Existence of long-lasting experience-dependent plasticity in endocrine cell networks

Experience-dependent plasticity of cell and tissue function is critical for survival by allowing organisms to dynamically adjust physiological processes in response to changing or harsh environmental conditions. Despite the conferred evolutionary advantage, it remains unknown whether emergent experience-dependent properties are present in cell populations organized as networks within endocrine tissues involved in regulating body-wide homeostasis. Here we show, using lactation to repeatedly activate a specific endocrine cell network in situ in the mammalian pituitary, that templates of prior demand are permanently stored through stimulus-evoked alterations to the extent and strength of cell–cell connectivity. Strikingly, following repeat stimulation, evolved population behaviour leads to improved tissue output. As such, long-lasting experience-dependent plasticity is an important feature of endocrine cell networks and underlies functional adaptation of hormone release

Depletion of stromal cells expressing fibroblast activation protein-α from skeletal muscle and bone marrow results in cachexia and anemia.

Fibroblast activation protein-α (FAP) identifies stromal cells of mesenchymal origin in human cancers and chronic inflammatory lesions. In mouse models of cancer, they have been shown to be immune suppressive, but studies of their occurrence and function in normal tissues have been limited. With a transgenic mouse line permitting the bioluminescent imaging of FAP(+) cells, we find that they reside in most tissues of the adult mouse. FAP(+) cells from three sites, skeletal muscle, adipose tissue, and pancreas, have highly similar transcriptomes, suggesting a shared lineage. FAP(+) cells of skeletal muscle are the major local source of follistatin, and in bone marrow they express Cxcl12 and KitL. Experimental ablation of these cells causes loss of muscle mass and a reduction of B-lymphopoiesis and erythropoiesis, revealing their essential functions in maintaining normal muscle mass and hematopoiesis, respectively. Remarkably, these cells are altered at these sites in transplantable and spontaneous mouse models of cancer-induced cachexia and anemia. Thus, the FAP(+) stromal cell may have roles in two adverse consequences of cancer: their acquisition by tumors may cause failure of immunosurveillance, and their alteration in normal tissues contributes to the paraneoplastic syndromes of cachexia and anemia

Clinical spectrum of MTOR-related hypomelanosis of Ito with neurodevelopmental abnormalities.

PURPOSE: Hypomelanosis of Ito (HI) is a skin marker of somatic mosaicism. Mosaic MTOR pathogenic variants have been reported in HI with brain overgrowth. We sought to delineate further the pigmentary skin phenotype and clinical spectrum of neurodevelopmental manifestations of MTOR-related HI. METHODS: From two cohorts totaling 71 patients with pigmentary mosaicism, we identified 14 patients with Blaschko-linear and one with flag-like pigmentation abnormalities, psychomotor impairment or seizures, and a postzygotic MTOR variant in skin. Patient records, including brain magnetic resonance image (MRI) were reviewed. Immunostaining (n = 3) for melanocyte markers and ultrastructural studies (n = 2) were performed on skin biopsies. RESULTS: MTOR variants were present in skin, but absent from blood in half of cases. In a patient (p.[Glu2419Lys] variant), phosphorylation of p70S6K was constitutively increased. In hypopigmented skin of two patients, we found a decrease in stage 4 melanosomes in melanocytes and keratinocytes. Most patients (80%) had macrocephaly or (hemi)megalencephaly on MRI. CONCLUSION: MTOR-related HI is a recognizable neurocutaneous phenotype of patterned dyspigmentation, epilepsy, intellectual deficiency, and brain overgrowth, and a distinct subtype of hypomelanosis related to somatic mosaicism. Hypopigmentation may be due to a defect in melanogenesis, through mTORC1 activation, similar to hypochromic patches in tuberous sclerosis complex

Interceptions et introductions en France de Longicornes asiatiques : cas des Anoplophora glabripennis (Motschulsky) et chinensis (Forster) (Coleoptera Cerambycidae)

Les interceptions et introductions en France de Coléoptères Cerambycidae se multiplient depuis quelques années. Deux espèces du genre asiatique Anoplophora ont été trouvées récemment dans l'Ain, l'Ardèche, l'Isère, le Loiret et la Marne. A. chinensis a été systématiquement importé avec des bonsaïs mais un seul foyer a été détecté pour l'instant. A. glabripennis a fait l'objet d'une introduction à Gien (Loiret) dont l'éradication est tentée. La présence en France d'A. glabripennis et A. chinensis était soupçonnée suite à leurs introductions en Autriche et en Italie. Il s'agit d'organismes de quarantaine soumis à une législation rigoureuse car ils sont de redoutables ravageurs des arbres et arbustes sains dans leurs pays d'origine. Leur implantation durable dans notre faune n'est pas certaine pour l'instant mais les incertitudes du résultat des éradications en cours et l'éventualité de foyers oubliés rendent probable leur présence irréversible à court terme. Le genre Anoplophora compte 36 espèces dont certaines peuvent être confondues avec glabripennis et chinensis, elles mêmes difficiles à distinguer sans examen minutieux. Au moins deux autres espèces de ce genre sont susceptibles d'être également importées en France et de s'y acclimater.Cocquempot Christian, Carmignac David, Prost Monique. Interceptions et introductions en France de Longicornes asiatiques : cas des Anoplophora glabripennis (Motschulsky) et chinensis (Forster) (Coleoptera Cerambycidae). In: Bulletin mensuel de la Société linnéenne de Lyon, 72ᵉ année, n°8, octobre 2003. pp. 273-278

Steroid regulation of growth hormone (GH) receptor and GH-binding protein messenger ribonucleic acids in the rat

In the rat, the GH receptor (GHR) and the GH-binding protein (GHBP), which arise from alternative splicing of the same gene, show a sexually dimorphic and GH-dependent expression pattern. Multiple alternative 5\u27-untranslated regions (UTRs) are present in GHR and GHBP transcripts in the rat, one of which, GHR1, has recently been shown to be liver specific and found at higher levels in females. We have measured the hepatic GHR1, GHR, and GHBP transcript levels, by RNase protection and solution hybridization assay, in animals with differing hormonal status, in which hepatic GHR binding and plasma GHBP have been previously assayed. Estradiol (E2) induced GHR1 in males, whereas ovariectomy or the antiestrogen tamoxifen reduced GHR1 expression in females. The induction of GHR1 by E2 was GH dependent, being lower in GH-deficient dwarf rats and absent in hypophysectomized rats, paralleling previous measurements of plasma GHBP and hepatic GHR binding in these animals. Significant changes in GHR1 could explain the trends seen in the same extracts when coding region probes were used. Short-term adrenalectomy had no effect on GHR and GHBP expression, but dexamethasone markedly reduced both protein and messenger RNA (mRNA) levels. Corticosterone treatment had no effect alone but reduced the E2-induced increase in GHR1 levels, whereas methylprednisolone administered orally reduced hepatic GH binding, plasma GHBP, and GHR1 mRNA levels. Thus, 5\u27-UTRs, encoded by different first exons, are involved in the regulation of hepatic GHR and GHBP expression and need to be considered when comparing effects of hormonal manipulation on the mRNA transcripts and protein products of the GHR gene. Previous studies have found discrepancies between levels of protein expression and mRNA transcripts measured only with coding region probes. Our results suggest that posttranscriptional differences related to 5\u27-UTR heterogeneity in the GHR gene explain some of these discrepancie

Effects of microcystin-producing and microcystin-free strains of

The effects of cyanobacterial toxins on herbivorous zooplankton depend on cyanobacterial strains, zooplankton species and environmental conditions. To explore the relationship between zooplankton and cyanobacteria, we investigated the effects of Planktothrix agardhii extracts on Daphnia magna population dynamics. We designed an experiment where individuals were grown in the presence of extracts of two P. agardhii strains. We monitored daily life-history parameters of D. magna individuals subjected to microcystin-RR (MC-RR), intracellular and extracellular extracts of a microcystin-producing strain (MC-strain, PMC 75.02) and a microcystin-free strain (MC-free strain, PMC 87.02) of P. agardhii. Measured life-history parameters of D. magna were used to build population dynamics models and compute expected population growth rate, replacement rate, generation time and proportion of adult and juveniles at demographic equilibrium. Results show that MC-RR tends to slow the life history (reduced growth rate and larger proportion of adults). In contrast, intracellular extracts of the two strains tend to accelerate the life history (increased growth rate, decreased generation time and lower proportion of adults). Extracellular extracts produce the same trends as the intracellular extracts but to a lesser extent. However, the MC-strain has stronger effects than the MC-free strain. Interestingly, extracellular extracts of the MC-free strain may have effects comparable to pure MC-RR. Moreover, in the presence of MC-RR and both cyanobacterial extracts, the daily fecundities present a cyclic pattern. These results suggest that MC-RR and unknown metabolites of cyanobacterial extracts have negative effects on D. magna reproduction processes such as those observed with endocrine-disruptive molecules

Unidirectional response to bidirectional selection on body size II. Quantitative genetics

International audienceAnticipating the genetic and phenotypic changes induced by natural or artificial selection requires reliable estimates of trait evolvabilities (genetic variances and covariances). However, whether or not multivariate quantitative genetics models are able to predict precisely the evolution of traits of interest, especially fitness‐related, life history traits, remains an open empirical question. Here, we assessed to what extent the response to bivariate artificial selection on both body size and maturity in the medaka Oryzias latipes, a model fish species, fits the theoretical predictions. Three lines (Large, Small, and Control lines) were differentially selected for body length at 75 days of age, conditional on maturity. As maturity and body size were phenotypically correlated, this selection procedure generated a bi‐dimensional selection pattern on two life history traits. After removal of nonheritable trends and noise with a random effect (“animal”) model, the observed selection response did not match the expected bidirectional response. For body size, Large and Control lines responded along selection gradients (larger body size and stasis, respectively), but, surprisingly, the Small did not evolve a smaller body length and remained identical to the Control line throughout the experiment. The magnitude of the empirical response was smaller than the theoretical prediction in both selected directions. For maturity, the response was opposite to the expectation (the Large line evolved late maturity compared to the Control line, while the Small line evolved early maturity, while the opposite pattern was predicted due to the strong positive genetic correlation between both traits). The mismatch between predicted and observed response was substantial and could not be explained by usual sources of uncertainties (including sampling effects, genetic drift, and error in G matrix estimates)

Bottom-up effects of lake sediment on pelagic food-web compartments: a mesocosm study

Sediment plays a key role in organic matter (OM) and internal nutrient cycling in lakes. The role of sediment as a source of OM and its potential bottom-up effects on the pelagic food web have rarely been studied. Particularly, the influence of the biochemical composition of sediment OM on pelagic compartments remains largely unknown. During a 5-month experiment, we studied the influence of two different sediments added at the bottom of large replicated mesocosms on the biomass of seston and zooplankton, and their elemental and lipid compositions. The influence of sediment treatments on sedimentation rates, elemental and biochemical compositions and potential biodegradability of recently sedimented OM (c. 1 week) was also examined. The two added sediments (S1 and S2) presented contrasting elemental and biochemical compositions and potential biodegradabilities. According to their contents of organic carbon, nitrogen, proteins, sugars and polyunsaturated fatty acids, S2 appeared to be much more biodegradable than S1. Therefore, the S2 sediment was expected to release more nutrients and OM to the water column than S1, leading to changes in communities, stoichiometry and lipid compositions of pelagic compartments. Probably due to its very poor content of labile compounds, the presence of S1 at the bottom of the mesocosms did not induce changes in the biomass of seston and zooplankton. Only few changes in the stoichiometry of these compartments were observed. In contrast, S2 sediment released more phosphorus and dissolved OM into the water column than S1. As a result, the S2 treatment induced an increase in seston biomass and therefore in zooplankton biomass via herbivory. None of the sediment treatments affected the lipid composition of seston and zooplankton. Moreover, neither S1 nor S2 induced changes in the sedimentation rates, elemental and lipid compositions, and potential biodegradability of recent sediments. Our mesocosm experiment suggests that differences in the quality of lake sediments lead to moderate changes in the pelagic communities in the absence of planktivorous or omnivorous fish. Our results could partly explain the efficiency of biomanipulation for improving water quality of eutrophic lakes despite potential nutrient release from sediment

Effect of habitat spatiotemporal structure on collembolan diversity

International audienceLandscape fragmentation is a major threat to biodiversity. It results in the transformation of continuous (hence large) habitat patches into isolated (hence smaller) patches, embedded in a matrix of another habitat type. Many populations are harmed by fragmentation because remnant patches do not fulfil their ecological and demographic requirements. In turn, this leads to a loss of biodiversity, especially if species have poor dispersal abilities. Moreover, landscape fragmentation is a dynamic process in which patches can be converted from one type of habitat to another. A recently created habitat might suffer from a reduced biodiversity because of the absence of adapted species that need a certain amount of time to colonize the new patch (e.g. direct meta-population effect). Thus landscape dynamics lead to complex habitat spatiotemporal structured, in which each patch is more or less continuous in space and time. In this study, we define habitat spatial structure as the degree to which a habitat is isolated from another habitat of the same kind and temporal structure as the time since the habitat is in place. Patches can also display reduced biodiversity because their spatial or temporal structures are correlated with habitat quality (e.g. indirect effects). We discriminated direct meta-community effects from indirect (habitat quality) effects of the spatiotemporal structure of habitats on biodiversity using Collembola as a model. We tested the relative importance of spatial and temporal structure of habitats for collembolan diversity, taking soil properties into account. In an agroforested landscape, we set up a sampling design comprised of two types of habitats (agriculture versus forest), a gradient of habitat isolation (three isolation classes) and two contrasting ages of habitats. Our results showed that habitat temporal structure is a key factor shaping collembolan diversity. A reduced diversity was detected in recent habitats, especially in forests. Interactions between temporal continuity and habitat quality were also detected by taking into account soil properties: diversity increased with soil carbon content, especially in old forests. Negative effects of habitat age on diversity were stronger in isolated patches. We conclude that habitat temporal structure is a key factor shaping collembolan diversity, while direction and amplitude of its effect depend on land use type and spatial isolation