Altered chemokine production and accumulation of regulatory T cells in intestinal adenomas of APCMin/+ mice

Tumor progression in the colon moves from aberrant crypt foci to adenomatous polyps to invasive carcinomas. The composition of the tumor-infiltrating leukocyte population affects the ability of the immune system to fight the tumor. T cell infiltration into colorectal adenocarcinomas, particularly T helper 1 (Th1) type T cells as well as increased regulatory T cell (Treg) frequencies, is correlated with improved prognosis. However, whether Th1 cells and Tregs are already present at the adenoma stage is not known. In this study, the APC^Min/+ mouse model of intestinal adenomatous polyposis was used to investigate tumor-associated lymphocyte subsets and the mechanisms of their accumulation into gastrointestinal adenomas. Compared to unaffected tissue, adenomas accumulated CD4⁺FoxP3⁺ putative Treg in parallel with lower frequencies of conventional T cells and B cells. The accumulation of Treg was also observed in human adenomatous polyps. Despite high Treg numbers, the function of conventional T cells present in the APC^Min/+ adenomas was not different from those in the unaffected tissue. Adenomas displayed an altered chemokine balance, with higher CCL17 and lower CXCL11 and CCL25 expression than in the unaffected tissue. In parallel, CXCR3⁺ Tregs were largely absent from adenomas. The data indicate that already in early stages of tumor development, the balance of lymphocyte-recruiting chemokines is altered possibly contributing to the observed shift toward higher frequencies of Treg.     

Phenology of the red mangrove, Rhizophora mangle L., in the Caeté Estuary,Pará, equatorial Brazil

The current study presents phenology data for Rhizophora mangle from two equatorial mangrove stands with different salinity regimes in Brazil. Observations based on litter fall and individual shoot development were compared and related to environmental factors. Patterns observed in litter fall were consistent with results of direct monitoring. While both reproductive organs and leaves were produced throughout the year, rates of formation followed seasonal trends. Distinct differences in propagule production between low and high salinity sites and between years of observation were detected; main propagule release was, however, restricted to the wet season which offers enhanced conditions for propagule establishment. Emergence of flowers was linked to leaf production. While there was no obvious single peak in leaf production, it was reduced towards the end of the dry season at both high and low salinity sites. Time series analysis revealed an independent pattern of leaf development superimposed on this annual seasonal trend, indicating slower development of leaf primordia during periods of low light availability in the wet season. No significant difference in age structure was detected between sun and shade leaves; maximum leaf life-time was approximately 1 year.     

Certain aspects of resistance of plum trees to bacterial canker: Part III. The action of cell-free filtrates of Pseudomonas mors-prunorum Wormald and related phyto-pathogenic bacteria on plum trees

A technique for introducing 2-3 c.c. liquid into the bark of plum trees is described. Parallel injections with dyestuff throughout the spring failed to afford a reliable index of the invasive powers of the various test fluids introduced in this manner.
A susceptible variety of plum (Giant Prune) showed greater injury by cell-free filtrates of Ps. morsprunorum than did a resistant variety (Warwickshire Drooper), which showed negligible injury. The greatest injuries were caused by filtrates of cultures 5 weeks old, and over, especially when concentrated.
Of other bacteria tested Ps. prunicola, Ps. syringae strains, Syringa 3, Ap. No. 1, Ap. No. 2, and Bact. pruni , yielded damaging filtrates, whereas Ps. syringae , strains pear 6 and 7, Ps. tabaci, Ps. fluorescens, Ps. marginalis, Ps. phaseolicola, Ps. tumefaciens, Ps. pisi and Ps. cerasi failed to do so.
Some evidence is advanced for the view that the deleterious activity of Ps. mors-prunorum may be due in part to an endotoxin of protein nature obtainable from the dried bacterial cells by acetic acid extraction.     

Implications for molecular mechanisms of glycoprotein hormone receptors using a new sequence-structure-function analysis resource

Comparison between wild-type and mutated glycoprotein hormone receptors (GPHRs), TSH receptor, FSH receptor, and LH-chorionic gonadotropin receptor is established to identify determinants involved in molecular activation mechanism. The basic aims of the current work are 1) the discrimination of receptor phenotypes according to the differences between activity states they represent, 2) the assignment of classified phenotypes to three-dimensional structural positions to reveal 3) functional-structural hot spots and 4) interrelations between determinants that are responsible for corresponding activity states. Because it is hard to survey the vast amount of pathogenic and site-directed mutations at GPHRs and to improve an almost isolated consideration of individual point mutations, we present a system for systematic and diversified sequence-structure-function analysis (http://www.fmp-berlin.de/ssfa). To combine all mutagenesis data into one set, we converted the functional data into unified scaled values. This at least enables their comparison in a rough classification manner. In this study we describe the compiled data set and a wide spectrum of functions for user-driven searches and classification of receptor functionalities such as cell surface expression, maximum of hormone binding capability, and basal as well as hormone-induced Galphas/Galphaq mediated cAMP/inositol phosphate accumulation. Complementary to known databases, our data set and bioinformatics tools allow functional and biochemical specificities to be linked with spatial features to reveal concealed structure-function relationships by a semiquantitative analysis. A comprehensive discrimination of specificities of pathogenic mutations and in vitro mutant phenotypes and their relation to signaling mechanisms of GPHRs demonstrates the utility of sequence-structure-function analysis. Moreover, new interrelations of determinants important for selective G protein-mediated activation of GPHRs are resumed.     

Cytokines promote Wnt signaling and inflammation and impair the normal differentiation and lipid accumulation in 3T3-L1 preadipocytes

Obesity with enlarged fat cells is associated with high local concentrations of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFalpha) in the adipose tissue. We examined the effects of this inflammatory state on 3T3-L1 preadipocyte development and differentiation to mature adipose cells. Both IL-6 and TNFalpha impaired the normal differentiation pattern and lipid accumulation. However, IL-6 allowed a normal early induction of differentiation with inhibition of Wnt10b and Pref-1, whereas expression of CCAAT/enhancer-binding protein alpha, in contrast to peroxisome proliferator-activated receptor gamma, was markedly reduced. TNFalpha also allowed a normal early induction of differentiation, whereas the terminal differentiation to adipose cells was completely prevented. However, both cytokines induced an inflammatory phenotype of the cells but with different profiles. Remarkably, both IL-6 and TNFalpha maintained and augmented the canonical Wnt signaling associated with low axin and high low density lipoprotein receptor-related protein (LRD), Dishevelled, and beta-catenin levels. TNFalpha, but not IL-6, activated Wnt10b expression, whereas IL-6 increased the apparent phosphorylation of Dishevelled. Thus, both IL-6 and TNFalpha prevent the normal development of preadipocytes to fully differentiated adipose cells and, instead, promote an inflammatory phenotype of the adipocytes. These results provide an explanation as to why obesity and diabetes are associated with both local and systemic inflammation, insulin resistance, and ectopic lipid accumulation.     

Chemoattraction of macrophages, T lymphocytes, and mast cells is evolutionarily conserved within the human alpha-defensin family

Human defensins are natural peptide antibiotics. On the basis of the position and bonding of six conserved cysteine residues, they are divided into two families, designated alpha- and beta-defensins. Human alpha-defensins are expressed predominantly in neutrophils (human neutrophil peptides (HNP) 1-4) or intestinal Paneth cells (human defensins (HD) 5 and 6). Although alpha-defensins have been implicated in the pathogenesis of inflammatory bowel disease, their immunomodulatory functions are poorly understood. In the present study, HNP-1, HNP-3, and HD5 were found to be potent chemotaxins for macrophages but not dendritic cells using Galphai proteins and MAPK as signal transducers. Alpha-defensins were also chemoattractive for the human mast cell line HMC-1 but lacked, in contrast to beta-defensins, the ability to induce intracellular calcium fluxes. Furthermore, HNP-1, HNP-3, and HD5 comparably mobilized naive as well as memory T lymphocytes. Using the protein kinase C (PKC) inhibitors GF109 and G?6976, we observed a PKC-independent functional desensitization to occur between human alpha-defensins, which suggests a common receptor for HNP-1, HNP-3, and HD5 on immune cells. This alpha-defensin receptor was subject to heterologous desensitization by the PKC activator PMA and to PKC-dependent cross-desensitization by human beta-defensins. Conversely, alpha-defensins desensitized beta-defensin-mediated migration of immune cells in a PKC-dependent manner, suggesting unique receptors for both defensin families. Taken together, our observations indicate that chemoattraction of macrophages, T lymphocytes, and mast cells represents an immunomodulatory function which is evolutionarily conserved within the human alpha-defensin family and tightly regulated by beta-defensins.     

Availability of water affects renewal of tissues in migratory blackcaps during stopover

Migrating blackcaps (Sylvia atricapilla) were used to test the predictions that (1) the rebuilding of the digestive tract, as reflected by mass-specific consumption of food on the first 2-3 days of a stopover, is faster in birds with access to drinking water than in birds without, and (2) that adipose tissue and pectoral muscles grow faster and to a greater extent in birds with unlimited access to water. We simulated migratory stopover in two experiments. In Experiment I, each of 31 birds was randomly assigned to one of three experimental groups for 6 days. Along with mealworms (～64% water) ad libitum, Group 1 received drinking water ad libitum; Group 2 had 0.5 h/day access to water; and Group 3 had no access to water. In Experiment II, 30 birds were offered a mixed diet for insectivorous birds (～33% water) ad libitum for 6 days, while randomly assigned to two groups: (1) Water ad libitum-control; and (2) 30 min access to water twice a day. We measured lean mass and fat mass using dual energy X-ray absorptiometry, as well as body mass (m(b)), pectoral muscle index (PMI), and daily intake of food and water. Mean daily water intake was significantly different among the groups in both experiments. However, the availability of drinking water positively affected the rates of gain of lean and fat mass only in birds fed with the mixed, relatively dry diet. Furthermore, mass-specific daily food intake was affected by the availability of drinking water only in the mixed diet experiment, in which birds with unlimited access to drinking water reached an asymptote, 1 day earlier than birds in the water-restricted group. We suggest that in birds consuming diets with low water content, the lack of sufficient drinking water may result in slower rebuilding of the digestive tract, or may influence biochemical processes in the gut that result in slower growth of tissue. Although blackcaps obtained sufficient water from preformed and metabolic water to renew lost tissues when eating mealworms, given access to water, the birds drank prodigiously. Our results also suggest that if drinking water is unavailable to migrating blackcaps, their choices are restricted to water-rich foods, which may constrain their rate of feeding and thus the rate at which they deposit fat. Consequently, drinking water may have an important influence on birds' migratory strategies with respect to habitat selection, use of energy, and the saving of time.     

Seasonal locomotion and home-range characteristics of European hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) in an arable region in central Germany

We studied seasonal use of space by 38 radio-tracked European hares in an arable region in central Germany over 5 years. Mean distance between successive daytime and nighttime fixes of a hare amounted to 226 m, and an average distance of 172 m was recorded for successive daytime fixes. The hares shifted the centres of their home ranges from one 2-month period to the next by an average distance of 131 m and over a time span of 11.2 months by 216 m. The size of their 2-month home ranges (MCP 95) averaged 21 ha; the variation between individuals was high. Night ranges were larger than day ranges. Mean size of seasonal home ranges—based on daytime and nighttime fixes—remained largely constant throughout the year. Home-range size increased as the day-to-night distance increased, as the number of used habitat elements increased and as frequency of use of inner field parts during the daytime increased. Home-range size was inversely related to population density. On average, 32% of the area of the home range of a hare overlapped with the home range of a neighbouring conspecific. When related to the population density of adult hares in spring, the home range of a single hare was estimated to overlap with 13–21 home ranges of adults as well as an indefinite number of juveniles. The large intraseasonal variation in locomotion and home-range characteristics is interpreted in relationship to the social structure of European hares.     

The Function of the Chemokine Receptor CXCR6 in the T Cell Response of Mice against Listeria monocytogenes

The chemokine receptor CXCR6 is expressed on different T cell subsets and up-regulated following T cell activation. CXCR6 has been implicated in the localization of cells to the liver due to the constitutive expression of its ligand CXCL16 on liver sinusoidal endothelial cells. Here, we analyzed the role of CXCR6 in CD8⁺ T cell responses to infection of mice with Listeria monocytogenes. CD8⁺ T cells responding to listerial antigens acquired high expression levels of CXCR6. However, deficiency of mice in CXCR6 did not impair control of the L. monocytogenes infection. CXCR6-deficient mice were able to generate listeria-specific CD4⁺ and CD8⁺ T cell responses and showed accumulation of T cells in the infected liver. In transfer assays, we detected reduced accumulation of listeria-specific CXCR6-deficient CD8⁺ T cells in the liver at early time points post infection. Though, CXCR6 was dispensable at later time points of the CD8⁺ T cell response. When transferred CD8⁺ T cells were followed for extended time periods, we observed a decline in CXCR6-deficient CD8⁺ T cells. The manifestation of this cell loss depended on the tissue analyzed. In conclusion, our results demonstrate that CXCR6 is not required for the formation of a T cell response to L. monocytogenes and for the accumulation of T cells in the infected liver but CXCR6 appears to influence long-term survival and tissue distribution of activated cells.