Degree Of Phenotypic Plasticity Research Articles

Chronic Thermal Acclimation Effects on Critical Thermal Maxima (CTmax) and Oxidative Stress Differences in White Epaxial Muscle between Surface and Cave Morphotypes of the Mexican Cavefish (Astyanax mexicanus).

AbstractIn the face of increasing environmental temperatures, operative differences between mitochondrial function and whole-animal phenotypic response to the environment are underrepresented in research, especially in subtemperate ectothermic vertebrates. A novel approach to exploring this connection is to examine model species that are genetically similar but that have different whole-animal phenotypes, each of which inhabits different environments. The blind Mexican cavefish (Astyanax mexicanus) has the following two morphotypes: a surface form found in aboveground rivers and an obligate cave-dwelling form. Each morphotype inhabits vastly different thermal and oxygen environments. Whole-animal and mitochondrial responses to thermal acclimation and oxidative stress, with respect to increasing temperatures, have not been previously determined in either morphotype of this species. Here, we chronically acclimated both morphotypes to three temperatures (14°C, 25°C, and 31°C) to establish potential for acclimation and critical thermal maxima (CTmax) for each morphotype of this species. After measuring CTmax in six cohorts, we additionally measured enzymatic antioxidant capacity (catalase, superoxide dismutase, and glutathione peroxidase activities), peroxyl scavenging capacity, and lipid peroxidation damage in white epaxial muscle for each individual. We found a significant effect of acclimation temperature on CTmax (, ) but no effect of morphotype on CTmax (, ). Additionally, we found that morphotype had a significant effect on glutathione peroxidase activity, with the surface morphotype having increased glutathione peroxidase activity compared with the cave morphotype (, ). No other oxidative stress variable demonstrated significant differences. Increases in CTmax with chronic thermal acclimation to higher temperatures suggests that there is some degree of phenotypic plasticity in this species that nominally occupies thermally stable environments. The decreased glutathione peroxidase activity in the cave morphotype may be related to decreased environmental oxygen concentration and decreased metabolic rate in this environmentally constrained morphotype compared to in its surface-living counterparts.

Multilevel selection in the evolution of sexual dimorphism in phenotypic plasticity.

Phenotypes are partly shaped by the environment, which can impact both short-term adaptation and long-term evolution. In dioecious species, the two sexes may exhibit different degrees of phenotypic plasticity and theoretical models indicate that such differences may confer an adaptive advantage when the population is subject to directional selection, either because of a systematically varying environment or a load of deleterious mutations. The effect stems from the fundamental asymmetry between the two sexes: female fertility is more limited than male fertility. Whether this asymmetry is sufficient for sexual dimorphism in phenotypic plasticity to evolve is, however, not obvious. Here, we show that even in conditions where it provides an adaptive advantage, dimorphic phenotypic plasticity may be evolutionarily unstable due to sexual selection. This is the case, in particular, for panmictic populations where mating partnerships are formed at random. However, we show that the effects of sexual selection can be counteracted when mating occurs within groups of related individuals. Under this condition, sexual dimorphism in phenotypic plasticity can not only evolve but offset the twofold cost of males. We demonstrate these points with a simple mathematical model through a combination of analytical and numerical results.

Abstract P175: In Vitro Cholesterol Treatment Does Not Reproduce Smooth Muscle Cell Phenotypic Plasticity Observed In Vivo

Vascular Smooth Muscle Cells (SMCs) exhibit a significant degree of phenotypic plasticity in atherosclerotic lesions. Previously, this phenotypic plasticity, and specifically the re-differentiation of SMCs into macrophages, has been modeled in vitro using cholesterol treatment. We performed a meta-analysis of five different murine SMC lineage tracing single-cell RNA sequencing (scRNA-seq) experiments performed by four different research groups; we identified 24 different cell types and find considerable differences in the proportion of recovered normal ‘contractile’ SMCs and SMC-derived macrophages between experiments. In addition, we performed bulk RNA-seq on cultured murine SMCs with and without cholesterol treatment for 0, 24, or 48 hours. We find that cholesterol treatment regulates transcripts associated with the induction of the unfolded protein response, reduction of cholesterol biosynthesis, and reduction in cell proliferation. Additionally, chromatin immunoprecipitation followed by high-throughput sequencing for H3K27ac performed on in vitro SMCs treated and untreated for 0, 24, or 48 hours reveals that AP-1 and ATF4 binding motifs are found more frequently at cholesterol treatment specific H3K27ac chromatin sites. Finally, we compared transcriptomic data between in vivo vascular cell types identified in our meta-analysis and in vitro SMCs. We additionally included scRNA-seq data and microarray data collected for in vitro SMCs and bulk RNA-seq data collected for M1, M2, and oxLDL treated macrophages. We find that compared to the phenotypic plasticity observed in vivo, cholesterol exhibits modest effects on the transcriptomes of in vitro SMCs and does not reproduce the changes observed in vivo, while in vitro macrophages, especially oxLDL treated macrophages, more closely approximate their in vivo counterparts. We conclude that differences between SMC lineage-tracing scRNA-seq experiments obscures the degree to which SMC-derived macrophages are present in murine atherosclerotic plaques, that cholesterol has modest effects on in vitro SMC transcriptomes, and that the effects of cholesterol do not reproduce the phenotypic plasticity observed in vivo.

Consequences of Captive-Rearing and Exposure to Cues from Potential Predators on Shell Sizes and Shapes of North American Stagnicoline Gastropods (Family Lymnaeidae)

Understanding the extent to which traits that are used to delimit and diagnose species are phenotypically plastic is important for recognizing species boundaries. Shell characters have long been used for describing species of gastropods, even though these features may be influenced by environmental conditions. To determine the degree of phenotypic plasticity of two North American lymnaeid species, Stagnicola elodes (Say, 1821) and Stagnicola emarginata (Say, 1821), that occur in different habitats and differ in shell morphology, we reared individuals in captivity under similar conditions and compared shell shapes and sizes of wild-caught and captive-reared populations. We also exposed individuals of S. elodes to effluent from a potential predator (crayfish) to gauge the possible impact of the presence of predators on shell morphology. Although the two species remained morphologically distinct, shell shapes of captive-reared individuals of both species differ significantly from those of wild-caught individuals and show similar magnitudes of change among species. Directions of change, however, differed significantly among species. Although shell shapes of individuals of S. elodes that were exposed to crayfish cues were not significantly different from control snails, shell sizes of exposed snails were smaller than unexposed snails. These results suggest that exposure to predators affects growth rates of S. elodes. Nonetheless, given significant associations between shell shape and size that were observed in the captive-rearing and predator-exposure experiments, shell shape changes allometrically during development. These results suggest that morphological differences of other North American Stagnicola species reflect ecophenotypic variation, but more work is necessary to further evaluate this hypothesis.

Divergent scute asymmetry among pure and crossed individuals of Testudo hermanni (Gmelin, 1789)

Fluctuating asymmetry (FA) refers to subtle differences between left and right sides in bilaterally symmetrical organisms or their parts. Both genetic and environmental changes can increase FA, reflecting deterioration in developmental homeostasis of adult morphology due to a loss of developmental stability. In this study, we used geometric morphometric techniques to examine plastral scute asymmetries in a sample of 31 pure and crossed Testudo species (T. hermanni hermanni n = 23 and crosses with T. hermanni boettgeri n = 8) only females by means of 19 anatomical landmarks. Procrustes ANOVA indicated that FA in crossed individuals was significantly higher than that in pure individuals. Crossed individuals also showed a greater degree of phenotypic plasticity than T. hermanni hermanni. We conclude that crosses among T. hermanni hermanni and T. hermanni boettgeri can increase homozygosity and are responsible for greater developmental instabilities. Nonetheless, more information on crossed phenotypes could be of great interest to raise pure Hermann’s tortoises for reintroduction programmes. Key words: Carapace, Geometric morphometrics, Hybridization, Plastron, Testudines

Expression of alternative developmental pathways in the cabbage butterfly, Pieris melete and their differences in life history traits.

The seasonal life cycle of the cabbage butterfly, Pieris melete is complicated because there are three options for pupal development: summer diapause, winter diapause, and nondiapause. In the present study, we tested the influence of temperature, day length, and seasonality on the expression of alternative developmental pathways and compared the differences in life history traits between diapausing and directly developing individuals under laboratory and field conditions. The expression of developmental pathway strongly depended on temperature, day length, and seasonality. Low temperatures induced almost all individuals to enter diapause regardless of day length; relatively high temperatures combined with intermediate and longer day lengths resulted in most individuals developing without diapause in the laboratory. The field data revealed that the degree of phenotypic plasticity in relation to developmental pathway was much higher in autumn than in spring. Directly developing individuals showed shorter development times and higher growth rates than did diapausing individuals. The pupal and adult weights for both diapausing and directly developing individuals gradually decreased as rearing temperature increased, with the diapausing individuals being slightly heavier than the directly developing individuals at each temperature. Female body weight was slightly lower than male body weight. The proportional weight losses from pupa to adult were almost the same in diapausing individuals and in directly developing individuals, suggesting that diapause did not affect weight loss at metamorphosis. Our results highlight the importance of the expression of alternative developmental pathways, which not only synchronizes this butterfly's development and reproduction with the growth seasons of the host plants but also exhibits the bet‐hedging tactic against unpredictable risks due to a dynamic environment.

Comparing the behavioural thermoregulation response to heat stress by Atlantic salmon parr (Salmo salar) in two rivers

AbstractClimate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon (Salmo salar) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature surpasses this threshold, juvenile salmon exploit thermal heterogeneity to behaviourally thermoregulate, forming aggregations in coolwater refuges. This study aimed to determine whether the behavioural thermoregulation response is universal across rivers, arising from common thermal cues. We detailed the temperature and discharge patterns of two geographically distinct rivers from 2010 to 2012 and compared these with aggregation onset temperature. PIT telemetry and snorkelling were used to confirm the presence of aggregations. Mean daily maximum temperature in 2010 was significantly greater in the OR versus the LSWM (p = 0.005), but not in other years (p = 0.090–0.353). Aggregations occurred on 14 and 9 occasions in the OR and LSWM respectively. Temperature at onset of aggregation was significantly greater in the OR (Tonset = 28.3°C) than in the LSWM (Tonset = 27.3°C; p = 0.049). Logistic regression models varied by river and were able to predict the probability of aggregation based on the preceding number of hours >23°C (R2 = 0.61 & 0.65; P50 = 27.4°C & 28.9°C; in the OR and LSWM respectively). These results imply the preceding local thermal regime may influence behaviour and indicate a degree of phenotypic plasticity, illustrating a need for localised management strategies.

Natural selection on plasticity of thermal traits in a highly seasonal environment.

For ectothermic species with broad geographical distributions, latitudinal/altitudinal variation in environmental temperatures (averages and extremes) is expected to shape the evolution of physiological tolerances and the acclimation capacity (i.e., degree of phenotypic plasticity) of natural populations. This can create geographical gradients of selection in which environments with greater thermal variability (e.g., seasonality) tend to favor individuals that maximize performance across a broader range of temperatures compared to more stable environments. Although thermal acclimation capacity plays a fundamental role in this context, it is unknown whether natural selection targets this trait in natural populations. Additionally, understanding whether and how selection acts on thermal physiological plasticity is also highly relevant to climate change and biological conservation. Here, we addressed such an important gap in our knowledge in the northernmost population of the four‐eyed frog, Pleurodema thaul. We measured plastic responses of critical thermal limits for activity, behavioral thermal preference, and thermal sensitivity of metabolism to acclimation at 10 and 20°C. We monitored survival during three separate recapture efforts and used mark‐recapture integrated into an information‐theoretic approach to evaluate the relationship between survivals as a function of the plasticity of thermal traits. Overall, we found no evidence that thermal acclimation in this population is being targeted by directional selection, although there might be signals of selection on individual traits. According to the most supported models, survival increased in individuals with higher tolerance to cold when cold‐acclimated, probably because daily low extremes are frequent during the cooler periods of the year. Furthermore, survival increased with body size. However, in both cases, the directional selection estimates were nonsignificant, and the constraints of our experimental design prevented us from evaluating more complex models (i.e., nonlinear selection).

Enigmatic ear stones: what we know about the functional role and evolution of fish otoliths.

Otoliths in bony fishes play an important role in the senses of balance and hearing. Otolith mass and shape are, among others, likely to be decisive factors influencing otolith motion and thus ear functioning. Yet our knowledge of how exactly these factors influence otolith motion is incomplete. In addition, experimental studies directly investigating the function of otoliths in the inner ear are scarce and yield partly conflicting results. Herein, we discuss questions and hypotheses on how otolith mass and shape, and the relationship between the sensory epithelium and overlying otolith, influence otolith motion. We discuss (i) the state-of-the-art knowledge regarding otolith function, (ii) gaps in knowledge that remain to be filled, and (iii) future approaches that may improve our understanding of the role of otoliths in ear functioning. We further link these functional questions to the evolution of solid teleost otoliths instead of numerous tiny otoconia as found in most other vertebrates. Until now, the selective forces and/or constraints driving the evolution of solid calcareous otoliths and their diversity in shape in teleosts are largely unknown. Based on a data set on the structure of otoliths and otoconia in more than 160 species covering the main vertebrate groups, we present a hypothetical framework for teleost otolith evolution. We suggest that the advent of solid otoliths may have initially been a selectively neutral 'by-product' of other key innovations during teleost evolution. The teleost-specific genome duplication event may have paved the way for diversification in otolith shape. Otolith shapes may have evolved along with the considerable diversity of, and improvements in, auditory abilities in teleost fishes. However, phenotypic plasticity may also play an important role in the creation of different otolith types, and different portions of the otolith may show different degrees of phenotypic plasticity. Future studies should thus adopt a phylogenetic perspective and apply comparative and methodologically integrative approaches, including fossil otoliths, when investigating otoconia/otolith evolution and their function in the inner ear.

Molecular phylogeny and morphological diversity of inland Cladophora (Cladophorales, Ulvophyceae) from China

:Cladophora has a global distribution and provides a habitat and food for numerous organisms. However, the taxonomy of Cladophora is confusing and poorly defined. In this study, 69 freshwater and brackish-water Cladophora samples from inland China were collected, and both morphological and phylogenetic analyses of these samples were performed. The concatenated molecular phylogenies based on ribosomal DNA sequences showed that these inland samples belonged to two groups: freshwater Cladophora and non-freshwater Cladophora. The phylogenetic results showed that there were eight clades in the freshwater group. The results of morphological observation showed characteristic similarities among the clades, and the samples in each clade exhibited different degrees of phenotypic plasticity. The prediction model for internal transcribed spacer 2 secondary structure showed that freshwater Cladophora contain one ring structure with three main helices (helices I–III), in which the helix III-2 region was most variable. The high phenotypic plasticity and lack of diagnostic characteristics of the freshwater Cladophora group made delineating species difficult and challenging. Further sampling from a broader range in combination with more efficient molecular markers are necessary to clarify the taxonomy of Cladophora in the future.

The spatial scale of local adaptation in a stochastic environment.

The distribution of phenotypes in space will be a compromise between adaptive plasticity and local adaptation increasing the fit of phenotypes to local conditions and gene flow reducing that fit. Theoretical models on the evolution of quantitative characters on spatially explicit landscapes have only considered scenarios where optimum trait values change as deterministic functions of space. Here, these models are extended to include stochastic spatially autocorrelated aspects to the environment, and consequently the optimal phenotype. Under these conditions, the regression of phenotype on the environmental variable becomes steeper as the spatial scale on which populations are sampled becomes larger. Under certain deterministic models - such as linear clines - the regression is constant. The way in which the regression changes with spatial scale is informative about the degree of phenotypic plasticity, the relative scale of effective gene flow and the environmental dependency of selection. Connections to temporal models are discussed.

Ecological genetics of range size variation in Boechera spp. (Brassicaceae).

Many taxonomic groups contain both rare and widespread species, which indicates that range size can evolve quickly. Many studies have compared molecular genetic diversity, plasticity, or phenotypic traits between rare and widespread species; however, a suite of genetic attributes that unites rare species remains elusive. Here, using two rare and two widespread Boechera (Brassicaceae) species, we conduct a simultaneous comparison of quantitative trait diversity, genetic diversity, and population structure among species with highly divergent range sizes. Consistent with previous studies, we do not find strong associations between range size and within-population genetic diversity. In contrast, we find that both the degree of phenotypic plasticity and quantitative trait structure (Q ST) were positively correlated with range size. We also found higher F ST: Q ST ratios in rare species, indicative of either a greater response to stabilizing selection or a lack of additive genetic variation. While widespread species occupy more ecological and climactic space and have diverged at both traits and markers, rare species display constrained levels of population differentiation and phenotypic plasticity. Combined, our results provide evidence for a specialization-generalization trade-off across three orders of magnitude of range size variation in the ecological model genus, Boechera.

Pattern and variation of the time budget of yellow-bellied marmots

We measured the time budgets of yellow-bellied marmots to determine what constraints limited energy acquisition and whether trade-offs occurred among the behaviors. Therefore, we focus on which behaviors form a consistent pattern among marmot populations, the degree of phenotypic plasticity in the time allocated to the behaviors, and the biotic and abiotic factors associated with variations in time allocations. Time budgets for 14 behaviors were recorded at six sites in the Upper East River Valley in western Colorado over two active seasons. Data were analyzed for cohort, day-period and season-period, and for interactions among the main effects. Sitting and vigilance, accounting for 63% of aboveground activity, are strongly associated with wariness, the need for marmots to monitor the presence of conspecific and predatory intruders. Foraging accounts for 15% of daily activity. These three activities are the major contributors to time budgets at all sites. Radiation, acting as a thermal constraint, greatly reduces activity during mid-day when radiation is intense. Sitting is the only major behavior to increase at mid-day, presumably to maintain wariness. Time allocations change little over the season-periods and foraging does not significantly increase in the weeks prior to hibernation. Young generally are less vigilant, often spend less time sitting and forage less than adults, but generally allocate more minutes to investigation. Time is a seasonal but not a daily constraint. Thermal constraints reduce overall daily activity, and digestive constraints limit foraging time. Sitting provides a reservoir of time that can be drawn upon when needed for other behaviors such that costly trade-offs are not evident. Time allocations for an activity may differ among sites; these differences and most significant differences, whether for cohort, day-period or season-period, are associated with the behaviors of a particular age/sex group, such as high time allocation to investigation by immigrant males.

The phenotypic variance gradient - a novel concept.

Evolutionary ecologists commonly use reaction norms, which show the range of phenotypes produced by a set of genotypes exposed to different environments, to quantify the degree of phenotypic variance and the magnitude of plasticity of morphometric and life-history traits. Significant differences among the values of the slopes of the reaction norms are interpreted as significant differences in phenotypic plasticity, whereas significant differences among phenotypic variances (variance or coefficient of variation) are interpreted as differences in the degree of developmental instability or canalization. We highlight some potential problems with this approach to quantifying phenotypic variance and suggest a novel and more informative way to plot reaction norms: namely “a plot of log (variance) on the y-axis versus log (mean) on the x-axis, with a reference line added”. This approach gives an immediate impression of how the degree of phenotypic variance varies across an environmental gradient, taking into account the consequences of the scaling effect of the variance with the mean. The evolutionary implications of the variation in the degree of phenotypic variance, which we call a “phenotypic variance gradient”, are discussed together with its potential interactions with variation in the degree of phenotypic plasticity and canalization.

Collective and individual migration following the epithelial-mesenchymal transition.

During cancer progression, malignant cells in the tumour invade surrounding tissues. This transformation of adherent cells to a motile phenotype has been associated with the epithelial mesenchymal transition (EMT). Here, we show that EMT-activated cells migrate through micropillar arrays as a collectively advancing front that scatters individual cells. Individual cells with few neighbours dispersed with fast, straight trajectories, whereas cells that encountered many neighbours migrated collectively with epithelial biomarkers. We modelled these emergent dynamics using a physical analogy to solidification phase transitions in binary mixtures, and validated it using drug perturbations, which revealed that individually migrating cells exhibit diminished chemosensitivity. Our measurements also indicate a degree of phenotypic plasticity as cells interconvert between individual and collective migration. The study of multicellular behaviours with single-cell resolution should enable further quantitative insights into heterogeneous tumour invasion.

Climatic effects and phenological mismatch in cuckoo–host interactions: a role for host phenotypic plasticity in laying date?

Climatic effects on breeding phenology vary across organisms and therefore might promote a phenological mismatch in ecologically interacting species, including those engaged in coevolutionary interactions such as brood parasites and their hosts. Recent studies suggest that climatic induced changes in migration phenology may have mismatched cuckoos and their hosts in Europe. However, it is currently unknown whether cuckoo–host phenological mismatch results from different degrees of phenotypic plasticity or to different speeds of microevolutionary processes affecting hosts and parasites. Here we performed 1) cross‐sectional correlations between climate conditions and population level of phenological mismatch between the migratory brood parasite great spotted cuckoo Clamator glandarius and its main resident host in Europe, the magpie Pica pica; and 2) a longitudinal analysis to study within‐individual variation in breeding phenology for individual hosts experiencing different climate conditions over a period of nine years (2005–2013). Cross‐sectional analyses revealed independent and contrary effects of winter and spring temperature on magpie phenology: magpie hosts tend to breed earlier those years with lower February temperatures, however, high temperature in the first half of April spur individuals to lay eggs. Breeding phenology of cuckoos was tuned to that of their magpie host in time and duration. However, annual phenological mismatch between cuckoos and magpie hosts increased with NAO index and January temperature. Longitudinal analyses revealed high individual consistency in magpie host phenology, but a low influence of climate, suggesting that the climatic‐driven phenological mismatch between cuckoos and magpies at the population‐level cannot be explained by a host plastic response to climatic conditions.

Morphological change and phenotypic plasticity in native and non-native pumpkinseed sunfish in response to competition.

Non-indigenous species are oftentimes exposed to ecosystems with unfamiliar species, and organisms that exhibit a high degree of phenotypic plasticity may be better able to contend with the novel competitors that they may encounter during range expansion. In this study, differences in morphological plasticity were investigated using young-of-year pumpkinseed sunfish (Lepomis gibbosus) from native North American and non-native European populations. Two Canadian populations, isolated from bluegill sunfish (L. macrochirus) since the last glaciation, and two Spanish populations, isolated from bluegill since their introduction in Europe, were reared in a common environment using artificial enclosures. Fish were subjected to allopatric (without bluegill) or sympatric (with bluegill) conditions, and differences in plasticity were tested through a MANOVA of discriminant function scores. All pumpkinseed populations exhibited dietary shifts towards more benthivorous prey when held with bluegill. Differences between North American and European populations were observed in body dimensions, gill raker length and pelvic fin position. Sympatric treatments induced an increase in body width and a decrease in caudal peduncle length in native fish; non-native fish exhibited longer caudal peduncle lengths when held in sympatry with bluegill. Overall, phenotypic plasticity influenced morphological divergence less than genetic factors, regardless of population. Contrary to predictions, pumpkinseeds from Europe exhibited lower levels of phenotypic plasticity than Canadian populations, suggesting that European pumpkinseeds are more canalized than their North American counterparts.

Фенотипическая пластичность в соотношении полов у Idotea baltica basteri (Crustacea, Isopoda) в Одесском заливе Черного моря

The degree of phenotypic plasticity in the Idotea baltica basteri Audouin, 1827 (Crustacea, Isopoda) sex ratio of the fouling community in the Odessa bay of the Black Sea was determined. The ratio of males and females in three main phenotypes of I. baltica basteri, namely: uniformis, albafusca and lineata was found. Crustaceans were collected on the underwater surface of traverses, located in three sea districts with the different degrees of water exchange intensity with the open sea. Water depth at the wall of traverses ranged from 1 to2,5 m. In the first most opened district among the individuals of uniformis phenotype the ratio of males and females was equal to 1:4, that for albafusca – 1:1,3 and lineata – 1:1. In the second area with the release of drainage waters among the individuals of uniformis phenotype this ratio was equal to 1:4,5, while the albafusca and lineata figures were 1:1,5 and 1:1, accordingly. In the third region, with the most difficult water exchange, among the individuals of phenotypes the ratios of males and females were as follows: uniformis – 1:8, albafusca – 1:2, and lineata – 1:1. When moving from the opened to semi-enclosed area among the individuals of all phenotypes there was a gradual decline in the proportion of males and accordingly, increases of the proportion of females. The greatest number of males in all areas under study is observed among the individuals of lineata phenotype, and that of females – among the individuals of uniformis phenotype. It is found that monochromatic colored females prefer to stay in the shaded places among the seagrass beds and brightly colored males usually move actively along the outside of the substrata.

Phenotypic Plasticity of Southern Ocean Diatoms: Key to Success in the Sea Ice Habitat?

Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata) exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species’ known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem.

Novel Approaches For Targeted Therapy In Cutaneous T-Cell Lymphomas

IntroductionDevelopment of targeted therapy for Cutaneous T-Cell Lymphoma (CTCL) patients still requires actionable mutated genes and deregulated pathways to be identified and explored. Although it has been proposed that neoplastic CTCL cells feature increased TCR downstream signaling and also a degree of phenotypic plasticity, the mechanistic nature of the pathogenesis of this disease remains essentially unveiled. Our laboratory has recently studied the mutational status of a number of human CTCL lesions, and detected TCR/PLCG1 and JAK/STAT signaling pathways frequently mutated. Taking advantage of these findings, we have explored the biological effects that targeted inhibition, using specific inhibitors of the two afore mentioned signaling pathways, exerts in proliferation, survival and phenotype in a panel of human CTCL cell lines. Our results suggest that TCR/PLCG1 and JAK/STAT pathways can control proliferation, survival and phenotype of CTCL cells and hence can serve as potential targets for mono or combinatorial therapy in CTCL patients. Material and MethodsCutaneous T-cell lymphoma cell lines used were HH (MF) and MJ (MF) obtained from ATCC (Rockville, MD, US ) and My-La (MF) and HUT-78 (SS) obtained from ECACC (Salisbury, UK).Cell proliferation analyses were performed using CellTiter-Glo® Luminescent Cell Viability Assay kit (Promega, Madison, WI, USA) with the appropriate amount of inhibitor. Apoptosis were evaluated by flow cytometry using FlowCellect Annexin Red Kit (EMD Millipore Corporation, Billerica, USA). All data were detected on a FACS Calibur flow cytometer (BD) and analyzed using CellQuest Pro software (BD). Treg/Th17 phenotype was determined by flow cytometry. Cells were stained with monoclonal antibodies: anti-CD4-allophycocyanin (APC)-Cy7 (clone SK3, Becton Dickinson, San Diego, CA). Monoclonal antibodies to detect intracellular antigens were: anti-Foxp3-PE (clone PCH101, eBiosciences, San Diego, CA), anti-RORgt-APC (clone AFKJS-9, eBioscience, San Diego, CA), and IgG2a isotype controls conjugated with PE and APC. The cells were acquired by flow cytometer (FACS Canto-II, Becton Dickinson). ResultsTo test both the effect that inhibition of PLCG1 downstream signaling and the effect that inhibition of JAK downstream signaling provokes in CTCL cell lines, they were incubated with increasing concentrations of specific CaN and JAK inhibitors like FK506 and INCB018424 respectively or DMSO (vehicle) for 0, 24 and 48 h. The results show that increasing concentrations of FK506 affected the proliferation and survival of CTCL cells in a concentration dependent manner. But in the case of INCB018424 inhibitor mainly affects CTCL cell proliferation versus survival. The combined use of FK506 and INCB018424 produced a significant greater inhibition of CTCL cell proliferation than each inhibitor alone except of HUT-78, where the combined treatment was not significant (Figure 1). [Display omitted] Because of neoplastic T-cells can acquire Treg and/or Th17 phenotypes at different stages of the disease (Tiemessen, M.M. et al. 2006) and that there is a CTCL phenotypic plasticity(Abraham, Zhang et al. 2011) (Eisenstein and Williams 2009) (Hoechst, Gamrekelashvili et al. 2011), we have decided to study these phenotypes in the four CTCL cell lines. Strikingly we found that most cells in all CTCL cell lines were double positive for the expression of Treg and Th17 markers (Figure 2). [Display omitted] The expression of the Treg and Th17 lineage markers (FoxP3 and RORγt respectively) after treatment with FK506 and INCB018424 were tested. FK506 provoked an unbalance in the expression of the Treg and Th17 markers in all CTCL cell lines. (Figure 3). [Display omitted] ConclusionsThese results are the first evidences for the use of a combinatorial targeted therapy developed on the basis of a mutational analysis in CTCL, which in the future may serve as a lead to explore into detail about a potential utilization of this therapeutical approach in the clinic. Surprisingly, our results evidence a novel hybrid Treg/Th17 phenotype in our panel of CTCL cell lines, that we could alter by interfering specifically with TCR/PLCG1 and/or JAK/STAT downstream signaling using FK506 and/or INCB018424 respectively. Although these are still primary results, it will be important to explore how to take clinical advantage of these phenotypic characteristics in patients. Disclosures:No relevant conflicts of interest to declare.