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2.
Cell Tissue Res ; 385(1): 21-35, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33616728

RESUMO

Cholinergic chemosensory cells (CCC) are infrequent epithelial cells with immunosensor function, positioned in mucosal epithelia preferentially near body entry sites in mammals including man. Given their adaptive capacity in response to infection and their role in combatting pathogens, we here addressed the time points of their initial emergence as well as their postnatal development from first exposure to environmental microbiota (i.e., birth) to adulthood in urethra and trachea, utilizing choline acetyltransferase (ChAT)-eGFP reporter mice, mice with genetic deletion of MyD88, toll-like receptor-2 (TLR2), TLR4, TLR2/TLR4, and germ-free mice. Appearance of CCC differs between the investigated organs. CCC of the trachea emerge during embryonic development at E18 and expand further after birth. Urethral CCC show gender diversity and appear first at P6-P10 in male and at P11-P20 in female mice. Urethrae and tracheae of MyD88- and TLR-deficient mice showed significantly fewer CCC in all four investigated deficient strains, with the effect being most prominent in the urethra. In germ-free mice, however, CCC numbers were not reduced, indicating that TLR2/4-MyD88 signaling, but not vita-PAMPs, governs CCC development. Collectively, our data show a marked postnatal expansion of CCC populations with distinct organ-specific features, including the relative impact of TLR2/4-MyD88 signaling. Strong dependency on this pathway (urethra) correlates with absence of CCC at birth and gender-specific initial development and expansion dynamics, whereas moderate dependency (trachea) coincides with presence of first CCC at E18 and sex-independent further development.


Assuntos
Técnicas Biossensoriais/métodos , Colinérgicos/metabolismo , Células Epiteliais/metabolismo , Imunidade Inata/imunologia , Traqueia/fisiologia , Uretra/fisiologia , Animais , Masculino , Camundongos
3.
Int J Mol Sci ; 22(7)2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33808081

RESUMO

In the present investigation, we examined whether a change in whole body energy fluxes could affect ovarian follicular development, employing mice ectopically expressing uncoupling protein 1 in skeletal muscle (UCP1-TG). Female UCP1-TG and wild-type (WT) mice were dissected at the age of 12 weeks. Energy intake and expenditure, activity, body weight and length, and body composition were measured. Plasma insulin, glucose, leptin, plasma fibroblast growth factor 21 (FGF21) and plasma insulin-like growth factor 1 (IGF1) levels were analyzed and ovarian follicle and corpus luteum numbers were counted. IGF1 signaling was analyzed by immunohistochemical staining for the activation of insulin receptor substrate 1/2 (IRS1/2) and AKT. UCP1-TG female mice had increased energy expenditure, reduced body size, maintained adiposity, and decreased IGF1 concentrations compared to their WT littermates, while preantral and antral follicle numbers were reduced by 40% and 60%, respectively. Corpora lutea were absent in 40% of the ovaries of UCP1-TG mice. Phospho-IRS1, phospho-AKT -Ser473 and -Thr308 immunostaining was present in the granulosa cells of antral follicles in WT ovaries, but faint to absent in the antral follicles of UCP1-TG mice. In conclusion, the reduction in circulating IGF1 levels due to the ectopic expression of UCP1 is associated with reduced immunostaining of the IRS1-PI3/AKT pathway, which may negatively affect ovarian follicle development and ovulation.


Assuntos
Metabolismo Energético , Folículo Ovariano/crescimento & desenvolvimento , Folículo Ovariano/metabolismo , Proteína Desacopladora 1/metabolismo , Animais , Glicemia/metabolismo , Peso Corporal , Ingestão de Energia/fisiologia , Feminino , Fatores de Crescimento de Fibroblastos/genética , Fatores de Crescimento de Fibroblastos/metabolismo , Células da Granulosa/metabolismo , Proteínas Substratos do Receptor de Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Camundongos Transgênicos , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteína Desacopladora 1/genética
4.
Cell Mol Life Sci ; 75(1): 49-65, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28801754

RESUMO

The chemical variability of the intestinal lumen requires the presence of molecular receptors detecting the various substances naturally occurring in the diet and as a result of the activity of the microbiota. Despite their early discovery, intestinal bitter taste receptors (Tas2r) have not yet been assigned an unambiguous physiological function. Recently, using a CRE-recombinant approach we showed that the Tas2r131 gene is expressed in a subset of mucin-producing goblet cells in the colon of mice. Moreover, we also demonstrated that the expression of the Tas2r131 locus is not restricted to this region. In the present study we aimed at characterizing the presence of positive cells also in other gastrointestinal regions. Our results show that Tas2r131+ cells appear in the jejunum and the ileum, and are absent from the stomach and the duodenum. We identified the positive cells as a subpopulation of deep-crypt Paneth cells in the ileum, strengthening the notion of a defensive role for Tas2rs in the gut. To get a broader perspective on the expression of bitter taste receptors in the alimentary canal, we quantified the expression of all 35 Tas2r genes along the gastrointestinal tract by qRT-PCR. We discovered that the number and expression level of Tas2r genes profoundly vary along the alimentary canal, with the stomach and the colon expressing the largest subsets.


Assuntos
Trato Gastrointestinal/metabolismo , Celulas de Paneth/metabolismo , Receptores Acoplados a Proteínas G/genética , Animais , Feminino , Trato Gastrointestinal/citologia , Perfilação da Expressão Gênica , Íleo/citologia , Íleo/metabolismo , Mucosa Intestinal/metabolismo , Intestinos/citologia , Jejuno/citologia , Jejuno/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Transgênicos , Filogenia , Receptores Acoplados a Proteínas G/classificação , Receptores Acoplados a Proteínas G/metabolismo
5.
J Neurosci ; 35(26): 9717-29, 2015 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-26134654

RESUMO

Taste perception begins in the oral cavity by interactions of taste stimuli with specific receptors. Specific subsets of taste receptor cells (TRCs) are activated upon tastant stimulation and transmit taste signals to afferent nerve fibers and ultimately to the brain. How specific TRCs impinge on the innervating nerves and how the activation of a subset of TRCs leads to the discrimination of tastants of different qualities and intensities is incompletely understood. To investigate the organization of taste circuits, we used gene targeting to express the transsynaptic tracer barley lectin (BL) in the gustatory system of mice. Because TRCs are not synaptically connected with the afferent nerve fibers, we first analyzed tracer production and transfer within the taste buds (TBs). Surprisingly, we found that BL is laterally transferred across all cell types in TBs of mice expressing the tracer under control of the endogenous Tas1r1 and Tas2r131 promotor, respectively. Furthermore, although we detected the BL tracer in both ganglia and brain, we also found local low-level Tas1r1 and Tas2r131 gene, and thus tracer expression in these tissues. Finally, we identified the Tas1r1 and Tas2r131-expressing cells in the peripheral and CNS using a binary genetic approach. Together, our data demonstrate that genetic transsynaptic tracing from bitter and umami receptor cells does not selectively label taste-specific neuronal circuits and reveal local taste receptor gene expression in the gustatory ganglia and the brain. SIGNIFICANCE STATEMENT: Previous papers described the organization of taste pathways in mice expressing a transsynaptic tracer from transgenes in bitter or sweet/umami-sensing taste receptor cells. However, reported results differ dramatically regarding the numbers of synapses crossed and the reduction of signal intensity after each transfer step. Nevertheless, all groups claimed this approach appropriate for quality-specific visualization of taste pathways. In the present study, we demonstrate that genetic transsynaptic tracing originating from umami and bitter taste receptor cells does not selectively label taste quality-specific neuronal circuits due to lateral transfer of the tracer in the taste bud and taste receptor expression in sensory ganglia and brain. Moreover, we visualized for the first time taste receptor-expressing cells in the PNS and CNS.


Assuntos
Encéfalo/citologia , Gânglios/citologia , Regulação da Expressão Gênica/genética , Receptores Acoplados a Proteínas G/metabolismo , Células Receptoras Sensoriais/metabolismo , Animais , Descarboxilases de Aminoácido-L-Aromático/metabolismo , Encéfalo/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Lectinas/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Camundongos , Camundongos Transgênicos , Fosfolipase C beta/metabolismo , RNA Mensageiro/metabolismo , Receptores Acoplados a Proteínas G/genética , Papilas Gustativas/citologia , Aglutininas do Germe de Trigo/metabolismo
6.
J Neurosci ; 35(48): 15984-95, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-26631478

RESUMO

Activation of taste buds triggers the release of several neurotransmitters, including ATP and serotonin (5-hydroxytryptamine; 5-HT). Type III taste cells release 5-HT directly in response to acidic (sour) stimuli and indirectly in response to bitter and sweet tasting stimuli. Although ATP is necessary for activation of nerve fibers for all taste stimuli, the role of 5-HT is unclear. We investigated whether gustatory afferents express functional 5-HT3 receptors and, if so, whether these receptors play a role in transmission of taste information from taste buds to nerves. In mice expressing GFP under the control of the 5-HT(3A) promoter, a subset of cells in the geniculate ganglion and nerve fibers in taste buds are GFP-positive. RT-PCR and in situ hybridization confirmed the presence of 5-HT(3A) mRNA in the geniculate ganglion. Functional studies show that only those geniculate ganglion cells expressing 5-HT3A-driven GFP respond to 10 µM 5-HT and this response is blocked by 1 µM ondansetron, a 5-HT3 antagonist, and mimicked by application of 10 µM m-chlorophenylbiguanide, a 5-HT3 agonist. Pharmacological blockade of 5-HT3 receptors in vivo or genetic deletion of the 5-HT3 receptors reduces taste nerve responses to acids and other taste stimuli compared with controls, but only when urethane was used as the anesthetic. We find that anesthetic levels of pentobarbital reduce taste nerve responses apparently by blocking the 5-HT3 receptors. Our results suggest that 5-HT released from type III cells activates gustatory nerve fibers via 5-HT3 receptors, accounting for a significant proportion of the neural taste response.


Assuntos
Receptores 5-HT3 de Serotonina/metabolismo , Células Receptoras Sensoriais/fisiologia , Transdução de Sinais/fisiologia , Papilas Gustativas/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Trifosfato de Adenosina/farmacologia , Adjuvantes Anestésicos/farmacologia , Animais , Feminino , Gânglio Geniculado/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Pentobarbital/farmacologia , Receptores Purinérgicos P2X3/metabolismo , Receptores 5-HT3 de Serotonina/genética , Células Receptoras Sensoriais/efeitos dos fármacos , Serotonina/metabolismo , Serotonina/farmacologia , Transdução de Sinais/efeitos dos fármacos , Estilbamidinas/metabolismo , Paladar/genética , Paladar/fisiologia , Papilas Gustativas/efeitos dos fármacos , Transducina/metabolismo
7.
Appl Environ Microbiol ; 82(19): 5940-50, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27474715

RESUMO

UNLABELLED: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain EDL933 harbors multiple prophage-associated open reading frames (ORFs) in its genome which are highly homologous to the chromosomal nanS gene. The latter is part of the nanCMS operon, which is present in most E. coli strains and encodes an esterase which is responsible for the monodeacetylation of 5-N-acetyl-9-O-acetyl neuraminic acid (Neu5,9Ac2). Whereas one prophage-borne ORF (z1466) has been characterized in previous studies, the functions of the other nanS-homologous ORFs are unknown. In the current study, the nanS-homologous ORFs of EDL933 were initially studied in silico Due to their homology to the chromosomal nanS gene and their location in prophage genomes, we designated them nanS-p and numbered the different nanS-p alleles consecutively from 1 to 10. The two alleles nanS-p2 and nanS-p4 were selected for production of recombinant proteins, their enzymatic activities were investigated, and differences in their temperature optima were found. Furthermore, a function of these enzymes in substrate utilization could be demonstrated using an E. coli C600ΔnanS mutant in a growth medium with Neu5,9Ac2 as the carbon source and supplementation with the different recombinant NanS-p proteins. Moreover, generation of sequential deletions of all nanS-p alleles in strain EDL933 and subsequent growth experiments demonstrated a gene dose effect on the utilization of Neu5,9Ac2 Since Neu5,9Ac2 is an important component of human and animal gut mucus and since the nutrient availability in the large intestine is limited, we hypothesize that the presence of multiple Neu5,9Ac2 esterases provides them a nutrient supply under certain conditions in the large intestine, even if particular prophages are lost. IMPORTANCE: In this study, a group of homologous prophage-borne nanS-p alleles and two of the corresponding enzymes of enterohemorrhagic E. coli (EHEC) O157:H7 strain EDL933 that may be important to provide alternative genes for substrate utilization were characterized.


Assuntos
Escherichia coli O157/genética , Prófagos/genética , Ácidos Siálicos/metabolismo , Simulação por Computador , Escherichia coli O157/crescimento & desenvolvimento , Escherichia coli O157/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Fases de Leitura Aberta , Prófagos/metabolismo , Deleção de Sequência
8.
FASEB J ; 29(1): 164-72, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25342133

RESUMO

Dysregulation of thyroid hormones triiodothyronine and thyroxine (T3/T4) can impact metabolism, body composition, and development. Thus, it is critical to identify novel mechanisms that impact T3/T4 production. We found that type 2 taste receptors (TAS2Rs), which are activated by bitter-tasting compounds such as those found in many foods and pharmaceuticals, negatively regulate thyroid-stimulating hormone (TSH)-dependent Ca(2+) increases and TSH-dependent iodide efflux in thyrocytes. Immunohistochemical Tas2r-dependent reporter expression and real-time PCR analyses reveal that human and mouse thyrocytes and the Nthy-Ori 3-1 human thyrocyte line express several TAS2Rs. Five different agonists for thyrocyte-expressed TAS2Rs reduced TSH-dependent Ca(2+) release in Nthy-Ori 3-1 cells, but not basal Ca(2+) levels, in a dose-dependent manner. Ca(2+) responses were unaffected by 6-n-propylthiouracil, consistent with the expression of an unresponsive variant of its cognate receptor, TAS2R38, in these cells. TAS2R agonists also inhibited basal and TSH-dependent iodide efflux. Furthermore, a common TAS2R42 polymorphism is associated with increased serum T4 levels in a human cohort. Our findings indicate that TAS2Rs couple the detection of bitter-tasting compounds to changes in thyrocyte function and T3/T4 production. Thus, TAS2Rs may mediate a protective response to overingestion of toxic materials and could serve as new druggable targets for therapeutic treatment of hypo- or hyperthyroidism.


Assuntos
Receptores Acoplados a Proteínas G/metabolismo , Glândula Tireoide/metabolismo , Adulto , Animais , Cálcio/metabolismo , Linhagem Celular , Feminino , Expressão Gênica , Humanos , Imuno-Histoquímica , Ligantes , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/genética , Glândula Tireoide/citologia , Hormônios Tireóideos/metabolismo , Tireotropina/metabolismo , Distribuição Tecidual
9.
Appl Opt ; 55(25): 7138-41, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27607293

RESUMO

Lenses with high numerical aperture are required for images with very high spatial resolution, which is difficult to realize in the x-ray range because of low-refraction-index decrement and relatively high absorption of x-rays in the material. However, such an aperture can be realized by means of a mosaic lens, as shown in this work.

10.
Chem Senses ; 40(9): 627-39, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26377344

RESUMO

The type 2 taste receptors (Tas2rs) comprise a large family of G protein-coupled receptors that recognize compounds bitter to humans and aversive to vertebrates. Tas2rs are expressed in both gustatory and nongustatory tissues, however, identification and functional analyses of T2R-expressing cells have been difficult in most tissues. To overcome these limitations and to be able to manipulate Tas2r-expressing cells in vivo, we used gene-targeting to generate a Tas2r131-specific Cre knock-in mouse strain. We then employed a binary genetic approach to characterize Cre-mediated recombination in these animals and to investigate Tas2r131 expression during postnatal development. We demonstrate that a Cre-activated fluorescent reporter reliably visualizes Tas2r131-cells in gustatory tissue. We show that the onset of Tas2r131 as well as of α-Gustducin expression is initiated at different developmental stages depending on the type of taste bud. Furthermore, the number of Tas2r131- and α-Gustducin-expressing cells increased during postnatal development. Our results demonstrate that the Tas2r131-expressing cells constitute a subpopulation of α-Gustducin positive cells at all stages. We detected Tas2r131-expressing cells in several nongustatory tissues including lung, trachea, ovary, ganglia, and brain. Thus, the Tas2r131-Cre strain will help to dissect the functional role of Tas2r131 cells in both gustatory and nongustatory tissues in the future.


Assuntos
Integrases/genética , Receptores Acoplados a Proteínas G/genética , Recombinação Genética , Papilas Gustativas/metabolismo , Animais , Genes Reporter , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Genótipo , Hibridização in Situ Fluorescente , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia de Fluorescência , Receptores Acoplados a Proteínas G/metabolismo , Transducina/genética , Transducina/metabolismo
11.
Chem Senses ; 40(6): 413-25, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25940069

RESUMO

Transient receptor potential channel subfamily M member 5 (TRPM5) is an important downstream signaling component in a subset of taste receptor cells making it a potential target for taste modulation. Interestingly, TRPM5 has been detected in extra-oral tissues; however, the function of extra-gustatory TRPM5-expressing cells is less well understood. To facilitate visualization and manipulation of TRPM5-expressing cells in mice, we generated a Cre knock-in TRPM5 allele by homologous recombination. We then used the novel TRPM5-IRES-Cre mouse strain to report TRPM5 expression by activating a τGFP transgene. To confirm faithful coexpression of τGFP and TRPM5 we generated and validated a new anti-TRPM5 antiserum enabling us to analyze acute TRPM5 protein expression. τGFP cells were found in taste bud cells of the vallate, foliate, and fungiform papillae as well as in the palate. We also detected TRPM5 expression in several other tissues such as in the septal organ of Masera. Interestingly, in the olfactory epithelium of adult mice acute TRPM5 expression was detected in only one (short microvillar cells) of two cell populations previously reported to express TRPM5. The TRPM5-IC mouse strain described here represents a novel genetic tool and will facilitate the study and tissue-specific manipulation of TRPM5-expressing cells in vivo.


Assuntos
Canais de Cátion TRPM/metabolismo , Alelos , Animais , Anticorpos/imunologia , Feminino , Trato Gastrointestinal/metabolismo , Técnicas de Introdução de Genes , Genótipo , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mucosa Olfatória/metabolismo , Palato/metabolismo , Canais de Cátion TRPM/genética , Canais de Cátion TRPM/imunologia , Papilas Gustativas/metabolismo , Língua/metabolismo
12.
Hum Mol Genet ; 21(3): 656-63, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22052287

RESUMO

Friedreich's ataxia is an inherited neurodegenerative disease caused by the reduced expression of the mitochondrially active protein frataxin. We have previously shown that mice with a hepatocyte-specific frataxin knockout (AlbFxn(-/-)) develop multiple hepatic tumors in later life. In the present study, hepatic carbohydrate metabolism in AlbFxn(-/-) mice at an early and late life stage was analyzed. In young (5-week-old) AlbFxn(-/-) mice hepatic ATP, glucose-6-phosphate and glycogen levels were found to be reduced by ∼74, 80 and 88%, respectively, when compared with control animals. This pronounced ATP, G6P and glycogen depletion in the livers of young mice reverted in older animals: while half of the mice die before 30 weeks of age, the other half reaches 17 months of age and exhibits glycogen, G6P and ATP levels similar to those in age-matched controls. A key event in this respect seems to be the up-regulation of GLUT1, the predominant glucose transporter in fetal liver parenchyma, which became evident in AlbFxn(-/-) mice being 5-12 weeks of age. The most significant histological findings in animals being 17 or 22 months of age were the appearance of multiple clear cell, mixed cell and basophilic foci throughout the liver parenchyma as well as the development of hepatocellular adenomas and carcinomas. The hepatocarcinogenic process in AlbFxn(-/-) mice shows remarkable differences regarding carbohydrate metabolism alterations when compared with all other chemically and virally driven liver cancer models described up to now.


Assuntos
Metabolismo dos Carboidratos , Proteínas de Ligação ao Ferro/genética , Neoplasias Hepáticas Experimentais/metabolismo , Proteínas Mitocondriais/genética , Trifosfato de Adenosina/metabolismo , Animais , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Glucose-6-Fosfato/metabolismo , Glicogênio/metabolismo , Glicogênio Sintase , Quinase 3 da Glicogênio Sintase/metabolismo , Hepatócitos/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Fígado/enzimologia , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas Experimentais/etiologia , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Frataxina
13.
J Physiol ; 591(7): 1967-85, 2013 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-23339178

RESUMO

The T1R1 receptor subunit acts as an umami taste receptor in combination with its partner, T1R3. In addition, metabotropic glutamate receptors (brain and taste variants of mGluR1 and mGluR4) are thought to function as umami taste receptors. To elucidate the function of T1R1 and the contribution of mGluRs to umami taste detection in vivo, we used newly developed knock-out (T1R1(-/-)) mice, which lack the entire coding region of the Tas1r1 gene and express mCherry in T1R1-expressing cells. Gustatory nerve recordings demonstrated that T1R1(-/-) mice exhibited a serious deficit in inosine monophosphate-elicited synergy but substantial residual responses to glutamate alone in both chorda tympani and glossopharyngeal nerves. Interestingly, chorda tympani nerve responses to sweeteners were smaller in T1R1(-/-) mice. Taste cell recordings demonstrated that many mCherry-expressing taste cells in T1R1(+/-) mice responded to sweet and umami compounds, whereas those in T1R1(-/-) mice responded to sweet stimuli. The proportion of sweet-responsive cells was smaller in T1R1(-/-) than in T1R1(+/-) mice. Single-cell RT-PCR demonstrated that some single mCherry-expressing cells expressed all three T1R subunits. Chorda tympani and glossopharyngeal nerve responses to glutamate were significantly inhibited by addition of mGluR antagonists in both T1R1(-/-) and T1R1(+/-) mice. Conditioned taste aversion tests demonstrated that both T1R1(-/-) and T1R1(+/-) mice were equally capable of discriminating glutamate from other basic taste stimuli. Avoidance conditioned to glutamate was significantly reduced by addition of mGluR antagonists. These results suggest that T1R1-expressing cells mainly contribute to umami taste synergism and partly to sweet sensitivity and that mGluRs are involved in the detection of umami compounds.


Assuntos
Receptores Acoplados a Proteínas G/fisiologia , Receptores de Glutamato Metabotrópico/fisiologia , Paladar/fisiologia , Animais , Comportamento Animal , Nervo da Corda do Tímpano/fisiologia , Feminino , Nervo Glossofaríngeo/fisiologia , Ácido Glutâmico/farmacologia , Masculino , Camundongos , Camundongos Transgênicos , Subunidades Proteicas/fisiologia , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Papilas Gustativas/fisiologia
14.
Histochem Cell Biol ; 140(2): 137-45, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23436159

RESUMO

The ingestion of dietary protein is of vital importance for the maintenance of fundamental physiological processes. The taste modality umami, with its prototype stimulus, glutamate, is considered to signal the protein content of food. Umami was thought to be mediated by the heterodimeric amino acid receptor, T1R1 + T1R3. Based on knockout studies, additional umami receptors are likely to exist. In addition to amino acids, certain peptides can also elicit and enhance umami taste suggesting that protein breakdown products may contribute to umami taste. The recently deorphanized peptone receptor, GPR92 (also named GPR93; LPAR5), is expressed in gastric enteroendocrine cells where it responds to protein hydrolysates. Therefore, it was of immediate interest to investigate if the receptor GPR92 is expressed in gustatory sensory cells. Using immunohistochemical approaches we found that a large population of cells in murine taste buds was labeled with an GPR92 antibody. A molecular phenotyping of GPR92 cells revealed that the vast majority of GPR92-immunoreactive cells express PLCß2 and can therefore be classified as type II cells. More detailed analyses have shown that GPR92 is expressed in the majority of T1R1-positive taste cells. These results indicate that umami cells may respond not only to amino acids but also to peptides in protein hydrolysates.


Assuntos
Receptores Acoplados a Proteínas G/metabolismo , Papilas Gustativas/citologia , Papilas Gustativas/metabolismo , Animais , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo , Receptores Acoplados a Proteínas G/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
15.
Cell Metab ; 6(4): 280-93, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17908557

RESUMO

Increasing cellular glucose uptake is a fundamental concept in treatment of type 2 diabetes, whereas nutritive calorie restriction increases life expectancy. We show here that increased glucose availability decreases Caenorhabditis elegans life span, while impaired glucose metabolism extends life expectancy by inducing mitochondrial respiration. The histone deacetylase Sir2.1 is found here to be dispensable for this phenotype, whereas disruption of aak-2, a homolog of AMP-dependent kinase (AMPK), abolishes extension of life span due to impaired glycolysis. Reduced glucose availability promotes formation of reactive oxygen species (ROS), induces catalase activity, and increases oxidative stress resistance and survival rates, altogether providing direct evidence for a hitherto hypothetical concept named mitochondrial hormesis or "mitohormesis." Accordingly, treatment of nematodes with different antioxidants and vitamins prevents extension of life span. In summary, these data indicate that glucose restriction promotes mitochondrial metabolism, causing increased ROS formation and cumulating in hormetic extension of life span, questioning current treatments of type 2 diabetes as well as the widespread use of antioxidant supplements.


Assuntos
Caenorhabditis elegans/metabolismo , Glucose/deficiência , Glicólise , Longevidade , Mitocôndrias/metabolismo , Estresse Oxidativo , Proteínas Quinases Ativadas por AMP , Animais , Caenorhabditis elegans/enzimologia , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Respiração Celular , Glucose/metabolismo , Glicólise/genética , Longevidade/genética , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Estresse Oxidativo/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sirtuínas/genética , Sirtuínas/metabolismo
16.
Chem Senses ; 37(9): 897-911, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23010799

RESUMO

Characterization of the peripheral taste system relies on the identification and visualization of the different taste bud cell types. So far, genetic strategies to label taste receptor cells are limited to sweet, sour, and salty detecting cells. To visualize Tas1r1 umami and Tas2r131 bitter sensing cells, we generated animals in which the Tas1r1 and Tas2r131 open reading frames are replaced by expression cassettes containing the fluorescent proteins mCherry or hrGFP, respectively. These animals enabled us to visualize and quantify the entire oral Tas1r1 and Tas2r131 cell populations. Tas1r1-mCherry cells were predominantly detected in fungiform papillae, whereas Tas2r131-hrGFP cells, which are ~4-fold more abundant, were mainly present in foliate and vallate papillae. In the palate, both cell types were similarly distributed. Mice carrying both recombinant alleles demonstrated completely segregated Tas1r1 and Tas2r131 cell populations. Only ~50% of the entire bitter cell population expressed hrGFP, indicating that bitter taste receptor cells express a subset of the bitter receptor repertoire. In extragustatory tissues, mCherry fluorescence was observed in testis and hrGFP fluorescence in testis, thymus, vomeronasal organ, and respiratory epithelium, suggesting that only few extraoral sites express Tas2r131 and Tas1r1 receptors at levels comparable to taste tissue.


Assuntos
Receptores Acoplados a Proteínas G/genética , Alelos , Animais , Técnicas de Introdução de Genes , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Hibridização in Situ Fluorescente , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Fases de Leitura Aberta , Palato/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Papilas Gustativas/metabolismo , Proteína Vermelha Fluorescente
17.
J Bacteriol ; 193(16): 4258, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21705611

RESUMO

Chlamydia psittaci is an obligate intracellular zoonotic pathogen primarily of birds, but it is also known to infect a variety of mammalian species. Here we report the genomes of four strains isolated from sheep (C19/98), pigs (01DC11), cattle (02DC15), and humans (08DC60).


Assuntos
Chlamydophila psittaci/genética , Psitacose/veterinária , Animais , Sequência de Bases , Bovinos , Doenças dos Bovinos/microbiologia , Chlamydophila psittaci/isolamento & purificação , Genoma Bacteriano , Humanos , Mamíferos , Dados de Sequência Molecular , Psitacose/microbiologia , Ovinos , Doenças dos Ovinos/microbiologia , Suínos , Doenças dos Suínos/microbiologia
18.
J Bacteriol ; 193(10): 2662-3, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21441521

RESUMO

Chlamydophila psittaci is an obligate intracellular zoonotic pathogen, mainly of birds. It is the causative agent of psittacosis in birds and humans. Here we report the full-length de novo genome sequence of the avian isolate 6BC, the type strain of the species C. psittaci.


Assuntos
Chlamydophila psittaci/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Animais , Aves , Chlamydophila psittaci/isolamento & purificação , Dados de Sequência Molecular , Análise de Sequência de DNA
19.
Biochem J ; 432(1): 165-72, 2010 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-20819074

RESUMO

DNA-repair mechanisms enable cells to maintain their genetic information by protecting it from mutations that may cause malignant growth. Recent evidence suggests that specific DNA-repair enzymes contain ISCs (iron-sulfur clusters). The nuclearencoded protein frataxin is essential for the mitochondrial biosynthesis of ISCs. Frataxin deficiency causes a neurodegenerative disorder named Friedreich's ataxia in humans. Various types of cancer occurring at young age are associated with this disease, and hence with frataxin deficiency. Mice carrying a hepatocyte-specific disruption of the frataxin gene develop multiple liver tumours for unresolved reasons. In the present study, we show that frataxin deficiency in murine liver is associated with increased basal levels of oxidative DNA base damage. Accordingly, eukaryotic V79 fibroblasts overexpressing human frataxin show decreased basal levels of these modifications, while prokaryotic Salmonella enterica serotype Typhimurium TA104 strains transformed with human frataxin show decreased mutation rates. The repair rates of oxidative DNA base modifications in V79 cells overexpressing frataxin were significantly higher than in control cells. Lastly, cleavage activity related to the ISC-independent repair enzyme 8-oxoguanine glycosylase was found to be unaltered by frataxin overexpression. These findings indicate that frataxin modulates DNA-repair mechanisms probably due to its impact on ISC-dependent repair proteins, linking mitochondrial dysfunction to DNA repair and tumour initiation.


Assuntos
Dano ao DNA , Reparo do DNA/genética , Ataxia de Friedreich/genética , Proteínas de Ligação ao Ferro/genética , Animais , Linhagem Celular , Células Cultivadas , DNA Glicosilases/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patologia , Ataxia de Friedreich/metabolismo , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Proteínas de Ligação ao Ferro/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Mamíferos/genética , Mamíferos/metabolismo , Camundongos , Camundongos Knockout , Mutação , Estresse Oxidativo , Células Procarióticas/metabolismo , Salmonella enterica/genética , Transfecção , Frataxina
20.
Front Behav Neurosci ; 15: 647224, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33994968

RESUMO

As a canary in a coalmine warns of dwindling breathable air, the honeybee can indicate the health of an ecosystem. Honeybees are the most important pollinators of fruit-bearing flowers, and share similar ecological niches with many other pollinators; therefore, the health of a honeybee colony can reflect the conditions of a whole ecosystem. The health of a colony may be mirrored in social signals that bees exchange during their sophisticated body movements such as the waggle dance. To observe these changes, we developed an automatic system that records and quantifies social signals under normal beekeeping conditions. Here, we describe the system and report representative cases of normal social behavior in honeybees. Our approach utilizes the fact that honeybee bodies are electrically charged by friction during flight and inside the colony, and thus they emanate characteristic electrostatic fields when they move their bodies. These signals, together with physical measurements inside and outside the colony (temperature, humidity, weight of the hive, and activity at the hive entrance) will allow quantification of normal and detrimental conditions of the whole colony. The information provided instructs how to setup the recording device, how to install it in a normal bee colony, and how to interpret its data.

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