Mechanistic evidence for tracking the seasonality of photosynthesis with solar-induced fluorescence.

Northern hemisphere evergreen forests assimilate a significant fraction of global atmospheric CO2 but monitoring large-scale changes in gross primary production (GPP) in these systems is challenging. Recent advances in remote sensing allow the detection of solar-induced chlorophyll fluorescence (SIF) emission from vegetation, which has been empirically linked to GPP at large spatial scales. This is particularly important in evergreen forests, where traditional remote-sensing techniques and terrestrial biosphere models fail to reproduce the seasonality of GPP. Here, we examined the mechanistic relationship between SIF retrieved from a canopy spectrometer system and GPP at a winter-dormant conifer forest, which has little seasonal variation in canopy structure, needle chlorophyll content, and absorbed light. Both SIF and GPP track each other in a consistent, dynamic fashion in response to environmental conditions. SIF and GPP are well correlated (R2 = 0.62-0.92) with an invariant slope over hourly to weekly timescales. Large seasonal variations in SIF yield capture changes in photoprotective pigments and photosystem II operating efficiency associated with winter acclimation, highlighting its unique ability to precisely track the seasonality of photosynthesis. Our results underscore the potential of new satellite-based SIF products (TROPOMI, OCO-2) as proxies for the timing and magnitude of GPP in evergreen forests at an unprecedented spatiotemporal resolution.

A genetically defined asymmetry underlies the inhibitory control of flexor-extensor locomotor movements.

V1 and V2b interneurons (INs) are essential for the production of an alternating flexor-extensor motor output. Using a tripartite genetic system to selectively ablate either V1 or V2b INs in the caudal spinal cord and assess their specific functions in awake behaving animals, we find that V1 and V2b INs function in an opposing manner to control flexor-extensor-driven movements. Ablation of V1 INs results in limb hyperflexion, suggesting that V1 IN-derived inhibition is needed for proper extension movements of the limb. The loss of V2b INs results in hindlimb hyperextension and a delay in the transition from stance phase to swing phase, demonstrating V2b INs are required for the timely initiation and execution of limb flexion movements. Our findings also reveal a bias in the innervation of flexor- and extensor-related motor neurons by V1 and V2b INs that likely contributes to their differential actions on flexion-extension movements.

Identification of a spinal circuit for light touch and fine motor control.

Sensory circuits in the dorsal spinal cord integrate and transmit multiple cutaneous sensory modalities including the sense of light touch. Here, we identify a population of excitatory interneurons (INs) in the dorsal horn that are important for transmitting innocuous light touch sensation. These neurons express the ROR alpha (RORα) nuclear orphan receptor and are selectively innervated by cutaneous low threshold mechanoreceptors (LTMs). Targeted removal of RORα INs in the dorsal spinal cord leads to a marked reduction in behavioral responsiveness to light touch without affecting responses to noxious and itch stimuli. RORα IN-deficient mice also display a selective deficit in corrective foot movements. This phenotype, together with our demonstration that the RORα INs are innervated by corticospinal and vestibulospinal projection neurons, argues that the RORα INs direct corrective reflex movements by integrating touch information with descending motor commands from the cortex and cerebellum.

Shp2/MAPK signaling controls goblet/paneth cell fate decisions in the intestine.

In the development of the mammalian intestine, Notch and Wnt/ß-catenin signals control stem cell maintenance and their differentiation into absorptive and secretory cells. Mechanisms that regulate differentiation of progenitors into the three secretory lineages, goblet, paneth, or enteroendocrine cells, are not fully understood. Using conditional mutagenesis in mice, we observed that Shp2-mediated MAPK signaling determines the choice between paneth and goblet cell fates and also affects stem cells, which express the leucine-rich repeat-containing receptor 5 (Lgr5). Ablation of the tyrosine phosphatase Shp2 in the intestinal epithelium reduced MAPK signaling and led to a reduction of goblet cells while promoting paneth cell development. Conversely, conditional mitogen-activated protein kinase kinase 1 (Mek1) activation rescued the Shp2 phenotype, promoted goblet cell and inhibited paneth cell generation. The Shp2 mutation also expanded Lgr5+ stem cell niches, which could be restricted by activated Mek1 signaling. Changes of Lgr5+ stem cell quantities were accompanied by alterations of paneth cells, indicating that Shp2/MAPK signaling might affect stem cell niches directly or via paneth cells. Remarkably, inhibition of MAPK signaling in intestinal organoids and cultured cells changed the relative abundance of Tcf4 isoforms and by this, promoted Wnt/ß-catenin activity. The data thus show that Shp2-mediated MAPK signaling controls the choice between goblet and paneth cell fates by regulating Wnt/ß-catenin activity.

A transcription factor code defines nine sensory interneuron subtypes in the mechanosensory area of the spinal cord.

Interneurons in the dorsal spinal cord process and relay innocuous and nociceptive somatosensory information from cutaneous receptors that sense touch, temperature and pain. These neurons display a well-defined organization with respect to their afferent innervation. Nociceptive afferents innervate lamina I and II, while cutaneous mechanosensory afferents primarily innervate sensory interneurons that are located in lamina III-IV. In this study, we outline a combinatorial transcription factor code that defines nine different inhibitory and excitatory interneuron populations in laminae III-IV of the postnatal cord. This transcription factor code reveals a high degree of molecular diversity in the neurons that make up laminae III-IV, and it lays the foundation for systematically analyzing and manipulating these different neuronal populations to assess their function. In addition, we find that many of the transcription factors that are expressed in the dorsal spinal cord at early postnatal times continue to be expressed in the adult, raising questions about their function in mature neurons and opening the door to their genetic manipulation in adult animals.

Nutritional interventions for liver-transplanted patients.

BACKGROUND: Malnutrition is a common problem for patients waiting for orthotopic liver transplantation and a risk factor for post-transplant morbidity. The decision to initiate enteral or parenteral nutrition, to which patients and at which time, is still debated. The effects of nutritional supplements given before or after liver transplantation, or both, still remains unclear. OBJECTIVES: The aim of this review was to assess the beneficial and harmful effects of enteral and parenteral nutrition as well as oral nutritional supplements administered to patients before and after liver transplantation. SEARCH METHODS: We searched the Cochrane Hepato-Biliary Group Controlled Trials Register (March 2012), the Cochrane Central Register of Controlled Trials (Issue 2 of 12, 2012) in The Cochrane Library, MEDLINE (January 1946 to March 2012), EMBASE (January 1974 to March 2012), Science Citation Index Expanded (January 1900 to March 2012), Social Science Citation Index (January 1961 to October 2010), and reference lists of articles. Manufacturers and experts in the field have also been contacted and relevant journals and conference proceedings were handsearched (from 1997 to October 2010). SELECTION CRITERIA: Randomised clinical trials of parallel or cross-over design evaluating the beneficial or harmful effects of enteral or parenteral nutrition or oral nutritional supplements for patients before and after liver transplantation were eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two authors independently assessed the risk of bias of the trials and extracted data. Dichotomous data were reported as odds ratios (OR) and continuous data as mean differences (MD) along with their corresponding 95% confidence intervals (CI). Meta-analysis was not possible due to clinical heterogeneity of included interventions. MAIN RESULTS: Thirteen trials met the inclusion criteria. Four publications did not report outcomes pre-defined in the review protocol, or other clinically relevant outcomes and additional data could not be obtained. Nine trials could provide data for the review. Most of the 13 included trials were small and at high risk of bias. Meta-analyses were not possible due to clinical heterogeneity of the interventions.No interventions that were likely to be beneficial were identified.For interventions of unknown effectiveness,postoperative enteral nutrition compared with postoperative parenteral nutrition seemed to have no beneficial or harmful effects on clinical outcomes. Parenteral nutrition containing protein, fat, carbohydrates, and branched-chain amino acids with or without alanyl-glutamine seemed to have no beneficial effect on the outcomes of one and three years survival when compared with a solution of 5% dextrose and normal saline. Enteral immunonutrition with Supportan® seemed to have no effect on occurrence of immunological rejection when compared with enteral nutrition with Fresubin®.There is weak evidence that, compared with standard dietary advice, adding a nutritional supplement to usual diet for patients during the waiting time for liver transplantation had an effect on clinical outcomes after liver transplantation. The combination of enteral nutrition plus parenteral nutrition plus glutamine-dipeptide seemed to be beneficial in reducing length of hospital stay after liver transplantation compared with standard parenteral nutrition (mean difference (MD) -12.20 days; 95% CI -20.20 to -4.00). There is weak evidence that the use of parenteral nutrition plus branched-chain amino acids had an effect on clinical outcomes compared with standard parenteral nutrition, but each was beneficial in reducing length of stay in intensive care unit compared to a standard glucose solution (MD -2.40; 95% CI -4.29 to -0.51 and MD -2.20 days; 95% CI -3.79 to -0.61). There is weak evidence that adding omega-3 fish oil to parenteral nutrition reduced the length of hospital stay after liver transplantation (mean difference -7.1 days; 95% CI -13.02 to -1.18) and the length of stay in intensive care unit after liver transplantation (MD -1.9 days; 95% CI -1.9 to -0.22).For interventions unlikely to be beneficial, there is a significant increased risk in acute rejections in malnourished patients with a history of encephalopathy and treated with the nutritional supplement Ensure® compared with usual diet only (MD 0.70 events per patient; 95% CI 0.08 to 1.32). AUTHORS' CONCLUSIONS: We were unable to identify nutritional interventions for liver transplanted patients that seemed to offer convincing benefits. Further randomised clinical trials with low risk of bias and powerful sample sizes are needed.

The tyrosine phosphatase Shp2 acts downstream of GDNF/Ret in branching morphogenesis of the developing mouse kidney.

The tyrosine phosphatase Shp2 acts downstream of various growth factors, hormones or cytokine receptors. Mutations of the Shp2 gene are associated with several human diseases. Here we have ablated Shp2 in the developing kidneys of mice, using the ureteric bud epithelium-specific Hoxb7/Cre. Mutant mice produced a phenotype that is similar to mutations of the genes of the GDNF/Ret receptor system, that is: strongly reduced ureteric bud branching and downregulation of the Ret target genes Etv4 and Etv5. Shp2 mutant embryonic kidneys also displayed reduced cell proliferation at the branch tips and branching defects, which could not be overcome by GDNF in organ culture. We also examined compound mutants of Shp2 and Sprouty1, which is an inhibitor of receptor tyrosine kinase signaling in the kidney. Sprouty1 single mutants produce supernumerary ureteric buds, which branch excessively. Sprouty1 mutants rescued branching deficits in Ret(-/-) and GDNF(-/-) kidneys. Sprouty1; Shp2 double mutants showed no rescue of kidney branching. Our data thus indicate an intricate interplay of Shp2 and Sprouty1 in signaling downstream of receptor tyrosine kinases during kidney development. Apparently, Shp2 mediates not only GDNF/Ret but also signaling by other receptor tyrosine kinases in branching morphogenesis of the embryonic kidney.

Genetic dissection of rhythmic motor networks in mice.

Simple motor behaviors such as locomotion and respiration involve rhythmic and coordinated muscle movements that are generated by central pattern generator (CPG) networks in the spinal cord and hindbrain. These CPG networks produce measurable behavioral outputs and thus represent ideal model systems for studying the operational principles that the nervous system uses to produce specific behaviors. Recent advances in our understanding of the transcriptional code that controls neuronal development have provided an entry point into identifying and targeting distinct neuronal populations that make up locomotor CPG networks in the spinal cord. This has spurred the development of new genetic approaches to dissect and manipulate neuronal networks both in the spinal cord and hindbrain. Here we discuss how the advent of molecular genetics together with anatomical and physiological methods has begun to revolutionize studies of the neuronal networks controlling rhythmic motor behaviors in mice.

The tyrosine phosphatase Shp2 in development and cancer.

Deregulation of signaling pathways, through mutation or other molecular changes, can ultimately result in disease. The tyrosine phosphatase Shp2 has emerged as a major regulator of receptor tyrosine kinase (RTK) and cytokine receptor signaling. In the last decade, germline mutations in the human PTPN11 gene, encoding Shp2, were linked to Noonan (NS) and LEOPARD syndromes, two multisymptomatic developmental disorders that are characterized by short stature, craniofacial defects, cardiac defects, and mental retardation. Somatic Shp2 mutations are also associated with several types of human malignancies, such as the most common juvenile leukemia, juvenile myelomonocytic leukemia (JMML). Whereas NS and JMML are caused by gain-of-function (GOF) mutations of Shp2, loss-of-function (LOF) mutations are thought to be associated with LEOPARD syndrome. Animal models that carry conditional LOF and GOF mutations have allowed a better understanding of the mechanism of Shp2 function in disease, and shed light on the role of Shp2 in signaling pathways that control decisive events during embryonic development or during cellular transformation/tumorigenesis.

The tyrosine phosphatase Shp2 (PTPN11) directs Neuregulin-1/ErbB signaling throughout Schwann cell development.

The nonreceptor tyrosine phosphatase Shp2 (PTPN11) has been implicated in tyrosine kinase, cytokine, and integrin receptor signaling. We show here that conditional mutation of Shp2 in neural crest cells and in myelinating Schwann cells resulted in deficits in glial development that are remarkably similar to those observed in mice mutant for Neuregulin-1 (Nrg1) or the Nrg1 receptors, ErbB2 and ErbB3. In cultured Shp2 mutant Schwann cells, Nrg1-evoked cellular responses like proliferation and migration were virtually abolished, and Nrg1-dependent intracellular signaling was altered. Pharmacological inhibition of Src family kinases mimicked all cellular and biochemical effects of the Shp2 mutation, implicating Src as a primary Shp2 target during Nrg1 signaling. Together, our genetic and biochemical analyses demonstrate that Shp2 is an essential component in the transduction of Nrg1/ErbB signals.

[Non-physician health care providers for the treatment and care of the chronically ill (focusing on DMP diagnoses)]. / Nicht-ärztliche Heilpersonen in der Betreuung und Behandlung chronlsch Kranker (Schwerpunkt: DMP-Diagnosen).

BACKGROUND: This systematic review will investigate the question of how non-physician health care providers may be involved in the care and treatment of patients with chronic disease and which role they could play within the scope of the German Disease Management Programmes (DMP). METHODS: This article is limited to the German DMP diagnoses asthma, COPD, coronary heart disease, and type-1 and -2 diabetes mellitus. Several databases were systematically searched to find national and international studies with interventions carried out by non-physician health care providers such as nurses, dieticians, physiotherapists or occupational therapists. RESULTS: More than 300 studies and reviews were included in this systematic review. Nurses and dieticians were by far the prevailing professional groups performing the largest number of the interventions identified. Transferring. the results of the literature review to the German setting, non-physician health care providers could both undertake certain tasks on their own responsibility and provide other services in support of the medical treatment of the chronically ill. Some interventions are given as examples.

Mutant desmocollin-2 causes arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically heterogeneous heart-muscle disorder characterized by progressive fibrofatty replacement of right ventricular myocardium and an increased risk of sudden cardiac death. Mutations in desmosomal proteins that cause ARVC have been previously described; therefore, we investigated 88 unrelated patients with the disorder for mutations in human desmosomal cadherin desmocollin-2 (DSC2). We identified a heterozygous splice-acceptor-site mutation in intron 5 (c.631-2A-->G) of the DSC2 gene, which led to the use of a cryptic splice-acceptor site and the creation of a downstream premature termination codon. Quantitative analysis of cardiac DSC2 expression in patient specimens revealed a marked reduction in the abundance of the mutant transcript. Morpholino knockdown in zebrafish embryos revealed a requirement for dsc2 in the establishment of the normal myocardial structure and function, with reduced desmosomal plaque area, loss of the desmosome extracellular electron-dense midlines, and associated myocardial contractility defects. These data identify DSC2 mutations as a cause of ARVC in humans and demonstrate that physiologic levels of DSC2 are crucial for normal cardiac desmosome formation, early cardiac morphogenesis, and cardiac function.

Racing, ornamental and city pigeons carry shiga toxin producing Escherichia coli (STEC) with different Shiga toxin subtypes, urging further analysis of their epidemiological role in the spread of STEC.

Pigeons are known to shed zoonotic pathogens. Therefore, in this study a total of 366 droppings from pigeons were analysed using PCR and DNA-DNA-hybridization for Shiga toxin producing E. coli (STEC). Specimens were collected from three different groups of pigeons: 247 collective and 3 individual droppings from racing pigeons, 26 collective and 40 individual from ornamental pigeons as well as 50 collective droppings from city pigeons. Initial screening experiments revealed a total 245 (66.9%) droppings to be Shiga toxin gene positive. Of these 36% were positive for stx1, 9% for stx2 and 37% for stx2f. Prevalence significantly (p < 0.001) differed in regard to the pigeon groups examined. Droppings from racing pigeons showed prevalence of 45.6% for stx1, 3.2% for stx2, and 33.2% for stx2f, while the distribution of stx-positive specimens was more even in ornamental pigeons (15% stx1, 27% stx2, and 26% stx2f). In specimens from city pigeons, stx2f was found to be most prevalent with 76% (2% stx1, 16% stx2). In 161 samples, stx genes were detected by PCR as well as DNA-DNA-hybridization. From these 161 samples, 20 were randomly chosen for isolation of STEC. A total of 27 STEC strains were isolated from 13 of these 20 samples. Six of the STEC were positive for stx1, 21 harbored stx2f. Further typing for virulence factor genes revealed the existence of eae in 4 of the 6 stx1-positive strains, as well as in 19 of the 21 stx2f-positive strains. eae is known to be crucially involved in the ability of E. coli strains to cause the "attaching and effacing" lesion in the gut, while stx2fSTEC are assumed to be host specific for pigeons. Here we report the first description of stx1- and eae-positive STEC strains in pigeons from Germany, especially in racing and ornamental pigeons. Taking into account the close contact between fanciers and pigeons, these findings warrant a more critical appraisal of these zoonotic pathogens in pigeons.

Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with fibrofatty replacement of cardiac myocytes, ventricular tachyarrhythmias and sudden cardiac death. In 32 of 120 unrelated individuals with ARVC, we identified heterozygous mutations in PKP2, which encodes plakophilin-2, an essential armadillo-repeat protein of the cardiac desmosome. In two kindreds with ARVC, disease was incompletely penetrant in most carriers of PKP2 mutations.

Requirement of plakophilin 2 for heart morphogenesis and cardiac junction formation.

Plakophilins are proteins of the armadillo family that function in embryonic development and in the adult, and when mutated can cause disease. We have ablated the plakophilin 2 gene in mice. The resulting mutant mice exhibit lethal alterations in heart morphogenesis and stability at mid-gestation (E10.5-E11), characterized by reduced trabeculation, disarrayed cytoskeleton, ruptures of cardiac walls, and blood leakage into the pericardiac cavity. In the absence of plakophilin 2, the cytoskeletal linker protein desmoplakin dissociates from the plaques of the adhering junctions that connect the cardiomyocytes and forms granular aggregates in the cytoplasm. By contrast, embryonic epithelia show normal junctions. Thus, we conclude that plakophilin 2 is important for the assembly of junctional proteins and represents an essential morphogenic factor and architectural component of the heart.

Tyrosine kinase receptor RON functions downstream of the erythropoietin receptor to induce expansion of erythroid progenitors.

Erythropoietin (EPO) is required for cell survival during differentiation and for progenitor expansion during stress erythropoiesis. Although signaling pathways may couple directly to docking sites on the EPO receptor (EpoR), additional docking molecules expand the signaling platform of the receptor. We studied the roles of the docking molecules Grb2-associated binder-1 (Gab1) and Gab2 in EPO-induced signal transduction and erythropoiesis. Inhibitors of phosphatidylinositide 3-kinase and Src kinases suppressed EPO-dependent phosphorylation of Gab2. In contrast, Gab1 activation depends on recruitment and phosphorylation by the tyrosine kinase receptor RON, with which it is constitutively associated. RON activation induces the phosphorylation of Gab1, mitogen-activated protein kinase (MAPK), and protein kinase B (PKB) but not of signal transducer and activator of transcription 5 (Stat5). RON activation was sufficient to replace EPO in progenitor expansion but not in differentiation. In conclusion, we elucidated a novel mechanism specifically involved in the expansion of erythroblasts involving RON as a downstream target of the EpoR.