Growth stimulatory angiotensin II type-1 receptor is upregulated in breast hyperplasia and in situ carcinoma but not in invasive carcinoma

Two different receptors which bind angiotensin II specifically have been identified in humans and were designated angiotensin II type-1 receptor (AT1) and angiotensin II type-2 receptor (AT2). They only have 34% sequence homology and act through different signalling pathways. AT1 stimulation has been implicated in hypertrophy and hyperplasia in various tissues. In order to study the involvement of AT1 in tissues from controls (n=10) and patients with hyperplasia (n=33), ductal carcinoma in situ (DCIS) (n=23) and invasive carcinoma of the breast (n=25), we tested biopsies and breast-derived cell lines using immunocytochemistry, in situ hybridisation and cell proliferation techniques. The results show specific overexpression of AT1 receptor on the cytoplasmic membrane of cells of hyperplastic lesions with and without atypia and on DCIS of the breast. Evidence for growth stimulation is provided by in vitro experiments showing growth induction by angiotensin II of T47D cells which express the AT1 but not the AT2 receptor. The expression of AT1 on the cell membrane disappears in invasive breast cancer cells suggesting a regulatory pathway which is no longer needed in invasive carcinoma. The specific AT1 expression upregulation might well be an important step in the pathogenesis of hyperplasia of the breast, which is regarded as a precursor lesion for breast cancer.     

Visualization of actin polymerization in invasive structures of macrophages and carcinoma cells using photoconvertible β-actin-Dendra2 fusion proteins

Actin polymerization controls a range of cellular processes, from intracellular trafficking to cell motility and invasion. Generation and elongation of free barbed ends defines the regions of actively polymerizing actin in cells and, consequently, is of importance in the understanding of the mechanisms through which actin dynamics are regulated. Herein we present a method that does not involve cell permeabilization and provides direct visualization of growing barbed ends using photoswitchable β-actin-Dendra2 constructs expressed in murine macrophage and rat mammary adenocarcinoma cell lines. The method exploits the ability of photoconverted (red) G-actin species to become incorporated into pre-existing (green) actin filaments, visualized in two distinct wavelengths using TIRF microscopy. In growing actin filaments, photoconverted (red) monomers are added to the barbed end while only green monomers are recycled from the pointed end. We demonstrate that incorporation of actin into intact podosomes of macrophages occurs constitutively and is amenable to inhibition by cytochalasin D indicating barbed end incorporation. Additionally, actin polymerization does not occur in quiescent invadopodial precursors of carcinoma cells suggesting that the filaments are capped and following epidermal growth factor stimulation actin incorporation occurs in a single but extended peak. Finally, we show that Dendra2 fused to either the N- or the C-terminus of β-actin profoundly affects its localization and incorporation in distinct F-actin structures in carcinoma cells, thus influencing the ability of monomers to be photoconverted. These data support the use of photoswitchable actin-Dendra2 constructs as powerful tools in the visualization of free barbed ends in living cells.     

Inhibiting TGF-β signaling in hepatocellular carcinoma

One of the main complications in patients with liver fibrosis is the development of hepatocellular carcinoma (HCC). An understanding of the molecular mechanisms leading to HCC is important in order to be able to design new pharmacological agents serving either to prevent or mitigate the outcome of this malignancy. The transforming growth factor-beta (TGF-β) cytokine and its isoforms initiate a signaling cascade which is closely linked to liver fibrosis, cirrhosis and subsequent progression to HCC. Because of its role in these stages of disease progression, TGF-β appears to play a unique role in the molecular pathogenesis of HCC. Thus, it is a promising target for pharmacological treatment strategies. Recent studies have shown that inhibition of TGF-β signaling results in multiple synergistic down-stream effects which will likely improve the clinical outcome in HCC. We also review a number of TGF-β inhibitors, most of which are still in a preclinical stage of development, but may soon be available for trial in HCC patients. Hence, it is anticipated that there will soon be new agents available for clinical investigations to evaluate the role of the TGF-β-associated signaling in this deadly cancer.     

Rapid nutrient cycling in leaf litter from invasive plants in Hawai’i

Physiological traits that contribute to the establishment and spread of invasive plant species could also have impacts on ecosystem processes. The traits prevalent in many invasive plants, such as high specific leaf areas, rapid growth rates, and elevated leaf nutrient concentrations, improve litter quality and should increase rates of decomposition and nutrient cycling. To test for these ecosystem impacts, we measured initial leaf litter properties, decomposition rates, and nutrient dynamics in 11 understory plants from the Hawaiian islands in control and nitrogen + phosphorus fertilized plots. These included five common native species, four of which were ferns, and six aggressive invasive species, including five angiosperms and one fern. We found a 50-fold variation in leaf litter decay rates, with natives decaying at rates of 0.2–2.3 year^–1 and invaders at 1.4–9.3 year^–1. This difference was driven by very low decomposition rates in native fern litter. Fertilization significantly increased the decay rates of leaf litter from two native and two invasive species. Most invasive litter types lost nitrogen and phosphorus more rapidly and in larger quantities than comparable native litter types. All litter types except three native ferns lost nitrogen after 100 days of decomposition, and all litter types except the most recalcitrant native ferns lost >50% of initial phosphorus by the end of the experiment (204–735 days). If invasive understory plants displace native species, nutrient cycling rates could increase dramatically due to rapid decomposition and nutrient release from invasive litter. Such changes are likely to cause a positive feedback to invasion in Hawaii because many invasive plants thrive on nutrient-rich soils.     

Contrasting effects of invasive plants in plant–pollinator networks

The structural organization of mutualism networks, typified by interspecific positive interactions, is important to maintain community diversity. However, there is little information available about the effect of introduced species on the structure of such networks. We compared uninvaded and invaded ecological communities, to examine how two species of invasive plants with large and showy flowers (Carpobrotus affine acinaciformis and Opuntia stricta) affect the structure of Mediterranean plant–pollinator networks. To attribute differences in pollination to the direct presence of the invasive species, areas were surveyed that contained similar native plant species cover, diversity and floral composition, with or without the invaders. Both invasive plant species received significantly more pollinator visits than any native species and invaders interacted strongly with pollinators. Overall, the pollinator community richness was similar in invaded and uninvaded plots, and only a few generalist pollinators visited invasive species exclusively. Invasive plants acted as pollination super generalists. The two species studied were visited by 43% and 31% of the total insect taxa in the community, respectively, suggesting they play a central role in the plant–pollinator networks. Carpobrotus and Opuntia had contrasting effects on pollinator visitation rates to native plants: Carpobrotus facilitated the visit of pollinators to native species, whereas Opuntia competed for pollinators with native species, increasing the nestedness of the plant–pollinator network. These results indicate that the introduction of a new species to a community can have important consequences for the structure of the plant–pollinator network.     

What is the potential of spread in invasive bryophytes?

Although the number of invasive bryophytes is much lower than that of higher plants, they threaten habitats that are often species rich and of high conservation relevance. Their potential of spread has, however, never been determined. Here, we assess whether the three most invasive bryophyte species shifted their niche during the invasion process and whether the extent of the study area defined to calibrate the model (geographic background, GB) affects model transferability. We then determine whether ecological niche models (ENMs) developed in their native range can be projected in other areas to assess their invasive potential. The macroclimatic niches of Campylopus introflexus, Orthodontium lineare and Lophocolea semiteres were compared in their native range (Southern Hemisphere) and in their invasion range (Northern Hemisphere) using ordination techniques. ENMs from an ensemble model were calibrated in the native range and projected onto the Northern Hemisphere using different GBs. No evidence for niche expansion in the invaded range was found and the species occur in the invaded range under climate conditions that are similar to those in the native range. The performance of the models to predict occurrences in the invaded range increased with the extent of the GB. The potential range of all species included entire regions on continents where they are still absent. The expansion of the investigated species appears to be constrained by climate conditions that are similar to those currently prevailing in their native range, which is consistent with our failure to demonstrate macroclimatic niche shift in the invaded range. The use of large GBs is recommended in such vagile organisms with large, disjunct distributions. The models indicated that invasive bryophyte species might become a threat in central and eastern Europe, North America and eastern Asia if accidentally introduced or naturally dispersed.     

Mesenchymal cells contribute to the synthesis and deposition of the laminin-5 γ2 chain in the invasive front of oral squamous cell carcinoma

Tumour progression in oral squamous cell carcinoma (OSCC) is associated with a reorganisation of extracellular matrix. Laminin-5 (Ln-5) plays an important role for tumour migration and shows an increased expression in areas of direct tumour/stroma interactions. We have previously shown stromal spot like Ln-5/γ2 chain deposits distant from the basement membrane region. In this study we have analysed which cell type is responsible for Ln-5/γ2 chain synthesis in situ. Furthermore, we studied its spatial relation to TGF-β1 as well as the Ln-5 modulating enzymes matrix metalloproteinase (MMP) 2, membrane type-1 (MT1-) MMP and bone morphogenetic protein (BMP-) 1 by different techniques including triple immunofluorescence labelling and in situ hybridisation in OSCC. We found that the stromal spot-like Ln-5 deposits occurred in the invasive front in the vicinity of mesenchymal cells and vessel structures. In particular, not only carcinoma cells but also mesenchymal cells were shown to express the Ln-5/γ2 chain mRNA. Moreover, stromal Ln-5 deposits showed a spatial association with TGF-β1 as well as with MT1-MMP and BMP-1. Based on these findings we suggest that mesenchymal cells contribute to the promotion of tumour cell migration as well as vessel formation in OSCC by providing and organising promigratory Ln-5 fragments.     

Complex formation of the laminin-5 γ2 chain and large unspliced tenascin-C in oral squamous cell carcinoma in vitro and in situ: implications for sequential modulation of extracellular matrix in the invasive tumor front

Invasion and metastasis in oral squamous cell carcinoma (OSCC) are associated with changes in the extracellular matrix (ECM). We have previously shown an extracellular co-deposition of laminin-5 (Ln-5) and large unspliced tenascin-C (Tn-C_L) in OSCC. Using a co-culture model of hTERT-BJ1 fibroblasts and the OSCC cell line PE/CA-PJ15, we demonstrate in the present study that Ln-5 and Tn-C_L are not only co-deposited, but also form a physical complex which can be recovered by co-immunoprecipitation. In agreement with these results, examination of OSCC tissue specimens of different malignancy grade by means of confocal laser scanning microscopy revealed different patterns of Ln-5 and Tn-C_L co-localization implicating complex formation also in vivo. A ribbon like co-localization was detected in subepithelial basement membranes around well differentiated OSCC parts and tumor clusters. Furthermore, a fibrillar Ln-5 γ2 chain/Tn-C_L co-localization occurred in the carcinoma stroma beneath tumor clusters. Additionally, at the site of ruptured basement membranes there were dot or strand like co-deposits of both molecules, but co-localizations were only rarely detectable. These different patterns may reflect a sequential modulation and reorganization of the ECM in the tumor/stroma interface as it occurs in different stages of OSCC invasion.     

Did life history evolve in response to parasites in invasive populations of Melanoides tuberculata?

Enemy release and rapid evolution are often assumed to promote biological invasions. In the parthenogenetic snail Melanoides tuberculata, one invasive strain (MAD) was assumed to benefit from enemy release until a heavily parasitized population was found in Colombia (in the area of introduction). This population is prosperous despite important losses in the reproductive potential due to a high prevalence of a trematode that castrates snails. We studied genetic variation in life-history traits among five populations from the invaded area to test whether life histories had recently evolved in the parasitized population in such a way that snails have more chance to reproduce before being parasitized. We find significant genetic differences among populations, though they are not in the expected direction. Individuals from the parasitized population were smaller at birth, grew slower, and reproduced later and at a bigger size than individuals from the non-parasitized populations. We conclude that the life-history traits of this snail strain did not need to evolve in order to allow population renewal in the invaded area, even in the presence of parasites. This implies that enemy release and/or rapid evolution were not necessary for this strain to invade.     

Phenotype alteration in colon carcinoma cells: Effect of in vivo passage?

Summary A panel of rat colon adenocarcinoma cell lines (the Per series) were used to investigate the phenotype and karyotype changes induced by in vivo passage in the subcutis of athymic nude mice. One poorly and one well-differentiated tumor cell line were serially passaged through the athymic nude mouse and then back to the syngeneic rat host. Each of the primary and xenograft cell lines expressed fetal crypt cell (“CaCo”) antigens. The well differentiated primary and xenograft lines (Per305, Per305N1, and Per305N2a) were different in each of their growth factor reponsiveness in vitro [i.e. epidermal growth factor (EGF), bombesin, vasoactive intestinal peptide], their EGF receptor expression, their secretion of transforming growth factor-α, and their exhibition of anchorage independent (A-I) growth capabilities. The poorly differentiated primary and xenograft cell lines were also different but were all capable of A-I growth; their responsiveness to exogenous growth factor stimulation decreased with progressive in vivo passage, as did their basal unstimulated proliferation rate. Cytogenetic alterations detected were those associated with clinical specimens from various stages of malignancy, i. e. aneuploidy, structural aberrations, and marker chromosomes. Genetic and mitogenic individuality of each line demonstrated the diversity of the growth control mechanisms in neoplasms at different stages of progression. Financial support was provided from the Richard Walter Gibbon Fund of the Faculty of Medicine, the University of Western Australia; and from the Sir Charles Gairdner Hospital Research Foundation.     

The native–invasive balance: implications for nutrient cycling in ecosystems

We conducted single- and mixed-litter experiments in a hardwood forest in Long Island, New York, using leaf litter from phylogenetically paired native and invasive species. We selected long-established, abundant invasive species with wide-ranging distributions in the eastern United States that likely make substantial contributions to the litter pool of invaded areas. Overall, leaf litter from invasive species differed from native litter, though differences varied by phylogenetic grouping. Invasive litter had lower carbon:nitrogen ratios (30.9 ± 1.96 SE vs. 32.8 ± 1.36, P = 0.034) and invasive species lost 0.03 ± 0.007 g of nitrogen and had 23.4 ± 4.9 % of their starting mass remaining at the end of 1 year compared with a loss of 0.02 ± 0.003 g nitrogen and 31.1 ± 2.6 % mass remaining for native species. Mixing litter from two species did not alter decomposition rates when native species were mixed with other native species, or when invasive species were mixed with other invasive species. However, mixing litter of native and invasive species resulted in significantly less mass and nitrogen loss than was seen in unmixed invasive litter. Mixtures of native and invasive litter lost all but 47 ± 2.2 % of initial mass, compared to 37 ± 5.8 % for invasive litter and 50 ± 5.1 % for native litter. This non-additive effect of mixing native and invasive litter suggests that an additive model of metabolic characteristics may not suffice for predicting invasion impacts in a community context, particularly as invasion proceeds over time. Because the more rapid decomposition of invasive litter tends to slow to rates typical of native species when native and invasive litters are mixed together, there may be little impact of invasive species on nutrient cycling early in an invasion, when native leaf litter is abundant (providing litter deposition is the dominant control on nutrient cycling).     

Secular trends of HPV genotypes in invasive cervical cancer in Cali,Colombia 1950–1999

Aim To estimate relative contribution and time trends of HPV types in cervical cancer in Cali, Colombia over a 50 years’ period.MethodsParaffin blocks of 736 cervical cancer histological confirmed cases were retrieved from the pathology laboratory at Hospital Universitario del Valle (Cali, Colombia) and HPV genotyped using SPF10-PCR/DEIA/LiPA25 (version 1) assay. Marginal effect of age and year of diagnosis in secular trends of HPV type prevalence among HPV+ cases were assessed by robust Poisson regression analysis.Results64.7% (95%CI: 59.9–69.2) of squamous cell carcinomas (SCCs) were attributed to HPV 16 and 18, 78.2% (95%CI: 74–82) to HPV 16, 18, 31, 33 and 45 and 84.8% (95%CI: 81–88.1) to HPV 16, 18, 31, 33, 45, 52 and 58 while ninety-three percent of adenocarcinomas (ADCs) were attributed to HPV 16, 18 and 45 only. The prevalence of specific HPV types did not change over the 50-year period. A significant downward trend of prevalence ratios of HPV16 (​P = 0.017) and α7 but HPV 18 (i.e., HPV 39, 45, 68, 70, ​P = 0.024) with increasing age at diagnosis was observed. In contrast, the prevalence ratio to other HPV genotypes of α9 but HPV 16 genotypes (i.e., HPV 31, 33, 35, 52, 58, 67, ​P = 0.002) increased with increasing age at diagnosis.ConclusionNo changes were observed in the relative contribution of HPV types in cervical cancer in Cali, Colombia during the 50 years. In this population, an HPV vaccine including the HPV 16, 18, 31, 33, 45, 52 and 58 genotypes may have the potential to prevent ∼85% and 93% of SCC and ADC cases respectively.     

Epithelial–mesenchymal transition induced cancer-stem-cell-like characteristics in hepatocellular carcinoma

Hepatocellular carcinoma in China accounts for half of the world's incidence. Both epithelial–mesenchymal transition (EMT) and cancer stem cells (CSCs) are thought to be involved in tumor malignant progression. However, the relationship between EMT and CSCs is still unclear. Bioinformatics analysis was performed to evaluate the relationship between EMT and CSCs. The EMT and CSC regulatory mechanism was investigated through Transwell, wound-healing, sphere formation, colony-forming, and western blotting assays. Immunofluorescence and immunoprecipitation were used to study the interaction of hypoxia inducible factor 1α (HIF-1α) /Notch1. Immunohistochemical study was applied to investigate the expression pattern in the process of hepatocellular carcinogenesis and development. In our present study, bioinformatics results indicate that the expression of EMT-related molecules is correlated with CSCs. In vitro studies indicated that EMT activation could induce CSC characteristics. Notch1 was confirmed to mediate the process of EMT-induced CSCs through the interaction with HIF-1α directly. Our findings indicate that EMT could induce CSC-like characteristics, which is mediated by HIF-1α-upregulated Notch intracellular domain expression.     

Do invasive freshwater fish species grow better when they are invasive?

A frequent assumption in invasion ecology is that invasive species have enhanced growth rates in their invasive ranges. However, invasions frequently occur in sub‐tropical and tropical environments where growth could be higher simply due to climatic conditions rather than novel habitat. In this study, a meta‐analysis of growth rates (length‐at‐age data) was completed for six invasive freshwater fish species: common carp Cyprinus carpio, largemouth bass Micropterus salmoides, brown trout Salmo trutta, brown bullhead Ictalurus nebulosus, flathead catfish Pylodictis olivaris and northern snakehead Channa argus. Significant effects of climate on growth were observed for all species except common carp, and following normalization of growth for climate effects, a range of growth responses between native and invasive populations were revealed. Two species (brown trout, flathead catfish) showed significantly increased growth rates in invasive compared to native ranges, but two species (common carp, largemouth bass) showed significantly faster growth in native ranges, and two other species (northern snakehead, brown bullhead) showed no difference in growth rates. No species showed both significantly enhanced growth rates and initial sizes in invasive compared to native ranges. Using the comparative method, countergradient growth variations were apparent for all species within their native ranges and for all but one species in invasive ranges. Invasive populations of freshwater fish do not always grow faster when invasive and future studies need to consider growth covariates (e.g. climate and countergradient growth) prior to comparing life‐history differences between invasive and native populations.     

Myrmica specioides Bondroit: a new invasive ant species in the USA?

Ants are among the most successful invasive species. The establishment of the infamous red imported fire ant Solenopsis invicta (Fabricius) has caused a considerable amount of damage to both the economy and the native ecosystem of the Southern United States. We report the first record of a newly introduced ant species, Myrmica specioides Bondroit, to the state of Washington. It possesses the characteristics of a potential pest ant: high aggressiveness, polygyny, and the tendency to reach high local abundances. This early record might facilitate the control of introduced populations before they can develop into a genuine nuisance.     

Has the invasive round goby caused new links in Baltic food webs?

The Ponto-Caspian round goby (Neogobius melanostomus, Pallas 1814) most probably was established in the Gulf of Gdańsk, Baltic Sea, in the late 1980’s and has since become one of the dominant species in the region. In this study we assess the role of round gobies as prey for two important fish species in the Gulf of Gdańsk, cod (Gadus morhua) and perch (Perca fluviatilis). We compared their present diet with stomach analyses from the area prior the round goby establishment, as well as with diet analysis from Baltic regions where round gobies are absent. There were large differences in the diet between cods from the Gulf of Gdańsk 2003–2006 compared to cods in earlier studies (1977–1981) from the Southern Baltic Sea. There were also large differences in cod and perch diets from areas with and without round goby. Presently, round goby constitutes the most important prey for medium sized cods in Gulf of Gdańsk, and perch from the same area almost exclusively feed on gobiids. Stomach analysis, trophic level estimates, and stable isotope analyses all indicated that cod and perch in Gulf of Gdańsk after the round goby establishment belonged to a similar trophic level. Beside round goby, no mussel feeding fish contributed much to the diet of cod or at all to the diet of perch. Thus, it is likely that round gobies constitute a new energetic pathway from mussels to top predators. However, due to the short time elapsed after round goby establishment, we can only speculate on the species future impacts on Baltic food webs.     

Oncocytic-type intraductal papillary mucinous neoplasm (IPMN)-derived invasive oncocytic pancreatic carcinoma with brain metastasis ¿ a case report

ABSTRACT: Pancreatic cancer is a lethal disease without effective treatments at present. It ranks as s as 4th and 5th in cancer-related mortality in the western countries and worldwide. Locally advanced pancreatic duct carcinoma (PDAC) and metastatic PDAC, usually found the metastases over liver, peritoneum, or lung, have been shown to be with dismal prognosis. Brain metastasis is a rare entity and most cases reported before were found post-mortem. Intraductal papillary mucinous neoplasms of the pancreas (IPMN) has been deemed as a precursor of PDAC with very slow progression rate. Here we reported a case diagnosed with IPMN-derived PDAC with brain metastasis. After surgeries for PDAC and brain metastasis, subsequent chemotherapy and radiotherapy were also given. One and half year after surgery, this patient is still living with good performance status, which may warrant individualization of therapeutic strategy for PDAC with only brain metastasis.     

Do invasive plants structure microbial communities to accelerate decomposition in intermountain grasslands?

Invasive plants are often associated with greater productivity and soil nutrient availabilities, but whether invasive plants with dissimilar traits change decomposer communities and decomposition rates in consistent ways is little known. We compared decomposition rates and the fungal and bacterial communities associated with the litter of three problematic invaders in intermountain grasslands; cheatgrass (Bromus tectorum), spotted knapweed (Centaurea stoebe) and leafy spurge (Euphorbia esula), as well as the native bluebunch wheatgrass (Pseudoroegneria spicata). Shoot and root litter from each plant was placed in cheatgrass, spotted knapweed, and leafy spurge invasions as well as remnant native communities in a fully reciprocal design for 6 months to see whether decomposer communities were species‐specific, and whether litter decomposed fastest when placed in a community composed of its own species (referred to hereafter as home‐field advantage–HFA). Overall, litter from the two invasive forbs, spotted knapweed and leafy spurge, decomposed faster than the native and invasive grasses, regardless of the plant community of incubation. Thus, we found no evidence of HFA. T‐RFLP profiles indicated that both fungal and bacterial communities differed between roots and shoots and among plant species, and that fungal communities also differed among plant community types. Synthesis. These results show that litter from three common invaders to intermountain grasslands decomposes at different rates and cultures microbial communities that are species‐specific, widespread, and persistent through the dramatic shifts in plant communities associated with invasions.     

Pre-adaptation or genetic shift after introduction in the invasive species Impatiens glandulifera?

Invasive exotic plants often grow fast, reproduce rapidly and display considerable phenotypic plasticity in their invasive range, which may be essential characteristics for successful invasion. However, it remains unclear whether these characteristics are already present in native populations (pre-adaptation hypothesis) or evolve after introduction (genetic shift hypothesis).To test these hypotheses we compared means and phenotypic plasticity of vegetative and reproductive traits between populations of Impatiens glandulifera collected from either the invasive (Norway) or native range (India). Seeds were sown and the resulting plants were exposed to different experimental environments in a glasshouse. We also tested whether trait means and reaction norms harbored genetic variation, as this may promote fitness in the novel environment.We did not find evidence that invasive populations of I. glandulifera grew more vigorously or produced more seeds than native populations. Phenotypic plasticity did not differ between the native and invasive range, except for the number of nodes which was more plastic in the invasive range. Genetic variation in the slope of reaction norms was absent, suggesting that the lack of change in phenotypic plasticity between native and invasive populations resulted from low genetic variation in phenotypic plasticity initially harbored by this species. Post-introduction evolution of traits thus probably did not boost the invasiveness of I. glandulifera. Instead, the species seems to be pre-adapted for invasion.We suggest that differences in habitat between the native and invasive range, more specifically the higher nutrient availability observed in the new environment, are the main factor driving the invasion of this species. Indeed, plants in the more nutrient-rich invasive range had greater seed mass, likely conferring a competitive advantage, while seed mass also responded strongly to nutrients in the glasshouse. Interactions between habitat productivity and herbivore defense may explain the lack of more vigorous growth in the new range.