Sweet taste receptors play roles in artificial sweetener-induced enhanced urine output in mice

Sweet taste receptors found in oral and extra oral tissues play important roles in the regulation of many physiological functions. Studies have shown that urine volume increases during the lifetime exposure to artificial sweeteners. However, the detailed molecular mechanism and the general effects of different artificial sweeteners exposure on urine volume remain unclear. In this study, we investigated the relationship between urinary excretion and the sweet taste receptor expression in mice after three artificial sweeteners exposure in a higher or lower concentration via animal behavioral studies, western blotting, and real-time quantitative PCR experiment in rodent model. Our results showed that high dose of acesulfame potassium and saccharin can significantly enhance the urine output and there was a positive correlation between K+ and urination volume. The acesulfame potassium administration assay of T1R3 knockout mice showed that artificial sweeteners may affect the urine output directly through the sweet taste signaling pathway. The expression of T1R3 encoding gene can be up-regulated specifically in bladder but not in kidney or other organs we tested. Through our study, the sweet taste receptors, distributing in many tissues as bladder, were indicated to function in the enhanced urine output. Different effects of long-term exposure to the three artificial sweeteners were shown and acesulfame potassium increased urine output even at a very low concentration.

Current status of ex-vivo liver resection and autologous liver transplantation for end-stage hepatic alveolar echinococcosis

Hepatic alveolar echinococcosis (HAE) is a cosmopolitan zoonosis distribute widely in the northern hemisphere with high estimated 10-year mortality. Radical resection combined with oral albendazole administration are the major methods for HAE treatment, whereas most patients delayed diagnosis and treatment because which was considered as benign disease. For the cases with end-stage HAE could not be treated through conventional hepatectomy, allograft liver transplantation (LT) was regarded as a life-saving technique previously. However, graft shortage, high recurrence rate and long-term immunosuppressive therapy limited its utilization. Since the ex-vivo liver resection and autotransplantation (ERAT) procedure was first used in treating for end-stage HAE in 2011, there are more than 120 HAE cases patients were reported treating in this method up to now. Comparing with LT, ERAT needs neither an organ donor nor long term immunosuppressive therapy, and provide preferable overall survival rates. Based on the conventional ERAT procedure, some modification such as auxiliary partial autologous LT were introduced in the high selected end-stage HAE patients presently. However, the standard procedures for ERAT including surgical details and perioperative management have not been established because of limited reported cases. Also, the present ERAT experience for end-stage HAE treatment are all summarizes by the Chinese surgeon groups. For summarizing the knowledge and experience details, we reviewed present opinions about ERAT for end-stage HAE patients, and presented the future perspectives about this topic in this manuscript. We aimed at discussing the feasibility, indications, preparation, technical details, and postoperative outcomes of ERAT for HAE patients.

Vesicle formation by ultrashort alkyl-phosphonic acids and serine in aqueous solutions

Vesicles possess unique biofilm structures and offer biomimetic advantages for drug and gene delivery. Herein, we report the spontaneous vesicle formation from ultrashort alkyl-phosphonic acids in the presence of amino acids. The aggregation characteristics and self-assembly structures of vesicles in aqueous solution were investigated by using dynamic light scattering, zeta potential, and cryo-transmission electron microscopy. We combined low-field nuclear magnetic resonance and Fourier transform infrared spectroscopy to study the H-proton-induced multilamellar vesicle formation. When we increased the molar fraction of serine, stable and closed spherical vesicles were formed at relatively low critical micelle concentrations. This transition of the self-assembled structure indicates that vesicle formation occurs when the chain length and the magnitude of the surface charge cause a fluctuation in the volume of the vesicle. Density functional theory reveals the critical role of the mixed alkyl-phosphonic acid/amino acid-enhanced electrostatic attraction between the head groups and hydrogen bonds associated with the aggregated states.

Vesicles from the self-assembly of the ultra-small fatty acids with amino acids under aqueous conditions

The properties of vesicles formed from the self-assembly of amphiphilic molecules can mimic the functionality of the natural lipid membranes. In this study, the self-assembly process of the amphiphilic structures formed by the interaction between ultra-small fatty acids [FAs, Cn (n = 4-8)] and amino acids (AAs) to generate vesicles under aqueous conditions were investigated in detail, along with the corresponding dynamic vesiculation mechanisms. Our results showed that the molar ratio of FAs/AAs and the chain length of FAs largely affected the structural characteristics and dispersion of vesicles. The detailed information about the entire size distributions and morphology of obtained vesicles were explored by the cryogenic transmission electron microscopy (Cryo-EM). Fourier transform infrared (FT-IR) spectra and quantum calculations suggested that the intermolecular hydrogen bond and electrostatic interactions between ultra-small molecules (FAs and AAs) during the aggregation processes were responsible for the formation of vesicles, where the hydrogen-bonding effect was dominant. Our findings shed new light on the effective and simple preparation of biological vesicles via ultra-small molecules self-assembly in aqueous solutions, which may have potential applications in vesicle physiology and drug delivery systems, and also get a mature understanding of the fundamental intermolecular interactions in life process.

[Mechanism of hsa-miR-302a-3p-targeted VEGFA in the Inhibition of Proliferation of Gastric Cancer Cell]

OBJECTIVE

To explore the role mechanism of hsa-miR-302a-3p overexpression in the inhibition of proliferation of gastric cancer cell SGC-7901 by targeted-regulating vascular endothelial growth factor A (VEGFA).

METHODS

The cell transfection was used to transfect hsa-miR-302a-3p mimic into miR mimic group and transfect pc-VEGFA into VEGFA group, and the two genes were co-transfected into miR+VEGFA group. The transfection efficiency was detected by RT-PCR and Western blot. The bioinformatics targeting prediction and fluorescein assay were used to verify the targeting relationship between the two genes. Cell proliferation was detected by CCK-8 test, and Transwell assay was used to detect the invasion ability of each group, and scratch assay was used to detect the migration ability of each group. The morphology changes of epithelial-mesenchymal transition (EMT) in cells were observed under microscope. Western blot was used to detect the protein expression levels of survival-related proteins Ki67 and Caspase-3, EMT-related proteins E-cadherin, Vimentin, N-cadherin and Snail and VEGFA downstream target genes p-P38, p-MAPKAPK and p-Hsp27.

RESULTS

VEGFA was the predicted target site of miR-302a-3p. Compared with control group, the number of cells, the invasion and migration rates were also reduced ( P<0.05) in miR mimic group, and the number of cells was increased ( P<0.05) as well as the invasion and migration rates in VEGFA group. Compared with VEGFA group, the number of cells, the invasion and migration rates were also decreased ( P<0.05) in miR+VEGFA group. The protein expression level of E-cadherin was up-regulated ( P<0.05) while the protein expression levels of Vimentin, N-cadherin and Snail were down-regulated ( P<0.05), and the protein expression levels of p-P38, p-MAPKAPK and p-Hsp27 were also down-regulated ( P<0.05).

CONCLUSION

hsa-miR-302a-3p overexpression can inhibit the proliferation and promote apoptosis of gastric cancer cell SGC-7901 by targeting negative regulation of VEGFA expression.

Rapamycin inhibits activation of AMPK-mTOR signaling pathway-induced Alzheimer's disease lesion in hippocampus of rats with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is strongly correlated with Alzheimer's disease (AD). Rapamycin has important uses in oncology, cardiology and transplantation medicine. This study aims to investigate effects of rapamycin on AD in hippocampus of T2DM rat by AMPK/mTOR signaling pathway.

METHODS

Morris water maze test was applied to evaluate the learning and memory abilities. The fasting plasma glucose (FBG), glycosylated haemoglobin, total cholesterol, triglyceride and serum insulin level were measured. RT-qPCR and Western blot analysis were performed to test expression of AMPK and mTOR. Immunohistochemistry was used to detect the Aβ deposition and immunoblotting to test the total tau, p-tau and Aβ precursor APP expressions.

RESULTS

After treated with rapamycin, T2DM rats and rats with T2DM and AD showed increased learning-memory ability, and decreased levels of FBG, glycosylated hemoglobin, total cholesterol, triglyceride and serum insulin, decreased expression of APP and p-tau, increased AMPK mRNA expression and p-AMPK and decreased Aβ deposition, mTOR mRNA expression and p-mTOR.

CONCLUSION

The study demonstrated that rapamycin reduces the risk of AD in T2DM rats and inhibits activation of AMPK-mTOR signaling pathway, thereby improving AD lesion in hippocampus of T2DM rats.

Comparisons of Effects on Intestinal Short-Chain Fatty Acid Concentration after Exposure of Two Glycosidase Inhibitors in Mice

Acarbose and voglibose are the most widely used diabetes drugs as glycosidase inhibitors. In this study, the use of these two inhibitors significantly increased the content of starch in large intestine, and altered the concentration of short-chain fatty acids (SCFAs) by affecting the intestinal microbiota. However, there are some differences in the intestinal microbiome of the two groups of mice, mainly in bacteria such as Bacteroidaceae bacteroides and Desulfovibrionaceae desulfovibrio. The productions of acetate and propionate in caecum in voglibose group were significantly higher than those in acarbose group and two kinds of glycosidase inhibitors were close in the production of butyrate in caecum. The Tax4Fun analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) data indicated that different productions of acetate and propionate between acarbose group and voglibose group may be related to 2-oxoisovalerate dehydrogenase and pyruvate oxidase. In addition, in-vitro experiments suggested that voglibose had less effect on epithelial cells than acarbose after direct stimulation. According to the recent researches of SCFAs produced by intestinal microbiota, our comparative study shown higher concentration of these beneficial fatty acids in the lumen of voglibose-treated mice, which implied a lower level of inflammation.

Diagnostic Significance of Serum Levels of Nerve Growth Factor and Brain Derived Neurotrophic Factor in Diabetic Peripheral Neuropathy

Background

Our study aimed to explore the levels of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) in healthy participants, type 2 diabetes mellitus (T2DM) patients, and diabetic peripheral neuropathy (DPN) patients in order to find their effects on DPN.

Material/Methods

The clinical data of 110 healthy participants (age: 57.3±8.2 year, height: 165.4±5.5 cm, weight: 64.1±7.5 kg), 83 T2DM patients (age: 56.5±7.9 year, height: 164.8±6.2 cm, and weight: 63.6±6.6 kg), and 65 DPN patients (age: 58.2±7.3 year, height: 166.7±6.7 cm, weight: 63.1±5.8 kg) were observed. ELISA was applied to detect serum NGF and BDNF levels. Receiver operating characteristic (ROC) curve analysis was performed to evaluate diagnostic value of serum NGF and BDNF levels in DPN. Logistic regression analysis was performed to analyze risk factors for DPN.

Results

Serum NGF and BDNF levels decreased most in DPN patients. Subsequently, we determined that serum NGF and BDNF levels were correlated with: the course of disease for patients, fasting C-peptide (FCP), 2-hour postprandial C-peptide level (2-h PCP), glycosylated hemoglobin level (HbAlc), and 24-hour urinary microalbumin excretion (24-h UME). ROC curve analysis identified high sensitivity, specificity, and accuracy of NGF and BDNF levels on DPN. Serum levels of NGF and BDNF, course of disease, 2-h PCP level, and postprandial blood glucose level were determined to be risk factors for DPN.

Conclusions

Our study highlights that serum levels of NGF and BDNF might be associated with the occurrence and development of DPN.

Integrated analysis of the RNA-Seq data of liver hepatocellular carcinoma

The present study aimed to explore the genetic changes involved in the liver hepatocellular carcinoma (HCC) development. The RNA-Seq data of 212 HCC tissue samples and 50 normal tissue samples were downloaded using TCGA-Assembler. A total of 4 subgroups were obtained, and 4167, 6279, 5379, and 2548 DEGs were screened in group 1, group 2, group 3, and group 4, respectively. Enrichment analysis found that cell cycle, metabolism, and translation related terms were the most significantly changed functions and pathways. There were 454 genes (1114 pairs), 803 genes (722 pairs), and 788 genes (724 pairs), separately interacted in the condition specific PPI network of group 1, 2, 3, and 4, with MMP2, ATNXN1, F2, and HDAC1 as the hub genes. What's more, using these genes, total 7, 20, 198, and 1 subtype related miRNAs; 35, 50, 47, and 17 subtype related TFs; 1, 1, 0, and 2 subtype related drugs were screened in group 1, 2, 3, and 4, respectively. The integrated biological analysis on RNA-Seq data provided substantial of bio-molecular related to the HCC development. miR-147b, SP1, and Riboflavin were the subtype-related regulator/drug for HCC. The study about the big data of HCC RNA-Seq data reveals the intrinsic gene expression pattern of the tumor, which provides a novel perspective to understand the heterogeneity of pathogenesis in HCC tumorigenesis.

Vesicle formation by proton transfer driven short-tailed fatty acids of C4-C8 chain length in water

Ultrashort single-chain fatty acids self-assemble to form vesicles under certain proton-driven conditions. The protonation provides a larger charge area around the hydrophilic carbonyl headgroups, and proton shift as the key driving parameter was studied. The ultrashort fatty acids (C4-C8) formed stable unilamellar vesicles predominantly through out the whole range of tested pH levels (6.5-9.5). A proton-driven self-assembly process and effects on the phase transition were characterized by dynamic light scattering, transmission electron microscopy and cryo-transmission electron microscopy. In particular, we studied in greater detail the molecular packing characteristics of FA vesicles for geometric reasons and the protonation effect changes the molecular surface charge and further carboxylic acid headgroup motion. This study enhances the understanding of the physicochemical specificity of these membrane vesicles, and may facilitate the alteration of membrane function caused by FAs.

Molecular cloning, characterization, and expression profiles of androgen receptors in spotted scat (Scatophagus argus)

Androgen plays critical roles in vertebrate reproductive systems via androgen receptors (ARs). In the present study, the full-length spotted scat (Scatophagus argus) androgen receptor (sAR) cDNA sequence was cloned from testis. The sAR cDNA measured 2448 bp in length with an open-reading frame of 2289 bp, encoding 763 amino acids. Amino acid alignment analyses showed that the sARs exhibited highly evolutionary conserved functional domains. Phylogenetically, the sARs clustered within the ARβ common vertebrate group. Real-time polymerase chain reaction (RT-PCR) revealed that sAR expression varied in level and distribution throughout the tissues of both females and males. sAR expression was detected during testicular development by quantitative RT-PCR. The results showed that the highest transcription of sARs was observed in the mid-testicular stage, and remained at a high expression level until the late-testicular stage. In addition, the effects of 17α-methyltestosterone (MT) and estrogen (E2) on the expression of sARs in ovaries were determined using quantitative RT-PCR. sAR expression increased at 12 and 24 h post-MT treatment and decreased with E2 treatment. The present study provides preliminary evidence indicating gonadal plasticity of spotted scat under exogenous steroidal hormone treatments. It also provides a theoretical basis for sex reversal and production of artificial pseudo-males for female monosex breeding.

The roles of IL-2 and IL-10 enhance anti-CD45RBmAb immune inhibition in allograft skin

As a new type of immune tolerance inducer, anti-CD45RB monoclonal antibodies (anti-CD45RBmAb) can prolong the graft survival time of animal organs or cell transplantation as well as induce stable immune tolerance. Both interleukin (IL)-2 and IL-10 have important roles in the induction and maintenance of immunological tolerance. However, whether these cytokines combined with anti-CD45RBmAb can promote immune tolerance is poorly understood. Therefore, we investigated the effect of IL-2 and IL-10 in vitro and in vivo on the tolerance induction by anti-CD45RBmAb. The changes of Treg and Th17 cells and Th1/Th2 cytokines in anti-CD45RBmAb induced prolongation of skin allograft survival in mice. The finding of a role for IL-2 is novel, of interest, IL-2 promoted anti-CD45RBmAb-induced CD4(+) T cell differentiation into Treg and Th2 cells and suppressed Th17 and Th1 cells. IL-2 enhanced the induction of immune tolerance by anti-CD45RBmAb and significantly prolonged skin graft survival time in vivo. In contrast, this effect should be demonstrated experimentally by neutralizing IL-2 and inhibition of the effect of anti-CD45RBmAb, and neutralizing IL-10 showed no effect for anti-CD45RBmAb-induced tolerance. These data reveal that IL-2 significantly enhances anti-CD45RBmAb-induced immune tolerance via up-regulated T regulatory (Treg) cells and the balance of Th1/Th2 shifts. Conversely, IL-10 showed no effect on anti-CD45RBmAb-induced tolerance.

In vivo and in vitro inhibitory action of 17β-estradiol and environmental estrogen 4-nonylphenol on gonad-inhibiting hormone (GIH) expression in the eyestalks of Litopenaeus vannamei

The gonad-inhibiting hormone (GIH) belongs to a neuropeptide family synthesized and released in an X-organ sinus gland complex of crustacean eyestalks. GIH inhibits crustacean ovarian maturation by suppressing vitellogenin (Vtg) synthesis, whereas estrogen is responsible for the stimulation of vitellogenesis (not established). In this study, the effects of 17β-estradiol (E2, 10(-6) M), estrogen receptor antagonist tamoxifen (TAM, 10(-6), 10(-7), and 10(-8) M), and the environmental estrogen nonylphenol (NP, 1 μg/L and 100 μg/L) on LvGIH expression in the eyestalks of shrimp were determined by quantitative real-time PCR. Results showed that LvGIH expression decreased significantly during the L. vannamei ovarian maturation cycle. E2 and NP significantly reduced LvGIH transcripts in vivo, but TAM neutralized the inhibitory action of E2 in a dose-dependent manner (P < 0.05). In addition, the LvGIH expression levels decreased significantly in a time-dependent manner (P < 0.05) when ovary fragments were cultured in vitro with E2. The results of this study suggested that estrogen regulates GIH expression in L. vannamei eyestalks. E2 promoted ovarian development not only by directly upregulating vitellogenesis in the hepatopancreas, but it was also capable of downregulating LvGIH expression, which indirectly resulted in the stimulation of L. vannamei vitellogenesis.

Effects of early intraoral acesulfame-K stimulation to mice on the adult's sweet preference and the expression of α-gustducin in fungiform papilla

Exposure to artificial sweetener acesulfame-K (AK) at early development stages may influence the adult sweet preference and the periphery gustatory system. We observed that the intraoral AK stimulation to mice from postnatal day 4 (P4) to weaning decreased the preference thresholds for AK and sucrose solutions in adulthood, with the preference pattern unchanged. The preference scores were increased in the exposure group significantly when compared with the control group at a range of concentrations for AK or sucrose solution. Meanwhile, more α-Gustducin-labeled fungiform taste buds and cells in a single taste bud were induced from week 7 by the early intraoral AK stimulation. However, the growth in the number of α-Gustducin-positive taste bud or positive cell number per taste bud occurred only in the anterior region, the rostral 1-mm part, but not in the intermediate region, the caudal 4-mm part, of the anterior two-third of the tongue containing fungiform papillae. This work extends our previous observations and provides new information about the developmental and regional expression pattern of α-Gustducin in mouse fungiform taste bud under early AK-stimulated conditions.

Thermodynamics of the interaction of sweeteners and lactisole with fullerenols as an artificial sweet taste receptor model

The thermodynamics of the mimetic interaction of lactisole and sweeteners with fullerenols as a synthetic sweet receptor model was elucidated by Isothermal Titration Calorimetry (ITC) technique. The presence of lactisole resulted in great differences in thermodynamics of the sweeteners binding with fullerenols in which lactisole led to much more entropy contribution to the free energy compared with the interaction of sweeteners with fullerenols. Two interaction equilibrium states were found in ITC titration profiles and competitive binding of lactisole and sweeteners with fullerenols was disclosed. Our results indicated that the larger value of the ratio of two equilibrium constant K1/K2, the more effectively lactisole inhibited the sweetness of the sweetener. The combined results of sensory evaluation and ITC thermodynamics revealed that introducing a synthetic receptor model to interact with the sweeteners and inhibitors helps to understand the inhibition mechanism and the thermodynamic basis for the initiation of sweetness inhibition.

Isothermal titration calorimetry study of the interaction of sweeteners with fullerenols as an artificial sweet taste receptor model

A fullerenol-based synthetic sweetness receptor model, consisting of polyhydroxy groups for potential hydrogen bond donor along with a spherical hydrophobic center, was proposed according to the widely accepted sweetness hypothesis. An isothermal titration calorimetry (ITC) technique was used to study mimetic interaction of this sweet receptor model with a series of sweeteners having increasing sweetness intensity. The results showed that ITC is an effective method to provide thorough and precise characterization of the energies of molecular complex formation. Binding of all of the studied sweeteners with fullerenols was found through two sets of site models. More heat was released from sweeter synthetic compounds binding with fullerenols than from less sweet carbohydrates. The results imply that hydrogen bond formation is necessary for the sweeteners to bind to the fullerenol receptor in the first stage, whereas hydrophobic effect and conformation changes that lead to favorable entropy changes occur in most cases. The preliminary results of this study help to cover the lack of information about the thermodynamic basis of understanding of the initiation of the sweet sensation. It also adds complementary physicochemical measurements available for comparison with the sweetness hypothesis. On the other hand, a correlation between the thermodynamic parameters and sweetness intensity has been made as well, which exhibits potential as a useful tool in sensory analysis.

A reliable method to obtain cells of taste buds from fungiform papillae of mice

Taste buds consist of four kinds of cells which have distinct characteristics and play different roles in recognizing chemical compounds contained in foodstuffs. In this study we describe a procedure for separating viable taste bud cells from the fungiform papillae in mice. After sacrifice with CO(2), the mouse tongue was excised and immediately incubated in collagenase II and dispase II. The epithelium with fungiform papillae was then peeled away from underlying tissue and the anterior one-third region was incubated in a solution of 0.25% trypsin and 0.02M ethylene-diamine-tetraacetic acid (EDTA) for 8-12min. Following incubation, a cell suspension was obtained by mechanical dissociation. Cells in suspension were identified as taste bud cells by their morphology and by immunofluorescence. A 0.25% trypan blue staining demonstrated that nearly 90% of these cells remained viable. Micrographs from scanning electron microscopy illustrated that taste buds were dissociated from the fungiform papillae, while maintaining the integrity of the other part of the dissociated lingual epithelium during incubation. Such a method allows acquisition of viable taste cells and will aid further research in the study of gustatory characteristics.

Quantitative study of taste bud distribution within the oral cavity of the postnatal mouse

The aim of this study was to investigate the age-related developmental changes of taste bud distribution within the subpopulations at different postnatal ages in the mouse oral cavity. Developmental changes of taste bud distribution on the soft palate, fungiform, foliate and circumvallate papillae in the mouse oral cavity were examined histologically at different postnatal ages. After paraffin embedding, complete serial sections at 10mum thickness were made and stained by routine hematoxylin-eosin staining methods. Digitised images for each section were examined carefully. The existence of a taste pore was used to identify mature taste buds. A two-way analysis of variance (group versus age) was used to analyse differences in taste bud number and characteristics for each of the developmental changes. An independent measures t-test was used to compare two means. No taste buds with pores were observed at birth within circumvallate and foliate papillae. However, 61% of the circumvallate and 58% of the foliate taste buds contained taste pores at 2 weeks after birth. In contrast, at birth, 55% of the taste buds on the soft palate and only 22% of the taste buds within fungiform papillae contained taste pores. Then, the number of mature taste buds (taste buds with pores) increased rapidly 1 week after birth, resulting in 90% of soft palate taste buds and 32% of fungiform taste buds containing taste pores. These results suggests that the earlier maturation of soft palate taste buds compared with the other populations in the oral cavity raises evidence of their significant role in the taste mechanism, especially in the early life of the mouse.

Regional differences in taste bud distribution and alpha-gustducin expression patterns in the mouse fungiform papilla

The regional differences between distribution patterns and alpha-gustducin expression patterns of the fungiform (FF) taste buds were investigated in the adult mouse, using hematoxylin-eosin staining and immunofluorescence histochemistry on the most anterior region of the tongue (the first millimeter) through the intermediate region of the tongue (the last 1-4 mm). Paraffin sections were prepared from the tip to posterior regions (anterior and intermediate region containing the FF taste buds) of the adult mouse tongue. Results indicate that there were significant regional differences in size and density of taste buds, the cell counts of the single taste bud, and the alpha-gustducin-immunoreactive taste buds between the 2 regions. The taste bud had a characteristic onion-like appearance, and the alpha-gustducin-immunoreactive cell was spindle shaped with elongated processes extending from the base to the pore of the taste buds. These results provide a detailed insight to better understand regional descriptions of mouse taste bud density and size and alpha-gustducin expression with the mouse model.

Differentiation of alpha-gustducin in taste buds of the mouse soft palate and fungiform papillae

We used alpha-gustducin, a type II taste-cell-specific G protein, to investigate the onset of taste transduction and its relation to the development of the soft palate (SP) and fungiform (FF) papillae taste buds in the mouse. Paraffin wax embedded sections were prepared from the SP and anterior region of the tongue of the mouse from birth until postnatal day (PD) 63. No alpha-gustducin-immunoreactive cells were observed on the day of birth. One day later, alpha-gustducin was immunolocalised in taste buds with pores with a relatively higher frequency recorded in the SP as compared with the FF papillae. The immunoreactive cells were spindle shaped with elongated processes extending from the base to the pore of the taste buds. On PD 7, the number of taste buds containing alpha-gustducin-immunoreactive cells in the SP was three times greater than that of FF papillae. Our results indicate that taste transduction is essentially acquired from the time of birth. Moreover, the onset of taste transduction by the SP taste buds developed earlier than that achieved by taste buds in the FF papillae.

Developmental change of α-gustducin expression in the mouse fungiform papilla

Developmental changes in the distribution pattern of taste buds in newborn mouse have not been previously elucidated, and little work has been done to examine the postnatal alteration of the expression of alpha-gustducin in the mouse taste buds. In the present paper, we delineated the development and frequency distribution of the taste buds as well as the immunohistochemical expression of alpha-gustducin, a G protein closely related to the transduction of taste stimuli in the fungiform papilla from the birthday till the age of week 9. At birth, more than 45 taste buds (with or without pores) were observed on the fungiform papilla, then the number of mature taste buds increased rapidly, and resulted in 66% (80.2 +/- 0.6 of 122.2 +/- 1.3) of fungiform papilla taste buds containing taste pores at week 3. By age the total counts of pored taste buds continuously increased and their morphological features became quite discernible. They became ellipse in shape, characterized by distinct pores. Quantitative analysis of alpha-gustducin expression at different postnatal ages revealed a significant increase in the number of immunolabeled taste buds and alpha-gustducin-positive cells in single taste buds from week 1 to 7, by week 7, the number reached the value found in adults (99.3 +/- 0.9 and 8.3 +/- 0.3, respectively). These results indicated that taste buds within fungiform papilla play an important role in the detection of nutrients in the postnatal mouse.

Bacterial community structure and diversity in a century-old manure-treated agroecosystem

Changes in soil microbial community structure and diversity may reflect environmental impact. We examined 16S rRNA gene fingerprints of bacterial communities in six agroecosystems by PCR amplification and denaturing gradient gel electrophoresis (PCR-DGGE) separation. These soils were treated with manure for over a century or different fertilizers for over 70 years. Bacterial community structure and diversity were affected by soil management practices, as evidenced by changes in the PCR-DGGE banding patterns. Bacterial community structure in the manure-treated soil was more closely related to the structure in the untreated soil than that in soils treated with inorganic fertilizers. Lime treatment had little effect on bacterial community structure. Soils treated with P and N-P had bacterial community structures more closely related to each other than to those of soils given other treatments. Among the soils tested, a significantly higher number of bacterial ribotypes and a more even distribution of the bacterial community existed in the manure-treated soil. Of the 99 clones obtained from the soil treated with manure for over a century, two (both Pseudomonas spp.) exhibited 100% similarity to sequences in the GenBank database. Two of the clones were possible chimeras. Based on similarity matching, the remaining 97 clones formed six major clusters. Fifty-six out of 97 were assigned taxonomic units which grouped into five major taxa: alpha-, beta-, and gamma-Proteobacteria (36 clones), Acidobacteria (16 clones), Bacteroidetes (2 clones), Nitrospirae (1 clone), and Firmicutes (1 clone). Forty-one clones remained unclassified. Results from this study suggested that bacterial community structure was closely related to agroecosystem management practices conducted for over 70 years.

Glucokinase and cytosolic phosphoenolpyruvate carboxykinase (GTP) in the human liver. Regulation of gene expression in cultured hepatocytes

Glucokinase and phosphoenolpyruvate carboxykinase are key enzymes of glucose metabolism in the rat liver. The former is considered to be instrumental in regulating glucose hepatic release/uptake according to the glycaemia level, and cytosolic phosphoenolpyruvate carboxykinase is a major flux-generating enzyme for gluconeogenesis. The level of expression of both enzymes and the regulation of their mRNAs in the human liver cell were investigated. Surgical biopsies of liver from patients undergoing partial hepatectomies and parenchymal hepatocytes derived from the biopsies were used to assay glucokinase, hexokinase and phosphoenolpyruvate carboxykinase activities. Hepatocytes were placed in culture and the actions of insulin, glucagon and cAMP on glucokinase and phosphoenolpyruvate carboxykinase mRNAs were studied. The main results are: (a) glucokinase accounts for 95% of the glucose phosphorylation activity of human hepatocytes, although this fact is masked in assays of total liver tissue; (b) glucokinase activity is set at a lower level in human hepatocytes than in rat hepatocytes, and vice-versa for the gluconeogenic enzyme phosphoenolpyruvate carboxykinase; and (c) as previously shown in rat liver, glucokinase and phosphoenolpyruvate carboxykinase mRNAs are regulated in a reciprocal fashion in human hepatocytes, insulin inducing the first enzyme and repressing the latter, whereas glucagon has opposite effects. These data have interesting implications with respect to metabolic regulation and intracellular hormone signaling in the human liver.

Cloning and functional expression of the human islet GLP-1 receptor. Demonstration that exendin-4 is an agonist and exendin-(9-39) an antagonist of the receptor

A complementary DNA for a glucagon-like peptide-1 receptor was isolated from a human pancreatic islet cDNA library. The isolated clone encoded a protein with 90% identity to the rat receptor. In stably transfected fibroblasts, the receptor bound [125I]GLP-1 with high affinity (Kd = 0.5 nM) and was coupled to adenylate cyclase as detected by a GLP-1-dependent increase in cAMP production (EC50 = 93 pM). Two peptides from the venom of the lizard Heloderma suspectum, exendin-4 and exendin-(9-39), displayed similar ligand binding affinities to the human GLP-1 receptor. Whereas exendin-4 acted as an agonist of the receptor, inducing cAMP formation, exendin-(9-39) was an antagonist of the receptor, inhibiting GLP-1-induced cAMP production. Because GLP-1 has been proposed as a potential agent for treatment of NIDDM, our present data will contribute to the characterization of the receptor binding site and the development of new agonists of this receptor.

[Preparation and evaluation of anti-human growth hormone immunoserum]

Using small dosage of human growth hormone to immunize rabbit or guinea pig, it is able to induce anti-hGH antibody formation with high titre and high affinity that could be applied to hGH RIA. In the present study five rabbits and three guinea pigs were immunized with 125-200 micrograms and 250-285 micrograms per animal of hGH respectively, followed by boosters of 10-20 or 160-250 micrograms of hGH at 2-4 week intervals for 6 or 3 months. Blood was drown 1-2 weeks before each booster for determination of antibody formation. Antibody titre and affinity were successively observed and specificity of antibody was determined for the final bleeding. It was shown that titres of immune sera from guinea pigs were much higher than those of rabbit immune sera, but vice versa for antibody affinity. This might be due to larger immunogen dose used for guinea pigs than for rabbits. Fourteen different peptide hormones were tested in reference to cross-immunoreactivity to anti-hGH antibody. It could be demonstrated that the major cross-reactive hormones are hFSH and hLH, and hTSH also reacts to rabbit anti-hGH immune sera at a lesser degree. These cross reactivities are obviously owing to the molecular homogeneities between hGH and these hormones especially of their alpha-subunits.