How the interplay among the tumor microenvironment and the gut microbiota influences the stemness of colorectal cancer cells

Colorectal cancer(CRC)remains the third most prevalent cancer disease and involves a multi-step process in which intestinal cells acquire malignant characteristics.It is well established that the appearance of distal metastasis in CRC patients is the cause of a poor prognosis and treatment failure.Nevertheless,in the last decades,CRC aggressiveness and progression have been attributed to a specific cell population called CRC stem cells(CCSC)with features like tumor initiation capacity,self-renewal capacity,and acquired multidrug resistance.Emerging data highlight the concept of this cell subtype as a plastic entity that has a dynamic status and can be originated from different types of cells through genetic and epigenetic changes.These alterations are modulated by complex and dynamic crosstalk with environmental factors by paracrine signaling.It is known that in the tumor niche,different cell types,structures,and biomolecules coexist and interact with cancer cells favoring cancer growth and development.Together,these components constitute the tumor microenvironment(TME).Most recently,researchers have also deepened the influence of the complex variety of microorganisms that inhabit the intestinal mucosa,collectively known as gut microbiota,on CRC.Both TME and microorganisms participate in inflammatory processes that can drive the initiation and evolution of CRC.Since in the last decade,crucial advances have been made concerning to the synergistic interaction among the TME and gut microorganisms that condition the identity of CCSC,the data exposed in this review could provide valuable insights into the biology of CRC and the development of new targeted therapies.

Tropical tree community composition and diversity variation along a volcanic elevation gradient

Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology.This is especially true in areas where topography is complex due to volcano elevational gradients and where forests are vulnerable to human activity.In this study we used a set of climatic(temperature,rainfall,and radiation solar),topographic(elevation,slope aspect,and slope orientation)and human disturbance variables to determine their effect on diversity and composition patterns of a tree community,considering three slope aspects of a tropical volcano in southeastern Mexico.We sampled trees in seventy 0.1-ha plots distributed on three slope aspects of the Tacanávolcano along an elevational gradient of 1500 to 2500 m.We determined diversity patterns(general tree richness,exponential of Shannon index,and pioneer species richness)with linear regression models,and for beta diversity,we used a dissimilarity index(within and between elevational bands 100 m wide).The effect of a set of environmental and human disturbance variables on tree diversity and community composition was analyzed with general linear models and multivariate analyses,respectively.We registered 2,949 individual trees belonging to 176 species and 58families.The average species richness and alpha diversity per plot were 13(standard deviation±6)and 9(±5),respectively.General tree richness and alpha diversity increased in the middle part(unimodal patterns)of the elevational gradient,but pioneer species richness decreased linearly with elevation.The variance explained by general linear models was greater in richness(32%)than in alpha diversity(25.3%).The most important predictor variables were temperature(elevational gradient),which explained the unimodal pattern(richness and alpha diversity increase at intermediate levels of temperature),and slope orientation,which explained the increase in richness and alpha diversity toward the geographic north.Only temperature had a significant effect on pioneer species diversity(22%).For community composition,all the predictor variables evaluated had a significant effect,but the most important were slope aspect and temperature.Assemblages were almost completely different in plots that were farther apart along the elevation gradient and had different slope aspects.Finally,the forests at lower elevations(1500–1900 m)were those that had the most human disturbance.Our study reveals the importance of considering a set of environmental variables related to climate,topography(e.g.,slope aspect),and human disturbance to understand variation in diversity and composition of a tree community on a tropical volcano.With this information,we believe that it is important to implement conservation and restoration measures in the forests of the lower parts of the Tacanávolcano,complemented by studies that contribute to designing better conservation strategies.

Changes in cellular proliferation and plasma products are associated with liver failure

AIM To study the differences in immune response and cytokine profile between acute liver failure and selflimited acute hepatitis.METHODS Forty-six patients with self-limited acute hepatitis(AH), sixteen patients with acute liver failure(ALF), and twenty-two healthy subjects were involved in this study. The inflammatory and anti-inflammatory products in plasma samples were quantified using commercial enzyme-linked immunoassays and quantitative real-time PCR. The cellular immune responses were measured by proliferation assay using flow cytometry. The groups were divided into viral- and non-viral-induced selflimited AH and ALF. Thus, we worked with five groups: Hepatitis A virus(HAV)-induced self-limited acute hepatitis(HAV-AH), HAV-induced ALF(HAV-ALF), nonviral-induced self-limited acute hepatitis(non-viral AH), non-viral-induced acute liver failure(non-viral ALF), and healthy subjects(HC). Comparisons among HAV and non-viral-induced AH and ALF were performed.RESULTS The levels of mitochondrial DNA(mt DNA) and the cytokines investigated [interleukin(IL)-6, IL-8, IL-10, interferon gamma, and tumor necrosis factor] were significantly increased in ALF patients, independently of etiology(P < 0.05). High plasma mt DNA and IL-10 were the best markers associated with ALF [mt DNA: OR = 320.5(95%CI: 14.42-7123.33), P < 0.0001; and IL-10: OR = 18.8(95%CI: 1.38-257.94), P = 0.028] and death [mt DNA: OR = 12.1(95%CI: 2.57-57.07), P = 0.002; and IL-10: OR = 8.01(95%CI: 1.26-50.97), P = 0.027]. In the cellular proliferation assay, NK^(bright), NKT and regulatory T cells(TReg) predominated in virusspecific stimulation in HAV-induced ALF patients with an anergic behavior in the cellular response to mitotic stimulation. Therefore, in non-viral-induced ALF, anergic behavior of activated T cells was not observed after mitotic stimulation, as expected and as described by the literature. CONCLUSION mt DNA and IL-10 may be predictors of ALF and death. TReg cells are involved in immunological disturbance in HAV-induced ALF.

Comparative mitogenome phylogeography of two anteater genera (Tamandua and Myrmecophaga;Myrmecophagidae, Xenarthra): Evidence of discrepant evolutionary traits

The species within Xenarthra(sloths,anteaters,and armadillos)are quintessential South American mammals.Of the three groups,Vermilingua(anteaters)contains the fewest extant and paleontological species.Here,we sampled and sequenced the entire mitochondrial genomes(mitogenomes)of two Tamandua species(Tamandua tetradactyla and T.mexicana)(n=74)from Central and South America,as well as Myrmecophaga tridactyla(n=41)from South America.Within Tamandua,we detected three different haplogroups.The oldest(THI)contained many specimens with the T.tetradactyla morphotype(but also several with the T.mexicana morphotype)and originated in southeastern South America(currently Uruguay)before moving towards northern South America,where the THII haplogroup originated.THII primarily contained specimens with the T.mexicana morphotype(but also several with the T.tetradactyla morphotype)and was distributed in Central America,Colombia,and Ecuador.THI and THII yielded a genetic distance of 4%.THII originated in either northern South America or“in situ”in Central America with haplogroup THIII,which consisted of~50%T.mexicana and 50%T.tetradactyla phenotypes.THIII was mostly located in the same areas as THII,i.e.,Central America,Ecuador,and Colombia,though mainly in the latter.The three haplogroups overlapped in Colombia and Ecuador.Thus,T.tetradactyla and T.mexicana were not reciprocally monophyletic.For this reason,we considered that a unique species of Tamandua likely exists,i.e.,T.tetradactyla.In contrast to Tamandua,M.tridactyla did not show different morphotypes throughout its geographical range in the Neotropics.However,two very divergent genetic haplogroups(MHI and MHII),with a genetic distance of~10%,were detected.The basal haplogroup,MHI,originated in northwestern South America,whereas the more geographically derived haplogroup,MHII,overlapped with MHI,but also expanded into central and southern South America.Thus,Tamandua migrated from south to north whereas Myrmecophaga migrated from north to south.Our results also showed that temporal mitochondrial diversification for Tamandua began during the Late Pliocene and Upper Pleistocene,but for Myrmecophaga began during the Late Miocene.Furthermore,both taxa showed elevated levels of mitochondrial genetic diversity.Tamandua showed more evidence of female population expansion than Myrmecophaga.Tamandua experienced population expansion~0.6–0.17 million years ago(Mya),whereas Myrmecophaga showed possible population expansion~0.3–0.2 Mya.However,both taxa experienced a conspicuous female decline in the last 10000–20000 years.Our results also showed little spatial genetic structure for both taxa.However,several analyses revealed higher spatial structure in Tamandua than in Myrmecophaga.Therefore,Tamandua and Myrmecophaga were not subjected to the same biogeographical,geological,or climatological events in shaping their genetic structures.

巴西濒危景观“铁四角”地区铁矿石露头对植物多样性的影响

在位于植物多样性中心地带的全球矿藏最丰富的地区，由于生态系统的作用迄今为止仍被忽视，生物多样性和生态系统脆弱性超出了本文图片中的程度。

Elaphoglossum(Dryopteridaceae-Fern)of Amazon Rainforest in Brazil:Anatomic Characterization and Adaptative Strategies

This study describes the anatomy of sterile leaves of Elaphoglossum discolor (Kuhn) C. Chr., E. flaccidum (Fée) T. Moore and E. laminarioides (Bory ex Fée) T. Moore, the most representative species of the genus in the Ecological Park of Gunma in Pará State. It reports the main diagnostic characters and provides new systematic data for the group. In addition, it locates the production and accumulation sites of bioactive compounds to determine possible adaptive strategies of these species in the Amazon rainforest environment. Diagnostic structural features include stoma typology, central veins and margin forms, type of mesophyll, and the presence of schlerenchymatous sheaths in the cortex, among others. Among the bioactive compounds related to defense adaptation are phenolic compounds, which occur in all three species, and alkaloids and mucilage, which are exclusive to E. laminarioides. Of the three species studied, E. laminarioides has features that make it the best suited to the rainforest environment.

Ecophysiological basis of the Jack-and-Master strategy:Taraxacum officinale(dandelion)as an example of a successful invader

Aims Successful invasive plants are often assumed to display significant levels of phenotypic plasticity.Three possible strategies by which phenotypic plasticity may allow invasive plant species to thrive in changing environments have been suggested:(i)via plasticity in morphological or physiological traits,invasive plants are able to maintain a higher fitness than native plants in a range of environ-ments,including stressful or low-resource habitats:a‘Jack-of-all-trades’strategy;(ii)phenotypic plasticity allows the invader to better exploit resources available in low stress or favorable habitats,show-ing higher fitness than native ones:a‘Master-of-some’strategy and(iii)a combination of these abilities,the‘Jack-and-Master’strategy.Methods We evaluated these strategies in the successful invader Taraxacum officinale in a controlled experiment mimicking natural environmen-tal gradients.We set up three environmental gradients consisting of factorial arrays of two levels of temperature/light,temperature/water and light/water,respectively.We compared several ecophysiologi-cal traits,as well as the reaction norm in fitness-related traits,in both T.officinale and the closely related native Hypochaeris thrin-cioides subjected to these environmental scenarios.Important Findings Overall,T.officinale showed significantly greater accumulation of biomass and higher survival than the native H.thrincioides,with this difference being more pronounced toward both ends of each gradient.T.officinale also showed significantly higher plasticity than its native counterpart in several ecophysiological traits.Therefore,T.officinale exhibits a Jack-and-Master strategy as it is able to main-tain higher biomass and survival in unfavorable conditions,as well as to increase fitness when conditions are favorable.We suggest that this strategy is partly based on ecophysiological responses to the environment,and that it may contribute to explaining the successful invasion of T.officinale across different habitats.

Positive interactions by cushion plants in high mountains:fact or artifact?

Positive interactions are defined as non-trophic interactions where at least one of the interacting species is benefited in terms of fitness and the other remains unaffected.Nevertheless,the bidirectional feedbacks between species may be positive,neutral or negative.Thus,if facilitated species induce negative effects on their‘nurses’,the assumed definition of positive interactions could be reconsidered.Methods We assessed if ecological interactions between cushions of Azorella madreporica and their facilitated species are positive.Specifically,we tested if cover of facilitated species has any costs for cushion plants from an ecophysiological perspective,and if these costs increase with the amount of cover of facilitated species.In addition,through pathway analysis and correlations,we assessed if cover and richness of facilitated species have a direct and/or indirect effect on the fitness of cushion plants.Important Findings We found that facilitated plant species induced a significant cost for their nurses(cushion plants),and this cost increases with cover of the facilitated species.Additionally,the facilitated species exert a strong direct negative effect on the cushion’s fitness and a moderate indirect negative cost evident through the nutrient status and physiological performance of cushion plants.We thus contribute evidence that positive interactions between high mountain cushion plants of central Chile and their‘facilitated’species may be an artifact more than a fact,especially when bidirectional effects are considered;contrasting with the majority of studies that document only one side of the interaction.

Worker laying in leafcutter ant Acromyrmex subterraneus brunneus （Formicidae, Attini）

We studied the process of offspring production in queenless colonies of Acromyrmex subterraneus brunneus, and particularly evaluated the ovary development of workers as a function of their age. For this, subcolonies were set up and evaluated at different periods of isolation from the queen （2, 4 and 6 months）, besides individually labeled age groups. The subcolonies were assessed according to offspring production and ovaries containing oocytes or not. The evaluations showed worker oviposition and development of males originating from worker-laid eggs. At 2 months＇ absence of the queen, eggs and larvae were found, with eggs in a higher proportion than larvae. After 4 months, the proportion of eggs had reduced while larvae had increased, and a pupa was found in one subcolony. At 6 months, besides a higher share of larvae, one pupa and one adult male were found. Dissection of workers revealed ovaries containing oocytes during the periods of evaluation. Only a group of medium-sized and large workers, 23.3%, 20.9% and 37.5% of the population from each period assessed in queenless subcolonies respectively, presented developed oocytes in the ovary. The same was observed in colonies with a queen, with 17.6%, 19.6% and 7.8% of the group of dissected workers from each time period, respectively. With respect to worker age, we observed by dissection of the ovary, that the greatest percentage of individuals with ovarioles containing oocytes occurred at 45 days （6 weeks） up to 90 days （12 weeks）. These results probably are associated with the workers reproduction and the laying of trophic and reproductive eggs in colonies with and without a queen; these eggs have distinct functions in each situation.