-coiled dimers along their lateral surfaces generates structurally apolar tetramers and accounts for the lack of polarity of assembled keratin intermediate filaments. For all steps in the pathway, the forward (assembly promoting) reaction is heavily favored in vitro (Kim and Coulombe, 2007). (C) Keratins influence the localization and function of many cellular components. As highlighted here, keratins interact with and modulate the mTOR pathway in several ways, both in skin keratinocytes and gut epithelial cells, and regulate the localization of microtubules, γ-tubulin, and GLUT transporters in polarized epithelia. Components are not drawn to scale in this schematic.KtyII^−/− embryos display severe growth retardation and die midgestation (Baribault et al., 1993; Hesse et al., 2000; Tamai et al., 2000). Smaller cell size has been observed previously in K17^−/− skin keratinocytes and K8^−/− liver hepatocytes, correlating with altered Akt/mammalian target of rapamycin (mTOR) signaling (Fig. 1 C) and a reduction in bulk protein synthesis (Kim et al., 2006; Galarneau et al., 2007). Although K17 appears to modulate the mTOR pathway through its physical interaction with 14-3-3–σ in keratinocytes (Fig. 1 C; Kim et al., 2006), the mechanism for how K8 influences protein synthesis in hepatocytes is less clear but appears to integrate responses to both insulin and integrin stimulation (Galarneau et al., 2007). Loss of K8 is also associated with an increase in Akt activity (Galarneau et al., 2007), which is contrary to the findings in the K17^−/− setting (Kim et al., 2006), calling into question whether the two settings use the same mechanism to modulate mTOR signaling. Vijayaraj et al. (2009) uncover yet another path through which keratins are able to influence protein synthesis. The authors find that loss of all keratin filaments causes mislocalization of GLUT transporters and disruption of glucose homeostasis through AMP kinase (AMPK) activation. In addition, the authors report that in the absence of the keratin network, AMPK phosphorylates Raptor, which then interacts with mTOR to repress protein synthesis and hamper cell growth (Fig. 1 C). These findings further the evidence for an important role of keratin proteins (or filaments) in the regulation of translation and epithelial cell growth. However, they also raise the question of whether keratins affect mTOR signaling via an as of yet unknown, common denominator or whether several mechanisms come together, perhaps in a cell type– and context-dependent fashion, to achieve the same downstream effect.Unlike actin and microtubules, keratin filaments are not believed to possess intrinsic polarity (Fig. 1 B). However, K8/K18 and/or K8/K19 filaments play a significant role in maintaining apicobasal compartmentalization in simple epithelial linings in both the small intestine (Ameen et al., 2001; Oriolo et al., 2007) and colon of adult mice (Toivola et al., 2004) and have also been implicated in organelle transport (Toivola et al., 2005; Kim and Coulombe, 2007). The mechanism or mechanisms accounting for this surprising influence of keratins on the establishment and maintenance of spatial order in epithelial cells are unknown. Ameen et al. (2001) and Oriolo et al. (2007) recently made a dent in this mystery by showing that K8/K18 filaments are necessary for the proper localization of γ-tubulin to the apical compartment in polarized epithelial cells, thereby participating in the organization of noncentrosomic microtubules (note: the interested reader should examine a recent study by Bocquet et al. [2009], which shows a role for neuronal intermediate filaments in tubulin polymerization in axons). Similar to previous observations made in K8^−/− mice (Ameen et al., 2001; Toivola et al., 2004), Vijayaraj et al. (2009) show that apical proteins, particularly GLUT1 and -3, are mislocalized in KtyII^−/− embryonic epithelia. However, in this instance, microtubule organization appears to be intact. Although the authors'' experimental findings again nicely demonstrate a role for keratin proteins in the establishment of polarity in simple epithelial settings, the underlying mechanism or mechanisms still need to be ascertained.The mouse model generated by Vijayaraj et al. (2009) has important implications for the field of keratin biology and intermediate filaments in general. It will allow researchers to address central questions about the contributions of keratins during development and tissue homeostasis unencumbered by the redundancy of properties and functions among members of this large family. The availability of tissue- or cell type–specific promoters makes it possible to express the Cre recombinase in specific epithelial settings, thereby promoting the elimination of keratins in a more restricted fashion. It will be interesting to see how the total loss of keratin filaments affects different tissues and subpopulations of cells, highlighting essential functions and perhaps uncovering previously unappreciated roles for keratins in complex cellular processes.     

Progesterone measurement using "stripped" corticosteroid binding globulin (CBG)

Modifications in an existing competitive protein binding assay for progesterone have been made which provide a readily available and rich source of binding sites on the corticosteroid binding globulin (CBG). The primary and most important modification is the rapid removal of endogenous steroids from plasma by gel filtration at an elevated temperature. The ‘stripped’ protein retains full CBG activity, but is cleared of 95% of its endogenous steroids. This stripping procedure provides not only increased number of binding sites, but in conjunction with the other modifications also eliminates some of the variability in the assay.     

Potent inhibition of angiotensin-converting enzyme by [des-Pro3]-bradykinin or "converstatin" in comparison with Captopril

The mechanism of bradykinin-potentiating activity of [des-Proline3]-bradykinin, a kinin originally generated from human plasma protein by trypsin, was studied in terms of its inhibitory actions on angiotensin-converting enzyme and kininase II prepared from rat lung. The results were compared with those obtained with Captopril. [Des-Pro3]-bradykinin was found to have a potent inhibitory action against angiotensin-converting enzyme with a K1 of 4.5 X 10(-12) M, which is approximately 7 times more potent than Captopril. It was also inhibitory to kininase II with a Ki of 4 X 10(-11) M, which is approximately 2,300-fold more potent than Captopril. The pattern of inhibition was purely competitive with increased apparent Km but no change in apparent Vmax for both angiotensin-converting enzyme and kininase II. This is in contrast to Captopril, which showed a mixed competitive and non-competitive type of inhibition with increased apparent Km and decreased Vmax for both enzymes. Such a potent inhibitory activity of [des-Pro3]-bradykinin or Arg-Pro-Gly-Phe-Ser-Pro-Phe-Arg is noteworthy, and accordingly we propose the name "converstatin" for this peptide.     

"De-epithelization" and dermal pedicles.

Biopsy specimens from 38 "de-epithelized" dermal pedicles were examined microscopically. There was considerable variation in the depth of the plane among surgeons, procedures, and even between specimens from two sides of a bilateral procedure done by the same surgeon. Usually, the "de-epithelization" removed all the epidermis plus the upper layer of dermis containing the pilosebaceous apparatus. The significance of this finding as related to the future development of epidermal inclusion cysts is uncertain. Also, it brings into question the importance of "the dermal plexus circulation," which many have thought to be critical for viability of the nipple.     

plot2groups: an R package to plot scatter points for two groups of values

Background

Researchers usually employ bar graphs to show two groups of data, which can be easily manipulated to yield false impressions. To some extent, scatterplot can retain the real data values and the spread of the data. However, for groups of numeric data, scatterplot may cause over-plotting problems. As a result, many values all stack on top of each other.

Results

We recently implemented an R package, plot2groups, to plot scatter points for two groups values, jittering the adjacent points side by side to avoid overlapping in the plot. The functions simultaneously calculate a P value of two group t- or rank-test and incorporated the P value into the plot.

Conclusions

plot2groups is a simple and flexible software package which can be used to visualize two groups of values within the statistical programming environment R.

     

A self-administered odor identification test procedure using the "Sniffin' Sticks"

Assessment of smell function in clinical routine is often limited due to a lack of time and/or costs of the personnel administering the test. The aim of the present study was to validate a procedure allowing for self-administered olfactory testing in a clinical setting. Seventy-four healthy subjects (13 male, 61 female) from 18 to 30 years of age (mean 20.3 years) were tested on 2 days (interval 7-21 days, mean 8.7 days) with 16 odors of the "Sniffin' Sticks" identification test kit. On one occasion, the test was administered by an examiner. On another occasion, subjects administered the test to themselves, with the odors being identified after they had been "painted" on a sheet of paper. No significant differences were obtained between the results from both test procedures. With a maximum score of 16, assisted testing yielded a mean score of 13.7 [standard deviation (SD) 1.3] while the self-administered procedure yielded an average score of 13.8 (SD = 1.5) (P = 0.72). The mean difference between the assisted and the self-administered smell test procedures was 0.05 (SD = 1.28). The 95% confidence interval of differences ranged from -2.51 to 2.61. These results suggest that odor identification with the Sniffin' Sticks can also be administered by the subjects themselves.     

Reconstruction of the medial half of the lower eyelid using a "switch" split-lid procedure

Reconstruction of the medial half of the lower eyelid has one major disadvantage: It produces a scar at right angles to the eyelid rim. In contrast, use of a "switch" split-lid procedure avoids this inconvenience. The lateral half of the lower eyelid is split in two lamellae. The inner layer is transferred medially, and the resulting defect is closed with a buccal graft. The outer layer is drawn laterally to cover the raw surface of the mucosal pedicle and graft. The surplus of skin over the lateral canthal area is removed. This procedure, which so far has been used in three patients, promises to be a useful alternative for reconstruction of the medial half, but not more, of the lower eyelid.     

A "hanging" coverslip method for cell surface iodination of monolayer cultures

A procedure is described by which the use of a 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenyl glycoluril (iodogen)-coated coverslip to iodinate the cell surface proteins of monolayer cultures has been improved by "hanging" the coverslip at a defined distance from the cells. This method allows gentle manipulation of the cell culture, resulting in retention of high cell viability and in recovery of the cell monolayer with a minimum of mechanical damage. In addition, it allows the safe disposal of the radioactive coverslip upon completion of the reaction. Finally, the labeling is surface specific. The application of this procedure to 3T3 fibroblasts results in labeling of proteins comparable to lactoperoxidase-catalyzed iodinations.     

Purification and characterization of different "acid" beta-galactosidases from sheep kidney.

1. Two "acid" forms, Am and Al, of beta-galactosidase from sheep kidney have been isolated and purified 349- and 154-fold, respectively, with a recovery of about 8%. 2. Their mol. wts were about 450,000 and 230,000, respectively. Am seems to be a dimer of Al. The aggregation is stimulated by NaCl. 3. The "acid" beta-galactosidase has a pH optimum between 4.0 and 5.0 for both forms. They are located in the lysosomes. The optimal temperature is 37 degrees C and 40 degrees C for Al and Am forms, respectively. 4. Three peaks were detected by isoelectric focusing. After sialidase treatment, these peaks were obtained at higher pH values. 5. The activation energy values were 10.75 and 11.72 kcal/mol for Am and Al, respectively. 6. A variety of chemicals were tested as possible activators or inhibitors. The enzyme is strongly inhibited by gamma-D-galactonolactone, and the kinetic evidence suggests a competitive inhibition in all cases.     

Market Failure and the Environmental Policies of Firms: Economic Rationales for "Beyond Compliance" Behavior

This paper is an inquiry into the circumstances under which the voluntary provision of environmental public goods might be sensible from a firm's point of view. If environmental externalities were the only departure from the economic assumptions of perfect competition, and if no firms had preferential access to superior (low-cost) stocks of natural resources, firms that volunteered to internalize costs could not survive. But because externalities coexist with other departures from the competitive paradigm, such as asymmetric information and oligopoly competition, firms may find it in their shareholders' interests to provide environmental public goods to a greater degree than required by law. A number of firms, especially in Europe and North America, assert that they are pursuing "beyond-compliance" environmental policies. From the perspective of a firm's shareholders, it makes sense to pursue such policies if they increase the firm's expected value or if they appropriately manage business risk.
This paper discusses economically rational explanations for such policies. It analyzes the ways in which a firm's chances of financial success in pursuing any one of them are influenced by the firm's market position and organizational capabilities and by the basic structure of the industry in which it competes.     

A Q-Q plot aids interpretation of the false discovery rate

False discovery rates are routinely controlled by application of the Benjamini–Hochberg step-up procedure to a set of p-values. A method is demonstrated for representing the values so obtained (the BH-FDRs) on a quantile–quantile (Q-Q) plot of the p-values transformed to the negative-logarithmic scale. Recognition of this connection between the BH-FDR and the Q-Q plot facilitates both understanding of the meaning of the BH-FDR and interpretation of the BH-FDR in a particular data set.     

Kinetic studies on bacterial plasma membrane ATPase (F1). Nucleotide-induced long term inactivation of ATP hydrolyzing activity is linked to the formation of multiple "tight" enzyme nucleotide complexes.

ADP and the ATP analogs Nb-S6ITP (6-[(3-carboxy-4-nitrophenyl)thio]-9-beta-D-ribofuranosylpurine 5'-triphosphate) and AMP-P(NH)P (adenyl-5'-yl imidodiphosphate) interact with soluble plasma membrane ATPase (F1) from Micrococcus species in two ways: (i) at short incubation times, these inhibitors exhibit the kinetics of competitive inhibition, (ii) at long incubation times, these inhibitors induce an inactivation of the ATPase which can be reversed only in the case of AMP-P(NH)P. Kinetic treatment of the long term inactivation by ADP or Nb-S6ITP reveals a pseudo-first order process via the formation of an enzyme-inhibitor complex for which a Km analogous constant is obtained that is identical with the corresponding Ki value of the competitive inhibition. The long term inactivation by ADP and Nb-S6ITP involves the successive "tight" binding of 6 +/- 1 nucleotides/F1 molecule. One additional ADP molecule/F1 complex which is also "tightly" bound has no effect on the ATPase activity. The long term inactivation by ADP and Nb-S6ITP is inhibited at higher inhibitor concentrations according to a kinetics analogous to a substrate excess inhibition. Evidence is presented indicating that the mechanism of ATP hydrolysis by F1 and the long term inactivation by ADP or Nb-S6ITP are related processes. The mechanism of long term inactivation by AMP-P(NH)P appears to be different from that of ADP or Nb-S6ITP.     

Different traits predict competitive effect versus response by <Emphasis Type="Italic">Bromus madritensis</Emphasis> in its native and invaded ranges

Community assembly and coexistence theories predict that both fitness and plant functional traits should influence competitive interactions between native and invasive species. The evolution of the increased competitive ability hypothesis predicts that species will grow larger (a measure of fitness) in their invaded than native range; hence we hypothesized that species might exert greater competitive effects in their invaded range, lessening the importance of functional traits for competitive outcomes. In a greenhouse experiment we compared traits and competitive interactions between Bromus madritensis (an annual grass) and resident species from its native range in Spain, and its invaded range in Southern California. As predicted, B. madritensis collected in California grew larger and had a greater competitive effect on resident species than B. madritensis collected in Spain. However, residents from California also suppressed the growth of B. madritensis more than species from its native range in Spain. Competitive interaction strengths were predicted by different suites of traits in the native versus invaded range of B. madritensis; surprisingly, however, size of the resident species (fitness), did not predict variation in competitive interactions. This study shows that different suites of traits may aid in identifying those native species likely to strongly compete with invaders, versus those that will be competitively suppressed by invaders, with important implications for the design of restoration efforts aimed at promoting native species growth and preventing invasion. More generally, our study shows that fitness differences may not be as important as traits when predicting competitive outcomes in this system.